STABLE LEAD-ISOTOPE PROFILES IN SMELTER AND GENERAL URBAN COMMUNITIES- A COMPARISON OF ENVIRONMENTAL AND BLOOD MEASURES

High-precision lead isotope ratios and lead concentrations have been c ompared statistically and graphically in women of child-bearing age (n = 77) from two smelter communities and one general urban community to evaluate the relative contributions to blood lead of tissue lead stor es and lead from the contemporaneous environment (soil, floor dust, in door airborne dust, water, food). Blood lead (PbB) contents were gener ally low (e.g. <10 mu g dL(-1)). Statistically significant isotopic di fferences in blood and environmental samples were observed between the three cities although isotopic differences in blood for individual su bjects living in close proximity (similar to 200 m radius) was as larg e as the differences within a city. No single environmental measure do minated the biological isotope profile and in many cases the low level s of blood lead meant that their isotopic profiles could be easily per turbed by relatively small changes of environmental exposure. Apportio ning of sources using lead isotopes is possibly not feasible, nor cost effective, when blood lead levels are <5 mu g dL(-1). Interpretations based on statistical analyses of city-wide data do not give the same conclusions as when the houses are considered individually. Aggregatin g data from multiple subjects in a study such as this obscures potenti ally useful information. Most of the measures employed in this study, and many other similar studies, are markers of only short-to-medium in tegration of lead exposure. Serial sampling of blood and longer sampli ng times, especially for household variables, should provide more mean ingful information.