Residential proximity to agricultural glyphosate use and neurobehavior in the CHAMACOS study

Abstract

BACKGROUND AND AIM: Glyphosate herbicides are the most widely used pesticides in the world. In California, agricultural use and total sales of glyphosate have more than doubled in the past 20 years. However, few studies have evaluated the human health effects of exposure. Our aim was to assess the relationship of agricultural glyphosate use within 1 km of residences with cognition and behavior in adolescence and young adulthood. METHODS: We collected residential history information during pregnancy and childhood in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) birth cohort. Using California Pesticide Use Report data, we estimated agricultural glyphosate use within 1 km of residences during the prenatal period and from 0-5 years of age, weighted for wind direction. We estimated associations with: Full-scale Intelligence Quotient, Verbal Comprehension, Working Memory, Processing Speed and Perceptual Reasoning from the Wechsler Intelligence Scale for children, 4th edition at 7 and 10.5y; internalizing (anxiety and depression) and externalizing behaviors (hyperactivity and attention) from the Behavior Assessment System for Children-2 at 16 and 18y; and police encounters, delinquent acts, and risk-taking behaviors at 18y. RESULTS:A two-fold increase in glyphosate use within 1 km of postnatal residences was associated with more youth-reported depression (β=1.3, 95% Credible Interval (CrI): 0.2, 2.5), and maternal-reported internalizing behaviors (β=1.3, 95% CrI: 0.2, 2.7), driven by associations with anxiety (β=1.2, 95% CrI: 0.2, 2.3) at 16 and 18y. Residential proximity to glyphosate use during pregnancy or early childhood was not associated with other behavioral or cognitive domains. CONCLUSIONS:Though we observed associations of early childhood residential proximity to agricultural glyphosate use with a slight increase in internalizing behaviors, overall associations were null for most cognitive and behavioral outcomes. Future studies of neurodevelopment and glyphosate biomarkers would integrate exposure from diet, agricultural and home use. KEYWORDS: glyphosate, agriculture, cognition, behavior, children, adolescents