Aerial Application of Mancozeb and Urinary Ethylene Thiourea (ETU) Concentrations among Pregnant Women in Costa Rica: The Infants' Environmental Health Study (ISA).

Background: Mancozeb and its main metabolite ethylene thiourea (ETU) may alter thyroid function; thyroid hormones are essential for fetal brain development. In Costa Rica, mancozeb is aerially sprayed at large-scale banana plantations on a weekly basis. Objectives: (1) evaluate urinary ETU concentrations in pregnant women living nearby large-scale banana plantations; (2) compare their estimated daily intake (EDI) with established Reference Doses (RfDs); and (3) identify factors that predict their urinary ETU concentrations. Methods: We enrolled 451 pregnant women from Matina County, Costa Rica, with large-scale banana production. We visited 445 women up to three times during pregnancy to obtain urine samples (n = 872) and information on factors that possibly influence exposure. We determined urinary ETU concentrations using liquid chromatography mass spectrometry (LCMS). Results: Pregnant women's median urinary ETU concentrations were more than five times higher than reported for other general populations. Seventy-two percent of the women had EDIs above the RfD. Women who lived closest (1st quartile, < 48 meters) to banana plantations on average had a 45% (95% CI: 23, 72%) higher urinary ETU compared with women who lived farthest away (4th quartile, ≥ 565 meter). Compared with the other women, ETU was also higher in women who washed agricultural work clothes on day before sampling (11%; 95% CI; 4.9, 17%), worked in agriculture during pregnancy (19%; 95% CI: 9.3, 29), and immigrant women (6.2%; 95% CI: 1.0, 13%). Conclusions: The pregnant women's urinary ETU concentrations are of concern, and the principal source of exposure is likely to be aerial spraying of mancozeb. The factors predicting ETU provide insight into possibilities for exposure reduction.