Policy Changes and Child Blood Lead Levels by Age 2 Years for Children Born in Illinois, 2001-2014

Abstract

Objectives. To evaluate how lowering the blood lead level (BLL) intervention threshold affects childhood lead testing policy.Methods. We geocoded 4.19 million Illinois lead testing records (2001-2016) and linked to 2.37 million birth records (2001-2014), data on housing age, industrial emissions, and roads. We used multinomial logistic regression to determine predictors of BLLs of 10 micrograms per deciliter (µg/dL) or greater, 5 to 9 µg/dL, and 4 µg/dL.Results. We found that 2.2% of children had BLLs of 10 µg/dL or greater, 8.9% had BLLs of 5 to 9 µg/dL, and 5.7% had BLLs of 4 µg/dL. Pre-1930 housing was associated with more than 2- to 4-fold increased relative risk of BLLs above all thresholds. Housing built in 1951 to 1978 was associated with increased relative risk of BLLs of 5 to 9 µg/dL (relative risk ratio [RRR] = 1.14; 95% confidence interval [CI] = 1.06, 1.21) but not with increased relative risk of BLLs of 10 µg/dL or greater (RRR = 0.99; 95% CI = 0.84, 1.16). At a given address, previous BLLs of 5 to 9 µg/dL or BLLs of 10 µg/dL or greater were associated with increased risk of BLLs of 5 to 9 µg/dL or BLLs of 10 µg/dL or greater among current occupants by 2.37- (95% CI = 2.20, 2.54) fold and 4.08- (95% CI = 3.69, 4.52) fold, respectively.Conclusions. The relative importance of determinants of above-threshold BLLs changes with decreasing intervention thresholds.Public Health Implications. States may need to update lead screening guidelines when decreasing the intervention threshold.

FIGURE 1—

Map of Illinois Zip Codes Showing (a) Illinois Department of Public Health Risk Designation and (b) Median Housing Age

FIGURE 2—

Relationship Between Housing Construction Decade and Relative Risk Ratio of Above-Threshold Blood Lead Levels Among Children Aged 0 to 2 Years: Illinois, 2001–2014 Note. RRR = relative risk ratio. The reference category is housing built in 2000 or later. Benjamini–Hochberg–corrected P values of between-group χ2 testing for equality of coefficients are indicated with asterisks at the bottom of the graph. *P < .05; **P < .01; ***P < .001.