(Reporter Shen Shusha) Recently, a test by the Karolinska Institute in Sweden found that some famous brands of baby rice may contain arsenic. Where does arsenic in rice flour come from? Numerous studies have shown that the enrichment of arsenic in rice paddies in Asia and other parts of the world can lead to the accumulation of arsenic in rice. At the 173st Oriental Science and Technology Forum held recently, Zhu Yongguan, a researcher at the Institute of Urban Environment of the Chinese Academy of Sciences, brought us new ideas for dealing with arsenic accumulation in rice.

Most people's impression of arsenic is that Pan Jinlian's arsenic poisoning and death. In fact, arsenic is widely present in nature as "inorganic arsenic" and "organic arsenic." The toxicity of organic arsenic is negligible, and inorganic arsenic is a toxic carcinogen.

The content of arsenic in rice grains is usually about 10 times that of large wheat. This is due to the fact that, under flooding conditions, arsenic released from the iron oxides in the soil is released into the solution and is easily absorbed by rice. In 2008, "Science" magazine in the United States used "arsenic and rice: an overlooked cancer risk" as its theme to report on the problem of arsenic accumulation in traditional rice planting seeds and proposed an effective solution to achieve dry rice seedlings. Significantly reduce the migration of arsenic into rice in the soil. However, dry rice cannot completely replace rice. The exploration of how to reduce arsenic in rice has not stopped. Zhu Yongguan’s team observed the key process of arsenic transport in rice through “Shanghai Light Sources”. They found that arsenic in rice is mainly in the form of trivalent arsenic, and it is known as trivalent arsenic methyltransferase. Substances can make trivalent arsenic “grow out” three methyl groups and become trimethyl arsenic that can be volatilized. Eventually “ride” the root transport “train” all the way up, and the leaves are volatilized into the air.

However, rice cannot produce trivalent arsenic methyltransferase on its own. Therefore, Zhu Yongguan’s team tried to “express” the trivalent arsenic methyltransferase gene that is present in the microorganisms into rice, thereby achieving the purpose of arsenic removal from rice. This technology provides new ideas for effective control of arsenic accumulation in rice.

The study also found that arsenic can interfere with the accumulation of other beneficial trace elements in rice grains. Therefore, the hazard of arsenic pollution is not only the toxicity of arsenic itself, but also includes the “malnutrition” caused by it. Zhu Yongguan said that fortunately, arsenic is mainly distributed in the epidermis, that is, in the rice paddy, and the process can effectively remove arsenic.