A commonly used water treatment system appears to be highly effective in decreasing neonicotinoid concentrations in finished drinking water, according to a new report.
In the news this week was a report that finished tap water grab samples collected from the University of Iowa's water treatment system in 2016 contained three kinds of neonicotinoids in concentrations ranging from 0.24 to 57.3 nanograms per liter (1 nanogram = 1/1,000,000,000 gram, or 1-one trillionth of a gram).
Samples collected from the University of Iowa sand filter treatment system indicate no apparent removal of two of the three seed treatment compounds, but modest removal (∼50%) of one. In contrast, the concentrations of all neonicotinoids were substantially lower in the city treatment facility's finished water using granular activated carbon (GAC) filtration. The removal of one of these neonics (thiamethoxam) in the university's treatment system, it turns out, was due to chemical breakdown under high-pH conditions during lime softening. On the other hand, GAC filtration in the city's water treatment system rapidly and nearly completely removed all three neonicotinoids (clothianidin, imidacloprid and thiamethoxam), the report said.
Gregory LeFevre, a study author and University of Iowa environmental engineer, said in a Washington Post article that the finding was important "but not immediate cause for alarm.” These results seem to be more informative about the differences in water treatment systems. This information should be instructive to EPA when it reviews the human health risks of these products this year and in 2018 (already scheduled by EPA). GAC is identified in the report as a potentially effective management tool for decreasing neonicotinoid concentrations in finished drinking water, and suggests sand filters may be inadequate.
Crop protection compounds, including neonicotinoids, are important for supplying consumers with safe, abundant, and nutritious, high quality and reasonably-priced foods. Pesticide use is extensively regulated by federal and state laws. Applicators and handlers are certified by the Iowa Department of Agriculture & Land Stewardship, with training provided by Iowa State University specialists. Iowa farmers are committed to these training programs and continuing the safe use of these products to protect their health and safety, and those of their families, our communities and the environment. EPA establishes the product label that sets use requirements that farmers must follow for safe use.
Applying neonicotinoids as a seed treatment is one of the most precise and environmentally responsible methods of crop protection, allowing growers to significantly minimize any potential worker and environmental exposure. A review of published science by EPA indicates that these products are not persistent in the environment when applied according to the label, and the potential risk from dietary exposure from food, feed and drinking water, if it happens, does not harm people.
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