Studies show unregulated chemicals widespread in lakes, rivers
Two studies released this week by the Minnesota Pollution Control Agency (MPCA) confirm that a wide variety of unregulated chemicals are ending up in Minnesota's lakes and rivers. The chemicals, including pharmaceuticals and personal care products, are of concern because many have properties that can interfere with the functioning of hormones in animals and people.
Previous studies have shown the chemicals are often found in streams that receive wastewater discharges. Limited sampling has also revealed that they are often found in lakes, which do not typically receive wastewater. But the number of lakes and rivers included in those investigations was not large enough to give an accurate picture of the extent of the contamination. The two latest studies provide statistical evidence of just how widespread the chemicals are in Minnesota's surface waters.
"What these studies really are measuring is the footprint of our society and how we live," said MPCA Commissioner John Linc Stine. "Our lakes and rivers are reflecting the chemicals we use and put into our bodies. These chemicals have very beneficial uses, but unfortunately they tend to stick around in the environment after their first use."
In the two studies, the MPCA in 2010 and 2012 sampled lakes and rivers using funds from the state of Minnesota and the US Environmental Protection Agency, part of nationwide EPA surveys to find out what's in the nation's waters.
For the lakes study, 50 lakes were randomly selected across Minnesota. Samples were collected and analyzed for 125 chemicals. The study included analysis of "endocrine-active compounds" (EACs), so called because they mimic or interfere with the actions of naturally occurring hormones. These chemicals can have adverse effects on aquatic ecosystems and fish.
Results of the lake study were generally consistent with findings of previous but smaller studies that found commonly used chemicals widely distributed in Minnesota lakes. The insect repellent DEET was found in 76% of the lakes sampled, making it the most frequently detected chemical. Chemicals not previously analyzed - including cocaine, the antidepressant amitriptyline, and the veterinary antibiotic carbadox - also were often detected in the lakes.
MPCA officials said the detection of cocaine was unexpected, one for which they couldn't account except that other studies have shown it can attach to fine particles and might be transported long distances through the atmosphere.
The rivers study analyzed 18 chemicals, including several pharmaceuticals and personal care products, and was conducted at 150 river locations selected at random. Parabens, a family of chemicals used as preservatives for food and cosmetics, were commonly found, with methylparaben detected in over 30% of the samples. A breakdown product of the corrosion inhibitor benzotriazole was found in 12 percent of the samples. Carbamazepine, used in medications to treat attention deficit hyperactivity disorder, and several antidepressants were also found.
Many of the chemicals in the MPCA studies were detected at very small concentrations, in the low parts per trillion. Such levels are of concern because EACs have the potential to adversely affect fish and other aquatic organisms even at extremely low levels.
One part per trillion is roughly equivalent to 1 drop in a pool of water covering the area of a football field 43 feet deep.
The MPCA plans to continue testing surface waters for pharmaceuticals and EACs on a rotating five-year basis to identify any trends that may be occurring.
Reports on the studies and summary information are available on MPCA's webpage at http://www.pca.state.mn.us/iryp8f4. The two reports are titled "Pharmaceuticals and Endocrine Active Chemicals in Minnesota Lakes" and "Pharmaceuticals and Personal Care Products in Minnesota's Rivers and Streams".