Identification of sources of lead exposure in French children by lead isotope analysis: a cross-sectional study

Identifying Sources of Lead Exposure for Children in the Republic of Georgia, with Lead Isotope Ratios

In the Republic of Georgia, a 2018 national survey estimated that more than 40% of children aged 2-7 years had a blood lead concentration (BLC) of more than 5 µg/dL. The objective of this study was to document the feasibility of employing lead isotope ratios (LIRs) to identify and rank the Pb (lead) exposure sources most relevant to children across Georgia. A cross-sectional survey between November 2019 and February 2020 of 36 children previously identified as having BLCs > 5 µg/dL from seven regions of Georgia involved the collection of blood and 528 environmental samples, a questionnaire on behaviours and potential exposures. The LIRs in blood and environmental samples were analysed in individual children and across the whole group to ascertain clustering. A fitted statistical mixed-effect model to LIR data first found that the blood samples clustered with spices, tea, and paint, then, further isotopically distinct from blood were sand, dust, and soil, and lastly, milk, toys, pens, flour, and water. Analysis of the LIRs provided an indication and ranking of the importance of Pb environmental sources as explanatory factors of BLCs across the group of children. The findings support the deployment of interventions aimed at managing the priority sources of exposure in this population.

Positive outcomes from U.S. lead regulations, continued challenges, and lessons learned for regulating emerging contaminants

Albeit slow and not without its challenges, lead (Pb) emissions and sources in the United States (U.S.) have decreased immensely over the past several decades. Despite the prevalence of childhood Pb poisoning throughout the twentieth century, most U.S. children born in the last two decades are significantly better off than their predecessors in regard to Pb exposure. However, this is not equal across demographic groups and challenges remain. Modern atmospheric emissions of Pb in the U.S. are nearly negligible since the banning of leaded gasoline in vehicles and regulatory controls on Pb smelting plants and refineries. This is evident in the rapid decrease of atmospheric Pb concentrations across the U.S. over the last four decades. One of the most significant remaining contributors to air Pb is aviation gasoline (avgas), which is minor compared to former Pb emissions. However, continual exposure risks to Pb exist in older homes and urban centers, where leaded paint and/or historically contaminated soils + dusts can still harm children. Thus, while effective in eliminating nearly all primary sources of Pb in the environment, the slow rate of U.S. Pb regulation has led to legacy sources of Pb in the environment. More proactive planning, communication, and research of commonly used emerging contaminants of concern that can persist in the environment long after their initial use (i.e., PFAS) should be prioritized so that the same mistakes are not made again.

Associations with Blood Lead and Urinary Cadmium Concentrations in Relation to Mortality in the US Population: A Causal Survival Analysis with G-Computation

Using the parametric g-formula, we estimated the 27-year risk of all-cause and specific causes of mortality under different potential interventions for blood lead (BLLs) and urinary cadmium (UCd) levels. We used data on 14,311 adults aged ≥20 years enrolled in the NHANES-III between 1988 and 1994 and followed up through 31 Dec 31 2015. Time and cause of death were determined from the National Death Index records. We used the parametric g-formula with pooled logistic regression models to estimate the relative and absolute risk of all-cause, cardiovascular, and cancer mortality under different potential threshold interventions for BLLs and UCd concentrations. Median follow-up was 22.5 years. A total of 5167 (36%) participants died by the end of the study, including 1550 from cardiovascular diseases and 1135 from cancer. Increases in BLLs and creatinine-corrected UCd levels from the 5th to the 95th percentiles were associated with risk differences of 4.17% (1.54 to 8.77) and 6.22% (4.51 to 12.00) for all-cause mortality, 1.52% (0.09 to 3.74) and 1.06% (-0.57 to 3.50) for cardiovascular disease mortality, and 1.32% (-0.09 to 3.67) and 0.64% (-0.98 to 2.80) for cancer mortality, respectively. Interventions to reduce historical exposures to lead and cadmium may have prevented premature deaths, especially from cardiovascular disease.

The Use of Pb Isotope Ratios to Determine Environmental Sources of High Blood Pb Concentrations in Children: A Feasibility Study in Georgia

The incidence of lead (Pb) poisoning in children in Georgia has been identified as a major health concern, with a recent national survey identifying that 41% of children aged 2-7 years had blood lead concentrations (BLCs) greater than the blood lead reference value (BLRV) of ≥5 µg dL^-1. This study collected samples of blood, spices, paint, soil, dust, flour, tea, toys, milk, and water from 36 households in Georgia where a child had previously been identified as having a BLC > BLRV. The Pb concentrations of these samples were determined and compared to Georgian reference values. Samples from 3 households were analysed for their Pb isotope composition. The Pb isotope composition of the environmental and blood samples were compared to identify the most likely source(s) of Pb exposure. This approach identified that some spice and dust samples were the likely sources of Pb in the blood in these cases. Importantly, some soil, paint, and dust sources with high Pb concentrations could be discounted as contributing to blood Pb based on their distinct isotope composition. The data presented demonstrate the significant contribution that Pb surveillance and Pb isotope ratio analyses can make to managing Pb exposure in regions where high BLCs are identified.

Potential benefits of joint hypothetical interventions on diet, lead, and cadmium on mortality in US adults

BACKGROUND

Previous studies reported associations between high blood lead levels (BLLs) and urinary cadmium (UCd) concentrations and all-cause and cause-specific mortality. It is hypothesized that these associations are mediated by inflammation; therefore, adherence to an anti-inflammatory diet may mitigate these effects. We sought to estimate the potential effects of joint hypothetical interventions on metals levels and adherence to an anti-inflammatory diet or fruits and vegetables (FV) intake on the expected mortality distributions.

METHODS

We used data on 14,311 adults aged ≥ 20 years enrolled in the NHANES-III between 1988 and 1994 and followed up through Dec 31, 2015. We estimated daily FV servings and adherence to the dietary inflammatory index at baseline using 24-hour dietary recalls. Mortality was determined from the National Death Index records. We used the parametric g-formula with pooled logistic regression models to estimate the absolute risk of all-cause, cardiovascular, and cancer mortality under different hypothetical interventions compared to the natural course (no intervention).

RESULTS

Overall, we observed a decreased mortality risk when intervening to lower metals levels or increasing adherence to an anti-inflammatory diet or the daily FV servings. The joint intervention to lower BLLs and UCd and increase the adherence to the anti-inflammatory diet had the strongest impact on cancer mortality risk (risk difference [RD] = -1.50% (-2.52% to -0.62%)) compared to the joint intervention only on metals levels RD= -0.97% (-1.89 to 0.70). The same pattern of associations was observed for the joint intervention to lower both metals and increased daily FV servings and cardiovascular diseases mortality risk.

CONCLUSION

Higher diet quality may constitute a complementary approach to the interventions to reduce exposures to cadmium and lead to further minimize their effects on mortality. A paradigm shift is required from a pollutant-focused only to a combination with a human-focused approach for primary prevention against these metals.

Children's exposure to environmental lead: A review of potential sources, blood levels, and methods used to reduce exposure

Lead has been used for thousands of years in different anthropogenic activities thanks to its unique properties that allow for many applications such as the manufacturing of drinking water pipes and its use as additives to gasoline and paint. However, knowledge of the adverse impacts of lead on human health has led to its banning from several of its applications, with the main goal of reducing environmental pollution and protecting human health. Human exposure to lead has been linked to different sources of contamination, resulting in high blood lead levels (BLLs) and adverse health implications, primarily in exposed children. Here, we present a summary of a literature review on potential lead sources affecting blood levels and on the different approaches used to reduce human exposure. The findings show a combination of different research approaches, which include the use of inspectors to identify problematic areas in homes, collection and analysis of environmental samples, different lead detection methods (e.g. smart phone applications to identify the presence of lead and mass spectrometry techniques). Although not always the most effective way to predict BLLs in children, linear and non-linear regression models have been used to link BLLs and environmental lead. However, multiple regressions and complex modelling systems would be ideal, especially when seeking results in support of decision-making processes. Overall, lead remains a pollutant of concern and many children are still exposed to it through environmental and drinking water sources. To reduce exposure to lead through source apportionment methods, recent technological advances using high-precision lead stable isotope ratios measured on multi-collector induced coupled plasma mass spectrometry (MC-ICP-MS) instruments have created a new direction for identifying and then eliminating prevalent lead sources associated with high BLLs.

Reduction in Blood Lead Concentration in Children across the Republic of Georgia following Interventions to Address Widespread Exceedance of Reference Value in 2019

In recent years, reports of lead contamination have dramatically increased in Georgia. Given concerns about the exposure of children to lead (Pb), the National Multiple Indicator Cluster Survey (MICS-2018) included a blood sampling component. The results showed that 41% of the children that participated had blood Pb levels (BLL) ≥ 5 µg/dL and that BLL in children living in Western Georgia were higher than those in Eastern regions. In response to these findings, NCDC implemented written and verbal advice to the families of children who participated in the MICS-2018 on how to reduce Pb exposure. From August 2019 onwards, the state program of clinical follow-up was implemented. The design of this study was a longitudinal study. The intervention of interest was the public health advice and medical follow-up, and the outcome was defined as the difference in BLL between the MICS-2018 survey and the state program follow-up. We observed a significant overall reduction in median BLL between MICS-2018 and state program follow-up in both August 2019 and the latest results (until December 2019). However, we did not observe any significant further reduction between August and the most recent BLL results. In the Georgian setting, written and verbal communication targeting individual households, alongside home visits to the most exposed, effectively reduced BLL in children.

The Isotopic Signature of Lead Emanations during the Fire at Notre Dame Cathedral in Paris, France

When Notre Dame de Paris cathedral caught fire on 15 April 2019, lead particles were deposited in its surroundings. Our objective was to determine whether the lead plume had a homogeneous isotopic signature (i.e., a set of homogenous isotopic ratios), and whether, if so, this was different from common sources. In January 2020, dust samples were collected from six areas inside the cathedral, downwind of the fire, as well as from eight roof debris fragments. These samples were mineralized and analyzed using ICP-MS. Their isotopic ratios (207Pb/206Pb and 206Pb/204Pb) were determined and then compared both to each other and to previous published ratios measured in home dusts and blood samples collected in France. The isotopic ratios of dust samples collected inside the cathedral were compatible with each other and with the roof fragments. These isotopic ratios are common and differ neither from those of many other dusts collected in France during the period 2008–2009, nor from those of blood samples collected from children in France during the same period. Moreover, the fire’s isotopic signature is close to the overall signature for Paris. Indeed, it would be difficult to attribute the fire at the cathedral to either lead poisoning or environmental contamination.

Source Identification Analysis of Lead in the Blood of Japanese Children by Stable Isotope Analysis

Considering the negative effect of lead (Pb) on children's neurodevelopment, Pb exposure should be minimized to the lowest extent possible, though the blood Pb (BPb) concentrations in Japanese children are among the lowest in the world. To identify the sources of Pb in blood, isotope ratios (IRs: 207Pb/206Pb and 208Pb/206Pb) of Pb (PbIR) in whole blood from eight Japanese children were measured by multi-collector ICP mass spectrometry. Further, samples of house dust, soil, duplicate diet, and tobacco, collected from home environments, were also measured and were compared with PbIR of blood case by case. The relative contribution of Pb in the home environment to BPb were estimated by linear programming (finding an optimal solution which satisfy the combination of IRs and intakes from various sources) when appropriate. Source apportionment for three children could be estimated, and contributions of diet, soil, and house dust were 19-34%, 0-55%, and 20-76%, respectively. PbIR for the remaining five children also suggested that non-dietary sources also contributed to Pb exposure, though quantitative contributions could not be estimated. Non-dietary sources such as soil, house dust, and passive tobacco smoke are also important contributors to Pb exposure for Japanese children based on PbIR results.

Blood lead level (BLL), δ-aminolevulinic acid dehydratase activity (ALAD), hemoglobin (Hb) and hematocrit (hct) in primary school-children and adult residents living in smelter rural areas in Kosovo

The objective of this study was to investigate the effects of chronic environmental lead (Pb) exposure in blood lead level (BLL), δ-aminolevulinic acid dehydratase (ALAD) activity, hemoglobin (Hb) amount and hematocrit (Hct) value in primary schoolchildren and adults. Blood was obtained for BLL, ALAD, Hb and Hct measurements in 23 primary schoolchildren (girls and boys) and 117 adult residents (women and men) living in three villages (Kelmend, Boletin and Zhazhë) defined by concentric circles 2, 3 and 5 km in radius drawn around from the smelter-refinery complex "Trepça"in Zveçan and in Koliq village 40 km away. As expected, BLLs were substantially higher in the schoolchildren from smelter area compared with control (11 ± 4.2 µg/L and 6.9 ± 1.6 µg/L respectively) and in adult residents from Kelmend, Boletin and Zhazhë (24 ± 11.8, 12 ± 4.5, 11 ± 5.4 and 8.0 ± 2.8 µg/L respectively). Blood ALAD activity of children in Zhazhë is 16% inhibited compared to control and blood ALAD activity in adults in villages from smelter area is 32, 3%, 48, 4% and 17, 8% inhibited compared to control. There is no difference of Hb and Hct values in schoolchildren from Zhazhë and in adult residents from Kelmend and Zhazhë compared with control. Results of this study provide evidence of moderate inverse correlation between BLL and ALAD activity in both examined cohorts from smelter area. The inhibition of ALAD activity in primary schoolchildren and adults occurred at blood lead levels < 24 µg/L; consequently it can cause an increase of δ- Aminolevulinic acid.

Sources of Blood Lead Exposure in Rural Bangladesh

Lead (Pb) exposure is a major public health problem worldwide. Although high levels of Pb in blood in Bangladesh have been documented, the dominant Pb sources contributing to human exposure in rural Bangladesh have not been determined. Here, we first obtained blood from pregnant women from three rural Bangladeshi districts who were previously assessed by a case-control and sampling study, and we then conducted semistructured in-depth interviews to understand Pb exposure behavior and finally collected samples of the suspected Pb sources. We measured the Pb isotopic composition of both potential Pb sources and 45 blood samples in order to understand which of three sources predominate: (1) food from Pb-soldered cans, (2) turmeric, or (3) geophagous materials (clay, soil, or ash). The Pb isotope ratios of the three sources are distinct (p = 0.0001) and blood isotope ratios are most similar to turmeric. Elevated lead and chromium (Cr) concentrations in turmeric and a yellow pigment used in turmeric processing are consistent with reported consumption behavior that indicated turmeric as a primary contributor to blood Pb. The Pb isotopic composition analyses combined with a case-control and sampling approach provides evidence that turmeric adulterated with the yellow Pb-bearing pigment is the main Pb exposure source in these districts and illustrates the need to assess drivers and practices of turmeric adulteration, as well as the prevalence of adulteration across South Asia.

Prenatal exposure to lead in France: Cord-blood levels and associated factors: Results from the perinatal component of the French Longitudinal Study since Childhood (Elfe)

BACKGROUND

As a result of the ban on lead in gasoline on 2nd January 2000, the French population's exposure to lead has decreased in recent years. However, because of the acknowledged harmful cognitive effects of lead even at low levels, lead exposure remains a major public health issue. In France, few biomonitoring data are available for exposure to lead in pregnant women and newborn. The purpose of the perinatal component of the French human biomonitoring (HBM) program was to describe levels of various biomarkers of exposure to several environmental pollutants, including lead, among mother-baby pairs. In this paper, we aimed to describe the distribution of cord blood lead levels (CBLL) in French mother-baby pairs, and to estimate the contribution of the main lead exposure risk factors to these levels.

METHOD

A total of 1968 mother-baby pairs selected from the participants of the perinatal component of the French HBM program were included in the study on lead. Lead levels were analyzed in cord blood collected at child delivery by inductively coupled plasma-mass spectrometry (ICP-MS). The data collected included biological sample, socio-demographic characteristics, environmental and occupational exposure, and information on dietary factors.

RESULTS

CBLL were quantified for 99.5% of the sample. The CBLL geometric mean was 8.30 μg/l (95% CI [7.94-8.68]) with a 95th percentile of 24.3 μg/l (95% CI [20.7-27.1]). Factors significantly associated with CBLL were tap water consumption, alcohol consumption, shellfish consumption, vegetable consumption, bread consumption, smoking, and the mother being born in countries where lead is often used.

CONCLUSION

This study provides the first reference value for CBLL in a random sample of mother-baby pairs not particularly exposed to high levels of lead (24.3 μg/l). A substantial decrease in CBLL over time was observed, which confirms the decrease of exposure to lead among the general population. CBLL observed in this French study were in the range of those found in recent surveys conducted in other countries.

Lead Speciation and In Vitro Bioaccessibility of Compost-Amended Urban Garden Soils

In situ soil amendments can modify the Pb bioavailability by changing soil Pb speciation. Urban soils from three vegetable gardens containing different total Pb concentrations were used. The study evaluated how compost amendment and aging of soil-compost mixture in situ affected the following: (i) soil Pb speciation in the field and (ii) change of soil Pb speciation during an in vitro bioaccessibility extraction mimicking gastric phase dissolution at pH 2.5. X-ray absorption fine structure spectroscopy was used to determine Pb speciation in amended and nonamended soils and residues left after in vitro bioaccessibility extraction of those soils. Compost amendment and aging of compost in the field had a negligible effect on Pb bioaccessibility in the soils. Major Pb species in the soils were Pb sorbed to Fe oxy(hydr)oxide (Pb-Fh) and to soil organic C (Pb-Org). The fraction of Pb-Org was increased as soil-compost mixture aged in the field. During the in vitro extraction, the fraction of Pb-Fh was decreased, the fraction of Pb-Org was increased, and hydroxypyromorphite was formed in both amended and nonamended soils. Freshly incorporated compost enhanced the dissolution of Pb-Fh during the extraction. As soil-compost mixture aged in the field, the dissolution of Pb-Fh was low, demonstrating more stability of the Pb-Fh during the extraction. Compost amendment showed potential to contribute to reduced bioaccessibility of Pb as compost aged in the soil by increasing Pb-Org fraction in the field and stability of Pb-Fh during the in vitro bioaccessibility extraction.

Probabilistic modeling of aggregate lead exposure in children of urban China using an adapted IEUBK model

Lead, a ubiquitous pollutant throughout the environment, is confirmed to be neurotoxic for children by pulmonary and oral routes. As preschool children in China continue to be exposed to lead, we analyzed the available biomonitoring data for preschool children in urban China collected in the period 2004-2014 through a literature review. To identify apportionment of lead exposure sources for urban children in China, we modified the IEUBK model with a Monte Carlo module to assess the uncertainty and variability of the model output based on limited available exposure data and compared the simulated blood lead levels with the observed ones obtained through literature review. Although children's blood lead levels in urban China decreased statistically over time for the included studies, changes in blood lead levels in three economic zones and seven age groups except for two age-specific groups were no longer significant. The GM-predicted BLLs and the GM-observed BLLs agreed within 1μg/dL for all fourteen cities. The 95% CIs for the predicted GMs and the observed distribution (GM±GSD) overlapped substantially. These results demonstrated the plausibility of blood lead prediction provided by the adapted IEUBK model. Lead exposure estimates for diet, soil/dust, air, and drinking water were 12.01±6.27μg/day, 2.69±0.89μg/day, 0.20±0.15μg/day, and 0.029±0.012μg/day, respectively. These findings showed that the reduction of lead concentrations in grains and vegetables would be beneficial to limit the risk of dietary lead exposure for a large proportion of preschool children in urban China.

Tracing lead contamination in foods in the city of Kolkata, India

Lead isotopic ratios (LIR) of eight common food items, street dust, coal, diesel, sediments, lead ore and rainwater from India have been reported for the first time in this paper. This study characterized the source and extent of lead pollution in the different foodstuff consumed in Kolkata, a major metropolis of eastern India. The atmospheric lead input to the food items, sold openly in busy roadside markets of the city, has been quantified. The mean 207/206 and 208/206 LIRs of the eight food items ranged from 0.8847 to 0.8924 and 2.145 to 2.167, respectively. Diesel had the highest mean 207/206 and 208/206 values of 0.9015 and 2.1869, respectively, apart from the lead ore. The food items had a mean lead concentration between 3.78 and 43.35 mg kg^-1. The two ratio scatter plots of all the different environmental matrices were spread linearly between the uncontaminated Ichapur sediment and diesel. The 207/206 LIRs of the coal with a mean of 0.8777 did not fall in the linear trend, while the street dust and food samples overlapped strongly. The rainwater sample had a 207/206 LIR of 0.9007. Contaminated sediments in Dhapa, the repository of the city's municipal garbage, had a mean 207/206 LIR of 0.8658. The corresponding value obtained from the sewage-fed vegetable grown there was 0.8058. The present study indicated that diesel was one of the main contributor to Pb pollution. The atmospheric lead contribution to the food items was in the range of 68.48-86.66 %.

Associations between metals in residential environmental media and exposure biomarkers over time in infants living near a mining-impacted site

Infant exposures to metals are a concern for mining-impacted communities, although limited information is available to assess residential exposures over the first year of life. We measured lead (Pb), manganese, arsenic, and cadmium in indoor air, house dust, yard soil, and tap water from 53 infants' homes near the Tar Creek Superfund Site (Oklahoma, USA) at two time points representing developmental stages before and during initial ambulation (age 0-6 and 6-12 months). We measured infant metal biomarkers in: umbilical cord blood (n=53); 12- (n=43) and 24- (n=22) month blood; and hair at age 12 months (n=39). We evaluated cross-sectional and longitudinal associations between infant residential and biomarker concentrations. A doubling of mean dust Pb concentration was consistently associated with 36-49% higher 12-month blood Pb adjusting for cord blood Pb (P⩽0.05). Adjusted dust concentration explained 29-35% of blood Pb variance, and consistent associations with other media were not observed. Although concentrations in dust and blood were generally low, strong and consistent associations between dust and body burden suggest that house dust in mining-impacted communities may impact children's health. These relationships were observed at a young age, typically before blood Pb levels peak and when children's development may be particularly vulnerable to toxic insult.

Associations between metals in residential environmental media and exposure biomarkers over time in infants living near a mining-impacted site

Infant exposures to metals are a concern for mining-impacted communities, although limited information is available to assess residential exposures over the first year of life. We measured lead (Pb), manganese, arsenic, and cadmium in indoor air, house dust, yard soil, and tap water from 53 infants' homes near the Tar Creek Superfund Site (Oklahoma, USA) at two time points representing developmental stages before and during initial ambulation (age 0-6 and 6-12 months). We measured infant metal biomarkers in: umbilical cord blood (n=53); 12- (n=43) and 24- (n=22) month blood; and hair at age 12 months (n=39). We evaluated cross-sectional and longitudinal associations between infant residential and biomarker concentrations. A doubling of mean dust Pb concentration was consistently associated with 36-49% higher 12-month blood Pb adjusting for cord blood Pb (P⩽0.05). Adjusted dust concentration explained 29-35% of blood Pb variance, and consistent associations with other media were not observed. Although concentrations in dust and blood were generally low, strong and consistent associations between dust and body burden suggest that house dust in mining-impacted communities may impact children's health. These relationships were observed at a young age, typically before blood Pb levels peak and when children's development may be particularly vulnerable to toxic insult.

Screening for Elevated Blood Lead Levels in Children: Assessment of Criteria and a Proposal for New Ones in France

The decline in children’s Blood Lead Levels (BLL) raises questions about the ability of current lead poisoning screening criteria to identify those children most exposed. The objectives of the study were to evaluate the performance of current screening criteria in identifying children with blood lead levels higher than 50 µg/L in France, and to propose new criteria. Data from a national French survey, conducted among 3831 children aged 6 months to 6 years in 2008–2009 were used. The sensitivity and specificity of the current criteria in predicting blood lead levels higher than or equal to 50 µg/L were evaluated. Two predictive models of BLL above 44 µg/L (for lack of sufficient sample size at 50 µg/L) were built: the first using current criteria, and the second using newly identified risk factors. For each model, performance was studied by calculating the area under the ROC (Receiver Operating Characteristic) curve. The sensitivity of current criteria for detecting BLL higher than or equal to 50 µg/L was 0.51 (0.26; 0.75) and specificity was 0.66 (0.62; 0.70). The new model included the following criteria: foreign child newly arrived in France, mother born abroad, consumption of tap water in the presence of lead pipes, pre-1949 housing, period of construction of housing unknown, presence of peeling paint, parental smoking at home, occupancy rates for housing and child’s address in a cadastral municipality or census block comprising more than 6% of housing that is potentially unfit and built pre-1949. The area under the ROC curve was 0.86 for the new model, versus 0.76 for the current one. The lead poisoning screening criteria should be updated. The risk of industrial, occupational and hobby-related exposure could not be assessed in this study, but should be kept as screening criteria.

Investigating social inequalities in exposure to drinking water contaminants in rural areas

Few studies have assessed social inequalities in exposure to drinking water contaminants. This study explores this issue in 593 rural municipalities of Québec, Canada. Quartiles of an ecological composite deprivation index were used as a proxy of socioeconomic status. Total trihalomethanes (TTHMs) and lead were chosen as proxies of chemical drinking water quality. The results show that the majority of deprived rural municipalities apply no treatment to their water (26%) or use a basic treatment (51%), whereas a relative majority of the wealthiest municipalities (40%) use advanced treatment. The proportion of municipalities having important lead (>5 μg/L) levels is highest in most deprived municipalities. Moreover, most deprived municipalities have a higher risk of high tap lead levels (RR = 1.33; 95%CI: 1.30, 1.36). Conversely, most deprived municipalities have a lower risk of high TTHMs levels (RR = 0.78; 95%CI: 0.69, 0.86). These findings suggest an environmental inequality in drinking water contaminants distribution in rural municipalities.

Bioavailability-Based In Situ Remediation To Meet Future Lead (Pb) Standards in Urban Soils and Gardens

Recently the Centers for Disease Control and Prevention lowered the blood Pb reference value to 5 μg/dL. The lower reference value combined with increased repurposing of postindustrial lands are heightening concerns and driving interest in reducing soil Pb exposures. As a result, regulatory decision makers may lower residential soil screening levels (SSLs), used in setting Pb cleanup levels, to levels that may be difficult to achieve, especially in urban areas. This paper discusses challenges in remediation and bioavailability assessments of Pb in urban soils in the context of lower SSLs and identifies research needs to better address those challenges. Although in situ remediation with phosphate amendments is a viable option, the scope of the problem and conditions in urban settings may necessitate that SSLs be based on bioavailable rather than total Pb concentrations. However, variability in soil composition can influence bioavailability testing and soil amendment effectiveness. More data are urgently needed to better understand this variability and increase confidence in using these approaches in risk-based decision making, particularly in urban areas.

Screening for childhood lead poisoning in the industrial region of Fez, Morocco

The study objectives were to estimate lead poisoning prevalence among children living next to an industrial area, to compare it to that in a control population, and to establish clinical and biological follow-up of the poisoned children. This is a descriptive cross-sectional study including 150 children (exposed and unexposed) performed between January 2012 and April 2013. It was meant to determine blood lead levels (BLLs) in children considered to be an exposed population (EP N 90), living in the industrial area Ain Nokb Fez compared with BLLs of children of other areas belonging to the same city supposed to be unexposed [UP (N = 60)]. A sociodemographic questionnaire was obtained, and a blood lead analysis was performed. Clinical and biological follow-up has been performed of poisoned children. The sample consisted of 90 EP children with an average age of 6.82 ± 3.32 years and male-to-female sex ratio (SR) of 1.5 and 60 UP children with an average age of 6.45 ± 3.29 years and an SR of 1.2. Among the 150 children recruited, the average of BLLs was 58.21 ± 36 µg/L (18-202.3 μg/L). The average of BLLs in EP children (71 ± 40 µg/L) was statistically greater (p < 0.0001) than that registered in UP children (38 ± 13 µg/L). All poisoned children belonged to the EP group at a prevalence of 21.1 %. The clinical and biological examinations of poisoned children showed a few perturbations such as anemia, hypocalcaemia, and deficiencies in magnesium and iron. No renal disease or objective neurological disorders were observed. In the follow-up of the children with BLL ≥100 µg/L (19 cases). BLL monitoring showed a significant decrease in average of blood concentration ranging from 136.75 ± 32.59 to 104.58 ± 32.73 µg/L (p < 0.0001) and in lead poisoning prevalence (p < 0.001), which decreased to 7.8 % from 21.1. Our study showed a high prevalence of lead poisoning (21.1 %) in EP children. The relocation of the industrial site associated with corrective and preventive measures has contributed to a decrease of exposure and lead poisoning prevalence in the aforementioned population.

Environmental determinants of different blood lead levels in children: a quantile analysis from a nationwide survey

Blood lead levels (BLLs) have substantially decreased in recent decades in children in France. However, further reducing exposure is a public health goal because there is no clear toxicological threshold. The identification of the environmental determinants of BLLs as well as risk factors associated with high BLLs is important to update prevention strategies. We aimed to estimate the contribution of environmental sources of lead to different BLLs in children in France. We enrolled 484 children aged from 6months to 6years, in a nationwide cross-sectional survey in 2008-2009. We measured lead concentrations in blood and environmental samples (water, soils, household settled dusts, paints, cosmetics and traditional cookware). We performed two models: a multivariate generalized additive model on the geometric mean (GM), and a quantile regression model on the 10th, 25th, 50th, 75th and 90th quantile of BLLs. The GM of BLLs was 13.8μg/L (=1.38μg/dL) (95% confidence intervals (CI): 12.7-14.9) and the 90th quantile was 25.7μg/L (CI: 24.2-29.5). Household and common area dust, tap water, interior paint, ceramic cookware, traditional cosmetics, playground soil and dust, and environmental tobacco smoke were associated with the GM of BLLs. Household dust and tap water made the largest contributions to both the GM and the 90th quantile of BLLs. The concentration of lead in dust was positively correlated with all quantiles of BLLs even at low concentrations. Lead concentrations in tap water above 5μg/L were also positively correlated with the GM, 75th and 90th quantiles of BLLs in children drinking tap water. Preventative actions must target household settled dust and tap water to reduce the BLLs of children in France. The use of traditional cosmetics should be avoided whereas ceramic cookware should be limited to decorative purposes.

Persistent organic pollutants (POPs) and metals in primiparous women: a comparison from Canada and Mexico

Under the North American Commission for Environmental Cooperation (CEC) and its Sound Management of Chemicals (SMOC) program, a tri-national human contaminant monitoring initiative was completed to provide baseline exposure information for several environmental contaminants in Canada, Mexico and the United States (U.S). Blood samples were collected from primiparous women in Canada and Mexico, and were analysed for a suite of environmental contaminants including polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene(p,p'-DDE),beta-hexachlorocyclohexane (β-HCH), mercury and lead. A multiple stepwise linear regression analysis was conducted using data from Canadian and Mexican primiparous mothers, adjusting for ethnicity group, age, pre-pregnancy BMI, years at current city and ever-smoking status. Concentrations of p,p'-DDE, β-HCH, and lead were found to be higher among Mexican participants; however, concentrations of most PCBs among Mexican participants were similar to Canadian primiparous women after adjusting for covariates. Concentrations of total mercury were generally higher among Mexican primiparous women although this difference was smaller as age increased. This initial dataset can be used to determine priorities for future activities and to track progress in the management of the selected chemicals, both domestically and on a broader cooperative basis within North America.

Isotopic ratio based source apportionment of children's blood lead around coking plant area

Lead exposure in the environment is a major hazard affecting human health, particularly for children. The blood lead levels in the local children living around the largest coking area in China were measured, and the source of blood lead and the main pathways of lead exposure were investigated based on lead isotopic ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) in blood and in a variety of media, including food, airborne particulate matter, soil, dust and drinking water. The children's blood lead level was 5.25 (1.59 to 34.36 as range) μg dL(-1), lower than the threshold in the current criteria of China defined by the US Centers for Disease Control (10 μg dL(-1)). The isotopic ratios in the blood were 2.111±0.018 for (208)Pb/(206)Pb and 0.864±0.005 for (207)Pb/(206)Pb, similar to those of vegetables, wheat, drinking water, airborne particulate matter, but different from those of vehicle emission and soil/dust, suggesting that the formers were the main pathway of lead exposure among the children. The exposure pathway analysis based on the isotopic ratios and the human health risk assessment showed that dietary intake of food and drinking water contributed 93.67% of total exposed lead. The study further indicated that the coal used in the coking plant is the dominant pollution source of lead in children's blood.

Identification of environmental sources of lead exposure in Nunavut (Canada) using stable isotope analyses

BACKGROUND

Blood lead levels (BLLs) were measured in the adult Inuit population of Nunavut, Northern Canada, during the Inuit Health Survey (IHS) in 2007-2008. Approximately 10% of the adult participants had BLL over the Health Canada's guidance of 100μg/L.

OBJECTIVES

1) To repeat the measurement of BLL among the IHS participants with high BLL and household members including pregnant women and children under 10years of age; 2) to measure lead (Pb) concentrations in environmental samples to identify potential sources and 3) to explore how Pb from environmental samples contributes to BLL using Pb stable isotopic analyses.

METHODS

Blood samples were collected from 100 adults and 56 children in 2012. A total of 169 environmental samples (tap water, house dust, paint, country food, soil, and ammunition) were collected from 14 houses from three communities where the IHS participants had the highest BLL. Total Pb concentrations and Pb isotope mass balance were determined by inductively coupled plasma-mass spectrometry (ICP-MS).

RESULTS

The geometric mean of BLL was 43.1μg/L; BLL increased with age and was higher in adults than children (71.1 vs. 17.5μg/L). Median Pb concentrations in water (1.9μg/L) and dust (27.1μg/m(2) for wiped dust, 32.6mg/kg for vacuum dust coarse fraction, and 141.9mg/kg for vacuum dust fine fraction) were generally higher than in other parts of Canada. Median Pb concentrations of food and soil coarse and fine fractions were low (36.6μg/kg, 5.4mg/kg and 11.8mg/kg respectively); paint chips exceeded the Canadian guidelines in two houses (median: 3.8mg/kg). Discriminant analyses and isotope ratio analyses showed that ammunition and house dust are major sources of Pb in this study population.

CONCLUSION

Analyses of Pb stable isotopes are useful to identify the routes of exposure to Pb. This approach can contribute to develop targeted public health programmes to prevent Pb exposure.

Pathways of Pb and Mn observed in a 5-year longitudinal investigation in young children and environmental measures from an urban setting

We monitored 108 children ≤5 years on a 6-month basis for up to 5 years in a major urban setting. Samples (n ∼ 7000) included blood, urine, handwipes (interior, and after exterior playing), 6-day duplicate diet, drinking water, interior house and day care dust-fall accumulation using petri dishes, exterior dust-fall accumulation, exterior dust sweepings, paint, soil and urban air. The geometric mean blood Pb (PbB) was 2.1 μg/dL and blood Mn (MnB) was 10.0 μg/L. Following a path modelling approach, mixed model analyses for a fully adjusted model showed the strongest associations for PbB were with interior house dust and soil; for MnB there were no significant associations with any predictors. Predictor variables only explained 9% of the variance for Pb and 0.7% for Mn. Relationships between environmental measures and PbB in children are not straightforward; soil and dust sweepings contribute only about 1/5th of the amounts to PbB found in other studies.

Blood lead levels and risk factors in young children in France, 2008-2009

BACKGROUND

The exposure of children to lead has decreased in recent years, thanks notably to the banning of leaded gasoline. However, lead exposure remains a matter of public health concern, because no toxicity threshold has been observed, cognitive effects having been demonstrated even at low levels. It is therefore important to update exposure assessments. A national study was conducted, in 2008-2009, to determine the blood lead level (BLL) distribution in children between the ages of six months and six years in France. We also assessed the contribution of environmental factors.

METHODS

This cross-sectional survey included 3831 children recruited at hospitals. Two-stage probability sampling was carried out, with stratification by hospital and French region. Sociodemographic characteristics were recorded, and blood samples and environmental data were collected by questionnaire. Generalized linear model and quantile regression were used to quantify the association between BLL and environmental risk factors.

RESULTS

The geometric mean BLL was 14.9μg/l (95% confidence interval (CI)=[14.5-15.4]) and 0.09% of the children (95% CI=[0.03-0.15]) had BLLs exceeding 100μg/l, 1.5% (95% CI=[0.9-2.1] exceeding 50μg/l. Only slight differences were observed between French regions. Environmental factors significantly associated with BLL were the consumption of tap water in homes with lead service connections, peeling paint or recent renovations in old housing, hand-mouth behavior, passive smoking and having a mother born in a country where lead is often used.

CONCLUSIONS

In children between the ages of one and six years in France, lead exposure has decreased over the last 15 years as in the US and other European countries. Nevertheless still 76,000 children have BLL over 50μg/l and prevention policies must be pursued, especially keeping in mind there is no known toxicity threshold.

Status of metal levels and their potential sources of contamination in Southeast Asian rivers

To assess the concentration and status of metal contaminants in four major Southeast Asian river systems, water were collected from the Tonle Sap-Bassac Rivers (Cambodia), Citarum River (Indonesia), lower Chao Phraya River (Thailand), and Saigon River (Vietnam) in both dry and wet seasons. The target elements were Be, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Ba, Tl, and Pb and the concentrations exceeded the background metal concentrations by 1- to 88-fold. This distinctly indicates enrichment by human urban area activities. The results of a normalization technique used to distinguish natural from enriched metal concentrations confirmed contamination by Al, Cd, Co, Mn, Ni, Pb, and Zn. Cluster analysis revealed the probable source of metals contamination in most sampling sites on all rivers studied to be anthropogenic, including industrial, commercial, and residential activities. Stable lead isotopes analyses applied to track the sources and pathways of anthropogenic lead furthermore confirmed that anthropogenic sources of metal contaminated these rivers. Discharges of wastewater from both industrial and household activities were major contributors of Pb into the rivers. Non-point sources, especially road runoff and street dust, also contributed contamination from Pb and other metals.

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.