Arbon and Comcare (Compensation)
[2019] AATA 663
•25 March 2019
Arbon and Comcare (Compensation) [2019] AATA 663 (25 March 2019)
Division:GENERAL DIVISION
File Number(s): 2016/6643
Re:Stuart Arbon
APPLICANT
AndComcare
RESPONDENT
DECISION
Tribunal:Deputy President P Britten-Jones
Member D Ben-Tovim
Date:25 March 2019
Place:Adelaide
The Tribunal affirms the decision under review
...............................[sgnd]........................................
Deputy President P Britten-Jones
Member D Ben-Tovim
CATCHWORDS
COMPENSATION – thyroid cancer – applicant worked at Maralinga –applicant was exposed to a low level of ionising radiation – whether the statutory presumption in s 7(1) of the Safety, Rehabilitation and Compensation Act 1988 applies – employment involving exposure to ionising radiation – consideration of what kind of employment the applicant was engaged in for the purposes of s 7(1)(c) of the Safety, Rehabilitation and Compensation Act 1988 – applicant was an electrician and his work duties did not require him to attend in contaminated areas – presumption does not apply – was thyroid cancer contributed to by his employment to a significant degree – causation and epidemiological studies – decision affirmed
LEGISLATION
Safety, Rehabilitation and Compensation Act 1988 (Cth), ss 5B, 7(1) and 14(1)
CASES
Bird v Commonwealth of Australia (1988) 165 CLR 1
Comcare v PVYW (2013) 250 CLR 246
Connair Pty Ltd v Fredericksen (1979) 142 CLR 485
Coward v Military Compensation and Rehabilitation Service (2006) 153 FCR 535
Elborough and Comcare (Compensation) [2016] AATA 29
Federal Broom Co Pty Ltd v Semlitch (1964) 110 CLR 626
Hatzimanolis v ANI Corportation Ltd (1992) 173 CLR 473
Seltsam Pty Ltd v McGuinness (2000) 49 NSWLR 262Sydney South WestArea Health Service v Stamoulis [2009] NSWCA 153
SECONDARY MATERIALS
Safety, Rehabilitation and Compensation (Specified Diseases) Notice 2007 (1)
REASONS FOR DECISION
Deputy President P Britten-Jones
Member D Ben-Tovim
The applicant spent some time working for the Department of Defence at Maralinga in 1978 and 1979. He now suffers from thyroid cancer and claims liability from the respondent under section 14(1) of the Safety, Rehabilitation and Compensation Act 1988 (the Act).
The applicant seeks to rely upon a presumption created by section 7(1) of the Act to assist in establishing a causal link between his cancer and his employment. The key issue in this case is whether the statutory presumption operates. For the reasons that follow, we find that it does not and that the applicant has failed to establish liability under the Act.
Background Facts
In 1971, the applicant commenced employment as an electrician with the Weapons Research Establishment branch of the Department of Defence. At some stage he did some work at Woomera and obtained the necessary security clearances which later enabled him to be chosen for some work at Maralinga.
In April 1978, the applicant spent 3 weeks working at Maralinga. He was required to carry out electrical maintenance and repair work within the Maralinga village including the installation and maintenance of generators. He attended at Maralinga and carried out similar tasks a further three times for approximately 6 weeks from October 1978, 3 weeks in July 1979 and 3 months from August 1979. All up he spent about 24 weeks at Maralinga. He travelled to and from Maralinga by train. On each trip he stayed in the old hospital which also accommodated at least four Commonwealth police officers. It was the role of those police officers to go on patrols to various sites previously used for nuclear testing situated about 30 to 40 km from the Maralinga village. These testing sites were in a prohibited area for which a pass was required to allow access. The applicant had such a pass as a result of his previous work at Woomera. None of his duties as an electrician required him to work in the prohibited area. The applicant’s work as an electrician was confined to the Maralinga village which was situated well away from the prohibited area.
The applicant was not overly busy so in order to alleviate the “severe boredom” he decided to join the police officers on their daily patrols. He did so at least once a day. They would leave the Maralinga village and travel out to the various bomb testing sites in order to make sure there were no trespassers. The applicant would sometimes drive. He enjoyed the patrols because getting in the car created some wind and some relief from the hot weather.
It is not in dispute that the prohibited area was contaminated as a result of the nuclear testing and that the applicant was exposed to ionised radiation during the patrols. The extent of that exposure is in dispute.
The applicant gave oral evidence that upon his return from each of the four trips to Maralinga, he would be de-briefed by an ASIO officer. He also spoke to the radiation protection branch and answered generic questions about the sites that he had visited in the prohibited areas. This evidence was not included in his written statement but the applicant was not challenged about it in cross-examination. I accept the evidence but I note the limited extent of the evidence on this topic.
It is not in dispute that the applicant has papillary thyroid cancer which was diagnosed in 2012 when lumps in his neck were found. He was under the care of Mr Kollias, senior consulting surgeon at the Royal Adelaide Hospital (RAH), who carried out a total thyroidectomy and a modified right neck dissection which removed some lymph nodes on 17 December 2012. He was reviewed in the RAH Thyroid Clinic in April 2014 at which time there was no evidence of disease progression. In a report from Mr Kollias, dated 8 August 2014, he said:
Papillary thyroid cancer is usually sporadic (i.e. no obvious cause), although there are some rare forms of familial papillary thyroid cancer due to germ line mutations in causative genes. Previous exposure to ionising radiation (i.e. nuclear fall-out) is also a well-recognised cause.
…
There are no other contributing factors that may have caused Mr Arbon’s thyroid cancer, apart from previous exposure to ionising radiation.
In January 2016, two additional lumps on his spine were found together with numerous metastatic carcinoma spots on his lungs. He received radiotherapy treatment in April 2016.
On 20 March 2014, the respondent had declined the applicant’s claim for compensation under section 14 of the Act on the basis that there was insufficient evidence to determine the cause of the applicant’s condition or that it was contributed to by the applicant’s employment. That decision was affirmed by a review officer on 23 October 2014.
On 5 December 2016, the applicant lodged an application for review by the Tribunal together with an application for an extension of time which was granted on 14 November 2017.
The Legislative Scheme
Section 14(1) of the Act provides:
Subject to this Part, Comcare is liable to pay compensation in accordance with this Act in respect of an injury suffered by an employee if the injury results in death, incapacity for work, or impairment.
‘Injury’ is defined in section 5A(1). The relevant part of the definition reads:
injury means:
(a) a disease suffered by an employee …
‘Disease’ is defined in section 5B(1) to mean:
(a) an ailment suffered by an employee; or
(b) …
that was contributed to, to a significant degree, by the employee’s employment by the Commonwealth or a licensee.
In section 14(1), ‘ailment’ is defined to mean “any physical or mental ailment, disorder, defect or morbid condition (whether of sudden onset or gradual development)”.
Section 5B(3) provides that “significant degree means a degree that is substantially more than material”.
Section 7(1) of the Act provides:
Where:
(a)an employee has suffered, or is suffering, from a disease or the death of an employee results from a disease;
(b)the disease is of a kind specified by the Minister, by legislative instrument, as a disease related to employment of a kind specified in the instrument; and
(c)the employee was, at any time before symptoms of the disease first became apparent, engaged by the Commonwealth or a licensed Corporation in employment of that kind;
the employment in which the employee was so engaged shall, for the purposes of this Act, be taken to have contributed, to a significant degree, to the contraction of the disease, unless the contrary is established.
Plainly, the provisions set out in section 7(1) of the Act cast a burden on a respondent to rebut a presumption of causation if an applicant satisfies (a), (b) and (c).
The relevant instrument for the purposes of section 7(1) is the Safety, Rehabilitation and Compensation (Specified Diseases) Notice 2007 (1) (the Specified Diseases Notice) which took effect from 1 July 2007. The Schedule to the instrument, which is divided into three columns, sets out the specified diseases and the specified employment relating to those diseases. Insofar as it relates to this matter, item 24 of the Schedule is referrable to diseases caused by ionising radiation. The specified employment is characterised as “employment involving exposure to the action of ionising radiation”.
Bird v Commonwealth of Australia (1988) 165 CLR 1 (Bird) was a case that involved a member of the Royal Australian Air Force who had been exposed to radioactive air and dust samples after a nuclear test. He subsequently developed cancer of the tongue with right cervical node metastasis. The relevant statutory provision at that time was section 30 of the Compensation (Commonwealth Government Employees) Act 1971 (the 1971 Act). Other than the disease being specified in Regulations rather than in a legislative instrument and the final words of that section deeming the exposure to have been a contributing factor to the contraction of the disease, the words are identical to those now found in section 7(1) of the Act.
The relevant provisions in the Regulation referred to the disease as a pathological condition caused by “radium or another radioactive substance; or x-rays”. The relevant employment was described as “employment involving exposure to or contact with radium, other radioactive substances or x-rays”.
The plurality in Bird (Mason CJ, Brennan and Toohey JJ) described the purpose of section 30 of the 1971 Act in terms of what was said in Connair Pty Ltd v Fredericksen (1979) 142 CLR 485 (Fredericksen) where the court said, at 502:
… [it is] to enable an employee to recover if he could show that the employment in which he was engaged involved a particular liability to, or a special risk of, contracting the disease from which he suffered, although he could not prove that he contracted the disease in the employment of the defendant employer.
As to the causal link between the condition and the exposure to the relevant substances, the plurality in Bird said, at 6:
Items 6 to 23 of the First Schedule and s. 30 together are thus clearly intended to provide the causal link between exposure to or contact with the substance and poisoning which has in fact been caused by the substance. Similarly, item 4 of the Schedule and s. 30 provide the causal link between exposure to or contact with radium or other radioactive substances or x-rays and a pathological condition which has in fact been caused by those substances. The Schedule does not require that the substances to which an employee was in fact exposed or in contact with during his employment be proved to be the actual cause of the poisoning or pathological condition from which a claimant is suffering. The Schedule and s. 30 avoid that necessity. But they do require that the poisoning or pathological condition from which a claimant is suffering be caused by substances of the same description as those to which the employee was in fact exposed to or in contact with during his employment.
The issues
It is not in dispute that:
(a)the applicant suffers from an ailment for the purposes of section 5B(1) of the Act;
(b)thyroid cancer is a disease of a kind specified by the Minister associated with employment involving exposure to the action of ionising radiation; and
(c)the applicant was exposed to ionising radiation.
The first issue is whether a rebuttable presumption arises under section 7(1) of the Act.
There is no dispute with respect to subsections (a) and (b) of section 7(1). The dispute arises with respect to section 7(1)(c), namely whether or not the applicant was engaged in employment involving exposure to the action of ionising radiation. If the applicant’s employment is found to be confined to the geographical area of the Maralinga village then his employment would not involve exposure to ionising radiation and therefore the rebuttable presumption would not arise. The applicant contends that his employment should not be so confined because it was by reason of his employment (as distinct from merely his duties of employment as an electrician), that the applicant was exposed to the ionising radiation. The applicant relies upon the wording of item 24 which refers to “employment involving exposure to the action of ionising radiation” to support his contention that employment should not be narrowly confined.
If the applicant establishes the requisite elements of section 7(1) then his employment is taken to have contributed, to a significant degree, to the contraction of his thyroid cancer, unless the contrary is established. It would follow that in order to rebut the presumption, the respondent would need to establish that his employment did not contribute to a significant degree to his thyroid cancer.
If the deeming provision does not apply, then the next issue for consideration is whether the applicant’s thyroid cancer was contributed to by his employment to a significant degree. This requires a consideration of the level of the applicant’s exposure to ionising radiation and a finding as to whether that level of exposure has caused his cancer.
First we will deal with the statutory presumption.
Does the deeming provision in subsection 7(1) apply?
Section 7 is in similar terms to section 30 of the 1971 Act, which was considered by the High Court in Bird at 5:
The purpose of s 30, like the purpose of a similar provision considered in Connair Pty Ltd v Frederiksen, is “to enable an employee to recover if he could show that the employment in which he was engaged involved a particular liability to, or a special risk of, contracting the disease from which he suffered, although he could not prove that he contracted the disease in the employment of the defendant employer”: per Mason J.
The applicant must establish three things before he can rely upon the rebuttable presumption in section 7(1).
The first is that he suffers from a disease. It is not in dispute and the evidence shows that he suffers from papillary thyroid cancer. The first element is satisfied.
The second element is that his disease is of a kind specified by the Minister as a disease related to employment of a specified kind. This element requires consideration of the Minister’s legislative instrument dated 21 June 2007 being the Specified Diseases Notice. Under the Specified Diseases Notice, the Minister specifies that for the purpose of s 7(1) the diseases in column 2 and the employment in column 3 of a schedule are the specified diseases and the specified employments related to those diseases. Item 24 of the Schedule specifies “diseases caused by ionising radiation” in column 2 and “employment involving exposure to the action of ionising radiation” in column 3. Thyroid cancer is a disease caused by ionising radiation so the applicant suffers from a disease that is specified in column 2. This second element is satisfied because the applicant’s thyroid cancer is a disease of a kind specified by the Minister as a disease related to employment involving exposure to the action of ionising radiation. (It remains to be determined whether or not the applicant’s employment is of a kind involving exposure to ionising radiation. This is the issue that is raised by the third element.)
The third element is whether “the employee was … engaged … in employment of that kind”, namely employment of a kind involving exposure to ionising radiation. This requires consideration as to what kind of employment the applicant was engaged in.
The applicant was engaged as an electrician to carry out works in the Maralinga village. His employment did not require him to leave the village. The applicant gave evidence, which I accept, that whilst he was in Maralinga his role was to fix things that had become broken. That role included installing generators, re-wiring electrical cables, servicing the generators, installing power points, making fans work, installing air conditioning, general maintenance and general day to day repair work. All of these activities were carried out within the Maralinga village. The applicant described his work as “spasmodic” and said that he was not required to work in hot conditions and that it was hot most of the time. The working hours were flexible.
When he had completed his work he would leave the Maralinga village and travel out to the various bomb testing sites with the Commonwealth police officers in order to make sure there were no trespassers. He did this to alleviate the severe boredom and to obtain some relief from the heat because getting in the car created some wind. It was whilst on these patrols that the applicant was exposed to ionising radiation. The applicant contends that his employment was of a kind involving exposure to ionising radiation because he undertook these patrol activities when stationed at Maralinga for work duties. We reject that contention for the reasons that follow.
Consideration of what “kind of employment” a person is engaged in requires an analysis of the inherent features of that employment. The reference to “kind of employment“ suggests the required focus is on the type of employment as opposed to the activities engaged in by the employee whilst employed. There may be some overlap. The actives engaged in by the employee may inform the question as to the kind of employment the employee is engaged in but only insofar as the activities are part of his duties.
In this case, the applicant’s duties and the tasks required to be carried out as part of his employment were confined to electrical matters in the Maralinga village - that was the kind of employment he was engaged in. Despite possessing the required clearance to access the prohibited area, the patrols to that area were not required or expected of him as part of his employment. He did no work as an electrician outside of the Maralinga village. Whilst carrying out his duties as an electrician he was not exposed to ionising radiation. The fact that he decided for reasons unrelated to his work as an electrician, namely to get some relief from the heat and the boredom once his tasks as an electrician were completed, to assist in patrolling the prohibited area does not change the kind of work he was engaged in. Nor does the fact that he spoke to ASIO about the patrols upon his return. He was not engaged by ASIO to carry out the patrols and nor was he expected to carry out patrols as part of his employment.
We conclude that the kind of work that the applicant was engaged in was as an electrician carrying out duties at the Maralinga village. Employment of this kind does not involve exposure to ionising radiation. The third element of section 7(1) is not satisfied. Exposure to radiation is not an inherent feature of being an electrician. Even if one considered the inherent features of being an electrician in the Maralinga village, one would not say that it involved being exposed to radiation.
The approach that we have taken is consistent with the approach of Deputy President Bean in Elborough and Comcare (Compensation) [2016] AATA 29 (Elborough) which was a case with similar facts. Deputy President Bean said at [27] and [28]:
As I understand it, Mr Elborough does not contend that there was any aspect of his employment duties with the PMG that required him to leave the Maralinga village and go on trips to the Forward Area. Rather, he contends that he went on these trips involuntarily as it was “something to break the monotony” of the camp, which he described as being “boring and sparse” as well as “isolated and isolating”.
Having regard to the fact that Mr Elborough’s employment duties did not require him to leave the Maralinga village and risk exposure to ionising radiation above background levels, I am not satisfied that Mr Elborough can avail himself of the deeming provision in subsection 7 (1) of the SRC Act.
We see no error in the approach of Deputy President Bean in Elborough and consequently we reject the contention of the applicant that the relevant test was whether, by reason of his employment (as distinct from merely his duties of employment as an electrician), the applicant was exposed to some risk or state of affairs that he would not otherwise have been exposed to.
Further, when considering whether the elements of section 7(1) are satisfied, assistance is not provided by the cases relied upon by the applicant such as Hatzimanolis v ANI Corportation Ltd (1992) 173 CLR 473 and Comcare v PVYW (2013) 250 CLR 246. Those cases were focussed on a different test as to whether an injury arose out of or in the course of the employee’s employment. That is not the test that is to be applied under section 7(1).
It follows that the rebuttable presumption does not operate. For the respondent to be liable, the applicant will need to establish that his thyroid cancer was contributed to, to a significant degree, by his employment.
Was the applicant’s thyroid cancer contributed to by his employment to a significant degree?
Federal Broom Co Pty Ltd v Semlitch (1964) 110 CLR 626 (per Kitto J at 632 – 633) established that a state of affairs to which a worker was exposed in employment and to which he would not otherwise have been exposed may be the cause of, or a contributing factor towards, the suffering of a disease so as to entitle the worker to compensation.
Further, in Coward v Military Compensation and Rehabilitation Service (2006) 153 FCR 535 at [29], Cowdroy J said that a disease may be contributed to by a person’s employment if caused by the circumstances in which the employment is undertaken. These cases support the finding that the applicant’s thyroid cancer may have been contributed to by his employment at Maralinga but only if the requisite degree of causation can be established.
The key matter for determination is whether the applicant’s exposure to ionising radiation contributed to a significant degree to the thyroid cancer. First, we must consider the level of exposure and whether such a level is capable of causing thyroid cancer. Next, we must consider whether the applicant’s exposure to radiation actually caused his thyroid cancer in the sense of contributing to it to a significant degree.
Both parties accept that the level of exposure was relatively low in circumstances where it was difficult to come up with a precise calculation. The real issue was whether low levels of radiation can cause thyroid cancer. The experts differed with respect to this issue.
Expert evidence from the applicant
Associate Professor Tilman Ruff is an infectious diseases and public health physician. In his reports of 26 May 2017 and 30 August 2018 he concluded that a reasonable broad estimate of the applicant’s exposure at Maralinga was in the range of 1 to 10 mSv.
Professor Ruff’s opinion is that any level of ionising radiation exposure is associated with increased risks of cancer and that there is no dose of radiation below which there is no incremental health risk. He gave oral evidence that any dose of radiation, even much lower than background levels, is very clearly associated with adverse health outcomes.
As to causation, Professor Ruff concluded in his first report as follows:
It can be stated that this exposure will have increased his long-term risk of cancer, including thyroid cancer. It is not possible to conclude that this exposure caused his thyroid cancer. While it cannot be determined with any precision how significant a role this exposure may have played in the genesis of his thyroid cancer, this exposure cannot be disregarded as a possible contributing factor.
Professor Ruff relies upon epidemiological studies to support his opinion that even low doses of radiation can increase the risks of cancer. In response to Dr Tinker’s report, Professor Ruff says that the studies “document that radiation exposures at any level increase health risks, including at levels much lower than 100 mSv” and that “all ionising radiation exposure is harmful and increases the lifetime risk of both cancer and non-cancer diseases” and “there is no level of ionizing radiation exposure which is not associated with incremental health risk.”
Professor Ruff concluded in his second report by referring to the applicant’s radiation exposure as “being a likely contributing factor to his development of thyroid cancer” and says that his “radiation exposures at Maralinga cannot be discounted as a contributing factor for both his thyroid cancer and his heart disease.”
Expert evidence from the respondent
Dr Tinker is a scientist employed as a director of the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). He is also a director of the World Health Organisation Collaborative Centre for Radiation Protection in Australia. He prepared a report dated 10 August 2018 and a Dose Reconstruction Update dated 18 December 2018. He said that in Australia very low radiation doses have been defined as below 10 mSv and correspond to the range of exposure any member of the public may experience under normal circumstances on a yearly basis from average background levels of radiation found in our environment. The annual equivalent dose to the thyroid from natural background is approximately 1.5 mSv. Dr Tinker concluded that at levels that are typical of background levels, health effects in a population or individual cannot be attributed.
Dr Tinker’s opinion expressed in the Dose Reconstruction Update was that the applicant’s radiation exposure while at Maralinga was a very low radiation exposure in the vicinity of 0.26 mSv and 1.56 mSv. This level fell well short of the high levels of radiation associated with adverse health outcomes:
The effects of high doses of radiation are extensively researched and well known. There is established evidence of harm at exposures of populations at ionising radiation doses above approximately 100 mSv. The cumulative equivalent dose to the thyroid of Mr Arbon was estimated to be significantly less than 100 mSv.
Dr Tinker concluded that there is no credible risk for the onset of his thyroid cancer from this exposure.
The applicant’s degree of exposure to any residual radioactive materials can only be assessed retrospectively. The established method for assessing the degree of exposure under those circumstances is that developed by ARPANSA. Dr Tinker documented the outcome of modelling in his Dose Reconstruction Update dated 18 December 2018 based upon a variety of exposure risks related to a range of scenarios covering frequency of participation in patrols and exposure to dust under various driving conditions.
We accept the opinion of Dr Tinker that the applicant was likely to have been exposed to a relatively low level of radiation, in the vicinity 0.26 mSv and 1.56 mSv.
Using the exposure values that Dr Tinker generated from his models, Dr Tinker estimated the lifetime risks for the onset of thyroid cancer attributable to exposure to the identified radiation was in a range from 0.055 to 0.32 extra cases per 100,000 people. Dr Tinker did not calculate a specific value for a change in relative risk based on rate-ratios.[1] However, he noted that the population risk of development of thyroid cancer due to exposure to background radiation was 14 per 100,000 people.
[1] Seltsam Pty Ltd v McGuinness (‘Seltsam’) (2000) 49 NSWLR 262, 272.
Further, in his report of 10 August 2018 Dr Tinker said:
There is no plausible exposure scenario or radiation exposure pathway from Mr Arbon’s work at Maralinga in 1978 and 1979 that would result in an equivalent dose high enough to attribute the cause of his thyroid cancer unequivocally.
The equivalent dose to the thyroid received by Mr Arbon is considered a very low radiation dose. At this equivalent dose, it is extremely unlikely that Mr Arbon’s thyroid cancer was caused by his exposure to ionising radiation during work at Maralinga.
With respect to the epidemiological studies, Dr Tinker said that there is no established scientific evidence in the literature of studies on observed health effects in radiation-exposed populations that attributes thyroid cancer to very low radiation doses.
In his oral evidence, Dr Tinker said that negative health outcomes cannot be established at low levels of exposure.
Professor Richard Fox was also called by the respondent. He is a consultant physician with considerable experience and special expertise in medical oncology and clinical haematology involving the treatment and research of patients with various forms of cancer and blood disease. He accepted that there was an association between radiation and thyroid cancer and that the higher the dose the greater the incidence of cancer. He agreed with Dr Tinker that 1 to 10 mSv is a very low exposure to radiation. He concluded that the applicant’s work for a period of up to 24 weeks at Maralinga was not responsible for his thyroid cancer. He based this conclusion on the very low levels of radiation to which the applicant was exposed whilst at Maralinga. Further, he noted that, in general, radiation induced thyroid cancer is limited to young children and possibly adolescents. He said that there is very low level evidence from Chernobyl exposure that there may be a slightly increased risk in adults, more so in women, who were exposed.
Causation and epidemiological studies
On the use of epidemiological studies in general, Spigelman CJ in Seltsam Pty Ltd v McGuinness (2000) 49 NSWLR 262 (Seltsam) said at 271-272:
Epidemiology is the study of the distribution and determinants of disease in human populations. It is based on the assumption that a disease is not distributed randomly in a group of individuals. Accordingly, subgroups may be identified which are at increased risk of contracting particular diseases.
Epidemiological evidence identifies associations between specific forms of exposure and the risk of disease in groups of individuals. Epidemiologists do make judgments about whether a statistical association represents a cause-effect relationship. However, those judgments focus on what is sometimes called in the epidemiological literature “general causation”: Whether or not the particular factor is capable of causing the disease. Epidemiologists are not concerned with “specific causation”: Did the particular factor cause the disease in an individual case?
Epidemiology, according to one exhibit, “provides a systematic method for identifying and quantifying health risks”: J K McLaughlin and R Brookmeyer, “Epidemiology and Biostatistics” in McCunney (ed), A Practical Approach to Occupational and Environmental Medicine (1994).
Epidemiology provides two types of material: first, the statistical measurement of an association between exposure and disease and, secondly, interpretation of the data to determine general causation. The second function may be performed by an epidemiologist who had no association with the study or studies which provide the raw data.
…
Most epidemiological studies identify the strength of an association by a measure called relative risk (RR). RR is defined as the ratio of the incidence of disease in exposed individuals compared to the incidence in unexposed individuals. If the relative risk equals 1.0, the risk in exposed individuals is the same as the risk in unexposed individuals. If the relative risk is greater than 1.0 the risk in exposed individuals is greater than the risk in unexposed individuals.
The following comments of Spigelman CJ are apposite to this case, noting that the Act no longer uses the word “material” but instead requires contribution “to a significant degree” (which in fact strengthens the required connection between employment and disease):
The issue in the present case is whether an increased risk did cause or materially contributed to the injury actually suffered.
There is a tension between the suggestion that any increased risk is sufficient to constitute a “material contribution”, and the clear line of authority that a mere possibility is not sufficient to establish causation for legal purposes. The latter is too well-established to be qualified by the former. The reconciliation between the two kinds of references is to be found in the fact that, as in Chappel v Hart and in the cases that suggest the former, the actual risk had materialised. The “possibility” or “risk” that X might cause Y had in fact eventuated, not in the sense that X happened and Y also happened, but that it was undisputed that Y happened because of X.
The epidemiological evidence in the present case can be expressed in terms of “increased risk”. However, in its application to determining causation in the specific case of the respondent that evidence never arises above the level of a possibility. Whether or not the increased risk “eventuated”, is the issue which must be determined. The respondent’s reliance on the passage from McHugh J was, in my opinion, misplaced.[2]
[2] Seltsam at 280.
Spigelman CJ said further:
The predominant position in Australian case law is that a balance of probabilities test requires a court to reach a level of actual persuasion. This process does not involve a mechanical application of probabilities (footnotes removed).
In Australian law, the test of actual persuasion does not require epidemiological studies to reach the level of a relative risk of 2.0, even where that is the only evidence available to a court. Nevertheless, the closer the ratio approaches 2.0, the greater the significance that can be attached to the studies for the purposes of drawing an inference of causation in an individual case. The “strands in the cable” must be capable of bearing the weight of the ultimate inference.[3]
[3] Seltsam at 284-285.
Conclusion as to causation
The experts disagree as to whether the epidemiological studies show that exposure to low levels of radiation increases the risk of thyroid cancer. However, Professor Ruff, whilst asserting a causal relationship, does not provide any real quantification of the extent of the increased risk that he considers is apparent from the epidemiological studies. He fails to establish the strength of the asserted association between low levels of radiation and thyroid cancer. He talks in his reports of an “incremental health risk” and “measurable increases in cancer risk evident with exposures of very few mSv” and “ionising radiation as a risk factor for thyroid cancer.”
In Sydney South West Area Health Service v Stamoulis [2009] NSWCA 153, a 10% increase in risk was found to have materially contributed to and therefore caused a tumour. In this case the applicant has not established the extent of any increased risk that the applicant’s exposure to a low level of radiation contributed to his thyroid cancer. On the other hand, Dr Tinker said that there was no credible risk that his exposure caused the thyroid cancer; in other words, there was no material increased risk. Dr Tinker said in oral evidence that where the level of exposure was below 100 mSv it was extremely challenging to find any clearly established health outcomes.
In our opinion, the current state of the epidemiological evidence is that a causal relationship between low levels of radiation and thyroid cancer has not been established. The link between low levels of radiation and thyroid cancer remains a possibility, which has not been established as a matter of probability. Professor Ruff himself gave evidence that it cannot be determined with any precision how significant a role his exposure may have played in the genesis of his thyroid cancer but that his exposure cannot be disregarded as a possible contributing factor. In this circumstance, we would not accept the concluding evidence of Professor Ruff that the applicant’s exposure to radiation is a likely contributing factor to his development of thyroid cancer.
Dr Tinker’s Dose Reconstruction Update estimates a risk of at most an extra 0.32 cases per 100,000 people. An increase of 0.32 cases per 100,000 people due to exposure can be compared to the underlying background case rate of 14 per 100,000 people. It follows that an increase in exposure of 1.56 mSv is likely to increase the risk of developing thyroid cancer by 2.286% (calculated by dividing 0.32 by 14 as a percentage). Such an increase would appear to be a negligible increase in risk attributable to the likely exposure to radiation during the applicant’s time at Maralinga.
We consider that any increased risk of the applicant developing thyroid cancer does not rise above the level of a possibility when applied to determining causation in the specific case of the applicant.
The evidence establishes that the applicant was exposed to a relatively low level of radiation for limited periods over 30 years before being diagnosed with thyroid cancer. The applicant relies almost solely on the epidemiological studies to establish a causal link. The words of Spigelman CJ in Seltsam are again apposite:
With respect to many diseases, medical science is able to give clear and direct evidence of a causal relationship between a particular act or omission and a specific injury or disease. There are, however, fields of inquiry where medical science is not able to give evidence of that character. There are cases in which medical science cannot identify the biological or pathological mechanisms by which disease develops. In some cases medical science cannot determine the existence of a causal relationship. Such a state of affairs is not necessarily determinative of the existence or non-existence of a causal relationship for purposes of attributing legal responsibility. Epidemiological evidence may be able to fill the gap. It is of particular potential utility in the field of what is often referred to as “toxic torts”, especially in case of disease with long latency periods.[4]
[4] Seltsam at 276-277.
In this case, medical science is unable to give clear and direct evidence of a causal relationship between the low levels of radiation experienced by the applicant and his thyroid cancer. Professor Fox said that in terms of low dose exposure to radiation, the risk of thyroid cancer has been investigated and that there is evidence of a risk, albeit, a small one. He also said that in the vast majority of cases of thyroid cancer, there is no particular aetiological factor and no known causative factor. We note, based on the authority of Seltsam, that epidemiological evidence may be able to fill the gap, but in this case we consider that the gap has not been filled. The applicant has failed to establish that the level of radiation to which he was exposed contributed to or was in any way responsible for his thyroid cancer. It follows that the applicant has failed to establish that his thyroid cancer was contributed to, to a significant degree, by his employment at Maralinga.
Decision
The tribunal affirms the reviewable decision.
I certify that the preceding 73 (seventy-three) paragraphs are a true copy of the reasons for the decision herein of Deputy President P Britten-Jones and Member D Ben-Tovim
...............................[sgd].................................
Associate
Dated: 25 March 2019
Dates of hearing: 17-19 December 2018 Counsel for the Applicant:
Mr M Roberts
Solicitor for the Applicant Tindall Gask Bentley Counsel for the Respondent: Mr B Krupka Solicitor for the Respondent Australian Government Solicitor
0
9
0