Association between blood lead exposure and mental health in pregnant women: Results from the Japan environment and children's study.

OBJECTIVE: Although environmental lead exposure has decreased, several studies have shown that low-level lead exposure can result in adverse psychological symptoms. However, few studies have examined lead neurotoxicity in pregnant women. We investigated the association between lead exposure and psychological symptoms in pregnant women, and between socio-economic status and blood lead levels. METHODS: Blood lead levels were measured in 17,267 pregnant women in the Japan Environment and Children's Study. Odds ratios (ORs) for high blood lead levels were calculated using multinomial logistic regression. Psychological symptoms were assessed using the Kessler Psychological Distress Scale (K6). ORs for depression (K6 ≥ 13 or ≥5) were calculated using logistic regression with adjustment for potential confounders. RESULTS: The geometric mean of whole blood lead levels was 0.58 µg/dl (range 0.14-6.75 µg/dl). Higher blood lead levels were associated with older age (OR 1.79, 9 5% confidence interval [CI] 1.46-2.19), unmarried status (OR 1.75, 95 % CI 1.31-2.33), lower household income (OR 1.76, 95 % CI 1.38-2.24), and lower educational attainment (OR 1.34, 95 % CI 1.20-1.48). The percentage of women with K6 scores ≥13 and ≥5 was 3 % and 28.2 %, respectively. There was no significant association between lead exposure and K6 score (K6 ≥ 13: OR 1.00, 95 % CI 0.76-1.32; K6 ≥ 5: OR 0.98, 95 % CI 0.88-1.09). CONCLUSION: Our results indicate a small but significant association between higher blood lead levels and lower socio-economic status in a population with low blood lead levels, but no association between low-level lead exposure and psychological symptoms.