The pediatric burden of disease from lead exposure at toxic waste sites in low and middle income countries

The physicochemical interacting mechanisms and real-time spectral induced polarization monitoring of lead remediation by an aeolian soil

Compared to traditional lead-remediating materials, natural-occurring paleosol is ubiquitous and could be a promising alternative due to its rich content in calcite, a substance known for its lead-removal ability via carbonate dissolution-PbCO3 precipitation process. Yet, the capability of paleosol to remediate aqueous solutions polluted with heavy metals, lead included, has rarely been assessed. To fill this gap, a series of column permeation experiments with influent Pb2+ concentrations of 2000, 200, and 20 mg/L were conducted and monitored by the spectral induced polarization technique. Meanwhile, the SEM-EDS, XRD, XPS, FTIR and MIP tests were carried out to unveil the underlying remediation mechanisms. The Pb-retention capacity of paleosol was 1.03 mmol/g. The increasing abundance of Pb in the newly-formed crystals was confirmed to be PbCO3 by XRD, SEM-EDS and XPS. Concurrently, after Pb2+ permeation, the decreasing calcite content in paleosol sample from XRD test, and the appearance of Ca2+ in the effluent confirmed that the dissolution of CaCO3 followed by the precipitation of PbCO3 was the major mechanism. The accumulated Pb (i.e., the diminished Ca) in paleosol was inversely proportional (R2 >0.82) to the normalized chargeability (mn), an SIP parameter denoting the quantity of polarizable units (primarily calcite).

Risk Analysis Approaches to Evaluating Health Impacts from Land-Based Pollution in Low- and Middle-Income Countries

Risk analysis offers a useful framework for evaluating and managing environmental health risks across different settings. In this Perspective, we question whether the principles and practice of risk analysis could be beneficial in the context of land-based pollution in low- and middle-income countries (LMICs) to better support risk-based decision making. Specifically, potential health and economic impacts from land-based pollution in LMICs has become an increasing issue of concern due to widespread environmental contamination from active and legacy operations, particularly informal activities that are becoming increasingly dispersed throughout communities, such as used lead acid battery recycling, artisanal and small-scale gold mining, and small-scale tanneries. However, the overall magnitude and scale of the public health problem arising from these sources remains highly uncertain and poorly characterized and cannot be compared to land-based pollution in high-income countries due to unique factors. This lack of knowledge has negatively affected the political priority and level of funding for risk mitigation actions targeting land-based pollution in these countries. Our primary objective is to raise further awareness of this emerging issue among risk analysts and decisionmakers and to advocate for more robust and focused research. Here, we highlight the types of industries and activities contributing to land-based pollution in LMICs and describe key findings and knowledge and data gaps that have hindered a fuller understanding of this issue. We also discuss how several risk assessment and risk management approaches might be useful in this resource-constrained context. We conclude that a combination of risk analysis approaches may be worthwhile, but more work is needed to determine which methods or tools will be most informative, technically feasible, and cost-effective for identifying, prioritizing, and mitigating land-based pollution in LMICs. Affected researchers, funding agencies, and local or national governments will need to work together to develop improved study designs and risk mitigation strategies.

Neurodevelopment and exposure to neurotoxic metal(loid)s in environments polluted by mining, metal scrapping and smelters, and e-waste recycling in low and middle-income countries

This review covers a wide body of literature to gain an understanding of the impacts of informal activities related to metal extraction (primary mining and recycling) on early life exposure to neurotoxicants and on neurodevelopment. In primary mining, gold extraction with Hg amalgamation is the main environmental cause of Hg pollution in most artisanal small-scale gold mining (ASGM) activities around the world. Nevertheless, in Sub-Saharan Africa (SSA), Pb disrupted from gold-related ores, mining, and artisanal cookware production are an important neurotoxicant that seriously contaminates the affected population, with devastating effects on children. In e-waste recycling settings, the range of neurotoxic substances that contaminate mothers and children is wider than in primary mining environments. Thus, Hg and Pb are major pre- and postnatal neurotoxicants affecting children in the informal metal extraction activities and SSA countries show the highest record of human contamination and of neurotoxic effects on children. There are additional sources of neurotoxic contamination from mining and metal processing activities (cyanide tailing in South America and SSA) and/or co-exposure to Hg-containing products such as cosmetics (soaps and Hg-based skin lightning creams in Africa) and pediatric Thimerosal-containing vaccines (TCVs, that breaks down to ethyl-mercury) in current use in middle and low income countries. However, the action of these neurotoxicants (per se or in combination) on children needs more attention and research. Studies show a negative association between biomarkers of all environmental metal(loid)s (As, Cd, Hg, Mn, and Pb) studied and neurodevelopment in young children. Sadly, in many unregulated activities, child labor is widely employed, thus presenting an additional occupational exposure. Children living in polluted environments related to metal processing are disproportionately exposed to a wide range of co-occurring neurotoxic substances. The review showed compelling evidence from highly representative parts of the world (Africa, Asia, and Latin America) that the studied neurotoxic substances negatively affected areas of the brain associated with language, memory and executive function, as well as psychosocial behavior. Protecting the environment and children from unregulated and highly polluting metal extraction and processing are inextricably intertwined and deserve urgent attention.

Exposure to environmental neurotoxic substances and neurodevelopment in children from Latin America and the Caribbean

Environmental (and occupational) exposure to neurotoxic substances is a worldwide problem that can affect children's neurodevelopment (ND). In Latin American and Caribbean (LAC) countries there are over 300 million children living under the threat of neurodevelopmental delays due to toxic environmental exposure. Large industrial centers, intense mining and agricultural activities, along with changing complex ecosystems constitute a mosaic that drives contamination of air, water and the food chain. Neurotoxic contaminants such as pesticides (organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, and manganese fungicides), chemicals of industrial use (phthalates), and metals (Hg, Pb, Al, As, F, Cd, Mo, Mn) are at the center of environmental exposure studies. Exposure to neurotoxic substances singly or in combination with other compounds or socioeconomic stressors (maternal education, socio-economic and nutritional status) intertwined with occupational and para-occupational exposure can affect ND (motor, cognition, behavior) of children. Significant negative effects of pesticides and neurotoxic elements on ND were found in all studied countries, affecting especially the less-privileged children from laboring families. Studies showed that exposures to the neurotoxicants in human milk are secondary to their more lasting effects during prenatal exposure. This review integrates exposure (prenatal and breastfeeding), metabolism, and ND effects of neurotoxicants. It highlights the overwhelming evidence showing that current levels of exposures are hazardous and detrimental to children's ND in LAC countries. The evidence indicates that a reduction in neurotoxicant exposure is essential to protect children's ND. Therefore, it is urgent to adopt policies and actions that prevent and remediate region-specific children's ND issues.

Probabilistic estimates of prenatal lead exposure at 195 toxic hotspots in low- and middle-income countries

BACKGROUND

Prior estimates of pediatric lead-related disease burden in low- and middle-income countries (LMICs) used population estimates of maternal blood lead levels (BLLs). This approach may underestimate fetal BLLs by not considering potentially high prenatal lead exposure from toxic hotspots. OBJECTIVES: We developed a probabilistic approach to using the Adult Lead Methodology (ALM) to estimate fetal BLLs from prenatal exposure to lead-contaminated soil at hotspots in the Toxic Site Identification Program (TSIP).

METHODS

We created distributions for each ALM parameter using published literature and extracted soil lead measurements from the TSIP database. Each iteration of the probabilistic ALM randomly selected values from the input distributions to generate a site-specific fetal BLL estimate. For each site, we ran 5000 model iterations, producing a site-specific fetal BLL distribution.

RESULTS

195 TSIP sites, in 33 LMICs, met our study inclusion criteria; an estimated 820,000 women of childbearing age are at risk for lead exposure at these sites. The predicted geometric means (GM) for site-specific fetal BLLs ranged from 3.3 μg/dL to 534 μg/dL, and 98% of sites had estimated GM fetal BLLs >5 μg/dL, the current reference level of the United States Centers for Disease Control and Prevention (CDC), while 11 sites had estimated GM fetal BLLs above the CDC chelation threshold of 45 μg/dL.

DISCUSSION

The TSIP soil lead data and this probabilistic approach to the ALM show that pregnant women living near TSIP sites may have BLLs that put their fetus at risk for neurologic damage and other sequelae, underscoring the need for interventions to reduce lead exposure at toxic hotspots.

Estimating the national burden of mild intellectual disability in children exposed to dietary lead in China

The effects of lead as a dietary pollutant remain a global public health concern that needs urgent resolution. Children are highly susceptible to the adverse outcomes of lead pollution, as even low levels of lead may cause irreversible damage to intellectual development. Since several sources of lead exposure are present in the environment, it is necessary to identify the attributable burden of lead-related diseases arising from different exposure sources. In the present study, we used epidemiological data from studies around the nation to estimate the burden of mild intellectual disability (MID) attributed to lead exposure sources by using disability-adjusted life years (DALYs). To this end, a dose-response approach was used and a model comprising three components was established: exposure, dose-response, and DALYs module. In Chinese children aged 0-6 years, blood lead levels (BLLs) of 5.34 ± 3.09 μg/dL resulted in a MID incidence rate of 12.84 cases per 1000 children, with an estimated burden of disease (BoD) of 42.23 DALYs per 1000 children. Owing to dietary lead exposure, 36.64 healthy life years per 1000 children were lost, which was notably higher than the outcomes associated with exposure from other sources. This was consistent with the result that dietary exposure was the main contributor to children's lead exposure, accounting for 86.76%. According to the regional distribution based on the existing literature, the areas in China with higher BLLs were Heilongjiang, Shanxi, and Jiangxi. Our findings provided the information for lead risk management decisions and policies making.

Using disability-adjusted life years to estimate the cancer risks of low-level arsenic in drinking water

Recent studies have shown that long-term exposure to low-level arsenic (<10 μg/L) may cause human health problems. However, the induced cancer risks and differences among multisite cancers have not been well-understood. In this study, the concentrations of low-level arsenic in drinking water in XP city, Northwest China were investigated. A health risk assessment was carried out for different age groups and exposure pathways based on Monte Carlo simulations and disability-adjusted life years (DALYs). The measured arsenic levels were in the range of 7.61-9.25 μg/L with a mean of 8.23 μg/L. For the public, the average total lifetime cancer risk was 3.87 × 10^-4, and the total DALYs estimation for all age groups was 20.58 person-year. The average individual DALYs lost was 3.35 × 10^-5 per person-year (ppy), which was 33.5 times the reference value (1.00 × 10^-6 ppy). The mortality burden had a considerably larger contribution (97.31%) to the total disease burden, and the 60-65-year age group exhibited the largest DALYs lost. Skin cancer exhibited the largest burden of 2.15 × 10^-5 ppy, followed by lung cancer (1.20 × 10^-5 ppy). This study might be useful for potential strategies of risk control and management in XP drinking water.

Estimating and comparing the cancer risks from THMs and low-level arsenic in drinking water based on disability-adjusted life years

To determine the priority hazard in drinking water, disability-adjusted life years (DALYs) method was used to evaluate the disease burden induced by trihalomethanes (THMs) and low-level arsenic through multiple exposure routes based on the two-year sampling from drinking water in Xi'an city, Northwest China. The average concentrations of chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), bromoform (TBM) and arsenic were 12.67 μg/L, 1.42 μg/L, 0.60 μg/L, 0.13 μg/L and 1.00 μg/L, respectively, and the total lifetime cancer risks for all THMs and arsenic were 8.54 × 10^-6 and 4.02 × 10^-5, which were 8.54 and 40.2 times of the negligible risk level (1.00 × 10^-6), respectively. The DALYs estimation showed that the total DALYs lost for all age groups was 32.62 person-year, and the average individual DALYs lost was 4.77 × 10^-6 per person-year (ppy), which was 4.77 times of the reference level (1.00 × 10^-6 ppy). About 72.07% of the total disease burden was due to arsenic, which was considered to be the priority hazard in Xi'an drinking water. The age group of 75-80 years was found to be most vulnerable to the induced cancer risk, and skin cancer had the highest disease burden (2.24 × 10^-6 ppy). Due to the relatively high incidence rates of lung cancer and skin cancer, most DALYs lost for males were 2-4 times to that for females in the same age group. Oral ingestion made the most contribution (88.58%) to the total disease burden, followed by inhalation of THMs (11.30%), whereas dermal absorption showed negligible risk (0.12%). As the first to compare the cancer risks of arsenic and THMs to the public in DALYs in China, this study might be useful for potential strategies of risk control and management of hazardous agents in drinking water.

Calculation of the disease burden associated with environmental chemical exposures: application of toxicological information in health economic estimation

Calculation of costs and the Burden of Disease (BoD) is useful in developing resource allocation and prioritization strategies in public and environmental health. While useful, the Disability-Adjusted Life Year (DALY) metric disregards subclinical dysfunctions, adheres to stringent causal criteria, and is hampered by gaps in environmental exposure data, especially from industrializing countries. For these reasons, a recently calculated environmental BoD of 5.18% of the total DALYs is likely underestimated. We combined and extended cost calculations for exposures to environmental chemicals, including neurotoxicants, air pollution, and endocrine disrupting chemicals, where sufficient data were available to determine dose-dependent adverse effects. Environmental exposure information allowed cost estimates for the U.S. and the EU, for OECD countries, though less comprehensive for industrializing countries. As a complement to these health economic estimations, we used attributable risk valuations from expert elicitations to as a third approach to assessing the environmental BoD. For comparison of the different estimates, we used country-specific monetary values of each DALY. The main limitation of DALY calculations is that they are available for few environmental chemicals and primarily based on mortality and impact and duration of clinical morbidity, while less serious conditions are mostly disregarded. Our economic estimates based on available exposure information and dose-response data on environmental risk factors need to be seen in conjunction with other assessments of the total cost for these environmental risk factors, as our estimate overlaps only slightly with the previously estimated environmental DALY costs and crude calculations relying on attributable risks for environmental risk factors. The three approaches complement one another and suggest that environmental chemical exposures contribute costs that may exceed 10% of the global domestic product and that current DALY calculations substantially underestimate the economic costs associated with preventable environmental risk factors. By including toxicological and epidemiological information and data on exposure distributions, more representative results can be obtained from utilizing health economic analyses of the adverse effects associated with environmental chemicals.

Transgenerational epigenetics and environmental justice

Human transmission to offspring and future generations of acquired epigenetic modifications has not been definitively established, although there are several environmental exposures with suggestive evidence. This article uses three examples of hazardous substances with greater exposures in vulnerable populations: pesticides, lead, and diesel exhaust. It then considers whether, if there were scientific evidence of transgenerational epigenetic inheritance, there would be greater attention given to concerns about environmental justice in environmental laws, regulations, and policies at all levels of government. To provide a broader perspective on environmental justice the article discusses two of the most commonly cited approaches to environmental justice. John Rawls's theory of justice as fairness, a form of egalitarianism, is frequently invoked for the principle that differential treatment of individuals is justified only if actions are designed to benefit those with the greatest need. Another theory, the capabilities approach of Amartya Sen and Martha Nussbaum, focuses on whether essential capabilities of society, such as life and health, are made available to all individuals. In applying principles of environmental justice the article considers whether there is a heightened societal obligation to protect the most vulnerable individuals from hazardous exposures that could adversely affect their offspring through epigenetic mechanisms. It concludes that unless there were compelling evidence of transgenerational epigenetic harms, it is unlikely that there would be a significant impetus to adopt new policies to prevent epigenetic harms by invoking principles of environmental justice.

Environmental Exposures and Cardiovascular Disease: A Challenge for Health and Development in Low- and Middle-Income Countries

Environmental exposures in low- and middle-income countries lie at the intersection of increased economic development and the rising public health burden of cardiovascular disease. Increasing evidence suggests an association of exposure to ambient air pollution, household air pollution from biomass fuel, lead, arsenic, and cadmium with multiple cardiovascular disease outcomes, including hypertension, coronary heart disease, stroke, and cardiovascular mortality. Although populations in low- and middle-income countries are disproportionately exposed to environmental pollution, evidence linking these exposures to cardiovascular disease is derived from populations in high-income countries. More research is needed to further characterize the extent of environmental exposures.

Metal Concentrations in Newcomer Women and Environmental Exposures: A Scoping Review

Newcomer women from developing countries are recognized to be at risk for elevated exposures to environmental contaminants and associated negative health effects. As such, data on exposure sources and contaminant body burden concentrations is critical in the development of effective public health policies and interventions in support of newcomer health. We conducted a scoping review to gather evidence on important toxic metals of health concern, lead (Pb), mercury (Hg) and cadmium (Cd), and their concentrations and potential exposure sources among newcomer women. An initial 420 articles were identified through the databases MEDLINE, EMBASE and Scopus, many reporting by ethnicity rather than newcomer/immigrant status. Several articles reported metal concentrations for other biomarkers but did not include blood, nor stratify results. From the remainder, we selected a total of 10 articles for full textual review, which reported blood Pb, Hg or Cd levels for newcomer women and/or stratified blood metal results according to foreign birth or country of origin. Three of the articles reported higher Pb, Hg and Cd concentrations in newcomer women compared to their native-borne counterparts. Exposures identified as contributing to elevated Pb, Hg and Cd blood concentrations included: pica behaviour, the use of lead-glazed cookware or eye cosmetics, and fish/shellfish consumption. The review revealed a limited availability of data on metal body burden concentrations, exposure sources and routes among newcomer women specifically. More research is needed to better understand the extent to which newcomer women are disproportionately at risk of elevated metal exposures due to either country of origin or current exposures and to inform relevant, multi-national risk management strategies.

Application of IEUBK model in lead risk assessment of children aged 61-84 months old in central China

Few studies have focused on the accuracy of using the Integrated Exposure Uptake Biokinetic (IEUBK) model in Chinese children with site- and age-specific exposure data. This study aimed to validate the accuracy and sensitivity of the IEUBK model in lead risk assessment of Chinese children aged 61-84 months old. A total of 760 children were enrolled from two respective counties in Central China by using random cluster sampling method. Blood lead levels (BLLs) of all subjects were determined using graphite furnace atomic absorption spectrometry, as well as that in the environmental media, such as air, drinking water, soil, dust and food. Age- and site-specific time-activity patterns and water consumption were evaluated by using questionnaires for children. Exposure parameters including outdoor and indoor activity time, ventilation rate and water consumption in this study were different from the default values of the IEUBK model. Statistical analysis revealed no significant differences between the predicted and observed BLLs. Diet and soil/dust lead intake contributed approximately 83.39% (57.40%-93.84% range) and 15.18% (3.25%-41.60% range) of total lead intake, respectively. These findings showed that the IEUBK model is suitable for lead risk assessment of Chinese children aged 61-84 months old and diet acts as an important lead source.