Water S.O.S Tasmania
Alarm at weed-kill chemical in water | Matthew Denholm - May 15, 2008

AUSTRALIAN regulators have allowed a widely used weed killer to be present in drinking water at levels twice those now shown to cause damaging genetic changes in human cells.

A new study by the University of California, San Francisco, has found atrazine increases activity of human genes linked to fetal growth retardation and infertility. Atrazine is used to control weeds in forest plantations and crops such as canola, sugarcane, maize, sorghum and lupins across Australia.

Holly Ingraham, study senior author and UCSF professor of cellular and molecular pharmacology, told The Australian significant effects on human placental cells were seen when exposed to as little as 20 parts per billion of atrazine.

This is half the 40ppb atrazine health value limit under the Australian Drinking Water Guidelines. The US has a drinking water maximum of 3ppb for atrazine, while Europe has refused to approve it for use.

Professor Ingraham said as a scientist she had "no agenda" in terms of regulation, but she believed Australia's health value of 40ppb was "worrying".
"If it were me drinking water, I would want it as low as possible," she said.

The study also exposed zebrafish to the chemical, finding significant effects at 2ppb and changes to sex ratios at 20ppb.

Earlier this month, the Australian Pesticides and Veterinary Medicines Authority announced its review of atrazine had concluded "no changes to the existing health standards" were needed.

This was because while atrazine had been shown to disrupt the nervous, hormone and reproductive systems of rats, it was "unlikely that atrazine is an endocrine (hormonal) disruptor in humans".

However, the UCSF study drew the opposite conclusion. "Our results strongly suggest that atrazine is an endocrine disruptor - it is indirectly estrogenic, and it most certainly has the potential to influence reproduction, as well as other endocrine functions," Professor Ingraham said.

Endocrine disruptors affect the body's hormonal system, potentially affecting growth, development and reproduction.

"Would a fetus or child be especially sensitive to this herbicide? Probably. Our study shows that some of the genes targeted by atrazine have already been linked to intrauterine growth retardation and infertility."

APVMA public affairs manager Simon Cubit said the regulator's decision not to toughen atrazine restrictions was based on "weight-of-evidence" from many studies.
However, APVMA had sought expert advice from Australia's Office of Chemical Safety and drawn its attention to Professor Ingraham's study.

The Health and Medical Research Council said it would consider "all the latest evidence" as part of its review of drinking water guidelines.

Atrazine producer Syngenta did not comment but has insisted the product poses no risk to human health.

Tasmanian GP Alison Bleaney, who believes atrazine may be linked to high rates of cancer and auto-immune disease, demanded an urgent regulatory rethink.

"One would hope that our regulators would be protecting us and protection means occasionally that you have to take a stand on the balance of probabilities," she said. "And the balance of probabilities has shown for some years that atrazine is not a safe chemical to have in our environment."