Associations of prenatal and early childhood mercury exposure with autistic behaviors at 5 years of age: The Mothers and Children's Environmental Health (MOCEH) study

摘要

Background: Although mercury is an established neurotoxin, only few longitudinal studies have investigated the association between prenatal and early childhood mercury exposure and autistic behaviors. Methods: We conducted a longitudinal cohort study using an ongoing prospective birth cohort initiated in 2006, wherein blood mercury levels were measured at early and late pregnancy; in cord blood; and at 2 and 3 years of age. We analyzed 458 mother-child pairs. Autistic behaviors were assessed using the Social Responsiveness Scale (SRS) at 5 years of age. Both continuous SRS T-scores and T-scores dichotomized by a score of ≥60 or <60 were used as outcomes. Results: The geometric mean of mercury concentrations in cord blood was 5.52 μg/L In adjusted models, a doubling of blood mercury levels at late pregnancy (0 = 1.84,95% confidence interval [CI]: 039,329), in cord blood (P = 224,95% CI: 022,427), and at 2 years (β = 2.12,95% CI: 054,3.70) and 3 years (β = 2.80,95% CI: 0.89, 4.72) of age was positively associated with the SRS T-scores. When the SRS T-scores were dichotomized, we observed positive associations with mercury levels at late pregnancy (relative risk [RR] = 1.31,95% CI: 1.08,1.60) and in cord blood (RR = 1.28,95% d: 1.01,1.63). Conclusion: We found that blood mercury levels at late pregnancy and early childhood were associated with more autistic behaviors in children at 5 years of age. Further study on the long-term effects of mercury exposure is recommended.