Integrated Exposure Uptake Biokinetic Research Articles

IEUBK Modeling of Children's Blood Lead Levels in Homes Served by Private Domestic Wells in Three Illinois Counties.

Lead is known to impair neurocognitive development in children. Drinking water is routinely monitored for lead content in municipal systems, but private well owners are not required to test for lead. The lack of testing poses a risk of lead exposure and resulting health effects to rural children. In three Illinois counties, we conducted a cross-sectional study (n = 151 homes) examining water lead levels (WLLs), water consumption, and water treatment status to assess risk of lead exposure among residents using private water wells. Since blood lead levels (BLLs) were not available, EPA's Integrated Exposure Uptake Biokinetic (IEUBK) modeling was used to estimate the incremental contribution of WLL to BLL, holding all other sources of lead at their default values. Nearly half (48.3%) of stagnant water samples contained measurable lead ranging from 0.79 to 76.2 µg/L (median= 0.537 µg/L). IEUBK modeling showed BLLs rose from 0.3 to 0.4 µg/dL when WLLs rose from 0.54 µg/L (the tenth percentile) to 4.88 µg/L (the 90th percentile). Based on IEUBK modeling, 18% of children with a WLL at the 10th percentile would have a BLL above 3.5 µg/dL compared to 27.4% of those with a WLL at the 90th percentile. These findings suggest that the consumption of unfiltered well water likely results in increased blood lead levels in children.

Reduction in water consumption in premise plumbing systems: Impacts on lead concentration under different water qualities

Water conservation measures are increasing in response to regulatory requirements addressing the need for lower environmental footprint and in response to water shortages. In households with lead service lines (LSLs), lowering consumption can adversely impact lead release as it will increase stagnation. Using a lead dissolution model and data from extensive pilot studies on excavated LSLs, the impact of adaptation to different water conservation strategies on dissolved lead contamination at the kitchen tap is assessed under three water qualities and three LSL lengths (3, 14 and 30 m) using hydraulic and water quality modelling. Consumers' behavioural variability is also assessed based on integration of EPANET and results of the stochastic water demand model SIMDEUM. Demand reduction increased the dissolved lead concentrations (Pbdiss) at the end of the LSL with mean values ranging from 28.4 to 63.3 μg/L (without corrosion control) and from 4.6 to 9.9 μg/L with corrosion control (addition of orthophosphate and pH adjustment). Adding orthophosphate (1 mg P/L) to the water reduces the mean Pbdiss values at the kitchen tap from 7.1 μg/L to 1.2 μg/L for a high water demand scenario and from 31.2 to 4.9 μg/L for a low water demand scenario. Finally, the Integrated Exposure Uptake Biokinetic (IEUBK) model is used to predict the potential blood lead levels (BLLs) for children aged 0–84 months. Results showed that the orthophosphate addition of only 1 mg P/L can significantly decrease the proportion of children with a BLL >5 μg/dL, from 82 % to 17 %, under the most extreme water conservation scenario studied, using the 90th percentile of Pbdiss concentrations during usage at kitchen tap. Wide variations of Pbdiss concentrations at the kitchen tap were calculated at times of use over a week (up to 155 μg/L in lower demand scenarios, without corrosion control) showing evident limitations of single random daytime sampling.

Evaluation of the integrated exposure uptake biokinetic (IEUBK) model for lead in children.

The Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK model) was developed by the U.S. Environmental Protection Agency to support assessments of health risks to children from exposures to lead (Pb). This study evaluated performance of IEUBK model (v2.0) as it would be typically applied at Superfund sites to predict blood Pb levels (BLLs) in populations of children. The model was evaluated by comparing model predictions of BLLs to 1144 observed BLLs in a population of children at the Bunker Hill Superfund Site for which there were paired estimates of environmental Pb concentrations. Predicted population geometric mean (GM) BLLs (GM: 3.4 µg/dL, 95% CI: 3.3, 3.5) were within 0.3 µg/dL of observed (GM: 3.6 µg/dL, 95% CI: 3.5, 3.8). The model predicted the observed age trend in GM BLLs and explained ~90% of the variance in the observed age-stratified GM BLLs. The mean predicted probability of exceeding 5 µg/dL (P5) was 27% (95% CI: 24, 29) and observed P5 was 32% (95% CI: 29, 35), a difference of 5%. Differences between geographic area stratified mean P5 (predicted minus observed) ranged from -11 to 14% (mean difference: 2.3%). Although the more general applicability of these findings to other populations remains to be determined in future studies, our results support applications of the IEUBK model (v2.0) for informing risk-based decisions regarding remediation of soils and mitigation of exposures at Superfund sites where the majority of the exposure unit GM BLLs are expected to be ≤5 µg/dL and where it is desired to limit the predicted probability of exceeding 5 µg/dL to <5%.

Legacy sources to new exposures. A preliminary lead risk assessment to children in the Falun mining area

BACKGROUND AND AIM: Like many of Sweden’s metropolitan areas, the city of Falun faces a shortage of affordable housing. The city’s proximity to a historic copper mine presents unique challenges for the growing high-density service and industrial area. Concerns about the feasibility and risks associated with building new housing on land contaminated by the legacy of mining and metal industries motivate a new risk assessment using current reference values for lead. The aim of this project is to undertake a preliminary environmental health-based risk assessment on the lead levels surrounding the mining area, based on previous samples (dust, soil, biomarkers). METHODS: We use environmental samples and research done in Falun from 1986 to 1998 to predict blood lead levels (BLL) today by employing the Integrated Exposure Uptake Biokinetic (IEUBK) software. We further compare calculated to measured BLL from 1993 and to current threshold values from Environmental Protection Agency (EPA) and the Scientific Committee on Health and Environmental Risks (SCHER). RESULTS:The average measured BLL for children 4 years is 3.7 µg/dL and 4 years is 2.8 µg/dL. IEUBK BLL estimates are 1.2-1.4 µg/dL and 0.9-1.1 µg/dL, respectively. Both averages are below the 5 µg/dL threshold used by EPA, and higher or equal than the 1.2 µg/dL associated with the 0,5 µg/dL bodyweight/day tolerable daily intake. CONCLUSIONS:Based on measured and calculated BLL, the exposure exceeds currently acceptable safe levels. However, samples were taken before the ban on leaded gasoline in Sweden in 1994, but also around active mining and smelting. Furthermore, the lead from mining operations in Falun has low bioavailability 0.5%-2%. The lead in the respirable fraction is more associated with smelting operations and leaded gasoline, which have not existed for almost 30 years. Together, these factors result in a possible overestimation of the current lead exposure to children in Falun. KEYWORDS: Built environment, Heavy metals, Exposure assessment-biomarkers of exposure, Risk assessment, Children's environmental health

Issues and Challenges in the Application of the IEUBK Model in the Health Risk Assessment of Lead: A Case Study from Blantyre Malawi.

The risk assessment of lead (Pb) requires the use of biokinetic models to translate measured concentrations of Pb in food and environmental media into blood lead (BPb). The aim of this study was to assess the applicability of the Integrated Exposure Uptake Biokinetic (IEUBK) model in the health risk assessment of Pb among children in Blantyre. Children (152) aged 1–6 years were recruited into this cross-sectional study, and foods, house dust, playground soil, water, and venous blood (1 mL) were collected and analyzed for Pb. A seven-day food frequency questionnaire (FFQ) was used to collect food consumption data. The concentrations of Pb ranged from 0.01 to 3.3 mg/kg in food, 2.3 to 265 mg/kg and 1.5 to 482 mg/kg in house dust and playground soil, respectively, as well as 2.0 µg/dL to 50.4 µg/dL and 6.8 to 39.2 µg/dL for measured and predicted BPb, respectively. Various statistical tests indicated less than satisfactory agreement between measured and predicted BPb values. Despite the lack of reliable food consumption data and other limitations, both the predicted and measured BPb values indicate that children in Blantyre are exposed to high levels of Pb, largely through food and soil as a minor source.

Children and adults are exposed to dual risks from ingestion of water and inhalation of ultrasonic humidifier particles from Pb-containing water

Room-sized ultrasonic humidifiers are exposure pathways to aerosolized metals, with dose positively associated with increased concentrations of metals in fill water. This study innovatively quantifies water ingestion along with inhalation doses from humidifiers for 10–1000 μg/L dissolved lead (Pb) in tap water. The subsequent indoor air Pb concentrations, average daily doses, and inhalation deposited respiratory fractions were predicted under four room scenarios for 3-mo, 12-mo, 28-mo, and 6-yr children and adults. Elevated blood Pb levels (BLLs) in children were modeled using USEPA's Integrated Exposure Uptake Biokinetic (IEUBK) model. Indoor air Pb exceeds the USEPA ambient air standard of 0.15 μg/m3 when humidifier fill water contains 33 μg/L Pb in the small room of 33.5 m3 and 0.2 h−1 air exchange rate (AER). For this room, ~40–46% inhaled Pb-containing humidifier particles deposit in children's respiratory tracts; inhaling humidifier particles from ≥500 μg/L Pb water results in >1 μg/dL BLL in 2–7 yr children. For adults, ~23% of particles deposit in the respiratory tract; 8-h inhalation exposure with ≥17 μg/L Pb water exceeds the California EPA reproductive toxicity guideline of 0.5 μg/day. Larger rooms and higher AER decrease Pb inhalation exposure under the same water Pb concentration.

Assessing Children's Lead Exposure in an Active Mining Community Using the Integrated Exposure Uptake Biokinetic Model.

Lead exposure has been shown to be harmful to humans in various settings and there are no safe levels of blood lead in children. At an Alternative Superfund site in Hayden-Winkelman, Arizona, with an active copper smelter and concentrator, lead exceedances in air and soil have been measured in the past 20 years. In this work, the U.S. Environmental Protection Agency's Integrated Exposure Uptake Biokinetic (IEUBK) model was used to estimate Hayden-Winkelman children's (age 6 months-7 years) blood lead levels (BLLs) using site-specific lead concentrations measured in indoor and outdoor air, soil, indoor dust, and drinking water. Values used by a state agency's airborne lead risk forecast program were also evaluated to determine whether their forecasting program is useful in protecting children's public health. Using site-specific values in the model, the results demonstrated that lead ingested via indoor dust was the major contributor to children's BLLs. In addition, the output of the IEUBK model overestimated actual BLLs of children sampled in the community. The IEUBK model was particularly sensitive to high indoor dust levels, and these site-specific measures increased modeled BLL values. This finding is of significance as the IEUBK model is used worldwide in communities with industrial contamination. This study confirmed that the chief contributor to lead exposure in children is household dust. Thus, for lead exposure risk reduction, agencies working at Superfund sites should focus efforts on decontaminating outdoor soil and dust and indoor lead decontamination.

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

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 &gt; 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.

Predicting children's blood lead levels from exposure to school drinking water in Addis Ababa, Ethiopia.

Human beings could be exposed to impacts associated with heavy metals such as lead (Pb) through drinking water. The objective of this study was to evaluate quality of water consumed by kindergarten school children in Addis Ababa city, who are highly susceptible to issues related to heavy metals in water. Through conducting chemical analysis, using microwave plasma atomic emission spectrophotometry (MP-AES), the level of lead (Pb) was measured at 38 selected schools in the city. Drinking water samples were taken from three water supply sub-systems: Akaki, Legedadi, and Gefersa. Results revealed the average Pb concentration in the city was 62.37 μg/L which is significantly higher than the World Health Organization (WHO) recommended threshold value of 10 μg/L. The children's blood lead levels and exposure to Pb were also calculated using the integrated exposure uptake bio-kinetic (IEUBK) model as per USEPA guidelines. Estimated geometric mean blood lead levels (BLLs) for each school ranged from 4.4 to 13.2 μg/dL. On average, the model predicted that 20% of children in the city will have blood lead levels above the WHO recommended 10 μg/dL. The study can be considered as an unprecedented piece of work as it addresses critical issues and methods to mitigate problems caused by high concentration of Pb in water supply distribution infrastructure.

Predicting Blood Lead Levels among Children Living in Households Making Fishing Nets with Lead Weights in Phuket and Phang Nga Provinces

This study aimed to validate the Integrated Exposure Uptake Biokinetic (IEUBK) model, the computed risk assessment tool, by comparing the predicted blood lead levels and the observed one among children aged 1-7 years old in households making fishing nets, and to develop a predictive model based on environmental lead level in Phuket and Phang Nga Provinces, in the South of Thailand. We identified children in households, which made fishing nets and participated in the Office Disease Prevention and Control 11 Blood Lead Levels Surveillance System (BLLSS). We collected blood lead information, surveillance address and samples from the environment such as soil, water and dust. We calculated the predicted value by using IEUBK program and the site-specific model and compared with observed value to calculate Mean Absolute Error (MAE) and Mean Absolute Percent Error (MAPE). Forty children from different households were recruited. Geometric mean observed blood lead level was 7.6 µg/dL. We found 45% of households with excess lead in surface dust, and 19% in water. The MAE and MAPE of IEUBK model revealed a substantial difference between the observed and predicted values. The site-specific model, including soil, dust in the bed and workwear as predictive variables, had more accuracy predictive capacity. However further study of the IEUBK in other scenarios is needed. 

The relevance of particle size distribution and bioaccessibility on human health risk assessment for trace elements measured in indoor dust

Trace metal contaminants in indoor dust pose a significant potential exposure risk to people because of the time spent indoors and the readily ingested and inhaled fine-grained composition of indoor dusts. However, there is limited trace metal data available on the specific interaction of dust particle size fraction and their respective bioaccessibility/bioavailability and its consequent effect on health risk assessment. This study addresses this knowledge gap by examining bioaccessible and bioavailable trace element concentrations (As, Cr, Cu, Mn, Ni, Pb, Zn) in 152 discrete size fractions from 38 indoor vacuum samples from a larger dataset (n = 376) of indoor dust from Sydney, Australia. Arsenic, Cu, Ni, Pb and Zn were most concentrated in the 90–150 μm fraction with Cr and Mn being more concentrated in < 45 μm fraction. Dust particle size fractions < 45 μm, 45–90 μm, 90–150 μm and 150–250 μm were analysed for their individual gastric phase (G-alone) in vitro trace element bioaccessibilities. Lead exposure risk was estimated using the United States Environmental Protection Agency's Integrated Exposure Uptake Biokinetic (IEUBK) children's model. Mean Pb bioaccessibility was 59.6%, 42%, 62% and 62.2% for < 45 μm, 45–90 μm, 90–150 μm, and 150–250 μm, respectively. Mean Pb absolute bioavailability (ABA) was lower at 26.2%, 18.4%, 27.2% and 27.3% for size fractions < 45 μm, 45–90 μm, 90–150 μm, and 150–250 μm, respectively. The predicted blood Pb (PbB) levels for a hypothetical child aged 1 to 3 years for each of the dust particle size fractions was > 5 μg/dL. Lead concentrations measured in the selected dust samples show a potential for adverse health impacts on young children with the greatest risk being from indoor dust sized 90–150 μm.

Objective ranges of soil-to-dust transfer coefficients for lead-impacted sites

Residential yard soil and indoor dust datasets from eight communities near historical mining, smelting, and refining operations were used to quantify soil track-in, an important factor in evaluating indoor exposures to soil metals and to set residential soil cleanup levels. Regression analyses were used to derive slopes that represent mass soil-to-dust transfer coefficients or MSDs. Lead concentration data were available for all datasets. Arsenic data were available for six of the eight datasets. Cadmium and zinc data were available for one dataset, allowing limited comparison of MSDs for lead with other metals. Covariates that could indicate potential indoor sources of metals, such as house age and indoor heating source, were examined by multivariate regression analysis when available (three datasets). Covariates that could affect soil track-in, such as the amount of bare soil in the yard or having pets, were examined by stratified linear regression analysis when available (two datasets). Most of the R-squared values for lead, cadmium and zinc indicate a good to moderate fit (≥0.25), but for arsenic most indicate a poor fit (<0.25). Significant MSDs for models with a good to moderate fit range from 0.14 to 0.47 for lead, and 0.12 to 0.43 for the other metals (arsenic, cadmium, and zinc). The treatment of outliers was a significant methodological factor affecting the slope of the regressions. Substantial variability is expected among soils at residences due to both physical characteristics of each property and the ways in which residents interact with their home. Survey data providing information on various factors affecting soil track-in help to refine MSD estimates. For three of the datasets, covariate data were available that improved model fit by multivariate or stratified regression analysis for lead. When multivariate or stratified regression analyses were performed, the estimated MSD varied as little as <1% to as great as 200% depending on the dataset, but all estimates were below 0.4. Notably, the MSDs were lowest for the three datasets with the highest soil lead concentrations, i.e., those with average soil lead concentrations greater than 300 mg/kg after outlier removal. For five of the six datasets that had both arsenic and lead sampled, arsenic MSDs were much less than the lead MSDs; however, only two of the sites’ arsenic models had significant MSDs and adequate fit. Cadmium and zinc were only included in one dataset, limiting our ability to draw any conclusions from comparison to those MSDs. The results of our study are consistent with prior studies suggesting that MSDs for metals without internal sources are 0.3–0.4, and application of MSDs in that range will provide more reliable exposure estimates than the 0.7 default value used by the United States Environmental Protection Agency in the Integrated Exposure Uptake Biokinetic (IEUBK) Model.

Análise Crítica da Capacidade Preditiva de Dois Modelos de Avaliação do Risco à Saúde Humana pela Exposição ao Pb em Crianças de 0 a 7 Anos de Idade

Analisou-se a capacidade preditiva de dois modelos de avaliação do risco pela exposição ao chumbo (Pb) em crianças de 0 a 7 anos residentes em uma área comprovadamente contaminada por metais. Os modelos utilizados foram o Integrated Exposure Uptake Biokinetic (IEUBK) e o modelo Public Health Assessment Process. Dois cenários de exposição foram simulados, o primeiro considerado padrão e o segundo individualizado. Foram utilizados antecedentes de uma base de dados gerada mediante estudos anteriores realizados na área contendo valores individuais de concentração de Pb no solo superficial, poeira domiciliar e alimentos vegetais cultivados em quintais e consumidos pela população local. Para verificar as estimativas de ambos os modelos, valores de Pb no sangue (Pb-S) obtidos de forma experimental em crianças residentes na área de estudo foram utilizados. Ambos os modelos, após calibração, se aproximaram ao valor médio de Pb-S obtido experimentalmente (4,25 μg.dL-1 ATSDR; 4,17 μg.dL-1 IEUBK e 4,56 μg.dL-1 experimental). Não foram detectadas diferenças estatisticamente significativas, entre os modelos (p=0,393), quando avaliados os valores médios estimados de Pb-S no cenário sem consumo vegetais. Foi possível observar uma associação linear moderada entre os valores individuais de Pb-S previstos pelo modelo da ATSDR e os calculados pelo modelo IEUBK (r=0,60). Ambos os modelos se apresentaram adequados, quando ajustados, para avaliar o risco pela exposição ao Pb em crianças, contudo, o modelo IEUBK apresentou uma maior praticidade relacionada à economia de recursos e tempo para predizer o risco pela exposição ao Pb.

Human exposure and risk associated with trace element concentrations in indoor dust from Australian homes

This study examines residential indoor dust from 224 homes in Sydney, Australia for trace element concentrations measured using portable X-ray Fluorescence (pXRF) and their potential risk of harm. Samples were collected as part of a citizen science program involving public participation via collection and submission of vacuum dust samples for analysis of their As, Cr, Cu, Mn, Ni, Pb and Zn concentrations. The upper 95% confidence level of the mean values for 224 samples (sieved to <250 μm) were 20.2 mg/kg As, 99.8 mg/kg Cr, 298 mg/kg Cu, 247 mg/kg Mn, 56.7 mg/kg Ni, 364 mg/kg Pb and 2437 mg/kg Zn. The spatial patterns and variations of the metals indicate high homogeneity across Sydney, but with noticeably higher Pb values in the older areas of the city. Potential hazard levels were assessed using United States Environmental Protection Agency's (US EPA) carcinogenic, non-carcinogenic and Integrated Exposure Uptake Biokinetic (IEUBK) model human health risk assessment tools for children and adults. US EPA hazard indexes (HI) for Cr and Pb were higher than the safe level of 1.0 for children. HI > 1 suggests potential non-carcinogenic health effects. Carcinogenic risks were estimated for As, Cr and Pb whose carcinogenic slope factors (CSF) were available. Only the risk factor for Cr exceeded the US EPA's carcinogenic threshold (1 × 10−4) for children. Children aged 1–2 years had the highest predicted mean child blood lead (PbB) of 4.6 μg/dL, with 19.2% potentially having PbB exceeding 5 μg/dL and 5.80% exceeding 10 μg/dL. The Cr and Pb levels measured in indoor dust therefore pose potentially significant adverse health risks to children.

Status of lead accumulation in agricultural soils across China (1979–2016)

The first national-scale assessment of lead (Pb) contamination in agricultural soils across China was conducted based on >1900 articles published between 1979 and 2016. Pb concentrations, temporal and spatial variations, and influencing factors were analyzed. Children's blood lead levels (BLLs) were also estimated using the integrated exposure uptake biokinetic (IEUBK) model. Pb concentrations in different areas of China varied greatly, which was closely associated with the distribution of Pb-related industries, especially Pb-zinc mine smelting, non-ferrous polymetallic mine smelting, e-waste recycling, and leaded gasoline consumption. The year 2000 was a significant transition year for Pb concentrations, with a rapid increase pre-2000 and a subsequent slow upward trend. Pb concentrations were found to be strongly associated with indicators of economic and social development including gross domestic product (GDP), population size, and vehicle ownership. Leaded gasoline, coal combustion, and non-ferrous smelting were the main sources of atmospheric Pb during the different periods. Predicted BLLs were higher in South China than those in the north. This study details the overall Pb contamination status of agricultural soils in China, and thus provides insights for policymakers with respect to pollution prevention measures.

Health risk assessment of Pb and Cd in soil, wheat, and barley in Shazand County, central of Iran.

Heavy metal contamination via mining activity is a serious problem around the world. This study was conducted to evaluate the total non-cancer hazard quotient (THQ) and excess lifetime cancer risks of lead (Pb) and cadmium (Cd) to different population groups via soil, wheat and barley ingestion, soil-dermal contact, and inhalation soil particulates around Shahin mine located in Shazand County. Soil and plants were sampled randomly from 60 agricultural fields around Shahin mine. The samples Pb and Cd concentrations were determined using atomic absorption spectroscopy (AAS). The THQ and the excess lifetime cancer risks of Pb and Cd were estimated using the formulas suggested by the U.S. Environmental Protection Agency (USEPA). The Pb non-cancer risk for children (<6years old) was assessed using the integrated exposure uptake bio-kinetic (IEUBK) model. The mean contents of Pb (234.47mgkg-1) and Cd (1.89mgkg-1) in soil samples were higher than the background values. The mean Pb and Cd concentrations in wheat grains were 0.44 and 0.23μgg-1 respectively, which were about 6.5 and 5.8 times higher than that was observed in barley grains, respectively. The THQ of Pb and Cd for all groups were greater than 1. The excess lifetime cancer risks of Pb via wheat and barley consumption for all receptor groups were greater than 1 × 10-6. Crop ingestion and soil inhalation had the greatest and lowest portions to increase the THQ and excess lifetime cancer risks of Pb and Cd in the study region, respectively.

Chemical fractionation of heavy metals in fine particulate matter and their health risk assessment through inhalation exposure pathway.

Samples of PM2.5 were collected from an urban area close to a national highway in Agra, India and sequentially extracted into four different fractions: water soluble (F1), reducible (F2), oxidizable (F3) and residual fraction (F4) for chemical fractionation of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni) and lead (Pb). The metals were analyzed by inductively coupled plasma optical emission spectroscopy in each fraction. The average mass concentration of PM2.5 was 93 ± 24μgm-3.The total concentrations of Cr, Pb, Ni, Co, As and Cd in fine particle were 192 ± 54, 128 ± 25, 108 ± 34, 36 ± 6, 35 ± 5 and 8 ± 2ngm-3, respectively. Results indicated that Cd and Co had the most bioavailability indexes. Risk Assessment Code and contamination factors were calculated to assess the environmental risk. The present study evaluated the potential Pb hazard to young children using the Integrated Exposure Uptake Biokinetic Model. From the model, the probability density of PbB (blood lead level) revealed that at the prevailing atmospheric concentration, 0.302 children are expected to have PbB concentrations exceeding 10μg dL-1 and an estimated IQ (intelligence quotient) loss of 1.8 points. The predicted blood Pb levels belong to Group 3 (PbB < 5μg dL-1). Based on the bioavailable fractions, carcinogenic and non-carcinogenic risks via inhalation exposure were assessed for infants, toddlers, children, males and females. The hazard index for potential toxic metals was 2.50, which was higher than the safe limit (1). However, the combined carcinogenic risk for infants, toddlers, children, males and females was marginally higher than the precautionary criterion (10-6).

Health Risk Assessment and Remediation Suggestion for Lead Contaminated Soil in a Lead-acid Battery Factory of Shandong Province

Lead is one of the heavy metals which are poisonous to human being, and lead-acid battery is a vital sources for lead pollution. With the development of economics and improvement of environmental consciousness of public, the relocation policy for enterprise was proposed and old factories had to move to the suburban area. The site of a demolished lead-acid factory in Shandong province was investigated and the health risk of lead for human being was assessed by Integrated Exposure Uptake Biokinetic (IEUBK) model. 87 soil samples were collected and the detection results of the sampling sites demonstrated that the soil had been polluted seriously, lead content of 62.1% of the soil samples have exceeded the standard level (600 mg/kg), and 11.5% of the samples have exceeded the standard limit for 10 times. Health risk assessment result confirmed that 70% of the soil samples have serious threat to children’s health, and the investigated site needed to be remediated urgently. Solidification/Stabilization technique was recommended to remediate the lead contaminated soil. This study provided a relative integrated procedure to monitor and assess the health risk of lead contaminated soil for human being, which has a vital reference significance to the future investigation for lead contaminated sites.

Estimates of potential childhood lead exposure from contaminated soil using the USEPA IEUBK model in Melbourne, Australia.

Soils in inner city areas internationally and in Australia have been contaminated with lead (Pb) primarily from past emissions of Pb in petrol, deteriorating exterior Pb-based paints and from industry. Children can be exposed to Pb in soil dust through ingestion and inhalation leading to elevated blood lead levels (BLLs). Currently, the contribution of soil Pb to the spatial distribution of children's BLLs is unknown in the Melbourne metropolitan area. In this study, children's potential BLLs were estimated from surface soil (0-2cm) samples collected at 250 locations across the Melbourne metropolitan area using the United States Environmental Protection Agency (USEPA) Integrated Exposure Uptake Biokinetic (IEUBK) model. A dataset of 250 surface soil Pb concentrations indicate that soil Pb concentrations are highly variable but are generally elevated in the central and western portions of the Melbourne metropolitan area. The mean, median and geometric soil Pb concentrations were 193, 110 and 108mg/kg, respectively. Approximately 20 and 4% of the soil samples exceeded the Australian HIL-A residential and HIL-C recreational soil Pb guidelines of 300 and 600 mg/kg, respectively. The IEUBK model predicted a geometric mean BLL of 2.5 ± 2.1µg/dL (range: 1.3-22.5µg/dL) in a hypothetical 24-month-old child with BLLs exceeding 5 and 10µg/dL at 11.6 and 0.8% of the sampling locations, respectively. This study suggests children's exposure to Pb contaminated surface soil could potentially be associated with low-level BLLs in some locations in the Melbourne metropolitan area.

Lead exposure to children from consumption of backyard chicken eggs

Backyard chicken ownership is rapidly increasing in urban areas in the United States, largely as a way to provide eggs for household consumption. Despite elevated levels of environmental lead contamination in many US cities, the role of backyard chicken eggs as a pathway for lead exposure, particularly for children, has received limited scrutiny. To characterize lead exposure from consumption of backyard chicken eggs for children and predict related effects on blood lead level (BLL), we conducted a cross-sectional study of backyard chicken owners in the Greater Boston area (n = 51). We interviewed participants regarding egg consumption by household members and collected backyard eggs (n = 201) and coop soil samples (n = 48) for analysis. Inductively coupled plasma mass spectrometry (ICP-MS) was used to evaluate lead concentration in homogenized eggs and an X-ray fluorescence (XRF) portable device was used to assess soil lead levels in the laboratory. We used the USEPA's Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK) to assess the relative contribution of backyard egg consumption to aggregate BLL in children. Four scenarios were developed in the IEUBK model to address variability in egg consumption rates and egg lead contamination. Lead was detected in egg samples from 98% of the households that provided egg samples. Mean household lead concentration was 0.10 μg/g (SD: 0.18). Egg lead concentrations ranged from below the limit of detection (0.0014 μg/g) to 1.798 μg/g (<1.4–1198 ppb). Egg lead levels were strongly positively correlated with lead concentration in coop soil (r = 0.64; p < 0.001). In modeled scenarios where a child < 7 years frequently ate eggs highly contaminated with lead, BLLs are predicted to increase by 0.9–1.5 μg/dL. In three other scenarios reflecting more moderate egg lead contamination and consumption rates, BLLs were predicted to increase from 0.1 to 0.8 μg/dL. Consumption of backyard chicken eggs can contribute to lead exposure in children. Soil lead remediation prior to chicken ownership may reduce lead exposure from backyard eggs.