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A steady-state mouse model was developed to determine arsenic (As) relative bioavailability (RBA) in rice to refine 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 AsIII being dominant (36--79%), followed by DMAV (18--58%) and AsV (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 (R² = 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 DMAV (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 DMAV 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. [ABSTRACT FROM AUTHOR]

Using in vitro bioaccessibility assays to predict Pb relative bioavailability (RBA) in contaminated soils has been demonstrated, however, limited research was performed on urban soils having lower Pb levels. In this study, 162 soils from urban parks in 27 capital cities in China were measured for Pb bioaccessibility using the SBRC assay, with Pb-RBA in 38 subsamples being measured using a mouse-kidney assay. Total Pb concentrations in soils were 9.3-1198 mg kg-1, with 92% of the soils having Pb concentrations <100 mg kg-1. Lead bioaccessibility in soils was 20-94%, increasing with Pb concentration up to 100 mg kg-1 (r = 0.44), however, limited variability in Pb bioaccessibility (60-80%) was observed for soils with Pb > 100 mg kg-1. On the basis of a stable isotope fingerprinting technique, coal combustion ash was identified as the major Pb source, contributing to the increased Pb bioaccessibility with increasing soil Pb concentration. Lead-RBA in soils was 17-87%, showing a strong linear correlation with Pb bioaccessibility (r2 = 0.61), with cross validation of the correlation based on random subsampling and leave-one-out approaches yielding low prediction errors. On the basis of the large sample size of 38 soils, this study demonstrated that the Pb-RBA predictive capability of the SBRC assay can be extended from mining/smelting impacted soils to urban soils with lower Pb levels. [ABSTRACT FROM AUTHOR]

Fingerprinting based on stable isotopes of lead (Pb) in blood and environmental media helps to identify Pb exposure pathways in children. However, previous studies used stable isotopes of total Pb in media. In this study, a wire rope production town in China (Zhuhang) was selected for investigating the effectiveness of using isotope ratios in bioaccessible Pb to identify childhood Pb exposure pathways. Blood Pb levels of 115 children in Zhuhang were 1.7-20.4 μg dL-1, averaging 6.1 ± 3.2 μg dL-1 (mean ± standard deviation), and were ~1.6 times the national average in China (3.9 ± 1.8 μg dL-1). Among different environmental media (housedust, soil, PM10, vegetables, rice, and drinking water), housedust (695 ± 495 mg kg-1) and vegetables [0.36 ± 0.40 mg (kg of fresh weight)-1] contained elevated Pb concentrations. The isotope ratios (207Pb/206Pb and 208Pb/206Pb) of total Pb were the highest in housedust (0.8587 ± 0.0039 and 2.1049 ± 0.0087) but lower than blood Pb ratios (0.8634 ± 0.0027 and 2.1244 ± 0.0061). When using bioaccessible Pb in housedust (0.8639 ± 0.0018 and 2.1171 ± 0.0036), the isotope ratios overlapped with blood Pb ratios, suggesting that incidental ingestion of housedust was the predominant contributor to children's blood Pb. Coupling the stable isotope technique with bioaccessible Pb is more reliable for identifying Pb exposure pathways than total Pb determinations. [ABSTRACT FROM AUTHOR]

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 fur 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 IVTVC. Our data suggested that both SBRC and DIN had potential to assess As bioavailability in household dust samples; however, additional research is needed. [ABSTRACT FROM AUTHOR]

House dust samples containing 25-738 mg of Pb kg-1 from 15 cities in China were assessed for in vitro Pb bio-accessibility 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 bio-accessibility 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 readsorption 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 and DIN-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. [ABSTRACT FROM AUTHOR]