47 The first witness to give evidence on the hearing, which hearing, as I have previously indicated, commenced in late February 1996, was Mrs. Allen. Mrs. Allen's evidence in chief was comparatively brief. At the outset she gave evidence in general terms of her marriage and the life which she and Mr. Allen had had together (see paras. 11-14 (above)). Having done so, she then gave some brief evidence as to Mr. Allen's personal habits - in particular, that he was a non-smoker and that he did not take alcohol - and of his general health which, seemingly, prior to 1992 was, on the whole, good despite occasional bouts of ill-health. Having done so, Mrs. Allen said that, after Mr. Allen had commenced to work with the Department, when he would return home his clothes were very very soiled, often with a muddy substance which had a very strong smell about it and that on many occasions his arms and legs appeared to have been caked in that muddy substance - having previously lived on farms Mrs. Allen identified the smell as that of the types of chemical which were used for dipping cattle.
48 According to Mrs. Allen, from about the beginning of 1992, Mr. Allen began to complain of headaches and tightness in the chest and, on occasions, would develop a rash around his legs and body - the headaches and tightness in the chest appear to have coincided with days on which Mr. Allen was engaged in dipping cattle (Black AB 7-8). As time went by, Mr. Allen's complaints became more frequent and the headaches and pains worse. In late September 1993, Mr. Allen complained of upper abdominal pain and nausea and a feeling of fullness after eating meals and consulted his general practitioner Dr. Chappell. However, although Dr. Chappell had various investigatory tests carried out, no specific abnormality was disclosed. Despite the continuing pain and discomfort which were becoming more and more severe, Mr. and Mrs. Allen and their children took a family holiday to New Zealand in November from which trip they appear to have returned in late December.
49 As Mr. Allen's pain continued he again consulted Dr. Chappell who, after having further tests carried out, referred Mr. Allen to a consultant gastroenterologist Dr. Hope for further assessment. Dr. Hope arranged for Mr. Allen to be admitted to Lismore Base Hospital where an abdominal CT scan was performed on 7 January 1994. That scan demonstrated enlargement of the spleen and an abnormal appearance of the pancreatic body and tail either due to pancreatic inflammation (pancreatitis) or pancreatic tumour. By the time Mr. Allen was referred to Dr. Hope, Mr. Allen's condition had progressed to the stage where the gastric pain tended to radiate toward the left shoulder and Mr. Allen had lost one and a half stone over the previous two months - these symptoms, so Professor Levi, who both provided reports (Exhibit "KK" - Blue AB 47, 552) and gave oral evidence on the hearing, was later to observe (Blue AB 50), were "relatively typical of that seen for carcinoma of the body and tail of the pancreas and the duration of time is consistent with the evolution of the disease prior to diagnosis".
50 Because the results of the further tests which Dr. Hope had arranged to be carried out were suggestive of a carcinoma of the pancreas, Dr. Hope arranged for a general surgeon, Dr. Buddee, to carry out a laparotomy for the purpose of exploring the pancreas and obtaining biopsy material and also for the purpose of determining whether, if the provisional diagnosis of a tumour were confirmed, resection was possible. That laparotomy was carried out on 24 January 1994 and established, first, that Mr. Allen was suffering from Pancreatitis and, second, that he had a well differentiated ductal adenocarcinoma of the pancreas. Dr. Buddee, having consulted with (inter alia) Dr. Strong, a gastroenterological surgeon at the Princess Alexandria Hospital in Brisbane, then considered that resection of the pancreatic mass was not feasible.
51 Mr. Allen was accordingly discharged to home on 1 February where he remained until his death on 8 May 1994. During that period of three months or thereabouts, Mr. Allen became very weak and, according to Dr. Chappell (Blue AB 56), "toward the end he could not support his weight unaided", "he became barely able to hold a cup of tea", "he retained some consciousness but visual perception was poor to the end" and "his voice became weak and was reduced to a whisper in April 1994".
52 The lay witnesses who, in addition to Mrs. Allen, gave evidence in support of the claim made in the Application for Determination were Mr. Murphy, Mr. Draper and Mr. McClenan, the substance of whose evidence can be ascertained from what I have earlier written (see paras. 35-38 (above)) and thus need not be repeated here.
53 The experts who both provided reports and gave oral evidence in support of the claims made in the Application for Determination were Professor Stewart, a research scientist, Professor Levi, to whom I have earlier referred, a specialist oncologist, Associate Professor Winder, a toxicologist and Dr. McCullagh, an immunologist, the object of the tender of Dr. McCullagh's evidence, as I understand it having been to establish that Mr. Allen was immunosupressed as a result of his exposure to DDT and thus contracted pancreatic carcinoma in a shorter period that the Garabrant article had suggested. In the result, Armitage CCJ was not prepared to accept Dr. McCullagh's thesis (RAB 78) and, that being so, I limit my record of the evidence of the experts who gave evidence in support of the claim to that of Professor Stewart, Professor Levi and Associate Professor Winder.
54 The first of the expert witnesses to give evidence in support of the claim made by Mrs. Allen was Professor Stewart, the Director of the Children's Cancer Research Institute at the Sydney Childrens Hospital at Randwick and a Professor in the School of Paediatrics at the University of New South Wales. Professor Stewart holds the degrees of Bachelor of Science and Master of Science from the University of New South Wales and Doctor of Philosophy from the Middlesex Hospital Medical School within the University of London, his thesis being entitled "Effect of Inhibitors of Nucleic Acid and Protein Synthesis on Nitrosimine Carcinogenesis".
55 The Childrens Leukaemia and Cancer Research Centre is a "Major Research Centre" of the University of New South Wales. The Centre's research director is responsible for the definition, progress and integration of laboratory research by a team of eight senior investigators and the associated technical assistants, graduate students and clerical staff. The Centre's research activity is integrated with that of the staff of the Department of Haematology/Oncology, Prince of Wales Childrens Hospital.
56 In addition to his position at the University of New South Wales, Professor Stewart has also acted as a member of consultative committees convened by such Authorities as the International Agency for Research on Cancer (IARC), the National Health and Medical Research Council (NHMRC), the Australian Cancer Society (ACS), the New South Wales State Cancer Council (NSWCC), the Clinical Oncological Society of Australia (COSA) and the National Occupational Health and Safety Commission (Worksafe).
57 Despite Professor Stewart's qualifications, on the hearing before Armitage CCJ, objection was taken to the tender of Professor Stewart's report and to his giving evidence upon the ground he was not appropriately qualified, an objection which his Honour overruled.
58 In his report (Exhibit "JJ" - Blue AB 532 et seq), in a part entitled "DDT as a Cause of Cancer in Humans", Professor Stewart wrote (inter alia) as follows (Blue AB 536-538):
"Despite the various studies which have been conducted, and some suggestive data, clear evidence that DDT causes cancer is humans was not recorded until 1992. Assessing the previously available studies of cancer in humans associated with exposure to DDT, the International Agency for Research on Cancer (IARC) concluded, in 1990, that the evidence fell short of an association which is categorised as 'limited evidence of carcinogenicity in humans'. Rather the epidemiological data for DDT were appraised by the Agency as 'inadequate' to establish carcinogenicity.
Evaluations of carcinogenicity data by IARC, which involve a specially convened international panel of experts, constitute the most authoritative assessments available. In ranking human and experimental carcinogenicity data which is not wholly negative (ie. includes at least some suggestion of cancer causation), the Agency distinguishes between 'sufficient' and 'limited' evidence. 'Sufficient' evidence is indicative of definitive findings: 'limited' evidence is indicative of definitive findings: 'limited' evidence falls short of this standard. In circumstances of less than 'limited' evidence, the data are said to be 'inadequate' for evaluation of carcinogenicity. Once evaluations of the available 'human' and 'experimental' data are determined, the findings are combined in determining the carcinogenic hazard which the agent in question poses to humans. There are four categories: Group 1 - chemicals or occupational environments definitively established as causing cancer in humans (eg tobacco smoke, astestos (sic)); Group 2A - chemicals or environments which probably cause cancer in humans; Group 2B - possibly cause cancer in humans and Group 3 - chemicals or environments for which data are not adequate to establish causation of cancer in humans.
Since the 1990 IARC review of the 'human' data regarding the possible carcinogenicity of DDT, certain relevant findings have been published. The most important of these is an investigation prompted by a cohort mortality study among 5,886 chemical manufacturing workers which was completed in 1987 and which showed increased mortality due to pancreatic cancer. Twenty eight cases of pancreatic cancer and 112 matched controls were then subject to further study. DDT was associated with pancreatic cancer, the risk ratio for 'ever exposed' compared with 'never exposed' being 4.8 (Garabrant DH, Held J, Langholz B, Peters JM & Mack TM: DDT and related compounds and risk of pancreatic cancer. J Natl Cancer Inst, 84: 764-771, 1992). Among subjects who had a mean exposure to DDT for approximately 4 years, the risk was 7.4 times that among subjects with no exposure. The duration of exposure for all industrial chemicals included in this study was 2 years or more. Two DDT derivatives, Ethylan and DDD, were additionally associated with pancreatic cancer. Smoking was identified as an independent risk factor, but controlling for smoking (and other potential confounders) did not appreciably alter the risks seen for DDT, DDE or Ethylan.
A second report concerning the human carcinogenicity of DDT has involved monitoring the level of DDT breakdown products (metabolites) in the blood stream of breast cancer patients and matched controls. Mean levels of the major metabolite of DDT were statistically significantly higher in the breast cancer patients.
These reports do not definitively establish that DDT causes cancer in humans. However, it is likely that IARC evaluation of the epidemiology data as 'inadequate' would be revised upwards to at least the 'limited' category when the compound is again considered.
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Overall evaluation of carcinogenicity data for DDT
Taking the epidemiological and experimental data together, the IARC considered that DDT is a 'possible' cause of cancer in humans (Group 2B). Epidemiological data since published would have likely resulted in (at least) Group 2A classification: chemicals considered a 'probable' cause of cancer in humans."