Dioxin in Great Lakes Suspected in Trout Deaths Starting in 1940’s 

AP 26oct 97

Scientists tested core samples drilled from the bottom

TORONTO -- Dioxin may have started killing lake trout in the Great Lakes more than 50 years ago, Scientists say.

Overfishing and sea lampreys have long taken the blame for decimation of the lake trout population. But anglers and the lamprey - - an eel like parasite accidentally carried to the Great Lakes from Europe earlier this century - may be off the hook.

Researchers have commonly re rejected chemical pollution as a reason for shrinking take trout stocks, biologist Michael Gilbertson said Friday.

Gilbertson works for the International Joint Commission, the Canada-U.S., agency responsible for monitoring water quality in the Great Lakes.

The shift in thinking came from U.S. research by scientists at the Environmental Protection Agency and University of Wisconsin.

Scientists tested core samples drilled from the bottom of Lake Ontario that exposed layers of sediment deposited as far back as 1940, Gilbertson said.

Dioxin, the deadly toxic chemical, was discovered at levels 2.5 times higher than the amount considered deadly for lake trout eggs and embryos. Gilbertson said.

Lab tests showed trout eggs would die when exposed to minute traces of dioxin at levels of 35 parts per trillion and embryos would wiped out at an exposure level of 100 ppt said.

Gilbertson's revelations come as the I.J.C. prepares for a two-day public meeting next weekend end in Niagara Falls, Ontario, to hear concerns about the effects of Great Lakes water pollution.

The commission makes recommendation to the federal governments in Canada and U.S. and for years has urged both to become more aggressive in cleaning up the worst of toxic chemicals in the lakes.

"Will these new pieces of evidence change the political and regulatory process?" Gilbertson asked.

Not likely, says Paul Muldoon, a lawyer with Canadian Environmental Law Association. "The governments have lost their interest in Great Lakes." Muldoon said. "Clearly the Great Lakes are at risk. They have not been at top of the agenda of the governments."