CALVER v ACCIDENT COMPENSATION CORPORATION [2019] NZHC 1581

CALVER v ACCIDENT COMPENSATION CORPORATION [2019] NZHC 1581 [8 July 2019]IN THE HIGH COURT OF NEW ZEALANDWELLINGTON REGISTRYI TE KŌTI MATUA O AOTEAROATE WHANGANUI-A-TARA ROHECIV 2018-485-951[2019] NZHC 1581UNDER the Accident Compensation Act 2001IN THE MATTER OF an application under section 162 of the Actto appeal to the High Court on questions oflawBETWEEN ANGELA CHRISTINE CALVER asExecutrix and Trustee of the ESTATE OFTREVARTHENAppellantAND ACCIDENT COMPENSATIONCORPORATIONRespondentHearing: 16 May 2019Counsel: B H Woodhouse and T W R Lynskey for AppellantP J Radich QC and L I van DamJudgment: 8 July 2019JUDGMENT OF MALLON JTable of contentsIntroduction [1]The law [7]The evidence [14]The review [28]The District Court [31]Cover pursuant to s 20(2)(a)? [32]The basis for cover [32]Stok [35]Was Stok wrongly decided? [49]Does the Stok analysis hold under the new legislation? [53]Was mesothelioma caused by an accident under s 25(1)(b)? [80]Accident under s 25(1)(a)? [108]Conclusion on cover under s 20(2)(a) [111]Cover pursuant to s 20(2)(g) [114]A new argument [114]The basis for cover [116]Does the initial inhalation cause an injury [117]When was the personal injury sustained? [134]Second injury consequential on the first injury [137]Conclusion on cover under s 20(2)(g) [138]Result [139]Introduction[1] Deanna Trevarthen died on 5 December 2016 aged 45. Her death was causedby mesothelioma, which is a fatal cancer caused by exposure to asbestos. It can arisein individuals with relatively low exposure to asbestos. A small but significant groupof New Zealanders contract it each year. It differs from asbestosis (a fibrotic lungdisease) which develops from a high asbestos fibre concentration in the lungs resultingfrom inhaling very high doses of asbestos fibres.1[2] Ms Trevarthen contended her mesothelioma arose from contact with her fatherwhen she was a young girl. Her father worked as an electrician, an occupation whichat that time had high exposure to asbestos. When she was between the ages of fourand 10 she would hug her father when he was wearing his work clothes and she wouldalso sometime play at his work sites.[3] Before she died she sought cover under the Accident Compensation Act 2001(the Act). Acceptance of cover would have given her a range of entitlements: forexample, treatment costs, weekly compensation, a lump sum, and funeral expenses.Her claim for cover is continued by her estate.1 Office of the Prime Minister's Chief Science Advisor Asbestos exposure in New Zealand: Reviewof the scientific evidence of non-occupational risks (8 April 2015) at 10-11. The report wasincluded in the appellant's Bundle of Authorities without objection from ACC. I have referred toit for the purposes of general non-contentious background. This background includes: thatmesothelioma is a cancer of the mesothelium, which lines the pleural, pericardial, and abdominalcavities and the outer surface of the lungs, heart, and abdominal organs; that exposure to asbestoscan also cause pleural plaques, diffuse pleural thickening and pleural effusions, lung cancer andlaryngeal cancer and possibly other cancers: see p 9; and details of the number of cases ofmesothelioma each year (for example, 90 cases in 2010 and 78 cases in 2011) at p 16-17.[4] The Accident Compensation Corporation (ACC) declined cover. ACC'sposition was that mesothelioma was a gradual process condition and, as such, neededto be the result of work exposure for there to be cover. ACC's decision was upheld bythe Reviewer and by the District Court on appeal although their reasons differed.2 TheDistrict Court granted leave to appeal to this Court.3[5] The questions of law on which leave to appeal was granted were formulatedby agreement between the parties and were as follows:(a) Does mesothelioma, not caused by a work-related exposure to asbestos,amount to a "personal injury" under s 26 of the Act;(b) Did the District Court Judge err by failing to apply s 25(1)(b) of theAct?(c) Does, in the circumstances in which ACC accepts it is more likely thannot that a claimant inhaled asbestos, s 20(2)(a) and s 25(1)(b) of the Actrequire the claimant to prove that the personal injury was "caused by"the inhalation of asbestos on "a specific occasion"?[6] Ms Trevarthen's estate no longer pursues question (b).4 For the reasons thatfollow, I have found that the answers to questions (a) and (c) are yes. In answeringthese questions I have concluded that Ms Trevarthen's mesothelioma is a personalinjury by accident and as such Ms Trevarthen was entitled to cover under the Act.The law[7] A person has cover under the Act if he or she can establish:52 Bernard Lock Application for Review by Ms Deanna Trevarthen (5 December 2016); Calver vAccident Compensation Corporation [2018] NZACC 60.3 Calver v Accident Compensation Corporation DC Wellington ACR 206/17, 10 October 2018,Minute of Judge Christiansen.4 The question had arisen because of an erroneous reference in the District Court judgment tos 20(1)(a) and it is now accepted the Judge considered s 25(1)(b), albeit briefly. In submissionson this appeal, Ms Trevarthen's estate has also sought to raise alternative grounds on which therewas cover. ACC opposes this. It says it is prejudiced if these new grounds are considered at thislate stage in the process because evidence directed to them has not been sought. (See [108] and[114]).5 Accident Compensation Act 2001, s 20(1).(a) a "personal injury" as defined by s 26(1);(b) the personal injury was suffered in New Zealand on or after 1 April2002 (or cover is available through the transitional provisions); and(c) the personal injury is of a kind for which the Act provides cover.[8] Section 26 defines a personal injury as follows:26 Personal injury(1) Personal injury means—(a) the death of a person; or(b) physical injuries suffered by a person, including, for example,a strain or a sprain; or(c) mental injury suffered by a person because of physicalinjuries suffered by the person; or(d) mental injury suffered by a person in the circumstancesdescribed in section 21; or(da) work-related mental injury that is suffered by a person in thecircumstances described in section 21B; or(e) damage (other than wear and tear) to dentures or prosthesesthat replace a part of the human body.(2) Personal injury does not include personal injury caused wholly orsubstantially by a gradual process, disease, or infection unless it ispersonal injury of a kind described in section 20(2)(e) to (h).[9] For present purposes, of relevance under s 26(1) is that a personal injuryincludes physical injuries suffered by a person.6[10] Because of s 26(2), the kind of personal injury for which a person has coverdepends on whether the injury was caused wholly or substantially by a gradualprocess, disease or infection. If it was not so caused, then the personal injury will have6 Death is also relevant but for present purposes it is convenient to refer simply to physical injuries.If the physical injuries of mesothelioma are covered, then death would be covered also.cover in any of the circumstances set out in s 20(2)(a) to (j). If it was not so caused,then then the personal injury will only have cover in any of the circumstances set outin s 20(2)(e) to (h).[11] In other words, the kind of personal injury that is covered is restricted to anarrower group of circumstances when a personal injury is caused wholly orsubstantially by a gradual process, disease or infection. Of present relevance in thisnarrower group are:(a) Section 20(2)(e): "personal injury caused by work-related gradualprocess, disease or infection suffered by the person" (as defined bys 30(1)); and(b) Section 20(2)(g): "personal injury caused by gradual process, disease,or infection consequential on personal injury suffered by the person forwhich the person has cover".[12] If the personal injury was not caused wholly or substantially by a gradualprocess, disease or infection, then there will be cover if (as presently relevant) thepersonal injury was caused "by an accident to the person" (s 20(2)(a)) (with "accident"defined by s 25).[13] This is diagrammatically represented as follows:77 The document is based on a useful document presented by ACC's counsel. I have included a fullerversion of all the relevant sections so that the full context can be seen on the one page.The evidence[14] In the middle of 2015 Ms Trevarthen began to feel unwell. She had a persistentcough, chest pain, shortness of breath, night sweats, a loss of appetite and weight lossover a few months. She thought she had flu and was initially diagnosed withbronchitis. Following a chest x-ray, then a CT scan, a biopsy was undertaken on27 October 2015. She was diagnosed with malignant mesothelioma on 28 October2015. A known cause of mesothelioma is exposure to asbestos.[15] She was seen by Dr Richard Sullivan, of Canopy Cancer Care, on16 November 2015 and described by him as deteriorating rapidly. She was then seenby Anne Fraser, an oncologist with the Auckland District Health Board (DHB), on20 November 2015 and described as very frail. Dr Sullivan and Ms Fraser bothcommented in their reports that Ms Trevarthen would not be eligible for ACC fundingbecause she did not have work-related exposure to asbestos.8[16] An application for ACC funding was nevertheless made by Ms Trevarthen on4 December 2015. Ms Trevarthen said her application was on the basis ofDr Sullivan's advice that "everyone contracts mesothelioma because of asbestos".Ms Trevarthen advised that her father was an electrician and, on many occasions whenshe was between the ages of four and 10, she would play at his work sites. This wouldinclude breaking particle boards and pipes while playing at the sites. She would alsohug him every day when he got home from work in his work clothes. Ms Trevarthensaid Dr Sullivan had advised her that, given the timeframe for developingmesothelioma from when asbestos is inhaled, this scenario was "more than 'highlyprobable'".[17] ACC referred the claim to John Monigatti, an occupational physician. He saidmesothelioma was caused by asbestos in about 95 per cent of cases. Like Dr Sullivanand Ms Fraser, it was his view that Ms Trevarthen would not have cover because shehad not been exposed to the disease in an employment context. The ACC teammanager considering Ms Trevarthen's claim recorded that "mesothelioma is a gradualonset disease with a long latency period which is secondary to asbestos exposure".9The team manager considered it was not a personal injury caused by an accident viathe inhalation on a specific occasion because of its gradual onset. It recommended theclaim be declined because it was a gradual process that had not arisen from work-8 As discussed later, mesothelioma is expressly covered by the Act as a work-related disease.9 The team manager does not say on what this view is based.exposure. In accordance with this recommendation, ACC advised Ms Trevarthen on11 January 2016 that her claim for cover was declined.[18] Ms Trevarthen instructed lawyers who asked ACC to reconsider the claim forcover on the basis that the disease had arisen from the inhalation of a foreign objecton a specific occasion. ACC again sought advice from Dr Monigatti. Dr Monigatticonsidered a claim on this basis was theoretically possible, giving the example of achild getting lead poisoning from eating lead paint scrapings on a particular day. Hisview was that Ms Trevarthen would have difficulty proving this without being able to"pin-point how, where and when it actually happened". He also referred to researchfrom Professor Douglas Henderson, which said:As cumulative asbestos exposure increases, so does the likelihood ofmesothelioma as a consequence. It follows that each pattern/episode ofasbestos exposure within an acceptable latency interval contributes causallytowards the development of mesothelioma.When there are multiple exposures with an appropriate latency interval, eachone of those exposures makes a causal contribution towards mesotheliomainduction, incremental on 'background' exposure and any preceding above-'background' exposures from identified (and any non-identified) point sourcesof exposure.When there are multiple asbestos exposures one cannot point to any oneexposure as being responsible for mesothelioma induction entirely, withexculpation of the others.Furthermore, one cannot point to any one exposure and exculpate it and toblame all of the others.[19] On this basis, "and given that cover for work-related mesothelioma is alwaysawarded on the basis of cumulative rather than one-off exposure to asbestos" heconsidered causation by a specific event was not a sustainable argument inMs Trevarthen's case. ACC accepted this advice and advised Ms Trevarthen on20 April 2016 that her claim for cover was declined.[20] On 21 April 2016 Ms Trevarthen applied for a Review. In support of herapplication she filed a signed brief of evidence referring to her exposure to asbestosthrough her father's work (as described above) and Dr Sullivan's view that it washighly probable this was the cause given the timing of this exposure and when shecontracted mesothelioma.[21] Dr Glen Reid, a Sydney-based medical scientist and leading researcher intherapy to inhibit the growth of malignant mesothelioma cells, was commissioned toprovide expert advice.10 The questions he was asked to address and his answers tothem were as follows:1. Can you please explain the effect of asbestos on the mesothelial cell in thelung,Asbestos has a range of detrimental effects on the mesothelial cells thatcomprise the pleural membranes of the lung. Following inhalation, fibreswork their way through the lung and accumulate in the pleura. Theirbiopersistence is related to the needle-like structure of the fibres, which canprevent phagocytosis by macrophages and drainage through the stomata to thelymph vessels. Once accumulated in the pleural space, fibres can cause directand indirect damage to mesothelial cells. Direct damage occurs whenmesothelial cells attempt to phagocytose fibres, with experimental evidenceshowing that this can cause double-stranded DNA breaks in chromosomes, ordisruption of the mitotic spindle leading to aneuploidy. Fibres can also inducenecrotic cell death in mesothelial cells, leading to the release of the nuclearprotein HMGB1, which is highly inflammatory. This leads to chronicinflammation, recruitment of macrophages and their release of TNF-alpha, aprotein that promotes survival of damaged mesothelial cells. Additionalroutes of indirect damage to mesothelial cells are via the inflammationinduced by asbestos fibres directly, which can generate reactive oxygenspecies (ROS) and free radicals. 2. What are the minimum exposure levels required for mesothelioma todevelop? Could it develop from a single exposure/event or does it requirerepeated exposures?While there is a relationship between higher asbestos exposure and shorterlatency period, there is no minimum exposure level below which there is norisk of developing mesothelioma. In animal models, one or two injections ofasbestos are sufficient to cause peritoneal mesothelioma. While difficult toquantify fibre numbers in patients, there is epidemiological evidence that low-level (non-occupational) exposure can result in mesothelioma, such as thoseencountered during do-it-yourself home renovations. With an asbestos ban inAustralia and limit on use in New Zealand, few people are now (knowingly)exposed to asbestos in these countries, short-term exposure during homerenovations is the only known asbestos contact for many patients. Theexposures documented by this individual would be considered sufficient tocause mesothelioma.[22] Dr Bill Glass, a Wellington occupational medicine specialist with particularexpertise in asbestosis, also provided a report. He had obtained a list of places whereMs Trevarthen had lived and worked. This included working as a receptionist atDB Breweries in Newmarket when she was 23 to 24 years old. Dr Glass visited this10 These qualifications are as described by Dr Monigatti to ACC.place as a medical student in the late 1970s and knew it to have asbestos. Heconsidered it was conceivable that Ms Trevarthen had passed through the factoryduring her time as a receptionist.11 He also considered it was feasible she was exposedto asbestos as a sales representative from aged 24.[23] Dr Glass said latency from first exposure to diagnosis of mesothelioma wasusually between 45 and 55 years of age, with a range of 14 to 79 and a mean of 43 years(as per a New Zealand WorkSafe Asbestos Annual report) and exposure to asbestosresulting in mesothelioma usually occurred prior to age 30. He further commented:It is important to note that mesothelioma is a disease that is potentiallyacquired at low to high levels of exposure to airborne asbestos."The risk of mesothelioma however is considered by USEPA(2013) in theirrisk assessment, to be proportional to the magnitude and duration of inhalationexposure to asbestos." (Analysis of asbestos removal approaches for ACM inworkplace. Final Report the Allen Consulting Group 2013)Unlike asbestosis, there is no dose-response relationship with mesothelioma,although the risk is very small at low exposure levels, there is no thresholdlevel below which there is no risk." (Sen. D. Occupational Medicine 2015;65,6-14) [24] Dr Glass referred to Professor Henderson's view that it was not possible topoint to any one exposure as responsible for mesothelioma when there had beenmultiple exposures. Dr Glass then said:However given that there is no threshold, does one need to argue the necessityfor more than one exposure as causative, other than from a "greater risk"viewpoint.Furthermore where there are multiple exposures as is likely in the case ofMs Trevarthen, "any one" can be seen as causative and "which one" is notmaterial. Nor from a practical point of view can that "one event" be identified.My opinionOn the basis of the above reasoning it is my view that Ms Trevarthen has aclaim for her mesothelioma.[25] ACC provided Dr Reid and Dr Glass' reports to Dr Monigatti for review andto respond only on the question of "whether it can be established, on a balance of11 Ms Trevarthen was working as a receptionist in the 1990s (not the 1970s). This is presumablywhy neither party submits this was the likely cause of Ms Trevarthen's mesothelioma.probabilities, that the mesothelioma was caused by a single exposure".12Dr Monigatti's reply commented that Dr Reid's description of the effect of asbestoson the mesothelial cells of the pleura reflected current medical understanding. He alsoaccepted that low levels of asbestos can result in mesothelioma and Ms Trevarthen'shistory of exposure would be sufficient. He considered, however, that Dr Reid hadnot provided evidence that mesothelioma in a human "is likely to be caused by theinhalation of asbestos on a single occasion".13 He said that Dr Glass's report did notprovide this evidence either.[26] ACC sought responses from Dr Reid on two questions. The first was whetherit was possible to say whether Ms Trevarthen's mesothelioma was caused by a singleexposure or repeated exposures. Dr Reid replied as follows:As greater than 94% of mesothelioma patients report a known exposure toasbestos (latest Australian Mesothelioma Registry data, 5th Annual Report), itis highly likely that this case was caused by asbestos exposure, either in thepara-occupational setting (e.g. exposure to [her] father's work clothes) oroccupational (exposure to asbestos present in a place of work). However, it isnever possible to attribute mesothelioma to one particular exposure eventwhen multiple exposures are reported. Some mesothelioma patients reportsingle exposure events, whereas others report exposure on multiple occasions.[27] The second question was whether, when there has been a short latency periodas in Ms Trevarthen's case, it was more likely than not that the condition was the resultof repeated exposures. Dr Reid replied:The only relationship that I am aware of is that of a tendency towards ashortening of the latency period with more frequent/heavier exposure.However, this is epidemiological data and can't be applied with certainty to aparticular case. It is entirely possible that a person with a limited number ofexposures to asbestos may develop mesothelioma after a shorter than averagelatency period. To quote a recent review: "There is latency between initialexposure and disease of 15-60 years, with a mean of 40 years" (Sen, D., OccupMed, (2015) 65 (1):6-14.). This range would cover para-occupationalexposure as a child and occupational exposure as a young adult.12 In asking this of Dr Monigatti, ACC appears to have equated a "specific occasion" with a "singleexposure". I discuss this later at [96] and [104].13 This directly responds to the "single exposure" question that ACC asked of Dr Monigatti. Whatconstitutes proof of s 25(1)(b) is a question ultimately for the Court.The review[28] The Reviewer held that mesothelioma, if caused by asbestos inhalation, metthe statutory definition of "personal injury" (s 26(1)) and was not caused wholly orsubstantially by a gradual process, disease or infection (s 26(2)).14 This conclusionfollowed Stok v Accident Compensation Corporation which had held thatmesothelioma was caused by asbestos inhalation, and as such was not caused whollyor substantially by an idiopathic disease.15[29] However, the Reviewer considered Ms Trevarthen had not shown she hadcontracted mesothelioma because she had inhaled asbestos. Rather, she had shown arisk that she was exposed to asbestos inhalation. This risk was insufficient evidence.16Additionally, even if Ms Trevarthen had contracted mesothelioma because she inhaledasbestos, this would not constitute a personal injury by accident. This was becausethe definition of "accident" was not met. That definition required there to be a specificoccasion when the asbestos inhalation caused the mesothelioma. The Reviewerconcluded:17Based on the evidence before me it is not possible to identify a specificoccasion of asbestos inhalation as the cause of the mesothelioma, which meansthat the claim also fails to meet the statutory definition of an accident byinhalation.[30] The Reviewer therefore upheld ACC's decision to decline cover toMs Trevarthen.The District Court[31] On appeal to the District Court, the Judge noted the Stok decision was notbinding and was based on earlier legislation which had a different scope. Sheconsidered the Reviewer was wrong to find that mesothelioma caused by asbestosinhalation was not within s 26(2). This meant it was necessary for Ms Trevarthen to14 Application for Review by Ms Deanna Trevarthen, above n 2.15 Stok v Accident Compensation Corporation [1994] NZACAA 277, [1995] NZAR 396 perP J Cartwright.16 ACC accepts on this appeal, as it did in the District Court, that Ms Trevarthen has shown on thebalance of probabilities that she had contracted mesothelioma because she was exposed toasbestos.17 Application for Review by Ms Deanna Trevarthen, above n 2, at 22.come within one of s 20(2)(e) to (h). Of these, the Judge considered s 20(2)(e) wasthe only possibility but Ms Trevarthen's condition was not caused by a work relatedgradual process. In any event, to be an accident there needed to be the inhalation of aforeign object on a specific occasion. The Judge considered this was not establishedbecause, on the basis of Dr Glass' evidence, "there may have been multiple occasions"of inhalation.18Cover pursuant to s 20(2)(a)?The basis for cover[32] The first basis on which it is said Ms Trevarthen was entitled to cover is:(a) Mesothelioma involves significant physiological impacts on the humanbody (therefore qualifying as a personal injury under s 26(1));(b) Mesothelioma is not caused wholly or substantially by disease but isinstead caused by an external, non-disease related, agent, namelyinhalation of asbestos fibres (therefore not being within s 26(2)); and(c) The personal injury was caused by a personal injury by accident(s 20(1)(a)) either because it was "a specific event or series of events,other than a gradual process" (s 25(1)(a)) or because it was "theinhalation of an object on a specific occasion (s 25(1)(b)).[33] This submission relies partly on Stok v ACC, on which the Reviewer had alsorelied. This was a decision of the Accident Appeal Authority (then in existence) on aclaim for cover for mesothelioma arising under the Accident Compensation Act 1982(an earlier version of the accident compensation legislation).19 ACC submits that Stokwas wrongly decided and, in any event, since 1992 the clear position is that disease isexcluded from cover unless within the particular "carve outs" provided by s 26(2).18 Calver v Accident Compensation Corporation, above n 2, at [131].19 Stok v Accident Compensation Corporation, above n 15.[34] I start my consideration of Ms Trevarthen's claim for cover by reviewing Stokand the developments since then in order to determine if her mesothelioma is apersonal injury and is not wholly or substantially caused by disease. I then considerwhether Ms Trevarthen's exposure to asbestos as a young child qualifies as anaccident.Stok[35] As noted, Stok was decided under the 1982 Act. It provided cover for "personalinjury by accident". This phrase was defined as including, amongst other things, "thephysical consequences of accident" and "incapacity resulting from anoccupational disease" and as not including "damage to the body or mind causedexclusively by disease, infection, or the ageing process".20[36] Pursuant to s 28(1), occupational disease cover was available for incapacity ordeath that "results from any disease, and the disease is or was due to the nature of anyemployment in which the person was employed as if the disease were a personalinjury by accident arising out of and in the course of his employment". Section 28(5)provided that nothing in s 28 affected "the rights of a person under this Act inrespect of disease if the disease is personal injury by accident within the meaning ofthis Act".[37] It was accepted in Stok that the claimant's mesothelioma was caused byinhaling asbestos fibres as this was "almost invariably" the cause of mesothelioma.21It was not known precisely when the fibres, which went on later to cause themesothelioma, had been inhaled. This was partly because the claimant had beenexposed to asbestos fibres in two ways:2220 Accident Compensation Act 1982, s 2.21 At 6.22 At 4.(a) In 1960 to 1965 she was exposed to asbestos through shaking out andwashing her husband's overalls (he was exposed to asbestos throughhis employment at fertiliser works).23(b) From 1980 she was exposed to asbestos in her home because theceilings had been spray-coated with asbestos.[38] The medical evidence was that "mesothelioma is probably dose related but notalways".24 The claimant's house was considered to provide a greater dose of exposurethan from her husband's work overalls and it was possible to develop mesotheliomain this short time frame. However, the average latency period for the development ofmesothelioma was 30 or so years and this fitted with the exposure from her husband'soveralls.[39] One of the issues for the Authority was whether cover was excluded bymesothelioma because it was a disease. The Authority said:25In normal parlance it is accepted that a cancerous condition is considered tobe a disease. It is something which occurs generally without explanation andin very few cases can it be directly related to any external cause.In the case of mesothelioma, however, a specific and identifiable externalcause exists. For the appellant's condition to be excluded by section 2(b)(ii)of the 1982 Act the damage to her body must be caused exclusively by disease,infection or the aging process.Mr Krebs submitted that the word "exclusively" requires that there be no othercause. That, in turn, submitted Mr Krebs, invites an investigation as to thechain of causation leading to the appellant's present condition.It seems to me, but for the appellant's inhalation of asbestos fibres, that shewould not suffer from mesothelioma. Therefore I consider that the exclusiondoes not apply because her condition is not caused exclusively by the disease,but rather, the cause is exclusively the inhalation of asbestos fibres which, inturn, has produced mesothelioma.[40] Mesothelioma (with its physical consequences) was therefore not outside thedefinition of "personal injury by accident" as being harm exclusively caused by a23 Examples of common law cases involving mesothelioma contracted in a similar way are Maguirev Harland Wolf PLC [2005] EWCA Civ 01 and Caltex Refineries (Qld) Pty Ltd v Stavar [2009]NSWCA 258.24 Stok v Accident Compensation Corporation, above n 15, at 3.25 At 8 (the Authority's emphasis).disease. The next question was whether it was "personal injury by accident" eventhough it was not possible to identify the point at which the claimant inhaled theasbestos fibres that caused her mesothelioma. The Authority was satisfied that theparticular external event need not be identified.[41] This conclusion relied on ACC v Mitchell, a Court of Appeal decisionconcerning an infant who suffered an apnoeic attack (an involuntary cessation ofbreathing) which left the infant handicapped.26 There was no identifiable cause forthe attack and as such there was no evidence that it had been caused exclusively bydisease or infection. The Court of Appeal relied on the fact that the Act provided coverfor personal injury "by accident" rather than "by an accident". This wording couldencompass all accidental injuries whether or not precipitated by an external triggeringevent.27[42] Moreover, diseases caused by an external event were to be distinguished fromidiopathic diseases. The Authority said:28Also what cannot be ignored is long-established case law, a judgment of theHouse of Lords in Brintons, Limited v Turvey (1905) AC 230 in whichtraumatic as opposed to idiopathic disease was held to be an injury byaccident. Brintons v Turvey concerned a workman who was employed sortingwool in a factory when a bacillus (according to the medical evidence ortheory) passed from the wool to the eye of the workman and infected him withanthrax of which he died.It was held by a bench comprising the Earl of Halsbury LC and LordsMcnaghten and Lindley, Lord Robertson dissenting, that this was a case of"injury by accident" within the meaning the Workmen's Compensation Act1897.At page 233 of Brintons, Limited v Turvey the Earl of Halsbury LC is reportedas having said:" I think, in popular phraseology it [the Workmen's Compensation Act]excludes, and was intended to exclude, idiopathic disease; but when someaffection of our physical frame is in any way induced by an accident, we mustbe on our guard that we are not misled by medical phrases to alter the properapplication of the phrase 'accident causing injury', because the injuryinflicted by accident sets up a condition of things which medical mendescribe as disease.26 Accident Compensation Corporation v Mitchell [1992] 2 NZLR 436 (CA).27 This aspect of the reasoning of the Authority no longer applies because of changes to thelegislation.28 Stok v Accident Compensation Corporation, above n 15, at 11-12.Suppose in this case a tack or some poisoned substance had cut the skin andset up tetanus. Tetanus is a disease; but would anybody contend that therewas not an accident causing damage?"By direct analogy to the concluding comments of the Earl of Halsbury as citedabove, possibly it could be argued on behalf of the appellant that'mesothelioma is a disease; but would anybody contend that there was not anaccident causing damage'? In drawing this analogy I accept that I have, asyet, to address the accident /continuous process dichotomy.It seems to me [s 28(5)] indicates that from the inception of the scheme of theAct it was recognised that a disease not arising out of employment could be apersonal injury by accident.In section 2(1)(a)(i) it is recognised that "personal injury by accident" includes"the physical consequences of the accident:".A disease is a physical consequence. An accident is an untoward event.Obviously what must be considered now is whether the untoward occurrencesuffered by the appellant, inhalation of asbestos fibres which produced adisease condition, is an accident or a continuous process.[43] The final issue was whether mesothelioma was by "accident" or a "continuousprocess". A continuous process was not expressly excluded from cover by the Act.The issue arose because an "accident" was ordinarily a specific event or events. TheAuthority referred to Lord Porter in Roberts v Dorothea Slate Quarries Co Limitedwho put it this way:29In truth, two types of case have not always been sufficiently differentiated. Inthe one type, there is found a single accident followed by a resultant injury, asin Brintons Ltd -v- Turvey [1905] AC 230, or a series of specific andascertainable accidents followed by an injury which may be the consequenceof any or all of them, as in Burrell (Charles) & Sons Ltd -v- Selvage (1921)90 LJKB 1340. In either case it is immaterial that the time at which theaccident occurred cannot be located. In the other type, there is a continuousprocess going on substantially from day to day, though not necessarily fromminute to minute or even from hour to hour, which gradually and over a periodof years produces incapacity. In the first of these types, the resultingincapacity is held to be injury by accident. In the second it is not.[44] The Authority also referred to Gault J's view in ACC v E that:3029 Roberts v Dorothea Slate Quarries Co Limited [1948] 2 All ER 201 at 205 cited with approval inAccident Compensation Corporation v E [1991] 2 NZLR 228 (HC) at 231 and in Stok v AccidentCompensation Corporation, above n 15, at 13-16.30 Accident Compensation Corporation v E [1992] 2 NZLR 426 (CA) at 433 cited in Stok v AccidentCompensation Corporation, above n 15, at 14.It will be a matter of fact and degree in any case as to whether an occurrencenot confined to a short time can be said to constitute an accident (or series ofaccidents) rather than a process.[45] The Authority went on to discuss Pyrah v Doncaster Corporation, an Englishcase involving statutory worker's compensation.31 The case involved a nurse whoworked in a hospital for tuberculosis patients who contracted tuberculous. Over aperiod of 15 months she had been subjected to tuberculosis germs. This includedparticular instances where she was brought into close contact with tuberculosispatients. The question was whether her tuberculous was "an injury by accident" inwhich case she would be entitled to compensation under the statute against heremployer, or whether it was a disease due to a process at work. The Court held that,although it might not be possible to fix the exact dates on which the applicant inhaledtuberculous germs, on each occasion on which that occurred there was an assault ofbacilli and this constituted an accident.[46] The Authority noted that, in the workers' compensation legislation context, thecircumstances would not constitute an accident if the external factors which producedthe disease were a continuous and necessary concomitant over a long period of thework in which the person was engaged. In this context, a continuous process (such asthe inhalation of foreign particles) was an inescapable consequence of the workplaceand could not be regarded as an accident.[47] The Authority also found Burrell (Charles) & Sons Ltd v Selvage ofassistance.32 The case involved a person who developed poisoning and arthritisbecause her hands were periodically scratched while working in a copper platingdepartment of a shell factory. She was entitled to compensation for the injury by"accident" even though it was caused by a number of accidents over time which allcontributed to the injury.[48] Having discussed these cases, the Authority concluded that the claimant hadsuffered a series of accidents rather than a continuous process. Every time she inhaledasbestos fibres, that was an assault of fibre and each assault was an accident which did31 Pyrah v Doncaster Corporation [1947] 1 All ER 833.32 Burrell (Charles) & Sons Ltd v Selvage (1921) 126 LT 49, (1921) 14 BWCC 158 affirming Selvagev Burrell (Charles) & Sons Ltd [1921] 1 KB 355.not occur over such a length of time as to deprive them of their character of"accident".33Was Stok wrongly decided?[49] In this case ACC submits Stok was wrongly decided because the damage to theclaimant's body was caused exclusively by disease. It submits the fact that the diseasewas, in turn, caused by asbestos inhalation does not detract from the fact that herphysical suffering was caused by disease. Put another way, ACC contends theclaimant's physical suffering constituted the injury. That suffering was caused by adisease. The disease was caused by asbestos inhalation. The submission thereforeseparates the physical manifestations of the disease (in the form of pain and sufferingwhich is regarded as the injury) from the disease itself (regarded as the cause of theinjury).[50] I consider Stok was correctly decided. Section 2 of the 1982 Act defined"personal injury" as including "the physical and mental consequences of any suchinjury or of the accident". It excluded damage to the body caused exclusively bydisease. The claimant's disease was a physical consequence of the accident (theinhalation of the fibres) and the damage to her was not exclusively caused by diseasebecause, without that inhalation having occurred, the disease would not havedeveloped. In this way the 1982 Act distinguished between diseases that arose byaccident (they were covered) and diseases that were idiopathic (they were notcovered).34[51] In addition, it provided cover for disease suffered by an employee due to thenature of their employment. Such diseases might not qualify as personal injury byaccident, but by s 28(1) they were to be treated as though they were. As the Authoritysaid, while s 28(1) set out what constituted an occupational disease, s 28(5) provided33 ACC applied for and was granted leave to appeal this decision: Stok v Accident CompensationCorporation [1994] NZACAA 354 (leave decision). It seems the appeal was not pursued althoughI do not know why that was.34 Graeme Kennedy and Tony Deverson The New Zealand Oxford Dictionary (Oxford UniversityPress, Melbourne, 2005) at 540 defines "idiopathy" as "any disease or condition of unknown causeor that arises spontaneously". Similarly, Lesley Brown (ed) The New Shorter Oxford EnglishDictionary (5th ed, Clarendon Press, Oxford, United Kingdom) Vol 1 at 1305 defines "idiopathic"as "of a disease: not consequent on or symptomatic of another disease; having no known cause".this did not affect "the rights of a person under any provisions of this Act in respect ofa disease if the disease is personal injury by accident within the meaning of the Act".Section 28 therefore recognised that diseases could constitute "personal injury byaccident" and this reinforced the Authority's analysis that disease could qualify as aninjury under s 2.[52] The next question is whether the analysis in Stok holds following the legislativechanges made to the Act.Does the Stok analysis hold under the new legislation?[53] ACC submits the changes were made because judicial interpretation of thelegislation had expanded its cover. ACC submits the changes were intended to narrowthe scope of cover from that provided under the 1982 Act (as interpreted by the courts)and that one of the ways it did this was by covering diseases, gradual processes andinfections only in the more limited circumstances described in s 20(e)-(h).[54] In support of this submission ACC has provided commentary and othermaterial about the legislative changes. This material starts with the 1967 WoodhouseReport which led to the accident compensation legislation.35 In oral submissions atthe hearing, ACC's counsel concentrated on two passages in that Report.36 Thesewere:(a) The general basis for protection should be bodily injury by accidentwhich is undesigned and unexpected so far as the person injured isconcerned, but to the exclusion of incapacities arising from sicknessor disease.(e) On the other hand incapacities should be excluded which resultedfrom a condition of disease or sickness; [55] As the Report went on to say, the dividing line between a physical injury thathad an external cause and disease or sickness that did not was a mixed question of law35 The Honourable Justice Woodhouse Compensation for Personal Injury in New Zealand: Reportof the Royal Commission of Inquiry (December 1967).36 At [289(a) and (e)].and medicine.37 To assist with achieving certainty about where the boundary shouldbe drawn, the Report recommended cover for injuries from unexpected or undersignedexternal causes with reference to classifications in the World Health Organisation'sInternational Classification of Diseases.38 These classifications included accidentalpoisonings, foreign bodies (for example dust) entering the eye or other orifice(including the lung), sunstroke from excessive heat and the "late effects" of anyaccident.39 The Stok decision is consistent with this approach.[56] ACC's submissions go on to refer to the review and legislative developmentsbeginning in the 1980s and subsequently.40 As discussed in Todd on Torts, during the1980s the accident compensation scheme came under pressure from differentdirections.41 In one direction there was dissatisfaction with the ambit of the schemein covering personal injury by accident but not illness. In another direction wasconcern about the burgeoning expense. These concerns led to a review by the LawCommission which recommended extending the scheme to bring sickness and non-accidental incapacity under its umbrella. Consistent with this recommendation, thethen Labour Government tabled a Bill which would have created a comprehensivescheme for all persons who suffered incapacity regardless of cause.[57] This did not proceed when a new National Government was elected. Itobtained financial analysis indicating there would soon be insufficient funds to meetnew claims. It introduced changes in the form of the Accident Rehabilitation andCompensation Insurance Act 1992. Todd on Torts explains the changes made asfollows:42 a primary objective of the new Accident Rehabilitation and CompensationInsurance Act 1992 was to meet the concerns expressed in A Fairer Schemeabout costs and coverage. And one way by which this result was proposed tobe achieved was by eliminating uncertainty about the boundaries of thescheme and by reining in the ability of judges to give an expansive37 At [289(a)-(g)].38 World Health Organisation International Classification of Diseases: Manual of the InternationalStatistical Classification of Diseases, Injuries and Causes of Death (Vol 1, Geneva, 1957).39 For example at 243, 278 and 286.40 As discussed later ([136]) there were also a number of amendments made in the 1970s after theenactment of the Accident Compensation Act 1972. For present purposes, I note that the 1972 Actprovided cover for earners and motor vehicle accident victims. In 1973, cover was extended toall persons for "personal injury by accident".41 Stephen Todd (ed) Todd on Torts (8th ed, Thomson Reuters, Wellington, 2019) at [2.2.04].42 At [2.2.05].interpretation to the provisions governing its ambit. The bases for cover weresimilar to those laid down in the earlier Acts but their scope was precisely, andin some respects far more restrictively, defined. So there was cover forpersonal injury caused by an accident, by employment-related disease orinfection, by medical misadventure and by treatment for personal injury, andalso for mental or nervous shock suffered by the victims of certain specifiedsexual offences. However, whereas formerly these categories all fell withinthe broad concept of "personal injury by accident" (which had only a non-inclusive definition), they were now treated as separate categories and madesubject to a series of detailed definitions. Judicial discretion in determiningtheir limits was largely removed. This arrangement was carried over into theAccident Insurance Act 1998 and again into the Accident Compensation Act2001. Commentators heaped a good deal of opprobrium on the 1992 Act, both forits lack of any coherent policy and for its markedly reduced benefits. Yet someof the criticisms of the new Act arguably were overstated. Coverage wasreduced but only at the margins. Certain cases of mental injury henceforthwere excluded, but the core areas of coverage – physical injury by accident,medical misadventure and occupational disease – continued much as before.These categories also were similar in conception, albeit defined with muchgreater precision [58] ACC goes on to refer to the Hansard debates when the 1992 Act was introducedin support of its submission that diseases, outside of work-place diseases, were not tobe covered. ACC drew attention to the following comments (from Larry Sutherland,a Member of Parliament, at the second reading of the Accident Rehabilitation andCompensation Insurance Bill 1992):43Because the Bill will not properly recognise the problems of some people,particularly those suffering from diseases, and will not give them theopportunity to have those diseases rightfully recognised and rightfullycompensated for, there will be a further entrenchment of those groups ofpeople in our society who have become obsessed and who feel that the systemis against them and that nobody cares and nobody listens.[59] ACC also drew attention to the following comments (from the same reading):44Hon. Dr MICHAEL CULLEN: I ask the Minister, who interjects unwiselyat this point, what the difference is now between somebody who loses a legfrom an accident and somebody who loses a leg from cancer. Does the Billtreat them equally? 43 (19 Mar 1992) 522 NZPD 7100.44 (19 Mar 1992) 522 NZPD 7102.People could be foolish enough to try to mow a hedge using a Flymo – andpeople in New Zealand have been as stupid as that in recent years. They havepicked up a Flymo type of lawnmower and tried to cut a hedge with it. Theyhave suffered injury, which is totally their own fault, and under a no-faultsscheme properly they may receive earnings-related compensation.R. Hon. W.F. Birch: They pay for it.Hon. Dr MICHAEL CULLEN: They do under this Bill, too, whereas ifpeople through no fault of their own suffer a crippling disease –[60] And lastly, ACC drew attention to this comment (from Rt Hon W F Birch atthe third reading):45Indeed, I think it is useful to write into the record the first general principlestated by Woodhouse in paragraph 289: "The general basis for protectionshould be bodily injury by accident, which is undersigned and unexpected sofar as the person injured is concerned but to the exclusion of incapacitiesarising from sickness or disease." [61] In my view this history and these comments do not show that Stok was wronglydecided or that the subsequent legislation was intended to exclude cover formesothelioma suffered by someone exposed to asbestos fibres outside the workplace.They do show that a decision was made not to provide comprehensive cover for allincapacity regardless of its cause. This meant sickness or disease per se was not to becovered just as it had not been covered at the outset or in the 1982 Act. Under the1982 Act and its predecessor, cover was not normally available for, say, cancer. Asthe Authority in Stok explained, normally cancer occurs without explanation and invery few cases can it be directly related to any external cause. Mesothelioma isdifferent because it has an external cause.[62] Against this background, the words of the 2001 Act must be examined. ThisAct made the following changes or refinements to the wording (as presently relevant):(a) "personal injury by accident" was replaced with a specific list of thecircumstances in which personal injury is covered;(b) "personal injury" is no longer defined in non-exhaustive terms;45 (24 Mar 1992) 532 NZPD 7302.(c) In defining "personal injury", "physical injuries suffered by a person"has replaced "the physical consequences of any such injury or of theaccident";(d) a "personal injury caused wholly or substantially by a gradual process,disease, or infection" has replaced "damage to the body causedexclusively by disease" and there is cover only if the gradual process,disease or infection is work-related, treatment injury (previouslymedical misadventure), or it is consequential on personal injury forwhich there is cover;(e) "personal injury caused by a work-related gradual process, disease orinfection" as defined in s 30 in the 2001 Act has replaced "occupationaldisease" as defined in s 28(1) of the 1982 Act;(f) "personal injury caused by an accident" has replaced "personal injuryby accident"; and(g) "accident" is now defined although it does so broadly in terms of theaccident/continuous process distinction in the common law asdiscussed in Stok.[63] This leads to the question of whether these changes mean that s 26(2) appliesto Ms Trevarthen's personal injury, in which case the Stok analysis would no longerapply. Relevant to this is whether the personal injury is the condition suffered by theperson (here mesothelioma) or the physical manifestations of the condition (the painand suffering) that is injury.[64] This question arises because, if the kind of personal injury is simply describedas mesothelioma (a disease), then this injury was not caused wholly or substantiallyby a disease. Rather it (the disease) was caused wholly or substantially by an externalagent, namely the asbestos fibres which were inhaled. On the other hand, if thepersonal injury is described as the physical impacts on Ms Trevarthen frommesothelioma (the tumour, chest pain, physical weakness and weight loss etc) then itmight be said that those physical impacts were wholly or substantially caused by adisease (mesothelioma) and s 26(2) applies.46[65] A case which illustrates the competing approaches to this question in a differentcontext is Allenby v H.47 This case concerned whether a woman who became pregnantfollowing a failed sterilisation had suffered "personal injury" caused by medicalmisadventure.48 All five Judges of the Supreme Court considered a pregnancy in suchcircumstances was a personal injury although they expressed their reasons differently.[66] The majority judgment (Blanchard, McGrath and Wilson JJ) was given byBlanchard J. He said:49So, whenever the Act gives cover for some kind of personal injury, it isrequiring that the claimant has suffered some form of physical injury unlessthe personal injury comes within the other paragraphs of s 26(1). As theillustration provided by s 26(1)(b) indicates, "physical injuries" are thosesuffered by the claimant which have some appreciable and not whollytransitory impact on the person but which are not necessarily long-lasting orones that cause serious bodily injury.[67] Blanchard J considered the legislation had provided an expansive definition ofpersonal injury.50 He considered, for example, that where medical misadventureinvolves misdiagnosis of a disease leading to no form of treatment being given, it wasnot a natural use of the language to speak of the progression of the disease (say theenlargement of a cancerous tumour and the spreading of the cancer to another part ofthe body) as a physical injury. Yet this was covered by s 20(2).51 He consideredpregnancy (involving the development of a foetus which causes discomfort and, at46 Although the immediate cause of the physical impacts is the disease, it might still be argued thata material cause of the physical impacts was still the inhalation of the fibres and therefore that thedisease was not the substantial cause of them.47 Allenby v H [2012] NZSC 33, [2012] 3 NZLR 425.48 The case was decided before the amendments to the 2001 Act which replaced medicalmisadventure with the concept of "treatment injury".49 Allenby v H, above n 47, at [56].50 At [68].51 At [66]. At this part of his judgment, Blanchard J did not say whether it would be covered unders 20(2)(b) or (f). He had earlier (at [54]) referred to the dissenting judgment of William Young P(as he then was) in Accident Compensation Corporation v D [2008] NZCA 576 who "saw littledifference" between s 20(2)(b) or (f). He also referred to the Solicitor General's examples of anamputation of the wrong leg falling within s 20(2)(b); gangrene following amputation of the wrongleg falling within s 20(2)(f) and (g); and an adhesion caused by excessive and negligent radiation(a gradual process) (Blanchard J does not say which subsection this would fall under but it wouldseem to fall under s 20(2)(f)).least ultimately, pain and suffering) following a medical error could not bedistinguished from disease or infection following a medical error.[68] The Judge supported his analysis with the situation of a pregnancy caused bya rape. The rape (an assault) would qualify as an accident. The impregnation of thevictim was a physical consequence of the rape and should not be differentiated, for thepurpose of coverage of the scheme, from any other physical consequence, such as thetearing of the vagina (a more transitory physical consequence than the pregnancy).52[69] He said:[76] In addition, since, as we would hold, an impregnation resulting fromrape is, under s 20(2)(a), a personal injury, it must follow that an impregnationresulting from medical misadventure in the form of a failed sterilisation is alsoa personal injury. The 2001 Act, as it stood at the time, keeps cover formedical misadventure (where it is necessary to show negligence) separatefrom cover for accident. But a physical consequence which constitutes apersonal injury where accident is involved will equally be a personal injurywhere there is medical misadventure. The conclusion that there is cover underpara (b) makes it unnecessary to consider the alternative argument that thefirst respondent has cover under para (f) for the impregnation because it wasa personal injury caused by a gradual process that was personal injury causedby medical misadventure. It is worth repeating, however, that the use of theterm "personal injury" in para (f), and indeed throughout subs (2), inconnection with events that would naturally be described as illnesses ratherthan injuries, shows that, despite s 26(1)(b), the term is being given anextended meaning.[70] Blanchard J therefore considered the personal injury was the pregnancy (it wasa personal injury because of the physical impacts). He did not regard the pregnancyas being caused by a gradual process and therefore within s 26(2). Rather, it wascaused by the failed sterilisation.53 He viewed this as similar to a disease or infectionthat was caused by a negligent misdiagnosis.[71] Tipping J agreed with this analysis. In relation to the physical impacts ofpregnancy he added:[88] I am unable to accept the changes which occur to a woman's body asresult of pregnancy do not come within the compass of the expression"physical injuries" in the context of the legislation in issue. Clearly the bodychanges are of a physical kind. The only issue is whether they represent an52 At [72].53 At [80].injury or injuries for the purposes of the Act. I consider they do. In both cases(rape and failed sterilisation) the bodily changes which ensue qualify aspersonal injury. They are apt to cause a substantial degree of physicaldiscomfort and, quite often, substantial pain and suffering. The changesproduce bodily sensations which are of much greater consequence andduration than the examples given of a strain or a sprain.[72] Elias CJ approached the matter differently. She considered the initialimpregnation (which has physical impacts on the body) was a personal injury coveredby s 20(2)(b). She considered the consequential physiological changes throughpregnancy (also a personal injury) were caused by a gradual process under s 26(2) andcovered by s 20(2)(f) and s 20(2)(g).54 Where personal injuries were linked by"gradual process" or "disease" or "infection" to the original personal injury, thesubsequent personal injury was covered.55[73] As I see it, the difference between the majority reasoning and the reasoning ofElias CJ is how they view what is the personal injury and what is seen as the cause ofthat injury. The majority considered pregnancy to be an injury because it has physicalimpacts on the body which progress. The pregnancy was caused by medicalmisadventure (the failed sterilisation). Elias CJ considered the physical impacts of thepregnancy to be the personal injury. Because pregnancy is a gradual process, thosephysical impacts, after the initial impregnation, were caused wholly or substantiallyby a gradual process.[74] The difference in view between the majority and minority arose because thepersonal injury had progressive physical impacts. If it is the physical manifestationsof the injury that constitute the "personal injury", then what has caused the final stageof the injury (and whether that cause is a gradual process) might be something differentfrom what caused the first physical manifestation of the injury. The majority approachtook the injury as a whole (the pregnancy) and asked what caused it (the medicalmisadventure).[75] The majority view is the one that binds this court. The personal injury isdefined by the condition as a whole that a person has. The condition qualifies as a54 At [22]-[23].55 At [24].personal injury because it has physical impacts. Just as a sprain qualifies as a personalinjury because it has physical impacts that causes pain and suffering, so too doespregnancy, and mesothelioma, because of their physical impacts on the body. As theLord High Chancellor Earl of Halsbury put it, "when some affection of our physicalframe is in any way induced by accident, we must be on our guard that we are notmisled by medical phrases".56 His example is someone sustaining a cut to their skinwhich sets up tetanus. As he explains, "tetanus is a disease; but would anybodycontend that there was not an accident causing damage"?57 Another example, as givento ACC by Dr Monigatti in April 2016, is lead poisoning in a child who ate paintscrapings on a specific occasion.58[76] This does not mean all diseases are covered. They still need to come withins 20(2). Idiopathic diseases, that is those that develop in a person from an unknowncause, and that are not consequential on covered events, remain outside the scope ofthe Act. As the Authority said in Stok, for example, cancer is "something which occursgenerally without explanation and in very few cases can it be directly related to anyexternal cause".59 Idiopathic diseases will generally be excluded because they arecaused by a gradual (internal) process rather than a known external cause.[77] In my view this approach is not inconsistent with the Act's scheme to providecover for work-related gradual process, disease or infection. Cover for this can, intheory, arise under s 26(2)(e) through two routes: as personal injury under s 26(1)which is not personal injury under s 26(2); or as personal injury under s 26(1) whichis also personal injury under s 26(2). Which of these routes does not matter in a work-related personal injury because the s 30(1) definition essentially replicates the s 26(2)requirement for the personal injury to be caused by a gradual process, disease orinfection.60 This allows work injuries to be covered where they might not have56 Brintons, Limited v Turvey (1905) AC 230 at 233.57 Above.58 See [18] above.59 Stok v Accident Compensation Corporation, above n 15, at 8.60 The same applies with treatment injury. It may be covered because: it is personal injury that istreatment injury (s 20(2)(b), if s 26(2) does not apply); it is personal injury caused by a gradualprocess, disease, or infection that is treatment injury (s 20(2)(f) and s 26(2) applies); or it ispersonal injury caused by a gradual process, disease or infection consequential on treatment givento the person for personal injury for which the person has cover (s 20(2)(h) and s 26(2) applies).As noted earlier, William Young P (dissenting) in Accident Compensation Corporation v D, aboven 51, saw little difference between s 20(2)(b) and s 20(2)(f).qualified as an accident at common law or under workers' compensation legislation.61Further, a number of occupational diseases are expressly within s 20(2)(e) by theirinclusion in Schedule 2. Mesothelioma is one of those. Including some diseases andinfections in Schedule 2 (and thereby providing clarity in such claims) does notnecessarily show that Parliament intended that they could not be covered outside thework context on other grounds.[78] Nor does this approach deprive s 26(2) of meaning. For example, degenerationof the back may be wholly or substantially caused by a gradual process (if there is noknown external cause that triggered this, such as an initial accident). Heart diseasemay be wholly or substantially caused by a gradual (internal) process. Some gradualprocesses, diseases or infections may go on to cause other diseases. In these cases, thepersonal injury for which the person is seeking cover, will only have cover if it is of akind described in s 20(2)(e) to (h).[79] I conclude that mesothelioma is a personal injury under s 26(1) and that s 26(2)does not apply. The next question is whether it was "caused by an accident to theperson" under s 20(2)(a).Was mesothelioma caused by an accident under s 25(1)(b)?[80] The claim of "accident" before ACC, the Reviewer, and the District Court wasadvanced under s 25(1)(b). This requires "the inhalation of any solid or foreignobject on a specific occasion ". This was rejected in all forums on the basis it hadnot been shown that the total asbestos fibres that gave rise to the disease were inhaledon one occasion. A "specific occasion" was equated with a single occasion.[81] In reaching this view the Reviewer and the District Court relied on my decisionin Simm v ACC.62 ACC submits they were correct to do so. Simm concerned a claimfor cover for lung cancer caused by passive smoking in the workplace first diagnosedand treated when the 1998 Act was in force. Passive smoking was expressly excludedfrom the term "work-related gradual process, disease or infection" in the 1998 Act.61 See [46] above.62 Simm v Accident Compensation Corporation HC Wellington CIV 2005-485-965, 20 December2006, Judgment of Mallon J.There was no such exclusion in the 2001 Act. For Mr Simm to have cover under the1998 Act it was argued that passive smoking was a personal injury caused by accident.The 1998 Act equivalents of s 25(1)(a) and (b) in the 2001 Act were relied on in thealternative.[82] It was argued for Mr Simm that his lung cancer had been caused by his dailyattendances in his employer's smoke-filled lunch room. Each trip to the lunch roomwas said to be a "series of events" under s 25(1)(a). However, s 25(1)(a) covered a"series of events, other than a gradual process ". I held there was no evidence thatpassive smoking caused the lung cancer other than by a gradual process. Further, the1998 Act indicated that passive smoking was viewed as a gradual process through itsexpress exclusion from cover for work-related gradual process injuries.63 I also heldthat daily attendances in the lunch room over many years did not, on any ordinaryview, involve inhalation "on a specific occasion" under s 25(1)(b).64 I noted thats 25(1)(b), in contrast with s 25(1)(a), was confined to a specific occasion.65[83] Simm involved repeated exposure over a long period of time and there was noevidence showing other than that the inhalation of smoke over that time graduallycaused the lung cancer. But what is the case where it is possible that the injury arosefrom exposure on a single occasion or from exposure at different times collectively,but it is not possible to say which of those gave rise to the injury?[84] It is argued on Ms Trevarthen's behalf that Parliament cannot have beenintended to provide cover to someone for mesothelioma if they are able to point toevidence that they were exposed to asbestos once and once only, but to deny it in acase where it is not possible to say whether the mesothelioma was triggered by aparticular inhalation on a single occasion or not. In other words, mesothelioma is nota typical gradual process disease. Although it requires a sufficient accumulation offibres in the lungs (or dosage) before the disease can be triggered, it is not caused bythe gradual build up over time of asbestos fibres in the lungs (compared with, forexample, asbestosis, or the gradual build of lung damage from smoking, or the gradual63 At [32].64 At [35].65 At [36].build up heart disease from eating too much fatty food, if this is how those diseasesoccur).[85] In support of this submission reliance is placed on Fairchild v GlenhavenFuneral Services Ltd.66 This House of Lords' decision considered claims fornegligence brought by employees who had developed mesothelioma caused byexposure at work to asbestos dust. The employees had been exposed to asbestos fibrewith more than one employer and it was not possible to say which exposure had causedthe mesothelioma.[86] The judgment of Lord Bingham discussed mesothelioma as follows:67From about the 1960s, it became widely known that exposure to asbestos dustand fibres could give rise not only to asbestosis and other pulmonary diseases,but also to the risk of developing a mesothelioma. This is a malignant tumour,usually of the pleura, sometimes of the peritoneum. It is a condition whichmay be latent for many years, usually for 30-40 years or more; developmentof the condition may take as short a period as ten years, but it is thought thatthat is the period which elapses between the mutation of the first cell and themanifestation of symptoms of the condition. It is invariably fatal, and deathusually occurs within one to two years of the condition being diagnosed. Themechanism by which a normal mesothelial cell is transformed into amesothelioma cell is not known. It is believed by the best medical opinion toinvolve a multi-stage process, in which six or seven genetic changes occur ina normal cell to render it malignant. Asbestos acts in at least one of thosestages and may (but this is uncertain) act in more than one. It is not knownwhat level of exposure to asbestos dust and fibre can be tolerated withoutsignificant risk of developing a mesothelioma, but it is know that those livingin urban environments (although without occupational exposure) inhale largenumbers of asbestos fibres without developing a mesothelioma. It is acceptedthat the risk of developing a mesothelioma increases in proportion to thequantity of asbestos dust and fibres inhaled: the greater the quantity of dustand fibre inhaled, the greater the risk. But the condition may be caused by asingle fibre, or a few fibres, or many fibres: medical opinion holds none ofthese possibilities to be more probable than any other, and the condition oncecaused is not aggravated by further exposure. So if C is employedsuccessively by A and B and is exposed to asbestos dust and fibres during eachemployment and develops a mesothelioma, the very strong probability is thatthis will have been caused by inhalation of asbestos dust containing fibres.But C could have inhaled a single fibre giving rise to his condition duringemployment by A, in which case his exposure by B will have had no effect onhis condition; or he could have inhaled a single fibre giving rise to hiscondition during his employment by B, in which case his exposure by A willhave had no effect on his condition; or he could have inhaled fibres during hisemployment by A and B which together gave rise to his condition; but medical66 Fairchild v Glenhaven Funeral Services Ltd [2002] UKHL 22, [2003] 1 AC 32.67 At [7] (emphasis added).science cannot support the suggestion that any of these possibilities is to beregarded as more probable than any other. There is no way of identifying,even on a balance of probabilities, the source of the fibre or fibres whichinitiated the genetic process which culminated in the malignant tumour. [87] Because the medical science was not able to say at which employer theemployees had inhaled the asbestos fibres that led to mesothelioma, causation againstany particular employer could not be established on the traditional "but for" test. TheHouse of Lords held that a modified approach to causation was justified in suchcircumstances. An employee needed only to establish that each employer's negligencehad increased the employee's risk of contracting the disease.[88] Similarly in this case there is no way of identifying, even on a balance ofprobabilities, the source of the fibre or fibres which initiated the genetic process whichled to the malignant tumour from the various times at which Ms Trevarthen wasexposed to asbestos. Counsel for Ms Trevarthen's estate submits that a generousinterpretation of "a specific occasion" should be taken in this case applying similarreasoning to Fairchild. That is, on each occasion that Ms Trevarthen was exposed toasbestos, this gave rise to the risk of developing mesothelioma and, because medicalscience cannot say whether she developed her mesothelioma from one of thoseexposures or from several of them, the exposure should be treated as arising from asingle occasion for the purposes of s 25(1)(b).[89] The possible application of Fairchild to the accident compensation legislationwas raised in ACC v Ambros.68 This case involved the death of a woman where therehad been a negligent failure to diagnose, monitor and treat her appropriately. Thequestion was whether it had been proven that this failure had caused her death orwhether it would have occurred in any event because of the woman's underlyingmedical condition. The High Court had adopted a modified approach to the traditionalapproach to causation and the question was whether it was correct to do so.[90] The Court of Appeal held that the High Court was not correct to adopt thismodified approach. It reaffirmed Atkinson v Accident Rehabilitation Compensation68 Accident Compensation Corporation v Ambros [2007] NZCA 304, [2008] 1 NZLR 340.and Insurance Corporation, an earlier Court of Appeal decision.69 This had held theburden was on the claimant to prove, on the balance of probabilities, whether medicalmisadventure caused an injury and it was not sufficient to prove only the possibility(or risk) that it had.[91] In reaching this view the Court of Appeal discussed the ability of a Court todraw robust inference from the evidence and said:70[70] we note that the generous and unniggardly approach advocated inHarrild v Director of Proceedings [2003] 3 NZLR 289 (CA) was used bythe High Court in this case to modify the causation test. This, in our opinion,is not an appropriate application of the principle, given the plain words of the1998 Act and the rejection of the increased risk test in Atkinson. The generousand unniggardly approach referred to in Harrild may, however, support thedrawing of "robust" inferences in individual cases. It must, however, alwaysbe borne in mind that there must be sufficient material pointing to proof ofcausation on the balance of probabilities for a court to draw even a robustinference of causation. Risk of causation does not suffice.[92] It also discussed a range of approaches to causation in common law casesconcerning medical negligence and occupational disease, and whether they wereapplicable in the ACC context. This included the following comments:71[34] The exact question Fairchild was dealing with would not, of course,arise under a no fault accident compensation regime. There is no requirementto assign responsibility to any particular person. Conceivably, however, therecould be situations where the existence of cover may depend on the identityof the responsible agent or timing and Fairchild could have relevance in suchsituations. The principle in Fairchild appears, however, to be very limited. InBarker v Corus Lord Hoffman made it clear (at [24]) that the Fairchildexception applies only where the impossibility of proving the defendantcaused the damage arises out of the existence of another potential causativeagent which operated in the same way.[35] Any further consideration of whether Fairchild may be applicable inNew Zealand to cases under the accident compensation regime must await fora case where it arises. We do note, however, that the McGhee/Fairchildexceptions have not been without their critics. [36] We also note that the view has been expressed that theMcGhee/Fairchild line of cases should be limited to industrial diseases. itmay be inadvisable to extend [them] into the field of medical malpractice.69 Atkinson v Accident Rehabilitation Compensation and Insurance Corporation [2002] 1 NZLR 374(CA).70 Accident Compensation Corporation v Ambros, above n 68.71 Emphasis added.[93] As the Court of Appeal discussed, claims of medical negligence can give riseto causation difficulties because of the uncertainty of whether a better outcome wouldhave been achieved without the negligence. The amicus appearing on the matterproposed a modified test for causation.72 The proposed test was for there to be apresumption of causation if certain circumstances were met, which was able to bedisplaced by evidence.73[94] The Court of Appeal considered this test was not available under the legislationbecause it was inconsistent with Atkinson, explaining its decision as follows:74[79] [The amicus] suggested the modified causation test to deal with theunfairness of requiring a claimant to prove causation in cases of rare diseaseswhere scientific uncertainty is often at its greatest [80] While we consider that a liberal view should be taken of when atactical burden [the burden to present evidence available to a defendant toavoid an inference being drawn in its absence] may pass to the Corporation,we do not consider that the scheme of the legislation would allow apresumption of causation to arise in circumstances where the evidence wouldnot (without the presumption) reach the required standard for provingcausation. There is also nothing in the common law developments sinceAtkinson which would support the introduction of a presumption in cases offailures of treatment. Indeed the approach has been to relax causationrequirements rather than to create presumptions. Even the relaxation ofcausation requirements has been only in very limited circumstances.[82] Although, under [the amicus'] formulation, it is only an evidentialrather than the legal burden that passes to the Corporation, it is uncertain howmuch contrary evidence is needed to displace the presumption and, in cases oftrue uncertainty, it is likely that it would be difficult for the Corporation todisplace it. [The proposed] test would thus pass the burden of uncertainty ontothe Corporation rather than the claimant, a position incompatible withAtkinson, where a reverse onus was rejected and where a risk that the injurywas caused was deemed insufficient to prove causation.[95] In contrast with Ambros, the scientific uncertainty in this case is not about whatcaused Ms Trevarthen's mesothelioma. It has been proven, on the balance ofprobabilities, that Ms Trevarthen's mesothelioma was caused by asbestos inhalation72 The claimant was without legal representation.73 The presumption was to apply when a personal injury was alleged to have arisen from a failure ofmedical diagnosis or treatment, and the injury that occurred was the very injury the diagnosis ortreatment was intended to prevent, and it was part of the medical event for which the diagnosis ortreatment was given.74 Accident Compensation Corporation v Ambros, above n 68.and ACC accepts this. ACC does not challenge that it is more likely than not thatmesothelioma developed from the exposure to asbestos she reported – that is, whenshe hugged her father in his work overalls or played at a building site.75[96] ACC accepts it is not necessary to prove the precise occasion when the accident(the relevant inhalation(s)) occurred.76 Its position is that Ms Trevarthen's estate mustprove that the relevant inhalation of asbestos occurred on a "specific occasion" whichACC's submission implicitly equates to single incident.77 ACC submits the medicalevidence shows it is more likely than not that the mesothelioma was caused by anumber of exposures to, or the accumulation over time of, asbestos fibres.[97] I do not accept this is the proper inference on the medical evidence. The riskof developing mesothelioma increases with multiple asbestos exposure, but this is notthe same as saying that mesothelioma is more likely than not to develop from anaccumulation of fibres over time rather than on a single occasion. Dr Glass' view wasthat multiple exposures give risk to a greater risk, but "any one" can be seen ascausative and "which one" is not material. In contrast with asbestosis, he said there isno dose-response relationship and no threshold below which there is no risk. Dr Reidsimilarly said there is no minimum exposure level below which there is no risk ofdeveloping mesothelioma.[98] While the latency period for mesothelioma is usually dose related, and there isless risk of developing mesothelioma from low levels of exposure, the medicalevidence cannot identify the dosage level at which mesothelioma will develop and nor75 Another possibility is that her mesothelioma arose because she was exposed to asbestos fibres inone of her places of work as Dr Glass suggested. If this was case she would have cover for thisas a work-related disease. ACC rejected her claim when lodged on this basis because she hadclaimed it arose from exposure to asbestos at her father's work, not her own work. This has notbeen pursued. If it had been, on the evidence, I would reject it on the balance of probabilities. Atbest all that can be said is that she may have been to places where there was asbestos. Howeverthe nature of her work made it unlikely she would be exposed to asbestos at work sites at all, letalong at a dose that would give rise to an atypically short latency period.76 There are a number of District Court decisions that have held that the specific date of the accidentcausing the injury need not be pinpointed: see Anderson v Accident Compensation Corporation[2016] NZACC 63 at [19]; Murphy v Accident Compensation Corporation [2013] NZACC 398 at[46]; and Parsons v Accident Compensation Corporation [2014] NZACC 39 at fn 6. See also Lilov Accident Compensation Corporation [1996] NZAR 64 where the injury was caused either by anoral ingestion or an inhaled substance and which of those was not material because the injury hadunquestionably arisen from a specific event.77 ACC had also taken this view when instructing Dr Monigatti (see [25] above).is it known what dose of fibres were inhaled by Ms Trevarthen at any one time.Dr Glass and Dr Reid's view was that it is not and cannot be known whether hermesothelioma developed from asbestos inhaled on a particular date or on several dates.[99] This means there is uncertainty about whether Ms Trevarthen's mesotheliomadeveloped from one exposure to asbestos or cumulative exposures. It is an uncertaintyabout timing that arises because there were several opportunities for the injury to haveoccurred, and it is not possible to know what dose singularly or cumulatively gave riseto the injury. It is comparable to the Fairchild situation but the uncertainty goes towhether an "accident" is proven rather than which defendant or defendant isresponsible (as in Fairchild).[100] While Ambros does not rule out the possibility of Fairchild having somerelevance in the ACC context, it is firm that the burden to prove causation is on theclaimant. Here the issue is whether the claimant can prove "inhalation on a specificoccasion" when she cannot prove whether there was asbestos inhalation at one timethat led to her mesothelioma or whether she only contracted mesothelioma becauseshe inhaled asbestosis at several times. Ultimately this is a statutory interpretationquestion.[101] It is of interpretive interest that s 25(1)(a) refers to "a specific event or a seriesof events, other than a gradual process" whereas s 25(1)(b) refers to a "specificoccasion". The use of "event" and "occasion", however, seem only to reflect thenature of the accident being described: that is, it is a natural use of language to referto an "event" of force and inhaling something at some, possibly unknown, time (a"specific occasion").[102] The addition in s 25(1)(a) of "a series of events, other than a gradual process"reflects the common law that there can be a series of accidents (events of force) thatcause an injury which, although occurring more than once, are not a gradual process.78An example has arisen in the context of cricket. In Barrett v Accident CompensationCorporation a semi-professional cricketer, a fast bowler, sought cover for surgery for78 For example, the periodic scratching of a worker's hands that led to poisoning and arthritis: Burrell(Charles) & Sons Ltd v Selvage, above n 32.a fracture.79 The cricketer contended there had been a particular instance when he feltlow back pain while bowling and had to leave the field. ACC declined cover sayinghis fracture was from repetitive microtraumas and this was a gradual process. TheCourt held, on the balance of probabilities, the injury was the direct result of thebowling incident referred to by the cricketer. There had either been a series ofindividual stresses and a significant event that completed the fracture, or thesignificant event had initiated the fracture. 80[103] In s 25(1)(b) the accidental event is breathing in something that is in the air. Itis a similar kind of accident as that provided in s 25(1)(c) (orally ingesting something)and s 25(1)(c) (a burn or exposure to radiation or rays), each of which also requiresthat this occur on a "specific occasion" to constitute an accident. The purpose ofs 25(1)(b) appears to be to distinguish injuries that arise only because there has beengeneral exposure to solids, liquids, gases or foreign objects and so on (which will thenonly be covered if the exposure was work-related) to a specific occasion of exposure(which would align with the common-sense view of an accidental exposure).[104] Mesothelioma develops because a person has inhaled asbestos fibres of aquantity that, for that particular person, is a sufficient dose to trigger (at a later date)the disease. In my view, in this kind of case, the "specific occasion" is the occasionthat gives rise to the sufficient dose. That may be a single occasion (in which casethere has been a "specific occasion" at this time). Or the sufficient dose may arisefrom several occasions (in which case the occasion on which the last bit of asbestos isinhaled that constitutes the necessary dosage is the "specific occasion"). As Dr Glassput it, where there are multiple exposures, any one can be seen as causative and whichone is not material. There will, in the end, be an occasion that is causative.[105] This interpretation is consistent with Fairchild in that it avoids unfairlydeclining cover when a person has been exposed to asbestos more than once and,because of the nature of the disease, cannot pin-point which exposure resulted in thedisease. For example, on this approach there would be cover for a person who79 Barrett v Accident Compensation Corporation [2016] NZACC 236.80 See also Waghorn v Accident Compensation Corporation [2013] NZACC 2 at [33]-[36] (anothercricket example); compared with Booth v Accident Compensation Corporation [2012] NZACC98 (concerning a degenerative knee).contracts mesothelioma because, during home renovations, they were exposed toasbestos regardless of whether that exposure occurred on one day only (becauseasbestos was in one part of the house) or on several days (because asbestos was foundin two different parts of the house on different days).[106] This may be a generous interpretation of "on a specific occasion" but it is openon the words Parliament has used. Those words do not say that the foreign object musthave been inhaled by a person only once. The words are less precise than that. Agenerous, unniggardly interpretation is available.81 It does not inappropriately movethe burden of proof to ACC. It recognises that mesothelioma can be caused byaccidental inhalation of asbestos fibres which may have happened more than once. Ona purposive approach "a specific occasion" is intended to distinguish between injuriesthat are caused by a triggering external, non-continuous event and those that are causedonly because of repetitive or continuous inhalation over time. This fits with the otherhappenings which qualify as an accident under s 25.82[107] I therefore conclude that an accident under s 25(1)(b) is established.Accident under s 25(1)(a)?[108] This conclusion makes it unnecessary to consider s 25(1)(a). This was notraised on Ms Trevarthen's behalf before the Reviewer or the District Court. It is notone of the questions of law on which leave was given. ACC submits it is prejudicedif this new basis for "accident" is considered. This is because it says that evidencewould be needed as to whether the inhalation of fibres was a gradual process.[109] I do not accept this claimed prejudice. The evidence is that there was morethan one possibility for when Ms Trevarthen was exposed to asbestos fibres and anyone of them could have been causative. There is evidence that there is no dose-response relationship with mesothelioma and no threshold level below which there isno risk. Whether breathing in asbestos fibres on one or more dates is an event or series81 Harrild v Director of Proceedings [2003] 3 NZLR 289 (CA) at [19], [37] and [130].82 In addition to ss 25(1)(a), (ba) and 25(1)(c) mentioned above, ss 25(1)(d) (relating to theabsorption of chemicals through the skin) and 25(1)(e) (exposure to the elements, extremes oftemperature or environment) require the event to occur "within a defined period of time notexceeding 1 month".events as opposed to a gradual process is a legal question. The Authority in Stokdecided it was not a gradual process. Consistent with the view I have reached unders 25(1)(b), I agree that the inhalation of fibres that caused Ms Trevarthen'smesothelioma was a specific event or series of events rather than a gradual process.[110] Potentially more problematic for Ms Trevarthen's claim that she suffered anaccident of this kind, is whether the inhalation of fibres was "the application of force external to the body". This requirement was not in the 1982 Act under which Stokwas decided. For Ms Trevarthen it is said the application of force was the hugs thatshe received from her father. It is not, however, known whether Ms Trevarthencontracted mesothelioma from fibres inhaled when she hugged her father or fromfibres in the air when she was playing at worksites. Moreover, there is nothing tosuggest that any force, beyond that of breathing, is required to inhale the fibres.Section 25(1)(b) is the provision that concerns this kind of force. While I do not reacha final view on this, I consider it to be more a difficult argument for Ms Trevarthen.Conclusion on cover under s 20(2)(a)[111] I conclude that Ms Trevarthen's mesothelioma was a personal injury causedby an accident to her.[112] The personal injury is mesothelioma. Like a sprain (or a pregnancy followinga failed sterilisation), it is a personal injury because of its physical impacts on the body.Once a person has mesothelioma, those physical impacts are progressive, but the causeof the physical impacts as they progress (the fact that the person has mesothelioma)are not to be separated from the cause of the mesothelioma itself.[113] Ms Trevarthen's mesothelioma was caused by an accident because it wascaused by inhalation on a specific occasion. A specific occasion occurred at the timeat which there was a sufficient dose of asbestos fibres inhaled to (later) trigger thedisease. The specific occasion may have been from exposure at one time (in whichcase that one time is the "specific occasion"). If there was exposure at several times,then the specific occasion is the occasion on which the last amount of fibres thatconstitutes the necessary dosage to trigger the disease was inhaled.Cover pursuant to s 20(2)(g)A new argument[114] The claim for cover under s 20(2)(g) is new. ACC says it is prejudiced byMs Trevarthen's estate seeking to raise this basis for cover for the first time on thisappeal. It says it has not had the opportunity of presenting evidence that would berelevant to this ground.[115] My conclusion on cover under s 20(2)(a) means it is unnecessary to considers 20(2)(g). However, as is illustrated by Allenby, there may not be much differencebetween them in some cases. It may be useful to determine if a different conclusionwould be reached through s 20(2)(g) as a way of testing the analysis under s 20(2)(a).In doing so, I will keep in mind ACC's objection and take into account ACC's concernthat I may not have all the relevant evidence.The basis for cover[116] Under this alternative route to cover, the argument is that:(a) there are two personal injuries (s 26(1)):(i) the first personal injury occurs when the fibre enters the lung;and(ii) the second personal injury occurs when mesotheliomadevelops;(b) Ms Trevarthen would have cover for the first personal injury (it meetsthe requirements of s 360).(c) The second personal injury is caused by a disease (s 26(2)) and iscovered under s 20(2)(g) because it is consequential on personal injury(the first personal injury) for which the person has cover.Does the initial inhalation cause an injury[117] The argument that the initial inhalation of asbestos fibres gives rise to apersonal injury is consistent with the view that has been taken in common law cases.The issue has arisen in those cases in the context of workers' compensation claims orclaims for negligence against employers when it has been necessary to determine whenpersonal injuries were first suffered.[118] The first of these is a decision of the House of Lords in Rothwell v Chemical& Insulating Co Ltd.83 The case involved employees suing their employer fornegligently exposing them to asbestos dust. The evidence was that the employees haddeveloped pleural plaques (fibrous thickening of the pleural membrane) around theirlungs. These plaques were caused by exposure to asbestos and indicated that theemployees had inhaled asbestos fibres. As noted in the decision, asbestos fibres couldcause life-threatening or fatal diseases such as asbestosis or mesothelioma. But thepleural plaques themselves caused no symptoms (they caused neither impairment oflung function or disablement). While they did increase their susceptibility to theharmful diseases that can arise from inhaling asbestosis fibres, the risk of developinga disease from the asbestos fibres did not amount to damage for the purposes ofestablishing a cause of action in tort.[119] In reaching this conclusion, Lord Hoffman explained:[7] Some causes of action arise without proof of damage But a claimin tort based on negligence is incomplete without proof of damage. Damagein this sense is an abstract concept of being worse off, physically oreconomically, so that compensation is an appropriate remedy. It does notmean simply a physical change, which is consistent with making one better,as in the case of a successful operation, or with being neutral, having noperceptible effect upon one's health or capability.[8] How much worse off can one be? An action for compensation shouldnot be set in motion on account of trivial injury. [Under] the Limitation Act the primary rule is that time runs from the date on which the cause of actionaccrues. In an action for negligence that means the date upon which theclaimant suffered damage which cannot be characterised as trivial. [120] The next case is a decision of the High Court of Australia in Alcan Gove PtyLtd v Zabic.84 The case concerned a worker who had inhaled asbestos fibres in the83 Rothwell v Chemical & Insulating Co Ltd [2007] UKHL 39; [2008] 1 AC 281.84 Alcan Gove Pty Ltd v Zabic [2015] HCA 33, (2015) 257 CLR 1.course of his employment between 1974 and 1975. He first experienced symptoms ofmesothelioma in 2013 and 2014. He commenced proceedings against his employerseeking damages for personal injury. Whether he could bring this claim depended onwhether the cause of action arose before 1 January 1987. Otherwise the claim wasbarred by the Workers Rehabilitation and Compensation Act (NT) and he wouldinstead receive the more limited compensation provided under that Act.[121] The evidence at trial was summarised by the High Court as follows:85The expert evidence given at trial was that asbestos fibres are hydratedsilicates of aluminium and magnesium which are known to generate oxygenfree radicals capable of setting off adverse genetic changes in susceptible cells.When asbestos fibres are inhaled they work their way to the periphery of thelung, eventually through the visceral pleura and ultimately onto the parietalpleura. Mesothelial cells form part of the parietal pleura. They contain"oncogenes" which may be so influenced by methylation and acetylationcaused by free radicals as in some cases to lead to the development ofabnormal "switches" in the genetic regulation of cell reproduction. Initialmolecular changes occur in the mesothelial cells of the pleura soon afterinhalation of asbestos fibres. To begin with, those changes are asymptomatic,and otherwise undetectable, and do not in all cases lead to mesothelioma. Incases like the respondent's, however, where they do lead to mesothelioma, thechanges typically lie dormant for years, often for decades, until an unknown"trigger" sets off the development of abnormal genetic switches resulting inmalignancy and the "domino effect" that culminates in the malignantmesothelial tumour which constitutes mesothelioma.[122] The High Court considered it could be inferred that the asbestos fibres inhaledbetween 1974 and 1977 then or shortly afterwards resulted in initial molecular changesto mesothelial cells; these mesothelial changes ultimately resulted in the malignantmesothelial tumour; the initial molecular changes were initially asymptomatic andundetectable and were likely to have lain dormant until between one to five yearsbefore the first manifestation of symptoms; and an unknown trigger set off thedevelopment of the abnormal genetic switches that resulted in malignancy.8685 At [5].86 The Court discussed the evidence as to the trigger that had caused the cells to become malignant.If the trigger was external (for example, the consequence of smoking) then the earliest point atwhich the mesothelial cell changes were bound to lead to mesothelioma would have been whenthe person started smoking. Where the trigger was endogenous (meaning a state of affairs insidethe cells) logically it could be inferred that, once the initial mesothelial cell changes occurred, theywere bound to lead inevitably to mesothelioma. The Court considered the evidence supported theposition that the trigger was endogenous.[123] The relevant provision in the Workers Rehabilitation and Compensation Actreferred to a cause of action for "an injury to or death of a person" arising before1 January 1987. It defined "injury" as including a disease, and "disease" as includinga physical "ailment, disorder, defect or morbid condition, whether of sudden or gradualdevelopment".[124] A cause of action arose when there were facts existing that gave rise to the rightto sue. As actual damage or injury was an essential element of a cause of action innegligence for personal injury, it was necessary to determine if the initial molecularchanges to mesothelial cells was actual damage or injury. The Court found that it was,reasoning as follows:45 The question then is whether, as a matter of law, there is any reasonwhy the initial changes in the mesothelial cells which it could be inferred werebound from the time of their onset to lead inevitably and inexorably to themesothelioma from which the respondent now suffers should not be seen ascompensable damage sufficient for the respondent's cause of action innegligence to have accrued at that point.46 It assists to answer that question to consider what the position wouldhave been if, at the time the initial mesothelial cell changes occurred, therehad been evidence available to establish that they had occurred and that,because of the respondent's predisposition to mesothelioma, they were boundinevitably and inexorably to lead to mesothelioma.47 In those circumstances, the respondent would have had a cause ofaction in negligence for damages for personal injury caused by the inhalationof asbestos fibres, which was bound to lead to mesothelioma. The malignanttumour would not have begun at that point and therefore there would remaina chance that the respondent would die from other causes before the tumourbegan. But, even so, the fact that the respondent would otherwise be boundto die from mesothelioma would be sufficient to found a cause of action innegligence for damages for loss of expectation of life; and clearly, if themalignant tumour began before the matter came to trial, the respondent wouldbe entitled to add to his claim for damages the fact that the tumour had begun.48 Parity of reasoning dictates the same result here. Given that with thebenefit of hindsight it can be seen that initial mesothelial cell changes occurredshortly after the respondent's inhalation of asbestos fibres, and that they werebound to and did lead inevitably and inexorably to the malignantmesothelioma from which he now suffers, the respondent's cause of action innegligence accrued when those initial mesothelial cell changes occurred and,as the Court of Appeal held, damages for the mesothelial tumour from whichhe now suffers are recoverable in that cause of action.[125] Determining that the changes in the cells from the asbestos fibres wouldinevitably lead to mesothelioma, enabled the Court to distinguish the case from adecision of the New South Wales Court of Appeal in Orica Ltd v CGU Insurance Ltd.87There the Court had held that a person who had inhaled asbestos fibres had not sufferedcompensable damage and a cause of action did not accrue unless and untilmesothelioma develops. As one of the Judges put it, inhalation of asbestos fibreswhich leads to pleural thickening of the lung at the time of trial, but which had causedno physical discomfort or disability, with only the potential for more seriousdevelopments, did not amount to physiological changes that amounted to actionableinjury. The injury had not given rise to any harm in these circumstances. The Courtin Alcan noted that the approach taken in Orica was similar to that taken by the Houseof Lords in Rothwell.88[126] Rothwell was discussed in Dryden v Johnson Matthey Plc, a decision of theUnited Kingdom Supreme Court.89 The case concerned workers who were negligentlyexposed to platinum salts which led them to develop platinum salt sensitisation. Thissensitisation meant they would develop an allergic reaction (involving physicalsymptoms such as running eyes or nose, skin irritation, and bronchial problems) ifthey were further exposed to platinum salts. The sensitisation occurred because theimmune system reacted to the molecules not normally found in the body by producingantibodies. These reacted with the molecules and provoked particular cells to releasehistamine which caused the allergy symptoms.[127] Workers who had developed this sensitisation were no longer permitted towork for their employer where they might be further exposed to platinum salts. Theysued their employer in negligence and for a breach of a statutory duty for their financialloss arising from this. One of the questions for the Supreme Court was whetherplatinum salt sensitisation was an actionable personal injury. If it was not, the claimwould be one for economic loss, which would not necessarily be actionable.[128] The Supreme Court held the platinum salt sensitisation was actionable personalinjury. It noted the cases tended to use personal injury interchangeably with physical87 Orica Ltd v CGV Insurance Ltd (2003) 59 NSWLR 14.88 At [15].89 Dryden v Johnson Matthey Plc [2018] UKSC 18, [2019] AC 403, [2018] 2 WLR 1109, [2018]ICR 715, [2018] 3 All ER 755.injuries (where there was no psychiatric injury to complicate matters).90 The caseshave considered personal injury to include: pain, suffering and loss of amenity; aphysical change which makes a person appreciably worse off in their health orcapability; an injury sustained to a person's physical capacity for enjoying life; and an"impairment". Further, a personal injury can be hidden and symptomless.91[129] The Supreme Court rejected the argument that the workers had only a risk ofdeveloping an actionable injury (that is, the risk of developing an allergy). In doingso, the Supreme Court distinguished Rothwell. The pleural plaques in that case werenothing more than a maker of exposure to asbestos dust. They were symptomless inthemselves and did not lead to or contribute to any condition which would producesymptoms even if the sufferer was exposed to further asbestos dust.[130] In contrast with Rothwell, the Supreme Court considered the workers' bodieswere now in a state that they needed to avoid further exposure to platinum salts.92 Thiswas no different from a person who may have developed a sensitivity to something ineveryday life such as sunlight (which the employer accepted would amount to a deficitthat would be characterised as a personal injury).93 The workers had suffered apersonal injury here because their bodily capacity for work had been impaired and asa result they were significantly worse off.94[131] To summarise:(a) Personal injury in common law negligence cases, which is often usedinterchangeably with physical injuries, includes the physical impactsand bodily impairment of disease;(b) Physical injuries sufficient to give rise to a cause of action in negligencemust give rise to non-trivial harm;90 At [12].91 At [27].92 At [43].93 At [38].94 At [40].(c) Physical injuries can qualify as non-trivial harm even if they areasymptomatic.(d) They will do so where they have later caused personal injury (a diseasewhich has adverse physical impacts or impairment) and it can be saidthat the earlier, asymptomatic physical injuries were the cause.(e) Mesothelioma involves physical injuries which would constitutedamage for a common law action in negligence.(f) The initial changes to the body from inhalation of asbestos fibreconstitutes physical injuries constituting damage for a common lawaction in negligence if it can be said, with the benefit of hindsight, thatthe mesothelioma that later developed inexorably and inevitably camefrom those changes.[132] For Ms Trevarthen it is contended that the initial cell changes caused by theinhalation of asbestos which went on to cause mesothelioma were personal injury.Reliance is placed on evidence from Dr Reid that, once asbestos fibres accumulate inthe pleural space, they can cause "direct and indirect damage to the mesotheliomacells" and his explanation of the nature of that damage.[133] Although Dr Reid did not expressly say so, I understand from his explanationthat the inhalation of the fibres causes the damage he describes (or at least some of it)if mesothelioma later develops. Evidence directly addressing this would be helpful,as would any evidence about the time when this direct and indirect damage occurs(potentially confirming the evidence in Alcan). If this damage goes on to causemesothelioma, then arguably it may constitute bodily impairment (giving rise to a lossof expectation of life) and therefore constitute a physical injury and a personal injuryunder s 26(1).When was the personal injury sustained?[134] If the initial indirect and direct damage to the cells from inhaling fibres is apersonal injury, the next question is whether it was suffered on or after 1 April 2002.The medical evidence does not directly address when this damage would haveoccurred. Assuming, as seems to be the implication of the medical evidence (and asper Alcan), that it was soon after inhaling the fibres, then this was between 1975 and1981 (when Ms Trevarthen was between four and 10 years old).[135] Proceeding on that basis, Ms Trevarthen's claim for cover would need to comewithin s 360 of the Act. This means that she would have cover only if:(a) She would have had cover under the 2001 Act had the injury occurredon or after 1 April 2002; and(b) She would have had cover under the Act that was in force at the timethat the person suffered the injury.[136] For the reasons I have discussed under the first basis on which cover is claimed,I have found that inhaling the fibres was an "accident" under the 2001 Act. The Actin force at the time she suffered the injury was the 1972 Act. By 1974 the AccidentCompensation Act had been amended to cover "personal injury by accident" and thiswas defined in the same way as the 1982 Act considered in Stok. Given my view onStok, I consider Ms Trevarthen would have had cover under the Act in force at the timeof exposure. The initial injury to Ms Trevarthen when the fibres entered her bodywould constitute an accident (rather than a continuous process) and would constitute"physical consequences of the accident" and would not have been "exclusivelycaused by disease".Second injury consequential on the first injury[137] If there is initial damage from the inhalation of fibres that constitutes personalinjury, and that injury would have been covered by the legislation at the time the injuryoccurred, the second personal injury (the development of mesothelioma) would beconsequential on the first injury as required by s 20(2)(g).Conclusion on cover under s 20(2)(g)[138] Ms Trevarthen's estate seeks to rely on this alternative basis of cover only ifs 26(2) applies. In my view it does not apply. If it does apply, it leads to the, arguably,artificial division of the mesothelioma for which cover is needed from the initialpersonal injury at the time of the asbestos exposure for which no cover would beneeded at the time it was sustained (it being symptomless at this initial stage). I donot reach a final view on whether there would be cover under s 20(2)(g). It is not theway it was argued in the District Court, or earlier, and it was not the subject of leaveto appeal. However, the analysis as far as it goes, suggests there may not be anydifference in outcome whether s 26(2) applies or not. Under either basis for cover, thecritical issue is whether there has been an "accident" as defined in s 25. In my view,there has been.Result[139] The answers to the questions of law on which leave was granted have beengiven earlier.95 The appeal is allowed. The District Court's decision is set aside.[140] Ms Trevarthen was entitled to cover under the Accident Compensation Act2001 for mesothelioma because this was a personal injury caused by an accident toher. If there is any issue concerning costs, brief memoranda may be submitted by theparties within two weeks of the date of this judgment.Mallon J95 At [6] above.