The report says that while contaminants have been reduced in parts of the Great Lakes, severe problems remain, particularly for Lake Ontario's fish, which have been the subject of an increasing number of advisories recommending reduced consumption. Contamination levels are also worrisome in Lake Huron and many pockets of unsafe-to-eat fish remain in Lake Erie and even Lake Superior, the least polluted of the Great Lakes.

The fish species reviewed included coho salmon, rainbow trout, walleye, pike and lake trout.

"The trends in fish consumption advisories clearly indicate that the lakes continue to be polluted to such an extent that human health is threatened," the report said, calling for steps to reduce pollution emissions significantly in the Great Lakes basin and deal with the continuing legacy of dangerous chemicals, such as PCBs. Even though PCBs, once used in electrical equipment, were banned in the 1970s, they are still being found in some fish at unsafe levels.

The report was based on a comparison of a Ministry of Environment recommendation on the safety of various types of fish issued in 2005, and another released earlier this year.

But the ministry rejected the report's conclusions. Spokeswoman Kate Jordan said the amounts of contaminants found in fish have generally been falling. However, she said the province has recently applied more rigorous federal exposure standards for PCBs and dioxins in determining how much fish it is safe to eat.

The report says it doesn't want to discourage people from eating fish, which are high in protein recommended by many health experts, but wants to highlight the need for continuing action to reduce discharges of harmful chemicals into the water.

"Fish advisories due to damaging levels of toxic contamination in Great Lakes fish serve as a potent warning that to safeguard the Great Lakes as a vital resource and international treasure, we must dramatically reduce pollution in the basin," it said.