MPCA releases analysis on 50 lakes; DEET, cocaine found

Man-made chemicals, from cocaine to DEET to pharmaceuticals, are finding their way into Minnesota lakes in ways that no one understands, according to an analysis released today from the Minnesota Pollution Control Agency.

Fifty lakes analyzed last year by state scientists contained at least some of 125 different chemicals. DEET, the insect repellent, was the most common, found in 76 percent of them.

Only three of the 50 lakes were chemical-free.

Plastic byproduct Bisphenol A was found in nearly half of the lakes analyzed and cocaine was found in a third. The researchers said some of their findings were “perplexing.”

“The means by which many of the contaminants detected in this study are entering most lakes is not entirely clear,” they said in the report. “The lack of obvious, proximate sources of contaminants, or evidence of recreational use or other human presence, makes it difficult to understand the mechanisms by which pharmaceuticals, personal care products, or other chemicals enter many of these lakes.”

For example, carbadox, a veterinary antibiotic approved only for use in the rearing of swine, was found in 28 percent of the lakes, even those not associated with any areas of swine or livestock.

Cocaine was found in a third of the lakes, most likely from atmospheric deposits, they said. The government estimates that 157 tons of cocaine are used annually in the United States — apparently enough for some of it to find its way into the air in the form of small particles. Eventually, it falls to the ground and into the water, they said.

Some of the chemicals analyzed have caused damage to aquatic ecosystems, according to previous research. Some of the pharmaceuticals belong to a class of chemicals called endocrine disrupters, which alter the expression of sex hormones in fish and other species.

Fish and mussels exposed to antidepressants and hormones at low concentrations have shown dramatic changes in behavior, reproduction and population. But the wider impact on ecosystems is not known, the researchers said.

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