In December 2018, The Age reported a potential cluster of cancers on the Bellarine Peninsula purported to be related to historical use of the pesticide dieldrin in the area. Reports detailed a potential class action by those thought to be affected.
Dieldrin is classified as a probable carcinogen (Grade 2A) by the World Health Organisation's International Agency for Research on Cancer (IARC). This is based on 'limited evidence' for breast cancer in humans and 'sufficient evidence' for liver cancer in experimental animals. Specific community concerns were raised about a perception of a high number of cases of non-Hodgkin lymphoma, multiple myeloma, brain tumours and leukaemia in the area.
In response to this issue, the Chief Health Officer initiated a review of cancer incidence rates for total cancers; breast and liver cancer; and non-Hodgkin lymphoma, multiple myeloma, brain cancers and leukaemia.
Whilst current research suggests no association between dieldrin and blood cancers, there was substantial speculation about the high number of cases of these cancers in particular and understandable distress and concern in the local community. This concern was particularly focused on these cancers in young people. This report aimed to provide a comprehensive review of cancer data relevant to the community's concerns.
The primary source of data for this report is the Australian Cancer Atlas, which includes comprehensive cancer incidence data for all of Australia by geographical area.
Analysis of these data indicates:
- no evidence of a higher rate of cancer overall in any geographical areas of the Bellarine Peninsula than elsewhere in Australia
- no higher number of the specific cancers of interest (breast, liver, non-Hodgkin lymphoma, multiple myeloma, brain cancers and leukaemia) than would be expected (based on the average cancer rates in Australia).
Assessment of the available epidemiological data has not found evidence of higher rates of the cancers assessed in any geographical areas within the Bellarine Peninsula. In addition, the hazard of concern (dieldrin) has not been identified as an agent that results in the cancers cited in the media.
Cancer in young people is unusual and particularly distressing. It is often difficult to identify a cause or to find explanation for the illness in children and young adults. Memories of these cases remain deep in communities and families for many years or a lifetime. Nothing in this report is intended to, nor should be taken to, dismiss the reports of individuals with cancers or of those friends and families who are all too aware of the tragedy that these cancers have had on many lives.
This report has examined cancer rates in defined areas known as Statistical Area Level 2 (SA2). This is the appropriate sized area to 'capture' sufficient cases of cancer to avoid the random fluctuation in rates that occurs when looking at smaller areas. As smaller areas and shorter time periods are examined, there is normal variation in cases and rates, due to chance alone. For example, if looking at areas of a few residential blocks, and one or two year time periods, it becomes apparent that there is large variation between areas and over time. Several areas will have no cases; some will have a few; and one or two areas may have several cases. This can sometimes be the basis for concern at an apparent increase in cases that occurs over particular years, or in very localised areas, or in particular age groups.
DHHS and the Chief Health Officer are committed to working with communities and relevant agencies to ensure that community concerns are conscientiously addressed, and that appropriate support and reassurance is provided.
The Chief Health Officer would like to express his heartfelt sympathy to all those affected by cancer on the Bellarine Peninsula and for the distress that concerns of a cancer cluster cause. He welcomes questions about, or critiques of, this report and recommends that anyone who wishes to further investigate the publically available data does so.