Identification of Lead Sources in California Children using the Stable Isotope Ratio Technique

Abstract

Two case studies are presented which apply the lead isotope ratio method to the identification of lead sources in 12 Oakland, California children. One study examined lead sources in 10 children, ages 3 to 15 yr, living together as an extended family in dilapidated housing close to a busy freeway. Eight children had elevated blood lead levels (greater than or equal to 30 micrograms/dl) and 6 children also had elevated erythrocyte protoporphyrin levels (greater than or equal to 50 micrograms/dl). A second case study examined 2-yr-old male twins, both with elevated blood lead and erythrocyte protoporphyrin levels, living in a modest, but well maintained inner city duplex apartment. Paint and surface soil samples collected in and around both households had high lead concentrations. Paint concentrations ranged from 2.9 to 273 mg/g and surface soil concentrations from 0.48 to 7.1 mg/g. The isotopic ratios of lead in the blood of these children were close to the average lead ratios of paints from exterior walls and to the lead ratios of surface soils in adjacent areas where the children played. In both case studies, the data suggest that the lead in the soil was derived mainly from weathering of lead-based exterior paints and that the lead-contaminated soil was a proximate source of lead in the blood of the children.

Isotope Ratio Analysis of Lead in Blood and Environmental Samples by Multi-collector Inductively Coupled Plasma Mass Spectrometry

“…[6][7][8] In these studies, thermal ionization mass spectrometry (TIMS) was used, and paint and gasoline were indicated as sources in those days. Multi-collector ICP mass spectrometry (MC-ICPMS) is known to possess excellent precision of isotope measurement, as TIMS does, and it can potentially be applied to the childhood Pb issue as well.…”

The development of applied action levels for soil contact: a scenario for the exposure of humans to soil in a residential setting.

“…A reduction of airborne Pb levels did not result in appreciable reduction of PbB content in children living adjacent to a smelter (26,27). The Pb content of blood correlated with the Pb content of house dust, soil, or outdoor paint, but not with indoor paint (10,22).…”

“…These areas are characterized by elevated levels of Pb in the environment. Numerous studies have linked the PbB content of young children with the Pb content of soil or house dust (9,10,12,(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)25,26). These studies indicate that exposure to Pb via contaminated soil or house dust is responsible for a significant amount of the Pb burden in children.…”

“…A variety of studies have correlated PbB levels with airborne Pb or Pb in weathered paint (15,16,21,22,26). Several studies have indicated that the exposure to Pb occurred via contact with soil and not directly from air or paint.…”

Lead Isotopes as a Supplementary Tool in the Routine Evaluation of Household Lead Hazards

“…The lead isotope methodology using thermal ionization mass spectrometry (TIMS) has been used to identify sources of exposure to humans (21)(22)(23)(24)(25)(26)(27)(28). This technique is potentially the most accurate indicator of the source(s) of lead to the child because there are often measurable differences in lead isotope abundances between different sources of lead exposure.…”