Breast Cancer at the ABC Toowong Queensland Final Report of the Independent Review and Scientific Investigation Panel Panel members Bruce Armstrong (Chair) Sydney Cancer Centre, Royal Prince Alfred Hospital and School of Public Health, The University of Sydney Joanne Aitken Viertel Centre for Research in Cancer Control, The Cancer Council Queensland Malcolm Sim Monash Centre for Occupational and Environmental Health, Department of Epidemiology & Preventive Medicine, Monash University Norman Swan, Producer and Presenter of the ABC’s Health Report, Australian Broadcasting Corporation 2nd June 2007 Breast Cancer at the ABC Toowong Queensland - Final Report Page 1 of 75 Table of Contents Summary........................................................................................................................3 Background....................................................................................................................6 Investigations .................................................................................................................8 Findings........................................................................................................................10 Epidemiology of breast cancer at the ABC Toowong .............................................10 Observed number of breast cancers .....................................................................10 Expected number of breast cancers......................................................................10 Workplace and other exposure history of women who had breast cancer or other breast tumours or lumps...........................................................................................13 Women with breast cancer...................................................................................13 Women with other breast tumours or lumps........................................................17 Survey of the site for possible sources of carcinogenic exposure ...........................18 Measurement of exposure to electromagnetic fields and ionising radiation............20 Radiofrequency electromagnetic fields (RF).......................................................20 Extremely low frequency electromagnetic fields (ELF)......................................21 Ionising radiation .................................................................................................23 Review of published literature on risk factors for breast cancer .............................25 Feedback from the community following release of the Panel’s third interim report and subsequent news media coverage......................................................................30 Additional cases of breast cancer.........................................................................30 Possible causes.....................................................................................................30 Interpretation................................................................................................................35 Conclusions..................................................................................................................40 Acknowledgements......................................................................................................41 Appendices...................................................................................................................42 Appendix 1: Questionnaire ..................................................................................43 Appendix 2: Hazards assessment.........................................................................61 Appendix 3: Report on water testing ...................................................................69 Appendix 4: Report on ELF measurements.........................................................71 Appendix 5: Report on ionising radiation measurements....................................72 Breast Cancer at the ABC Toowong Queensland - Final Report Page 2 of 75 Summary After two attempted, earlier investigations, the Australian Broadcasting Corporation (ABC) appointed, in July 2006, the Independent Review and Scientific Investigation Panel to investigate an apparent cluster of breast cancers in women employed at its Toowong studios in Brisbane, Australia. The Panel reviewed relevant scientific literature, investigated the epidemiology of breast cancer in the Toowong female workforce, interviewed affected women about their work and workplace and known risk factors for breast cancer, and investigated the site for possible contamination with or high levels of exposure to known or suspected environmental risk factors for breast cancer. Thirteen women who had worked at the ABC Toowong were found to have been diagnosed with breast cancer between 1st January 1994 and 30th June 2006. An additional woman was probably diagnosed with breast cancer while working there in this period, but the details were not confirmed. Ten women were diagnosed with invasive breast cancer while still employed at Toowong; the expected number, based on breast cancer rates in all Queensland women, was 1.6 (standardised incidence ratio (SIR) 6.25, 95% confidence interval (CI) 3.0-11.5, P=0.000001). This suggests that the likelihood of this event occurring by chance is about one in a million. This, however, may oversimplify the situation and, when further analyses are performed, adjustment of the P-value for implied multiple comparisons increased its estimated value to 0.04. That potentially increases the likelihood of the cluster occurring by chance to one in 25. Counterbalancing that is our finding that the longer the time of ABC employment, the greater the risk. We found a significant trend of 12% a year (95% CI 2-23%; P=0.022) towards increasing breast cancer risk with increasing duration of employment with the ABC. Half the women had breast cancer diagnosed at less than 40 years of age, which corresponded to an SIR for breast cancer at this age of 18.23 (95% CI 5.9-42.5). The affected women had, on average, begun work at Toowong earlier and worked there longer than had other female employees in the study period. They also appeared to have been more likely to work in the newsroom. Relative to Australian women in general, they had higher educational levels, were somewhat more likely to drink alcohol, to have used oral contraceptives and to perform shift work, but less likely to smoke and more likely to exercise regularly. They were similar to other Australian women with respect to age at menarche, childbearing and breast feeding. Only one was menopausal, none had taken hormone replacement therapy and none had a family history of breast cancer. Apart from ionising radiation, which is a well established cause of breast cancer, our literature review found very limited evidence that any other workplace exposures might cause breast cancer. We considered it prudent, however, to investigate the Toowong site and workplace for environmental exposures that are known or suspected to cause any cancer and might plausibly be present there. No historical or other evidence was found of unusual contamination with or exposure to known or suspected carcinogens on the site. Asbestos had been used in construction and insulation of site buildings and had been removed on a number of occasions, including as recently as 1998. Measurements of asbestos in air in the mid 1980s and in 1998 at the time of asbestos removal, however, showed asbestos concentrations of Breast Cancer at the ABC Toowong Queensland - Final Report Page 3 of 75 <0.01 fibres/ml except on one occasion (0.01 fibres/ml). Although broadband measurements of radiofrequency electromagnetic fields on site showed higher than usual levels in a few locations, these were only in close proximity to identifiable sources to which only infrequent or brief exposure would have been likely. Measurements of extremely low frequency electromagnetic fields were similarly unremarkable. Although there was an unusually high level in an equipment room, levels measured at all other locations and individually monitored for several staff members for a few hours were similar to those observed in a small survey of Australian residences and in people without specific occupational exposure in an overseas survey. Levels of possibly carcinogenic elements in the Toowong water supply met Australian standards and measured ionising radiation was at background levels, except for radon levels in the air of the TV building. These mildly elevated levels, however, were measured, unavoidably, after staff had vacated the TV building when the building was closed and the air conditioning turned off. Under these conditions falsely high readings could be produced. These measurements of environmental exposure were inevitably limited to the present; whereas the environment of the 1980s and 1990s, or even earlier, is that most likely to have contributed to breast cancers occurring between 1994 and 2006. Nothing in our inquiries, however, produced evidence to suggest, with the probable exception of environmental tobacco smoke, that there was important past exposure to carcinogens at Toowong that would not have been present in 2006. The Panel concluded that: • There was a real increase in the risk of breast cancer in women working at the ABC Toowong site that was related to length of employment and may have been contributed to by some aspect of work or the working environment at Toowong. • It was highly unlikely that this increase was caused by exposure during work on the Toowong