"LANSING -- The largest, deepest and coldest Great Lake holds another distinction -- the highest levels of the contaminant toxaphene in the region and possibly anywhere in the world.
Since federal bans on persistent pollutants took effect in the 1970s and 1980s, most chemical concentrations have declined in the Great Lakes.
Some toxicologists say the same is true of the insecticide toxaphene.
But toxaphene levels in Lake Superior have increased by 25 percent since its ban in 1990, according to Mel Visser, of Kalamazoo, a former environmental health safety officer and author of "Cold, Clear and Deadly," a book about Great Lakes contaminants.
Toxaphene has been shown to damage the immune system, nervous system and lungs and to cause cancer. The principal human exposure comes from eating fish."