DIOXINS are a group of persistent organic pollutants.

They are contaminants in many petrochemicals including now banned pesticides such as the notorious defoliant Agent Orange [245T].

Dioxins are said to be the most poisonous chemicals that we’ve managed to produce. Toxicologists call them ‘slow poisons’ because their effects follow accumulation in the body over time through consumption of contaminated foods. 

They are associated with immune system problems and some forms of cancer, particularly soft tissue cancers. Nursing mothers can transfer these fat-soluble chemicals in breast milk that can affect early childhood development of children.

In January 2006, the NSW State Government banned commercial fishing in Sydney Harbour.  Fish and prawns from the harbour were found to have dangerously high levels dioxins — the legacy of decades of industrial pollution upstream at the now demolished Union Carbide plant at Homebush Bay.

Fishing has long been banned in Homebush Bay, but at nearby Silverwater tests of bream revealed dioxin levels eight times safe eating levels; 9 km downstream at Drummoyne, school prawns were more than three times over the limit and 23 km from Homebush at Rose Bay, not far from the open ocean, a squid tested to be more than 1.5 times safe eating levels. There are only two other aquatic studies elsewhere in the world that had higher dioxin levels than Sydney Harbour, they were in New York and Rio de Janeiro.

Poisoned by dioxins

In January the NSW State Government warned the public it was not safe to eat more than a mere 150 grams of Sydney Harbour seafood each month; the equivalent of just one fish finger a week. Despite this warning, the State Government ignored repeated calls from the harbour fishermen for blood tests to assess whether they, too, have been poisoned by dioxins.

The ABC 7.30 Report commissioned dioxin blood tests on two commercial fishers and two family members; all had levels that exceeded the average adult dioxin level and in one individual — the oldest man — tenfold.

In the space of 24 hours, political indifference turned to action. The NSW Government will now offer free blood testing to all commercial fishermen and their families who want them.

This expose once again highlights the need for baseline surveys for dioxin exposure amongst high risk groups in our society and particular foodstuffs that could contain these pollutants.

A failure to undertake surveys

It should be ringing bells in all jurisdictions. There has been a failure to undertake comprehensive chemical residue surveys of people who would be at high risk — through years spent eating potentially contaminated foods.

A recent international survey of salmon products highlighted the levels of persistent organic pollutants like polychlorinated bipenyls (PCBs), organochlorines and dioxins in these foods; commercial salmon produced in Australia was not part of the survey.

Those pollutants are in Tasmania’s ecology.

This was borne out in a small survey of Tasmanian platypus in 1998 that detected high levels of PCBs and DDT in the body fat of these free-living aquatic mammals.

This is worrying because DDT was officially phased out in Tasmania in the early 1980’s. Despite this, non-metabolised DDT was still present in platypus in the late 1990’s. The concentrations of DDT found in Tasmania platypus were similar to levels reported in wild mink in Europe in the early 1980’s. A small survey but one that warranted further action.

As Tasmanian anglers will confirm trout and salmon live along side Tasmanian platypus and their position in the food chain make both the fish and the monotreme equally likely to bio-accumulate these pollutants.

There is a duty of care and probably legal responsibility that all Governments have to their citizens to identify potential toxic risks based on adequate environmental testing.

As with asbestos and lead-related health issues — the ‘absence of evidence’ should be no excuse for apathy and indifference.

Pictures: Ukrainian President Viktor Yushchenko, before and after dioxin poisoning.