Incidental Soil Research Articles

Application and demonstration of meso-activity exposure factors to advance estimates of incidental soil ingestion among agricultural workers.

Soil is an understudied and underregulated pathway of chemical exposure, particularly for agricultural workers who cultivate food in soils. Little is known about how agricultural workers spend their time and how they may contact soil while growing food. Exposure factors are behavioral and environmental variables used in exposure estimation. Our study aimed to derive exposure factors describing how growers engage in different tasks and use those factors to advance the use of time-activity data to estimate soil ingestion exposures among agricultural workers. We administered a meso-activity-based, season-specific soil contact activity questionnaire to 38 fruit and vegetable growers. We asked growers to estimate the frequency and duration of six meso-activities and describe how they completed them. We used questionnaire data to derive exposure factors and estimate empirical and simulated exposures to a hypothetical contaminant in soil via incidental ingestion using daily, hourly, and hourly-task-specific ingestion rates. We generated exposure factors characterizing the frequency and duration of six meso-activities by season, and self-reported soil contact, glove use, and handwashing practices by meso-activity and season. Seasonal average daily doses (ADDs) were similar across all three forms of ingestion rates. No consistent patterns regarding task-specific contributions to seasonal or annual ADDs were observed.

Concentrations of Lead and Arsenic in Mother's Milk and Children's Blood in Peruvian Breastfeeding Dyads.

Toxic trace elements could enter human milk through mothers' food consumption, drinking water, air, or incidental soil ingestion, and are of concern to the nursing infant. To determine the concentration of toxic trace elements (lead and arsenic) in Peruvian mothers' milk and their association with blood concentrations in their own infants 3-20 months old. This exploratory, cross-sectional study, carried out in Peru, included breastfeeding mother/child dyads (N = 40). Following standardized protocols, biospecimens of human milk and child's blood were collected. Lead and arsenic concentrations in milk were above the method detection limits in 73% and 100% of samples with median concentrations of 0.26 µg/L (IQR = 0.10, 0.33 µg/L) and 0.73 µg/L (IQR = 0.63, 0.91 µg/L), respectively. Concentrations of lead and arsenic in blood were 2.05 µg/dL (SD = 1.35), and 1.43 µg/dl (geometric mean: SD = 1.39), respectively. Blood lead concentrations in 12.5% (n = 5) of the samples were above the U.S. Center for Disease Control and Prevention reference value (< 3.5 µg/dl), and over half of arsenic concentrations were above the acceptable levels of < 1.3 µg/dl (Mayo Clinic Interpretative Handbook). Our results showed that for every one-month increase in age, lead blood concentrations increased by 0.1 µg/dl (p = 0.023). Additionally, every 1 µg/L increase in the mother's milk arsenic was associated with a 1.40 µg/dl increase in the child's blood arsenic concentration. Implementing effective interventions to decrease the toxic exposure of reproductive-aged women is needed in Peru and worldwide.

Priority Soil Pollution Management of Contaminated Site Based on Human Health Risk Assessment: A Case Study in Southwest China

The human risk assessment model can serve as a tool for regional contaminated site comprehensive management. However, site-specific risk assessment is still seldom applied in China as a basis for making decisions on risk management actions. In this study, a total of 112 soil samples were collected from ten polluted sites in Southwest China. The human health risk assessment method was used to assess the risk of Cd, As, Cu, Pb, Cr, Zn, and Hg pollution. According to the findings, the average concentrations of As, Zn, and Pb in contaminated sites are substantially higher than those of Cu, Cd, Cr, and Hg. Further studies conclusively showed the soil at contaminated site in its present condition pose risk to human health to potential future receptors. The main contribution of non-cancer and cancer risks was through incidental soil and dust ingestion. The priority control site remediation order is Region VI &gt; Region V &gt; Region IV &gt; Region III &gt; Region VII &gt; Region X &gt; Region IX &gt; Region VIII &gt; Region I &gt; Region II. Finally, management recommendations are made, including reducing pollutant intake, implementing a stringent monitoring scheme, utilizing bioremediation, and strengthening the implementation of relevant laws. This study provides a case for the comprehensive evaluation of soil pollution at contaminated sites in China.

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

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

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

BackgroundSoil and dust ingestion can be a primary route of environmental exposures. Studies have shown that young children are more vulnerable to incidental soil and dust ingestion. However, available data to develop soil and dust ingestion rates for some child-specific age groups are either lacking or uncertain.ObjectiveOur objective was to use the Stochastic Human Exposure and Dose Simulation Soil and Dust (SHEDS-Soil/Dust) model to estimate distributions of soil and dust ingestion rates for ten age ranges from infancy to late adolescents (birth to 21 years).MethodsWe developed approaches for modeling age groups previously not studied, including a new exposure scenario for infants to capture exposures to indoor dust via pacifier use and accounting for use of blankets that act as a barrier to soil and dust exposure.ResultsOverall mean soil and dust ingestion rates ranged from ~35 mg/day (infants, 0–<6 m) to ~60 mg/day (toddlers and young children, 6m–<11 yr) and were considerably lower (about 20 mg/day) for teenagers and late adolescents (16–<21 y). The pacifier use scenario contributed about 20 mg/day to the median dust ingestion rate for young infants. Except for the infant age groups, seasonal analysis showed that the modeled estimates of average summer mean daily total soil plus dust ingestion rates were about 50% higher than the values predicted for the winter months. Pacifier use factors and carpet dust loading values were drivers of exposure for infants and younger children. For older children, influential variables included carpet dust loading, soil adherence, and factors that capture the frequency and intensity of hand-to-mouth behaviors.SignificanceThese results provide modeled estimates of children’s soil and dust ingestion rates for use in decision making using real-world exposure considerations.Impact statementThe parameterization of scenarios to capture infant soil and dust ingestion and the application of SHEDS-Soil/Dust to a broader age range of children provides additional estimates of soil and dust ingestion rates that are useful in refining population-based risk assessments. These data illuminate drivers of exposure that are useful to both risk management applications and for designing future studies that improve upon existing tracer methodologies.

Terrestrial ecological risk analysis via dietary exposure at uranium mine sites in the Grand Canyon watershed (Arizona, USA)

The U.S. Department of the Interior recently included uranium (U) on a list of mineral commodities that are considered critical to economic and national security. The uses of U for commercial and residential energy production, defense applications, medical device technologies, and energy generation for space vehicles and satellites are known, but the environmental impacts of uranium extraction are not always well quantified. We conducted a screening-level ecological risk analysis based on exposure to mining-related elements via diets and incidental soil ingestion for terrestrial biota to provide context to chemical characterization and exposures at breccia pipe U mines in northern Arizona. Relative risks, calculated as hazard quotients (HQs), were generally low for all biological receptor models. Our models screened for risk to omnivores and insectivores (HQs>1) but not herbivores and carnivores. Uranium was not the driver of ecological risk; arsenic, cadmium, copper, and zinc were of concern for biota consuming ground-dwelling invertebrates. Invertebrate species composition should be considered when applying these models to other mining locations or future sampling at the breccia pipe mine sites. Dietary concentration thresholds (DCTs) were also calculated to understand food concentrations that may lead to ecological risk. The DCTs indicated that critical concentrations were not approached in our model scenarios, as evident in the very low HQs for most models. The DCTs may be used by natural resource and land managers as well as mine operators to screen or monitor for potential risk to terrestrial receptors as mine sites are developed and remediated in the future.

Feasibility of Metal(loid) Phytoextraction from Polluted Soils: The Need for Greater Scrutiny.

Feasibility of Metal(loid) Phytoextraction from Polluted Soils: The Need for Greater Scrutiny.

Human health risk assessment of metals exposure through subsistence foods consumption and subsistence harvest activities near a mining transport road in northwest Alaska

Historical transport of ore concentrate over a 50-mile haul road from the Red Dog zinc/lead mine in northwest Alaska to a seaport has been associated with elevated lead levels on moss growing near the road and with concerns about the safety of subsistence foods. As part of a comprehensive evaluation of potential impacts to human health and the environment from metals released during overland transport of ore concentrate, a human health risk assessment was conducted. Exposure to site-related metals through subsistence food consumption, water ingestion, and incidental soil ingestion was evaluated for three scenarios: child subsistence use, adult subsistence use, and adult combined occupational and subsistence use. The risk assessment used local subsistence food consumption data and subsistence harvest area information, along with metal concentrations from soil, water, caribou, fish, ptarmigan, berries, and sourdock collected on or near the road and port. The results, along with other lines of evidence, indicate that risks associated with subsistence food consumption and harvest activities are well within acceptable limits for each scenario and that subsistence foods remain safe to eat. Additionally, human health risks are not elevated even when data from restricted areas of the road and port are included.

Human Health Risk Assessment from the Consumption of Vegetables Grown near a Copper Smelter in Central Chile

The intake of trace elements (TEs) through the consumption of vegetables is a subject of great concern. This study intends to evaluate human health risks associated with consumption of vegetables grown near the Ventanas copper smelter (Valparaiso region, Central Chile). Experimental plots were established in the proximity of the smelter and in a control area. Leafy vegetables (lettuce, chard, and cabbage) and root vegetables (potato, carrot, and beetroot) were grown on the experimental plots. Daily intake of elements was estimated based on consumption habits. A hazard quotient (HQ) was calculated as a ratio between the daily intake and the reference dose that represents the maximum safe TE intake. Generally, concentrations of TEs in the edible tissues of vegetables were higher in the exposure area than in the control area. The most significant difference was for leafy vegetables, with arsenic (As) being the main TE of concern. Lettuce was also the vegetable of concern due to its relatively high consumption rate and a relatively high concentration of TEs in the plant tissue. In this study, we obtained an HQ value of ~ 0.6 for inorganic As considering vegetable consumption pathway, for the age group of 1–5 years old. Likewise, our previous study reported a similar HQ value of ~ 0.6 for inorganic As considering incidental soil and dust ingestion pathway, for the same age group. Importantly, HQ value surpasses 1.0 for inorganic As considering both exposure pathways. Thus, there is a health risk associated with soil As for inhabitants of Puchuncavi Valley.

The Influence of Food on the In Vivo Bioavailability of DDT and Its Metabolites in Soil.

Incidental soil ingestion is considered to be an important route of exposure to hydrophobic organic contaminants (HOCs), such as dichlorodiphenyl-trichloroethane (DDT). Contaminant ingestion often occurs during food consumption; however, knowledge on the influence of food on DDT bioavailability remains limited. In this study, the relative bioavailability (RBA) of soil DDTr (i.e., DDT and metabolites) was determined using an in vivo mouse model in the presence of eight kinds of food including rice, egg, pork, pear, soybean, bread, spinach, and milk powder. The values of DDTr-RBA ranged from 19.8 ± 10.9 to 114 ± 25.1%. DDTr-RBA was positively correlated with fat (r = 0.71) and negatively correlated with fiber (r = 0.63) content in food. A mechanistic study showed that fat enhanced micellarization and promoted the formation of chylomicron, which facilitated the dissolution and transport of DDTr in the intestinal tract. Bioaccessibility of DDTr was determined using a physiologically based in vitro method. The addition of lipase significantly improved the ability of the method to predict DDTr-RBA, indicating that the "fasted state" in vitro method required optimization for food scenarios. To the best of our knowledge, this is the first study to explore the mechanistic influence of food on DDTr-RBA and provide important knowledge on dietary approaches for reducing exposure to HOCs.

Ingestion and inhalation of metal(loid)s through preschool gardening: An exposure and risk assessment in legacy mining communities

Children residing in mining towns are potentially disproportionately exposed to metal(loid)s via ingestion and dust inhalation, thus, increasing their exposure when engaging in school or home gardening or playing outside. This citizen science study assessed preschool children’s potential arsenic (As), cadmium (Cd), and lead (Pb) exposure via locally grown produce, water, incidental soil ingestion, and dust inhalation at four sites. Participants were trained to properly collect water, soil, and vegetable samples from their preschools in Nevada County, California. As, Cd, and Pb concentrations in irrigation sources did not exceed the U.S. EPA’s maximum contaminant and action levels. In general, garden and playground As and Pb soil concentrations exceeded the U.S. EPA Regional Screening Level, CalEPA Human Health Screening Level, and California Department of Toxic Substances Control Screening Level. In contrast, all Cd concentrations were below these recommended screening levels. Dust samples (<10 μm diameter) were generated from surface garden and playground soil collected at the preschools by a technique that simulated windblown dust. Soil and dust samples were then analyzed by in-vitro bioaccessibility assays using synthetic lung and gastric fluids to estimate the bioaccessible fraction of As, Cd, and Pb in the body. Metal(loid) exposure via grown produce revealed that lettuce, carrot, and cabbage grown in the preschool gardens accumulated a higher concentration of metal(loid) than those store-bought nation-wide. None of the vegetables exceeded the respective recommendation maximum levels for Cd and Pb set by the World Health Organization Codex Alimentarius Commission. The results of this study indicate that consumption of preschool-grown produce and incidental soil ingestion were major contributors to preschool-aged children’s exposure to As, Cd, and Pb. Traditionally, this level of site- and age-specific assessment and analyses does not occur at contaminated sites. The results of this holistic risk assessment can inform future risk assessment and public health interventions related to childhood metal(loid) exposures.

Towards an exposure narrative for metals and arsenic in historically contaminated Ni refinery soils: Relationships between speciation, bioavailability, and bioaccessibility

Archived soils contaminated with Ni, Cu, Co, and As from legacy operations of a nickel refinery at Port Colborne, Ontario, Canada were speciated using mineral liberation analysis. Four Ni minerals were identified as fingerprint compounds of the historical refinery emissions. Cu and Co were present in solid solution in these minerals due to their presence in the refinery's feed. The highest concentrations of Ni, Cu, Co, and As in these soils were 18,553, 1915, 196, and 79mg/kg, respectively, these elevated contaminant concentrations attesting to the importance of incidental soil ingestion to the oral exposure pathway in Port Colborne. The in vitro gastric bioaccessibility (BAc) was determined for these contaminants, as was in vivo oral bioavailability (BAv), using a mass balance approach in male Sprague-Dawley rats. In spite of the elevated soil concentrations of Cu, the BAv of this physiologically important metal could not be distinguished from that in commercial rat chow, suggesting low potential for exposure. Co and As also had low apparent BAv (<2%). For Ni, baseline oral BAv of naturally sourced dietary Ni was found to be approximately 2%, as was the oral BAv of Ni from nickel sulfate hexahydrate. The mass balances of NiSO4·6H2O were fully accounted-for in urine and feces after a single gavage dose, indicating little to no organ incorporation from this highly soluble salt. Therefore, the urinary estimates of Ni BAv for these soils were assumed to represent true BAv despite variable fecal recoveries. The high Ni concentrations enabled BAc-BAv relationships to be developed for these contaminated soils. For absolute bioavailability (ABA) and relative bioavailability (RBA) the relationships were: ABA=0.0116(BAc)-0.0479 and RBA=0.5542(BAc)-2.2817. These findings will advance the development of robust exposure narratives for soil metal contamination in Port Colborne and elsewhere.

Understanding the Intrinsic and Extrinsic Motivations Associated with Community Gardening to Improve Environmental Public Health Prevention and Intervention.

Considering that community members continue to garden in and near environments impacted by pollutants known to negatively impact human health, this paper seeks to characterize the intrinsic and extrinsic motivations of a gardener and elucidate their perception of soil quality and environmental responsibility, awareness of past land use, and gardening behavior. Via semi-structured interviews with community gardeners in the Boston area (N = 17), multifactorial motivations associated with gardening as well as ongoing environmental health challenges were reported. Gardeners are knowledgeable about their garden’s historical past and are concerned with soil quality, theft, trash maintenance, animal waste, and loss of produce from foraging animals. Study findings directly inform the field of environmental health exposure assessments by reporting gardening duration, activities that can lead to incidental soil ingestion, and consumption patterns of locally grown produce. This information combined with an understanding of a gardener’s intrinsic and extrinsic motivations can be used to develop urban agricultural infrastructure and management strategies, educational programming, and place-based environmental public health interventions.

Using Sheds-S/D Model to Estimate Soil and Dust Ingestion Rates for Adults

Soil and dust ingestion is the primary pathway for environmental exposure to some pollutants. As is the case with children, incidental soil and dust ingestion rates for adults are dependent on the ...

Selective logging effects on ‘brown world’ faecal-detritus pathway in tropical forests: A case study from Amazonia using dung beetles

Abstract While a significant effort has been made to understand how human activities influence biodiversity, less attention has been given to the consequences of tropical forest disturbance on belowground functional processes and its linkages with environmental drivers. Here, we demonstrate how selective logging influenced dung beetle communities and two associated ecological processes – namely, dung consumption and incidental soil bioturbation – in the eastern Brazilian Amazon, using a robust before-and-after control-impact design. We tested hypotheses about logging-induced changes on environmental condition (canopy cover, leaf litter and soil texture), community metrics (e.g. dung beetle species richness and biomass) and beetle-mediated faecal-detritus processing; and on the importance of the environment for beetle communities and functional processes. We show that post-logging changes in canopy openness do not necessarily mediate logging impacts on dung beetle diversity and biomass, which were directly influenced by reduced impact logging (RIL) operations. Although neither environmental condition (leaf litter or soil sand content) nor faecal consumption and incidental soil bioturbation were directly affected by RIL, the relationships between environmental condition and biological components were. By showing that selective logging alters the linkages among belowground ecological processes and environmental drivers, we provide support that logged forests can retain some important functioning processes, in particular faecal consumption, even when the dung beetle diversity and biomass are impoverished. These results provide support for the resistance of functional processes to logging-induced changes in biodiversity.

Lead bioaccumulation in Texas Harvester Ants (Pogonomyrmex barbatus) and toxicological implications for Texas Horned Lizard (Phrynosoma cornutum) populations of Bexar County, Texas.

Uptake of lead from soil was examined in order to establish a site-specific ecological protective concentration level for the Texas Horned Lizard (Phrynosoma cornutum) at the Former Humble Refinery in San Antonio, Texas. Soils, harvester ants, and rinse water from the ants were analyzed at 11 Texas Harvester Ant (Pogonomyrmex barbatus) mounds. Soil concentrations at the harvester ant mounds ranged from 13 to 7474mg/kg of lead dry weight. Ant tissue sample concentrations ranged from < 0.82 to 21.17mg/kg dry weight. Rinse water concentrations were below the reporting limit in the majority of samples. Two uptake models were developed for the ants. A bioaccumulation factor model did not fit the data, as there was a strong decay in the calculated value with rising soil concentrations. A univariate natural log-transformed regression model produced a significant regression (p < .0001) with a high coefficient of determination (0.82), indicating a good fit to the data. Other diagnostic regression statistics indicated that the regression model could be reliably used to predict concentrations of lead in harvester ants from soil concentrations. Estimates of protective levels for P. cornutum were developed using published sub-chronic toxicological findings for the Western Fence Lizard that were allometricly adapted and compared to the Doseoral equation, which estimated lead consumed through ants plus incidental soil ingestion. The no observed adverse effect level toxicological limit for P. cornutum was estimated to be 5500mg/kg.

Characterization and geochemistry of technogenic magnetic particles (TMPs) in contaminated industrial soils: Assessing health risk via ingestion

The objective of this study was the detailed characterization of “technogenic” magnetic particles (TMPs) separated from contaminated industrial soils. Moreover, non-carcinogenic health risk posed by “technogenic” metals Pb and Zn via the ingestion exposure pathway was carried out. Volume magnetic susceptibility (κ) was measured directly in the field around a chemical industry in Sindos industrial area, Northern Greece. Representative soil samples were collected from the sites where elevated κ values were recorded. Mass specific magnetic susceptibility (χlf) depended on the content of TMPs and ranged from 52.6×10−8m3kg−1 to 821.2×10−8m3kg−1 with the maximum values detected in the immediate vicinity of the industrial unit where the most contaminated soils were also identified. Mineralogically the TMPs exhibited a dominant iron spinel phase, while other iron-bearing phases such as hematite and lepidocrocite were detected. Morphologically, Fe-rich spherules and irregular-shaped particles were the most commonly observed particles in TMPs, revealing various Fe contents often associated with elevated heavy metal contents. TMPs exhibited significantly higher concentrations of trace elements compared to non-magnetic fractions (NMFs) indicating that potentially harmful elements (PHEs) are preferentially enriched in the TMPs. Furthermore, for the first time, a health risk assessment study for the incidental soil magnetic fractions (MFs) ingestion of the “technogenic” metals Pb and Zn was carried out based on U.S. Environmental Protection Agency (U.S.E.P.A.) guidelines, incorporating oral bioaccessibility measurements using the BARGE Unified Bioaccessibility Method (UBM). Significant fractions (>50%) of Pb and Zn occur in bioaccessible forms in the TMPs and both children and adults are experiencing potential health risk since determined HQs values were significantly higher than safe level (=1).

Bioaccumulation and cancer risk of polycyclic aromatic hydrocarbons in leafy vegetables grown in soils within automobile repair complex and environ in Uyo, Nigeria.

Using gas chromatography-mass spectrometry and an incremental lifetime cancer risks (ILCRs) assessment model, the bioaccumulation and cancer risk of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) in leafy vegetables (Vernonia amygdalina and Lasianthera africanum) grown in soils within an automobile repair complex environment in Uyo, Nigeria was studied. The total PAHs concentrations recorded for soils ranged from 0.02 to 1.77mg/kg. The highest level of 1.77mg/kg was recorded for soils from the main automobile repair complex (site 1). Low molecular weight (LMW) PAHs were predominant although some high molecular weight (HMW) PAHs suites (0.04mg/kg of chrysene and 0.04 of benzo[k]fluoranthene) were also found in site 1. The leafy vegetables accumulated PAHs were mostly LMW. Accumulation levels were similar but the extent of PAH uptake in vegetables was species dependent as V. amygdalina accumulated more (0.81mg/kg). The bioaccumulation factors (BaFs) calculated ranged from 0.22 to 0.63 for L. africanum, and 0.18 to 0.55 for V. amygdalina in site 1 where high PAH levels were recorded in soil. Pearson correlation coefficient analysis revealed a strong positive relation between the PAH content of soil and the amount accumulated by L. africanum (r=0.5) and V. amygdalina (r=0.8) at p=0.05. The vegetable's potential to bioaccumulate PAHs is indicative of their use as good bioindicators for PAH contamination in soil. Only two of the USEPA possible human carcinogenic PAHs were detected, and carcinogenic risk assessment based on occupational exposures to soil particles by adults revealed that the total risk level (7.17×10-5) contribution from incidental soil ingestion, dermal contact, and soil particle dust inhalation slightly exceed the USEPA acceptable limits (< 1.00×10-5). There is a need for public education on consumption of vegetables grown in and around automobile repair complexes across Nigeria.

Occurence of the phthalate esters in soil and street dust samples from the Novi Sad city area, Serbia, and the influence on the children’s and adults’ exposure

This is the first study reporting the presence of 6 phthalic acid esters (PAEs) in 60 composite soil and street dust samples collected in the urban zone of Novi Sad, the second largest city in Serbia. The results were further used to assess children’s and adults’ PAEs nondietary daily intakes (DIs) through incidental soil and dust ingestion and/or dermal absorption. The study could be regarded as the important baseline for future monitoring of PAEs in the urban environments, particularly as it contributes to the rare data on PAEs occurence in the street dust.All 6 PAEs were detected in every analyzed soil and street dust samples from 0.0002mgkg−1 to 4.82mgkg−1, with the highest level obtained for di-(2-ethylhexyl) phthalate (DEHP), which was the most dominant PAE (70–96%). The highest total PAEs (Σ6PAEs) contents in soil (2.12mgkg−1) and street dust (5.45mgkg−1) samples were obtained for the samples from city parks. In all soil samples, Σ6PAEs exceeded the soil sustainable quality limit sets by the relevant Serbian Regulation, but were much lower than the limit requiring remediation measures. Concerning the estimated DIs, children were more susceptible to PAEs intake than adults regardless of the exposure routes. All the estimated DIs values were far below the known reference values.

Using in vitro bioaccessibility to refine estimates of human exposure to PAHs via incidental soil ingestion

PAH bioaccessibility in contaminated soil was determined using the organic physiologically based extraction test with the inclusion of a sorption sink. Silicone cord was incorporated into the assay in order to overcome the limited capacity of the in vitro medium to accommodate desorbable PAHs. Initially, silicone cord sorption efficacy was determined by assessing sorption kinetics using PAH-spiked sand (phenanthrene, pyrene and benzo[a]pyrene; 10–1000mgkg−1). Irrespective of PAH and concentration, >95% of the initial PAH mass partitioned into the silicone cord within 12h although rates were lower at higher concentration and with increasing hydrophobicity. When PAH bioaccessibility was assessed in contaminated soil (n=18), contamination source (i.e. pyrogenic versus petrogenic) influenced PAH bioaccessibility. Individual PAH bioaccessibility ranged up to 81.7±2.7% although mean values ranged from 2.1 (acenaphthalene) to 20.8% (benzo[k]fluoranthene) with upper 95% confidence intervals of the means of 4.5 and 28.3% respectively. Although a PAH in vivo–in vitro correlation is yet to be established, bioaccessibility approaches incorporating sorption sinks represent a robust approach for estimating PAH bioavailability as the desorbable fraction may be a conservative measure of the absorbable fraction.