TABLE 1

Distribution of BLLs According to Selected Demographic Characteristics, Children Aged 1 to 5 years, NHANES 1999–2004

nGeometric Mean (95% CI), μg/dL<1 μg/dL, % (95% CI)1 to <2.5 μg/dL, % (95% CI)2.5 to <5 μg/dL, % (95% CI)5 to <7.5 μg/dL, % (95% CI)7.5 to <10 μg/dL, % (95% CI)≥10 μg/dL, % (95% CI)
Overall25321.9 (1.8–2.0)a14.0 (11.6–16.6)b55.0 (52.1–57.9)23.6 (21.1–26.1)4.5 (3.3–5.9)1.5 (1.0–2.1)1.4 (1.0–2.0)b
Gender
    Girl12111.9 (1.7–2.0)a14.1 (10.8–17.7)b54.5 (51.1–57.8)23.9 (20.3–27.8)4.5 (3.3–5.8)1.4 (0.8–2.3)1.7 (0.9–2.6)b
    Boy13211.9 (1.7–2.0)a14.0 (11.4–16.7)b55.5 (51.4–59.5)23.2 (20.3–26.3)4.6 (3.0–6.5)1.5 (0.9–2.3)1.3 (0.7–2.6)b
Agec
    1–2 y12312.1 (2.0–2.2)a,c10.6 (7.7–13.9)b,d51.0 (46.7–55.3)c27.9 (24.9–31.0)d6.7 (5.0–8.6)d1.4 (0.8–2.2)2.4 (1.4–3.5)b,d
    3–5 y13011.7 (1.6–1.9)a,c16.2 (12.9–19.9)b,d57.6 (53.8–61.4)c20.7 (17.9–23.7)d3.1 (1.9–4.6)d1.5 (0.8–2.3)0.9 (0.4–1.5)e,b,d
Race/ethnicityc
    Non-Hispanic black7552.8 (2.5–3.0)a,f,g4.0 (2.5–5.7)f,g42.5 (37.8–47.2)f,g36.2 (33.1–39.3)f,g9.4 (6.9–12.2)f,g4.6 (3.0–6.5)f,g3.4 (1.8–5.5)b
    Mexican American8121.9 (1.7–2.0)a,f10.9 (8.6–13.4)b,f,h61.0 (56.9–65.1)f22.1 (18.0–26.5)f3.4 (2.2–5.0)f1.3 (0.6–2.2)f1.2 (0.4–2.6)a,e
    Non-Hispanic white7311.7 (1.6–1.8)a,g17.6 (14.0–21.5)b,g,h57.1 (52.4–61.7)g19.7 (16.1–23.5)g3.6 (1.9–5.8)g0.8 (0.3–1.6)e,g1.2 (0.6–2.0)b
PIRc
    ≤1.313022.4 (2.2–2.5)a,c6.7 (4.6–9.2)b,d49.3 (44.9–53.7)d32.5 (28.6–36.4)d6.9 (5.2–8.8)d2.8 (1.7–4.1)d1.8 (1.1–2.7)b
    >1.310701.5 (1.4–1.6)a,c19.9 (16.3–23.8)b,d60.4 (56.9–63.8)d16.0 (12.9–19.3)d2.3 (1.2–3.7)d0.6 (0.1–1.4)d,e0.8 (0.3–1.6)b,e
Medicaid statusc
    Yes9902.6 (2.2–2.5)a,c5.8 (3.6–8.6)b,d49.5 (45.2–53.8)d32.4 (28.4–36.5)d7.7 (5.7–10.0)d2.7 (1.6–4.2)d1.9 (0.9–3.1)b
    No15001.7 (1.6–1.8)a,c17.6 (14.0–21.4)b,d57.9 (54.3–61.5)d19.3 (16.2–22.6)d3.2 (2.1–4.6)d0.9 (0.4–1.6)d,e1.1 (0.6–1.7)b
Year housing built (risk of lead exposure)c,i
    Low risk6741.5 (1.3–1.6)a,j,k22.1 (17.3–27.3)b,k62.8 (57.4–68.1)k13.0 (9.6–16.8)h,k1.4 (0.6–2.5)e,k0.3 (0.1–0.4)k0.4 (0.0–1.3)e,k
    Medium risk5551.8 (1.7–1.9)a,j,l14.4 (10.2–19.3)b,l57.9 (52.0–63.8)23.4 (18.5–28.6)h2.3 (1.1–3.9)e,l1.1 (0.4–2.1)e0.8 (0.3–1.7)b,e
    High risk3352.5 (2.2–2.8)a,k,l5.5 (2.4–9.7)e,k,l47.4 (40.2–54.7)k32.0 (25.0–39.4)k8.7 (5.3–12.9)k,l3.1 (1.5–5.2)k3.3 (1.5–5.8)e,k
    Not known9682.3 (2.1–2.6)7.6 (5.2–10.4)46.3 (40.6–52.0)33.2 (29.5–37.0)8.2 (5.9–10.7)2.4 (1.3–4.0)2.3 (1.1–3.8)
  • a Difference between 1988–1991 and 1999–2004 statistically significant at P < .05 after Bonferroni adjustment.

  • b Difference between 1988–1991 and 1999–2004 within lead categories BLL <1 μg/dL and/ BLL ≥10 μg/dL statistically significant at P < .05 after Bonferroni adjustment.

  • c Differences between strata for categorical blood lead variable in 1999–2004 statistically significant at P < .05.

  • d Difference between strata in 1999–2004 statistically significant at P < .05.

  • e Relative SE of point estimate ≥30%; does not meet standard of statistical reliability and precision.

  • f Difference between non-Hispanic black children and Mexican American children in 1999–2004 statistically significant at P < .05 after Bonferroni adjustment.

  • g Difference between non-Hispanic black children and non-Hispanic white children in 1999–2004 statistically significant at P < .05 after Bonferroni adjustment.

  • h Difference between Mexican American children and non-Hispanic white children in 1999–2004 statistically significant at P < .05 after Bonferroni adjustment.

  • i Risk of lead exposure by year housing built defined as follows:

    NHANES 1999–2004: low risk, built 1978 and later; medium risk, built between 1950 and 1977; high risk, built before 1950.

    NHANES III phases 1 and 2: low risk, built 1974 and later; medium risk, built between 1946 and 1973; high risk, built before 1946.

  • j Difference between low-risk housing and medium-risk housing in 1999–2004 statistically significant at P < .05 after Bonferroni adjustment.

  • k Difference between low-risk housing and high-risk housing in 1999–2004 statistically significant at P < .05 after Bonferroni adjustment.

  • l Difference between medium-risk housing and high-risk housing in 1999–2004 statistically significant at P < .05 after Bonferroni adjustment.