In Vitro Test-based Study on Health Risks of Arsenic in Typical Soils of China and Their Influencing Factors
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X53;X820.4

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Supported by the National Natural Science Foundation of China (No. 41807116), the Natural Science Foundation of Fujian Province of China (No. 2019J05035) and the Middle-aged and Young Teachers’ Educational Research Project of Fujian Province of China (No. JT180022)

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    Abstract:

    [Objective] This study aimed at accurate assessment of health risks of arsenic (As) in typical soils of China and comprehensive investigation of their influencing factors, based on oral bioaccessibility/bioavailability of soil As.[Method] Samples of five typical soils of the country, i.e. red soil, black soil, cinnamon soil, brown soil and yellow soil, were collected and prepared into As-contaminated samples by spiking As at 600 mg·kg-1. After one-month aging, bioaccessibility/bioavailability of soil As in the gastrointestinal tract of a human being were studied, and its health risk was evaluated by means of in vitro test (PBET-UF model). Besides, from the perspective of soil properties (soil basic physicochemical properties and As fractions), influencing factors of As bioaccessibility/bioavailability were explored and variation of As bioaccessibility/bioavailability with the soil analyzed.[Result] Results show that As bioaccessibility/bioavailability significantly varied between soils, as As bioaccessibility ranged from 37.2% to 71.8% in the gastric phase and from 49.0% to 73.3% in the small intestinal phase, while As bioavailability in the small intestinal phase ranged from 48.6% to 72.1%. It was indicated that from the stomach to the small intestine soil As was gradually dissolved by digestive fluids, and almost all the dissolved As in the small intestine could pass through the specific ultrafiltration membrane used to simulate small intestinal epithelium. Also, health risks of soil As through oral ingestion significantly varied with the soil. Based on the estimated As bioaccessibility in the gastric phase, carcinogenic and non-carcinogenic risks of As in the five soils varied in the range of 4.28×10-4~8.26×10-4and in the range of 14.86~28.69, respectively; and based on the estimated As bioavailability in the small intestinal phase, they did in the range of 5.59×10-4~8.30×10-4and in the range of 19.40~28.81, respectively. The carcinogenic risk and non-carcinogenic risk was two orders and one order of magnitude respectively higher than their respective acceptable limit. In addition, correlation analysis shows that between bioaccessibility/bioavailability of soil As was significantly related to certain soil properties.[Conclusion] Oral bioaccessibility/bioavailability of soil As is significantly and positively related to soil pH, migration coefficientS and migration coefficientW, but negatively to content of free Fe and Al oxides. Migration coefficientS is the main influencing factor determining bioaccessibility of soil As in the gastric phase, whereas soil pH is in the small intestinal phase. Although free Fe and Al oxides in the soils are not the determining factors directly affecting bioaccessibility/bioavailability of soil As in the gastric phase, they form new minerals with As, thus reducing the activity and consequent bioaccessibility/bioavailability of soil As. It is expected that all the findings in this study may contribute positively to making future field investigations of soil environmental quality of China more in line with the reality, and consummation of the methodologies for health risk assessment of heavy metal (loid) -contaminated soil.

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CHEN Xiaochen, HUANG Zhenjia, CHEN Yuqing, YAO Congcong, ZHANG Jianyu, DIAO Guowang, YUAN Ching, XU Kaiqin, LIU Xianhua.In Vitro Test-based Study on Health Risks of Arsenic in Typical Soils of China and Their Influencing Factors[J]. Acta Pedologica Sinica,2022,59(1):172-182.

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History
  • Received:May 14,2020
  • Revised:September 03,2020
  • Adopted:October 14,2020
  • Online: December 10,2020
  • Published: January 11,2022