1. Review of Soil Lead near Hazardous Waste Sites and Blood Lead Levels in People Living Near Them
Diane Jackson, PE, Hatice Zahran, MD, MPH, Greg Zarus, MS
Agency for Toxic Substances and Disease Registry and National Center for Environmental Health,
Background/Objectives
Figure 3 shows the maximum soil concentrations detected vs. the maximum BLL.
The main data source was ATSDR’s Hazardous Substance Release/Health Effects Database (HazDat). HazDat was created to store information on the release of hazardous substances from Superfund sites or from emergency events. HazDat included the following:
site characteristics activities and site events contaminants found
 contaminant media  maximum concentration levels
biomonitoring maximum and average concentrations  exposure routes
physical hazards  impact on population community health concerns
ATSDR public health threat categorization recommendations
HazDat data was abstracted from ATSDR’s published documents. HazDat has since been replaced by a new database.
BACKGROUND: Flaking paint, past leaded gasoline use, smelter and mining operations, have contributed to lead in soils (Levin et al. 2008). Leaded paint in older homes and lead contaminated soil are the leading sources of lead exposure for children in the United States (Levin et al. 2008; USEPA 2009). 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 (64% children) in 30 states. Figure 1 shows the population breakdown by group and Figure 2 lists the type of Superfund site.
We used maximum blood lead levels (BLLs) for the analysis because median or mean values were mostly unavailable in ATSDR’s Hazardous Substance Release/Health Effects Database (HazDat). 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
Maximum BLL ≥ 10 µg/dL =100 Reports Max BLL <10 µg/dL = 27 Reports
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, ,100] and BLLs <10µg/dL [25,500 ppm; 95% CI: 12, ,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.
Table 1. Selected percentiles of soil lead concentrations (ppm) for sites with
Maximum Blood Lead Levels (BLLs)
Sample Description
# samples/sites
# people tested
Range1 (ppm)
25th
(95%CIs)
50th
75th
90th
95th
Maximum soil sites with blood lead sampling.
127 reports/
77 sites
22,805 people2
,000
6,300
(3,200-11,450)
26,300
(16,500-33,100)
50,800 (37,000-62,000)
112,000 (65,600 – 150,000)
150,000
(114,00– 300,000)
Maximum soil levels for sites with a maximum BLL ≥10 ug/dL.
100 reports/
61 sites3
22,137 people
,000
6,053 (2,930– 11,000)
27,988 (16, ,100)
50,900 (37, ,600)
109,500 (65, ,000)
139,000 (112, ,000)
Maximum soil levels for sites with a maximum BLL <10 ug/dL
27 reports/
20 sites3
668 people
,000
8,000
(3, ,385)
25,500
(12, ,000)
48,000
(26, ,000)
NA*
1All of the soil concentrations are from the maximum soil concentrations reported for the site.
2Data on number of people sampled was missing for 16.5% of the events (21/127). This number represents the minimum.
3# sites does not add up to 77 because some sites had more than one report.
*Sample size was too small to calculate with accuracy
The Spearman correlation coefficient for the Maximum BLL vs. Maximum soil lead concentration (n= 127 reports) was r=0.04 (p-value =0.6283); therefore not correlated.
References
ATSDR (Agency for Toxic Substances and Disease Registry) Hazardous Substance Release/Health Effects Database (HazDat). No longer available.
Levin R, Brown MJ, Kashtock ME, Jacobs DE, Whelan EA, Rodman J, et al Lead exposure in U.S. Children, 2008: implications for prevention.
Environ Health Perspect 116:1285–1293 (2008). doi: /ehp available via [Online 19 May 2008]. [Accessed 26 January 2009]
USEPA (U.S. Environmental Protection Agency) Lead in Paint, Dust, and Soil. Available: [Accessed on 20 January 2009].
Contacts
For more information, contact:
Diane Jackson
Ph:
Spearman correlation coefficient for Mean BLL vs. Maximum BLL for adults and children
Spearman correlation coefficients
n, r (p-value)
All (n=127)
46, 0.77 (<0.0001)
Children (n=83)
26, 0.86 (<0.0001)