Dioxin contamination of Great Lakes fish is ``cause for concern,`` but not an immediate health hazard, according to results of a U.S. Environmental Protection Agency study released Monday.
Lake Ontario fish contain the highest concentrations of the chemical that the EPA considers toxic and a potential cancer threat, according to the report. Moderate levels were found in Lake Michigan and Lake Huron fish, while the lowest levels were found in Lake Superior and Lake Erie fish.
Federal officials called their report a ``snapshot`` of dioxin pollution and the most complete so far, comparing fish contamination levels in all five lakes. Their warnings come as the spring sport fishing season swings into high gear.
Valdas Adamkus, the EPA`s Midwest regional administrator, said the findings were not startling or alarming, since toxic chemical contamination of Great Lakes fish is a known environmental hazard and states bordering the lakes have issued health advisories on eating Great Lakes fish.
The EPA considers fish containing more than 5 parts per trillion (ppt.)
of dioxin a potential health hazard.
The $2 million, two-year study is based on fish samples, mostly bottom-feeding carp, at 41 locations in the Great Lakes. It found dioxin levels as high as 30 ppt. In a separate study of lake trout fillets at six locations, dioxin levels reached 41 ppt.
In the Midwest, the EPA found seven waterways where fish contained dioxin levels high enough to warrant concern.
-- Lake Michigan: Grand River, Grand Ledge, Mich.
-- Lake Superior: Superior Harbor, Superior, Wis.
-- Lake Huron: Saginaw Bay, Caseville, Mich.; Tittabawassee River, Midland, Mich.; and Flint River, Flint, Mich.
-- Connecting channels: Detroit River, Trenton channel, Mich.; and Rouge River, Detroit.
In the lake-trout study, highest dioxin levels were found in Lake Ontario, followed by Lake Huron and Lake Michigan. The New York Health Department has advised against eating Lake Ontario trout, and the EPA said the dioxin levels in Lake Huron and Lake Michigan trout are ``cause for concern.`` The extent of health hazards from dioxin concentrations and sources of dioxin contamination in the Great Lakes are not entirely clear, according to federal officials. Sources of contamination could include industrial concerns, including chemical manufacturing plants, that burn dioxin-contaminated material that escapes into the atmosphere and falls back to Earth, agency officials said.
The EPA said it will continue to search for sources of dioxin pollution and act to halt any emissions found. More studies are needed to reveal the full extent of dioxin poisoning in the lakes, the agency said.
Toxic chemical contamination of the Great Lakes is the highest priority of the EPA`s Midwest regional office, Adamkus said. The dioxin study will be submitted to Congress this summer for possible legislation, he added.
Adamkus, the region`s highest EPA official, said it was almost
``irresponsible`` that federal agents cannot agree on a dioxin danger level in food. The EPA is pushing for a 5 ppt action level, some states cite a limit of 1 ppt while the Food and Drug Administration allows up to 50 ppt.
Adamkus said the contamination is not an immediate health problem because dioxin poses a long-range health threat from consumption of fish tainted with very low chemical concentrations over many years.
Dioxin accumulates in the body fat of fish, and is found in the highest concentrations in older and larger fish that feed on other dioxin-tainted fish. States generally warn sport fishermen against eating Great Lakes fish more than once a week, while some states specifically warn against eating certain fish larger than 20 or 25 inches.