Comparison of Blood Lead Concentrations in U.S. Children by Age, Race/Ethnicity, and Income

Purpose

To evaluate changes in associations between demographic factors and elevated BLLs in children, we determined the percentage of children 1–5 years of age in the various NHANES cycles with blood lead levels ≥10 μg/dL and assessed demographic trends by survey period.

Methods

Serum lead, demographic, and housing data from NHANES II (1976–1980), NHANES III (1988–1994), and the three continuous NHANES cycles (1999–2000, 2001–2002, 2003–2004) were used in these analyses. Geometric mean (GM) BLLs, 95% confidence intervals, and weighted proportions were calculated using SUDAAN software. Elevated BLLs were defined as BLLs ≥10 μg/dL.

Results

The overall GM BLLs for children 1-5 years of age during 1999–2004 was 1.9 μg/dL (95% CI: 1.8-2.0; N=4,298), an 86% reduction in levels from 1976–1980 (N=2,445) and a 40% reduction in levels from 1988–1994 (N=4,570). Consistent with these results was the remarkable reduction in the percentage of children with elevated BLLs between the periods 1976–1980 and 1988–1994 and a further decline between the 1988–1994 and 1999–2004 periods. While an inverse trend in BLLs and age was observed generally for the 1988–1994 and 1999–2004 periods, increasing age was associated with increasing BLLs from 1976–1980. For race/ethnicity, a considerably higher percentage of non-Hispanic white children had elevated BLLs during 1976–1980 whereas the percentage of non-Hispanic white and black children with BLLs ≥10 μg/dL approached similar proportions for both the 1988–1994 and 1999–2004 survey periods. More notably, the percentage of children with elevated BLLs by income varied from survey period to survey period with a consistent trend observed for the first two periods.

Conclusion

These results demonstrate not only the considerable decline in blood lead levels and the percentage of children with elevated BLLs, but also the importance of continuously evaluating which demographic characteristics impact serum lead levels in children, as the effect of these factors may shift over time.

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