Blood lead levels and major depressive disorder, panic disorder, and generalized anxiety disorder in US young adults

Context: Lead is a ubiquitous neurotoxicant, and adverse cognitive and behavioral effects are welldocumented in children and occupationally exposed adults but not in adults with low environmental exposure. Objective: To investigate the association of current blood lead levels with 3 common psychiatric disorders - major depression, panic, and generalized anxiety - in young adults. Design: Cross-sectional epidemiologic survey. Setting: Nationally representative sample of US adults. Participants: A total of 1987 adults aged 20 to 39 years who responded to the National Health and Nutrition Examination Survey (1999-2004). Main Outcome Measures: Twelve-month DSM-IV criteria - based diagnoses of major depressive disorder, panic disorder, and generalized anxiety disorder assessed using the Composite International Diagnostic Interview. Results: The mean (SD) blood lead level was 1.61 (1.72) μg/dL (range, 0.3-37.3 μg/dL) (to convert to micromoles per liter, multiply by 0.0483). Increasing blood lead levels were associated with higher odds of major depression (P=.05 for trend) and panic disorder (P=.02 for trend) but not generalized anxiety disorder (P=.78 for trend) after adjustment for sex, age, race/ethnicity, education status, and poverty to income ratio. Persons with blood lead levels in the highest quintile had 2.3 times the odds of major depressive disorder (95% confidence interval [CI], 1.13-4.75) and 4.9 times the odds of panic disorder (1.32-18.48) as those in the lowest quintile. Cigarette smoking was associated with higher blood lead levels and outcome, but models that excluded current smokers also resulted in significantly increased odds of major depression (P=.03 for trend) and panic disorder (P=.01 for trend) with higher blood lead quintiles. Conclusions: In these young adults with low levels of lead exposure, higher blood lead levels were associated with increased odds of major depression and panic disorders. Exposure to lead at levels generally considered safe could result in adverse mental health outcomes.