Prenatal exposure to persistent organic compounds and their association with anogenital distance in infants.

Research Question: What is the association between prenatal exposure to persistent organic pollutants, separately and combined, and anogenital distance (in-utero endocrine disruption marker).

Design: A cohort study conducted in Sonora, Mexico. Blood concentrations of polychlorobiphenyls (PCB) 28, 74, 118, 138/158, 153, 170, 180 and the isomers of dichlorodiphenyltrichloroethane (DDT) and its metabolites were determined in women in the third trimester of pregnancy; three variants of anogenital distance were measured on five occasions during the first year of life of their infants: 82 girls (402 observations) and 74 boys (356 observations).

Results: Boys had negative and significant associations between anogenital distance/height and the concentrations of PCB 28 (beta = - 0.005;P = 0.006), PCB 74 (beta = - 0.003;P = 0.013), and PCB 170 (beta = - 0.005;P = 0.001) when analysed individually. Negative and significant associations were also found using statistical models applied to mixtures of compounds. The latter associations were sometimes larger in magnitude and significance, suggesting a possible potentiation of the compounds. No associations were observed between anogenital distance and DDT in either sex or with PCB in girls.

Conclusions: The decreased anogenital distance associated with prenatal exposure to the persistent organic pollutants, observed consistently in different analyses, suggests an under-masculinizing effect of these environmental pollutants in boys.