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Table 1 Demographic characteristics, mean blood lead concentrations, reading and math ISAT scores of Chicago cohort

From: The impact of low-level lead toxicity on school performance among children in the Chicago Public Schools: a population-based retrospective cohort study

Characteristic n (%) B-Pb (μg/dL) mean ± SD Reading score ISAT mean ± SD Math score ISAT mean ± SD Reading failure % Math failure %
Overall 47,168 (100) 4.81 ± 2.22 154.9 ± 14.8 156.9 ± 14.2 14.6 14.5
Gender       
Male 23,746 (50) 4.85 ± 2.23 153.3 ± 14.8 156.6 ± 14.7 18.0 16.5
Female 23,413 (50) 4.77 ± 2.21 156.5 ± 14.6 157.2 ± 13.7 11.1 12.4
Race/Ethnicity       
Non-Hispanic black 30,020 (64) 5.25 ± 2.20 152.5 ± 14.2 152.5 ± 14.2 17.9 18.8
Hispanic 13,067 (28) 4.16 ± 2.03 157.6 ± 13.9 160.6 ± 13.4 9.6 7.5
Non-Hispanic white 4,081 (9) 3.72 ± 2.01 164.6 ± 15.9 167.2 ± 15.8 6.2 6.3
Mother’s education       
Some high school 19,233 (41) 5.09 ± 2.22 152.0 ± 13.9 154.3 ± 13.4 18.5 18.2
High school graduate 16,101 (34) 4.86 ± 2.23 154.4 ± 14.2 156.3 ± 13.8 14.4 14.5
Some college 8,554 (18) 4.49 ± 2.14 158.1 ± 14.6 159.6 ± 14.0 10.1 9.8
College graduate 2,274 (5) 3.88 ± 1.94 164.7 ± 15.4 166.5 ± 15.0 4.9 4.9
Post college 1,006 (2) 3.77 ± 1.92 169.2 ± 15.9 171.1 ± 15.6 3.6 2.8
Low-income       
Yes 41,289 (88) 4.93 ± 2.22 153.6 ± 14.1 155.6 ± 13.5 15.7 15.5
No 5,879 (12) 3.98 ± 2.02 164.0 ± 16.3 165.9 ± 15.9 7.0 7.0
Very low birthweight/early preterm       
Yes 1,955 (4) 5.12 ± 2.25 151.7 ± 14.3 152.8 ± 13.6 20.0 21.5
No 45,213 (96) 4.80 ± 2.21 155.1 ± 14.8 157.1 ± 14.2 14.4 14.2
  1. Cohort includes 47,168 Children with B-Pbs <10 μg/dL Summary statistics, including proportions, were calculated among those with non-missing data for that characteristic.
  2. Reading and Math test scores are normally distributed as reported by the Illinois Standard Achievement Test (ISAT).
  3. Note: Differences in mean blood lead concentrations, reading and math scores were found to be statistically significant (p < 0.0001) for all characteristics using standard t-test and ANOVA methods; Differences in proportions for reading and math failure were statistically significant (p < 0.0001) for all characteristics using chi-square tests.