Interrupted time series analysis of children's blood lead levels: A case study of lead hazard control program in Syracuse, New York.
ABSTRACT: Children's blood lead concentrations have been closely monitored over the last two decades in the United States. The bio-monitoring surveillance data collected in local agencies reflected the local temporal trends of children's blood lead levels (BLLs). However, the analysis and modeling of the long-term time series of BLLs have rarely been reported. We attempted to quantify the long-term trends of children's BLLs in the city of Syracuse, New York and evaluate the impacts of local lead poisoning prevention programs and Lead Hazard Control Program on reducing the children's BLLs. We applied interrupted time series analysis on the monthly time series of BLLs surveillance data and used ARMA (autoregressive and moving average) models to measure the average children's blood lead level shift and detect the seasonal pattern change. Our results showed that there were three intervention stages over the past 20 years to reduce children's BLLs in the city of Syracuse, NY. The average of children's BLLs was significantly decreased after the interventions, declining from 8.77?g/dL to 3.94?g/dL during1992 to 2011. The seasonal variation diminished over the past decade, but more short term influences were in the variation. The lead hazard control treatment intervention proved effective in reducing the children's blood lead levels in Syracuse, NY. Also, the reduction of the seasonal variation of children's BLLs reflected the impacts of the local lead-based paint mitigation program. The replacement of window and door was the major cost of lead house abatement. However, soil lead was not considered a major source of lead hazard in our analysis.
Project description:Children's health problems caused by the electronic waste (e-waste) lead exposure in China remains. To assess children's blood lead levels (BLLs) in Guiyu of China and investigate risk factors of children's elevated BLLs in Guiyu.842 children under 11 years of age from Guiyu and Haojiang were enrolled in this population-based study during 2011-2013. Participants completed a lifestyle and residential environment questionnaire and their physical growth indices were measured, and blood samples taken. Blood samples were tested to assess BLLs. Children's BLLs between the two groups were compared and factors associated with elevated BLLs among Guiyu children were analyzed by group Lasso logistic regression model.Children living in Guiyu had significant higher BLLs (7.06 µg/dL) than the quantity (5.89 µg/dL) of Haojiang children (P<0.05). Subgroup analyses of BLLs exceeding 10 µg/dL showed the proportion (24.80%) of high-level BLLs for Guiyu children was greater than that (12.84%) in Haojiang (P<0.05). Boys had greater BLLs than girls, irrespectively of areas (P<0.05). The number of e-waste piles or recycling workshops around the house (odds ratio, 2.28; 95% confidence interval [CI], 1.37 to 3.87) significantly contributed to the elevated BLLs of children in Guiyu, and girls had less risk (odds ratio, 0.51; 95% CI, 0.31 to 0.83) of e-waste lead exposure than boys.This analysis reinforces the importance of shifting e-waste recycling piles or workshops to non-populated areas as part of a comprehensive response to e-waste lead exposure control in Guiyu. To correct the problem of lead poisoning in children in Guiyu should be a long-term mission.
Project description:Relationships between total soil or bioaccessible lead (Pb), measured using an in vitro bioaccessibility assay, and children's blood lead levels (BLL) were investigated in an urban neighborhood in Philadelphia, PA, with a history of soil Pb contamination. Soil samples from 38 homes were analyzed to determine whether accounting for the bioaccessible Pb fraction improves statistical relationships with children's BLLs. Total soil Pb concentration ranged from 58 to 2821 mg/kg; the bioaccessible Pb concentration ranged from 47 to 2567 mg/kg. Children's BLLs ranged from 0.3 to 9.8 ?g/dL. Hierarchical models were used to compare relationships between total or bioaccessible Pb in soil and children's BLLs. Total soil Pb concentration as the predictor accounted for 23% of the variability in child BLL; bioaccessible soil Pb concentration as the predictor accounted for 26% of BLL variability. A bootstrapping analysis confirmed a significant increase in R2 for the model using bioaccessible soil Pb concentration as the predictor with 99.0% of bootstraps showing a positive increase. Estimated increases of 1.3 ?g/dL and 1.5 ?g/dL in BLL per 1000 mg/kg Pb in soil were observed for this study area using total and bioaccessible Pb concentrations, respectively. Children's age did not contribute significantly to the prediction of BLLs.
Project description:<h4>Background</h4>Drinking water and other sources for lead are the subject of public health concerns around the Flint, Michigan, drinking water and East Chicago, Indiana, lead in soil crises. In 2015, the U.S. Environmental Protection Agency (EPA)'s National Drinking Water Advisory Council (NDWAC) recommended establishment of a "health-based, household action level" for lead in drinking water based on children's exposure.<h4>Objectives</h4>The primary objective was to develop a coupled exposure-dose modeling approach that can be used to determine what drinking water lead concentrations keep children's blood lead levels (BLLs) below specified values, considering exposures from water, soil, dust, food, and air. Related objectives were to evaluate the coupled model estimates using real-world blood lead data, to quantify relative contributions by the various media, and to identify key model inputs.<h4>Methods</h4>A modeling approach using the EPA's Stochastic Human Exposure and Dose Simulation (SHEDS)-Multimedia and Integrated Exposure Uptake and Biokinetic (IEUBK) models was developed using available data. This analysis for the U.S. population of young children probabilistically simulated multimedia exposures and estimated relative contributions of media to BLLs across all population percentiles for several age groups.<h4>Results</h4>Modeled BLLs compared well with nationally representative BLLs (0-23% relative error). Analyses revealed relative importance of soil and dust ingestion exposure pathways and associated Pb intake rates; water ingestion was also a main pathway, especially for infants.<h4>Conclusions</h4>This methodology advances scientific understanding of the relationship between lead concentrations in drinking water and BLLs in children. It can guide national health-based benchmarks for lead and related community public health decisions. https://doi.org/10.1289/EHP1605.
Project description:Although studies have shown that a low socioeconomic status (SES) is associated with high blood lead levels (BLLs) in children, the mechanism underlying this observation is not well known. To determine how SES influences BLLs via environmental factors in Korean children, we conducted a population-based cross-sectional study of 4744 children aged 5?13 years. Questionnaires on sociodemographic information, environmental factors, and food consumption were administered to the children's parents. BLLs in the study subjects were measured.The complete set of hypothesized associations was assessed using regression analysis and structural equation modeling. SES was associated with high BLLs. The total effects of nutritional factors, lead in the air and total length of nearby roads, and agriculture on BLLs were -0.062 (p < 0.001), 0.068 (p = 0.005), and 0.038 (p = 0.035), respectively. The direct effects of playing outdoors and SES on BLLs were 0.113 (p < 0.001) and -0.111 (p < 0.001), respectively. Although playing outdoors had a greater direct effect on BLLs than did SES, the total effect of SES (standardized ? = -0.132, p < 0.001) was greater than that of other sources owing to indirect effects (? = -0.020, p = 0.004). A low SES was a major risk factor for elevated BLLs via environmental factors.
Project description:We described elevated blood lead level (BLL; ? 10 ?g/dL) prevalence among newly arrived refugee children in Massachusetts. We also investigated the incidence of BLL increases and BLLs newly elevated to 20 ?g/dL or higher in the year following initial testing, along with associated factors.We merged data from the Massachusetts Department of Public Health's Refugee and Immigrant Health Program and the Childhood Lead Poisoning Prevention Program on 1148 refugee children younger than 7 years who arrived in Massachusetts from 2000 to 2007.Elevated BLL prevalence was 16% among newly arrived refugee children. The rate ratio for BLL elevation to 20 ?g/dL or higher after arrival was 12.3 (95% confidence interval [CI] = 6.2, 24.5) compared with children in communities the state defines as high-risk for childhood lead exposure. Residence in a census tract with older housing (median year built before 1950) was associated with a higher rate of BLL increases after resettlement (hazard ratio = 1.7; 95% CI = 1.2, 2.3).Refugee children are at high risk of lead exposure before and after resettlement in Massachusetts. A national surveillance system of refugee children's BLLs following resettlement would allow more in-depth analysis.
Project description:BACKGROUND:Heightened blood lead levels (BLL) are associated with cognitive deficiencies and adverse behavioral outcomes. Lead-contaminated house dust is the primary source of exposure in U.S. children, and evidence suggests that even background (low-level) exposure has negative consequences. Identifying sources of background exposure is of great public health significance because of the larger number of children that can be affected. METHODS:Blood lead was assessed in a bi-racial sample of children from Syracuse, NY, aged 9-11, using established biomonitoring methods. The spatial density of vacant properties was modelled from publicly available georeferenced datasets. Further, regression models were used to measure the impact of this spatial density variable on children's BLL. RESULTS:In a sample of 221 children, with a mean BLL of 1.06?µg/dL (SD = 0.68), results showed increases in spatial density of vacant properties predict increases in median blood-PB levels, b?=?0.14 (0.06-0.21), p?<?.001. This association held true even after accounting for demographic covariates, and age of individual housing. Further analysis showed spatial autocorrelation of the residuals changed from a clustered pattern to a random pattern once the spatial density variable was introduced to the model. DISCUSSION:This study is the first to identify a background-lead exposure source using spatial density modelling. As vacant properties deteriorate, lead-contaminated dust likely disperses into the surrounding environment. High-density areas have an accumulation of lead hazards in environmental media, namely soil and dust, putting more children at risk of exposure.
Project description:INTRODUCTION:Several urban neighborhoods in Philadelphia, Pennsylvania, have a history of soil, household lead paint, and potential lead-emitting industry contamination. OBJECTIVES:To (1) describe blood lead levels (BLLs) in target neighborhoods, (2) identify risk factors and sources of lead exposure, (3) describe household environmental lead levels, and (4) compare results with existing data. METHODS:A simple, random, cross-sectional sampling strategy was used to enroll children 8 years or younger living in selected Philadelphia neighborhoods with a history of lead-emitting industry during July 2014. Geometric mean of child BLLs and prevalence of BLLs of 5 ?g/dL or more were calculated. Linear and logistic regression analyses were used to ascertain risk factors for elevated BLLs. RESULTS:Among 104 children tested for blood lead, 13 (12.4%; 95% confidence interval [CI], 7.5-20.2) had BLLs of 5 ?g/dL or more. The geometric mean BLL was 2.0 ?g/dL (95% CI, 1.7-2.3 ?g/dL). Higher geometric mean BLLs were significantly associated with front door entryway dust lead content, residence built prior to 1900, and a child currently or ever receiving Medicaid. Seventy-one percent of households exceeded the screening level for soil, 25% had an elevated front door floor dust lead level, 28% had an elevated child play area floor dust lead level, and 14% had an elevated interior window dust lead level. Children in households with 2 to 3 elevated environmental lead samples were more likely to have BLLs of 5 ?g/dL or more. A spatial relationship between household proximity to historic lead-emitting facilities and child BLL was not identified. CONCLUSION:Entryway floor dust lead levels were strongly associated with blood lead levels in participants. Results underscore the importance to make housing lead safe by addressing all lead hazards in and around the home. Reduction of child lead exposure is crucial, and continued blood lead surveillance, testing, and inspection of homes of children with BLLs of 5 ?g/dL or more to identify and control lead sources are recommended. Pediatric health care providers can be especially vigilant screening Medicaid-eligible/enrolled children and children living in very old housing.
Project description:BACKGROUND:High blood pressure (BP) in childhood is frequently renal in origin and a risk factor for adult hypertension and cardiovascular disease. Shorter gestations are a known risk factor for increased BP in adults and children, due in part to a nephron deficit in children born preterm. As nephrogenesis is incomplete until 36?weeks gestation, prenatal lead exposure occurring during a susceptible period of renal development may contribute to programming for later life renal disease. The relationship between shorter gestation and children's BP has not yet been explored to identify i) critical windows using nonlinear piecewise models or ii) combined with other early life risk factors such as prenatal lead exposure. OBJECTIVES:(1) To evaluate the nonlinear relationship between lower gestational age and childhood BP measured at 4-6?years of age, and (2) to investigate modification by prenatal lead exposure. METHODS:In a prospective longitudinal birth cohort, we assessed 565 children between 4 and 6?years of age (mean: 4.8?years) in the PROGRESS cohort in Mexico City, Mexico. Gestational age at delivery was calculated using maternal report of last menstrual period (LMP) and confirmed with Capurro physical examination at birth. We measured pregnant women's blood lead levels (BLLs) in the second trimester via inductively coupled plasma-mass spectrometry and children's BP using an automated device. We performed both linear and nonlinear piecewise regression analyses to examine associations of gestational age with children's BP adjusting for children's age, sex, height, prenatal exposure to smoke, and maternal socioeconomic status. We stratified to assess modification by prenatal lead exposure, and used a data-adaptive approach to identify a lead cutpoint. RESULTS:Maternal second trimester BLLs ranged from 0.7 to 17.8??g/dL with 112 (20%) women above the CDC guideline level of 5??g/dL. In adjusted linear regression models, a one week reduction in gestational age was associated with a 0.5?mm?Hg (95%CI: 0.2, 0.8) increase in SBP and a 0.4?mm?Hg (95%CI 0.1, 0.6) increase in DBP. Our nonlinear models suggested evidence for different magnitude estimates on either side of an estimated join-point at 35.9?weeks' gestation, but did not reach statistical significance. However, when stratified by prenatal lead exposure, we identified a cutpoint lead level of concern of 2.5??g/dL that suggested an interaction between gestational age and blood lead. Specifically, for BLLs???2.5??g/dL, SBP was 1.6 (95%CI: 0.3, 2.9) mm?Hg higher per each week reduction in gestational age among children born before 37.0?weeks; and among children born after 37.0?weeks, this relationship was attenuated yet remained significant [?: 0.9, 95%CI (0.2, 1.6)]. At BLLs below 2.5??g/dL, there was no appreciable association between lower gestational age and SBP. CONCLUSIONS:Our findings suggest that shorter gestation combined with higher prenatal lead exposure contributes to a higher risk of increased SBP at 4-6?years of age, particularly among infants born <37?weeks gestation. Our results underscore the importance of preventing prenatal lead exposure - even levels as low as 2.5??g/dL - especially among pregnant women at risk for preterm birth. Given that high BP in childhood is a risk factor for adult hypertension and cardiovascular disease later in life, these results may have implications that extend across the life span.
Project description:This study quantitatively assessed the population-wide lead poisoning conditions in Kabwe, Zambia, a town with severe lead pollution. While existing data have reported concerning blood lead levels (BLLs) of residents in pollution hotspots, the data representing the entire population are lacking. Further, selection bias is a concern. Given the lack of compulsory testing schemes, BLLs have been observed from voluntary participants in blood sampling surveys, but such data can represent higher or lower BLLs than the population average because of factors simultaneously affecting participation and BLLs. To illustrate the lead poisoning conditions of the population, we expanded the focus of our surveys and then econometrically estimated the BLLs of individuals representing the population, including those not participating in blood sampling, using background geographic, demographic, and socioeconomic information. The estimated population mean BLL was 11.9 ?g/dL (11.6-12.1, 95% CI), lower than existing data because of our wide focus and correction of selection bias. However, the scale of lead poisoning remained immense and 74.9% of residents had BLLs greater than 5 ?g/dL, the standard reference level for lead poisoning. Our estimates provide a deeper understanding of the problem and a foundation for policy intervention designs.
Project description:Exposure to lead (Pb) affects multiple health outcomes and physiological systems. In adults, even small increases in blood Pb levels have been associated with decreased glomerular filtration rate, increased risk of hypertension and increased incidence of essential tremor. To date, there have been few Pb-exposure assessments using the United States Occupational Health and Safety Administration (OSHA) regulations. The aim of the present study was to assess Pb-exposure in terms of elevated blood lead levels (BLL) and urinary-?-aminolevulinic acid (U-?-ALA) levels of workers exposed to Pb in the lead acid battery industry in Tamil Nadu, India based on Pb exposure regulations set by the American Conference of Governmental Industrial Hygienists (ACGIH) and OSHA. BLLs and U-?-ALA were estimated in 449 male workers exposed to Pb across ten different job categories in a lead acid battery factory. Worker BLLs were estimated using atomic absorption spectrophotometry and U-?-ALA was estimated using spectrophotometry. The Biological Exposure Index of the American Conference of Governmental Industrial Hygienists (BEI-ACGIH) were used to assess Pb exposure. BLLs <30 ?g/dL were found in 63.5% of workers, and 36.5% of workers had BLLs>30 ?g/dL. The present study also assessed Pb exposure using OSHA regulations and found that 83.3% of workers had BLLs <40 ?g/dL and 16.7% of workers had BLLs>40 ?g/dL. Among these workers, 0.7% of workers had BLLs >60 ?g/dL. An excessive excretion of U-?-ALA (20-40 mg/L) was noted in pasting area workers (2.6%) followed by executives (2.2%) and assembly workers (0.9%). Workers in the job categories of pasting and assembly, as well as executives, are at high risk of Pb exposure compared to other job categories. We recommend placing humidifiers on the roof and keeping a water bath closer the to plate cutting area to reduce fugitive Pb dust emissions. We recommended workers with BLLs >60 ?g/dL be removed from jobs involving Pb exposure and return to work only when their BLLs are <40 ?g/dL. Obtained. The study was approved by the ethics committee of the Regional Occupational Health Centre (Southern) Bengaluru, part of the National Institute of Occupational Health of India. The authors declare no competing financial interests.