Bioaccessibility of Inorganic Arsenic in Rice: Probabilistic Estimation and Identification of Influencing Factors

Bioaccessibility, defined as the fraction of inorganic arsenic (iAs) that becomes soluble in the GI tract and ready for absorption, is one of the determining factors that impacts the iAs exposure through rice consumption. The objective of this study is to, based on published data, quantitatively characterize the bioaccessibility of iAs in rice and identify its influencing factors. A total of 256 published papers were identified and reviewed, among which eight were selected as they provide adequate data to support the analyses of bioaccessibility and influencing factors. A meta-analysis was performed to characterize the probabilistic distribution of the bioaccessibility of iAs. A general regression analysis was performed to identify the influencing factors of the bioaccessibility. A beta distribution (a = 4.91, b = 1.85) with a mean and 90th percentile interval of 73% (43%, 95%) was estimated to adequately describe the iAs bioaccessibility in rice. The regression analysis shows that grain size (p-value < 0.001) and the inorganic-to-total proportion of arsenic (p-value < 0.001) are negatively associated with bioaccessibility, while milling status has no impact.