CRC CARE, Science Alert 27 Sep 09;
Governments worldwide need to move with urgency to tackle the mounting risk to human health posed by the cocktail of toxic contaminants in our living environment, a leading scientist has warned.
“Heath Ledger and Michael Jackson both died from mixtures of drugs, not from single drugs. Their cases are a warning of what can happen when you take in two or more toxic substances,” says Professor Ravi Naidu, convenor of the global CleanUp 09 conference which opens in Adelaide tomorrow.
People living in both urban and rural environments around the world are increasingly exposed to toxic mixtures of heavy metals and organic chemicals such as pesticides, PCBs and VOCs in their food, water, air and soil – yet most governments continued to address the problem one chemical at a time, Prof. Naidu, the managing director of CRC CARE, says.
“In contaminated sites we are almost always dealing with mixtures. As we see from the cases of Ledger and Jackson, combinations can sometimes be far more deadly than individual substances.
“It makes far better sense to assess the risk to human health posed by the combined contaminants, than to look at them one by one.”
This meant assessing not only the mixture of chemicals, but which parts of it were capable of reaching the public via the food chain, water, air or dust, and the combined health effects this might have.
This issue, known as bioavailability, represents another huge challenge for the environmental clean-up sector worldwide, Prof. Naidu says.
“Bioavailability means establishing whether or not the toxic substance can actually reach you. In some cases it can – and in others, for various reasons, it can’t. The sites we ought to clean up as a priority are the ones where the toxins are available to reach the public and environment.”
However most environmental agencies the world over still insist on cleaning up sites where contaminants have been found, even if the contaminants are safely locked up in the soil and unable to reach the public. This wastes money, delays economic development and causes unnecessary concern to the community, he says.
A third major challenge was to stop trying to solve the problem of pollution simply by moving it somewhere else, to become a threat to future generations.
“Many countries, including Australia, are still trying to solve the problem of contamination by digging up toxic waste and polluted soil and dumping it in landfills on the urban fringe.
“Years later the city has expanded, these toxic dumps have become part of the suburbs, and their contents again threaten to the health and safety of the community.
“You cannot overcome pollution merely by moving it. You have to disable it.
“Dig-and-dump is not an answer to the problem of contamination, and needs to be replaced by approaches which involve turning the toxic substances into forms which are completely safe, or locking them up so they become unavailable to harm anyone.”
Professor Naidu says Australia has been slow to adopt best practice in risk assessment and clean-up, in part because the States still had widely different approaches to the issue.
“Overall, there has been a lack of progress in addressing the issue of contamination and using the latest scientific methods for dealing with it. Although we have excellent National Environment Protection Measures (NEPM), we are not working together at the practical clean-up level as well as we should.
“We are not properly addressing the question of multiple contamination, the issue of bioavailability or the need to move away from dig-and-dump to safer, more sustainable methods.
“It is time we did.”
