Neonicotinoids, a targeted (as opposed to broadly sprayed) insecticide common in agriculture, have been detected in drinking water. Since in modern times we can even detect parts per quadrillion in drinking water, is the health of Iowans at risk?
Concern over the use of neonicotinoid pesticides has grown as media have reported studies finding them in rivers and streams, and environmental groups have attempted to link them with declining bee populations and health effects in other animals, so far to little success. A group (disclosure: funded by an environmental group) from University of Iowa and the U.S. Geological Survey tested water as it went through two different water treatment systems.
They found that a system serving Iowa City, which uses granular activated carbon filtration, removed 100 percent, 94 percent and 85 percent of the neonicotinoids clothianidin, imidacloprid and thiamethoxam, respectively. The rapid sand filtration system serving the University of Iowa reduced the same substances only by about 1 percent, 8 percent and 44 percent, respectively. Drinking water samples from this treatment plant contained between 0.24 and 57.3 nanograms of individual neonicotinoids per liter.
Because thet are not considered harmful by EPA, regulatory limits for these substances are not currently in place. There is no evidence that neonicotinoids impact human or animal health, the researchers note. They add that more studies are needed to figure out if chronic, low-level exposure to neonicotinoids might be harmful.
Citation: Occurrence of Neonicotinoid Insecticides in Finished Drinking Water and Fate during Drinking Water Treatment, Environ. Sci. Technol. Lett. April 5, 2017, DOI: 10.1021/acs.estlett.7b00081