A chemical associated only with X-ray technology is showing up in Lake Kabetogama in Voyageurs National Park and other northern lakes, one of many industrial compounds showing up in samples taken from Minnesota waterways.

The Minnesota Pollution Control Agency on Tuesday released the results of its latest survey of 11 lakes and four rivers tested for 125 different chemicals, many of which are suspected of being harmful to the environment and, possibly, to humans.

Several of the compounds are considered so-called endocrine-disrupting chemicals that, in other studies, were shown to cause male fish to develop female characteristics and spurred other disruptions in ecosystems.

The survey shows that even remote Minnesota waters are contaminated by a variety of pharmaceuticals, ingredients of personal care and hygiene products as well as endocrine-disrupting compounds — everything from antibiotics, nicotine, caffeine and antidepressants to medications that regulate diabetes, cholesterol and blood pressure.

The chemical DEET, for example, a common ingredient in most commercial mosquito repellents, was found in 10 of the 11 lakes studied.

The X-ray contrast drug iopamidol, which is injected into some patients who are X-rayed, showed up in 73 percent of the lakes tested. But, inexplicably, remote Lake Kabetogama contained the highest level, even though there is no obvious source on or near the lake or even upstream.

Other northern lakes also tested positive for chemicals:

— Northern Light Lake, north of Grand Marais and just outside the Boundary Waters Canoe Area Wilderness, contained DEET, BPA, diltiazem, the antibiotics ciprofloxacin, erythromycin, trimethoprim, and clinafloxacin, which is a human antibiotic.

— In Stewart Lake, north of Two Harbors, researchers also found iopamidol as well as clinafloxacin and other chemicals.

— Elk Lake, in Itasca State Park, contained DEET, cotinine, metformin, colchicine and BPA.

Most of the compounds found were in small amounts — just parts per trillion. That’s below the expected human problem level for some but may be enough to be making trouble for aquatic creatures.The PCA is working with the Minnesota Department of Health to evaluate potential human health impacts from long-term, low-level exposure to the chemicals found in the state waterways.

“It’s not just so much that we are finding these things. We have been for years. We now want to go beyond detection and determine what effect they having on fish and wildlife. And what concerns should we have about human health,” Mark Ferrey, the study’s lead author, said in an interview.

The latest survey echo results from 2008 and 2009 testing, with the chemicals showing up even in northern lakes considered remote and pristine, far from municipal or industrial pollution sources.

Ferrey said scientists have found these chemicals for years below city wastewater plants. But recent research has shown many in remote areas.

“Ferrey said that, in addition to municipal wastewater treatment plants, residential septic systems from cabins and lake homes as well as stormwater runoff are among the potential sources of contamination to surface water.

It could just be a few people impacting each specific waterway, Ferrey noted.

“Even Kabetogama, while it’s fairly clean lake, has a certain amount of development around it. What we’re finding there may be a fingerprint of what is in the people who live around the lake. What we find is a fingerprint of what (compounds) our society is using,” Ferrey said. “But this stuff (iopamidol) appears in urban lakes, outstate developed lakes and even relatively undeveloped lakes … so it could be from local sources or it could be floating around in the air. We don’t know yet.”

The PCA asks that consumers not toss any pharmaceuticals or other chemicals down their drain, noting wastewater plants aren’t designed to remove them. Instead, take the drugs to a recycling center, located at many law enforcement offices.