An endocrine disruptor interferes with the hormonal systems of living things. The endocrine system is composed of hormones, which send chemical signals throughout the body to regulate the body systems, and are responsible for maintaining bodily growth, development, sexual functions, brain function, and appetite. Endocrine disruptors interfere with these activities by blocking the effects of hormones or speeding up their breakdown. The effects of endocrine disruptors were documented in a study in Lake Apopka, Florida. Alligators in the lake were suffering from reproductive issues due to low sex hormone levels and gonadal abnormalities. This was linked to the heavy presence of fertilizer runoff in the lake; fertilizers can act as endocrine disruptors.
Presently, these endocrine disruptors and other potentially toxic chemicals have been detected in Minnesota lakes and rivers. The lake study sampled 50 randomly selected lakes across Minnesota in 2012 with EPA funding; 47 of the lakes contained at least one potentially harmful chemical. The waters were tested for the presence of 125 chemicals, many of which are known endocrine disruptors. The testing showed that the insect repellent DEET was present in 76 percent of the lakes sampled. As a result, it was the most frequently found chemical. Other compounds discovered included cocaine, the antidepressant amitriptyline, and a veterinary antibiotic called carbadox.
The rivers analysis was conducted in 2010 and was a test for 18 chemicals. The study was conducted at 150 randomly-selected river locations across Minnesota. The chemicals being examined were pharmaceuticals and personal care products. Commonly discovered chemicals included parabens, which are preservatives for food and cosmetics and are weakly estrogenic. Several antidepressants were detected, along with carbamazepine, which is used to treat attention deficit hyperactivity disorder.
Many of the chemicals detected were in the low parts per trillion; however, endocrine disruptors can produce adverse effects in living things at very low levels. These chemicals could come from people flushing their medications down toilets and drains. The Minnesota Pollution Control Agency suggests throwing these drugs into the trash or at specially-designated drop-off sites for disposal so that they do not enter the water supply. The chemicals could also be attached to dust particles which fall into water systems.
Minnesota is not the only state with potentially contaminated water. A 2002 study conducted by the U.S. Geological Survey found that 80 percent of all United States streams contained traces of water contaminants such as detergents, drugs, antibiotics, steroids, disinfectants, perfumes, and pesticides.
Photo of Clearwater Lake in Minnesota courtesy of Chad Fennell via Wikimedia Commons.
Environment: The Science Behind the Stories by Jay Withgott and Scott Brennan Third Edition. (2008). Pearson Benjamin Cummings.