Neonicotinoids found in University of Iowa drinking water


activate charcoal
Activated carbon filters were shown to effectively remove neonic insecticides from drinking water. (Minnesota Department of Health)
Jenna Ladd | April 7, 2017

Neonicotinoids, a specific class of pesticides, have been detected for the first time ever in tap water according to a recently published study by University of Iowa scientists and the U.S. Geological Survey.

Neonics became widely used by farmers in the early 1990s, mostly because they are harmful to insects but to not other species. The pesticides are still very popular, despite mounting research that suggests they are lethal to bees and other helpful insect species.

A team of researchers compared tap water samples from the University of Iowa drinking water supply to samples of Iowa City municipal tap water. Tap water from each source was tested for three primary neonicotinoid types: clothianidin, imidacloprid and thiamethoxam. The University of Iowa filtration system removed only a minute amount of each insecticide. In contrast, the City of Iowa City successfully removed 100 percent, 94 percent and 85 percent, respectively, of each primary neonicotinoid.

Researchers say this can be explained by the different filtration systems used in each facility. Neonicotinoids readily dissolve in water, they say, and therefore easily slip through the University’s sand filters. The city employs an activated carbon filter that successfully removes the chemicals. Dr. Gregory LeFevre, University of Iowa environmental engineer and one of the study’s authors, said that activated carbon filters can be a cost-effective way to tackle these insecticides in an interview with the Washington Post. In fact, the University purchased a small activated carbon filtration system shortly after the study wrapped up in July 2016.

Levels of neonicotinoids in University water were relatively small, ranging from 0.24 to 57.3 nanograms per liter. LeFevre said, “Parts per trillion is a really, really small concentration.” The U.S. Environmental Protection Agency has not set a limit for neonicotinoid levels in drinking water. The study’s authors argue that more research is called for to assess neonicotinoid exposure on a larger scale. LeFevre explained, “Without really good toxicity data it is hard to ascertain the scale of this, but whenever we have pesticides in the drinking water that is something that raises a flag no matter what type of concentration it is.”

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