ADVANCEMENT OF THE SCIENCE
Lead Source Attribution by Stable Isotope Analysis in Child Risk Assessment Investigations
Summer Shaw, MPH Bureau of Environmental and
Occupational Health, Wisconsin Department of Health Services Sean Scott, PhD Wisconsin State Laboratory of Hygiene Maeve Pell, MPH Bureau of Environmental and Occupational Health, Wisconsin Department of Health Services University of Wisconsin Madison School of Medicine and Public Health Jeff Raiche-Gill Bureau of Environmental and Occupational Health, Wisconsin Department of Health Services University of Wisconsin Madison School of Medicine and Public Health
b9:r'): Lead isotope analysis (LIA) is a promising technique for identifying potential sources of lead exposure among children with lead poisoning that are not revealed via traditional lead risk assessment methods. A total of six Wisconsin children with blood lead levels (BLLs) ≥10 µg/dl were included in this case series. Lead isotope ratios from blood and environmental samples were analyzed using a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) to determine exposure source. LIA identified likely sources of lead poisoning: lead-based paint, dust, imported spices, ceremonial objects, or mixtures of these sources. LIA both corroborated findings from standard lead risk assessment and identified novel sources. LIA using high-precision MC-ICP-MS can identify and exclude sources of exposure when interpreted alongside traditional lead risk assessment approaches. Furthermore, LIA can serve as a useful tool in identifying and eliminating lead exposures in poisoning cases, particularly when traditional methods fail to identify the likely cause.
Carrie Tomasallo, MPH, PhD Bureau of Environmental and Occupational Health, Wisconsin Department of Health Services Jonathan Meiman, MD Bureau of Environmental and Occupational Health, Wisconsin Department of Health Services
used to measure isotopic fingerprints have increased discrimination due to higher sen- sitivity and precision compared with earlier applications (Gulson et al., 1995; Gwiazda et al., 2005; Millen et al., 1995; Oulhote et al., 2011; Yae et al., 1983). Given the potential of LIA for lead risk assessment, the Wisconsin Department of Health Services piloted a case series to dem- onstrate the use of high-precision LIA in identifying the primary source and second- ary contributors of lead exposure among Wisconsin children with lead poisoning.
Introduction Lead exposure early in life can lead to irre- versible harm; even low levels of lead expo- sure can aect the developing central ner- vous system and result in impaired cognitive function (Hou et al., 2013; Reuben et al., 2017). The primary intervention for a child with a case of lead poisoning is to remove the sources of lead from the child’s environment. Finding the sources, however, can be a signif- icant challenge because lead is pervasive and is present in many materials. Environmental health specialists use screening question- naires to identify likely exposure routes and X-ray fluorescence instruments to determine lead concentrations of materials in the home. Confirming the cause of lead exposure requires removing the source and observ- ing a reduction in the child’s blood lead
level (BLL), the latter of which might take months to years depending on peak BLLs and chronicity of exposure. Standard risk assessment methods can fail to identify the primary cause and result in continued lead exposure. Lead isotope analysis (LIA) holds promise for improving the accuracy of child- hood lead investigations. LIA is based on the four stable, naturally occurring isotopes of lead ( 204 Pb, 206 Pb, 207 Pb, and 208 Pb), which all have relative abundances in the Earth’s crust. Isotopes 208 Pb, 207 Pb, and 206 Pb are products of radioactive decay over geologic time. The abundances of isotopes vary given the age of the lead ore due to this radioactive decay. Isotope abundances are analyzed as Pb isotope ratios (PbIR), which are distinct and commonly called isotopic fingerprints. Advancements in technology
Methods
Investigation Protocol To be eligible for this case series, a child with a case of lead poisoning must have met the following criteria: 1) peak venous BLL ≥10 µg/dl, 2) age ≤6 years, and 3) resided in southern Wisconsin. Public health o¥cials identified and conducted data collection among six cases during May 2019–Novem- ber 2021. Local health departments obtained consent from the child’s legal guardian.
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Volume 85 • Number 9
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