Estrogen, Gabapentin and DEET in Park Waters: What Four Midwest National Parks Found, 2013–2015

"All drains lead to the lake," the saying goes — and that includes what goes down sinks, toilets and washing machines. Many ordinary things people do every day leave traces in lakes and streams that no one can see. Some of those traces are contaminants of emerging concern, and from 2013 to 2015 the National Park Service went looking for them.

Collecting a stream sample at Indiana Dunes National Lakeshore. NPS photo.

The study

In 2013 the NPS Great Lakes Inventory and Monitoring Network joined six other networks and the U.S. Environmental Protection Agency in analyzing park surface waters for wastewater indicators, pharmaceuticals, personal care products and pesticides. The Great Lakes Network sampled four parks: Mississippi National River and Recreation Area, Indiana Dunes National Lakeshore, Apostle Islands National Lakeshore and Isle Royale National Park (where wastewater indicators were not analyzed).

City parks carried more

More chemicals, at higher concentrations, turned up at the two urban parks — the Mississippi River and Indiana Dunes — than at remote Apostle Islands and Isle Royale.

Fourteen wastewater indicators were found across the three parks tested for them, among them:

• Bisphenol A, used mainly to make polycarbonate plastic and epoxy resins, and organophosphate flame retardants, common at all three parks — Bisphenol A up to 350 ng/L at Indiana Dunes;
• caffeine, up to 215 ng/L at Indiana Dunes;
• fragrances such as galaxolide, camphor and acetophenone, and the antimicrobial triclosan;
• two forms of estrogen, equilenin and estrone, found in the same sample at more than 100 ng/L. Concentrations above 5 ng/L are known to affect reproduction in at least one species of minnow.

Pharmaceuticals were most often pain relievers, anticonvulsants, antidepressants and diuretics. The insect repellent DEET was in 92% of samples at both Isle Royale and Indiana Dunes.

The herbicide levels — simazine above 1,000 ng/L in two Indiana Dunes samples, and metolachlor on the Mississippi — were similar to those reported for other major U.S. urban rivers. None exceeded the EPA's drinking-water limits for herbicides.

Is it harmful?

With a few exceptions, concentrations were far below the screening values or benchmarks at which human health can be affected. The exceptions: metformin, atrazine and simazine each came close to a human-health benchmark in at least one sample, and the diuretic hydrochlorothiazide exceeded a health-based screening value in seven samples.

What comes next

The results give Midwest national parks a baseline for these chemicals, and show how much is still unknown about where they come from, how they reach park waters and what they do to aquatic life. Sampling continued at inland lakes in Pictured Rocks and Sleeping Bear Dunes national lakeshores in 2016, with Voyageurs National Park and Grand Portage National Monument planned for 2017.

Sources

Based on "Emerging Concern Among 'Every Day Chemicals,'" National Park Service, Great Lakes Inventory and Monitoring Network, summarizing Elliott and VanderMeulen (2016), "A regional assessment of chemicals of concern in surface waters of four Midwestern United States national parks," Science of the Total Environment; a work of the United States government in the public domain.