Water from rivers on Tasmania’s north-east coast is toxic to sea urchin larvae, a species used in European research as a model for pre-cancerous changes in human cells. Larvae cells dies in surface water samples taken from rivers with suspected chemical contamination. Oyster larvae cells also died or failed to develop normally.
Sea urchin cells are recognised as models for cellular development in all living things. Dysfunctional development is a hallmark for tumour cells and human cancers, according to French studies cited in a report prepared for the Australian Medical Association.
The AMA’s public health committee will consider the results at the end of the month, along with statistics from the Tasmanian AMA branch that suggest increased occurrence of neurological illnesses, intestinal tract tumours and reproductive cancers in northern Tasmania.
The Tasmanian AMA prepared its report following community concerns that health problems may be linked to chemicals used in forestry. The rise in illness coincides with the expansion of plantations, which have more than tripled in areas across northern and eastern Tasmania since 1996.
Timber plantations undergo chemical treatment in the first few years to remove competition from wildlife, plants and insects that might slow growth rates. Chemicals used include atrazine, a possible human carcinogen, and alpha-cypermethrin, which is toxic to oysters in trace quantities.
Tasmania’s public health director, Roscoe Taylor, said the tests using sea urchins and oyster larvae were not relevant to drinking water standards for humans. “No other regulatory or water authority in Australia has been in the practice of using these tests,” he said. The method could concentrate naturally occurring toxins, such as tannin, “so it is very premature to declare human health risks in relation to man-made toxins”.
He said the tests had been referred to the Department of Primary Industries, Water and Environment. The department would try to reproduce the sampling and conduct similar tests at other sites. “It is interesting stuff, but premature to speculate publicly about the risk to public health,” Dr Taylor said.
St Helen’s oyster farmers first raised concerns about chemical contamination after 90 per cent of their oysters died in January last year following a record flood. The Department of Primary Industries, Water and Environment says fresh water killed the oysters.
A marine ecologist at Sydney Water, Dr Marcus Scammell, investigated on behalf of the farmers and said fresh water alone could not explain the death rates. Break O’Day Council has tested water in the George River, near St Helens, monthly since July last year. The results have been clear, but Dr Bleaney said the issue was the cumulative risk, not whether particular chemicals could be detected. She said many studies indicated chemicals acted in concert in the environment to harm human health.
Dr Scammell said European researchers used urchin cells as a predictor for tumour development in humans. He said Tasmanian authorities should suspend risky activities pending an investigation, and should test water to isolate what was harming the larvae. “Something is causing mortalities in oysters that are unnatural, and something is causing a significant effect on human health since mid-2001, he said. “We would put a halt to everything until we had worked out what the hell was going on.”