ORIGINAL ABSTRACT

Glyphosate, the most widely used herbicide in the United States, is applied to control broadleaf weeds and grasses. Public concern is mounting over how pesticides affect human and environmental health. Glyphosate toxicity in animals is known, but human carcinogenicity is controversial, and limited epidemiologic evidence suggests associations between exposure and respiratory diseases (e.g., asthma) and adverse child neurodevelopment. Understanding the extent of the general U.S. population exposure to glyphosate is important. To examine temporal trends in exposure to glyphosate, we determined urinary concentrations of glyphosate among U.S. children and adults from three cycles of the National Health and Nutrition Examination Survey (NHANES) conducted 2013-2018. Most of the population (70.0%-81.7%, depending on cycle) was exposed, including children as young as 3 years of age. Concentrations decreased from 2013 to 2018 by 38%; the decline was smaller in younger age groups. The downward trend likely reflects changes in glyphosate use resulting, at least in part, from changes in agricultural practices, regulatory actions, and shifts in public awareness regarding glyphosate toxicity. Continuing glyphosate biomonitoring will help understand how changes in use and actions to restrict applications of this common pesticide affect human exposures.