DDT floats in Ord River 40 years after last use
Testing for pesticide contaminants in the Ord River has only been carried out once, despite the widespread use of organochlorine pesticides such as DDT in the area between the 1960s through to 1979.
Questions about the current state of the Ord River Irrigation Area (ORIA) put to the WA Parliament last month revealed that while the ORIA is tested every four weeks for contaminants, the Ord River has only been tested for pollutants like DDT once – over a decade ago.
A 2008 study by the Department of Water reported that prior to 1974, 128 tonnes of the organochlorine DDT were used on crops across the ORIA.
In the 1960s, farming crops irrigated in the ORIA were sprayed with several pesticides which are now banned in Australia due to their disastrous effect on the environment.
The collapse of the cotton industry resulted in the end of the widespread use of these pesticides prior to their ban.
As of 2008, trace amounts of these now banned pesticides were still present in animals and plants, with the most commonly detected being DDT and dieldrin.
Traces of DDT were most commonly detected in fish samples and carnivorous animals with high fat levels, such as water monitors and turtles.
Of the fish samples taken in the study – all had high trace amounts of DDT in the fatty tissue and one exceeded the threshold set by Food Standards Australia New Zealand (FSANZ) for edible offal.
The study also found a goanna with detectable levels of a DDT-related pesticide, last used in the Ord in the late 1970s.
The highest concentration of dieldrin was detected in wallabies, with the sample containing over 160 times the reference sample (350 nanograms per gram to 2.1 nanograms per gram).
Based on the trace pesticides detected, the Department recommended people avoid eating large quantities of fish offal caught downstream from Diversion Dam as well as limiting the consumption of high fat carnivorous animals to avoid contamination.
This poses significant health risks for Aboriginal people still living on country and off the food the bush tucker that the land provides.
General publicity of this information has been limited and is not common knowledge for people living in the area.
DDT is a known endocrine disruptor, a chemical that can interfere with hormone systems in the body, and has been linked to cancer in humans.
A study published earlier this year in the Journal of the National Cancer Institute revealed people exposed to DDT have an increased risk of developing breast cancer – even four decades after first exposure.
There was no clarification by the WA Government as to whether issues evident in the 2008 report have since been resolved or if continual testing of the Ord River will be considered.
By Hannah Cross