FROM THE EPA, JANUARY, 2017:
EPA has updated its Human Health Benchmarks for Pesticides in drinking water to reflect the latest scientific information. The benchmarks are levels of certain pesticides in drinking water or source waters for drinking water at or below which adverse health effects are not anticipated from one-day or lifetime exposures. First developed by EPA in 2012, the benchmarks are intended to be used for informational purposes by states, tribes, water systems and the public to help interpret monitoring data for pesticides for which there are no drinking water standards or health advisories. These revised benchmarks incorporate updated toxicity assessments from the pesticide registration process and exposure assumptions derived from the EPA’s Exposure Factors Handbook.
https://www.epa.gov/dwstandardsregulations/drinking-water-contaminant-human-health-effects-information#benchmarks