Still permitted for horticultural use in Australia to control insects and mites, endosulfan has been banned in more than 50 countries, including all 27 members of the European Union.

In January, New Zealand banned the pesticide's use and farmers were given 12 months to surrender stockpiles.

In April, the US Environmental Protection Agency began public consultation to consider a similar ban.

Australia's National Toxics Network has amassed research that has linked endosulfan to breast cancer, immunosuppression and birth defects.

The organochlorine compound is suspected of disrupting the endocrine system. It persists in the human body and is passed to the next generation across the placenta and in breast milk.

Endosulfan contamination has not been ruled out as a possible cause for two- and three-headed fish found in the Noosa River this year.

Next month, the Stockholm Convention on Persistent Organic Pollutants, to which Australia is a signatory, will consider moving towards a gradual global ban.

Despite growing opposition to endosulfan's use, however, the Australian regulator, which is funded by agribusiness , has resisted persistent calls for a national ban.

Although a 2005 review by the Australian Pesticides and Veterinary Medicines Authority imposed new restrictions and conditions, endosulfan is permitted for use on a wide range of crops, based on safety data compiled by the EPA in 2002.

Now research from the University of Pittsburgh has found serious flaws in the methodology the US regulator used to test endosulfan's safety risk.

The four-day testing period the EPA used failed to account for the toxin's long-term effects, the University of Pittsburgh researchers concluded in the September edition of Environmental Toxicology and Chemistry. When tracked for an additional four days after the exposure had finished, the new research found a mortality rate of between 50 and 97 per cent.