Description:
Background: Flaking paint, past leaded gasoline use, smelter and mining operations, have contributed to lead in soils. Leaded paint in older homes and lead contaminated soil are the leading sources of lead exposure for children in the United States.
Objectives: The purpose of this review is to evaluate the soil lead contribution to blood lead levels. Methods: We evaluated data from Agency for Toxic Substances and Disease Registry (ATSDR) reports published between 1985 and 2005 on Superfund or similar locations where soil and blood lead data were collected. Those data, available from 127 reports at 77 locations, represented 22,805 people (65% children) in 30 states. We used maximum blood lead levels (BLLs) for the analysis because median or mean values were mostly unavailable in ATSDR's HazDat database. Further, the mean blood lead levels (BLLs) for the reports where data were available were highly correlated with the maximum BLLs (n=46; Spearman correlation coefficient r =0.77; p-value=<0.0001).
Results: One hundred reports had a maximum BLL equal to or greater than 10 µg/dL and 27 reports were less than 10 µg/dL. There was no statistically significant difference between the median of the maximum soil lead levels where the maximum BLLs were ≥10µg/dL [27,988 parts per million (ppm); 95% CI: 16,000- 33,100] and BLLs <10µg/dL [25,500 ppm; 95% CI: 12,669- 48,000]. The findings indicate that in these sites, there is no statistically significant correlation between the maximum BLLs and maximum soil lead levels for both children and adults (Spearman correlation coefficient r=0.04; p-value =0.6283; n= 127 events).
Conclusions: Our review of these data suggests that there does not appear to be a relationship between BLLs and soil lead levels for these sites. Since all lead-contaminated soil sites are not alike and absorption is dependant on exposure factors (e.g., bioavailability, particle size, soil dose estimates) more work may be needed to standardize the capture of meaningful information (i.e., exposure factors) in exposure databases. |