Perinatal exposure to chlordecone, thyroid hormone status and neurodevelopment in infants: The Timoun cohort study in Guadeloupe (French West Indies)

• Persistent contamination by chlordecone insecticide affects French West Indies.
• Chlordecone was assayed in cord blood and breast milk.
• Thyroid hormones were determined in 3-months old children.
• Thyroid hormones disruption was observed after prenatal exposure among boys only.
• Postnatal exposure was associated with thyroid hormones disruption in both sexes.

BackgroundPerinatal exposure to endocrine-disrupting chemicals may affect thyroid hormones homeostasis and impair brain development. Chlordecone, an organochlorine insecticide widely used in the French West Indies has known estrogenic and progestin properties, but no data is available, human or animal, on its action on thyroid hormone system.ObjectivesOur aim was to evaluate the impact of perinatal exposure to chlordecone on the thyroid hormone system of a sample of infants from the Timoun mother–child cohort in Guadeloupe and their further neurodevelopment.MethodsChlordecone was measured in cord blood and breast milk samples. Thyroid stimulating hormone (TSH), free tri-iodothyronine (FT3), free thyroxine (FT4) were determined in child blood at 3 months (n=111). Toddlers were further assessed at 18 months using an adapted version of the Ages and Stages Questionnaire (ASQ).ResultsCord chlordecone was associated with an increase in TSH in boys, whereas postnatal exposure was associated with a decrease in FT3 overall, and in FT4 among girls. Higher TSH level at 3 months was positively associated with the ASQ score of fine motor development at 18 months among boys, but TSH did not modify the association between prenatal chlordecone exposure and poorer ASQ fine motor score.ConclusionsPerinatal exposure to chlordecone may affect TSH and thyroid hormone levels at 3 months, differently according to the sex of the infant. This disruption however did not appear to intervene in the pathway between prenatal chlordecone exposure and fine motor child development.