Toxic PCBs are widely found in the Great Lakes at levels 100 times higher than what's safe for human health, says the Canada-U.S. body overseeing the lakes. "We're talking about the general water quality concentrations (in) lakes Ontario, Erie, Michigan," said Michael Gilbertson, a biologist with the International Joint Commission.
Gilbertson said "thousands of people" continue to eat dangerous amounts of tainted fish after years of warnings, and damage the health of their babies while they're in the womb. The damage from "gender-bender" chemicals that imitate human hormones includes loss of intelligence, behavioural problems, weakened immune systems and other problems. "Subtle but significant effects are going on with these children, which seem to be irreversible," he said. A new report from a board of scientists who advise the IJC says the lake water, despite 20 years of improvements, still has "persistent toxic substances in fish and wildlife at concentrations that pose threats to human health." PCBs, a now-banned industrial oil once widely used in electrical transformers, continue to be a major problem, the science board says. Its report says today's official safe limits for PCBs are probably enough to protect people, both from cancer and damage to fetuses.
Then it drops this bombshell: "The available environmental monitoring data indicate, however, that the present concentrations of PCBs in samples of Great Lakes water are about a hundred times higher than these criteria. "In some cases these concentrations are associated with actual effects on the more highly exposed individuals in critical subpopulations." That's the scientific way of saying groups of people who eat lake fish -- urban poor people, immigrants from countries where fish is a staple, and the families of sport fishermen -- are already suffering health damage that can never be cured. Two long-running studies followed children of American women who ate fish from Lake Michigan (beginning in the early 1980s) and eastern Lake Ontario (beginning in 1990). As newborns, they startled too easily and had trouble getting used to their surroundings. Later the children continue to score below average on intelligence tests and have learning problems and poor motor skills. All it takes is one or two meals of lake fish a month for the chemicals to build up in a person's body. Health surveys among fish-eating people in both Canada and the U.S. found: o Bangladeshi immigrants who fish in the St. Lawrence River eat an average of 48 sport fish meals a year, while Vietnamese immigrants in the same area eat 47. o Black women near Lake Michigan continued to eat contaminated fish from the lake through their teens and 20s, which allows chemicals to build up in their bodies and eventually be passed on to their babies.
Their breast milk was also high in PCBs. o A survey of more than 3,700 Canadians fishing on official "toxic hot spots" such as Toronto and Hamilton harbours found many didn't stick to guidelines on which fish were safe to eat.
Some also ate more fish than was safe. o As Mohawk men in New York State ate more St. Lawrence River fish, the levels of PCBs in their blood rose. While PCBs come from old industrial waste dumps, Gilbertson said, "the waters are moving around the lakes, so these are general concentrations out there." The amounts involved are tiny: The safe limit is just 17 trillionths of a gram of PCB oil in a litre of water. And water itself is safe to drink. The trouble comes when PCBs build up in the tissue of fish, and people eat the fish.
Governments have made big investments in cleaning the soils and sediments where old PCBs leaked or, more often, were dumped. A 1999 summary from the IJC notes a variety of U.S. agencies spent $12.75 million US dredging tainted sediments from the Rouge River, near Detroit. They took out 434,000 cubic metres of soils and sludge. Other sediments cleanups include $13 million US on sediment in Ohio's Ashtabula River, which flows to Lake Erie; $9.3 million in Thunder Bay harbour; and one of the largest, more than $300 million US, still under way on the New York shore of the St. Lawrence River across from Cornwall. But the contamination hasn't gone away. The solution remains the same as ever, Gilbertson says. Clean up the old sediments, "but not only that -- also trying to move on to the long-range transport of these pollutants" that drift hundreds of kilometres in the air before falling in rain and snow, he says.
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