A surge in cancer and neurological cases in north-eastern Tasmania since 2002 is consistent with chronic low-level chemical exposure, says a report to be submitted to the federal Australian Medical Association next month.
The Tasmanian AMA has charted the rise for the first time and wants expert opinion from the AMA’s public health committee. The report says Tasmania has health anomalies including a sudden jump in childhood cancers and higher-than-average premature births. Its says cases documented around St Helens, on the east coast, in particular are symptomatic of possible chemical exposure.
The report says a rise in neurological illnesses, reproductive and gastrointestinal cancers around St Helens is statistically significant over and above what might be expected through population increases alone. The rise coincides with the expansion of timber plantations in the catchment that supplies the drinking water.
Plantations are sprayed with chemicals during establishment to kill weeds and grasses. The local Break O’Day Council, helicopter operators, the Health Department and the Department of Primary Industries, Water and Environment have identified at least a dozen herbicides in use or detected around St Helens since 2002. Many are known as possible carcinogens or hormone disruptors.
Tasmania’s Director of Public Health, Dr Roscoe Taylor, said cancers and other health conditions around St Helens did not appear to depart significantly from the rates expected in a population with similar demographics. The department has sought independent toxicology advice on the neurological cases and expects a report in a fortnight.
The Tasmanian AMA president, Launceston-based Dr Michael Aizen, said the Government response in investigating chemical use and testing water was inadequate, and data available was limited. He wanted more robust, transparent water testing that correlated with when, where and what chemicals were applied.
Stan Siejka, northern Tasmania’s only neurologist, said that in the past year he had treated several patients with unexplained neurological symptoms and definite exposure to chemical spraying. In a typical case, a worker showed classic symptoms after a field nearby was sprayed, but his employer called Dr Siejka to claim the worker had not been exposed.
“I don’t like to see this complete denial where there is a clear possibility that he could have been exposed,” Dr Siejka said. “The frustration is we have little access to what precisely has been applied in the area, and it is very difficult to get independent assessments for the concentrations. A lot of the chemicals are known to have potential side effects.”
Chemicals identified in the St Helens catchment included atrazine and simazine, classified by the World Health Organisation as Type 2B carcinogens, meaning they are suspected of causing cancer.
Atrazine is readily absorbed through the gastrointestinal tract, according to a draft review released in October last year by the Australian Pesticides and Veterinary Medicines Authority.
The review says atrazine, when properly used, is unlikely to pose an unacceptable risk to human health. However, it also noted the chemical was moderately toxic to creatures at the bottom of the food chain, including algae and tiny marine crustaceans. Overall, it said atrazine was slightly to moderately toxic to humans and other mammals.
Break O’Day Council began monthly water tests for chemical residues in July last year. The Health Department ordered tests following a community outcry over the failure to clean up chemical spilt in a helicopter crash in November 2003.
Two months later, more than 90 per cent of oysters downstream in Georges Bay died after a flood.
Break O’Day Mayor Stephen Salter said no chemicals had been detected so far and the water supply was safe. The council is sampling from the George River just above its entry into Georges Bay, where dilution is maximised. The St Helens town water intake is several kilometres upstream.
Alison Bleaney, the St Helens general practioner who alerted health authorities to apparent anomalies in illness rates, said the council and other agencies were using methods to detect individual chemicals and bacteria, rather than testing whether the water itself was toxic and then investigating possible cause.