Mutagenicity, genotoxicity and carcinogenic risk assessment of indoor dust from three major cities around the Pearl River Delta

Validation of the analytical methodology used in obtaining the oral bioavailability of organic target pollutants in atmospheric particulate matter (PM10) applying an in-vitro method

In recent years, scientists have started evaluating the portion of PM-bound pollutants that may be liberated (bioaccessible fraction) in human fluids and spread through the digestive system ultimately entering systemic circulation (known as the bioavailable fraction). In the current research, an analytical procedure was validated and applied to characterize the oral bioavailable fraction of PM10 samples. The approach encompassed the determination of 49 organic contaminants. The proposed method aims to biomimetic complete mouth-gastric-intestinal system basing on an adaptation of the unified bioaccessibility method (UBM) modified by the inclusion of a dialysis membrane to mimic intestinal absorption and obtain the orally bioavailable fractions. It was followed by a vortex-assisted liquid-liquid extraction (VALLE) step, using gas chromatography-tandem mass spectrometry (GC-MS/MS). Analytical procedure was effectively validated by employing selected reaction monitoring (SRM) mode in MS/MS, matrix-matched calibration, and deuterium-labelled surrogate standards. This approach ensured heightened sensitivity, minimized matrix effects, and compensated for any losses during the process. The validation process covered various aspects, including studying linearity, determining detection and quantification limits, assessing analytical recoveries at three concentration levels, and evaluating precision both within a single day and across multiple days. The validated method was applied to PM10 samples, revealing that polycyclic aromatic hydrocarbons (PAHs) were the most frequently detected, with significant seasonal variations in their concentrations. Organophosphorus flame retardants (OPFRs) like TCPP were also detected in bioavailable fractions, highlighting their potential health impact. Bisphenols, SMCs, and PAEs were not detected, suggesting low levels in the studied urban area. Further research is needed to understand the bioavailability of PM-bound pollutants in different environments.

To breathe or not to breathe: Inhalational exposure to heavy metals and related health risk

This study reviewed scientific literature on inhalation exposure to heavy metals (HMs) in various indoor and outdoor environments and related carcinogenic and non-carcinogenic risk. A systematic search in Web of Science, Scopus, PubMed, Embase, and Medline databases yielded 712 results and 43 articles met the requirements of the Population, Exposure, Comparator, and Outcomes (PECO) criteria. Results revealed that HM concentrations in most households exceeded the World Health Organization (WHO) guideline values, indicating moderate pollution and dominant anthropogenic emission sources of HMs. In the analyzed schools, universities, and offices low to moderate levels of air pollution with HMs were revealed, while in commercial environments high levels of air pollution were stated. The non-carcinogenic risk due to inhalation HM exposure exceeded the acceptable level of 1 in households, cafes, hospitals, restaurants, and metros. The carcinogenic risk for As and Cr in households, for Cd, Cr, Ni, As, and Co in educational environments, for Pb, Cd, Cr, and Co in offices and commercial environments, and for Ni in metros exceeded the acceptable level of 1 × 10-4. Carcinogenic risk was revealed to be higher indoors than outdoors. This review advocates for fast and effective actions to reduce HM exposure for safer breathing.

Chemical and genotoxic characterization of bioaccessible fractions as a comprehensive in vitro tool in assessing the health risk due to dust-bound contaminant ingestion

In the last two decades, awareness grew on the matter of the impact of environment on human health. Contaminants sorbed onto soil and settled dust can be ingested and thus represent a hazard, particularly to young children, who play on the ground and bring their hands and objects to their mouth. Metal(loid)s and polycyclic aromatic hydrocarbons (PAHs) are of concern as they are both carcinogenic to humans and ubiquitous in outdoor environments. The present study aims to assess the total and bioaccessible fractions of PAHs and metal(loid)s present in settled dust of four preschools located in industrial, urban, and suburban areas. On the one hand, children's incremental life cancer risks (ILCR) were calculated according to ingestion pathway. On the other hand, the genotoxicities of the bioaccessible dust-bonded contaminants were determined on gastric cells. PAH concentrations ranged from 50.9 to 2267.3 ng/g, and the bioaccessible fraction represented 10.7% of the total in average. Metal(loid) concentration ranged from 12,430 to 38,941 µg/g, and the mean bioaccessibility was of 40.1%. Cancer risk ranged from 2.8.105 to 8.6.105, indicating that there is a potential cancer risk for children linked to the ingestion of settled dust. The inorganic bioaccessible fraction induced little DNA (< 20%TailDNA) and chromosomal damages (30% increase in micronuclei), whereas the organic bioaccessible fraction induced higher DNA (17-63%TailDNA) and chromosomal damages (88% increase in micronuclei). Such experimental approach needs to be deepen, as a tool complementary to cancer risk calculation, since the latter only lays on a set of targeted contaminants with known toxicity values.

Evaluating the Contamination by Indoor Dust in Dubai

Nowadays, people spend most of their time indoors. Despite constantly cleaning these spaces, dust apparition cannot be avoided. Since dust can contain chemical elements that negatively impact people's health, we propose the analysis of the metals from the indoor dust component collected in different locations in Dubai, UAE. Multivariate statistics (correlation matrix, clustering) and quality indicators (QI)-Igeo, PI, EF, PLI, Nemerow-were used to assess the contamination level with different metals in the dust. We proposed two new QIs (CPI and AQI) and compared the results with those provided by the most used indices-PLI and Nemerow. It is shown that high concentrations of some elements (Ca in this case) can significantly increase the values of the Nemerow index, CPI, and AQI. In contrast, the existence of low concentrations leads to the decrement of the PLI.

Toward an interdisciplinary approach to assess the adverse health effects of dust-containing polycyclic aromatic hydrocarbons (PAHs) and metal(loid)s on preschool children

Settled dust can function as a pollutant sink for compounds, such as polycyclic aromatic hydrocarbons (PAHs) and metal(loid)s (MMs), which may lead to health issues. Thus, dust represents a hazard specifically for young children, because of their vulnerability and hand-to-mouth behavior favoring dust ingestion. The aim of the present study was to explore the influence of the season and the microenvironment on the concentrations of 15 PAHs and 17 MMs in indoor and outdoor settled dust in three preschools (suburban, urban, and industrial). Second, the potential sources and health risks among children associated with dust PAHs and MMs were assessed. Third, domestic factors (risk perception, knowledge and parental style) were described to explore protective parental behaviors toward dust hazards. The suburban preschool had the lowest concentrations of dust PAHs and MMs, while the industrial and urban preschools had higher but similar concentrations. Seasonal tendencies were not clearly observed. Indoor dusts reflected the outdoor environment, even if specific indoor sources were noted. Source analysis indicated mainly vehicular emissions, material release, and pyrogenic or industrial sources. The non-cancer health risks were non-existent, but potential cancer health risks (between 1.10-6 and 1.10-4) occurred at all sampling locations. Notably, the highest cancer risk was observed in a playground area (>1.10-4) and material release should be further addressed. Whereas we assessed higher risk indoors, parents perceived a higher risk in the open-air environment and at the preschool than at home. They also perceived a lower risk for their own children, revealing an optimism bias, which reduces parental anxiety.

Bio-accessibility and health risk assessment of some selected heavy metals in indoor dust from higher institutions in Ondo State, Nigeria

Risks of heavy metal exposure from contaminated indoor dust constitute a major threat to human health. In this paper, heavy metals in deposited indoor dust samples from four tertiary institutions in Ondo State, Nigeria-Federal University of Technology, Akure; Federal College of Agriculture, Akure; Ondo State College of Health Science Technology, Akure; and Adeyemi College of Education, Ondo-were examined. The samples were collected from each location by dusting the surfaces of doors, windows, and bookshelves in lecture rooms, hostels, laboratories, and libraries, homogenized into a representative composite, and analyzed for Cr, Pb, Cd, Cu, and Zn using a flame atomic absorption spectrophotometer (FAAS) to assess their potential health risk to humans. Cu had the highest mean metal concentration in the range (0.18-0.31 mg/kg) and Cd had the lowest (ND-0.02 mg/kg) in the study. Samples from Federal College of Agriculture had the highest metal concentration, while those from Ondo State College of Health Science Technology had the lowest. The average daily dose (ADD) through ingestion was determined to be the key exposure pathway in a non-carcinogenic investigation followed by ADD through dermal contact and ADD via inhalation accordingly. Despite this, the hazard quotients (HQ) and hazard indices (HI) were well below the safety limit of one. The study established that carcinogenic effect cannot be experienced with exposure to the studied dust samples. To retain the status, it is suggested that a reasonable level of safety and tight rules be implemented.

Assessment of house dust trace elements and human exposure in Ankara, Turkey

One of the impacts of the COVID-19 pandemic is leading people remain at homes longer than ever. Considering the elongation of the time people spend indoors, the potential health risks caused by contaminants including heavy metals in indoor environments have become even more critical. The purpose of this study was to evaluate the levels and sources of heavy metals in indoor dust, to assess the exposure to heavy metals via indoor dust, and to estimate the associated health risk. The highest median value was measured for Zn (263 μg g^-1), while the lowest median concentration value was observed for Cd (0.348 μg g^-1). The levels of elements measured in the current study were found to be within the ranges reported in the other parts of the world, mostly close to the lower end of the range. House characteristics such as proximity to the main street, presence of pets, number of occupants, and age of the building were the house characteristics influencing the observed higher concentrations of certain heavy metals in houses. Enrichment factor values range between 1.79 (Cr) and 20.4 (Zn) with an average EF value of 8.80 ± 6.80 representing that the targeted elements are enriched (EF>2) in indoor dust in Ankara. Positive matrix factorization results showed that the heavy metals in the house dust in the study area are mainly contributed from sources namely outdoor dust, carpets/furniture, solders, wall paint/coal combustion, and cigarette smoke. Carcinogenic and non-carcinogenic risk values from heavy metals did not exceed the safe limits recommended by EPA. The highest carcinogenic risk level was caused by Cr. The risk through ingestion was higher than inhalation, and the risk levels were higher for children than for adults.

Microplastics-sorbed phenanthrene and its derivatives are highly bioaccessible and may induce human cancer risks

Microplastics (MPs) are ubiquitous in environmental media and human diets and can enrich organic contaminants, including polycyclic aromatic hydrocarbons (PAHs) and their derivatives. The bioaccessibilities and triggering cancer risks of MP-sorbed PAHs and PAH derivatives are closely linked with human health, which, however, were rarely focused on. This study explored the sorption behaviors of phenanthrene (PHE) and PHE derivatives on polyethylene (PE), polypropylene (PP), and polystyrene (PS) MPs, and assessed their bioaccessibilities in gastrointestinal fluids as well as their inducing human cancer risks. PE MPs harbored the highest sorption capacity, secondly the PP MPs, then the PS ones. Sorption of PHE and PHE derivatives on MPs was positively correlated with their hydrophobicities. The bioaccessibilities of sorbed PHE and PHE derivatives could reach 53.59 %±0.46 %-90.28 %±0.92 % in gastrointestinal fluids and 81.34 %±0.77 %-98.72 %±1.44 % in gastrointestinal fluids with the addition of Tenax (more close to the bioavailability). The hydrophobicities also controlled the bioaccessibilities of PHE and PHE derivatives in gastric fluids, and those in intestinal fluids with Tenax for PS MPs. The incremental lifetime cancer risk (ILCR) values for PHE, PHE-Cl, and PHE-NO2 on MPs at tested concentrations were all higher than the USEPA-suggested safety limit (10-6), and most of them were even higher than 10-4, which thus indicates serious cancer risks. This study promoted our understanding of the potential health threats posed by organic pollutant-bearing MPs in the environment.

Ecotoxic emissions generated by illegal burning of household waste

The practice of burning household waste including different types of plastic is illegal in Hungary, still an existing problem. As environmental consequences are hardly known, this study attempts to give an initial estimation of the ecotoxicity generated during controlled combustion of different waste types. These samples included polystyrene (PS), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyurethane (PU), oriented strand board (OSB) and rag (RAG). Ecotoxicological profiling was completed using the following test battery: Vibrio fischeri bioluminescence inhibition assay, Daphnia magna immobility test and the seedling emergence assay. Also, genotoxicity of plastic waste samples was assessed using the SOS Chromotest. Concerning main pollutants in the samples, the samples could be distinguished as 'PAH-type' and 'heavy metal-type' samples. PVC, PU and PS samples showed the highest toxicity in the Vibrio and Daphnia assays. The PVC sample was characterized by an extremely high cadmium concentration (22.4 μg/L), PS, PP and PU samples on the contrary had high total PAH content. While Vibrio and Daphnia showed comparable sensitivity, the phytotoxicity assay had no response for any of the samples tested. Samples originating from the controlled burning of different plastic types such as PU, PVC, PS and PP were classified as genotoxic, PS sample showed extremely high genotoxicity. Genotoxicity expressed as SOSIF showed strong correlation with most of the PAHs detected.

Mutagenicity, health risk, and disease burden of exposure to organic micropollutants in water from a drinking water treatment plant in the Yangtze River Delta, China

A wide variety of organic micropollutants in drinking water pose a serious threat to human health. This study was aimed to reveal the characteristics of organic micropollution profiles in water from a drinking water treatment plant (DWTP) in the Yangtze River Delta, China and investigate the mutagenicity, health risk and disease burden through mixed exposure to micropollutants in water. The presence of organic micropollutants in seven categories in organic extracts (OEs) of water from the DWTP was determined, and Ames test was conducted to test the mutagenic effect of OEs. Meanwhile, health risk of exposure to organic micropollutants in finished water through three exposure routes (ingestion, dermal absorption and inhalation) was assessed with the method proposed by U.S. EPA, and disability-adjusted life years (DALYs) were combined to estimate the disease burden of cancer based on the carcinogenic risk (CR) assessment. The results showed that 28 organic micropollutants were detected in the raw and finished water at total concentrations of 967.28 ng/L and 1073.45 ng/L, respectively, of which phthalate esters (PAEs) were the dominant category (95.79% in the raw water and 96.61% in the finished water). Although the results of the Ames test for OEs were negative and the non-carcinogenic hazard index of the organic micropollutants in the finished water was less than 1 in all age groups, the total CR was 2.17 × 10^-5, higher than the negligible risk level (1.00 × 10^-6). The total DALYs caused by the organic micropollutants in the finished water was 2945.59 person-years, and the average individual DALYs was 2.21 × 10^-6 per person-year (ppy), which was 2.21 times the reference risk level (1.00 × 10^-6 ppy) defined by the WHO. Exposure to nitrosamines (NAms) was the major contributor to the total CR (92.06%) and average individual DALYs (94.58%). This study demonstrated that despite the negative result of the mutagenicity test with TA98 and TA100 strains, the health risk of exposure to organic micropollutants in drinking water should not be neglected.

Polycyclic aromatic hydrocarbons (PAHs) in indoor environments are still imposing carcinogenic risk

Polycyclic aromatic hydrocarbons (PAHs) are among the most health-relevant air pollutants. Herein, we conducted meta-analysis and experimental validation to evaluate PAHs in our surroundings and carcinogenic risks. We summarized the occurrence of PAHs in outdoors and indoors from 131 studies with 6,766 samples collected in different countries in 1989-2019. The global weighted-median concentration in outdoor air, indoor air and dust of ΣPAHs were 142 ng/m³, 369 ng/m³ and 10,201 ng/g; respectively. ΣPAHs have decreased in indoor air but remained steady in outdoor air and indoor dust. More carcinogenic PAHs in indoor/outdoor air was observed in Asia, while in dust was North America. Monte-Carlo simulation further showed indoor sources for children's exposure from dust and air can exceed outdoor. To further validate the health effect of PAHs from indoors, 15 more recent indoor dust samples were collected to examine their mutagenicity. The results showed that ΣPAHs were found to be significantly correlated with mutagenicity potency in the dust sample metabolically activated with liver S9 subcellular fraction and likely accounted for 0.42-0.50 of the mutagenic activity. Our findings indicated that PAHs are still likely to have carcinogenic activity in indoor environments and exposure risk of children to indoor dust should be emphasized.

Occurrence, potential sources, in vitro bioaccessibility and health risk assessment of heavy metal in indoor dust from different microenvironment of Bushehr, Iran

Indoor dust samples were collected from 42 microenvironments of residential buildings (RB, 15 samples), official buildings (OB, 10 samples), laboratory rooms (LR, 7 samples), and school classroom (SCR, 10 samples) in Bushehr, whereby the concentration of zinc, copper, lead, cadmium, nickel, and chromium was studied. The results of this study indicated that the mean concentrations of Zn, Cu, Pb, Cd, Cr, and Ni in the indoor dust samples were 567.18, 186.09, 209.01, 5.31, 143.20, and 57.09 mg/kg in RB, 1077.34, 539.67, 274.89, 8.12, 155.30, and 92.55 mg/kg in OB, 246.40, 149.56, 127.2, 1.96, 43.45, and 91.09 mg/kg in LR and 271.43, 189.84, 164.44, 3.06, 124.20, and 70.09 mg/kg in SCR. The results of principal cluster analysis showed that the heavy metals in indoor environments were mostly originated from smoking tobacco and cigarette, traffic sources, old building materials, and building paint colors. The results of this study also revealed that the concentration of heavy metals in indoor dust had a negative and significant relationship (P value < 0.05 in most cases) with rate of ventilation, and a positive and significant relationship with smoking inside buildings (P value < 0.05 in most cases). The bioaccessibility for zinc, copper, lead, cadmium, nickel, and chromium was 69.12, 40.08, 43.33, 79.81, 31.10, and 6.31%, respectively, in indoor dust. Further, risk assessment showed that the risk values of carcinogenicity and non-carcinogenicity resulting from heavy metals inside the studied microenvironments had exceeded the recommended safe limit by EPA. In terms of potential ecological risks, it was found that heavy metals in these microenvironments have exceeded the hazardous ecological levels presented by different indices and can have considerable negative ecological effects. Thus, it is essential that further and better studies and monitoring be performed on these environments, and suitable control recommendations and solutions should be regulated for this public health threat.

Dermal bioaccessibility and absorption of polycyclic aromatic hydrocarbons (PAHs) in indoor dust and its implication in risk assessment

Numerous studies have focused on assessing the risk of human exposure to polycyclic aromatic hydrocarbons (PAHs) in indoor dust via dermal contact. However, the dermal bioaccessibility and dermal absorption of PAHs in indoor dust have seldom been reported. In the present study, the effects of temperature, sweat ratio, solid-liquid ratio and incubation time on the dermal bioaccessibility of PAHs were examined. Naphthalene, phenanthrene, pyrene and benzo[a]pyrenewere selected for examination in an absorption assay with keratinocyte cells. The results showed the release of PAHs from indoor dust fitted a first-order one-compartment model. Naphthalene had the highest rate of release, which was consistent with the bioaccessibility assay results. In addition, the absorption rate of naphthalene and phenanthrene by keratinocytes was higher than that of pyrene and benzo[a]pyrene, with the latter being of higher molecular weight. These results indicated that low molecular weight PAHs were much more easily absorbed via dermal contact than were high molecular weight PAHs. The dermal bioavailability of PAHs in indoor dust was estimated by multiplying the bioaccessibility of PAHs in indoor dust by the ratio of dermal absorption by skin cells, and ranged from 0.12 to 51.0%. These data will be useful in risk assessments.

Distribution, sources and health risk of PAHs in urban air-conditioning dust from Hefei, East China

In recent decades, indoor air quality (IAQ) has become one of the most important human health issues. The potential properties and potential health hazards of polycyclic aromatic hydrocarbons (PAHs) are associated with their long-term residues, bioaccumulation and semivolatility, and they can also be transferred through a variety of media, such as the atmosphere, water and soil. Dust particles from indoor and outdoor emission sources adhere to A-C filters and can represent air quality to a certain extent. However, few studies have focused on PAHs in A-C filter dust in Hefei, China. In this study, 16 PAHs were selected, dust samples were collected from A-C filters from three different functional districts, and GC-MS analysis of the samples was performed. The concentration of the ∑16PAHs ranged from 7.34 to 326.84 μg g^-1, 5.07-15.34 μg g^-1, 4.09-47.26 μg g^-1 and 0.97-13.38 μg g^-1 in dust samples from the Administrative District (AD), Industrial District (ID), Commercial District (CD) and Outdoors (OD), respectively. The total PAH concentration in A-C dust was much higher than that in dust deposited outdoors in the urban area. The percentage of 5-6 ring PAHs accounted for more than 70% of the ∑16PAHs, which shows that the PAHs in A-C dust mainly come from pyrolysis rather than a diagenetic source. Principal component analysis (PCA) and diagnostic ratios were used in a source analysis, and the results indicated that the main PAHs emission sources in the different functional districts were coal, wood and biomass combustion. The incremental lifetime cancer risk (ILCR) values indicated a medium to high potential carcinogenic risk for adults and children exposed to dust with PAHs. Particularly, skin contact and ingestion of carcinogenic PAHs from dust are the major exposure pathways and present an exposure risk that is four to five orders of magnitude higher than the risk of inhalation.

Indoor Air Pollution, Related Human Diseases, and Recent Trends in the Control and Improvement of Indoor Air Quality

Indoor air pollution (IAP) is a serious threat to human health, causing millions of deaths each year. A plethora of pollutants can result in IAP; therefore, it is very important to identify their main sources and concentrations and to devise strategies for the control and enhancement of indoor air quality (IAQ). Herein, we provide a critical review and evaluation of the major sources of major pollutant emissions, their health effects, and issues related to IAP-based illnesses, including sick building syndrome (SBS) and building-related illness (BRI). In addition, the strategies and approaches for control and reduction of pollutant concentrations are pointed out, and the recent trends in efforts to resolve and improve IAQ, with their respective advantages and potentials, are summarized. It is predicted that the development of novel materials for sensors, IAQ-monitoring systems, and smart homes is a promising strategy for control and enhancement of IAQ in the future.

Concentration of phthalate esters in indoor and outdoor dust in Kocaeli, Turkey: implications for human exposure and risk

The interest in phthalate esters (PAEs) has increased in recent years because elevated phthalate levels have been detected in environmental matrices and they have certain adverse effects on human health. Indoor dust from 90 homes and outdoor (street) dust from outside these homes were collected in Kocaeli province between February and April 2016 and analyzed for eight PAEs. The total indoor dust concentrations of eight PAEs (Σ₈PAEs) ranged from 21.33 μg g^-1 to 1802 μg g^-1 (median, 387.67 μg g^-1), significantly higher than outdoor dust concentrations (0.16-36.85 μg g^-1 with median 4.84 μg g^-1). Di-2-ethylhexyl phthalate (DEHP) was the most dominant pollutant in both indoor and outdoor environments with a median value of 316.02 μg g^-1 and 3.89 μg g^-1, respectively, followed by di-n-butyl phthalate and butylbenzyl phthalate (BBP). DEHP was measured within the range of 198.54-816.92 μg g^-1 and BBP within the range of 15.52-495.33 μg g^-1 in homes with PVC coating, significantly higher than the levels in homes with parquet and tiled floor (p<0.05). Monte Carlo simulation was applied to probabilistically estimate exposure to PAEs and associated carcinogenic risk. The Σ₅PAE median values of non-dietary ingestion and dermal absorption exposure were estimated as 1.57 μg kg day^-1 and 0.007 μg kg day^-1 for children and 0.09 μg kg day^-1 and 0.04 μg kg day^-1 for adults while inhalation route exposure to PAE in dust was at a negligible level for both groups. Children were more exposed to PAEs through ingestion route (92.74% to 99.54% of the total exposure) while adult exposure through ingestion routes (62-68.4%) and dermal absorption (29.74% and 31.87% of the total exposure) were comparable. The mean cancer risk level via non-dietary ingestion of DEHP for children was 2.33×10^-6, about eight times higher than the levels for adults. The risk levels of about 16% of adults and 95% of children are greater than the threshold value of 10^-6 when the population is exposed to DEHP in indoor dust. Looking from the viewpoint of child health, the most effective method to reduce exposure among the measured PAEs is to keep the release of DEHP under control, especially in indoor environment, and to take precautions to reduce exposure.

Characteristics and health risk assessment of polycyclic aromatic hydrocarbons associated with dust in household evaporative coolers

This study reports a characterization of indoor polycyclic aromatic hydrocarbons (PAHs) associated with dust (dust-PAHs) in household evaporative coolers and their associated health effects. Extensive analysis showed that the indoor dust-PAHs stemmed mostly from pyrogenic sources (vehicular emissions) with mean total concentrations limited between 131 and 429 ng g^-1. The distribution pattern of PAHs based on number of rings exhibited the following order of decreasing relative abundance: 4 > 3 > 5 > 6 > 2 rings. Results indicate that the mutagenicity of dust-PAHs exceeded their carcinogenicity, but that the potential carcinogenic effects are still significant. The mean lifetime cancer risk for different age groups for three pathways based on Model 2 (dermal (1.39 × 10^-1 to 1.91 × 10^-2), ingestion (2.13 × 10^-3 to 8.08 × 10^-3) and inhalation (1.62 × 10^-7 to 4.06 × 10^-7)) was 7.4-146 times higher than values predicted by Model 1 (dermal (5.13 × 10^-5 to 3.03 × 10^-3), ingestion (9.34 × 10^-5 to 1.31 × 10^-3) and inhalation (7.13 × 10^-20 to 1.68 × 10^-20)). Hence, exposure to dust-PAHs in household evaporative coolers lead to high risk, especially for children (less than 11 years) (HQ = 2.71 × 10^-20 to 54.8 and LTCRs = 7.13 × 10^-20 to 1.39 × 10^-1). Strategies should be considered to eliminate such pollutants to protect people, especially children, from the non-carcinogenic and carcinogenic effects by changing household evaporative coolers with other cooling systems.

Human Health Risk Assessment for Toxic Trace Elements in the Yaro Mine and Reclamation Options

The aim of this study was to investigate the environmental impact and human health risks associated with toxic trace element (TTE) exposure in the abandoned Yaro Mine, Korea. Carcinogenic and non-carcinogenic risks were assessed separately for adults and children. Among the various pathways, the rate of TTE intake from the ingestion of groundwater was highest, followed in descending order by crop consumption, soil ingestion, and soil contact. The carcinogenic risk from the ingestion of groundwater was highest, followed by crop consumption and ingestion of contaminated surface soil. The non-carcinogenic risk from the ingestion of groundwater was highest (53.57% of the total non-carcinogenic risk), followed by crop intake (38.53%) and surface soil ingestion (4.80%). The risk assessment revealed that contaminated soil around Yaro mine posed a high risk to the health of inhabitants, mainly via groundwater ingestion and crop consumption. Reclamation measures should include methods of disrupting the high-risk routes between the source and recipient. Stabilization and covering techniques are promising options for reducing the hazard (i.e., exposure to the bioavailable fraction of TTE) and creating a chemical or physicochemical barrier to the potential migration pathways.

Road dust contamination by polycyclic aromatic hydrocarbons and their methylated derivatives in northern Vietnam: Concentrations, profiles, emission sources, and risk assessment

Concentrations of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) were examined in road dusts from some representative areas with different land-use types in northern Vietnam, providing updated information about the occurrence, sources, and risks of these pollutants in Southeast Asian region. The Vietnamese road dusts were contaminated with low to moderate levels of PAHs and Me-PAHs as compared to those from other countries in the world. Concentrations of PAHs and Me-PAHs (Σ34PAHs) decreased in the order: urban (median 1800; range 1100-5500) ≈ industrial (1300; 550-10,000) > suburban (450; 310-1300) ≈ rural road dust (330; 210-2300 ng g^-1), suggesting an urban-rural declining trend and effects of urbanization-industrialization processes in PAH emission extent in Vietnam. The profiles and diagnostic ratios of PAHs and Me-PAHs in our samples revealed that these compounds were mainly derived from pyrogenic sources rather than petrogenic sources. Traffic emissions (e.g., vehicle exhaust, tire debris, and possible leaks of fuels, oils, and lubricants) were estimated as principal sources of PAHs and Me-PAHs, especially in the urban and industrial areas. Other pyrogenic sources (e.g., coal, wood, and biomass combustion) were also existed in the industrial, suburban, and rural areas, reflecting PAH origins from thermal industrial processes, open burning of agricultural by-products, and domestic energy utilization. Persons working outdoors and children in the urban and industrial areas were estimated to receive higher intake doses of PAHs and Me-PAHs, which were one to two orders of magnitude higher than those estimated for other groups. Except for potential cancer risk estimated for the occupational groups in the industrial area under the worst exposure scenarios, the non-cancer and cancer risk levels were generally acceptable; however, more comprehensive risk assessment considering other exposure pathways (e.g., inhalation and diet) is needed.

Dermal bioaccessibility of plasticizers in indoor dust and clothing

Several studies indicate that human exposure to plasticizers via dermal pathway is not negligible, but the dermal bioaccessibility of phthalates and alternative plasticizers from the important environmental matrix including indoor dust and clothing and the importance weight of dermal exposure to those pollutants have been poorly studied. An in vitro physiologically based extraction test was employed to investigate the dermal bioaccessibility of target phthalates and alternative plasticizers from indoor dust and clothing. Temperature, incubation time, sweat/sebum ratio and solid/liquid ratio were selected to study their effects on the bioaccessibility. The bioaccessibility of Diethyl phthalates (DEP), dibutyl phthalate (DBP), bis-2-ethylhexyl phthalate (DEHP), Acetyl tributyl citrate (ATBC), bis-2-ethylhexyladipate (DEHA) and bis-2-ethylhexyl terephthalate (DEHT) in indoor dust were 66.20 ± 1.93%, 94.27 ± 1.31%, 80.37 ± 8.09%, 75.02 ± 2.12%, 94.50 ± 3.42% and 74.09 ± 3.79%, respectively, under the condition of 1:1 sweat/sebum ratio, 1/100 solid/liquid ratio (indoor dust), 1:1 area/area ratio (1:1, clothing) and 90 min incubation time at 36.3 °C which are chosen based on the experimental results and human physical conditions. DBP showed the highest bioaccessibility in all samples. The time course of the plasticizer release was fitted to a first-order one-compartment model. DBP showed the highest release rate (k₁) calculated from the model, which was consistent with the bioaccessibility result. Risk assessment indicated that dermal exposure of DBP was an important exposure route, accounting for about 21.58% of total intake, and indoor dust was an important exposure media when considering the dermal bioaccessibility.

Polycyclic aromatic hydrocarbons and their methylated derivatives in settled dusts from end-of-life vehicle processing, urban, and rural areas, northern Vietnam: Occurrence, source apportionment, and risk assessment

The occurrence and profiles of 19 polycyclic aromatic hydrocarbons (PAHs) and 15 methylated derivatives (Me-PAHs) were examined in settled dust samples collected from workplaces and living areas of an informal end-of-life vehicle (ELV) processing village, and house dusts from urban and rural areas in northern Vietnam. Concentrations of total PAHs and Me-PAHs decreased in the order: ELV workplace (median 5700, range 900-18,000 ng g^-1) > rural house (3700, 1800-6200 ng g^-1) > urban house (1800, 620-3100 ng g^-1) ≈ ELV living dusts (1000, 600-3900 ng g^-1). PAHs with 4 rings or more dominated in almost all the samples, indicating the abundance of pyrogenic sources (e.g., vehicular emissions and domestic thermal processes). Levels of Me-PAHs were exceeded those of PAHs in several ELV samples, revealing specific petrogenic sources derived from vehicle processing activities. Results from source apportionment analysis have partially identified traffic emission, biomass and coal combustion, and mixed petrogenic-pyrogenic sources related to ELV waste as the major sources of PAHs and Me-PAHs in the urban, rural, and ELV areas, respectively. Daily intake doses and health risk related to PAHs and Me-PAHs in settled dusts were estimated for ELV workers and residents living in the study areas. The worst exposure scenario of dust-bound PAHs showed a potential cancer risk for the ELV workers, meanwhile, no significant non-cancer and cancer risk was expected for other exposed groups. A more comprehensive and accurate risk assessment of PAHs and related compounds should be conducted in Vietnam.

Ingestion bioaccessibility of indoor dust-bound PAHs: Inclusion of a sorption sink to simulate passive transfer across the small intestine

In this study, we investigated the levels of 12 priority polycyclic aromatic hydrocarbons (PAH₁₂) pollutants, bioaccessible PAH₁₂, and sorption sink for PAH₁₂ by a silicone sheet of indoor dust samples, which were collected from teachers' offices (n = 17), students' offices (n = 17), laboratory (n = 11), and experimental center (n = 9), using an in vitro digestive model. In PAH₁₂, bioaccessible PAH₁₂, and sorption sink PAH₁₂, benzo[b]fluoranthene (BbF), phenanthrenes (Phe), and fluoranthene (FLA) were labeled respectively the most significant PAHs (6.61 ± 4.42 μg/g, 0.16 ± 0.11 μg/g, and 0.08 ± 0.06 μg/g) after indoor dust ingestion, whereas the proportions of anthracene (Ant), benzo(g,h,i)perylene (BghiP), and BghiP (0.34 ± 0.17, 0.03 ± 0.03 and 0.01 ± 0.01 μg/g) were low. Based on benzo[a]pyrene- equivalent carcinogenic concentrations, the mean daily exposure of bioaccessible PAH₁₂ and sorption sink for PAH₁₂ by indoor dust ingestion was 4.07 × 10^-3 ± 1.73 × 10^-3 and 3.23 × 10^-3 ± 1.36 × 10^-3 μg/day in the experimental center; 4.01 × 10^-3 ± 2.05 × 10^-3 and 1.46 × 10^-3 ± 6.72 × 10^-4 μg/day in students' offices; 8.25 × 10^-4 ± 2.33 × 10^-4 and 5.15 × 10^-4 ± 1.37 × 10^-4 μg/day in laboratory; and 7.05 × 10^-4 ± 4.12 × 10^-5 and 2.82 × 10^-4 ± 4.36 × 10^-5 μg/day in teachers' offices, respectively. Our results indicated that the passive transfer fraction of PAH₁₂ (44.07%-67.36% in this case) is therefore large and needs to be considered in exposure and risk assessments.

Occurrence of legacy and alternative plasticizers in indoor dust from various EU countries and implications for human exposure via dust ingestion and dermal absorption

Plasticizers are a category of chemicals extensively used in consumer products and, consequently, their presence is ubiquitous in the indoor environment. In the present study, an analytical method has been developed for the quantification of plasticizers (7 legacy phthalate esters (LPEs) and 14 alternative plasticizers (APs)) in indoor floor dust based on ultrasonic and vortex extraction, Florisil fractionation and GC-(EI)-MS analysis. Dust samples (n = 54) were collected from homes, offices, and daycare centers from different EU countries (Belgium, the Netherlands, Ireland and Sweden). Method LOQs ranged from 0.2 to 5 μg/g. Tri-n-hexyl trimellitate (THTM) was not detected in any sample, whereas dimethyl phthalate (DMP), diphenyl phthalate and acetyl triethyl citrate (ATEC) were detected only in 6, 2 and 1 out of 54 samples, respectively. The highest concentrations of plasticizers were measured in Swedish offices, at a mean concentration of total plasticizers of 1800 μg/g, followed by Swedish daycare centers at 1200 and 670 μg/g for winter and spring sampling, respectively. Generally, the contribution of APs was slightly higher than for LPEs for all indoor environments (mean contribution 60% and 40%, respectively based on contributions per indoor environment). For the APs, main contributors were DINP in Belgian homes (28%), Swedish offices (60%), Swedish daycare centers (48%), and Dutch offices (31%) and DEHT in Belgian (28%), Irish (40%) and Dutch homes (37%) of total APs. The predominant LPE was bis-2-ethylhexyl-phthalate (DEHP) with a mean contribution varying from 60% to 85% of total LPEs. Human exposure was evaluated for dust ingestion and dermal absorption using hazard quotients (HQs) of plasticizers (ratio between average daily doses and the reference dose). None of the HQs of plasticizers exceeded 1, meaning that the risk for adverse human health effects from these plasticizers via dust ingestion and dermal absorption is unlikely.

Comparison of sorption kinetics of PAHs by sorptive sinks and caco-2 cell and the correlation between bioaccessibility and bioavailability of PAHs in indoor dust

Sorptive sinks are extensively used in the bioaccessibility of organic contaminants, but their suitability for simulating the intestinal cell is seldom reported. In the present study, the sorption efficiency of PAHs by sorptive sinks including silica, poly(ethylene-co-vinyl acetate) (polyE), tenax, and C18 were compared with that by caco-2 cells. The elimination rate constants of phenanthrene, fluoranthene, pyrene, benzo(a)pyrene by caco-2 cell were 0.0417 ± 0.006 min^-1, 0.0411 ± 0.0074 min^-1, 0.0362 ± 0.006 min^-1, and 0.0526 ± 0.0037 min^-1, respectively, which were more closely to that of silica and polyE compared to other materials. This indicated that these materials might be the preferable sorptive sinks to simulate absorption of PAHs by intestinal cells. The bioaccessibility of phenanthrene, fluoranthene, pyrene, benzo(a)pyrene in indoor dust ranged from 15.5-43.5%, 9.10-38.8%, 10.0-37.9%, and 6.00-21.9%, respectively, based on physiologically based extraction test (PBET) and the sorptive sinks added in the intestinal solution led to 1.17 to 8.47-fold enhancement of bioaccessibility. The correlation of in vivo PAHs relative bioavailability (RBA) and in vitro digestion bioaccessibility with or without the sorptive sinks of indoor dust were measured, and the results indicated that silica and polyE were more likely to predict PAHs RBA of indoor dust, which was consistent with the results of sorption kinetics assay. The present results indicate that silica and polyE have the potential to simulate caco-2 cell and the inclusion of these materials in the PBET is likely to predict PAHs RBA in indoor dust. Capsule: Silica and polyE were more likely to simulate absorption of PAHs by intestinal cells, and to predict PAHs RBA of indoor dust.

Oral bioaccessibility of semi-volatile organic compounds (SVOCs) in settled dust: A review of measurement methods, data and influencing factors

Many semi-volatile organic compounds (SVOCs), suspected of reprotoxic, neurotoxic or carcinogenic effects, were measured in indoor settled dust. Dust ingestion is a non-negligible pathway of exposure to some of these SVOCs, and an accurate knowledge of the real exposure is necessary for a better evaluation of health risks. To this end, the bioaccessibility of SVOCs in dust needs to be considered. In the present work, bioaccessibility measurement methods, SVOCs' oral bioaccessibility data and influencing factors were reviewed. SVOC bioaccessibilities (%) ranged from 11 to 94, 8 to 100, 3 to 92, 1 to 81, 6 to 52, and 2 to 17, for brominated flame retardants, organophosphorus flame retardants, polychlorobiphenyls, phthalates, pesticides and polycyclic aromatic hydrocarbons, respectively. Measurements method produced varying results depending on the inclusion of food and/or sink in the model. Characteristics of dust, e.g., organic matter content and particle size, also influenced bioaccessibility data. Last, results were influenced by SVOC properties, such as octanol/water partition coefficient and migration pathway into dust. Factors related to dust and SVOCs could be used in prediction models. To this end, more bioaccessibility studies covering more substances should be performed, using methods that are harmonized and validated by comparison to in-vivo studies.

Characteristics and health risk assessment of heavy metals exposure via household dust from urban area in Chengdu, China

To investigate the characteristics of heavy metals (Cr, Cd, Pb, Zn, Cu and Ni) in household dust in urban household environment of Chengdu, China, 90 household dust samples were collected from 6 districts of the city. The information of houses and residents were also recorded during dust sampling to identify the correlations between heavy metals in household dust and the house attributes. And also the principal component analysis and cluster analysis for sources and impactor factors. The concentrations of Pb (123mg·kg^-1), Zn (675mg·kg^-1), Cu (190mg·kg^-1), Cr (82.7mg·kg^-1), Cd (2.37mg·kg^-1) and Ni (52.6mg·kg^-1) in household dust are in low or moderate levels when compare with that from other counties or areas. The heavy metals of household dust samples from Chengdu is higher concentrations than that in the street dust from Chengdu, except for Cr. Statistical analysis result showed traffic sources and corrosion of alloys are important factors contributing to the rise concentrations of heavy metals in household dust. In addition, there is negative correlation (p<0.05) between the heavy metals concentrations and floor levels. The ingestion is the important pathway for Pb, Zn, Cu and Ni via household dust exposure to the residents, and the dermal contact was identified as a main route for Cr and Cd in household dust exposure to the residents. There are minor non-carcinogenic and carcinogenic risks from the heavy metals in household dust for the residents in Chengdu.

Potentially harmful elements in house dust from Estarreja, Portugal: characterization and genotoxicity of the bioaccessible fraction

Due to their behavioral characteristics, young children are vulnerable to the ingestion of indoor dust, often contaminated with chemicals that are potentially harmful. Exposure to potentially harmful elements (PHEs) is currently exacerbated by their widespread use in several industrial, agricultural, domestic and technological applications. PHEs cause adverse health effects on immune and nervous systems and can lead to cancer development via genotoxic mechanisms. The present study is an integrated approach that aims at assessing the genotoxicity of bioaccessible PHEs following ingestion of contaminated house dust. A multidisciplinary methodology associating chemical characterization of five house dust samples, extraction of the bioaccessible PHEs in gastric extracts by the unified BARGE method, determination of the bioaccessible fraction and in vitro genotoxicity of gastric extracts in adenocarcinoma gastric human (AGS) cells was developed. The five gastric extracts induced dose-dependent genotoxicity in AGS cells. Copper (bioaccessible concentration up to 111 mg/kg) was probably the prevalent PHE inducing primary DNA damage (up to 5.1-fold increase in tail DNA at 0.53 g/l of gastric extract). Lead (bioaccessible concentration up to 245 mg/kg) was the most prevalent PHE inducing chromosome-damaging effects (r = 0.55; p < 0.001 for micronucleated cells induction). The association of principal component analysis and Spearman's correlations was decisive to understand the chromosome-damaging properties of the bioaccessible PHEs in AGS cells. This methodology could be used on a larger-scale study to provide useful information for science-based decision-making in regulatory policies, and a better estimation of human exposure and associated health risks.

Risk assessment of PBDEs and PAHs in house dust in Kocaeli, Turkey: levels and sources

Indoor dust samples were collected from 40 homes in Kocaeli, Turkey and were analyzed simultaneously for 14 polybrominated diphenyl ethers (PBDEs) and 16 poly aromatic hydrocarbons (PAHs) isomers. The total concentrations of PBDEs (Σ₁₄PBDEs) ranged from 29.32 to 4790 ng g^-1, with a median of 316.1 ng g^-1, while the total indoor dust concentrations of 16 PAHs (Σ₁₆PAHs) extending over three to four orders of magnitude ranged from 85.91 to 40,359 ng g^-1 with a median value of 2489 ng g^-1. Although deca-PBDE products (BDE-209) were the principal source of PBDEs contamination in the homes (median, 138.3 ng g^-1), the correlation in the homes was indicative of similar sources for both the commercial penta and deca-PBDE formulas. The PAHs diagnostic ratios indicated that the main sources of PAHs measured in the indoor samples could be coal/biomass combustion, smoking, and cooking emissions. For children and adults, the contributions to ∑₁₄PBDEs exposure were approximately 93 and 25 % for the ingestion of indoor dust, and 7 and 75 % for dermal contact. Exposure to ∑₁₆PAHs through dermal contact was the dominant route for both children (90.6 %) and adults (99.7 %). For both groups, exposure by way of inhalation of indoor dust contaminated with PBDEs and PAHs was negligible. The hazard index (HI) values for BDE-47, BDE-99, BDE-153, and BDE-209 were lower than the safe limit of 1, and this result suggested that none of the population groups would be likely to experience potential health risk due to exposure to PBDEs from indoor dust in the study area. Considering only ingestion + dermal contact, the carcinogenic risk levels of both B2 PAHs and BDE-209 for adults were 6.2 × 10^-5 in the US EPA safe limit range while those for children were 5.6 × 10^-4 and slightly higher than the US EPA safe limit range (1 × 10^-6 and 1 × 10^-4). Certain precautions should be considered for children.

In vitro digestion and absorption of BDE-28, -47, -99 and -153 in indoor dust and its implication in risk assessment

The bioaccessibility of polybrominated diphenyl ethers (PBDEs) in indoor dust was estimated by a series of in vitro digestion methods. However, the absorption of PBDEs by intestinal cells after in vitro digestion was seldom studied. In the present study, the bioaccessibility of BDE-28, 47, 99 and 153 in indoor dust was firstly investigated by using the in vitro digestion method. Bioaccessibility in intestinal phase (BDE-28: 24.5-30.1%; BDE-47: 6.99-13.0; BDE-99: 1.61-14.2%; and BDE-153 5.97-24.4%.) was higher than that in gastric phase (BDE-28: 38.3-58.0; BDE-47: 9.62-30.9%; BDE-99: 9.71-24.3%; and BDE-153: 13.8-57.4%). The organic matter contents in indoor dust showed variable influence on the bioaccessibility of PBDEs. For the Caco-2 uptake assay, the BDE-28 showed greatest transport rate from medium to cell (K_mc: 0.525h^-1), followed by -47, -99 and -153. The K_mc of PBDEs was significantly negative correlated with its corresponding K_OW value. Similar pattern was found for the maximum uptake flux (J_{u, max}) and the transport rate from cell to medium (K_cm). The combination of bioacessibility and the absorption factor by Caco-2 cells could be used to estimate human intake of PBDEs via indoor dust would avoid overestimate the health risk.

A review of heavy metals in indoor dust and its human health-risk implications

Indoor dust acts as a media for heavy metal deposition. Past studies have shown that heavy metal concentration in indoor dust is affected by local human activities and atmospheric transport can have harmful effects on human health. Additionally, children are more sensitive to heavy metals due to their hand-to-mouth behaviour and rapid body development. However, limited information on health risks were found in past dust studies as these studies aimed to identify heavy metal concentrations and sources of indoor dust. The objective of this review is to discuss heavy metal concentration and sources influencing its concentration in indoor dust. Accordingly, high lead (Pb) concentration (639.10 μg/g) has been reported in heavy traffic areas. In addition, this review paper aims to estimate the health risk to children from heavy metals in indoor dust via multiple exposure pathways using the health-risk assessment (HRA). Urban areas and industrial sites have revealed high heavy metal concentration in comparison to rural areas. Hazard index (HI) values found in arsenic (As), chromium (Cr) and Pb were 21.30, 1.10 and 2.40, respectively, indicate that non-carcinogenic elements are found in children. Furthermore, most of the past studies have found that carcinogenic risks for As, cadmium (Cd), Cr and Pb were below the acceptable total lifetime cancer risk (TLCR) range (1×10-6-1×10-4). The results of health risk assessment in this review show that carcinogenic risk exists among children. Hence, this proves that future studies need to focus on children's carcinogenic risk in indoor dust studies in order to find out the sources of heavy metals in indoor dust. This review highlights the importance of having the HRA application using bioavailable heavy metal concentration as it provides more accurate health-risk estimation. Moreover, this review is also useful as a reference for policy decision making in protecting children's health.

Polycyclic aromatic hydrocarbons and trace metals in mosque's carpet dust of Riyadh, Saudi Arabia, and their health risk implications

The main objectives of this work were to identify and determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) and trace metals in carpet dust samples from various mosques of the city of Riyadh and to assess the health risks associated with the exposure to these pollutants. Therefore, 31 samples of mosque's carpet dust from Riyadh were collected. The results showed that 14 PAHs were present in the dust samples with concentrations ranged from 90 to 22,146 ng g^-1 (mean = 4096 ± 4277 ng g^-1) where low molecular weight compounds were dominant. The presence of PAHs were in the order of naphthalene > chrysene and benzo(b)fluoranthene > benzo(a)pyrene > acenaphthene and benzo(k)fluoranthene > pyrene and the absence of indeno(1,2,3-cd)pyrene and dibenz(a,h)anthracene. The diagnostic ratio coupled with principle component analysis (PCA) revealed mix sources of petrogenic from traffic, stack emission, and pyrogenic inputs from essence and perfumed wood burning. Trace metals were significant in the dust samples, and their concentrations decrease in the order of Zn, Mn, Cu, Cr, Pb, Ni, and V where Zn being the highest (94.4 ± 91.5 μg g^-1) and indium was the lowest (1.9 ± 9.3 μg g^-1). The trace metals were major in southern and central parts of Riyadh and followed the order of central Riyadh > southern Riyadh > western Riyadh > eastern Riyadh > northern Riyadh. Estimated risk based on the total PAHs was found to be 4.30 × 10^-11 for adult and 1.56 × 10^-11 for children. Elemental non-cancer risk for adults ranged from 7.9 × 10^-4 for Co to 7.58 × 10^-1 for Li and for children ranged from 3.70 × 10^-3 for Co to 3.54 for Li. Policy implication and mitigations of PAHs in Riyadh and Saudi Arabia were highlighted.

Assessment of relative bioavailability of heavy metals in soil using in vivo mouse model and its implication for risk assessment compared with bioaccessibility using in vitro assay

There is limited study to simultaneously determine the relative bioavailability of heavy metals such as Cd, Pb, Cu, Cr(VI), and Ni in soil samples. In the present study, the bioaccessibility of heavy metals using in vitro assay was compared with the relative bioavailability of heavy metals using in vivo mouse model. The bioaccessibility of heavy metals ranged from 9.05 ± 0.97 % (Cr) to 42.8 ± 3.52 % (Cd). The uptake profile of heavy metals in soil and solution samples in mouse revealed that the uptake kinetics could be fitted to a two-compartment model. The relative bioavailability of heavy meals ranged from 34.8 ± 7.0 % (Ni) to 131 ± 20.3 % (Cu). Poor correlation between bioaccessibility and relative bioavailability of heavy metals was observed (r (2) = 0.11, p > 0.05). The relative bioavailability of heavy metals was significantly higher than the bioaccessibility of heavy metals (p < 0.05). The present study indicated that the in vitro digestion method should be carefully employed in risk assessment.

Molecular mechanisms of dust-induced toxicity in human corneal epithelial cells: Water and organic extract of office and house dust

Human corneal epithelial (HCE) cells are continually exposed to dust in the air, which may cause corneal epithelium damage. Both water and organic soluble contaminants in dust may contribute to cytotoxicity in HCE cells, however, the associated toxicity mechanisms are not fully elucidated. In this study, indoor dust from residential houses and commercial offices in Nanjing, China was collected and the effects of organic and water soluble fraction of dust on primary HCE cells were examined. The concentrations of heavy metals in the dust and dust extracts were determined by ICP-MS and PAHs by GC-MS, with office dust having greater concentrations of heavy metals and PAHs than house dust. Based on LC50, organic extract was more toxic than water extract, and office dust was more toxic than house dust. Accordingly, the organic extracts induced more ROS, malondialdehyde, and 8-Hydroxydeoxyguanosine and higher expression of inflammatory mediators (IL-1β, IL-6, and IL-8), and AhR inducible genes (CYP1A1, and CYP1B1) than water extracts (p<0.05). Extracts of office dust presented greater suppression of superoxide dismutase and catalase activity than those of house dust. In addition, exposure to dust extracts activated NF-κB signal pathway except water extract of house dust. The results suggested that both water and organic soluble fractions of dust caused cytotoxicity, oxidative damage, inflammatory response, and activation of AhR inducible genes, with organic extracts having higher potential to induce adverse effects on primary HCE cells. The results based on primary HCE cells demonstrated the importance of reducing contaminants in indoor dust to reduce their adverse impacts on human eyes.

Advances in in vitro methods to evaluate oral bioaccessibility of PAHs and PBDEs in environmental matrices

Cleanup goals for sites contaminated with persistent organic pollutants (POPs) are often established based on total contaminant concentrations. However, mounting evidence suggests that understanding contaminant bioavailability in soils is necessary for accurate assessment of contaminant exposure to humans via oral ingestion pathway. Animal-based in vivo tests have been used to assess contaminant bioavailability in soils; however, due to ethical issues and cost, it is desirable to use in vitro assays as alternatives. Various in vitro methods have been developed, which simulate human gastrointestinal (GI) tract using different digestion fluids. These methods can be used to predict POP bioavailability in soils, foods, and indoor dust after showing good correlation with in vivo animal data. Here, five common in vitro methods are evaluated and compared using PAHs and PBDEs as an example of traditional and emerging POPs. Their applications and limitations are discussed while focusing on method improvements and future challenges to predict POP bioavailability in different matrices. The discussions should shed light for future research to accurately assess human exposure to POPs via oral ingestion pathway.

Spatiotemporal analysis and human exposure assessment on polycyclic aromatic hydrocarbons in indoor air, settled house dust, and diet: A review

This review summarizes the published literature on the presence of polycyclic aromatic hydrocarbons (PAH) in indoor air, settled house dust, and food, and highlights geographical and temporal trends in indoor PAH contamination. In both indoor air and dust, ΣPAH concentrations in North America have decreased over the past 30 years with a halving time of 6.7±1.9years in indoor air and 5.0±2.3 years in indoor dust. In contrast, indoor PAH concentrations in Asia have remained steady. Concentrations of ΣPAH in indoor air are significantly (p<0.01) higher in Asia than North America. In studies recording both vapor and particulate phases, the global average concentration in indoor air of ΣPAH excluding naphthalene is between 7 and 14,300 ng/m(3). Over a similar period, the average ΣPAH concentration in house dust ranges between 127 to 115,817ng/g. Indoor/outdoor ratios of atmospheric concentrations of ΣPAH have declined globally with a half-life of 6.3±2.3 years. While indoor/outdoor ratios for benzo[a]pyrene toxicity equivalents (BaPeq) declined in North America with a half-life of 12.2±3.2 years, no significant decline was observed when data from all regions were considered. Comparison of the global database, revealed that I/O ratios for ΣPAH (average=4.3±1.3), exceeded significantly those of BaPeq (average=1.7±0.4) in the same samples. The significant decline in global I/O ratios suggests that indoor sources of PAH have been controlled more effectively than outdoor sources. Moreover, the significantly higher I/O ratios for ΣPAH compared to BaPeq, imply that indoor sources of PAH emit proportionally more of the less carcinogenic PAH than outdoor sources. Dietary exposure to PAH ranges from 137 to 55,000 ng/day. Definitive spatiotemporal trends in dietary exposure were precluded due to relatively small number of relevant studies. However, although reported in only one study, PAH concentrations in Chinese diets exceeded those in diet from other parts of the world, a pattern consistent with the spatial trends observed for concentrations of PAH in indoor air. Evaluation of human exposure to ΣPAH via inhalation, dust and diet ingestion, suggests that while intake via diet and inhalation exceeds that via dust ingestion; all three pathways contribute and merit continued assessment.

Polychlorinated biphenyls and organochlorine pesticides in atmospheric particulate matter of Northern China: distribution, sources, and risk assessment

The objectives of this work are to track the contamination levels, distribution characteristics, and sources of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in atmospheric particulate matter (APM) of Northern China and to provide more comprehensive and fundamental data for risk assessment of organochlorine contaminants (OCs) in environments. Samples were extracted and purified by the microwave-assisted extraction and solid-phase extraction system, respectively. PCBs and OCPs were analyzed by gas chromatograph-mass spectrometer. The concentrations of ΣPCBs and ΣOCPs ranged from 0.73 to 112.65 ng/g and 0.14 to 34.73 ng/g, respectively. PCBs in atmospheric particulates collected from Shijiazhuang City had the highest concentration, whereas OCP congeners were at the relatively low levels. However, the highest concentration of OCPs occurred in Yongning City. The principal component analysis indicated that the predominant compositions of PCBs in most of samples were tetrachlorobiphenyl (Tetra-CB), pentachlorobiphenyl (Penta-CB), hexachlorobiphenyl (Hexa-CB), and heptachlorbiphenyl (Hepta-CB), while hexachlorocyclohexanes (HCHs), DDTs, chlordanes, and endosulfans were the dominant components of OCPs, which was attributed to their application characteristics. OCs in those particles were further used to assess a potential cancer risk to humans via ingestion, dermal contact, and inhalation. Cancer risk was evaluated in airborne particles caused by PCBs and OCPs. TEQPCBs values suggested that the representative areas were subject to different pollution degrees. However, the pollution of OCPs in certain areas should be a concern due to 41.6% of the high risk, which could pose a potential risk to organisms.

Concentration and transportation of heavy metals in vegetables and risk assessment of human exposure to bioaccessible heavy metals in soil near a waste-incinerator site, South China

There is limited study focusing on the bioaccumulation of heavy metals in vegetables and human exposure to bioaccessible heavy metals in soil. In the present study, heavy metal concentrations (Cr, Ni, Cu, Pb and Cd) were measured in five types of vegetables, soil, root, and settled air particle samples from two sites (at a domestic waste incinerator and at 20km away from the incinerator) in Guangzhou, South China. Heavy metal concentrations in soil were greater than those in aerial parts of vegetables and roots, which indicated that vegetables bioaccumulated low amount of heavy metals from soil. The similar pattern of heavy metal (Cr, Cd) was found in the settled air particle samples and aerial parts of vegetables from two sites, which may suggest that foliar uptake may be an important pathway of heavy metal from the environment to vegetables. The highest levels of heavy metals were found in leaf lettuce (125.52μg/g, dry weight) and bitter lettuce (71.2μg/g) for sites A and B, respectively, followed by bitter lettuce and leaf lettuce for sites A and B, respectively. Swamp morning glory accumulated the lowest amount of heavy metals (81.02μg/g for site A and 53.2μg/g for site B) at both sites. The bioaccessibility of heavy metals in soil ranged from Cr (2%) to Cu (71.78%). Risk assessment showed that Cd and Pb in soil samples resulted in the highest non-cancer risk and Cd would result in unacceptable cancer risk for children and risk. The non-dietary intake of soil was the most important exposure pathway, when the bioaccessibility of heavy metals was taken into account.

Cancer risk assessment of human exposure to polycyclic aromatic hydrocarbons (PAHs) via indoor and outdoor dust based on probit model

In the present study, the polycyclic aromatic hydrocarbons (PAHs) in indoor dust and outdoor dust including road and window dust around the traffic road in Hunan Province, China, were sampled and detected. The ∑PAHs in indoor dust ranged from 5007-24,236 ng g(-1), with a median of 14,049 ng g(-1). The ∑PAHs in road dust ranged from 3644-12,875 ng g(-1), with a median of 10,559 ng g(-1). The ∑PAHs in window dust ranged from 803-12,590 ng g(-1), with a median of 5459 ng g(-1). Similar pattern of PAHs was observed in road and window dust except in H3W and H4W samples, which was dominated by naphthalene (Nap), benzo(b+k)fluoranthene (B(b+k)F), phenanthrene (Phe), and fluorine (Fle). Indoor dust showed slightly different PAHs profiles, which was dominated by Nap, fluoranthene (Fla) and Phe. Risk assessment indicated that dermal contact and dust ingestion exposure pathways were more important than the inhalation pathway. Cancer risk of PAHs via dust varied from 2.73 × 10(-8)-8.04 × 10(-6), with a median of 2.06 × 10(-6) for children, and from 2 × 10(-8)-5.89 × 10(-6), with a median of 1.52 × 10(-6) for adult. Probit model showed that 76 and 71 % of samples in the sampling area would result in the risk of children and adult exposure to PAHs via dust higher than the acceptable level (1 × 10(-6)), respectively.

Polycyclic aromatic hydrocarbons in deposited bedroom dust collected from Xinxiang, a fast developing city in North China

To investigate the contamination levels of polycyclic aromatic hydrocarbons (PAHs) in the indoor environment, 16 PAHs were measured in 20 deposited bedroom dust (DBD) samples collected from four residential areas in Xinxiang City. The total PAH concentrations (∑PAHs, defined as the sum of 16 PAHs) in 20 DBD samples ranged from 1.47 to 21.8 μg/g dry weight. PAH ratios indicated that main sources of PAHs in most DBD samples were coal, grasses, and wood combustion. Correlation analysis showed that there were no significant positive correlations between ∑PAH concentrations in DBD and the number of family members or duration of residence. Analysis using the t test revealed that tobacco smoke was a source of PAHs in DBD and that an unattached kitchen may be a significant influencing factor related to PAHs in DBD collected from residential areas in Xinxiang City. Our results showed that the kitchen exhaust fan or hood had no significant influence on total PAHs in DBD, and there was no significant difference in ∑PAH concentrations in DBD in homes which used liquefied petroleum gas and those which used natural gas.

Contamination and risk assessment (based on bioaccessibility via ingestion and inhalation) of metal(loid)s in outdoor and indoor particles from urban centers of Guangzhou, China

Road dust, household air-conditioning (AC) filter dust and PM2.5 were collected to investigate the contamination of metal(loid)s (Cr, Mn, Ni, Cu, Zn, As, Cd, Sn, Sb, Hg and Pb) in outdoor and indoor urban environments of Guangzhou. Zinc was found to be the most abundant element in road dust and household PM2.5, while the concentration of Pb was the highest in AC filter dust. Enrichment factor (EF) was used to assess the influence of human activity on the contamination of these metal(loid)s. Ingestion and inhalation were the two exposure pathways applied for risk assessment. Physiologically based extraction test (PBET) was used to estimate the oral bioaccessibilities of metal(loid)s in road dust and AC filter dust. Respiratory bioaccessible fraction of metal(loid)s via household PM2.5 was extracted with lung simulating solution. Household AC filter dust was more hazardous to human health than road dust, especially to children. Arsenic was found to be the most risky element based on the risk assessment.

Risk assessments of PAHs and Hg exposure via settled house dust and street dust, linking with their correlations in human hair

Domestic energy, chemicals bioaccessibility and particle size were found as three critical factors for risk assessment of PAHs exposure via settled house dust (SHD) and street dust. ∑PAHs and Hg contained in SHD were significantly (p<0.01) higher in coal-burning households of Qingyang (8.45-121; 0.48-16.4 μg g(-1)) than households in Guangzhou (1.23-22.2; 0.004-10.6 μg g(-1)) and 90% coal-burning houses were estimated with unacceptable cancer risks (>10(-4)) via SHD exposure. The highest accumulation trend of PAHs and Hg were found in <63 μm particles, and different particle sizes resulted in large variations of the obtained risks (up to 10 fold). Bioaccessibility corrected PAHs led to a significant decrease on related cancer risks and decreased in the order of 1.9, 1.1, 0.6 and 0.4 μg g(-1) with the increase of particle sizes (<63, 63-100, 100-280, 280-2000 μm). Scalp hair was tested as an indicator of body burdens of PAHs (0.05-0.9 μg g(-1)) and Hg (0.04-1.6 μg g(-1)). Different PAHs profiles were found between PAHs in SHD and those of hair, indicating that exogenous exposure to PAHs adsorbed on dust was not the major source of hair PAHs.

Bioaccessibility of polychlorinated biphenyls in workplace dust and its implication for risk assessment

Human exposure to bioaccessible PCBs via indoor dust is limited around the world. In the present study, the workplace dust sample from commercial office, hospital, secondary school, shopping mall, electronic factory and manufacturing plant were collected from Hong Kong for PCBs analyses. Total PCBs concentrations ranged from 46.8 to 249 ng g(-1), with a median of 107 ng g(-1). Manufacturing plant showed the highest concentration among all of sampling sites. PCB 77 was found as the dominant congeners. The bioaccessibility of PCBs in small intestinal juice ranging from 8.3% to 26.0% was significantly higher than that in gastric condition, ranging from 4.8% to 12.4%. In addition, significant negative correlations (p<0.05) were observed between KOW and bioaccessibility for all workplace dust samples. Risk assessment indicated that the averaged daily dose of dioxin-like PCBs via non-dietary intake of workplace dust, considering the bioaccessibility of PCBs, were much lower than the TDI of dioxins (2.3 pg WHO-TEQ kgbw(-1)d(-1)) established by Joint FAO/WHO Expert Committee on Food Additives.

Attic dust assessment near a wood treatment plant: past air pollution and potential exposure

The wood treatment process uses substances that generate hazardous compounds that may contaminate environmental compartments. In the present study, an area under influence of a deactivated wood treatment plant was investigated to evaluate past air pollution and to try to understand local air dispersion. Attic dust samples were collected from eight residences around the plant and from two residences outside this area, as reference samples. The presence of copper, chromium, arsenic, pentachlorophenol, sixteen priority polycyclic aromatic hydrocarbons and mutagenic activity using Salmonella/microsome assay was evaluated. The residences close to the entrance to the plant were the most affected, according to potentially toxic elements analysis. The PCP concentration was 0.49 mg/kg and the total PAHs content ranged from 0.40 to 13.31 μg/g with greater dispersion than potentially toxic elements. The highest mutagenesis values were 15,905 and 10,399 revertants/g of dust in the absence and presence of S9 mix (mammalian metabolic activation), respectively. Samples in which the total PAHs concentration was less than 2 μg/g no mutagenic effects were observed, including the residences in the reference area. The contribution of PAHs to mutagenesis was 10 percent, indicating that other compounds may contribute to the mutagenic effect. These results suggest that the population was or is potentially exposed to substances with strong effects on health.

Soil mutagenicity as a strategy to evaluate environmental and health risks in a contaminated area

Soil can be a storage place and source of pollutants for interfacial environments. This study looked at a site contaminated with wood preservatives as a source of mutagens, defined routes and extent of the dispersion of these contaminants by particle remobilization and atmospheric deposition, considering an evaluation of risk to human health by quantifying mutagenic risk. Soil sampling sites were chosen at gradually increasing distances (150, 500 and 1700m) from SI (industrial area pool) and indoor dust (pool in an area at risk at 385m and at 1700m). Mutagenesis was evaluated in the Salmonella/microsome assay, TA98, TA97a and TA100 strains with and without S9 mix, YGs strains 1041, 1042 and 1024 for nitrocompounds. Acid extracts were analyzed to define the effects of metals and organics for polycyclic aromatic hydrocarbons (PAHs) and nitroderivates, besides concentrations of these compounds and pentachlorophenol (PCP). Risk to human health was obtained from the relation between the quantified potential of mutagenic risk and estimated soil ingestion for children according to USEPA. Metal concentrations showed a gradient of responses with As, Cr and Cu (total metal) or Cr and Cu (fraction available) higher for SI. However, mutagenic effects of the mixtures did not show this grading. Site SR1700, without a response, was characterized as a reference. In organic extracts, the mutagenesis responses showed the mobility of these compounds from the source. In the surrounding area, a smaller pattern similar to SI was observed at SR150, and at the other sites elevated values of direct mutagenesis at SR500 and diminished effects at SR1700. Tests with YG strains indicated that nitrated compounds have a significant effect on the direct mutagenesis found, except SR500. The investigation of indoor dust in the surrounding area enabled confirmation of the particle resuspension route and atmospheric deposition, showing responses in mutagenicity biomarkers, PAH concentrations and PCP dosage similar to SI. The range of values obtained, considering the soil masses needed to induce mutagenicity was 0.02 to 0.33g, indicating a high risk associated with human populations exposed, since these values found surpass the standard estimate of 200mg/day of rate of soil ingestion for children according to USEPA. The study showed that it is essential to evaluate the extent of contamination from the soil to delimit remedial measures and avoid damage to the ecological balance and to human health.

Risk assessment of human exposure to bioaccessible phthalate esters via indoor dust around the Pearl River Delta

There is limited information on the bioaccessible fractions of phthalate esters in indoor dust in order to estimate human exposure. In the present study, workplace dust and settled house dust samples from Hong Kong, Shenzhen, and Guangzhou, the three major cities scattered around the Pearl River Delta (PRD) were collected. Chemical analyses showed that the phthalates in workplace dust ranged from 144 to 1810 μg/g, with dust from shopping malls containing the highest level, and in home dust ranged from 181 to 9240 μg/g. The most abundant phthalate ester found was bis(2-ethylhexyl) phthalate (DEHP) in both workplace dust and home dust, followed by di-n-butyl phthalate (DBP) and di-iso-butyl phthalate (DIBP). Principal Components Analysis (PCA) indicated that indoor dust around PRD showed similar phthalate esters patterns of composition. A significant correlation was observed between total phthalate esters concentrations in home dust and the number of year of house construction (p < 0.05). The oral bioaccessibility of phthalate esters in indoor dust ranged from 10.2% (DEHP) to 32% (DMP). Risk assessment indicated that the dominant exposure routes varied in different phthalate esters exposure profiles and the dermal contact exposure pathway was identified as an important route for indoor DEHP exposure.