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Supplemental_Information for Polycyclic aromatic hydrocarbons in processed yard trash by Ying Guo, Steven J Laux, Melissa Burdier, Peng Gao, Lena Q Ma and Timothy G Townsend in Waste Management & Research

Early-life arsenic (As) exposure is a particular health concern. However, it is unknown if As ingested early in life is more readily absorbed from the gastrointestinal (GI) tract, i.e., higher in oral bioavailability. Here, weanling (3-week) and adult (6-week-old) female mice were exposed to arsenate in the diet (10 mu g g-1) over a 3-week period with As oral bioavailability estimated using As urinary excretion as the bioavailability endpoint. The As urinary excretion factor was 1.54-fold higher in weanling mice compared to adult mice (82.2 +/- 7.29 versus 53.1 +/- 3.73%), while weanling mice also showed 2.28-, 1.50-, 1.48-, and 1.89-fold higher As concentration in small intestine tissue, blood, liver, and kidneys, demonstrating significantly higher As oral bioavailability of early-life exposure. Compared to adult mice, weanling mice significantly differed in gut microbiota, but the difference did not lead to remarkable differences in As biotransformation in the GI tract or tissue and in overall gut metabolite composition. Although the expression of several metabolites (e.g., atrolactic acid, hydroxyphenyllactic acid, and xanthine) was up-regulated in weanling mice, they had limited ability to elevate As solubility in the intestinal tract. Compared to adult mice, the intestinal barrier function and intestinal expression of phosphate transporters responsible for arsenate absorption were similar in weanling mice. However, the small intestine of weanling mice was characterized by more defined intestinal villi with greater length and smaller width, providing a greater surface area for As to be absorbed across the GI barrier. The results highlight that early-life As exposure can be more readily absorbed, advancing the understanding of its health risk. Refereed/Peer-reviewed

Refereed/Peer-reviewed Reducing lead (Pb) exposure via oral ingestion of contaminated soils is highly relevant for child health. Elevating dietary micronutrient iron (Fe) intake can reduce Pb oral bioavailability while being beneficial for child nutritional health. However, the practical performance of various Fe compounds was not assessed. Here, based on mouse bioassays, ten Fe compounds applied to diets (100–800 mg Fe kg−1) reduced Pb oral relative bioavailability (RBA) in two soils variedly depending on Fe forms. EDTA-FeNa was most efficient, which reduced Pb-RBA in a soil from 79.5 ± 14.7 % to 23.1 ± 2.72 % (71 % lower) at 100 mg Fe kg−1 in diet, more effective than other 9 compounds at equivalent or higher doses (3.6–68 % lower). When EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous bisglycinate were supplemented, Fe-Pb co-precipitation was not observed in the intestinal tract. EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous sulfate suppressed duodenal divalent metal transporter 1 (DMT1)mRNA relative expression similarly (27–68 % lower). In comparison, among ten compounds, EDTA-FeNa elevated Fe concentrations in mouse liver, kidney, and blood (1.50–2.69-fold higher) most efficiently, suggesting the most efficient Fe absorption that competed with Pb. In addition, EDTA was unique from other organic ligands, ingestion of which caused 12.0-fold higher Pb urinary excretion, decreasing Pb concentrations in mouse liver, kidney, and blood by 68–88 %. The two processes (Fe-Pb absorption competition and Pb urinary excretion with EDTA) interacted synergistically, leading to the lowest Pb absorption with EDTA-FeNa. The results provide evidence of a better inhibition of Pb absorption by EDTA-FeNa, highlighting that EDTA-FeNa may be the most appropriate supplement for intervention on human Pb exposure. Future researches are needed to assess the effectiveness of EDTA-FeNa for intervention on human Pb exposure.

Refereed/Peer-reviewed Microplastics exposure is a new human health crisis. Although progress in understanding health effects of microplastic exposure has been made, microplastic impacts on absorption of co-exposure toxic pollutants such as arsenic (As), i.e., oral bioavailability, remain unclear. Microplastic ingestion may interfere As biotransformation, gut microbiota, and/or gut metabolites, thereby affecting As oral bioavailability. Here, mice were exposed to arsenate (6 μg As g−1) alone and in combination with polyethylene particles of 30 and 200 μm (PE-30 and PE-200 having surface area of 2.17 × 103 and 3.23 × 102 cm2 g−1) in diet (2, 20, and 200 μg PE g−1) to determine the influence of microplastic co-ingestion on arsenic (As) oral bioavailability. By determining the percentage of cumulative As consumption recovered in urine of mice, As oral bioavailability increased significantly (P < 0.05) from 72.0 ± 5.41% to 89.7 ± 6.33% with PE-30 at 200 μg PE g−1 rather than with PE-200 at 2, 20, and 200 μg PE g−1 (58.5 ± 19.0%, 72.3 ± 6.28%, and 69.2 ± 17.8%). Both PE-30 and PE-200 exerted limited effects on pre- and post-absorption As biotransformation in intestinal content, intestine tissue, feces, and urine. They affected gut microbiota dose-dependently, with lower exposure concentrations having more pronounced effects. Consistent with the PE-30-specific As oral bioavailability increase, PE exposure significantly up-regulated gut metabolite expression, and PE-30 exerted greater effects than PE-200, suggesting that gut metabolite changes may contribute to As oral bioavailability increase. This was supported by 1.58–4.07-fold higher As solubility in the presence of up-regulated metabolites (e.g., amino acid derivatives, organic acids, and pyrimidines and purines) in the intestinal tract assessed by an in vitro assay. Our results suggested that microplastic exposure especially smaller particles may exacerbate the oral bioavailability of As, providing a new angle to understand health effects of microplastics.

Since its first publication in 1970, the Critical Reviews in Environmental Science and Technology (CREST) journal has served as an international forum for the publication of comprehensive, critical...

Refereed/Peer-reviewed Ingestion of metal-contaminated soils poses risks to human health. To accurately assess the risks, in vitro assays have been developed to measure metal bioaccessibility. However, they often differ considerably in gastrointestinal fluid components and assay parameters, leading to inconsistent bioaccessibility results. As such, in vitro assays need to be validated against in vivo bioassays based on in vivo-in vitro correlations (IVIVCs). To help researchers to select the best in vitro assay and increase the robustness of the IVIVCs, there is a need to review and compile existing data. In this review, we focus on three metals (As, Pb, and Cd), five common in vitro assays (SBRC, UBM, IVG, DIN, and PBET), and two in vivo bioassays (mouse and swine models). Specifically, we 1) discuss variations in metal bioaccessibility measurements among different in vitro assays, 2) identify the roles of major gastrointestinal fluid constitutes and assay parameters in affecting metal bioaccessibility, 3) summarize weaknesses associated with existing IVIVCs, and 4) establish new IVIVCs using pooled soil samples from different studies. In addition, future research directions are highlighted, including better understanding of the roles of gastrointestinal fluid components, improving in vitro assays to better correlate with in vivo bioassays, expanding bioaccessibility measurements using different in vitro assays, validation of IVIVCs using independent soils, assessing the reliability of in vitro assays in remediated soils, and addressing the mechanisms behind IVIVCs.

Mushrooms accumulate arsenic (As), yet As concentrations, speciation, and localization in cultivated mushrooms across a large geographic distribution are unknown. We characterized 141 samples of nine species from markets in nine capital cities in China, with samples of Lentinula edodes, Pleurotus ostreatus, and Agaricus bisporus being analyzed for As speciation and localization. Total As concentrations ranged from 0.01 to 8.31 mg kg-1 dw, with A. bisporus (0.27-2.79 mg kg-1) containing the most As followed by P. ostreatus and L. edodes (0.04-8.31 and 0.12-2.58 mg kg-1). However, As in A. bisporus was mostly organic including nontoxic arsenobetaine, while P. ostreatus and L. edodes contained mainly inorganic As (iAs). On the basis of in situ imaging using LA-ICP-MS, As in L. edodes was localized to the surface coat of the cap, while As in P. ostreatus was localized to the junction of the pileus and stipe. When As speciation and daily mushroom consumption (1.37 g d-1 dw) are considered, daily mushroom consumption may result in elevated iAs exposure, with increased bladder and lung cancer rates up to 387 cases per 100000. Our study showed that market mushrooms could be a health risk to the general public so its production should be monitored. Refereed/Peer-reviewed

Animal bioassays have been developed to estimate oral relative bioavailability (RBA) of metals in soil, dust, or food for accurate health risk assessment. However, the comparability in RBA estimates from different labs remains largely unclear. Using 12 soil and soil-like standard reference materials (SRMs), this study investigated variability in lead (Pb) and arsenic (As) RBA estimates employing a mouse bioassay in 3 labs at Nanjing University, University of Jinan, and Shandong Normal University. Two performances of the bioassay at Nanjing University in 2019 and 2020 showed reproducible Pb and As RBA estimates, but increasing the number of mouse replicates in 2020 produced more precise RBA measurements. Although there were inter-lab variations in diet consumption rate and metal accumulation in mouse liver and kidneys following SRM ingestion due to differences in diet composition, bioassays at 3 labs in 2019 yielded overall similar Pb and As RBA estimates for the 12 SRMs with strong linear correlations between each 2 of the 3 labs for Pb (R2 = 0.95–0.98 and slope = 0.85–1.02) and As RBA outcomes (R2 = 0.46–0.86 and slope = 0.56–0.79). The consistency in RBA estimates was attributed to the relative nature of the final bioavailability outcome, which might overcome the inter-lab variation in diet consumption and metal uptake in mice. These results increased the confidence of use of mouse bioassays in bioavailability studies. Refereed/Peer-reviewed

Oral bioavailability of arsenic (As) determines levels of As exposure via ingestion of As-contaminated soil, however, the role of gut microbiota in As bioavailability has not evaluated in vivo although some in vitro studies have investigated this. Here, we made a comparison in As relative bioavailability (RBA) estimates for a contaminated soil (3913 mg As kg−1) using a mouse model with and without penicillin perturbing gut microbiota and metabolites. Compared to soil exposure alone (2% w/w soil in diets), addition of penicillin (100 or 1000 mg kg−1) reduced probiotic Lactobacillus and sulfate-reducing bacteria Desulfovibrio, enriched penicillin-resistant Enterobacter and Bacteroides, and decreased amino acid concentrations in ileum. With perturbed gut microbiota and metabolic profile, penicillin and soil co-exposed mice accumulated 2.81–3.81-fold less As in kidneys, excreted 1.02–1.35-fold less As in urine, and showed lower As-RBA (25.7–29.0%) compared to mice receiving diets amended with soil alone (56 ± 9.63%). One mechanism accounted for this is the decreased concentrations of amino acids arising from the gut microbiota shift which resulted in elevated iron (Fe) and As co-precipitation, leading to reduced As solubilization in the intestine. Another mechanism was conversion of bioavailable inorganic As to less bioavailable monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV) by the antibiotic perturbed microflora. Based on in vivo mouse model, we demonstrated the important role of gut microbiota and gut metabolites in participating soil As solubilization and speciation transformation then affecting As oral bioavailability. Results are useful to better understand the role of gut bacteria in affecting As metabolism and the health risks of As-contaminated soils Refereed/Peer-reviewed

To test high cadmium (Cd) concentration may not be high in health risk when considering Cd bioavailability, we assessed variation of Cd relative bioavailability (RBA, relative to CdCl2) using a mouse assay for 14 vegetables of water spinach, amaranth, and pakchoi. Cadmium concentration varied from 0.13 ± 0.01–0.37 ± 0.00 μg g–1 fw. Cadmium-RBA also varied significantly from 22.9 ± 2.12–77.2 ± 4.46%, however, the variation was overall opposite to that of Cd concentration, as indicated by a strong negative correlation between Cd-RBA and Cd concentration (R2 = 0.43). Based on both Cd concentration and bioavailability, the identified high-Cd pakchoi variety resulted in significantly lower Cd intake than the high-Cd varieties of water spinach and amaranth (4.74 ± 0.05 vs. 10.1 ± 0.54 and 8.03 ± 0.04 μg kg–1 bw week–1) due to significantly lower Cd-RBA (22.9 ± 2.12 vs. 77.2 ± 4.46 and 51.3 ± 2.93%). The lower Cd-RBA in pakchoi was due to its significantly higher Ca and lower phytate concentrations, which facilitated the role of Ca in inhibiting intestinal Cd absorption. This was ascertained by observation of decreased Cd-RBA (90.5 ± 12.0% to 63.5 ± 5.53%) for a water spinach when elevating its Ca concentration by 30% with foliar Ca application. Our results suggest that to assess food Cd risk, both total Cd and Cd bioavailability should be considered. Refereed/Peer-reviewed

Soils are often co-contaminated with As, Pb, and Cd. To what extent ingested metal(loid)s interact with each other in the gastrointestinal tract and influence their RBA (relative bioavailability) is largely unknown. Three soils predominantly contaminated with As (MS, mining/smelting impacted), Pb (WR, wire rope production impacted), and Cd (EP, enamel pottery production impacted) were administered to mice individually or in binary and tertiary combinations with sodium arsenate, Cd chloride, and/or Pb acetate. In binary combinations, 10-fold higher Pb addition decreased As-RBA in MS (26.0 ± 6.28% to 17.1 ± 1.08%), while 10-fold higher As addition decreased Pb-RBA in WR (61.3 ± 2.41% to 28.8 ± 5.45%). This was possibly due to the formation of insoluble Pb arsenate in mouse intestinal tract, as indicated by the formation of precipitates when As and Pb co-occurred in water or simulated human gastrointestinal fluids. Due to competition for shared absorption transporters, 10- A nd 100-fold higher Pb addition decreased Cd-RBA in EP (95.8 ± 12.9% to 67.8 ± 12.8% and 62.8 ± 8.24%). Tertiary combinations showed that interactions between two metal(loid)s were affected by the presence of the third metal(loid). Our study suggests that As oxyanion could interact with Pb or Cd ions in the mouse gastrointestinal tract, and the interactions vary depending on concentration and solution characteristics Refereed/Peer-reviewed

Dietary Cd intake is often estimated without considering Cd bioavailability. Measured urinary Cd for a cohort of 119 nonsmokers with rice as a staple was compared to predicted values from rice-Cd intake with and without considering Cd relative bioavailability (RBA) in rice based on a steady state mouse kidney bioassay and toxicokinetic model. The geometric mean (GM) of urinary Cd and β 2 -microglobulin was 1.08 and 234 μg g -1 creatinine. Applying Cd-RBA in foods to aggregate Cd intake (41.5 ± 12.4, 48.0 ± 9.3, 48.8 ± 21.3% for rice, wheat, and vegetables), rice was the largest contributor (71%). For 63 participants providing paired urine and rice samples, the predicted GM of urinary Cd at 4.14 μg g -1 based on total Cd in rice was 3.5 times that of measured value at 1.20 μg g -1 , while incorporating Cd-RBA to assess rice-Cd intake made the two closer with GM at 1.07 μg g -1 . The cohort findings were extended to a national scale, with urinary Cd for nonsmokers from rice Cd intake was mapped at province/city levels after considering rice Cd-RBA. Therefore, incorporating Cd bioavailability to assess dietary Cd intake is a valuable tool to accurately estimate human Cd exposure and associated health risk. Refereed/Peer-reviewed

A steady-state mouse model was developed to determine arsenic (As) relative bioavailability (RBA) in rice to r efine As exposure in humans. Fifty-five rice samples from 15 provinces of China were analyzed for total As, with 11 cooked for As speciation and bioavailability assessment. Arsenic concentrations were 38-335 μg kg -1 , averaging 133 μg kg -1 , with As III being dominant (36-79%), followed by DMA V (18-58%) and As V (0.5-16%). Following oral doses of individual As species to mice at low As exposure (2.5-15 μg As per mouse) over a 7-d period, strong linear correlations (R 2 = 0.99) were observed between As urinary excretion and cumulative As intake, suggesting the suitability and sensitivity of the mouse bioassay to measure As-RBA in rice. Urinary excretion factor for DMA V (0.46) was less than inorganic As (0.63-0.69). As-RBA in cooked rice ranged from 13.2 ± 2.2% to 53.6 ± 11.1% (averaging 27.0 ± 12.2%) for DMA V and 26.2 ± 7.0% to 49.5 ± 4.7% (averaging 39.9 ± 8.3%) for inorganic As. Calculation of inorganic As intake based on total inorganic As in rice overestimated As exposure by 2.0-3.7 fold compared to that based on bioavailable inorganic As. For accurate assessment of the health risk associated with rice consumption, it is important to consider As bioavailability especially inorganic As in rice. Refereed/Peer-reviewed

Metal contamination in soil, dust, and food matrices impacts the health of millions of people worldwide. During the past decades, various animal bioassays have been developed to determine the relative bioavailability (RBA) of As, Pb, and Cd in contaminated soils, dust, and foods, which vary in operational approaches. This review discusses the strengths and weaknesses of different animal models (swine and mice), dosing schemes (single gavage dose, repeated gavage dose, daily repeated feeding, and free access to diet), and end points (blood, urine, and tissue) in metal-RBA measurement; compares metal-RBA obtained using mouse and swine bioassays, different dosing schemes, and different end points; and summarizes key findings on As-, Pb-, and Cd-RBA values in contaminated soils, dust, and foods. Future directions related to metal-RBA research are highlighted, including (1) comparison of metal-RBA determinations between different bioassays and different laboratories to ensure robust bioavailability data, (2) enhancing the metal-RBA database for contaminated dust and foods, (3) identification of physiological and physicochemical mechanisms responsible for variability in metal-RBA values, (4) formulation of strategies to decrease metal-RBA values in contaminated soils, dust, and foods, and (5) assessing the impacts of cocontaminants on metal-RBA measurement. Refereed/Peer-reviewed

Organoarsenicals have been used in poultry production for years, however, studies focused on roxarsone (ROX), with little attention to p-arsanilic acid (ASA). We assessed arsenic (As) concentration and speciation in chicken meat collected from 10 cities in China. The geometric mean for total As in 249 paired raw and cooked samples was 4.85 and 7.27 μg kg–1 fw, respectively. Among 81 paired raw and cooked samples, ASA and ROX were detected in >90% samples, suggesting the prevalence of organoarsenical use in China. ASA contributed the most (45% on average) to total As in cooked samples, followed by As(V), DMA, As(III), and ROX (7.2–22%). ASA was found to contribute more to total As in chicken meat compared to ROX for the first time. Arsenic in chicken meat showed considerable geographic variation, with higher inorganic arsenic (iAs) being detected from cities with higher ROX and ASA, indicating that organoarsenical use increased iAs concentration in chicken meat. When health risk was estimated, dietary exposure to iAs would result in an increase of 3.2 bladder and lung cancer cases per 100,000 adults. The result supports the removal of organoarsenicals in poultry production from Chinese market and further supports its removal from the global markets. Refereed/Peer-reviewed

Recent studies have investigated lead (Pb) concentrations in lip products but little is known about its oral bioavailability. In this study, 75 lipsticks and 18 lip glosses were assessed for Pb concentration, while 15 samples were assessed for Pb relative bioavailability (RBA, relative to Pb acetate absorption) using a mouse femur assay. Lead concentrations were 0.2-10 185 mg kg(-1), with 21 samples exceeding the Chinese limit of 40 mg kg(-1). Samples with orange and pink colors and/or low cost contained higher Pb concentrations. For samples with Pb > 7500 mg kg(-1), Pb was present due to the addition of lead chromate (PbCrO4) as a colorant, which was confirmed by X-ray absorption near-edge structure analysis. Lead RBA in 15 samples (87-10 185 mg kg(-1)) ranged from 23% to 95%, being significantly higher in moderate Pb (56-95%; 87-300 mg kg(-1)) than high Pb samples (23-48%; >300 mg kg(-1)). The calculation of Pb intake based on Pb-RBA showed that lip product ingestion contributed 5.4-68% of the aggregate Pb exposure for women depending on Pb concentration. The high Pb concentration in some lip products together with their moderate Pb-RBA suggests that lip product ingestion is a potential health concern to women. Refereed/Peer-reviewed

Different animals and biomarkers have been used to measure the relative bioavailability of arsenic (As-RBA) in contaminated soils. However, there is a lack of As-RBA comparison based on different animals (i.e., swine and mouse) and biomarkers [area under blood As concentration curve (AUC) after a single gavaged dose vs steady-state As urinary excretion (SSUE) and As accumulation in liver or kidney after multiple doses via diet]. In this study, As-RBA in 12 As-contaminated soils with known As-RBA via swine blood AUC model were measured by mouse blood AUC, SSUE, and liver and kidney analyses. As-RBA ranges for the four mouse assays were 2.8-61%, 3.6-64%, 3.9-74%, and 3.4-61%. Compared to swine blood AUC assay (7.0-81%), though well correlated (R2 = 0.83), the mouse blood AUC assay yielded lower values (2.8-61%). Similarly, strong correlations of As-RBA were observed between mouse blood AUC and mouse SSUE (R2 = 0.86) and between urine, liver, and kidney (R2 = 0.75-0.89), suggesting As-RBA was congruent among different animals and end points. Different animals and biomarkers had little impact on the outcome of in vivo assays to validate in vitro assays. On the basis of its simplicity, mouse liver or kidney assay following repeated doses of soil-amended diet is recommended for future As-RBA studies. Refereed/Peer-reviewed

Faced with severe soil pollution, China has promulgated environmental laws, regulations, and standards to control soil pollution. For example, in 2016 the State Council of China issued a Soil Pollution Prevention and Control Action Plan.The plan was aimed at making 90% of polluted farmland soil safe for human use by 2020 and 95% by 2030, as specified in China’s 13th Five-Year Plan. The Chinese government has made progress by promulgating policies, but the country still lags in its effort to realize these goals in actual practice. China has undertaken 100 soil remediation projects from 2013 to 2015, and the number of projects is 28, 40, and 32, respectively,indicating a decline in 2015 compared to 2014. Farmland restoration accounts for only about 10% of the projects,significantly below the expectations of the government. A significant problem facing local governments, companies and the general public is the lack of clarity on the extent of China’s soil pollution. In 2014, a soil survey report was released by the government. It indicated that 16% of the samples collected from sites across 1500 surveyed areas representing 6.3 million square kilometers exceeded soil standards for a range of organic and inorganic contaminants. However, the survey was limited in its extent and did not fully reflect the actual extent of soil pollution across the Chinese landscape. We believe that more comprehensive information is needed to assess the risk to the population and to prioritize remediation of agricultural and urban soils. Refereed/Peer-reviewed

To determine the effects of dietary constituents on soil Pb oral bioavailability, Pb relative bioavailability (RBA) in 3 soils contaminated by zinc smelting (ZS), wire-rope production (WR), and metal mining (MM) was measured under fasted and fed states with 9 foods. Under fasted state, Pb-RBA was 84.4 ± 10.3, 82.6 ± 4.70, and 32.3 ± 1.10% for ZS, WR, and MM soils; however, it decreased by 1.3-3.5 fold to 23.9-58.8, 25.6-49.9, and 14.8-24.2% under fed states with foods excluding Pb-RBA with egg in WR soil (97.3 ± 4.46%), and with cabbage and egg in MM soil (40.0 ± 8.62 and 44.4 ± 0.96%). In the presence of foods, egg and pork with significantly higher protein and fat contents leaded to the highest soil Pb-RBA (44.4-97.3%), while Pb-RBA determined with mineral-rich mouse feed was 1.6-7.9 fold lower (9.41-13.5%), suggesting high fat and protein foods tended to increase soil Pb-RBA, while high mineral diets decreased soil Pb-RBA. The increased Pb-RBA of MM soil with cabbage compared to fasted state was due to high organic content in cabbage, which could increase soil Pb solubility by inhibiting Fe and Pb co-precipitation in the intestine. For accurate assessment of health risks of contaminated soils, dietary influence on soil Pb-RBA should be considered. Refereed/Peer-reviewed

Incidental ingestion of household dust is an important arsenic (As) exposure pathway for children. However, compared to soils, assessment of As relative bioavailability (RBA) in household dust is limited. In this study, As-RBA in 12 household dust samples (7–38 mg kg(–1)) was measured using an in vivo mouse model and compared to As bioaccessibility determined using 4 assays [Solubility Bioaccessibility Research Consortium method (SBRC), in vitro gastrointestinal method (IVG), Deutsches Institut für Normunge.V. method (DIN), and physiologically based extraction test (PBET)]. Arsenic RBA ranged from 21.8 ± 1.6 to 85.6 ± 7.2% with samples containing low Fe and high total organic carbon content having higher As-RBA. Strong in vivo–in vitro correlations (IVIVC) were found between As-RBA and As bioaccessibility for SBRC and DIN (r2 = 0.63–0.85), but weaker ones were obtained for IVG and PBET (r2 = 0.29–0.55). The developed IVIVC for SBRC and DIN were used to calculate As-RBA based on As bioaccessibility for an additional 12 household dust samples. Although As bioaccessibility differed significantly (up to 7.7-fold) based on in vitro methods, predicted As-RBA was less variable (up to 3.0-fold) when calculated using As bioaccessibility data and the corresponding IVIVC. Our data suggested that both SBRC and DIN had potential to assess As bioavailability in household dust samples; however, additional research is needed. Refereed/Peer-reviewed

To determine the effectiveness of mineral dietary supplements to modulate cadmium (Cd) exposure, an in vivo mouse bioassay was conducted to determine Cd relative bioavailability (Cd-RBA) in Cd-contaminated rice (0.80 mg Cd kg(-1)) with and without Zn, Fe, or Ca supplements as nitrate or chloride salts. Without mineral supplements, Cd-RBA was 43 +/- 5.3% based on average Cd accumulation in the liver plus kidneys as the end point. Among Ca(NO3)(2), Zn(NO3)(2), and Fe(NO3)(2) supplements, 150-5000 mg kg(-1) Ca was the most effective in reducing rice Cd-RBA by 31-80% to 8.5-29%, while 30-200 mg kg(-1) Zn supplements was ineffective, with Cd-RBA being 33-57%. Low Fe at

Due to their static nature, physiologically based in vitro assays often fail to provide sufficient sorption capacity for hydrophobic organic contaminants (HOCs). The addition of a sorption sink to in vitro intestinal solution has the potential to mimic dynamic intestinal uptake for HOCs, thereby increasing their desorption from soil. However, the effectiveness of sorption sinks for improving in vitro assays needs to be compared with in vivo data. In this study, Tenax was added as a sorption sink into the physiologically based extraction test (PBET), while DDT and its metabolites (DDTr) were investigated as typical HOCs. Tenax added at 0.01-0.2 g to the PBET intestinal solution sorbed ∼100% of DDTr in 6.3-19 min, indicating its ability as an effective sorption sink. DDTr bioaccessibility in six contaminated soils using Tenax-improved PBET (TI-PBET; 27-56%) was 3.4-22 fold greater than results using the PBET (1.2-15%). In vivo DDTr relative bioavailability (RBA) was measured using a mouse adipose model with values of 17.9-65.4%. The inclusion of Tenax into PBET improved the in vivo-in vitro correlation from r2 = 0.36 (slope = 2.1 for PBET) to r2 = 0.62 (slope = 1.2 for TI-PBET), illustrating that the inclusion of Tenax as a sorption sink improved the in vitro prediction of DDTr RBA in contaminated soils. Refereed/Peer-reviewed

Few studies have assessed As bioaccessibility in housedust using different in vitro assays and compared to those in contaminated soils. We determined As bioaccessibility in 24 housedust samples (4.48-38.2mgkg-1) using SBRC, IVG, DIN, and PBET assays and they averaged 73, 68, 53, and 48% in the gastric phase and 26, 46, 55 and 43% in the intestinal phase of the 4 assays. The corresponding As bioaccessibility in 34 As-contaminated soils (22-6899mgkg-1) were 34, 25, 22, and 22% in the gastric phase and 18, 19, 21, and 20% in the intestinal phase, which was 1.5-2.7 fold lower than those in housedust possibly due to differences in contamination sources and properties. Based on the gastric phase of SBRC assay, As bioaccessibility was 44-96% in housedust and 2.3-80% in soils. Variation in As bioaccessibility among assays was similar for housedust and soils, with SBRC assay providing the highest bioaccessibility in gastric phase. In intestinal phase, dissolved As was probably adsorbed onto precipitated iron oxides, causing a sharp decrease in As bioaccessibility by SBRC assay. Unlike SBRC assay, gastric constituents (pepsin, mucin, phosphate, and citrate) in other 3 assays inhibited As adsorption and/or enhanced As dissolution, leading to greater As bioaccessibility. The greater As bioaccessibility in housedust than soil suggests the potential of greater health risk from As exposure to housedust than soil. Refereed/Peer-reviewed

Food is a major source of human exposure to perfluorooctanoic acid (PFOA), however, PFOA bioavailability in food has not been studied. An in vivo mouse model and three in vitro methods (unified BARGE method, UBM; physiologically based extraction test, PBET; and in vitro digestion method, IVD) were used to determine the relative bioavailability and bioaccessibility of PFOA in the presence of 17 foods. PFOA was mixed with foods of different nutritional compositions and fed to mice over a 7-d period. PFOA relative bioavailability was determined by comparing PFOA accumulation in the liver following PFOA exposure via food to that in water. PFOA bioavailability relative to water ranged from 4.30 ± 0.80 to 69.0 ± 11.9% and was negatively correlated with lipid content (r = 0.76). This was possibly due to competitive sorption of free fatty acids with PFOA onto transporters on intestine epithelial cells. Besides, cations in the gastrointestinal tract, such as Ca2+ and Mg2+, are capable of complexing PFOA and partitioning to the lipid phase. On the other hand, when assessed using in vitro assays, PFOA bioaccessibility varied with methods, being 8.7–73% (UBM), 9.8–99% (PBET), and 21–114% (IVD). PFOA bioaccessibility was negatively correlated with lipid content when assessed using UBM (r = 0.82); however, a poor correlation with food composition was observed for PBET and IVD (r = 0.01–0.50). When in vivo and in vitro data were compared, a strong correlation was observed for UBM (r = 0.79), but poor relationships were observed for PBET and IVD (r = 0.11–0.22). This was probably because the higher lipolysis ability and presence of Ca2+ and Mg2+ in the gastrointestinal fluid of UBM resulted in a lower potential to form stable micelles compared to PBET and IVD. These results indicated that PFOA relative bioavailability was mainly affected by lipid content in foods, and UBM has the potential to determine PFOA bioaccessibility in food samples. Refereed/Peer-reviewed

House dust samples containing 25−738 mg of Pb kg−1 from 15 cities in China were assessed for in vitro Pb bioaccessibility and in vivo Pb relative bioavailability. On the basis of stable Pb isotope ratios, the Pb in dust samples mainly originated from coal combustion. Lead bioaccessibility was determined using gastric (GP) and intestinal phase (IP) of solubility bioaccessibility research consortium (SBRC), in vitro gastrointestinal (IVG), Deutsches Institut für Normunge.V.(DIN), and physiologically based extraction test methods(PBET), while Pb relative bioavailability (RBA) was determined using a mouse blood model. Lead bioaccessibility in 24 house dust samples varied significantly (23−99%)depending on the methods. Values from the IP were considerably lower than those from the GP because of the co-precipitation of Pb with iron and re-adsorption onto the dust matrix. The SBRC assay with lower GP pH produced higher Pb bioaccessibility because of enhanced Pb dissolution. When compared to mouse blood data using 12 dust samples (29−60%), SBRC−GP andDIN−GP data were correlated with Pb RBA with r2 values of 0.68 and 0.85 and intercepts 3.15 and 17.4, respectively. Overall,SBRC−GP had potential to predict Pb RBA in dust samples. However, our data suggested that more research is needed to develop a valid in vitro method for predicting Pb RBA in house dust. Refereed/Peer-reviewed