Abstract
Studies have shown that rice (Oryza sativa L.) is one of the main sources of inorganic arsenic in foods. Rice absorbs arsenic from the soil and more so when planted in soils contaminated with agrochemicals residues. In this research, the concentration of arsenic in over 40 rice samples, selected randomly from paddy fields in the North of Thailand, was determined by inductively coupled plasma–mass spectrometry (ICP-MS). It was found that the average levels of arsenic in rice grown in uncontaminated soil was 1.8 x10-3 mg kg-1 (1.8 ppb) relatively lower than the guideline of 0.2 mg kg-1 (200 ppb) agreed by Codex Alimentarius for arsenic in rice. Thus, it is possible to suggest that a normal intake of Thai rice from the paddy fields of North Thailand, would not pose any significant adverse health effect on the consumer and import restriction of such produce on the ground of safety will be unreasonable.
Highlights
Arsenic is a toxic heavy metal that is widely distributed in the Earth’s crust and found naturally in the environment
The concentrations of arsenic in the 43 unpolished rice samples are shown (Figure1) and as far as can be ascertained, the rice samples were grown in uncontaminated soil where there was no history of industrial pollution
The present study showed that arsenic contents and the range in the samples are much lower when comparing with the Chinese limits which are permitted at 0.2 mg kg-1 for arsenic in rice grains [27]
Summary
Arsenic is a toxic heavy metal that is widely distributed in the Earth’s crust and found naturally in the environment. It is possible to be exposed to arsenic through air, soil, water and food. Approximately over 90% of rice worldwide is grown in Asia, including Thailand, and it is estimated that annual rice production will increase from 524 million tonnes to 700 million tonnes by 2025 [2]. The sale of rice for export has increased gradually from 4.0 million tonnes in 1990 to 10.6 million tonnes in 2011 [3]. By the end of 2016, Thailand exported around 8,712,050 million tonnes of rice worldwide [4]. In 2017, Thailand is expected to increase rice exports to 9.7 million tons [5].The quality of rice can directly impact on human health
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