Association of heavy metals with measures of pulmonary function in children and youth: Results from the National Health and Nutrition Examination Survey (NHANES)

INTRODUCTION: Exposure to cadmium, cobalt, lead, and manganese has been associated with decreased pulmonary function in adults. Little is known about the magnitude of these associations among children in the United States. OBJECTIVES: We evaluated cross-sectional associations of blood and urinary concentrations of cadmium, cobalt, lead, and manganese with pulmonary function measures [forced expiratory volume in one second (FEV1; milliliters), forced vital capacity (FVC; milliliters), ratio of FEV1 to FVC (FEV1:FVC), and mid-exhalation forced expiratory flow rate (FEF 25-75%; milliliters/second)] in a sample of 1234 6-17 year olds, who participated in the 2011-2012 survey cycle of the National Health and Nutrition Examination Survey (NHANES). METHODS: Survey-weighted linear regression was used to estimate beta coefficients and 95% confidence intervals (CIs) for the associations between metal exposure tertiles or quartiles and pulmonary function test parameters, with adjustment for relevant covariates. RESULTS: Blood manganese concentration was inversely associated with FVC (β for highest versus lowest quartile = -97.1, 95% CI = -230.6, 36.4; p for trend = 0.03). Urinary manganese was inversely associated with FEV1:FVC and FEF 25-75% (p for trend = 0.05 and 0.02, respectively). Urinary lead was inversely associated with FEF 25-75% (p for trend = 0.01). The associations between blood manganese and both FEV1 and FVC differed by age (p for interaction = 0.04 and 0.04, respectively), indicating an inverse trend that was strongest among older youth. CONCLUSIONS: Environmental exposure to manganese and lead may adversely impact the pulmonary function of young people in the United States. Our findings highlight a need to prioritize children's environmental health and evaluate these associations prospectively.