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Roberto H. Gwiazda and Donald R. Smith

Environmental Toxicology, University of California, Santa Cruz, California, USA

Abstract

The advent of magnetic sector inductively coupled plasma-mass spectrometry (ICP-MS) allows rapid, accurate, and precise measurement of lead isotopes in environmental and biological samples at a lower cost than traditional methods. This may increase the feasibility of including lead isotope measurements as a routine tool to identify household sources of lead exposure to children. Here, we present three household case studies to illustrate how lead hazard evaluations by an environmental specialist could be supplemented with routine lead isotope analyses of potential lead sources and blood. Sampling for lead isotopes was undertaken following the U.S. Department of Housing and Urban Development regulatory guidelines for the evaluation of lead hazards in housing, and with the consideration of minimizing the additional costs associated with lead isotope measurements. The range of isotopic ratios within a single residence was large enough to allow the characterization of different lead sources, particularly when both major (e.g., ²⁰⁷Pb/²⁰⁶Pb) and minor (e.g., ²⁰⁶Pb/²⁰⁴Pb) isotope ratios were considered. These cases illustrate the utility of the lead isotope method to identify main source(s) of lead exposure to the child ; discard unlikely sources of exposure to the child ; point to sources of lead to dust ; and substantiate or refine the environmental assessment based exclusively on lead concentrations and loadings. Thus, a more effective evaluation of household lead hazards would likely benefit from considering a) lead concentrations and loadings in and around the household environment ; b) all isotopic ratios of potential lead sources within that environment ; and c) information about behavioral habits, as well as an evaluation of viable pathways of exposure to the child. Key words: blood lead, ICP-MS, lead exposure, lead hazard assessment, lead isotopes, lead paint. Environ Health Perspect 108:1091-1097 (2000) . [Online 27 October 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p1091-1097gwiazda/ abstract.html

Address correspondence to R. Gwiazda, ETOX, University of California, 1156 High Street, Santa Cruz, CA 95064 USA. Telephone: (831) 459-3347. Fax: (831) 459-3524. E-mail: gwiazda@aphrodite.ucsc.edu.

We thank the study subjects and families, C. Sparks and C. Fuller for case referral and lead hazard assessment, and D. Woolard and R. Franks for analytical assistance.

This work was supported by the University of California Toxic Substances Research and Teaching Program, the Office of Lead Hazard Control at the U.S. Department of Housing and Urban Development, and the Institute of Marine Sciences, University of California, Santa Cruz.

Received 4 February 2000 ; accepted 9 June 2000.