Distribution and contents of gallium (Ga), arsenic (As) and the trace elements (Sr, Cs, Co and V) in rice grains and the risk assessment of As - 農業知識入口網

Abstract

Rice is the world’s second largest crop as well as a staple food for half of the global population. Recently, the trend of eating whole grains has raised due to
the health benefits. The bran, which is part of the brown rice and colored rice, is rich in phytochemicals, vitamin B complex, dietary fiber and trace elements.
In Taiwan, the high-tech industry and agriculture are both well- developed. Because of the planting environment, the toxic elements might uptake from the
rice plant roots during growing stages, then accumulate them in the harvested rice grains. Inorganic arsenic (As) is proved carcinogenic and is a Group 1
carcinogen. Gallium (Ga), is one of the metals that is used in the semiconductor industry in Taiwan, and its related research to environment  and human
health are still few. The objective of this study is to determine the distribution and accumulation of Ga, As and other trace elements in the rice grains. Firstly,
29 paddy rice samples from selected origins, including 15 japonica, 3 indica and 11 colored rice were fractionated into paddy, husk, brown rice, bran and
polished rice. Moisture and ash contents were determined and inductive coupled plasma-mass spectrometry (ICP-MS) was used to determine the contents
of Ga and As. Secondly, 69 commercial rice samples were purchased from local markets and the  contents of elements of Ga, As, strontium (Sr), cesium (Cs),
cobalt (Co) and vanadium (V) were determined. The results showed that the average moisture contents (11.02-13.67%) of rice grains  were similar among
each fraction. The trend of ash contents was husk (14.35%) > bran (9.12%) > paddy rice (4.76%) > brown rice (1.49%) > polished rice (0.70%). The trend of
Ga contents was  husk (1.431 mg/kg) > bran (1.079 mg/kg) > brown rice (0.144 mg/kg) > polished rice (0.074 mg/kg) while the bran (1.00 mg/kg) had the
highest content of As. In the 69 commercial rice  samples, As was detected in all of the samples and the contents in brown rice were significantly higher than
polished rice. Co and Cs were detected in one-third samples. The range of contents of As, Co and Cs  were 0.048-0.773,