Prediction of Children’s Blood Lead Levels from Exposure to Lead in Schools’ Drinking Water—A Case Study in Tennessee, USA

Abstract

Lead (Pb) exposure can delay children’s mental development and cause behavioral disorders and IQ deficits. With children spending a significant portion of their time at schools, it is critical to investigate the lead concentration in schools’ drinking water to prevent children’s exposure. The objectives of this work were to predict students’ geometric mean (GM) blood lead levels (BLLs), the fractions of at-risk students (those with BLLs > 5 μg/dL), and the total number of at-risk students in one Tennessee school district. School drinking water lead concentration data collected in 2019 were input into the Integrated Exposure Uptake Biokinetic (IEUBK) model and the Bowers’ model to predict BLLs for elementary school students and secondary school students, respectively. Sensitivity analyses were conducted for both models. Drinking water concentrations were qualitatively compared with data collected in 2017. Two scenarios were evaluated for each model to provide upper and median estimates. The weighted GM BLL upper and median estimates for elementary school students were 2.35 μg/dL and 0.99 μg/dL, respectively. This equated to an upper estimate of 1300 elementary school students (5.8%) and a median estimate of 140 elementary school students (0.6%) being at risk of elevated BLLs. Similarly, the weighted GM BLL upper and median estimates for secondary school students were 2.99 μg/dL and 1.53 μg/dL, respectively, and equated to an upper estimate of 6900 secondary school students (13.6%) and a median estimate of 300 secondary school students (0.6%) being at risk of elevated BLLs. Drinking water remediation efforts are recommended for schools exhibiting water lead concentrations greater than 15 μg/L. Site-specific soil lead concentration data are recommended since the IEUBK was deemed sensitive to soil lead concentrations. For this reason, soil lead remediation may have a greater impact on lowering children’s BLLs than drinking water lead remediation. Remediation efforts are especially vital at elementary schools to reduce the population’s baseline BLL and thus the BLL projected by Bowers’ model.

Improved Decision Making for Water Lead Testing in U.S. Child Care Facilities Using Machine-Learned Bayesian Networks

“…There is no established method or reference level to define high or low water lead risk building wide. Previous studies have used the average lead level in a building to determine risk, , but average levels could mask the overall risk to children and students in a building from clusters of outlier taps or even single taps. Indeed, extremely high variability from tap to tap should be expected within schools and child care facilities. , The assumption that the average lead level represents actual exposure to children because of equal consumption across all taps within a building, as previously posited, is also not supported by lead exposure assessments.…”

“…There is no established method or reference level to define high or low water lead risk building wide. Previous studies have used the average lead level in a building to determine risk, 11,28 but average levels could mask the overall risk to children and students in a building from clusters of outlier taps or even single taps. Indeed, extremely high variability from tap to tap should be expected within schools 6 and child care facilities.…”

Studying the impacts of non-routine extended schools' closure on heavy metal release into tap water

“…The Integrated Exposure Uptake Biokinetic (IEUBK) and the Bowers models were employed to evaluate the potential risks of consuming prolonged stagnant tap water by elementary and high school students, respectively. 17,35,36 Since no quantitative models depicting the lead uptake into the bloodstream for students at the middle school age level were available, blood lead level extrapolations have been made only for the elementary and high school students. Although the default values for dietary lead intake (2.22 μg per day), water consumption (0.59 L per day for IEUBK and 2.0 L per day for Bowers), and soil ingestion (0.085 g per day for IEUBK and 0.02 g per day for Bowers) were used, site-specific lead concentrations for soil (52 μg g −1 ), household water (8.63 μg L −1 ), and school water (data from experimental samples) were imported into the model.…”

“…As previous authors have suggested, this difference in effects is likely attributed to young children being more susceptible to lead absorption than older populations, given similar environmental conditions. 17,44 However, since both populations were affected, the models indicate that the extended stagnation could potentially have a detrimental effect on all students' health if they drink the water that was stagnant for an extended period. The distribution of increases in at-risk students across all schools is shown in Fig.…”

“…14 This condition is concerning as a multitude of lead sources [e.g., solder, fitting, brass, galvanized iron pipes, and fixtures] might be present in schools that were built before 1986. 8,9,[15][16][17] However, the lead release into tap water is not only limited to the schools built earlier than 1986, several studies reported the elevated Pb release in schools constructed after that. 18 Furthermore, loss of disinfectant residuals due to the extended water stagnation could promote microbial regrowth within the plumbing system.…”