Graduate Defense: Jianna Gimenez

Thesis Information

Title: Assessing Chronic Exposure To Glyphosate Using Urine Analysis

Program: Master of Public Health

Advisor: Dr. Cynthia Curl, Public and Population Health

Committee Members: Dr. Carly Hyland, Public and Population Health and Dr. Uwe Reischl, Public and Population Health

Abstract

The herbicide glyphosate is the most heavily used agricultural chemical in the world, and exposure has been linked to carcinogenic and reproductive effects, although this remains controversial. Glyphosate has a short biologic half-life, challenging the assessment of associations between chronic exposure and potential health effects. Long-term glyphosate exposure has often been evaluated using a single urine sample, potentially resulting in exposure misclassification leading to systematic underestimation of the association between glyphosate exposure and health outcomes. To determine the minimum number of urine samples required to accurately characterize chronic glyphosate exposure during pregnancy, we collected 453 urine samples from a cohort of 40 pregnant women (average samples per participant = 11) . We calculated an intraclass correlation coefficient of 0.18, suggesting higher within- than between- participant variability. Additionally, we assigned each participant to a quartile of exposure using specific gravity-adjusted geometric mean glyphosate concentrations. Using bootstrap resampling, we will determine the minimum number of urine samples required to accurately assess glyphosate exposure over a six month period. These results will inform future researcher regarding the number of urine samples required to accurately characterize glyphosate exposure throughout pregnancy.