(NaturalNews) The Minnesota Department of Health is conducting an investigation into the popular insect repellant N,N-Diethyl-meta-toluamide (DEET), in response to concerns over its prevalence in groundwater, rivers and lakes that serve as drinking water sources.
DEET has also been detected downstream of wastewater treatment plants.
"We shower, it goes down the drain, and it ends up in wastewater that goes into rivers," state toxicologist Helen Goeden said.
DEET, the active ingredient in most chemical insect repellants, may be toxic to the nervous system.
"[DEET] is probably the most effective insect repellent known, but it is also potentially quite toxic and it can destroy substances such as plastics and synthetic fabrics, so it must be used with care and only in accordance with package directions," writes Phyllis A. Balch in her book Prescription for Nutritional Healing, 4th Edition.
"Never apply a product that has more than 35 percent DEET to the skin," she writes. "Children are especially at risk for problems due to this potentially hazardous chemical, so their skin exposure to it should be strictly limited. To be safe, apply DEET to clothing and use it sparingly, if at all, on the skin."
Little is known about DEET's effects if ingested in drinking water, however. Yet a 2004 U.S. Geological Survey study found that it was in the top 10 most commonly detected chemicals in a survey of 65 Minnesota lakes and streams. A 2006 study confirmed the chemical's presence in one-third of 43 Mississippi River sites tested in the state, while a 2009 study found it in every one of 12 lakes and four rivers tested.
"It showed up just about everywhere," said Mark Ferrey, a researcher at the Minnesota Pollution Control Agency.
As a consequence, the state Department of Health has designated DEET as one of seven "chemicals of emerging concern" whose safety it will assess during the coming year.
The U.S. Environmental Protection Agency estimates that one in three U.S. residents uses a DEET product each year.