Use of lead isotope ratios to identify sources of lead exposure in Alaska Natives

Abstract

OBJECTIVES: Although banned nationwide for waterfowl hunting, lead shot is still used for hunting in regions of Alaska. Consumption of birds hunted with lead shot may be a route of human lead exposure in susceptible populations. The Centers for Disease Control and Prevention (CDC) and Alaskan health officials conducted a cross-sectional exposure assessment and used isotope ratios (IR) to test that assumption.STUDY DESIGN: Cross-sectional exposure assessment study.METHODS: We compared isotopic profiles of blood lead in Alaska Native women from Bethel (n = 10) and Barrow (n = 10) to lead shot samples purchased from the respective regions. To evaluate the source of lead for the buckshot, we evaluated IR profiles for lead mineral and ore from a smelter in Torreon, Mexico, a suspected source of origin for the lead.RESULTS: The lead IRs for the blood lead differed significantly from the lead shot IRs (p > 0.001); thus, lead shot is unlikely to be the sole source of lead exposure of public health significance in participants of this study. Overlap in IRs for the lead shot and blood lead existed for 6 (30%) of the women from Bethel and Barrow; however, no correlation was noted between lead levels and the IRs for the blood lead. IR profiles for lead mineral and ore from Mexico were substantially different from the IRs of lead shot from Alaska, confirming that buckshot in this study is unlikely to originate from the Mexican smelter.CONCLUSIONS: Lead shot from the manufacturer in this study does not appear to be the sole source of lead exposure in most participants; nonetheless, lead shot could yet be a potential source of exposure in some populations, possibly those whose diet consists of game hunted with lead shot.