Economy
New study queries pesticide safety levels. State land and waterways ‘still poisoned’
Pesticides could be damaging river biodiversity at levels that have been traditionally regarded as environmentally safe by authorities, suggests a new study.
Ecotoxciologist Dr Ben Kefford, of University of Technology, Sydney, and colleagues, report their findings online in Environmental Science & Technology.
“Pesticides are having an effect at 10 to 100 times lower concentrations than traditionally thought,” says Kefford.
He says when authorities try to protect our streams and rivers from pesticides they rely on thresholds, under which it is assumed pesticides have no effect.
For example, the European Union recommends the use of a commonly-used safety factor of 100.
This means if a negative effect on an aquatic organism is only seen at a particular concentration of pesticide, then a safe level of that pesticide is regarded as being one hundredth of this concentration.
But, says Kefford, the latest evidence suggests that this safety factor is too small.
The evidence comes from a review of eight field studies which took place in Australia, Europe and Siberia.
Each study looked at the relationship between pesticides and the health of aquatic invertebrates such as insects, worms, crustaceans and snails that make up a key part of river ecology.
The researchers focussed on species that are physiologically sensitive to pesticides, and those that are long-lived and find it hard to ‘bounce back’ after pesticides are flushed into the river.
It found that when a safety factor of 100 was used for the most toxic of pesticides, there was a 27 to 61 per cent reduction of these species.
Their study also found pesticides also slowed the breakdown of leaves, which feed river ecosystems.
Kefford says a safety factor of 100 is not protective and leads to changes in river biodiversity and ecosystem functions.
He and colleagues recommend the use of a safety factor somewhere between 1000 and 10,000.
Read the full story, with full links here
• Earlier on Tasmanian Times:
Pesticides and the South Esk River
• Pesticides and Melbourne’s drinking water: new report
First published: 2012-06-04 04:09 AM
• TOXIC CHEMICALS STILL POISONING STATE’S LAND AND WATERWAYS
Tim Morris MP
Greens Water spokesperson
Thursday 7 June 2012
The Tasmanian Greens today said that they were dismayed that chemical trespass, causing chemical contamination of the State’s waterways, was alive and kicking.
Greens Water spokesperson Tim Morris MP said Tasmania’s land, waterways and the ecosystems they are part of continue to be poisoned by toxic chemicals.
“We need to be clear: these chemicals are poisonous and they continue to poison not just Tasmania’s land, waterways and ecosystems, but they are poisoning the state’s world-class and valuable ‘clean, green’ brand too,” said Mr Morris.
“The Department of Primary Industries, Parks, Water and Environment’s latest waterway test results are significant for the information they don’t include as much as the information they do.”
“It is clear that more needs to be done to track chemical pollution back to its source. The Greens’ proposed Chemical Trespass legislation proposes to shift the emphasis of responsibility back to the perpetrator.”
“The State must ban the use of triazines, including simazine, which are some of the most toxic and noxious chemicals. We need these out of our waterways and off the land right now.”
“We are seeing the same waterways consistently appearing on these tests, year on year, such as Tuckers Creek.”
“The Department needs to do more to tackle chemical trespass, such as helping educate users on, for example, how to minimise use and restrict it from trespassing into waterways.”
“Testing is good but acts only to monitor the problem without the necessary action to prevent this contamination happening again and again.”
“The Greens’ Chemical Trespass legislation would go a long way to fixing the issue.”
“The Greens call on the Government to pro-actively disclose the results of all Follow-up Investigations so that we might start to learn why contamination events are occurring and who is causing them.”
“The issue is not about whether or not the levels detected exceed guideline drinking levels, it’s about the fact that our rivers are being contaminated with toxic chemical cocktails, and continue to be contaminated.”
“Any detection of poisons in our rivers is a failure of the regulations and should be treated more seriously.”
“Without a serious effort to trace these contamination events back to their source the problem is only going to continue. Until that happens, the Greens will continue to campaign against the poisoning of our state,” said Mr Morris.