Work as a Predictor of Ethylenethiourea (ETU) Exposure During Pregnancy Among Participants Enrolled in the SEMILLA Birth Cohort Study

Background. Ethylenebisdithiocarbamates, widely used in floriculture, degrade into ethylenethiourea (ETU), a teratogen. The SEMILLA study investigates prenatal ETU exposure and infant health in Ecuador’s flower-growing region. This analysis examines whether prenatal ETU metabolite levels differ by work sector and whether maternal urinary ETU increases with longer work hours. Methods. Participants (agricultural workers, non-agricultural workers, and non-workers) provided baseline urine samples, which were processed and stored for ETU analysis. Surveys captured ETU exposure predictors. Regression models assessed associations between work sector, weekly work hours, and urinary ETU levels (specific gravity-corrected), controlling for key covariates. Results. The sample includes 111 agricultural workers (92% floriculture), 149 non-agricultural workers, and 149 non-workers. At baseline, maternal age averaged 27 years (SD = 5.8) and gestational age 15 weeks (SD = 3.2). Urinary ETUSG levels were elevated across the sample (geometric mean: 3.38 µg/L). Agricultural workers had significantly higher ETUSG levels than others (5.61 vs. 3.07 and 2.57 µg/L; p < 0.001). Among agricultural workers, ETUSG levels increased with weekly hours (B = 0.288, p = 0.001). Conclusions. Agricultural work strongly predicts higher prenatal ETU exposure, with evidence of a dose–response relationship. Research on prenatal fungicide exposure and infant health among pregnant workers is limited. Findings highlight the need for targeted interventions to protect pregnant workers and infant health.