Lead-contaminated soil abatement and urban children's blood lead levels
M. Weitzman, A. Aschengrau, D. Bellinger, R. Jones, J. S. Hamlin and A. Beiser
Department of Pediatrics, University of Rochester, School of Medicine and Dentistry, NY.
OBJECTIVE--To test the hypothesis that a reduction of 1000 ppm or more of
lead in soil accessible to children would result in a decrease of at least
0.14 mumol/L (3 micrograms/dL) in blood lead levels. SETTING--Urban
neighborhoods with a high incidence of childhood lead poisoning and high
soil lead levels. DESIGN--Randomized controlled trial of the effects of
lead-contaminated soil abatement on blood lead levels of children followed
up for approximately 1 year after the intervention. PATIENTS--A total of
152 children less than 4 years of age with venous blood lead levels of 0.34
to 1.16 mumol/L (7 to 24 micrograms/dL). Children were largely poor and had
a mean age at baseline of 32 months, a mean blood lead level of 0.60
mumol/L (12.5 micrograms/dL), and a median surface soil lead level of 2075
ppm. INTERVENTIONS--Children were randomized to one of three groups: the
study group, whose homes received soil and interior dust abatement and
loose paint removal; comparison group A, whose homes received interior dust
abatement and loose paint removal; and comparison group B, whose homes
received only interior loose paint removal. MAIN OUTCOME MEASURES--Change
in children's blood lead levels from preabatement levels to levels
approximately 6 and 11 months after abatement. RESULTS--The mean decline in
blood lead level between preabatement and 11 months after abatement was
0.12 mumol/L (2.44 micrograms/dL) in the study group (P = .001), 0.04
mumol/L (0.91 microgram/dL) in group A (P = .04), and 0.02 mumol/L (0.52
microgram/mL) in group B (P = .31). The mean blood lead level of the study
group declined 0.07 mumol/L (1.53 micrograms/dL) more than that of group A
(95% confidence interval [CI], -0.14 to -0.01 mumol/L [-2.87 to -0.19
micrograms/dL]) and 0.09 mumol/L (1.92 micrograms/dL) more than group B
(95% CI, -0.16 to -0.03 mumol/L [-3.28 to -0.56 micrograms/dL]). When
adjusted for preabatement lead level, the 11-month mean blood lead level
was 0.06 mumol/L (1.28 micrograms/dL) lower in the study group as compared
with group A (P = .02) and 0.07 mumol/L (1.49 micrograms/dL) lower than in
group B (P = .01). The magnitude of the decline independently associated
with soil abatement ranged from 0.04 to 0.08 mumol/L (0.8 to 1.6
micrograms/dL) when the impact of potential confounders, such as water,
dust, and paint lead levels, children's mouthing behaviors, and other
characteristics, was controlled for. CONCLUSIONS--These results demonstrate
that lead-contaminated soil contributes to the lead burden of urban
children and that abatement of lead-contaminated soil around homes results
in a modest decline in blood lead levels. The magnitude of reduction in
blood lead level observed, however, suggests that lead-contaminated soil
abatement is not likely to be a useful clinical intervention for the
majority of urban children in the United States with low-level lead
exposure.
