The association between mountaintop mining and birth defects among live births in central Appalachia, 1996-2003.

Birth defects are examined in mountaintop coal mining areas compared to other coal mining areas and non-mining areas of central Appalachia. The study hypothesis is that higher birth-defect rates are present in mountaintop mining areas. National Center for Health Statistics natality files were used to analyze 1996-2003 live births in four Central Appalachian states (N=1,889,071). Poisson regression models that control for covariates compare birth defect prevalence rates associated with maternal residence in county mining type: mountaintop mining areas, other mining areas, or non-mining areas. The prevalence rate ratio (PRR) for any birth defect was significantly higher in mountaintop mining areas compared to non-mining areas (PRR=1.26, 95% CI=1.21, 1.32), after controlling for covariates. Rates were significantly higher in mountaintop mining areas for six of seven types of defects: circulatory/respiratory, central nervous system, musculoskeletal, gastrointestinal, urogenital, and 'other'. There was evidence that mountaintop mining effects became more pronounced in the latter years (2000-2003) versus earlier years (1996-1999.) Spatial correlation between mountaintop mining and birth defects was also present, suggesting effects of mountaintop mining in a focal county on birth defects in neighboring counties. Elevated birth defect rates are partly a function of socioeconomic disadvantage, but remain elevated after controlling for those risks. Both socioeconomic and environmental influences in mountaintop mining areas may be contributing factors.