Firearm-related lead exposure and pediatric lead levels in Massachusetts: A decade of evidence (2010-2019).

The US has more firearms than any other country in the world and uses lead ammunition almost exclusively. Lead exposure is a significant public health concern and children are at the greatest risk given their exposure to take-home lead. Firearm-related take-home lead exposure may be one of the greatest influences on elevated pediatric blood lead levels. For this ecological and spatial investigation of the relationship between firearm licensure rates as a proxy for firearm-related lead exposure and prevalence of children with blood lead levels ≥5 μg/dL in 351 cities/towns in Massachusetts, we used 10 years of data (2010-2019). We examined this relationship against other known contributors to pediatric lead exposure including old housing stock (lead paint/dust), occupations, and lead in water. Pediatric blood lead levels were positively correlated with licensure, poverty, and certain occupations and negatively correlated with lead in water and police or firefighter employment. Firearm licensure was a major significant predictor of pediatric blood lead alone (β = 0.13; 95% CI, 0.10, 0.17) and across all regression models. The final model predicted over half the variation in pediatric blood lead (Adjusted R = 0.51). Negative binomial analysis found cities/towns with more firearms had higher pediatric blood lead levels (highest quartile fully adjusted prevalence ratio ((aPR) = 1.18; 95% CI, 1.09, 1.30) with a significant increase in pediatric blood lead per increase in firearms (p < 0.001). There were no significant spatial effects, suggesting that although there could be other factors impacting elevated pediatric blood lead, they are unlikely to influence spatial associations. Our paper provides compelling evidence of a potential and dangerous link between lead ammunition and child blood lead levels and is the first to do so using multiple years' worth of data. More research is required to substantiate this relationship on the individual-level and into prevention/mitigation.