by Tom Spears
The Ottawa Citizen September 23, 1999
"Gender-bender" chemicals in the Great Lakes that mimic human hormones are derailing women's menstrual cycles and making couples infertile, a new Canada-U.S. report says.
"The physiological effects are manifested at very low doses that in the past were considered safe," the report from the International Joint Commission says.
Years of traditional toxicity tests, in which rats or fish are fed high doses of chemicals, appear to be missing a crucial point, the report says.
That's because animals recognize hormones only in small doses. A pollutant that mimics a hormone will trigger a response only if it arrives in the body in the tiny quantity the body's receptors expect.
"Effects (on health) appear at low doses that do not appear at high doses," the report says, because receptors in the brain "shut down" when a high dose of a chemical arrives.
The Atlantic Salmon Federation has reported the same trouble in young salmon on the East Coast.
Its research has shown that the salmon don't react to heavy doses of "gender-bender" pollutants in lab tests, but do react to the smaller amounts found in rivers.
The IJC is a Canada-U.S. body advising both countries' governments on the lakes. It is playing host to a meeting of scientists, activists, governments and industry this weekend in Milwaukee, an event held every two years to discuss the state of the lakes.
Lake pollutants have been known to hurt wildlife for decades, often by undermining their reproductive systems. Now the fake hormones are emerging as dangers to humans as well -- and in previously unsuspected ways:
l Women's and men's reproductive systems alike are skewed. "In one study being undertaken in New York State, there is a significant reduction in the timing of the menstrual cycle in women who consumed more than one meal per month of contaminated fish from Lake Ontario," the report says.
l Couples in Michigan who eat fish from the Great Lakes are showing a high rate of infertility. Of 625 married couples in the Michigan study, 15 per cent had no success after one year of trying to conceive. Though that rate in itself isn't unusual, the study found the couples with the greatest trouble conceiving were the ones in which the men ate the largest amount of contaminated Great Lakes fish.
l Chemicals consumed by women before or during pregnancy damage their babies in the womb. A multi-year study of children of mothers who ate fish from Lake Michigan, born in the 1980s, shows they now score an average of 6.2 points lower on IQ tests than children of mothers who didn't eat the fish.
The report says a second group of New York State children, whose mothers ate Lake Ontario fish, show similar problems in intellectual development and behaviour.
l Inuit children, who eat even larger amounts of similar chemicals from Arctic fish and game, suffer hearing loss. The report says a type of PCB (a now-banned industrial oil once used in electrical equipment) inhibits the body's hormone thyroxin, which helps the ear develop.
"There is no doubt, based on the Great Lakes monitoring data, that the levels of persistent toxic substances have declined in the past 30 years," the IJC report says. "However, there has been an increasing knowledge of the dangers posed by exposures to these substances."
"All the recent scientific evidence supports the need for elimination" of key pollutants, said John Jackson, former president of Great Lakes United, a Canada-U.S. coalition of residents and environment groups. "Tiny, minuscule quantities are having dramatic impacts."
But he said Canada's main law on toxic wastes, the Canadian Environmental Protection Act, "does not go down that path. It doesn't require elimination."
The law instead puts limits on pollutants without saying the most toxic ones must be eliminated completely.
A recent Citizen series showed how major Canadian industries weakened the law by telling the federal cabinet that fighting pollution would close factories and throw people out of work.
Many of the lakes' pollutants won't make people die earlier, but will cause other forms of health damage such as infertility, reduced intelligence or weak immune systems, the report says.
"There appears to be no threshold (i.e. safe level) at which they do not effect a change," the report says.
People most exposed to the chemicals are poor people in urban areas, native people, sport fishers and some immigrant groups that rely on fish, such as the Vietnamese.
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