ROCHESTER, Minn. (Fox 47) -- Many people don't think too much about using synthetic products to enhance their everyday lives.
But what many don't know, is what they're putting down the drain can end up in lakes, rivers and streams.
"There's a very close connection, it appears, between what we do and what appears in our lakes and rivers and streams," said Mark Ferrey from the Minnesota Pollution Control Agency.
And that could be dangerous to animals, and people."
"We know that it can, in certain circumstances, affect fish population," Ferrey said.
The Minnesota Pollution Control Agency tested 50 random lakes in the state for 125 chemicals.
"It gives us a statistical certainty about what our water's like across the state in a way that we've never had before," Ferrey said.
Deet, a common insect repellent, was found in 76 percent of the lakes tested.
BPA, a plastic chemical, showed up in 40 percent of the sampled lakes.
And an anti-depressant - amitriptyline - was found in almost 30 percent of the samples.
And, one that may be surprising to people, cocaine was found in one-third of the lakes sampled.
"The fact that a lot of cocaine is used in this country every year - about two or three percent of the population uses cocaine - by current estimates, maybe it's not surprising, in the end, that we're seeing so much cocaine in our environment," Ferrey said.
Ferrey explained these chemicals contain endocrine-active compounds that mimic or interfere with naturally occurring hormones in fish.
"Reproductive behavior, growth behavior - all sorts of different kinds of behaviors - can be elicited when they encounter these kinds of chemicals, at just trace concentrations," Ferrey said.
The types of chemicals researchers discovered in the lakes are banned in some countries. Ferrey said he hopes more consumers will pay attention to what goes down the drain - including car wash detergents, prescription drugs, and synthetic materials that may be dangerous to the environment.
"Because, waste water treatment plants, even though they work very, very well, and they do everything we ask of them, don't take out everything that we're talking about in terms of these contaminants. Some of that gets through in our surface water at trace concentrations," he said.
Ferrey reminds Minnesotans that prescription drugs can be taken to drug drop-off centers and unregulated chemicals can be disposed of at chemical waste facilities.