Summary of the Public Health Goal for Glyphosate
A Public Health Goal (PHG) of 1,000 ppb is developed for glyphosate in drinking water. California’s and U.S. Environmental Protection Agency’s (U.S. EPA’s) Maximum Contaminant Levels (MCLs) are 700 ppb based on systemic toxicity (renal tubular dilation) in a three-generation rat reproduction study with an NOAEL of 10 mg/kg-day. Glyphosate is a non-selective systemic herbicide used in agriculture, rights-of-way and aquatic systems. Exposure to glyphosate may occur from its normal use due to drift, residues in food crops and from runoff into potential drinking water sources. Following acute exposure, glyphosate has low systemic toxicity to mice and rats. In humans, irritation of the oral mucous membrane and gastrointestinal tract is the most frequently reported effect in suicide attempts with glyphosate-surfactant formulations. In most of the short-term and long-term toxicity studies, there were no treatment-related gross or cellular changes except reduced body weights and increased liver weights at relatively high doses. After a thorough review of the available studies, the U.S. EPA classified glyphosate as a Group E carcinogen (evidence of noncarcinogenicity for humans). Glyphosate is not mutagenic or teratogenic and there is no evidence for reproductive toxicity in multigeneration studies in rats. We consider the results from a rabbit teratology study with a no-observed-adverse-effect level (NOAEL) of 175 mg/kg-day for maternal toxicity (diarrhea and mortality) as the appropriate basis for toxicological evaluation in humans. Based on these data, OEHHA has developed a PHG of 1.0 mg/L (1,000 ppb) for glyphosate in drinking water, which is higher than the federal MCL of 700 ppb.
- Glyphosate