Dust Lead Levels Research Articles

Standards for levels of lead in soil and dust around the world

Abstract Lead poisoning is a serious environmental health problem in every country in the world. Exposure to lead results in neurocognitive and behavioral changes, has adverse effects on the immune system, causes anemia, hypertension and perturbs other organ systems. The effects of lead poisoning are most critical for children because their bodies are growing and developing, and particularly because agents that reduce cognitive function and attention span as well as promote disruptive behavior will have life-long consequences. Lead exposure, especially to children, is a major health disparity issue. If the next generation starts with reduced cognitive ability, there will be significant barriers for development of skills and country-wide development. While there are many sources of exposure to lead, the commonest source is lead in soil and dust. Since lead is an element, it does not go away and past releases of lead into the environment remain as soil and dust contamination. This is an especially important route of exposure to children because children regularly play in soil and are exposed via hand-to-mouth activity. In addition to indoor sources of lead, contaminated soil is tracked on shoes or feet and blown by air currents into homes, accumulating in household dust which is a major source of exposure for both children and adults. The purpose of this review is to determine standards presumed to be health protective for lead and dust in different countries. We find that many countries have no standards for lead in soil and dust and rely on standards set by the World Health Organization or the US Environmental Protection Agency, and these standards may or may not be enforced. There is considerable variation in standards set by other countries.

Prevalence of elevated blood lead levels and risk factors among children living in Patna, Bihar, India 2020.

Childhood lead exposure remains a key health concern for officials worldwide, contributing some 600,000 new cases of intellectually disabled children annually. Most children affected by high exposure to lead live in low- and middle-income countries. The leaded gasoline phase out in India was completed in 2000. Yet, in 2020, an estimated 275 million children aged 0 to 9 years had blood lead levels (BLLs) ≥ 5 μg/dL known to adversely affect intelligence and behavior. Lead sources reported in India include spices, cookware, paint, traditional medicines and cosmetics, and lead-acid battery recycling and repair. However, their relative contribution has not been characterized. More than 200 lead pollution sites related to battery recycling and repair activities were identified in Bihar and Jharkhand, India. Ninety percent of the recycling sites had soil lead concentrations exceeding the US Environmental Protection Agency's standards. We compared blood and environmental lead levels in two groups of children in Patna, Bihar. Households in proximity to battery recycling operations (Proximal n = 67) versus households distal to these operations (Distal n = 68). The average age of children was 40 months; 46% were female. Overall, the geometric mean (GM) BLL was 11.6 μg/dL. GM BLLs of children in Proximal and Distal households were not significantly different (10.2 μg/dL vs. 13.1 μg/dL respectively; p≤0.07). About 87% children, 56 Proximal and 62 Distal had BLLs ≥5 μg/dl. Lead concentrations in environmental samples were significantly higher in Proximal households (soil mean 9.8 vs. 1.6 μg/ft2; dust mean 52.9 vs. 29.9 μg/ft2 p<0.001; Proximal vs. Distal respectively) whereas concentrations in all spices were higher in Distal households (mean 46.8 vs 134.5 ppm p<0.001; Proximal vs. Distal respectively), and turmeric (mean 59.4 vs. 216.9 ppm Proximal vs. Distal respectively). In multivariate analyses for all children lead in spices and turmeric and number of rooms in the house were significant while for the Proximal group only lead in spices remained in the model. The predictive value of these models was poor. For the Distal group, a model with lead concentration in spices, turmeric and soil and number of rooms in the house was a much better fit. Of the 34 water samples collected, 7 were above the Indian standard of 10 ppb for lead in drinking water (2 in the Proximal area, 5 in the Distal area). Children in Patna, Bihar, India are exposed to multiple sources of lead, with lead levels in house dust and loose, locally sourced spices the most likely to increase blood lead levels. A holistic approach to blood lead testing and source identification and remediation are necessary to prevent lead exposure.

A study protocol to evaluate the impact of a personal and domestic hygiene intervention on lead exposure in a community next to a mine dump

BackgroundLead has been associated with adverse health effects, especially neurocognitive and behavioural effects, in children. Communities living close to mining land are at risk of elevated exposure to lead.MethodsThis paper outlines a before and after intervention study protocol to evaluate the impact of a personal and domestic hygiene intervention on lead exposure in a community located adjacent to a mine dump. In each participating household, parents or guardians will be interviewed using a structured questionnaire to obtain information on socio-demographic characteristics, living conditions, domestic hygiene practices and potential alternative sources of exposure to lead. A registered nurse will collect hand wipe samples from children aged one to five years, for whom parental consent and where possible child assent has been obtained. Environmental dust samples will be collected from the floors and/or windowsills of children’s dwellings for lead content analysis. Soil samples will be collected from yards to determine lead content. An educational intervention will then be applied to the intervention group, including the engagement of households or guardians in an educational discussion on the sources, pathways of exposure, health effects of lead exposure and protective measures, with the aid of a specially designed educational brochure. Data will be analysed for descriptive and inferential statistics using Stata version 16.DiscussionThe study will determine whether the intervention led to a reduction in indoor dust lead levels, and if shown to be effective, will inform the development of an awareness campaign to reduce lead exposure in communities located in close proximity to mine dumps.Trial registrationThe study is retrospectively registered on ClinicalTrials.gov Protocol Registration and Results System with registration number NCT05265572 and first release date of 18th February 2022.

Pollution characteristics, risk assessment, and source apportionment of potentially toxic elements in road dust at two industrial parks in Trinidad and Tobago, West Indies.

Potentially toxic elements can enter the environment through natural and anthropogenic processes, with the latter considered the primary contributor. Road dust samples from two industrial parks on the island of Trinidad were investigated for heavy metal content, and the pollution status, potential health risks, and source apportionment were evaluated. Samples were acid-digested and analysed by flame atomic absorption spectroscopy. The average levels of cadmium, chromium, copper, manganese, nickel, lead, and zinc in road dust at the Frederick Settlement Industrial Park were 1.14 μg/g, 15.13 μg/g, 66.42 μg/g, 768.49 μg/g, 37.95 μg/g, 55.90 μg/g, and 573.04 μg/g, respectively, while average concentrations at the O'Meara Industrial Park were 1.20 μg/g, 16.97 μg/g, 42.72 μg/g, 482.65 μg/g, 21.12 μg/g, 136.77 μg/g, and 358.70 μg/g, respectively. Contamination assessments evaluated both Fredrick Settlement and O'Meara as typically uncontaminated to moderately polluted, with the overall ecological risk deemed low at all locations. Hazard index values at all sampling areas were lower than 1, indicating no potential non-carcinogenic risks to children or adults, while the carcinogenic exposure risks for cadmium, chromium, and nickel were considered low. Principal component analysis and cluster analysis revealed two main sources of contamination for Fredrick Settlement, and three main sources for O'Meara. Based on the groupings obtained, the presence of potentially toxic elements was attributed primarily to specific anthropogenic activities within the industrial parks, with lesser contributions from vehicular-related sources.

Environmental assessment of pediatric Lead exposure in Tehran; a prospective cross-sectional study

BackgroundIngestion and inhalation are common routes of exposure for lead in humans. Developing countries still have unacceptably high rates of lead toxicity, especially in children. Studies on probable risk factors of lead poisoning in Iranian children are insufficient. In this study, we aimed to evaluate possible environmental factors in children with high blood lead concentrations living in Tehran and neighboring cities.MethodsIn a prospective cross-sectional study between March 2018 and March 2019 we followed all children referred from two pediatric gastrointestinal clinics with blood lead level (BLL) > 5 μg/dL in metropolitan Tehran to investigate possible environmental risk factors in their home. Household specimens including scratched wall paint, house floor dust, windowsill dust, tap water, and consumed spice were evaluated using atomic absorption method to detect lead concentrations. Epidemiological and environmental data collected through in-depth interviews with parents/guardians. Industrial areas were defined based on municipality maps on industrial places.ResultsThirty of 56 parents/guardians with BLL > 5 μg/dL agreed to be followed through environmental investigation. The only categorical statistically significant risk factor was a history of lead poisoning in the family and living in an industrial zone. There was a positive correlation between BLL and interior windowsills dust lead level, r = 0.46, p = 0.01. Scratched paint lead level and BLL showed a significant positive correlation, r = 0.50, p = 0.005. House floor dust lead level (median = 77.4, p < 0.001) and interior windowsill dust lead level (median = 291, p = 0.011) were both significantly higher than the environmental protection agency (EPA) standards of 40 μg/ft2, 250 μg/ft2. Interior windowsill dust lead concentrations were significantly higher in industrial areas (p = 0.026).ConclusionChildren’s playing environment should be cleaned more often to reduce dust. Moreover, specific rules may need to be implemented for paint lead concentrations and air pollution, especially in industrial areas.

Childhood maltreatment and lead levels in middle adulthood: A prospective examination of the roles of individual socio-economic and neighborhood characteristics.

BackgroundLead is a common environmental hazard because of its past use as an additive to gasoline and household paint. Some evidence suggests that children with histories of child abuse and neglect are at elevated risk for residence in communities and households with less desirable characteristics and high levels of exposure to environmental hazards and toxins.ObjectivesTo understand whether childhood maltreatment leads to higher levels of household dust lead and blood lead in adulthood and the extent to which characteristics of a person’s physical environment or individual level socio-economic status (SES) (based on unemployment, poverty, and receipt of public assistance) contribute to understanding the relationship.MethodsA large prospective cohort design study in which abused and neglected children (ages 0–11) were matched with non-maltreated children and assessed in adulthood. Objective and subjective neighborhood characteristics were assessed at approximate age 40 and household dust lead (cleaned and less often cleaned) and blood lead levels were measured at age 41. Blood was collected through venipuncture by a registered nurse as part of a medical status exam.ResultsChildhood maltreatment predicted higher levels of dust lead in less often cleaned household places, residence in worse neighborhoods defined by objective (census tract data) and subjective (reports of physical disorder and lack of social cohesion and control), and higher levels of poverty, receiving public assistance, and unemployment. Only objective neighborhood characteristics mediated the relationship between childhood maltreatment and dust lead level in adulthood. There were also significant paths from objective neighborhood disadvantage and individual level SES to higher levels of blood lead.DiscussionThirty years after their childhood experiences, individuals with documented histories of childhood maltreatment are at higher risk for living in environments as adults with elevated lead levels that may impact other aspects of their lives and compromise their health.

Residential dust lead levels and the risk of childhood lead poisoning in United States children.

The United States Environmental Protection Agency (EPA) recently lowered residential floor and windowsill dust lead hazard standards, but maintained previous post-abatement clearance standards. We examined whether the discrepancy in these regulations places children at higher risk of lead poisoning. In 250 children from Cincinnati, Ohio (2004-2008) living in homes built before 1978, we measured residential floor and windowsill dust lead loadings and blood lead concentrations at ages 1 and 2 years. Using linear regression with generalized estimating equations, we estimated covariate-adjusted associations of dust lead levels with blood lead concentrations and risk of lead poisoning. An increase in floor dust lead from 10 (revised dust lead hazard standard) to 40 μg/ft2 (post-abatement clearance standard) was associated with 26% higher (95% confidence interval (CI):15, 38) blood lead concentrations and 2.1 times the risk of blood lead concentrations ≥5 μg/dL (95% CI: 1.44, 3.06). Extrapolating our findings to US children age 1-5 years, we estimated that 6.9% (95% CI: 1.5, 17.2) of cases of blood lead concentrations ≥5 μg/dL are attributable to floor dust lead loadings between 10 and ≤40 μg/ft2. The EPA's residential dust lead regulations place children at increased risk of lead poisoning. We recommend adopting more protective dust lead standards. We determined whether children are at increased risk of lead poisoning with the 2019 EPA residential post-abatement lead clearance standards being higher than dust lead hazard standards. In this observational study, 2019 EPA dust lead clearance standards were associated with increased risk of lead poisoning compared to the revised dust lead hazard standard. Both EPA standards were associated with increased risk of lead poisoning compared to more stringent standards employed in our study. Extrapolating our findings to US children, the 2019 EPA dust lead clearance standards could place up to 36,700 children at risk of lead poisoning.

Assessment of Child Lead Exposure in a Philadelphia Community, 2014.

Several urban neighborhoods in Philadelphia, Pennsylvania, have a history of soil, household lead paint, and potential lead-emitting industry contamination. 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. 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 μg/dL or more were calculated. Linear and logistic regression analyses were used to ascertain risk factors for elevated BLLs. Among 104 children tested for blood lead, 13 (12.4%; 95% confidence interval [CI], 7.5-20.2) had BLLs of 5 μg/dL or more. The geometric mean BLL was 2.0 μg/dL (95% CI, 1.7-2.3 μg/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 μg/dL or more. A spatial relationship between household proximity to historic lead-emitting facilities and child BLL was not identified. 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 μg/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.

Spatial distribution of lead contamination in soil and equipment dust at children's playgrounds in Beijing, China

Lead contamination is widespread across China, posing a serious public health concern. In quantifying child lead exposure, established health risk assessment (HRA) approaches often take into account residential soil lead levels. However, this may not constitute a significant exposure source for children in urban mainland China, where the population mainly dwell in high-rise buildings without back or front yards. In this setting, children's playgrounds may represent a more probable exposure source. The present study analyzed lead levels in settled dust on playground equipment and in surficial soils at 71 playgrounds in Beijing, China. Our results reveal that the average playground dust lead concentration was 80.5 mg/kg, more than twice the average soil lead concentration of 36.2 mg/kg. It was found that there are differences in statistical and spatial distributions for lead in playground dust and soils. Lead levels in equipment dust were largely consistent across Beijing, with elevated levels detected at locations in the main city area, the newly developed Tongzhou District, and the rural counties. Whereas average soil lead concentrations were higher at playgrounds in the main city area than other areas of Beijing. Statistical analysis suggests that the lead content in dust and soil may derive from different natural and anthropogenic sources. Equipment dust lead may be associated with long-distance atmospheric transportation and deposition. Whereas lead in soil is more likely to be associated with local traffic. This study also found that, in certain areas of Beijing, the risk of blood lead levels (BLLs) exceeding safe levels was up to 6 times higher when based on dust exposure than when based on playground soil exposure. The results of this study suggests that HRA undertaken for children in urban mainland China should pay closer attention to children's playgrounds as a lead exposure source, and, in particular, playground equipment dust.

Preeclampsia and blood lead (and other metals) in Lubumbashi, DR Congo

Among parturient women in Lubumbashi, blood lead concentrations [geometric means (25th–75th percentiles)] were higher among 40 women with preeclampsia [6.66 µg/dL (5.16–79.4)] than among 39 control women matched for age and gestation duration [5.08 µg/dL (4.27–6.30)]. Blood lead exceeded 5 µg/dL in 33 (83%) preeclamptic women and 17 (44%) control women [odds ratio 6.1 (95%CI 2.1–17.1)]. In another study, we found high levels of lead in surface dust collected in front of homes in Lubumbashi (36/127 samples exceeding 120 µg lead/g dust). Our findings support the conclusions of a systematic review that increased blood lead level increases the likelihood of preeclampsia. Moreover, our study indicates that, as in other urban areas in Africa, exposure to lead is unacceptably high among pregnant women in Lubumbashi. Preventive measures are needed to protect mothers and children from the serious adverse effects of lead exposure.

Child Exposure to Lead in the Vicinities of Informal Used Lead-Acid Battery Recycling Operations in Nairobi Slums, Kenya.

Background.Child exposure to lead from informal used lead-acid battery (ULAB) recycling operations is a serious environmental health problem, particularly in developing countries.Objectives.We investigated child exposure to lead in the vicinities of ULAB recycling operations in the Dandora, Kariobangi and Mukuru slums in Nairobi between January and August 2015.Methods.Top soil (n = 232) and floor dust (n = 322) samples were collected from dwelling units (n = 120) and preparatory schools (n = 44) and analyzed using an inductively coupled plasma-optical emission spectrometer at the Mines and Geological Department Laboratory in the Ministry of Mining, Nairobi. From the obtained lead levels in soil and house dust, child blood lead levels were subsequently predicted using the Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK), Windows version.Results.Lead loadings in all the floor dust samples from the Dandora, Kariobangi and Mukuru slums exceeded the United States Environmental Protection Agency (USEPA) guidance value for lead on floors with a range of 65.2 – 58,194 μg/ft2. Control floor dust samples recorded lower lead loadings compared to the Dandora, Kariobangi and Mukuru slums. Lead concentration in 70.7% of the soil samples collected from waste dumps, industrial sites, residential areas, playgrounds and preparatory schools in Dandora, Kariobangi and Mukuru exceeded the respective USEPA guidance values for lead in soils. Lead concentration in 100% of control soil samples were below the respective USEPA limits. The IEUBK model predicted that nearly 99.9% of children ≤ 7 years old living near informal ULAB recycling operations in Dandora, Kariobangi and Mukuru were at risk of being lead poisoned, with predicted blood lead levels (BLL) above the Centers for Disease Control (CDC) reference value for blood lead. A total of 99.9% of exposed children living in the Mukuru slums are likely to have BLL above 34 μg/dL.Conclusions.There is a need for coordinated efforts to decrease lead emissions from informal battery recycling in Nairobi slums and to remediate existing soils, particularly around battery workplaces and dumpsites. The BLL of local children should be clinically tested and appropriate intervention measures taken.

Household interventions for preventing domestic lead exposure in children.

Household interventions for preventing domestic lead exposure in children.

Use of a Field Portable X-Ray Fluorescence Analyzer for Environmental Exposure Assessment of a Neighborhood in Cairo, Egypt Adjacent to the Site of a Former Secondary Lead Smelter

The objectives of this study are to demonstrate for the first time the use of a field portable X-Ray Fluorescence Analyzer (XRF) in a multi-media environmental survey and to use the survey results to determine if residual lead from a once-active secondary lead smelter in Cairo, Egypt, still posed a health risk to the residents when comparing results with US EPA standards. Results were analyzed to determine if relationships among the variables indicated that there were residual impacts of the former smelter. Samples collected inside and near a total of 194 dwellings were analyzed. The mean floor dust lead loading was 7.48 μg lead/ft2. Almost 10% of the dwellings had at least one floor dust wipe sample that exceeded the United States Environmental Protection Agency's (USEPA) interior settled dust lead level of 40 μg lead/ft2. The median paint lead level was 0.04 mg lead/cm2. 17% of the dwellings had at least one interior paint sample that exceeded the USEPA standard of 1.0 mg lead/cm2. Mean soil lead concentration in the study area was 458 ppm and 91 ppm outside the study area. Four of nine composite soil samples exceeded the US EPA limit for bare soil in play areas. Lead concentrations in samples collected in locations outside the study area did not exceed the limit. The highest concentration was in the plot closest to the smelter and may represent residual impact from the former smelter. Statistically significant relationships were not detected between interior floor dust lead loading and either interior paint lead loading or exterior dust lead concentration. Thus, no significant exposure from the former smelter was indicated by these analyses. This may have resulted from the time elapsed since the closing of the smelter and/or the relatively low paint lead levels. Further study is needed in other areas of Egypt near former and active lead smelters. Elevated levels of mercury and arsenic detected in soil samples do not appear to be related to the smelter but warrant further study.

An investigation into porch dust lead levels

Lead in porch dust can expose children through direct contact or track-in to the home, but has not been adequately evaluated. At homes undergoing lead hazard control in Rochester, NY, we sampled settled dust lead on exterior porch floors at baseline, immediately post-lead hazard control and one-year post-work (n=79 homes with complete data) via wipe sampling and collected housing, neighborhood and soil data. Baseline GM porch floor dust lead loading (PbPD) was 68µg/ft2, almost four times more than baseline GM interior floor dust lead (18µg/ft2). Immediate post-work PbPD declined 55% after porch floor replacement and 53% after porch floor paint stabilization (p=0.009 and p=0.041, respectively). When no porch floor work was conducted but lead hazard control was conducted elsewhere, immediate post-work PbPD increased 97% (p=0.008). At one-year, GM PbPD continued to decline for porch replacement (77% below baseline) and paint stabilization (72% below baseline), but where no porch floor work was done, GM PbPD was not significantly different than baseline (p<0.001, p=0.028 and p=0.504, respectively). Modeling determined that porch floor replacement had significantly lower one-year PbPD than stabilization when baseline PbPD levels were higher than 148µg/ft2 (the 77th percentile) but not at lower levels. Treatment of porches with lead paint results in substantial declines in PbPD levels. It is of concern that PbPD levels increased significantly at immediate post-work when lead hazard control was not conducted on the porch but was conducted elsewhere. Standards for porch lead dust should be adopted to protect children from inadequate clean-up after lead hazard control.

Source contributions of lead in residential floor dust and within-home variability of dust lead loading

Evidence of the impact of exposure to low levels of lead on children's health is increasing. Residential floor dust is the assumed origin of lead exposure by young children. In this study, we estimate the contribution of different lead sources to household interior floor dust contamination. We also estimate the within-home variability of interior floor dust lead loadings. A multilevel model was developed based on data collected in a French survey in 2008–2009 (484 housing units, 1834 rooms). Missing data were handled by multiple imputation using chained equations. The intra-home correlation between interior floor Log dust lead loadings was approximately 0.6. Dust lead from the landing of an apartment, mostly originating outside the building, was the major contributor to interior floor dust lead. Secondary contributors included the lead-based paint on exterior railings, track-in of the exterior soil of the children's play area into the dwelling, smoking inside the home, demolition of nearby old buildings and sites of pollution in the vicinity. Interior lead-based paint contaminated interior floor dust only in old and non-renovated dwellings. To reduce interior floor dust lead levels in the general population of dwellings, common areas should be maintained, and track-in from the outside should be limited as much as possible.

Human health risk from Pb in urban street dust in northern UK cities

The presence of Pb in the environment can cause significant health problems. These issues are exasperated when the lead is in a more amenable form for potential ingestion. This study investigates the potential human health risk from Pb in urban street dusts. The lead levels in urban street dust in major city centres in northern UK have been compared to levels determined in 35 cities around the world. With a few exceptions, it was noted that the mean Pb levels in this study exceeded those found in other cities worldwide. Samples (n = 15) of urban street dust were collected across five city centres, and specifically in areas in which pedestrians are likely to concentrate, as well as near historical buildings. Typical total lead concentrations across all sampling sites ranged from 306 to 558 mg/kg. The human health risk was assessed using oral bioaccessibility testing of the urban street dust. The mean oral bioaccessibility data, irrespective of site and sample location, were in the range 43 ± 9 %. The total and bioaccessible concentrations of lead were compared to the estimated tolerable daily intake (TDIoral) values based on unintentional soil/dust consumption. It is noted, in all cases, that the maximum estimated lead daily intake exceeded the TDIoral. An alternative approach for assessing the daily intake is proposed based on the actual measured air quality in selected cities on the same day as the sampled urban dust.

Implications of different residential lead standards on children's blood lead levels in France: Predictions based on a national cross-sectional survey

Despite the dramatic reductions in children's blood lead levels (BLLs), there is considerable evidence that low-level lead exposure is associated with intellectual deficits and behavioral problems, without apparent threshold. There are limited data, however, about the contribution of residential sources of lead to contemporary children's blood lead levels. The aim of this study is to calculate the contributions of residential sources of lead to assess the potential impact of setting new standards for lead levels in residential dust, soil and water. We enrolled 484 French children aged from 6 months to 6 years, and collected data on social, housing and individual characteristics. Lead concentrations in blood and environmental samples (water, soils, and dusts) were measured using inductively coupled plasma mass spectrometry. Data were analyzed using a multivariate generalized additive model accounting for the sampling design and the sampling weights. We found that exceedingly low concentrations of lead in dust, soil and water were significant predictors of children's BLLs, after adjustment for potential confounding variables. Lead-contaminated floor dust was the main source of lead in blood. BLLs (GM: 14μg/L) increased by 65%, 13%, 25%, and 5% when lead content in floor dust, loose soil, hard soil and water increased from their 25th percentile to their 95th percentile, respectively. We also observed that the steepest increase in BLLs occurred at the lowest levels of lead-contaminated floor dust, which indicates that lead contamination should be kept as low as possible. Impact of different possible standards on children's BLLs was also tabulated and indicated that unless standards are set low, they will only benefit a small proportion of children who have the highest exposures.

Lead exposure assessment from study near a lead-acid battery factory in China

The production of lead-acid battery in China covered about one-third of the world total output and there are more than 2000 lead-acid battery factories. They may cause the major environment lead pollution. Blood lead levels of several hundreds of residents were over 100μg/L due to the waste discharges from a lead-acid battery factory in Heyuan, Guangdong province. This study aimed to find out the environmental lead sources, the human lead exposure pathways, and the amplitudes from a lead-acid battery factory. The study results showed that lead levels in soil, dust, tree leaves and human blood declined with the distances increased from the production site. Twenty nine of 32 participants had blood lead levels of over 100μg/L with an exceptional high value of 639μg/L for one child. This result suggested that the lead-acid battery production from this factory has caused the elevated lead levels in its neighboring environment and residents. Dust intake was the dominant exposure pathway for humans (over 90%). The lead levels found in adult and toddler (6.19 and 50.1μg/kg/d, respectively) in the polluted area were far higher than the provisional tolerable weekly intake (PTWI) of 25μg/kg body weight (translated into 3.5μg/kg/d), which was established by the joint FAO/WHO Expert Committee. Blood lead levels within the family members were strongly correlated with the house dust lead levels. Our results in this study suggested that further studies in this area should be performed to assess human exposure and relevant human health risks from living close to lead-acid battery factories.

Primary Prevention of Lead Exposure—Blood Lead Results at Age Two Years

Objectives: The Philadelphia Lead Safe Homes (LSH) Study was designed to evaluate whether educational and environmental interventions in the first year of life for families of newborns increased knowledge of lead exposure prevention and were associated with less elevation of blood lead levels (BLLs) for these children, when compared to children receiving standard care. Methods: The current study performed descriptive statistics on the second-year BLL data for both groups and compared these using chi-square tests for proportions and unpaired t-tests for means. Results: A BLL result was found for 159 (50.6%) of the 314 LSH cohort children and 331 (52.7%) of the 628 control children (p = 0.1). Mean and standard deviation for age at draw was 23.8 (3.4) months versus 23.6 (3.1) months (P = 0.6). Geometric mean BLLs were 3.7 versus 3.5 µg/dL (P = 0.4). The percentages of the cohort group with a BLL of ≥20, ≥10 and ≥5 μg/dL, respectively, were 0.6%, 5% and 30%; for the controls 1.2%, 6.6%, and 25%. These percentages were not significantly different between groups. Conclusion: A comparison of geometric mean BLLs and percentages above several BLL cut points drawn at age two years in a group of urban newborns benefitting from study interventions versus a group of similar urban children did not yield statistically significant differences. Both groups had relatively lower lead levels when compared to historical cohort groups, which may reflect a continuing downward trend in BLLs in U.S. children. The interventions did result in benefits to the families such as an increase in parental knowledge about lead exposure prevention and in-home wet cleaning activity, and a decrease in lead dust levels in study homes.

Effect of selenium supplementation on sFlt-1 level in pregnant women in high risk of pre-eclampsia

Among parturient women in Lubumbashi, blood lead concentrations [geometric means (25th–75th percentiles)] were higher among 40 women with preeclampsia [6.66 µg/dL (5.16–79.4)] than among 39 control women matched for age and gestation duration [5.08 µg/dL (4.27–6.30)]. Blood lead exceeded 5 µg/dL in 33 (83%) preeclamptic women and 17 (44%) control women [odds ratio 6.1 (95%CI 2.1–17.1)]. In another study, we found high levels of lead in surface dust collected in front of homes in Lubumbashi (36/127 samples exceeding 120 µg lead/g dust). Our findings support the conclusions of a systematic review that increased blood lead level increases the likelihood of preeclampsia. Moreover, our study indicates that, as in other urban areas in Africa, exposure to lead is unacceptably high among pregnant women in Lubumbashi. Preventive measures are needed to protect mothers and children from the serious adverse effects of lead exposure.