No smart Torontonian would drink a glass of water straight out of Lake Ontario. But although we all know the Great Lakes are polluted, we don’t really know what chemicals are in there, and what’s being done to control them.
Dr. Gail Krantzberg, the director of McMaster University’s Centre for Engineering and Public Policy, spoke last Thursday about toxic substances in the Great Lakes. The contaminants aren’t new, but many are only now being identified as threats.
One class of chemicals falling under scrutiny are polybrominated diphenyl ethers, a type of flame retardant used in commercial products like furniture and electronics.
“They’re in the carpets, they’re in your clothes, they’re in the walls. They’re fire retardants and they’re there to protect society,” Krantzberg explained. But they may pose a risk to society as well. Krantzberg said that PBDEs have been shown to cause neurological impairment and hormone disruption in humans.
These effects are very similar to the effects of banned PCBs, a previous generation of fire retardants. According to Krantzberg, this should come as no surprise, because PBDEs are chemically similar to PCBs. Both elements are members of the halogen family and have similar chemical properties.
Krantzberg said that inventing new flame retardants “isn’t a question of tinkering with the substance to make it a little different, but requires innovation.”
One characteristic that makes many of the Great Lake pollutants so dangerous is their ability to bioaccumulate. Substances that dissolve in fat are not easily excreted from organisms, and so remain in the bodies of animals that ingest them. As predators consume more and more contaminated plants or animals, they suffer the cumulative effect of toxins stored in their prey’s bodies. Animals at the top of the food chain therefore most threatened by bioaccumulation.
Of 11,000 chemicals in the Great Lakes recently screened by the Canadian Environmental Protection Act, over 20 per cent of them were highly bioaccumulative.
What can be done about these newly discovered threats? One major avenue for change is legislative policy. Krantzberg feels that legal documents currently under revision, such as the Great Lakes Water Quality Agreement, should require more precautions when dealing with chemicals whose pollutant effects are yet unclear. The “precautionary principle,” an environmental concept currently popular among European policy-makers, states that “the lack of scientific evidence shall not impede policy development to be protective of present and future generations.”
“Clearly precaution is better than cure,” Krantzberg said. She urged Canada to eliminate substances that show detrimental effects in laboratory animals and that have potential-even unproven-toxic effects.
Calling for a radical shift in regulatory policy, Krantzberg said that the current system of banning chemicals only after they are proven hazardous must be reversed. According to her, we need to put “an onus on industry to demonstrate no harm, rather than on government to prove harm.”
