A pilot study of glyphosate, and preterm birth among blacks and whites

Abstract

BACKGROUND AND AIM: Glyphosate was first registered as an herbicide in the United States in 1974. It has since been linked to birth defects in animal models. Additionally, in vitro studies suggest that glyphosate has anti-androgenic and anti-estrogenic activities including the ability to interfere with aromatase activity. One observational human study found a statistically significant correlation between higher maternal glyphosate levels and shortened gestational length. However, no studies have investigated potential race-disparities in gestational glyphosate exposure or effects. METHODS: A nested case control pilot study enrolled 26 women with a preterm birth (37 weeks completed gestation) and 26 term births matched by race from a larger cohort study. Second trimester urine samples, collected at 18-22 weeks of gestation, were analyzed for specific-gravity corrected glyphosate using liquid chromatography-tandem mass spectrometry. Logistic regression was used to estimate the association between gestational urinary glyphosate concentrations and preterm birth, adjusted for age, race, body mass index, season of specimen collection, education level and reported organic food consumption. RESULTS:Geometric mean glyphosate concentrations were 0.07 ng/mL (95% CI: 0.04-0.13) for preterm and 0.06 ng/mL for term births (95% CI: 0.03-0.10). Fewer term whites (n=4, 31%) were in the middle (range: 0.04-0.11 ng/mL) and highest (range: 0.17-1.25 ng/mL) tertiles of glyphosate exposure than term Blacks (n=7, 54%), although the difference was not statistically significant (p=0.43). Higher urinary glyphosate was associated with lower odds of preterm birth (odds ratio=0.75, 95% confidence interval 0.16-3.68), adjusted for covariates, although also not statistically significant. The odds varied by race, with OR=0.60 (95% CI: 0.11-3.4) among whites and OR=1.40 (95% CI: 0.28-7.02) among Blacks, although the interaction was not statistically significant. CONCLUSIONS:Glyphosate exposure varied by maternal race with elevated exposure in Blacks. There was no association found between urinary glyphosate levels and preterm birth, suggesting that glyphosate may not be a preterm birth risk factor. KEYWORDS: Glyphosate, Pregnancy Outcomes, Risk Assessment, Exposure assessment-biomarkers of exposure