Arsenic concentrations and speciation in Australian and imported rice and commercial rice products

Abstract

Environmental contextIn countries where inhabitants are not exposed to arsenic-contaminated drinking water, food is the major source of potentially toxic inorganic arsenic. To complement the existing worldwide dataset on arsenic in rice, data are presented on Australian- and overseas-grown rice, and assessed in terms of possible risk. Only a diet comprising multiple serves of some rice products per day poses a potential risk to young children. AbstractArsenic concentrations and speciation measurements were determined for six varieties of Australian-grown rice (n = 130), imported rice (n = 53) and rice products (n = 56) from supermarkets. Total As, inorganic As and dimethylarsinic acid (DMA) concentrations in Australian rice ranged from 16 to 630 µg As kg−1 (mean ± s.d.: 220 ± 122 µg kg−1), 16 to 250 µg As kg−1 (92 ± 52 µg As kg−1) and <5 to 432 µg As kg−1 (125 ± 109 µg As kg−1), respectively. Total As, inorganic As and DMA concentrations in imported rice ranged between 31 and 376 µg As kg−1 (130 ± 98 µg kg−1), 17 and 198 µg As kg−1 (73 ± 40 µg As kg−1) and <5 and 327 µg As kg−1 (84 ± 92 µg As kg−1) respectively. Few samples exceeded the guidelines for inorganic As in polished rice. In rice products, total As, inorganic As and DMA concentrations ranged between 21 and 480 µg As kg−1 (160 ± 110 µg As kg−1), 20 and 255 µg As kg−1 (92 ± 78 µg As kg−1) and <5 and 340 µg As kg−1 (65 ± 69 µg As kg−1) respectively. Sixteen samples exceeded the 100 µg kg−1 maximum for inorganic As concentration in rice foods for infants and young children. Ingestion of multiple serves of some rice products poses a potential risk. Environmental chemistry gaps, on processes influencing As occurrence in rice, are discussed.

Widespread Occurrence of the Highly Toxic Dimethylated Monothioarsenate (DMMTA) in Rice Globally

“…Among the 140 rice samples, total As concentrations varied from 25.1 to 370 μg/kg (mean 143 μg/kg, median 132 μg/kg); iAs ranged from 18.3 to 220 μg/kg (mean 97.6 μg/kg, median 90.0 μg/kg); DMA ranged from 4.39 to 94.1 μg/kg (mean 29.4 μg/kg, median 28.0 μg/kg); and DMMTA ranged from <0.20 (i.e., limit of detection, being for 2 out of 140 samples) to 30.4 μg/kg (mean 10.4 μg/kg, median 10.0 μg/kg) (Figure A and Table S2). The ranges and means of total As and iAs obtained in the present study are similar to those reported previously for global studies of As in rice. ,,,,− Among the 140 rice samples, 12 samples (5%) exceeded the EU and Chinese limits for iAs in rice of 200 μg/kg. The proportion of As present as iAs varied from 41 to 98% (mean 68%), as DMA from 1.3 to 48% (mean 24%), and as DMMTA from 1.4 to 16% (mean 8%) (Figure B).…”

Arsenic Concentrations and Dietary Exposure in Rice-Based Infant Food in Australia

“…This is consistent with previous Australian results for rice-based foods [23]. The high tAs mean concentration in Australia probably resulted from the higher As concentrations in Australian rice than imported rice [13,24,40] and the higher Australian maximum level for tAs in rice compared to many countries (Table 1).…”

Effects of arsenite and dimethylarsenic on the growth and health of hydroponically grown commercial Doongara rice

“…soils and rocks (Palmer et al 2021) and the historical use of herbicides such as cacodylic acid (Limmer and Seyfferth 2020). There is a concern about human exposure to As, particularly for infants, through the consumption of rice and processed rice products (Sohn 2014;Maher et al 2018).…”