Where does "arsenic" in Chen Xiuling and Li Junzhang / rice come from? Is Taiwan rice safe?

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Professor Chen Xiuling, Institute of Food Safety, Hygiene and risk Management, Chenggong University, Li Junzhang, Institute of Industrial Hygiene and Environmental Medicine, Chenggong University

With the development of industrialization, environmental sources discharge pollutants into the air, water and soil, threatening agriculture and food safety. Will these pollutants affect the production quality and price of the local agricultural and livestock industry? Will the crops planted be contaminated by heavy metals and accumulate in the bodies of eaters, thus affecting their health? For people in Taiwan, who eat rice as their main diet, these have always been issues of concern.

This article is reproduced from the ILSI Taiwan column, written by Professor Chen Xiuling of the Institute of Food Safety, Hygiene and risk Management of Chenggong University and Li Junzhang, a special professor of the Institute of Industrial Health and Environmental Medicine of Chenggong University, to introduce you to the chronic toxic substance "arsenic". Citing the data of arsenic content in rice at home and abroad, this paper points out the distribution characteristics of arsenic in rice grains, and finally discusses the safety of Chinese rice consumption. And how to reduce the risk of dietary arsenic exposure.

What is "arsenic"?

Arsenic is a kind of chronic toxic substance. When it is excessive in groundwater, it not only makes the groundwater undrinkable, but also has an adverse impact on the environment and ecology. Arsenic can be accumulated in the body by inhalation, ingestion and absorption through the skin. Excessive arsenic compounds will do harm to organisms if they cannot be excreted by metabolism and accumulate in the organism. The International Agency for Research on Cancer (International Agency for Research on Cancer,IARC) listed arsenic and inorganic arsenic as human carcinogens (Group 1) in 1987. it was confirmed that arsenic exposure is closely related to bladder cancer, skin cancer and kidney cancer.

The types of arsenic can be divided into two categories: organic arsenic and inorganic arsenic. organic arsenic is usually found in seafood food and has low toxicity to human body. after ingesting the body for about 1 to 2 days, it will be excreted through kidney metabolism. The most common forms are "dimethyl arsenic acid (DMA)" and "monomethyl arsenic acid (MMA)". Inorganic arsenic can be divided into three forms: heavy metal arsenic (As), trivalent arsenic (As2O3), and pentavalent arsenic (NaAsO3). The valence of arsenic can change with each other in organisms, of which trivalent arsenic (As2O3) is the most common and most toxic. Long-term excessive intake of inorganic arsenic will accumulate in the liver, kidney and gallbladder and other organs of the human body, causing chronic arsenism (figure 1).

Schematic diagram of the average concentration of arsenic species in rice grains (photo source ILSI Taiwan column November 2017)

The arsenic intake of Chinese people eating rice is lower than the international standard.

Rice is a staple food for Taiwanese. According to statistics, Taiwanese between the ages of 19 and 62 eat an average of 62 kilograms of white rice a year, while the average annual consumption of all citizens is 47.5 kilograms of white rice, which is much higher than that of other kinds of food. therefore, it is confirmed that the concentration of arsenic in rice sold in Taiwan is relatively important.

The Food and Drug Administration of the Ministry of Health and Welfare sampled 65 cereal samples and 55 miscellaneous grain samples nationwide in 2013. the results of total arsenic analysis showed that the concentration of total arsenic in brown rice was higher than that in white rice, but the total arsenic concentration in all samples did not exceed the standard value of 1000 μ g / kg (1ppm) for edible rice set by the United Kingdom and Australia.

According to the risk assessment results of the plan, the arsenic intake was 5.41 micrograms per kilogram body weight for 0-3 years old children, 4.61 micrograms per kilogram body weight for 3-6 years old children and 2.14 micrograms per kilogram body weight for adults aged 19-65 years. The arsenic intake of all age groups from eating rice and miscellaneous grains was less than the recommended dose of 15 micrograms per kg body weight per week of the Food and Agriculture Organization of the United Nations (Food and Agriculture Organization of the United Nations,FAO).

How to reduce the risk of dietary arsenic exposure?

Although the total arsenic concentration of locally produced rice and imported rice in Taiwan is lower than that of international rice analysis, and the average exposure dose of each age group is less than the recommended value of the Food and Agriculture Organization of the United Nations, however, extreme diets who consume too much rice may still pose potential health risks to the human body. It is suggested that when purchasing rice or other cereal products, families should take turns to buy products from different brands, different places of origin or different stores, so as to spread the risk. In addition, people are called on to follow the principle of a balanced diet and reduce their long-term intake of a single type of food, so as to reduce the risk of arsenic exposure.

Bibliography

[1] Batista BL, Souza JM, De Souza SS, Barbosa F Jr. Speciation of arsenic in rice and estimation of daily intake of different arsenic species by Brazilians through rice consumption. Journal of Hazardous Materials. 2011; 191: 342-348.

[ILSI Taiwan columnist]

Professor Chen Xiuling

He is currently a professor at the Institute of Food Safety, Hygiene and risk Management of Chenggong University and the deputy director of the Environmental Microtoxicology Research Center of Chenggong University. The research specializes in food safety, risk assessment, environmental health and so on.

Professor Li Junzhang

He is currently a special professor at the Institute of Industrial Health and Environmental Medicine of Chenggong University, director of the Environmental Micro-toxicants Research Center of Chengkung University, and a member of the Taiwan Association of International Life Sciences. The research specializes in environmental toxicant health risk assessment and management, environmental trace toxicant sampling analysis and exposure assessment.

(this article is reproduced from the November 2017 issue of ILSI Taiwan column)

1 mg / kg = 1000 μ g / kg = 1 ppm

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