A review of soil and dust ingestion studies for children

Can metals and radionuclides in Shiveluch (Kamchatka) volcanic ash affect human health?

Volcanic eruption is associated with the release of large volumes of pollutants in the environment, which can pose a risk to humans and other living organisms. The elemental and radioisotope composition of ash released during the Shiveluch Volcano eruption in 2023 was analyzed using ICP-MS and low-background gamma spectrometry. The ash consisted of 59% SiO2, 16.7% Al2O3, 5.3% CaO, 4.6 % Na2O, 4.5% Fe2O3, 1.4% K2O, 0.48% TiO2, 0.17% P2O5, 0.15% S, 0.078% MnO and 44 trace elements. Hazard Quotient and Hazard Index were calculated in order to evaluate the potential health risks to children and adults due to exposure to contaminants via inhalation, ingestion, and dermal contact. All values were below the unit, indicating a low probability of non-carcinogenic and cancerogenic risk occurrence in target groups. The average activity concentrations of the natural radionuclides were 350, 12.4 and 4.84 Bq/kg for 40K, 226Ra and 232Th. Radiological indices, including external and internal risk assessment, radium equivalent activity, annual effective dose, gamma index, and excess lifetime cancer risk were calculated to estimate the radiological hazard for the population. The values of all indices were below the recommended safety limits, indicating a low level of hazard for the exposed population.

Biocide and other semi-volatile organic compound concentrations in settled indoor dust of CRESPI daycare centers and implication for public health

This study investigates the presence of biocides and other semi-volatile organic compounds (SVOCs) in cleaning products used in daycare centers and health impact through ingestion of settled dust by young children. In Paris metropolitan area, 106 daycares area were investigated between 2019-2022. Fifteen substances were analyzed in settled indoor dust by gas chromatography-tandem mass spectrometry. Detection rates and concentrations ranged from 5 to 100%, and Collapse

Key Words

• Day nurseries
• Dust ingestion
• Health relevance
• Oral exposure
• SVOCs

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MESH Headings

• Dust/analysis
• Humans
• Volatile Organic Compounds/analysis
• Child Day Care Centers
• Air Pollution, Indoor/analysis
• Disinfectants/analysis
• Infant
• Public Health
• Environmental Monitoring
• Child, Preschool

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Affiliation(s)

Mayoro Kebe Mane Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) - UMR_S 1085, F-35000 Rennes, France.
Gaëlle Raffy Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) - UMR_S 1085, F-35000 Rennes, France.
Philippe Glorennec Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) - UMR_S 1085, F-35000 Rennes, France.
Nathalie Bonvallot Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) - UMR_S 1085, F-35000 Rennes, France.
Pierre Bonnet Scientific and Technical Center for Building (CSTB), Indoor Environment Quality Unit, 77420 Champs-sur-Marne, France.
Orianne Dumas Université Paris-Saclay, UVSQ, Univ. Paris-Sud, Inserm, Équipe d'Épidémiologie Respiratoire Intégrative, CESP, 94807 Villejuif, France.
Anastasie Eworo Nchama Université Paris-Saclay, UVSQ, Univ. Paris-Sud, Inserm, Équipe d'Épidémiologie Respiratoire Intégrative, CESP, 94807 Villejuif, France.
Gaëlle Saramito Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) - UMR_S 1085, F-35000 Rennes, France.
Camille Duguépéroux Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) - UMR_S 1085, F-35000 Rennes, France.
Corinne Mandin Scientific and Technical Center for Building (CSTB), Indoor Environment Quality Unit, 77420 Champs-sur-Marne, France.
Nicole Le Moual Université Paris-Saclay, UVSQ, Univ. Paris-Sud, Inserm, Équipe d'Épidémiologie Respiratoire Intégrative, CESP, 94807 Villejuif, France.
Barbara Le Bot Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) - UMR_S 1085, F-35000 Rennes, France.

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Endocrine disrupting potential of total and bioaccessible extracts of dust from seven different types of indoor environment

Information on the indoor environment as a source of exposure with potential adverse health effects is mostly limited to a few pollutant groups and indoor types. This study provides a comprehensive toxicological profile of chemical mixtures associated with dust from various types of indoor environments, namely cars, houses, prefabricated apartments, kindergartens, offices, public spaces, and schools. Organic extracts of two different polarities and bioaccessible extracts mimicking the gastrointestinal conditions were prepared from two different particle size fractions of dust. These extracts were tested on a battery of human cell-based bioassays to assess endocrine disrupting potentials. Furthermore, 155 chemicals from different pollutant groups were measured and their relevance for the bioactivity was determined using concentration addition modelling. The exhaustive and bioaccessible extracts of dust from the different microenvironments interfered with aryl hydrocarbon receptor, estrogen, androgen, glucocorticoid, and thyroid hormone (TH) receptor signalling, and with TH transport. Noteably, bioaccessible extracts from offices and public spaces showed higher estrogenic effects than the organic solvent extracts. 114 of the 155 targeted chemicals were detectable, but the observed bioactivity could be only marginally explained by the detected chemicals. Diverse toxicity patterns across different microenvironments that people inhabit throughout their lifetime indicate potential health and developmental risks, especially for children. Limited data on the endocrine disrupting potency of relevant chemical classes, especially those deployed as replacements for legacy contaminants, requires further study.

Innovative non-targeted screening approach using High-resolution mass spectrometry for the screening of organic chemicals and identification of specific tracers of soil and dust exposure in children

Environmental contamination through direct contact, ingestion and inhalation are common routes of children's exposure to chemicals, in which through indoor and outdoor activities associated with common hand-to-mouth, touching objects, and behavioral tendencies, children can be susceptible and vulnerable to organic contaminants in the environment. The objectives of this study were the screening and identification of a wide range of organic contaminants in indoor dust, soil, food, drinking water, and urine matrices (N = 439), prioritizing chemicals to assess children's environmental exposure, and selection of unique tracers of soil and dust ingestion in young children by non-targeted analysis (NTA) using Q-Exactive Orbitrap followed data processing by the Compound Discoverer (v3.3, SP2). Chemical features were first prioritized based on their predominant abundance (peak area>500,000), detection frequency (in >50% of the samples), available information on their uses and potential toxicological effects. Specific tracers of soil and dust exposure in children were selected in this study including Tripropyl citrate and 4-Dodecylbenzenesulfonic acid. The criteria for selection of the tracers were based on their higher abundance, detection frequency, unique functional uses, measurable amounts in urine (suitable biomarker), and with information on gastrointestinal absorption, metabolism, and excretion, and were further confirmed by authentic standards. We are proposing for the first time suitable unique tracers for dust ingestion by children.

There's Something in What We Eat: An Overview on the Extraction Techniques and Chromatographic Analysis for PFAS Identification in Agri-Food Products

Per- and polyfluorinated alkyl substances (PFASs) are a group of anthropogenic chemicals used in a range of industrial processes and consumer products. Recently, their ubiquitous presence in the environment as well as their toxicological effects in humans have gained relevant attention. Although the occurrence of PFASs is widely investigated in scientific community, the standardization of analytical method for all matrices still remains an important issue. In this review, we discussed extraction and detection methods in depth to evaluate the best procedures of PFAS identification in terms of analytical parameters (e.g., limits of detection (LODs), limits of quantification (LOQs), recoveries). Extraction approaches based on liquid-liquid extraction (LLE), alkaline digestion, and solid phase extraction (SPE), followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis are the main analytical methods applied in the literature. The results showed detectable recoveries of PFOA and PFOS in meat, milk, vegetables, eggs products (90.6-101.2% and of 89.2-98.4%), and fish (96-108%). Furthermore, the low LOD and LOQ values obtained for meat (0.00592-0.01907 ng g-1; 0.050 ng g-1), milk (0.003-0.009 ng g-1; 0.010-0.027 ng g-1), fruit (0.002-0.009 ng g-1; 0.006-0.024 ng g-1), and fish (0.00369-0.017.33 ng g-1; 0.05 ng g-1) also confirmed the effectiveness of the recent quick, easy, cheap, effective, rugged, and safe method (QuEChERS) for simple, speedy, and sensitive ultra-trace PFAS analysis.

Integrative assessment of urban dust polycyclic aromatic hydrocarbons using ground and satellite data in Iran

Recently, for quick urbanization and industrialization, pollutants, especially urban dust, have posed many threats to the human environment. Polycyclic aromatic hydrocarbons (PAHs) are regarded as the main dangerous pollutants that are widespread, persistent, and carcinogenic. The present work aimed to investigate the contamination and sources of PAHs, as well as to assess the risk of cancer for 16 priority PAHs, in urban dust samples in Ahvaz, Isfahan, and Shiraz cities in Iran. We measured PAH concentrations by gas chromatography-mass spectrometry (GC-MS). The average concentrations of the 16 PAHs in Ahvaz, Isfahan, and Shiraz were 6215.11, 7611.03, and 7810.37 μg kg-1, respectively. The domination of low-molecular-weight (LMW) PAHs was observed in Ahvaz, while maximum contribution was observed for high-molecular-weight (HMW) PAHs in Esfahan and Shiraz. For PAHs' source identification, diagnostic ratio, correlation analysis, clustering, and positive matrix factorization (PMF) model were used. PAHs had a combustion (coal and wood, oil, fossil fuels) and gasoline/diesel engine emissions in all cities. Comparative studies suggest that the PAH compounds' level is higher in the research area than in other countries, except for China and India. Also, the pollution of urban dust PAHs has increased over time compared to previous studies in the same cities. The cancer risk from exposure to dust contaminated with PAHs was assessed using the Incremental Lifetime Cancer Risk (ILCR) model. According to the findings, a high risk of exposure to cancer was observed in Ahvaz, Isfahan, and Shiraz. However, compared to adults, children are at higher risk of cancer in their daily lives via dermal contact and unconscious ingestion. Based on the ILCR values, the risk of cancer is in the order of Shiraz > Isfahan > Ahvaz. To assess air pollutants and their effects on urban dust, TROPOMI onboard the Sentinel-5P data were used in the studied cities during 2018-2021. The results show that Ahvaz has different high levels of CO compared to the other 2 cities. Also, Isfahan has different high levels of NO2 compared to the other 2 cities, but Shiraz has different low levels of O3. According to satellite time series data, the trend of the Aerosol Absorbing Index (AAI) has been increasing, while there was a decreasing trend in AAI from the beginning of the COVID-19 pandemic until 12 months later. Therefore, the natural and anthropogenic sources of urban dust PAHs have been increasing in all studied cities. Our findings show that PAH compounds in urban dust pose a significant threat to human health. Therefore, strategic management and planning are vital in reducing urban dust pollution.

Advancing Methodologies Used in Trace Element-Based Mass Balance Studies to Separately Estimate Soil and Dust Ingestion Rates for Children

Historically, soil ingestion rate estimates were based on trace element-based mass balance (MB) study results. These were used in assessing exposures and health risks for children residing in Superfund or chemically contaminated communities. However, soil and dust can have considerable differences with respect to their sources, chemical, physical, and toxicological characteristics. Unfortunately, the MB approach is incapable of disentangling dust ingestion rates from soil ingestion rates. Alternative methods, such as activity pattern and biokinetic modeling techniques, have also been used to predict soil and dust ingestion rates. The results from these studies differed from those obtained from the MB studies. This research evaluated the MB methodology and formulated a physical model which characterized the environmental and behavioral determinants of soil and dust ingestion exposures by children. This new approach explicitly separates outdoor soil exposures from the indoor tracked-in soil portion of the dust and total dust exposures by utilizing information from five key MB studies along with new information derived from the SHEDS-Soil/Dust time-activity pattern-based modeling runs. Application of this new hybrid methodology showed that the predicted mean soil ingestion rates are 30%-70% less than the "total soil" ingestion rates obtained from the selected MB studies. In contrast, most of the predicted dust ingestion rate estimates were typically greater than the predicted soil ingestion rates. Moreover, the predicted total soil plus dust ingestion rates were found to be mostly higher (by ≤ 60%) than the MB-based "total soil" ingestion rates. Except for one study these results were higher than the results produced by the stand-alone SHEDS-Soil/Dust model runs. Across the MB studies analyzed, predicted outdoor soil ingestion rate contributions to "total soil" ingestion rates varied between 29% and 70% while the tracked-in soil portion of the indoor dust ingestion rates varied between 30% and 71%.

A systematic characterization of soil/dust ingestion for typical subpopulations in China

An accurate assessment of human exposure to pollutants through the ingestion of dust and/or soil particles depends on a thorough understanding their rate of human ingestion. To this end, we investigated the load and size distribution patterns of dust/soil particles on the hands of three typical subpopulations, including preschoolers, college students, and security guards (outdoor workers). The geometric mean diameter of dust/soil particles on hands was observed to be 38.7 ± 11.2, 40.0 ± 12.1, and 36.8 ± 10.4 μm for preschoolers, college students, and security guards, respectively. The particle size distribution differed between subpopulations: Preschoolers were more exposed to fine particles, whereas security guards were exposed to more coarse particles. The geometric means of dust/soil particle loading on the hands were 0.126, 0.0163, and 0.0377 mg/cm2 for preschoolers, college students, and security guards, respectively. Males had statistically higher dust/soil particle loadings on hands than females, notably for preschoolers and college students; preschoolers with frequent hand contact with the bare ground had higher dust/soil particle loadings compared to those of peers in contact with commercial and residential grounds. The mean total dust/soil particle ingestion rate was estimated to be 245, 19.7, and 33.1 mg/day for preschoolers, college students, and security guards, respectively. Our estimates for college students and security guards are close to the consensus central-tendency values recommended by the U.S. EPA's Exposure Factor Handbook for American adults, whereas the estimates for children are much higher than the upper percentile values recommended for American children.

Characterisation of the risk associated with chronic lifetime exposure to mixture of chemical hazards: case study of trace elements

Risk assessment methodology, mostly commonly used, faces the complexity of the environment. Populations are exposed to multiple sources of chemicals throughout life and the chemical mixtures they are exposed change during time (lifestyle factors, regulatory decisions, etc). The risk assessment needs to consider these dynamics and the evolution of the body with age, in order to refine the exposure assessment to chemicals and to predict the health impact of these exposures. This review highlights the latest methodologies developed to improve risk assessment, especially cor heavy metals. The methodologies aim to better describe the chemical toxicokinetic and toxicodynamic as well as the exposure assessment. Human Biomonitoring (HBM) data give great opportunities to link biomarkers of exposure with an adverse effect. Physiologically-Based Toxicokinetic (PBTK) models are more and more used to simulate the evolution of biomarkers in organisms, considering the external exposures and the physiological evolutions. PBTK models may also be used to determine the routes of exposure or to predict the impacts of schemes of exposure. The major limit is the integration of several chemicals in mixture with common adverse effects and the interactions between them.

Impacts of Indoor Dust Exposure on Human Colonic Cell Viability, Cytotoxicity and Apoptosis

INTRODUCTION

Environmental exposure to indoor dust is known to be associated with myriad health conditions, especially among children. Established routes of exposure include inhalation and non-dietary ingestion, which result in the direct exposure of gastrointestinal epithelia to indoor dust. Despite this, little prior research is available on the impacts of indoor dust on the health of human gastrointestinal tissue.

METHODS

Cultured human colonic (CCD841) cells were exposed for 24 h to standard trace metal dust (TMD) and organic contaminant dust (OD) samples at the following concentrations: 0, 10, 25, 50, 75, 100, 250, and 500 µg/mL. Cell viability was assessed using an MTT assay and protease analysis (glycyl-phenylalanyl-aminofluorocoumarin (GF-AFC)); cytotoxicity was assessed with a lactate dehydrogenase release assay, and apoptosis was assessed using a Caspase-Glo 3/7 activation assay.

RESULTS

TMD and OD decreased cellular metabolic and protease activity and increased apoptosis and biomarkers of cell membrane damage (LDH) in CCD841 human colonic epithelial cells. Patterns appeared to be, in general, dose-dependent, with the highest TMD and OD exposures associated with the largest increases in apoptosis and LDH, as well as with the largest decrements in metabolic and protease activities.

CONCLUSIONS

TMD and OD exposure were associated with markers of reduced viability and increased cytotoxicity and apoptosis in human colonic cells. These findings add important information to the understanding of the physiologic effects of indoor dust exposure on human health. The doses used in our study represent a range of potential exposure levels, and the effects observed at the higher doses may not necessarily occur under typical exposure conditions. The effects of long-term, low-dose exposure to indoor dust are still not fully understood and warrant further investigation. Future research should explore these physiological mechanisms to further our understanding and inform public health interventions.

Environmental and biological monitoring of organochlorine pesticides in the city of Salamanca, Mexico

The former Tekchem Industrial Unit located in the city of Salamanca, Mexico, constitutes an environmental liability in which the presence of high levels of organochlorine pesticides (OCPs) has been reported. In the present study, levels of OCPs were quantified using gas chromatography-mass spectrometry in 52 soil samples and in 88 blood samples from school-age children in the city of Salamanca. A median concentration of 70.6 ng/g (6.93-3299) was obtained for total OCPs in soil, while for the total sum of dichlorodiphenyltrichloroethane (DDT) the value was 49.6 ng/g (6.93-3276). In children, the median level of the total sum of OCPs was 390 ng/g lipid (7.34-14,895), and for the total sum of DDT was 175 ng/g lipid (< LOD-14,802). The OCPs that resulted in highest concentrations in soil were DDT and its metabolites, as well as aldrin and heptachlor epoxide, while in blood the highest levels corresponded to 4,4'-dichlorodiphenyltrichloroethane (4,4'-DDT) and its metabolites, followed by heptachlor and heptachlor epoxide. The spatial distribution of the concentrations of OCPs in soil shows that the facilities of Tekchem may be a significant potential source for the dispersion of these compounds toward the metropolitan area of Salamanca. The results obtained in the present study demonstrate the presence of OCPs in soil and in child population, providing important bases to study the problem from a broader perspective, while reiterating the importance of continuing efforts to generate resolute and precautionary measures with respect to the environmental liability of Tekchem.

Optimization of a method for collecting infant and toddler urine for non-target analysis using cotton pads and commercially available disposable diapers

BACKGROUND

Urine is an abundant and useful medium for measuring biomarkers related to chemical exposures in infants and children. Identification of novel biomarkers is greatly enhanced with non-targeted analysis (NTA), a powerful methodology for broad chemical analysis of environmental and biological specimens. However, collecting urine in non-toilet trained children presents many challenges, and contamination from specimen collection can impact NTA results.

OBJECTIVES

We optimized a caregiver-driven method for collecting urine from infants and children using cotton pads and commercially available disposable diapers for NTA and demonstrate its applicability to various children biomonitoring studies.

METHODS

Experiments were first performed to evaluate the effects of processing method (i.e., centrifuge vs. syringe), storage temperature, and diaper brand on recovery of urine absorbed to cotton pads. Caregivers of 11 children (<2 years) used and retained diapers (with cotton pads) to collect their child's urine for 24 h. Specimens were analyzed via a NTA method implementing an exclusion list of ions related to contamination from collection materials.

RESULTS

Centrifuging cotton pads through a small-pore membrane, compared to a manual syringe method, and storing diapers at 4 °C, compared to room temperature, resulted in larger volumes of recovered sample. This method was successfully implemented to recover urine from cotton pads collected in the field; between 5-9 diapers were collected per child in 24 h, and the total mean volume of urine recovered was 44.7 (range 26.7-71.1) mL. NTA yielded a list of compounds present in urine and/or stool that may hold promise as biomarkers of chemical exposures from a variety of sources.

IMPACT STATEMENT

Infant and children urine is a valuable matrix for studies of the early life exposome, in that numerous biological markers of exposure and outcome can be derived from a single analysis. Depending on the nature of the exposure study, it may be the case that a simple collection method that can be facilitated by caregivers of young children is desirable, especially when time-integrated samples or large volumes of urine are needed. We describe the process for development and results of an optimized method for urine collection and analysis using commercially available diapers and non-target analysis.

Occurrence of 1,3-Diphenylguanidine, 1,3-Di-o-tolylguanidine, and 1,2,3-Triphenylguanidine in Indoor Dust from 11 Countries: Implications for Human Exposure

1,3-Diphenylguanidine (DPG), 1,3-di-o-tolylguanidine (DTG), and 1,2,3-triphenylguanidine (TPG) are synthetic chemicals widely used in rubber and other polymers. Nevertheless, limited information is available on their occurrence in indoor dust. We measured these chemicals in 332 dust samples collected from 11 countries. DPG, DTG, and TPG were found in 100%, 62%, and 76% of the house dust samples, at median concentrations of 140, 2.3, and 0.9 ng/g, respectively. The sum concentrations of DPG and its analogues varied among the countries in the following decreasing order: Japan (median: 1300 ng/g) > Greece (940) > South Korea (560) > Saudi Arabia (440) > the United States (250) > Kuwait (160) > Romania (140) > Vietnam (120) > Colombia (100) > Pakistan (33) > India (26). DPG accounted for ≥87% of the sum concentrations of the three compounds in all countries. DPG, DTG, and TPG exhibited significant correlations (r: 0.35-0.73; p < 0.001). Elevated concentrations of DPG were found in dust from certain microenvironments (e.g., offices and cars). Human exposure to DPG through dust ingestion were in the ranges 0.07-4.40, 0.09-5.20, 0.03-1.70, 0.02-1.04, and 0.01-0.87 ng/kg body weight (BW)/day for infants, toddlers, children, teenagers, and adults, respectively.

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.

Community-Engaged Assessment of Soil Lead Contamination in Atlanta Urban Growing Spaces

Urban agriculture is emerging as a method to improve food security and public health in cities across the United States. However, an increased risk of exposure to heavy metals and metalloids (HMM) exists through interaction with contaminated soil. Community-engaged research (CEnR) is one method that can promote the inclusion of all partners when studying exposures such as HMM in soil. Researchers and community gardeners co-designed this study to measure the concentrations of lead (Pb), using X-Ray Fluorescence (XRF) verified with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in soils from 19 urban agricultural and residential sites in the Westside of Atlanta and three rural sites in Georgia. Seventeen other HMM were measured but not included in this study, because they did not pose risks to the community comparable to elevated Pb levels. Pb concentrations were compared to the Environmental Protection Agency (EPA)'s regional screening levels (RSLs) for residential soil and the University of Georgia (UGA) extension service's low-risk levels (LRLs) for agriculture. Soils from the majority of sites had levels below EPA RSLs for Pb, yet above the UGA LRL. However, soil Pb concentrations were three times higher than the EPA RSL on some sites that contained metal refining waste or slag. Our findings led to direct action by local and federal government agencies to initiate the cleanup of slag residue. Studies involving exposures to communities should engage those affected throughout the process for maximum impact.

A new approach to assess the degree of contamination and determine sources and risks related to PTEs in an urban environment: the case study of Santiago (Chile)

In 2017, a geochemical survey was carried out across the Commune of Santiago, a local administrative unit located at the center of the namesake capital city of Chile, and the concentration of a number of major and trace elements (53 in total) was determined on 121 topsoil samples. Multifractal IDW (MIDW) interpolation method was applied to raw data to generate geochemical baseline maps of 15 potential toxic elements (PTEs); the concentration-area (C-A) plot was applied to MIDW grids to highlight the fractal distribution of geochemical data. Data of PTEs were elaborated to statistically determine local geochemical baselines and to assess the spatial variation of the degree of soil contamination by means of a new method taking into account both the severity of contamination and its complexity. Afterwards, to discriminate the sources of PTEs in soils, a robust Principal Component Analysis (PCA) was applied to data expressed in isometric log-ratio (ilr) coordinates. Based on PCA results, a Sequential Binary Partition (SBP) was also defined and balances were determined to generate contrasts among those elements considered as proxies of specific contamination sources (Urban traffic, productive settlements, etc.). A risk assessment was finally completed to potentially relate contamination sources to their potential effect on public health in the long term. A probabilistic approach, based on Monte Carlo method, was deemed more appropriate to include uncertainty due to spatial variation of geochemical data across the study area. Results showed how the integrated use of multivariate statistics and compositional data analysis gave the authors the chance to both discriminate between main contamination processes characterizing the soil of Santiago and to observe the existence of secondary phenomena that are normally difficult to constrain. Furthermore, it was demonstrated how a probabilistic approach in risk assessment could offer a more reliable view of the complexity of the process considering uncertainty as an integral part of the results.

Contamination Assessment and Potential Human Health Risks of Heavy Metals in Urban Soils from Grand Forks, North Dakota, USA

Heavy metal (HM) pollution of soil is an increasingly serious problem worldwide. The current study assessed the metal levels and ecological and human health risk associated with HMs in Grand Forks urban soils. A total 40 composite surface soil samples were investigated for Mn, Fe, Co, Ni, Cu, Zn, As, Pb, Hg, Cr, Cd and Tl using microwave-assisted HNO3-HCl acid digestion and inductively coupled plasma mass spectrometry (ICP-MS) analysis. The enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), ecological risk and potential ecological risk index were used for ecological risk assessment. The park soils revealed the following decreasing trend for metal levels: Fe > Mn > Zn > Cr > Ni > Cu > Pb > As > Co > Cd > Tl > Hg. Based on mean levels, all the studied HMs except As and Cr were lower than guideline limits set by international agencies. Principal component analysis (PCA) indicated that Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb, Cr and Tl may originate from natural sources, while Hg, Pb, As and Cd may come from anthropogenic/mixed sources. The Igeo results showed that the soil was moderately polluted by As and Cd and, based on EF results, As and Cd exhibited significant enrichment. The contamination factor analysis revealed that Zn and Pb showed moderate contamination, Hg exhibited low to moderate contamination and As and Cd showed high contamination in the soil. Comparatively higher risk was noted for children over adults and, overall, As was the major contributor (>50%), followed by Cr (>13%), in the non-carcinogenic risk assessment. Carcinogenic risk assessment revealed that As and Cr pose significant risks to the populations associated with this urban soil. Lastly, this study showed that the soil was moderately contaminated by As, Cd, Pb and Hg and should be regularly monitored for metal contamination.

Kindergarten indoor dust metal(loid) exposure associates with elevated risk of anemia in children

Exposure to metals and metalloids in indoor dust is associated with adverse health effects in young children, but there is limited evidence for an association with anemia, which is at high risk in children. The aim of this study was to investigate the association between exposure to multiple metal(loid)s in indoor dust in kindergartens and the risk of anemia in children. In 2021, 2165 children from 25 kindergartens in eastern China were included in the study and had their hemoglobin (Hb) measured. Indoor dust samples were collected from the children's kindergartens, and the concentrations of 11 metals and metalloids in the samples were measured using inductively coupled plasma mass spectrometry (ICP-MS). The daily exposure dose (DED) of dust was used to assess the risk of metal(loid) exposure in the children. The results showed that of the 2165 children with available data, 351 (16.2 %) met the WHO definition of anemia. In multiple linear regression and logistic regression analyses, we found that for each quartile of DED increase in Cd inhalation, child Hb levels decreased by 2.703 g/L (95 % CI: -4.055, -1.351), and the risk of anemia increased 1.602-fold (95 % CI: 1.087, 2.360). Mn ingestion was associated with increased odds of anemia [odds ratio (OR) = 1.760 (95 % CI: 1.217, 2.544)]. Interaction analysis indicated that metal(loid)s exposure effects were modified by child sex, age, and body mass index (BMI). Cluster analysis found that children at high risk of metal(loid) exposure in the school environment tended to have lower Hb levels and higher prevalence of anemia compared with those at low risk, although this was not statistically significant. These findings suggest that child school exposure to metal(loid)s in indoor dust is associated with an increased risk of developing anemia in children, modified by child sex, age, and BMI.

Model-based predictions of soil and dust ingestion rates for U.S. adults using the stochastic human exposure and dose simulation soil and dust model

BACKGROUND

Adults can be exposed to chemicals through incidental ingestion of soil and dust, either through hobbies, occupations, or behaviors that increase contact with soil or dust (e.g., cleaning or renovating). However, few data describing these ingestion rates are available.

OBJECTIVE

Our objective was to use the Stochastic Human Exposure and Dose Simulation Soil and Dust (SHEDS-Soil/Dust) model to estimate distributions of soil and dust ingestion rates for adults (≥21 years old) with varying degrees of soil and dust contact.

METHODS

We parameterized SHEDS-Soil/Dust to estimate soil and dust ingestion rates for several categories of adults: adults in the general population; adults with moderate (higher) soil exposure (represented by hobbyists, such as gardeners, with increased soil contact); adults with high soil exposure (represented by occupationally exposed individuals, such as landscapers); and individuals who have high dust exposure (e.g., are in contact with very dusty indoor environments).

RESULTS

Total soil plus dust ingestion for adults in the general population was 7 mg/day. Hobbyists or adults with moderate soil exposure averaged 33 mg/day and occupationally exposed individuals averaged 123 mg/day. Total soil plus dust ingestion for adults in the high dust exposure scenario was 25 mg/day. Results were driven by time spent in contact with soil and, thus, warmer seasons (e.g., summer) were associated with higher ingestion rates than colder seasons (e.g., winter).

SIGNIFICANCE

These results provide modeled estimates of soil and dust ingestion rates for adults for use in decision making using real-world exposure considerations. These modeled estimates suggest that soil and dust ingestion is a potential concern for adults who spend a higher amount of time interacting with either soil or dusty environments.

IMPACT STATEMENT

The parameterization of real-world scenarios within the application of SHEDS-Soil/Dust model to predict soil and dust ingestion rates for adults provides estimates of soil and dust ingestion rates useful for refining population-based risk assessments. These data illuminate drivers of exposure useful for both risk management decisions and designing future studies to improve existing tracer methodologies.

Impact of mining on the metal content of dust in indigenous villages of northern Chile

Indigenous communities from northern Chile have historically been exposed to the impacts of massive copper industrial activities conducted in the region. Some of the communities belonging to the Alto El Loa Indigenous Development Area are located less than 10 km from the "Talabre'' tailings dam, which contains residues from copper production and other metals that can be toxic to human health (e.g., As, Sb, Cd, Mo, Pb). Given the increasing demand of copper production to achieve net-zero emission scenarios and concomitant expansions of the tailings, the exposure to toxic metals is a latent risk to local communities. Despite the impact that copper production could generate on ancestral communities from northern Chile, studies and monitoring are limited and the results are often not made accessible for local communities. Here, we evaluate such risks by characterizing metal concentrations in dust collected from roofs and windows of houses from the Alto El Loa area. Our results showed that As, Sb, Cd, Cu, Mo, Ag, S, and Pb concentrations in these matrices can be connected to local copper mining activities. Additionally, air transport models indicate that high concentrations of toxic elements (As, Sb, and Cd) can be explained by the atmospheric transport of particles from the tailings in a NE direction up to 50 km away. Pollution indices and Health Risk Assessment suggested a highly contaminated region with a health risk for its inhabitants. Our analysis on a local scale seeks to make visible the case of northern Chile as a critical territory where actions should be taken to mitigate the effects of mining in the face of this new scenario of international demand for the raw materials necessary for the transition to a net-zero carbon global society.

Occurrence, exposure and risk assessment of semi-volatile organic compounds in Chinese homes

Indoor semi-volatile organic compounds (SVOCs) can have a significant impact on human health. Previous studies involved the detection of limited classes of indoor SVOCs in different regions of China. However, overall indoor pollution profiles and the associated health risks via multiple exposure pathways remain unclear. High-throughput screening of SVOCs would help clarify the overall indoor pollution status and identify high-risk pollutants. We collected indoor air and dust samples from 35 Chinese homes and investigated the occurrence of a wide range of SVOCs. Ninety-seven SVOCs including phthalate esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), organophosphate esters, alcohols, fatty acids, phenols, etc., were detected in the air (total concentrations: 0.13-48 μg/m³; median: 3.4 μg/m³) and dust (total concentrations: 120-1500 μg/g; median: 490 μg/g) samples. PAEs were the most abundant, accounting for 55.3 ± 28.6% and 43.4 ± 16.9% of the total SVOC concentrations in the air and dust samples respectively. Human exposure and health risks of 34 SVOCs with detection frequencies >10% were assessed based on inhalation, ingestion and dermal absorption of SVOCs from air and dust by infants and adults. In the case of indoor SVOCs with log K_oa < 9, inhalation and dermal contact with air was >90% for adults and >69% for infants. The following five SVOCs in air samples posed significant non-carcinogenic risks and are listed based on their decreasing risk level: dibutyl phthalate > phenanthrene > stearic acid > methyl palmitate > lauryl alcohol. Four PAHs with 2-4 rings posed potential carcinogenic risks, with phenanthrene exceeding the acceptable risk level of 10^-4. The high risks posed by SVOCs were due to inhalation exposure. Therefore, keeping the air concentrations of SVOCs, especially that of PAEs and PAHs under check would greatly benefit human health in indoor environments.

Metallome deregulation and health-related impacts due to long-term exposure to recent volcanic ash deposits: New chemical and isotopic insights

Volcanic ash exposure can lead to significant health risks. Damage to the respiratory and pulmonary systems are the most evident toxic side effects although the causes of these symptoms remain unclear. Conversely, the effects on other organs remain largely under-explored, limiting our understanding of the long-term volcanic ash-related risk at the whole-body scale. The metallome i.e. metal concentrations and isotopic compositions within the body, is suspected to be affected by volcanic ash exposure, having thus the potential for capturing some specificities of ash toxicity. However, the means by and extent to which the metallome is affected at the entire body scale and how the consequent chemical and isotopic deregulations correlate with pathophysiological dysfunctions are currently poorly understood. Here, we adopt a transdisciplinary approach combining high precision chemical analyses (major and trace element concentrations) and CuZn isotope measurements in seven organs and two biological fluids of isogenic mice (C57BL/6) exposed to eruption products from La Soufrière de Guadeloupe (Eastern Carribean), in tandem with biological parameters including physiological and morphological data. Based on principal component analysis, we show that after one month of exposure to volcanic ash deposits, the mice metallome; originally organ-specific and isotopically-typified, is highly disrupted as shown for example by heavy metal accumulation in testis (e.g., Fe, Zn) and Cu, Zn isotopic divergence in liver, intestine and blood. These metallomic variations are correlated with early testicular defects and might reflect the warning signs of premature (entero)hepatic impairments that may seriously affect fertility and favor the emergence of liver diseases after prolonged exposure. Monitoring the temporal evolution of the Cu and Zn isotope compositions seems to be a promising technique to identify the main biological processes and vital functions that are vulnerable to environmental volcanogenic pollutants although this will require further validation on human subjects.

Estimation of Children's Soil and Dust Ingestion Rates and Health Risk at E-Waste Dismantling Area

Due to environmental health concerns, exposure to heavy metals and related adverse effects in electronic waste (e-waste) dismantling areas have attracted considerable interest in the recent years. However, little information is available about the Soil/Dust Ingestion Rates (SIR) of heavy metals for children living in such sites. This study estimated the soil ingestion of 66 children from e-waste disassembly areas by collecting and analyzing selected tracer elements in matched samples of their consumed food, feces, and urine, as well as soil samples from their play areas. The concentrations of tracer elements (including Al, Ba, Ce, Mn, Sc, Ti, Y, and V) in these samples were analyzed. The SIR was estimated to be 148.3 mg/day (median) and 383.3 mg/day (95th percentile) based on the Best Tracer Method (BTM). These values are somewhat higher than those observed in America, Canada, and other parts of China. Health risk assessments showed that Cr presented the greatest carcinogenic risk, at more than 10^-6 in this typical polluted area, while As was second. These findings provide important insights into the exposure risks of heavy metals in e-waste dismantling sites and emphasize the health risk caused by Cr and As.

Model based prediction of age-specific soil and dust ingestion rates for children

BACKGROUND

Soil and dust ingestion can be a primary route of environmental exposures. Studies have shown that young children are more vulnerable to incidental soil and dust ingestion. However, available data to develop soil and dust ingestion rates for some child-specific age groups are either lacking or uncertain.

OBJECTIVE

Our objective was to use the Stochastic Human Exposure and Dose Simulation Soil and Dust (SHEDS-Soil/Dust) model to estimate distributions of soil and dust ingestion rates for ten age ranges from infancy to late adolescents (birth to 21 years).

METHODS

We developed approaches for modeling age groups previously not studied, including a new exposure scenario for infants to capture exposures to indoor dust via pacifier use and accounting for use of blankets that act as a barrier to soil and dust exposure.

RESULTS

Overall mean soil and dust ingestion rates ranged from ~35 mg/day (infants, 0-<6 m) to ~60 mg/day (toddlers and young children, 6m-<11 yr) and were considerably lower (about 20 mg/day) for teenagers and late adolescents (16-<21 y). The pacifier use scenario contributed about 20 mg/day to the median dust ingestion rate for young infants. Except for the infant age groups, seasonal analysis showed that the modeled estimates of average summer mean daily total soil plus dust ingestion rates were about 50% higher than the values predicted for the winter months. Pacifier use factors and carpet dust loading values were drivers of exposure for infants and younger children. For older children, influential variables included carpet dust loading, soil adherence, and factors that capture the frequency and intensity of hand-to-mouth behaviors.

SIGNIFICANCE

These results provide modeled estimates of children's soil and dust ingestion rates for use in decision making using real-world exposure considerations.

IMPACT STATEMENT

The parameterization of scenarios to capture infant soil and dust ingestion and the application of SHEDS-Soil/Dust to a broader age range of children provides additional estimates of soil and dust ingestion rates that are useful in refining population-based risk assessments. These data illuminate drivers of exposure that are useful to both risk management applications and for designing future studies that improve upon existing tracer methodologies.

Is hand-to-mouth contact the main pathway of children's soil and dust intake?

Children (n = 240) between the ages of 2 and 17 years were randomly selected from three cities in China. The total amount of soil and dust (SD) on their hands was measured and ranged from 3.50-187.39 mg (median = 19.49 mg). We screened for seven elements (Ce, V, Y, Al, Ba, Sc, and Mn), and Ce levels were used to calculate hand SD by variability and soil elements. The main factors affecting SD amount were location and age group, as identified using a conditional inference tree. Hand SD and the hand SD intake rate were highest in Gansu Province, followed by Guangdong and Hubei provinces, respectively. Hand SD and the hand SD intake rate were highest among children in primary school, followed by kindergarten and secondary school, respectively. The hand SD intake rate of the three typical areas was 11.9 mg/d, which was about 26.6% of the children's soil intake rate (44.8 mg/d), indicating that hand-to-mouth contact is not the main route for children's soil intake in the three areas of China.

Source apportionment and health risk assessment for potentially toxic elements in size-fractionated road dust in Busan Metropolitan City, Korea

Potentially toxic elements' (PTEs; V, Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Pb, and Hg) pollution level was investigated in size-fractionated road dust in Busan Metropolitan City. Health risks to humans (adult and children) were also evaluated in fine particle fraction (< 63 μm) of road dust. PTE concentrations in the fine particles (< 63 μm) were ranked as follows (unit: mg/kg): Zn (2511) > Cu (559) > Cr (531) > Pb (385) > Ni (139) > V (83.8) > Sb (31.6) > Co (21.6) > As (17.2) > Cd (4.1) > Hg (0.38). The PTE concentrations in fine particles (< 63 μm) were significantly higher than those in coarse particles except for V, Co, and As. The mean PTE loadings of fine particle fraction (< 63 μm; 233 mg/m2) in road dust were up to 4.5 times higher than other particle fractions. Igeo values of Sb were higher than 5 except for > 1000-μm fraction, indicating extremely polluted status. PCA results and elemental ratios indicated that most of the PTEs in road dust were derived from non-exhaust traffic-related sources such as brake pads and tires. Cr, Pb, and Sb had higher HI values than other metals for both adults and children. Sampling sites of heavy traffic and industrial areas showed that the carcinogenic risk exceeded the maximum threshold level (10 - 4). Especially in children, the mean carcinogenic risk (ingestion pathway) of As (6.8 × 10 - 4) Cd (2.0 × 10 - 4), and Ni (4.1 × 10 - 4) exceeded the maximum threshold level, indicating that continuous exposure to road dust may pose a high cancer risk to children. Therefore, continuous monitoring and management of these metals are needed to protect human health and the urban environment.

Heavy metal pollution of soils and risk assessment in Houston, Texas following Hurricane Harvey

In August 2017, after Hurricane Harvey made landfall, almost 52 inches of rain fell during a three-day period along the Gulf Coast Region of Texas, including Harris County, where Houston is located. Harris County was heavily impacted with over 177,000 homes and buildings (approximately 12 percent of all buildings in the county) experiencing flooding. The objective of this study was to measure 13 heavy metals in soil in residential areas and to assess cancer and non-cancer risk for children and adults after floodwaters receded. Between September and November 2017, we collected 174 surface soil samples in 10 communities, which were classified as "High Environmental Impact" or "Low Environmental Impact" communities, based on a composite metric of six environmental parameters. A second campaign was conducted between May 2019 and July 2019 when additional 204 soil samples were collected. Concentrations of metals at both sampling campaigns were higher in High Environmental Impact communities than in Low Environmental Impact communities and there was little change in metal levels between the two sampling periods. The Pollution Indices of lead (Pb), zinc, copper, nickel, and manganese in High Environmental Impact communities were significantly higher than those in Low Environmental Impact communities. Further, cancer risk estimates in three communities for arsenic through soil ingestion were greater than 1 in 1,000,000. Although average soil Pb was lower than the benchmark of the United States Environmental Protection Agency, the hazard indices for non-cancer outcomes in three communities, mostly attributed to Pb, were greater than 1. Health risk estimates for children living in these communities were greater than those for adults.

Health Risk Assessment for the Residential Area Adjacent to a Former Chemical Plant

A health risk assessment was carried out for the residents of Łęgnowo-Wieś settlement adjacent to a former Zachem Chemical Plant, Bydgoszcz, Poland. Due to the unique Zachem site history and contamination profile, an innovative strategy for soil sampling and contaminant selection was applied. The novelty in the developed strategy consisted of selecting substances for the health risk assessment, taking into consideration the location and boundaries of the groundwater contamination plumes in relation to contamination sources. This allowed limiting the number of the analysed contaminants. The risk assessment focused on the surface soil of a residential area, which was divided into 20 sampling sectors and 6 backyards with wells from which water was used for watering edible plants. A total of 80 inorganic and organic substances were determined, including metals, phenol, aniline, BTEX, diphenyl sulphone, chloroaniline, epichlorohydrin, hydroxybiphenyl, nitrobenzene, octylphenols, toluenediamine, toluidine, 16 polycyclic aromatic hydrocarbons, tetrachloroethylene and trichloroethylene. For the health risk assessment, the United States Environmental Protection Agency’s deterministic method was applied. This applies conservative assumptions to obtain risk estimates protective for most of the potential receptors. Three exposure pathways were analysed: (1) incidental soil ingestion, (2) dermal contact with soil and (3) inhalation of fugitive soil particles and volatiles. In all sampling sectors and backyards, the total non-cancer risks (hazard index) were significantly lower than the acceptable level of 1. The acceptable cancer risk level for the single carcinogen of 1 × 10⁻⁵ was only insignificantly exceeded in the case of benzo(a)pyrene in three sectors and one backyard. The total cancer risks were lower than the acceptable level of 1 × 10⁻⁴ in all sampling sectors and all backyards. The findings show that the soil in the entire residential area is safe for the residents’ health and no remedial actions are required. However, since not all possible exposure pathways were analysed in this study, further research focused on assessing the health risk resulting from the consumption of locally grown food is strongly recommended.

Heavy Metals in Soil and Sand from Playgrounds of Çanakkale City (Turkey), and Related Health Risks for Children

Children spend most of their time in playgrounds and, in parallel, constitute the social group most sensitive to contaminants. Here, we present the results of a comparative study of heavy-metal contents between soils and sand from sandboxes obtained from playgrounds of Çanakkale city. Average contents of soils followed the order of iron (Fe) (12,901 mg kg−1) > manganese (Mn) (475 mg kg−1) > zinc (Zn) (58 mg kg−1) > copper (Cu) (28 mg kg−1) > nickel (Ni), chromium (Cr) (21 mg kg−1) > lead (Pb) (18 mg kg−1). Sand had lower contents, however, due to the reduction of particles size through prolonged use, and accumulation of Fe/Mn (oxyhydr)oxides on sand grains tended to diminish the differences between soils and sand. Through chemometric analysis, Cr and Ni were found to have a lithogenic origin, while the rest of metals were related to anthropogenic activities. Spatially, heavy-metal contents followed the pattern of the city’s sprawl. Risk estimates on children’s health showed that ingestion was the most important exposure route, followed by dermal contact and inhalation. Exposure of children to sand was of similar importance to that of soils. These findings are significant, as the contamination of sand has not yet received much attention compared to the soil of playgrounds.

Emerging investigator series: the role of chemical properties in human exposure to environmental chemicals

One of the ultimate goals of environmental exposure science is to mechanistically understand how chemical properties and human behavior interactively determine human exposure to the wide spectrum of chemicals present in the environment. This comprehensive review assembles state-of-the-art knowledge of the role of partitioning, dissociation, mass transfer, and reactive properties in human contact with and absorption of organic chemicals via oral, dermal, and respiratory routes. Existing studies have revealed that chemicals with different properties vary greatly in mass distribution and occurrence among multiple exposure media, resulting in distinct patterns of human intake from the environment. On the other hand, these chemicals encounter different levels of resistance in the passage of intestinal, dermal, and pulmonary absorption barriers and demonstrate different levels of bioavailability, due to the selectivity of biochemical, anatomical and physiological structures of these absorption barriers. Moving forward, the research community needs to gain more in-depth mechanistic insights into the complex processes in human exposure, advance the technique to better characterize and predict chemical properties, generate and leverage experimental data for a more diverse range of chemicals, and describe better the interactions between chemical properties and human behavior.

Estimation of Soil and Dust Ingestion Rates from the Stochastic Human Exposure and Dose Simulation Soil and Dust Model for Children in Taiwan

This study focuses on estimating the probabilistic soil and dust ingestion rates for children under 3 years old by the Stochastic Human Exposure and Dose Simulation Soil and Dust (SHEDS-S/D) model developed by the U.S. Environmental Protection Agency. The health risk of children's exposure to heavy metals through soil and dust ingestion and dermal absorption was then assessed in three exposure scenarios. In the exposure scenario of direct contact with soil, the average soil and dust ingestion rates for children aged 24 to 36 months were 90.7 and 29.8 mg day^-1 in the sand and clay groups, respectively. Hand-to-mouth soil ingestion was identified as the main contributor to soil and dust ingestion rates, followed by hand-to-mouth dust ingestion and object-to-mouth dust ingestion. The soil-to-skin adherence factor was the most influential factor increasing the soil and dust ingestion rate based on a sensitivity analysis in the SHEDS-S/D model. Furthermore, the modeled soil and dust ingestion rates based on the SHEDS-S/D model were coincident with results calculated by the tracer element method. Our estimates highlight the soil ingestion rate as the key parameter increasing the risk for children, while a higher frequency of hand washing could potentially reduce the risk.

A Systematic Framework for Collecting Site-Specific Sampling and Survey Data to Support Analyses of Health Impacts from Land-Based Pollution in Low- and Middle-Income Countries

The rise of small-scale and localized economic activities in low- and middle-income countries (LMICs) has led to increased exposures to contaminants associated with these processes and the potential for resulting adverse health effects in exposed communities. Risk assessment is the process of building models to predict the probability of adverse outcomes based on concentration-response functions and exposure scenarios for individual contaminants, while epidemiology uses statistical methods to explore associations between potential exposures and observed health outcomes. Neither approach by itself is practical or sufficient for evaluating the magnitude of exposures and health impacts associated with land-based pollution in LMICs. Here we propose a more pragmatic framework for designing representative studies, including uniform sampling guidelines and household surveys, that draws from both methodologies to better support community health impact analyses associated with land-based pollution sources in LMICs. Our primary goal is to explicitly link environmental contamination from land-based pollution associated with specific localized economic activities to community exposures and health outcomes at the household level. The proposed framework was applied to the following three types of industries that are now widespread in many LMICs: artisanal scale gold mining (ASGM), used lead-acid battery recycling (ULAB), and small tanning facilities. For each activity, we develop a generalized conceptual site model (CSM) that describes qualitative linkages from chemical releases or discharges, environmental fate and transport mechanisms, exposure pathways and routes, populations at risk, and health outcomes. This upfront information, which is often overlooked, is essential for delineating the contaminant zone of influence in a community and identifying relevant households for study. We also recommend cost-effective methods for use in LMICs related to environmental sampling, biological monitoring, survey questionnaires, and health outcome measurements at contaminated and unexposed reference sites. Future study designs based on this framework will facilitate consistent, comparable, and standardized community exposure, risk, and health impact assessments for land-based pollution in LMICs. The results of these studies can also support economic burden analyses and risk management decision-making around site cleanup, risk mitigation, and public health education.

Soil ingestion among young children in rural Bangladesh

Ingestion of soil and dust is a pathway of children's exposure to several environmental contaminants, including lead, pesticides, and fecal contamination. Empirically based estimates of central tendency for soil consumption by children in high-income countries range from 9 to 135 dry mg/day. Using a Monte Carlo simulation, we modeled the mass of soil directly and indirectly ingested per day by rural Bangladeshi children and identified the parameters that influence the mass ingested. We combined data from observations of direct and indirect ingestion among children with measurements of soil mass on the children's hands, mother's hands, and objects to quantify soil ingestion/day. Estimated geometric mean soil ingestion was 162 dry mg/day for children 3-5 months, 224 dry mg/day for children 6-11 months, 234 dry mg/day for children 12-23 months, 168 dry mg/day for children 24-35 months, and 178 dry mg/day for children 36-47 months old. Across all age groups, children placing their hands in their mouths accounted for 46-78% of total ingestion and mouthing objects contributed 8-12%. Direct ingestion of soil accounted for nearly 40% of soil ingested among children 6-23 months old. Sensitivity analyses identified that the parameters most affecting the estimates were the load of soil on the child's hand, the frequency of hand-to-mouth contacts while not eating, and, for children 6-23 months old, the frequency of direct soil ingestion. In a rural, low-income setting, children's soil consumption was substantially more than the estimates for children in high-income countries. Further characterizing soil ingestion of children in low-income contexts would improve assessments of the risks they face from soil-associated contaminants.

A quest to identify suitable organic tracers for estimating children's dust ingestion rates

Chemical exposure via dust ingestion is of great interest to researchers and regulators because children are exposed to dust through their daily activities, and as a result, to the many chemicals contained within dust. Our goal was to develop a workflow to identify and rank organic chemicals that could be used as tracers to calculate children's dust ingestion rates. We proposed a set of criteria for a chemical to be considered a promising tracer. The best tracers must be (1) ubiquitous in dust, (2) unique to dust, (3) detectable as biomarkers in accessible biological samples, and (4) have available or obtainable ADME information for biomarker-based exposure reconstruction. To identify compounds meeting these four criteria, we developed a workflow that encompasses non-targeted analysis approaches, literature and database searching, and multimedia modeling. We then implemented an ad hoc grading system and ranked candidate chemicals based on fulfillment of our criteria (using one small, publicly available dataset to show proof of concept). Initially, five chemicals (1,3-diphenylguanidine, leucine, piperine, 6:2/8:2 fluorotelomer phosphate diester, 6:2 fluorotelomer phosphate diester) appeared to satisfy many of our criteria. However, a rigorous manual investigation raised many questions about the applicability of these chemicals as tracers. Based on the results of this initial pilot study, no individual compounds can be unequivocally considered suitable tracers for calculating dust ingestion rates. Future work must therefore consider larger datasets, generated from broader measurement studies and literature searches, as well as refinements to selection criteria, to identify robust and defensible tracer compounds.

Soil-skin adherence measures from hand press trials in a Gulf study of exposures

Marine oil spills and the resulting environmental contamination is common along coastal areas; however, information is lacking about the safety of impacted beaches for public use, especially for the most vulnerable population: children. One route of exposure for children at oil impacted beaches is through contact with sands. The purpose of this study was to evaluate beach sand skin adherence for children under the age of seven. Each of 122 children participated in a hand press trial conducted at one of four different U.S. beaches (two in Miami, FL, and two in Galveston, TX USA). During the hand press trials, hand conditions of the children were randomized (dry, wet, or with sunscreen), and soil adherence (mass of sand per palmar surface area of the hand) and the maximum pressure applied (force applied per area of hand) was measured and calculated. Each child was instructed to press their hands on a soil laden tray for 5 s and pressure of contact was measured using a scale. Results (n = 98) showed that the average soil adherence for both palmar hands across the four beaches ranged from 0.200 to 234 mg/cm² with an average of 35.7 mg/cm², with boys (40.4 mg/cm²) showing slightly higher means than girls (31.7 mg/cm²), but these differences were not significant even after adjusting for age. Among the three conditions evaluated, the highest loading was measured for children with wet hands (mean 65.3 mg/cm²), followed by dry hands (mean 24.5 mg/cm²). Sunscreen hands (mean 23.2 mg/cm²) had the lowest loadings. The pressure of contact ranged from 0.180 to 1.69 psi and varied by age groups and by height and weight, where pressure of contact did not have a significant influence on soil adherence. The average adhered sand grain size and average ambient sand grain size both had a statistically significant impact on hand soil adherence. Overall results from this study can be utilized in exposure and risk assessment models to evaluate the possible health impacts from contaminants found in beach sands.

Direct Transfer of Phthalate and Alternative Plasticizers from Indoor Source Products to Dust: Laboratory Measurements and Predictive Modeling

Phthalate and alternative plasticizers are semivolatile organic compounds (SVOCs) and among the most abundant indoor pollutants. Although ingestion of dust is one of the major exposure pathways to them, migration knowledge from source products to indoor dust is still limited. Systematic chamber measurements were conducted to investigate the direct transfer of these SVOCs between source products and dust in contact with the source. Substantial direct source-to-dust transfer of SVOCs was observed for all tests. The concentration of bis(2-ethylhexyl)phthalate in dust was 12 times higher than the pre-experimental level after only two days of source-dust contact. A mechanistic model was developed to predict the direct transfer process, and a reasonable agreement between model predictions and measurements was achieved. The octanol/air partition coefficient (K_oa) of SVOCs, the emission parameter of the source product (y₀), and the characteristics of the dust layer (i.e., porosity and thickness) control the transfer, affecting the SVOC concentration in dust, the kinetics of direct transfer, or both. Dust mass loading has a significant influence on the transfer, while relative humidity only has a limited effect. The findings suggest that minimizing the use of SVOC-containing products and house vacuuming are effective intervention strategies to reduce young children's exposure to SVOCs.

Trace elements in two particle size fractions of urban soils collected from playgrounds in Bratislava (Slovakia)

Today, it is proven that the contaminated urban soils are hazardous for the human health. Soil substrates of playgrounds call for special research as they are places where children are directly exposed to soil contaminants. Therefore, the objective of this work was to measure the pseudo-total contents and bioaccessibility of several metals and metalloids (As, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sn, V, Zn) in two grain sizes (< 150 μm and < 50 μm) of playground soils in Bratislava city (the capital of Slovakia). The content of metal(loid)s in the soils was controlled by a number of factors, with their increased contents (above 75% percentile or higher) at sites influenced by point sources of pollution (industry and agriculture) or at old sites located in the city centre. Cobalt, Cr, Fe, Mn, Ni and V had relatively uniform contents in soils compared to the other elements. As regression modelling with a categorical variable confirmed, the age of urban areas influenced the accumulation of As, Bi, Cd, Cu, Hg, Pb, Sb and Sn in playground soils. Exploratory statistical techniques with compositionally transformed data (principal component analysis, cluster analysis and construction of symmetric coordinates for correlation analysis) divided trace elements into the two main groupings, Co, Cr, Fe, Mn, Ni, V and Bi, Cd, Cu, Hg, Pb, Sb, Sn, Zn. Median concentrations of the elements in smaller soil grains (< 50 μm) were significantly higher than in coarser grains (< 150 μm). Cobalt, Cu, Mn, Pb, Sn and Zn had significantly higher bioaccessible proportions (% of the pseudo-total content) in < 50 μm soil size than in < 150 μm; however, the same order of bioaccessibility was achieved in both grain sizes. The highest bioaccessibility had Cd, Cu, Pb and Zn (~ 40% and more), followed by Co, As, Mn, Sb (18-27%), Hg, Ni, Sn (10-12%) and finally Cr, Fe and V (less than 4%). The hazard index and carcinogenic risk values were higher in < 50 μm than in < 150 μm and significantly decreased in the two soil sizes when the bioaccessibility results were included in the health hazard calculation.

Developmental Origins of Health and Disease: Impact of environmental dust exposure in modulating microbiome and its association with non-communicable diseases

Non-communicable diseases (NCDs) including obesity, diabetes, and allergy are chronic, multi-factorial conditions that are affected by both genetic and environmental factors. Over the last decade, the microbiome has emerged as a possible contributor to the pathogenesis of NCDs. Microbiome profiles were altered in patients with NCDs, and shift in microbial communities was associated with improvement in these health conditions. Since the genetic component of these diseases cannot be altered, the ability to manipulate the microbiome holds great promise for design of novel therapies in the prevention and treatment of NCDs. Together, the Developmental Origins of Health and Disease concept and the microbial hypothesis propose that early life exposure to environmental stimuli will alter the development and composition of the human microbiome, resulting in health consequences. Recent studies indicated that the environment we are exposed to in early life is instrumental in shaping robust immune development, possibly through modulation of the human microbiome (skin, airway, and gut). Despite much research into human microbiome, the origin of their constituent microbiota remains unclear. Dust (also known as particulate matter) is a key determinant of poor air quality in the modern urban environment. It is ubiquitous and serves as a major source and reservoir of microbial communities that modulates the human microbiome, contributing to health and disease. There are evidence that reported significant associations between environmental dust and NCDs. In this review, we will focus on the impact of dust exposure in shaping the human microbiome and its possible contribution to the development of NCDs.

Combining data from heterogeneous surveys for aggregate exposure: Application to children exposure to lead in France

To assess human health risks related to the environment, it is necessary to aggregate exposure from multiple sources. The objective of this paper was to propose a relevant approach to combine data from heterogeneous populations and methodologies. Five different methods based on Monte-Carlo simulations were tested and compared. Differences were: taking into account or not stratification variable, timeline to assign exposure factors and concentration and way to account for concentration correlations. The methods were applied to estimate lead exposure from food, dust, soil, air, and tap water or French children aged between six months and three years old. Comparing results' uncertainty, it is recommended to 1) select a reference population representative of the target population, 2) select stratification variables to combine surveys, and 3) simulate a new population by randomly sampling individuals in the reference population and simultaneously assigning human exposure factors and environmental concentrations from other surveys in integrating correlations (MC1S). No difference was observed when taking into account correlations using vectors of determinist data from one survey or rank of correlations with the Iman-Conover method. Regardless the methods used to combine data, dust was the main exposure source, followed by soil and in a less extent by food. Exposures from air and tap water were found to be insignificant for most children.

Mechanisms of children's soil exposure

Pollution is a concerning and highly studied area, especially in the arena of children's health. The focus of this concern, however, is typically limited to air and water pollution, leaving an important source under-studied and out of the concern of the general public. Soil pollution provides a unique threat to children's health, due to their increased exposure and susceptibility to its contaminants. The microbiome of a child is developed prior to birth and continues to evolve over their lifetime with each encounter to the outside world. The environment a child inhabits directly affects their microbiome and their overall health, and through interactions with contaminated soil, a child can accumulate adverse health outcomes. The aim of this article is to summarize the methods by which soil becomes contaminated and how children become exposed to the resulting toxicants.

Bioavailability of phthalate and DINCH® plasticizers, after oral administration of dust to piglets

For decades, phthalates have been widely used as plasticizers in a large number of consumer products, leading to a complex exposure to humans via ingestion, inhalation or dermal uptake. Children may have a higher unintended dust intake per day compared to adults. Therefore, dust intake of children could pose a relevant exposure and subsequently a potential health risk. The aim of this study was to determine the relative bioavailability of certain phthalates, such as di(2-ethylhexyl) phthalate (DEHP), di-isononyl phthalate (DINP) and the non-phthalate plasticizer diisononyl 1,2-cyclohexanedicarboxylic acid (DINCH^®, Hexamoll^®), after ingestion of dust. Seven 5-week-old male piglets were fed five different dust samples collected from daycare centers. Overall, 0.43 g to 0.83 g of dust sieved to 63 μm were administered orally. The piglets' urine was collected over a period of 38 h. The excreted metabolites were quantified using an LC-MS/MS method. The mean uptake rates of the applied doses for DEHP, DINP, and DINCH^® were 43% ± 11%, 47% ± 26%, and 9% ± 3.5%, respectively. The metabolites of DEHP and DINP showed maximum concentrations in urine after three to five hours, whereas the metabolites of DINCH^®, reached maximum concentrations 24 h post-dose. The oral bioavailability of the investigated plasticizers was higher compared to the bioaccessibility reported from in vitro digestion tests. Furthermore, the bioavailability of DEHP did not vary substantially between the dust samples, whereas a dose-dependent saturation process for DINP was observed. In addition to other intake pathways, dust could be a source of plasticizers in children using the recent intake rates for dust ingestion.

Unprecedentedly High Dust Ingestion Estimates for the General Population in a Mining District of DR Congo

The mining of metals in low income countries is often associated with high exposure to dust that contributes to metal exposure. Here, dust ingestion estimates were made from fecal excretion of inert tracers with corrections for dietary contribution. The study took place in the cobalt mining area of Lubumbashi (DR Congo) and involved 120 nonoccupationally exposed participants in the dry season, with 51 of these being repeated in the rainy season. For each participant, duplicate meals (0-96 h), feces (24-120 h), and indoor/outdoor dust (<250 μm) were collected. The dust ingestion estimates (g day^-1) were derived from Nb, Ti, and V as best tracers and were 0.28 (geometric mean), 3.3 (mean), and 13 (P95); these values are almost a factor 10 above currently accepted estimates for the general population in high income countries. Mean dust ingestion in the dry season was twice that of the rainy season, and the P95s were significantly higher in children (3-15 years) than in male adults and toddlers; geophagy (>40 g day^-1) was suspected in three individuals. These data explain the previously reported extreme cobalt exposures in children and support the need to manage dust in the metal mining operations.

Soil mutagenicity - Effects of acidification and organic pollutants in urban/industrial areas

This study aimed to analyze (i) the effect of different acid extractions, simulating changes in the background pH of rain on the availability of soil mutagenic compounds, (ii) the presence of organic compounds in soil and (iii) evaluation of the effects of soil sieving on the samples mutagenicity. Surface soil samples were collected at urban and industrial areas and assessed as total grain size composition (Total Soil) and in sieved fraction <0.5 mm (Soil <0.5 mm), through acid extracts with pH simulating those found in local rainfall. Metals were quantified in extracts and soils in natura. Organic extracts were analyzed for PAH content. Salmonella/microsome mutagenicity assay (TA98 strain) was used, in the presence/absence of exogenous metabolism. Nitro-sensitive strains YG1021 and YG1024 were used in the organic extracts. Results showed different mutagenic responses in total soils and in soil <0.5 mm. Soil extraction at pH 3.6 presented higher toxicity, greater variety and concentration of metals. Extraction at pH 5.3 improved mutagenic detection. Thus, local rainfall may be an environmental contamination route, with additional risk of releasing toxic substances during acid precipitation events.

A soil ingestion pilot study for teenage children in China

Soil ingestion by people is an important route of exposure to environmental contaminants. Studies on soil ingestion using tracer mass-balance method are mainly for young children and adults, scarcely for teenagers. In such case, the soil ingestion rate for teenagers recommended by regulators is generally identical to that of adults based on one activity pattern modeling study. However, teenagers are expected to have different soil ingestion exposure via ingestion pathway due to different activity patterns and exposure scenarios. We conducted a pilot study on soil ingestion in 30 teenage children aged 12.0-16.5 years from Hubei Province of China, using the best tracer method, with the results compared with previous soil ingestion studies. The estimated mean and median soil ingestion rates for teenagers in this study based on the best five tracers (Al, Ce, Sc, V, and Y) were 45.2 mg d^-1 and 44.8 mg d^-1 respectively, with the 95% confidence interval of the mean value ranging from 28.0 mg d^-1 to 50.9 mg d^-1. These soil ingestion rate estimates were slightly higher than the recommended values for adults by U.S. EPA, but lower than those for Chinese younger children observed in the other similar study. The result in this study is important to access the health risk resulting from exposure to toxic substances in soil via direct soil ingestion pathway by teenagers in China as well as other countries.

Estimates of Soil Ingestion in a Population of Chinese Children

BACKGROUND

China's soil pollution poses serious health risks. However, data regarding the soil ingestion rate (SIR) of the Chinese population, which is critical to assessing associated health risks, are lacking.

OBJECTIVES

We estimated soil ingestion of 177 Chinese children from Guangdong, Hubei, and Gansu Provinces.

METHODS

We conducted this investigation by employing a tracer mass-balance method. We collected a duplicate of all food consumed and all feces and urine excreted on 1 d (n=153) and over 3 consecutive d (n=24), as well as soil samples from play areas and drinking-water samples. We analyzed concentrations of the tracer elements Al, Ba, Ce, Mn, Sc, Ti, V, and Y in these samples using ICP-AES and ICP-MS and estimated the SIR for each subject.

RESULTS

The estimated SIR data based on each tracer element were characterized by a skewed distribution, as well as higher inter-tracer and inter-subject variation, with several outliers. After removing the outliers, daily SIR median (range) values in milligrams per day were Al, 27.8 (−42.0 to 257.3); Ba, 36.5 (−230.3 to 412.7); Ce, 35.3 (−21.2 to 225.8); Mn, 146.6 (−1259.4 to 1827.7); Sc, 54.8 (−4.5 to 292.0); Ti, 36.7 (−233.7 to 687.0); V, 92.1 (10.4 to 308.0); and Y, 59.1 (−18.4 to 283.0). Daily SIR median/95th percentile (range) values based on the best tracer method (BTM) were 51.7/216.6 (−9.5 to 297.6) mg/d.

CONCLUSIONS

Based on the BTM, recommended SIR values for the general population of Chinese children (2.5 to 12 years old) are 52 mg/d for the central tendency and 217 mg/d for the upper percentile. We did not differentiate between outside soil and indoor dust. Considering the lower concentration of tracer elements in indoor dust than outside soil, actual soil and dust ingestion rates could be higher. https://doi.org/10.1289/EHP930.

Seasonal and occupational trends of five organophosphate pesticides in house dust

Since 1998, the University of Washington's Center for Child Environmental Health Risks Research has followed a community-based participatory research strategy in the Lower Yakima Valley of Washington State to assess pesticide exposure among families of Hispanic farmworkers. As a part of this longitudinal study, house dust samples were collected from both farmworker and non-farmworker households, across three agricultural seasons (thinning, harvest and non-spray). The household dust samples were analyzed for five organophosphate pesticides: azinphos-methyl, phosmet, malathion, diazinon, and chlorpyrifos. Organophosphate pesticide levels in house dust were generally reflective of annual use rates and varied by occupational status and agricultural season. Overall, organophosphate pesticide concentrations were higher in the thinning and harvest seasons than in the non-spray season. Azinphos-methyl was found in the highest concentrations across all seasons and occupations. Farmworker house dust had between 5- and 9-fold higher concentrations of azinphos-methyl than non-farmworker house dust. Phosmet was found in 5-7-fold higher concentrations in farmworker house dust relative to non-farmworker house dust. Malathion and chlorpyriphos concentrations in farmworker house dust ranged between 1.8- and 9.8-fold higher than non-farmworker house dust. Diazinon showed a defined seasonal pattern that peaked in the harvest season and did not significantly differ between farmworker and non-farmworker house dust. The observed occupational differences in four out of five of the pesticide residues measured provides evidence supporting an occupational take home pathway, in which workers may bring pesticides home on their skin or clothing. Further, these results demonstrate the ability of dust samples to inform the episodic nature of organophosphate pesticide exposures and the need to collect multiple samples for complete characterization of exposure potential.

Soil ingestion rates for children under 3 years old in Taiwan

Soil and dust ingestion rates by children are among the most critical exposure factors in determining risks to children from exposures to environmental contaminants in soil and dust. We believe this is the first published soil ingestion study for children in Taiwan using tracer element methodology. In this study, 66 children under 3 years of age were enrolled from Taiwan. Three days of fecal samples and a 24-h duplicate food sample were collected. The soil and household dust samples were also collected from children's homes. Soil ingestion rates were estimated based on silicon (Si) and titanium (Ti). The average soil ingestion rates were 9.6±19.2 mg/day based on Si as a tracer. The estimated soil ingestion rates based on Si did not have statistically significant differences by children's age and gender, although the average soil ingestion rates clearly increased as a function of children's age category. The estimated soil ingestion rates based on Si was significantly and positively correlated with the sum of indoor and outdoor hand-to-mouth frequency rates. The average soil ingestion rates based on Si were generally lower than the results from previous studies for the US children. Ti may not be a suitable tracer for estimating soil ingestion rates in Taiwan because the Ti dioxide is a common additive in food. To the best of our knowledge, this is the first study that investigated the correlations between soil ingestion rates and mouthing behaviors in Taiwan or other parts of Asia. It is also the first study that could compare available soil ingestion data from different countries and/or different cultures. The hand-to-mouth frequency and health habits are important to estimate the soil ingestion exposure for children. The results in this study are particularly important when assessing children's exposure and potential health risk from nearby contaminated soils in Taiwan.

Passive exposure to agricultural pesticides and risk of childhood leukemia in an Italian community

BACKGROUND

Exposure to pesticides has been suggested as a risk factor for childhood leukemia, but definitive evidence on this relation and the specific pesticides involved is still not clear.

OBJECTIVE

We carried out a population-based case-control study in a Northern Italy community to assess the possible relation between passive exposure to agricultural pesticides and risk of acute childhood leukemia.

METHODS

We assessed passive pesticide exposure of 111 childhood leukemia cases and 444 matched controls by determining density and type of agricultural land use within a 100-m radius buffer around children's homes. We focused on four common crop types, arable, orchard, vineyard and vegetable, characterized by the use of specific pesticides that are potentially involved in childhood induced leukemia. The use of these pesticides was validated within the present study. We computed the odds ratios (OR) of the disease and their 95% confidence intervals (CI) according to type and density of crops around the children's homes, also taking into account traffic pollution and high-voltage power line magnetic field exposure.

RESULTS

Childhood leukemia risk did not increase in relation with any of the crop types with the exception of arable crops, characterized by the use of 2.4-D, MCPA, glyphosate, dicamba, triazine and cypermethrin. The very few children (n=11) residing close to arable crops had an OR for childhood leukemia of 2.04 (95% CI 0.50-8.35), and such excess risk was further enhanced among children aged <5 years.

CONCLUSIONS

Despite the null association with most crop types and the statistical imprecision of the estimates, the increased leukemia risk among children residing close to arable crops indicates the need to further investigate the involvement in disease etiology of passive exposure to herbicides and pyrethroids, though such exposure is unlikely to play a role in the vast majority of cases.