Source and pathways of lead in humans from the Broken Hill mining community; an alternative use of exploration methods

Abstract

To assist in recommendations for the most suitable lead abatement policies in Broken Hill, New South Wales, Australia, knowledge of the sources and pathways of the lead into humans is critical. We have approached these problems using the lead isotope fingerprinting method, combined with mineral speciation and bioavailability tests, approaches which have in the past been largely applied to mineral exploration.High precision lead isotope ratio measurements and lead contents were determined by thermal ionization mass spectrometry on biological samples (blood, urine) and environmental samples from 27 families, encompassing 60 children, 41 female adults, and 17 male adults. Environmental samples analyzed (not from every household) included soils, gutter sweepings, ceiling dust, vacuum cleaner dust, long-term dust, surface dust wipes, external and internal air, food, water, and gasoline.Sources of lead have been identified in the blood of children, using lead isotopes, with dominant contributions from the Broken Hill orebody, but with individual cases having a dominant source of lead from gasoline or paint. Nevertheless, of 28 children with a blood lead level (Pb B ) > 15 mu /dl, approximately 30 percent have more than 50 percent of their Pb B from sources other than orebody lead. Female adults generally have a low Pb B , 100 percent (mean = 47 + or - 38%, n = 5) from vacuum cleaner dusts. Thus the currently suggested amounts of approximately 100 mg/d ingested soil (dirt) and dust for a Broken Hill child can readily account for the elevated lead levels compared with the amounts for children in many other mining communities. Based on these investigations it is possible to construct a flow sheet of sources and pathways for the lead into humans at Broken Hill on which to base correct remedial actions.