Mental health impacts of environmental exposures: A scoping review of evaluative instruments.

To date, much of the health focus of environmental policy has been on preventing physical health impacts of environmental exposures. Recent research has however highlighted increasingly concurrent mental health effects and its consideration is an emerging requirement for many governments and their agencies, yet there are limited universal mental health assessment tools for environmental exposures. This paper details the findings of a scoping review that evaluated assessment tools used to measure psychological impacts from environmental exposures and pollution, as reported in recent peer-reviewed literature (2000-2022). Across the 126 papers identified in our review, a wide range of tools to assess mental health impact were identified. We document a clear recent upswing of research interest in the mental and psychological impacts of environmental exposures, and an overarching concern for air pollution from industry, traffic, and fires. A majority of studies utilised standardised assessment instruments, but there was little consistency in the way that these were combined or deployed. The dominant mental health outcomes of interest in these studies were depression, anxiety, and mental and psychiatric health. The findings of the review identify a need and opportunity to develop a best-practice approach to consistently assess the mental health impacts arising from environmental exposures. Future work is needed to define the most appropriate choice and application of assessment tools to evaluate adverse mental health impacts from environmental exposures. This will support a more universal, coordinated and cross-jurisdiction approach for the assessment, quantification and targeted response to addressing mental health impacts arising from environmental exposures.

Associations of urinary zinc exposure with blood lipid profiles and dyslipidemia: Mediating effect of serum uric acid.

The relationship between zinc (Zn) exposure and abnormal blood lipids including dyslipidemia is contentious. Serum uric acid (SUA) has been reported to be correlated to both Zn exposure and dyslipidemia. The underlying mechanisms of Zn exposure associated with blood lipids and the mediating effects of SUA remain unclear. Therefore, this study analyzed the data from Chinese 2110 adults (mean age: 59.0 years old) in rural areas across China to explore the associations of Zn exposure with blood lipid profiles and dyslipidemia, and to further estimate the mediating effects of SUA in these relationships. The study data showed that urinary Zn was associated with increased levels of blood lipid components triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C). Moreover, an increased risk of dyslipidemia was observed in the study participants who had higher urinary Zn levels. Compared with the first quartile, the fourth quartile of urinary Zn concentration corresponded to the increase of TG (ß = 0.20, 95 % CI: 0.12, 0.28), LDL-C (ß = 0.06, 95 % CI: 0.01, 0.10) and dyslipidemia risk (OR = 2.16, 95 % CI: 1.50, 3.10), respectively. Elevated urinary Zn was also associated with higher levels of SUA and hyperuricemia risk. The SUA levels were positively related to total cholesterol (TC), TG, LDL-C levels and dyslipidemia risk. Mediation analyses revealed that SUA mediated 31.75 %, 46.16 % and 19.25 % of the associations of urinary Zn with TG, LDL-C levels and dyslipidemia risk, respectively. The subgroup and sensitivity analyses confirmed the positive associations between urinary Zn and blood lipid profiles and the mediating effect of SUA. The national population-based study further enhanced our understanding of the associations between Zn exposure and blood lipid profiles and mediating effect of SUA among generally healthy, middle-aged, and elderly individuals.

Tracing nickel smelter emissions using European honey bees.

This study investigated trace element contamination in honey bees inhabiting urban areas around the South Pacific's largest and longest operating nickel smelter in Nouméa, New Caledonia. There remains a paucity of research on the environmental impact of nickel smelting, and to date, there has been no assessment of its effects on the popular practice of beekeeping, or whether honey bees are a suitable tracer for nickel smelting emissions. Honey bees and honey were sampled from 15 hives across Nouméa to ascertain linkages between nickel smelter emissions, environmental contamination, and trace element uptake by bees. Comparison of washed and unwashed bees revealed no significant difference in trace element concentrations, indicating trace elements bioaccumulate within the internal tissues of bees over time. Accordingly, trace element concentrations were higher in dead bees than those that were sampled live, with smelter related elements chromium, cobalt and nickel being significantly different at p < 0.05. Except for boron, trace element concentrations were consistently higher in bees than in honey, suggesting that the transfer of trace elements from bees during honey production is negligible. Elevated concentrations of potentially toxic trace elements including cobalt, chromium and nickel in bees declined with distance from smelting operations (Spearman's Rho, p < 0.05), indicating the relationship between environmental contamination and the uptake of trace elements by bees. The findings of this study emphasise potential environmental and human health risks associated with trace element contamination from nickel smelting operations and affirm the use of honey bees as a biomonitor of potentially harmful nickel smelting emissions.

Tracing the Sources and Prevalence of Class 1 Integrons, Antimicrobial Resistance, and Trace Elements Using European Honey Bees.

Surveillance of antimicrobial resistance is essential for an effective One Health response. This study explores the efficacy of European honey bees (Apis mellifera) for biomonitoring antimicrobial resistance (AMR) in urban areas. Class 1 integrons (intI1) are investigated as a universal AMR indicator, as well as associated cassette arrays and trace element contaminants at a city-wide scale. Class 1 integrons were found to be pervasive across the urban environment, occurring in 52% (75/144) of the honey bees assessed. The area of waterbodies within the honey bee's foraging radius was associated with intI1 prevalence, indicating an exposure pathway for future investigation to address. Trace element concentrations in honey bees reflected urban sources, supporting the application of this biomonitoring approach. As the first study of intI1 in honey bees, we provide insights into the environmental transfer of bacterial DNA to a keystone species and demonstrate how intI1 biomonitoring can support the surveillance of AMR.

Predictive modeling of indoor dust lead concentrations: Sources, risks, and benefits of intervention.

Lead (Pb) contamination continues to contribute to world-wide morbidity in all countries, particularly low- and middle-income countries. Despite its continued widespread adverse effects on global populations, particularly children, accurate prediction of elevated household dust Pb and the potential implications of simple, low-cost household interventions at national and global scales have been lacking. A global dataset (∼40 countries, n = 1951) of community sourced household dust samples were used to predict whether indoor dust was elevated in Pb, expanding on recent work in the United States (U.S.). Binned housing age category alone was a significant (p < 0.01) predictor of elevated dust Pb, but only generated effective predictive accuracy for England and Australia (sensitivity of ∼80%), similar to previous results in the U.S. This likely reflects comparable Pb pollution legacies between these three countries, particularly with residential Pb paint. The heterogeneity associated with Pb pollution at a global scale complicates the predictive accuracy of our model, which is lower for countries outside England, the U.S., and Australia. This is likely due to differing environmental Pb regulations, sources, and the paucity of dust samples available outside of these three countries. In England, the U.S., and Australia, simple, low-cost household intervention strategies such as vacuuming and wet mopping could conservatively save 70 billion USD within a four-year period based on our model. Globally, up to 1.68 trillion USD could be saved with improved predictive modeling and primary intervention to reduce harmful exposure to Pb dust sources.

Sources, pathways and concentrations of potentially toxic trace metals in home environments.

Despite ongoing concerns about trace metal and metalloid (trace metals) exposure risks from indoor dust, there has been limited research examining their sources and relationship to outdoor soils. Here we determine the concentrations and sources for potentially toxic trace metals arsenic (As), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) and their pathways into homes in Sydney, Australia, using home-matched indoor dust (n = 166), garden soil (n = 166), and road dust samples (n = 51). All trace metals were more elevated indoors versus their matched garden soil counterparts. Indoor Cu and Zn dust concentrations were significantly more enriched than outdoor dusts and soils, indicating indoor sources were more relevant for these elements. By contrast, even though Pb was elevated in indoor dust, garden soil concentrations were correspondingly high, indicating that it remains an important source and pathway for indoor contamination. Elevated concentrations of As, Pb and Zn in garden soil and indoor dust were associated with home age (>50 years), construction materials, recent renovations and deteriorating interior paint. Significant correlations (p < 0.05) between road dust and garden soil Cu concentrations, and those of As and Zn in soil and indoor dust, and Pb across all three media suggest common sources. Scanning electron microscopy (SEM) analysis of indoor dust samples (n = 6) showed that 57% of particles were derived from outdoor sources. Lead isotopic compositions of soil (n = 21) and indoor dust (n = 21) were moderately correlated, confirming the relevance of outdoor contaminants to indoor environments. This study illustrates the source, relationship and fate of trace metals between outdoor and indoor environments. The findings provide insight into understanding and responding to potentially toxic trace metal exposures in the home environment.

Influence of iron ore properties on dioxin emissions during iron ore sintering.

Iron ores are principal input materials for iron and steel-making industries. Quality of iron ores is one of the critical parameters for formation of environmental pollutants related to the steel-making process. Dioxins are identified as one of the most toxic pollutants emitted during ironmaking, specifically during the sintering process. This study applied four types of iron ores and analyzed their moisture, density, particle size distribution and element concentrations to investigate their effect on the dioxin formation during sintering. Each type of iron ore was processed in a sinter pot grate. During each processing route, exhausted dust and generated sinter products were collected and subjected to PCDD/F and PCB analysis. Statistical analysis was applied to assess correlations between properties of iron ores and exhausted dioxin emissions, identifying key contributors to dioxin formation during sintering process. Results showed that Fe in iron ores was positively and significantly related to PCB 114 formation in dust and confirmed its co-catalytic effect on dioxin formation. Concentrations of Al, Ti and Cl in iron ores greatly increased PCDD/F and PCB emissions in the sintered products compared to dioxins in dust samples. The S levels and density of iron ores were highly related to the increasing PCDD/F and PCB emissions in both sinter and dust samples. By contrast, concentrations of Si in iron ores played a significant role in decreasing PCDD/F and PCB emissions in both sinter and dust samples. This study also confirmed the optimum size (< 1 mm-2.59 mm) for iron ores, which helps reduce dioxin emissions without affecting the quality of iron and steel-making products.

International quantification of microplastics in indoor dust: prevalence, exposure and risk assessment.

This international scale study measured the prevalence of indoor microplastics (MPs) in deposited dust in 108 homes from 29 countries over a 1-month period. Dust borne MPs shape, colour, and length were determined using microscopy and the composition measured using µFTIR. Human health exposure and risk was assessed along with residential factors associated with MPs via a participant questionnaire. Samples were categorised according to each country's gross national income (GNI). Synthetic polymers dominated in low income (LI) (39%) and high income (HI) (46%) while natural fibres were the most prevalent in medium income (MI) (43%) countries. Composition and statistical analysis showed that the main sources of MPs and dust were predominantly from indoor sources. Across all GNI countries, greater vacuuming frequency was associated with lower MPs loading. High income country samples returned higher proportions of polyamides and polyester fibres, whereas in LI countries polyurethane was the most prominent MPs fibre. Exposure modelling showed infants (0-2 years) were exposed to the highest MPs dose through inhalation (4.5 × 10-5 ± 3 × 10-5) and ingestion (3.24 × 10-2 ± 3.14 × 10-2) mg/kg-Bw/day. Health risk analysis of constituent monomers of polymers indicates cancer incidence was estimated at 4.1-8.7 per million persons across age groups. This study's analysis showed socio-economic factors and age were dominant variables in determining dose and associated health outcomes of MPs in household dust.

Lead poisoning of backyard chickens: Implications for urban gardening and food production.

Increased interest in backyard food production has drawn attention to the risks associated with urban trace element contamination, in particular lead (Pb) that was used in abundance in Pb-based paints and gasoline. Here we examine the sources, pathways and risks associated with environmental Pb in urban gardens, domestic chickens and their eggs. A suite of other trace element concentrations (including As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn) are reported from the sampled matrices. Sixty-nine domestic chickens from 55 Sydney urban gardens were sampled along with potential sources (feed, soil, water), blood Pb concentrations and corresponding concentrations in eggs. Age of the sampled chickens and house age was also collected. Commercial eggs (n = 9) from free range farms were analysed for comparative purposes. Study outcomes were modelled using the large Australian VegeSafe garden soil database (>20,000 samples) to predict which areas of inner-city Sydney, Melbourne and Brisbane are likely to have soil Pb concentrations unsuitable for keeping backyard chickens. Soil Pb concentrations was a strong predictor of chicken blood and egg Pb (p=<0.00001). Almost 1 in 2 (n = 31/69) chickens had blood Pb levels >20 µg/dL, the level at which adverse effects may be observed. Older homes were correlated with higher chicken blood Pb (p = 0.00002) and egg Pb (p = 0.005), and younger chickens (<12 months old) had greater Pb concentrations, likely due to increased Pb uptake during early life development. Two key findings arose from the study data: (i) in order to retain chicken blood Pb below 20 µg/dL, soil Pb needs to be < 166 mg/kg; (ii) to retain egg Pb < 100 µg/kg (i.e. a food safety benchmark value), soil Pb needs to be < 117 mg/kg. These concentrations are significantly lower than the soil Pb guideline of 300 mg/kg for residential gardens. This research supports the conclusion that a large number of inner-city homes may not be suitable for keeping chickens and that further work regarding production and consumption of domestic food is warranted.

Effect of Plasma and Blood Donations on Levels of Perfluoroalkyl and Polyfluoroalkyl Substances in Firefighters in Australia: A Randomized Clinical Trial.

Importance: Elevated levels of blood perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been associated with a range of adverse health outcomes. Firefighters have been exposed to PFASs in firefighting foams and have previously been shown to have higher PFAS levels in blood samples than the general population. No interventions have been shown to reduce PFAS levels. Objective: To examine the effect of blood or plasma donations on PFAS levels in firefighters in Australia. Design, Setting, and Participants: This 52-week, open-label, randomized clinical trial enrolled participants from May 23 to August 23, 2019. Participants were 285 Fire Rescue Victoria staff or contractors with serum levels of perfluorooctane sulfonate (PFOS) of 5 ng/mL or more who were eligible to donate blood, had not donated blood in the 3 months prior to randomization, and were able to provide written informed consent. Analysis was performed on an intention-to-treat basis from May to July 2021. Interventions: Firefighters with baseline PFOS levels of 5 ng/mL or more were randomly assigned to donate plasma every 6 weeks for 12 months, donate blood every 12 weeks for 12 months, or be observed only. Main Outcomes and Measures: The primary end points were changes in the serum PFOS and perfluorohexane sulfonic acid (PFHxS) levels after 12 months of plasma or blood donations or after observation only. Secondary end points included changes in serum PFAS levels from week 52 to week 64, changes in other PFASs, and changes in complete blood count, biochemistry, thyroid function, and lipid profile from screening to week 52. Results: A total of 285 firefighters (279 men [97.9%]; mean [SD] age, 53.0 [8.4] years) were enrolled; 95 were randomly assigned to donate plasma, 95 were randomly assigned to donate blood, and 95 were randomly assigned to be observed. The mean level of PFOS at 12 months was significantly reduced by plasma donation (-2.9 ng/mL; 95% CI, -3.6 to -2.3 ng/mL; P < .001) and blood donation (-1.1 ng/mL; 95% CI, -1.5 to -0.7 ng/mL; P < .001) but was unchanged in the observation group. The mean level of PFHxS was significantly reduced by plasma donation (-1.1 ng/mL; 95% CI, -1.6 to -0.7 ng/mL; P < .001), but no significant change was observed in the blood donation or observation groups. Analysis between groups indicated that plasma donation had a larger treatment effect than blood donation, but both were significantly more efficacious than observation in reducing PFAS levels. Conclusions and Relevance: Plasma and blood donations caused greater reductions in serum PFAS levels than observation alone over a 12-month period. Further research is needed to evaluate the clinical implications of these findings. Trial Registration: anzctr.org.au Identifier: ACTRN12619000204145.

Spatial distribution and composition of mine dispersed trace metals in residential soil and house dust: Implications for exposure assessment and human health.

Trace metal exposure from environmental sources remains a persistent global problem, particularly in communities residing adjacent to metal extraction and processing industries. This study examines front yard soil and house dust from 62 residences throughout the Australian Ag-Pb-Zn mining city of Broken Hill to better understand spatial variability in metal distributions, compositions and exposures across an industrially polluted urban environment. X-ray fluorescence analysis of paired soil/dust samples indicated that geomean concentrations (mg/kg) of Cu (32/113), Zn (996/1852), As (24/34) and Pb (408/587) were higher in house dust while Ti (4239/3660) and Mn (1895/1101) were higher in outdoor soil. Ore associated metals and metalloids (Mn, Zn, As, Pb) in soil and house dust were positively correlated and declined in concentration away from mining areas, the primary source of metalliferous emissions in Broken Hill. The rate of decline was not equivalent between soil and house dust, with the indoor/outdoor concentration ratio increasing with distance from mining areas for Zn/Pb (geomean = 1.25/1.05 (<1 km); 2.14/1.52 (1-2 km); 2.54/2.04 (>2 km)). House dust and Broken Hill ore Pb isotopic compositions (206Pb/207Pb; 208Pb/207Pb) were more similar in homes nearest to mining areas than those further away (geomean apportioned ore Pb = 88% (<1 km); 76% (1-2 km); 66% (>2 km)), reflecting spatial shifts in the balance of sources contributing to indoor contamination. Incorporation of house dust Pb reduced overestimation of IEUBK modelled blood Pb concentrations compared to when only soil Pb was used. These findings demonstrate that even in contexts where the source and environmental burden of metals are relatively apparent, geochemical relationships and exposures between outdoor and indoor environments are not always predictable, nor easily disaggregated.

International Analysis of Sources and Human Health Risk Associated with Trace Metal Contaminants in Residential Indoor Dust.

People spend increasing amounts of time at home, yet the indoor home environment remains understudied in terms of potential exposure to toxic trace metals. We evaluated trace metal (and metalloid) concentrations (As, Cu, Cr, Mn, Ni, Pb, and Zn) and health risks in indoor dust from homes from 35 countries, along with a suite of potentially contributory residential characteristics. The objective was to determine trace metal source inputs and home environment conditions associated with increasing exposure risk across a range of international communities. For all countries, enrichments compared to global crustal values were Zn > Pb > Cu > As > Cr > Ni; with the greatest health risk from Cr, followed by As > Pb > Mn > Cu > Ni > Zn. Three main indoor dust sources were identified, with a Pb-Zn-As factor related to legacy Pb sources, a Zn-Cu factor reflecting building materials, and a Mn factor indicative of natural soil sources. Increasing home age was associated with greater Pb and As concentrations (5.0 and 0.48 mg/kg per year of home age, respectively), as were peeling paint and garden access. Therefore, these factors form important considerations for the development of evidence-based management strategies to reduce potential risks posed by indoor house dust. Recent findings indicate neurocognitive effects from low concentrations of metal exposures; hence, an understanding of the home exposome is vital.

Trace element contamination of soil and dust by a New Caledonian ferronickel smelter: Dispersal, enrichment, and human health risk.

Metallurgical industries remain a considerable source of trace element contamination and potential human health risk. Determination of sources is a key challenge. With respect to the South Pacific's largest and longest operating metallurgic smelter in Nouméa, New Caledonia, determining the environmental impact and subsequent human health risk associated with local ferronickel smelting is complicated by natural geological enrichment of Ni and Cr. This study applies a multi-method and multi-matrix approach to disentangle smelter emissions from geogenic sources and model the consequent health risk from industrial activity. Dust wipes (n = 108), roadside soil (n = 91), garden soil (n = 15) and household vacuum dust (n = 39) were assessed to explore geospatial trace element (As, Cr, Cu, Fe, Mn, Ni, Pb, S, V and Zn) variations across outdoor and indoor environments. Enrichment factors (EF) identified elevated levels of smelter-related trace elements: S (EF = 7), Ni (EF = 6) and Cr (EF = 4), as well as Zn (EF = 4). Smelter-related elements in soil and dust deposits were negatively correlated with distance from the facility. Similarity of Pb isotopic compositions between dust wipes, surface soil and vacuum dust indicated that potentially toxic trace elements are being tracked into homes. Non-carcinogenic health risk modelling (Hazard Index, HI) based on 15 spatial nodes across Nouméa revealed widespread exceedance of tolerable risk for children (0-2 years) for Ni (HI 1.3-15.8) and Mn (HI 0.6-1.8). Risk was greatest near the smelter and to the north-west, in the direction of prevailing wind. Given the elevated cancer risk documented in New Caledonia, disentanglement of environmental from industrial sources warrants further attention to ensure community health protection. Our analysis illustrates how the confounding effects from complex environmental factors can be distilled to improve the accuracy of point source apportionment to direct future mitigation strategies.

Data for modelling vegetable uptake of trace metals in soil for the VegeSafe program.

Here we detail the soil to vegetable transfer factor (uptake) data and calculation procedures for vegetable trace metal uptake estimation that are presented in Taylor et al. (2021). Firstly, we present the literature review of trace metal uptake data, describing uptake from soil to vegetable produce determined in global experimental studies. After selecting the uptake factors most applicable to the VegeSafe dataset, using similar soil trace metal concentrations and studies that consider only the edible parts of plants, we applied these uptake factors to VegeSafe soils. Using this approach, we were able to estimate trace metal concentrations in home grown produce across the 3,609 homes included in our VegeSafe study. Using Australian and global food standards, we calculated the soil trace metal concentrations that would potentially result in exceedance of Australian and global food safety criteria. Our process followed the method detailed in the Australian soil guidelines (NEPM, 2013). Also presented are the numbers of individual samples and vegetable gardens that are likely to exceed food safety criteria in the three largest cities of Australia: Sydney, Melbourne and Brisbane. Individual household vegetable garden trace metal uptake data were aggregated across standarised geographic areas (Statistical Area Level 3) as established by the Australian Bureau of Statistics to visualise the geospatial distribution of potential trace metal risk from home produce. These modelled data provide the basis for prioritising locations, trace metals and soils for future empirically-based studies of trace metal contamination in home-grown produce.

A citizen science approach to identifying trace metal contamination risks in urban gardens.

We launched the VegeSafe program in 2013 to assist Australians concerned about exposure to contaminants in their soils and gardens. VegeSafe analyses garden soils provided by citizens for trace metals at our laboratory at little to no cost, with easy-to-follow guidance on any intervention required. The response was overwhelming-Australians submitted 17,256 soils from 3,609 homes, and in turn VegeSafe researchers now have unparalleled household-scale data, providing new insights into urban trace metal contamination. The results are sobering, with 35% of homes, particularly those that are older, painted and located in inner cities having soils above the Australian residential guideline (300 mg/kg) for the neurotoxic trace metal lead (Pb). Exposure pathway, blood Pb concentration and vegetable uptake modelling showed the communities in these locations were most at risk. VegeSafe is transformative: 94% of participants better understood contaminants, 83% felt safer in their home environment and 40% undertook remedial action based on their results. The two-way nature of this program enables education of citizens about environmental contaminants, advances public health, and delivers impactful science.

Quantification and exposure assessment of microplastics in Australian indoor house dust.

Limited attention has been given to the presence of MPs in the atmospheric environment, particularly in indoor environments where people spend about 90% of their time. This study quantitatively assesses the prevalence, source and type of MPs in Australian homes with the goal of evaluating human health exposure potential. Thirty-two airborne indoor deposited dust samples were collected in glass Petri dishes from Sydney (Australia) homes, over a one-month period in 2019. Participants completed a questionnaire on their household characteristics. Samples were analysed using a stereomicroscope, a fluorescent microscope and micro-Fourier transform infrared (FTIR) spectroscopy for their colour, size, shape and composition. Inhalation and ingestion rates were modelled using US EPA exposure factors. Microplastic fibre deposition rates ranged from 22 to 6169 fibres/m2/day. Deposited dust comprised 99% fibres. The highest proportion of fibres (19%) were 200-400 µm in length. The majority were natural (42%); 18% were transformed natural-based fibres; and 39% were petrochemical based. A significant difference was observed between the deposition rate and the main floor covering (p-value <0.05). Polyethylene, polyester, polyamide, polyacrylic, and polystyrene fibres were found in higher abundance in homes with carpet as the main floor covering. Where carpet was absent, polyvinyl fibres were the most dominant petrochemical fibre type, indicating the role of flooring materials (e.g. wood varnishes) in determining MP composition. Vacuum cleaner use was significantly related to MP deposition rates (p-value <0.05). MP ingestion rates peaked at 6.1 mg/kg-Bw/year for ages 1-6, falling to a minimum of 0.5 mg/kg-Bw/year in >20 years age group. Mean inhaled MP weight and count was determined to be 0.2±0.07 mg/kg-Bw/year and 12891±4472 fibres/year. Greatest inhalation intake rates were for the <0.5-yr age group, at 0.31 mg/kg-Bw/year. The study data reveal that MPs are prevalent in Australian homes and that the greatest risk of exposure resides with young children. Notwithstanding the limited number of global studies and the different methods used to measure MPs, this study indicates Australian deposition and inhalation rates are at the lower end of the exposure spectrum.

Blood lead levels in low-income and middle-income countries: a systematic review.

BACKGROUND: Since the global phase-out of leaded petrol, reports have suggested that lead exposure remains substantial or is increasing in some low-income and middle-income countries (LMICs). However, few studies have attempted to systematically assess blood lead levels over the full range of LMICs. We aimed to describe values for blood lead level in LMICs. METHODS: In this systematic review, we searched PubMed for studies published between Jan 1, 2010, and Oct 31, 2019, that reported blood lead levels in the 137 countries in World Bank LMIC groupings. Studies were reviewed for inclusion if they contained blood lead level data from human populations residing in any given country; comprised at least 30 participants; presented blood lead level data derived from venous, capillary, or umbilical cord samples of whole blood; had data that were collected after Dec 31, 2004; and were published in English. Data on blood lead level were extracted and pooled, as appropriate, to make country-specific estimates of the distribution of background blood lead levels among children and adults, along with information on specific sources of exposure where available. This study is registered with PROSPERO, number CRD42018108706. FINDINGS: Our search yielded 12 695 studies, of which 520 were eligible for inclusion (1100 sampled populations from 49 countries comprising 1 003 455 individuals). Pooled mean blood lead concentrations in children ranged from 1·66 µg/dL (SD 3·31) in Ethiopia to 9·30 µg/dL (11·73) in Palestine, and in adults from 0·39 µg/dL (1·25) in Sudan to 11·36 µg/dL (5·20) in Pakistan. Background values for blood lead level in children could be pooled in 34 countries and were used to estimate background distributions for 1·30 billion of them. 632 million children (95% CI 394 million-780 million; 48·5%) were estimated to have a blood lead level exceeding the US Centers for Disease Control's reference value of 5 µg/dL. Major sources of lead exposure were informal lead acid battery recycling and manufacture, metal mining and processing, electronic waste, and the use of lead as a food adulterant, primarily in spices. INTERPRETATION: Many children have a blood lead level exceeding 5 µg/dL in LMICs, despite leaded petrol phase-outs. Given the toxicity of lead, even at low amounts of exposure, urgent attention is required to control exposures and to expand population-based sampling in countries with no or scant data. FUNDING: This work was supported by the United States Agency for International Development (Cooperative Agreement number AID-OAA-A-16-00019).

Atmospheric remobilization of natural and anthropogenic contaminants during wildfires.

Globally, wildfires are increasing in frequency and severity, exposing populations to toxic trace elements stored within forests. Trace element and Pb isotope compositions in aerosols (n = 87) from four major wildfires near Sydney, Australia (1994-2004) were evaluated (Mood's median test) to determine any significant differences in concentration before, during or after wildfires. The US EPA's positive matrix factorization (PMF) model was used to distinguish a wildfire-related particulate source factor. Atmospheric concentrations of Cd and Mn were approximately 2.5 times higher during fire periods. PMF modelling distinguished a soil factor (Ca, Si, Ti and Zn) and an anthropogenically-sourced factor (Cd, Pb). The Cd, Pb anthropogenic factor was present at twice the concentration during wildfire periods (compared to before or after). Lead isotopic analyses of aerosols revealed that former leaded gasoline depositions were subject to remobilization during post-2000 wildfire periods. Trace element increases during wildfires are unlikely to exceed health-based criteria.

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

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