Traces of neonicotinoids, the best-selling class of controversial pesticides linked to declining bee populations, have been detected in the U.S. water supply, according to a team of scientists from the U.S. Geological Survey and the University of Iowa.
Imidacloprid, a type of neonicotinoid, was detected in more than half of water samples from streams tested in 2015, and the latest research points to traces of three types of neonicotinoids in drinking water for the first time. The research is published in the journal Environmental Science & Technology Letters.
The researchers tested samples from water taps in Iowa City in 2016, finding neonic concentrations ranging from 0.24 to 57.3 nanograms per liter, according to the Post, which is parts per trillion, “roughly equal to a single drop of water plopped into 20 Olympic-size swimming pools.” Every sample the researchers tested during a seven-week period after crops were sprayed with the pesticides contained three types of neonicotinoids: clothianidin, imidacloprid, and thiamethoxam.
While the EPA has yet to determine safe levels of neonics, the class of pesticides is so controversial, primarily for its link to honeybee population declines, that the European Union has enforced strict restrictions on its use in efforts to help bees and other threatened pollinator populations rebound.
Still, producers of neonics, like Bayer, insist the chemicals are safe, designed, the company says, to be more environmentally friendly than competing pesticides. A 2015 study conducted by George Washington University and the National Institute of Health found little human health risk from acute exposure. But the longterm effects of cumulative exposure is not yet known.
“Having these types of compounds present in water does have the potential to be concerning,” Gregory LeFevre, a study author and University of Iowa environmental engineer, told The Washington Post, “but we don’t really know, at this point, what these levels might be.”
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