Lake Nokomis in Minneapolis, shown here in October 2012, is popular with swimmers, fishermen and boaters, but it — like most Minnesota lakes — contains a cocktail of troubling chemicals at trace amounts. Kate Golden/Wisconsin Center for Investigative Journalism
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endocrine disruptors in the environment.

Water Watch Wisconsin

This story is part of Water Watch Wisconsin, a joint project of the Wisconsin Center for Investigative Journalism, Wisconsin Public Radio and Wisconsin Public Television. In it, we are examining the quality and supply of Wisconsin’s water. We welcome story ideas; please contact us at


On a midsummer morning last year at popular Lake Nokomis in Minneapolis, Mark Ferrey dipped a brown glass bottle into the water. His hands were gloved, he had drunk no caffeine, he wore no insect repellent. The slightest contamination would ruin the sample.

Below the sparkling surface swam muskies and walleye. Triathletes would be swimming there the next day. But Ferrey, a Minnesota Pollution Control Agency researcher, knew his sample would most likely turn up a cocktail of chemicals at trace levels.

According to results released last week, the Nokomis water was contaminated that day with a component of plastic, ibuprofen, a disinfectant used in hand soap, an antibiotic used on swine, a breakdown product of cocaine, an antidepressant, a fungicide and a drug used to treat Parkinson’s disease.

Some of the Nokomis cocktail’s most worrisome ingredients, the plastic component bisphenol A (BPA) and the disinfectant triclosan, are likely endocrine disruptors, chemicals that can interfere with the body’s hormone system.

Potent at extremely low concentrations, they can cause male fish to develop female characteristics. Because the endocrine system regulates a wide variety of the body’s functions, scientists have pegged them as possible causes for a host of health problems in wildlife and people.

When Ferrey started looking for endocrine disruptors in a dozen Minnesota lakes in 2007, he found them in every one — even the remote ones that were supposed to be pristine reference lakes.

That meant they “may not be as pristine as we were thinking,” Ferrey said.

In that first study, Ferrey’s collaborators lowered cages of male lab minnows into the lakes. After three weeks, most of them became feminized.

They produced an egg yolk protein that normally only females make. Some of them grew egg cells in their testes, or made fewer sperm. It was not just the lab fish — the resident sunfish, perch, minnows and shiners showed the effects of exposure to something like the hormone estrogen, too.

That prompted more research.

Ferrey, working with the U.S. Geological Survey and university scientists, sampled streams and rivers and found estrogenic chemicals downstream of wastewater treatment plants — and upstream, too.

In summer 2012, his agency sampled 50 more lakes, including Nokomis, with U.S. Environmental Protection Agency funding. A colleague is testing groundwater.

Nokomis was hardly unique. Ferrey found some chemicals in all but three lakes, and found 38 of the 125 largely unregulated chemicals he looked for. In a separate study of streams and rivers, Ferrey found 18 personal care products or pharmaceuticals.

Environmental experts said Minnesota’s results put pressure on Wisconsin to find out what’s in the water here.

Susan Sylvester, head of the Wisconsin Department of Natural Resources’ surface water bureau, told the Wisconsin Center for Investigative Journalism she was “impressed” by what the Minnesota researchers were able to show — but didn’t have the money for such monitoring.

“I think that we could probably assume that if we looked for these chemicals, we would find similar kinds of products as well,” Sylvester said.

Water samples from the popular Lake Nokomis in Minneapolis, shown here in October 2012, contained a component of plastic, an antibacterial soap ingredient, an antibiotic used on swine, a breakdown product of cocaine, an antidepressant, a fungicide and a drug used to treat Parkinson’s disease, according to one of two Minnesota Pollution Control Agency reports released Monday. Wisconsin’s lakes have not undergone similar scrutiny. Kate Golden/Wisconsin Center for Investigative Journalism

Many possible sources

By 2011, Ferrey’s team had reported finding ethinylestradiol, a synthetic contraceptive hormone commonly taken by women, in the water downstream of Minnesota wastewater treatment plants about 40 percent of the time.

Wastes from these plants are full of these chemicals. Treatment systems were not designed to remove endocrine disruptors and other pollutants, like pharmaceuticals and personal care products, that are often referred to in the scientific literature as “contaminants of emerging concern.”

The Minnesota researchers also found chemicals upstream, which means treatment plants were not the only source.

Ferrey’s latest study is unusual because he selected the 50 lakes randomly, instead of choosing those most susceptible to contamination. Many had no direct influence from wastewater treatment plants, or even public access.

Other possible sources are agriculture, industry, urban stormwater runoff and near-shore development. Even airborne particulate matter is suspect; Ferrey believes that may be why trace amounts of cocaine contaminated a third of the lakes he examined.

But for many of the chemicals, the sources were unclear. Minnesota has plenty of pigs — but how carbadox, an antibiotic approved only for use on swine, got into 28 percent of the lakes was ultimately “perplexing,” Ferrey wrote. Many were nowhere near livestock facilities.

Hormones and other chemicals

The researchers found other hormones, too — progesterone, testosterone, and others. Most are produced naturally, by wildlife and people. One lake contained the synthetic hormone mestranol.

Common chemicals included nonylphenol, a breakdown product from detergents, agricultural and indoor pesticides, and cosmetics in 10 percent of the lakes. It acts like estrogen on lab animals, is “extremely toxic to aquatic organisms,” and has been found everywhere from groundwater to breast milk, according to the EPA.

They found triclosan, an antibacterial chemical found in hand soaps, toothpastes and toys, in 14 percent of the lakes. It has disrupted estrogen metabolism and thyroid function in rats, can break down into dioxins in surface water, is in three-quarters of U.S. urine samples, and was deemed toxic to the environment by Canada last year.

BPA, found in 43 percent of the lakes, is “a reproductive, developmental and systemic toxicant in animal studies,” according to the EPA. It is being studied as a possible cause of early puberty in children.

BPA, hormones and nonylphenol were found “at concentrations that have been shown to impair endocrine function in fish and wildlife,” the researchers wrote.

Risks are unclear

Just because there are chemicals in the water does not mean they are hurting people or wildlife, including fish populations.

“It’s one thing to say it has an effect on an organism, quite another to say it’s having an effect on the entire ecosystem,” Ferrey said.

Endocrine disruption may not always mean doom. In one Minnesota study, St. Cloud State University researcher Heiko Schoenfuss found that although Mississippi River walleye showed evidence of endocrine disruption, the population seemed healthy.

Yet signs are emerging that populations may be affected: Schoenfuss found that minnows exposed to chemicals were slower to swim away from predators.

Scientists often cite a landmark seven-year study conducted by Canadian researcher Karen Kidd, in which she intentionally tainted a research lake in Ontario with the synthetic hormone used in birth-control pills.

Among the resident fathead minnows, the males were feminized. The females kept producing  egg-yolk proteins beyond their breeding season.

The minnow population collapsed to near extinction.

Then some of the bigger fish, like lake trout, began to die off.

The fish rebounded only when Kidd stopped dosing the lake.

Potent in tiny amounts

Kidd gave the lake estrogen in “environmentally relevant” concentrations, the same low levels that have been found in lakes and streams.

Five parts per trillion. That’s like five drops in 20 Olympic swimming pools.

The fathead minnow is a dull, common bait fish, but it has become an important species for research on endocrine disruptors. Here, fish are being raised for research at a U.S. Environmental Protection Agency laboratory in Duluth, Minn. Kate Golden/Wisconsin Center for Investigative Journalism

Only recently have scientists been able to detect these chemicals at such tiny concentrations.

The chemistry is so exacting that Ferrey had to pack his lake samples in ice and FedEx them to a specialized laboratory in Vancouver, Canada — at a few thousand dollars per sample — to find out what was in them.

Warren Porter, a professor of zoology at the University of Wisconsin-Madison, said the data raised serious issues.

Many of the chemicals are soluble in fat and not easily broken down, which could allow them to accumulate in the food chain, as DDT and PCBs do.

Their presence in surface water suggests that they may also reach the groundwater, an environment where they are less likely to degrade, Porter said.

The presence of chemicals that act like hormones or suppress the immune system, Porter said, could affect “normal neurological function, immune function, hormonal function and developmental processes which are sensitive to chemicals in the parts per trillion — which is what is being detected here.”

Effects controversial

Some prominent experts have criticized the slew of science that is being done on these chemicals in such small concentrations.

Drinking water managers caution that merely detecting chemicals in water does not mean they are harming anyone. Health effects research has not kept pace with improvements in detection technology, noted the American Water Works Association in 2008 comments to the U.S. Environmental Protection Agency.

“National drinking water regulations should not be driven by the ‘contaminant du jour,’” wrote the nonprofit organization, which represents 4,700 utilities nationwide.

The chemical industry’s American Chemistry Council has funded research saying the case for widespread low-dose effects has been exaggerated and contrary evidence has been ignored.

Ferrey and other experts said parts per trillion is a relevant concentration in both fish and people, as the Canadian study showed. Ferrey uses the example of botulism toxins, which can kill people at even lower concentrations.

“It puts it in some perspective,” Ferrey said, “that we’re not talking crazy talk. We’re talking about concentrations that can be very powerful.”

Many scientists say that while trace amounts of a single chemical may not harm people or wildlife, most people are constantly exposed to a wide variety of chemicals whose cumulative impacts are not fully known but may pose risks.

A woman’s lifetime exposure to estrogens, for example, has been shown to increase her risk of breast cancer, said Angela Bauer, a professor of human biology at the University of Wisconsin-Green Bay.

Bauer and her collaborators found estrogenic chemicals in private well samples from northeastern Wisconsin in 2009.

The effective amounts were lower than those causing endocrine disruption in wildlife. But they were high enough to be worrisome, Bauer said, because they are likely not the only source of endocrine disruptors to which residents are being exposed over time.

“I think about this almost every day,” Bauer said.

Coming Wednesday: Twenty years after fatal outbreak, Milwaukee leads on water testing

The nonprofit Wisconsin Center for Investigative Journalism ( collaborates with Wisconsin Public Radio, Wisconsin Public Television, other news media and the UW-Madison School of Journalism and Mass Communication. All works created, published, posted or disseminated by the Center do not necessarily reflect the views or opinions of UW-Madison or any of its affiliates.

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Kate GoldenMultimedia director and reporter

Kate Golden, multimedia director and reporter, specializes in environmental stories and data visualizations.

3 replies on “The hunt for endocrine disruptors”

  1. Excellent article and series. Thank you!

    It makes sense that wastewater discharges can’t explain all the contamination being found, especially in “pristine” areas.

    In Wisconsin (and many other states), roughly 95% of all the public wastewater treatment plant sludge is LAND-SPREAD on agricultural fields statewide, after very little treatment.

    This means that literally MILLIONS of pounds of mixed industrial and household chemicals, pesticides and prescription medications are broadcast far and wide on soil surfaces every year. Some are plowed under, but then re-exposed later with future plowing, earthworm tilling, plant uptake, and plant decomposition.

    Rain and snowmelt are undoubtedly carrying these chemicals into nearby streams, rivers and lakes, especially when land-spreading is more carelessly done. Groundwater is also being contaminated.

    Also, large quantities of some of these chemicals will undoubtedly volatilize into the air (like perfume from a bottle) from millions of acres of land-spread farm fields, especially during warm weather. These airborne chemicals drift downwind and settle-out with rain and dust on “clean” lands and waters.

    We might be able to cut back on uses of some of the pesticides and antibiotics, or restrict some industrial chemicals, but we can’t stop people from taking medications.

    This means we’re going to have to improve wastewater treatment and sludge disposal … drastically.

    Unfortunately, our political processes are also “polluted” by money and power inequalities. It will be extremely expensive to clean-up all the public and private wastewater treatment systems to stop these types of environmental releases … so political resistance will be intense.

  2. I served for 4 years on a Wisconsin DNR “Citizen Advisory Committee” (ending about 10 years ago?), which the Natural Resources Board had charged with finding a maximum “safe” level of toxic chemicals called “PCBs” (polychlorinated biphenyls) in waste sludges being spread on Wisconsin cropland.

    Our goal was to create a new “PCB Soil Criteria” that the DNR could use for regulating land-spreading.

    The DNR also created a “Technical Committee” of toxicology experts and chemists to investigate the issue and advise our committee. They sampled 50 sewage plants (large and small) and found PCBs in ALL the sludges.

    (Analysis was difficult, because samples were contaminated with a confounding variety of chemicals similar to PCBs. When I insisted on knowing what those “similar” chemicals were, we were told the most dominant one was PBDE, a worrisome flame retardant heavily used in our society.)

    Our DNR “citizen” committee consisted of roughly 25 “stakeholder” appointees … primarily lawyers, lobbyists and tech consultants representing municipal sewage treatment plants, paper industries, foundaries, and municipal harbors, because they all generated huge quantities of contaminated waste sludges every year.

    Some were already land-spreading and others wanted to start.

    Thousands of man-made chemicals (including PCBs, dioxins, pesticides and endocrine disruptors), as well as elements (lead, arsenic, mercury) are measurable in many of these waste sludges.

    Many are known toxins, but no one knows the health impacts of low-level, chronic, cumulative, life-long exposure to traces of thousands of these chemicals ALL AT ONCE from land-spreading sludges, especially combined with all our other exposure routes.

    But it’s absolutely certain that crops, livestock and FOODS are being contaminated nationwide from sludge land-spreading. And sludge is definitely contaminating our groundwater, rivers, lakes and wildlife nationwide, to varying degrees.

    Significant health risks seem likely, but this is a poorly researched, BADLY regulated issue.

    It’s a huge, uncontrolled experiment.

    After 4 years of struggle on our DNR committee, the lawyers and lobbyists blocked adoption of any PCB Soil Criteria in Wisconsin, because we found that even a minimal health-based PCB limit would have outlawed most land-spreading (… even before adding any risks from the thousands of OTHER contaminants in these sludges.)

    Safe disposal was deemed “too expensive” and politically unacceptable. Instead, DNR was forced to do “risk management” (ie: mostly business-as-usual.)

    The few public interest reps on the committee (like me) were out-numbered, out-maneuvered, ridiculed, and isolated … achieving only improved sampling, better record-keeping of treated fields, and wider distribution (to dilute this deliberate soil pollution).

    It was an awful experience.

    Since then, the DNR has only limited the “loading” on each field, to keep each one from getting “too contaminated,” though the DNR’s own expert committee had already made it clear that even ONE sludge application could be unsafe.

    This is how health protection decisions are commonly made in Wisconsin (and elsewhere). It’s not reassuring.

  3. Many disturbing political decisions were made during our committee’s deliberations (see below).

    One example: Mid-way through our committee process, the majority of political appointees on the committee decided (over my objections) to set a “PCB Soil Criteria” that would protect 95% of the human population exposed to PCBs due to land-spreading of PCB contaminated waste sludges ( — exposed directly and/or through consumption of crops, vegetables, meat, dairy and other foods produced on polluted land over 70 years.)

    In other words, the health of 5% of the exposed human population would NOT be protected — 1 person out of every 20 people. The lives and happiness of 286,300 residents of Wisconsin were considered expendable (— 5% of Wisconsin’s 5,726,000 people in 2012.)

    Yet, even after the committee decided to sacrifice 286,300 people in Wisconsin, the scientists’ assessed health risks due to PCB exposures were still so high that the final proposed “PCB Soil Criteria” would still have outlawed most land-spreading. (Even a heavily compromised PCB limit would have been in extremely low “parts per billion”(ppb), because PCBs are so pervasively toxic and accumulate so easily in our bodies.)

    So the sludge lobbyists blocked even the weakened criteria — and left ALL of us at higher risk.

    It’s vitally important to remember that PCBs are only ONE of the many toxic chemicals being land-spread with many waste sludges, so the lobbyists also blocked limits on the ADDED toxic risks of thousands of these OTHER chemicals, just by association.

    Anyone who trusts the government to protect them from serious health risks is dead wrong.

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