WASHINGTON - A joint U.S.-Canada commission said Wednesday that mothers who live around the Great Lakes need to be clearly told what kinds of fish are contaminated and what damage invisible, tasteless toxins can do to a developing fetus or a young child.

The International Joint Commission said the eight Great Lakes states and two lakeside provinces haven't targeted their fish consumption warnings to the families that make sport fish a large part of their diets.

The warnings "are not clear enough and they're not getting to the people that need the information," said Thomas Baldini, who heads the American section of the body that oversees the shared waterways.

A particular frustration, he said, was the states' preferred method of distributing the advisories: as another piece of information included with a fishing license.

If the family member who catches the fish isn't the one who cooks it, those warnings often get lost, said Commissioner Alice Chamberlain.

"We need a simplified, clear warning in the case of children and women of child bearing years," she said.

Dr. David Carpenter, a public health physician and researcher at the University at Albany, said studies done in Lakes Michigan and Ontario showed behavioral changes and reductions in intelligence in the children of women who ate contaminated sport fish, and a reduction of thyroid function in children who consumed contaminated fish.

Some of the substances that move from fish flesh to human tissue can remain in the body for years. "What a child eats at the age of six, at least half of it can be passed on to that young woman's child years later," Carpenter said.

At the Michigan Department of Community Health, spokeswoman Geralyn Lasher said that state already is trying to get warnings into the hands of lower-income subsistence anglers, Native Americans and other groups that tend to eat a lot of sport fish.

"We distribute the advisory to all local health departments, WIC (women, infants and children) clinics, doctors offices and many other locations," she said.

Ohio Department of Health epidemiology investigator Robert Johnson, whose area of expertise is fish, said that state is working with WIC groups and the Ohio Environmental Council to try to distribute more copies of the fish advisory and a toll-free information number, 1-800-755-GROW.

State officials began looking for more ways to distribute their warnings after reading studies that showed women tended to do less of the fishing and have less awareness of the contamination advisories, Johnson said.

"I would describe what we're doing as a work in progress," he said.

Contaminated fish warnings tend be complicated lists or charts, which attempt to map, among other things, whether fish from slightly polluted waterways can be eaten often, occasionally or never.

The warnings distinguish between big fish and little fish, but there's no uniformity from state to state except for PCB contamination.

For all other chemicals, "it's up to the state to devise whatever testing protocol, sampling protocol, risk assessment/risk management numbers that they want to devise," said Eric Uram of the Sierra Club Great Lakes Program.