Arsenic is a semimetal that is known primarily for its toxicity. Arsenic can enter plant foods via environmental influences. Comparatively high levels are found in rice and subsequently in products made from rice (rice milk, rice wafers, etc.).

In nature, arsenic occurs as a component of many minerals and enters the atmosphere through volcanic eruptions, for example. However, arsenic is also released by mining, metal industry and combustion of fossil fuels (coal, petroleum). In the past, arsenic was also used in the production of pesticides, fertilizers and wood preservatives. This use is now banned.

Arsenic occurs in different forms (inorganic and organic), which are toxic in different ways. The more toxic form, inorganic arsenic, is predominantly found in soil, while organic arsenic compounds are predominantly found in water. Arsenic is also present in cigarette smoke.

Arsenic in food

Since arsenic is a natural component of the earth's crust, it is found in the soil, water and air. Arsenic also enters the environment through exhaust fumes, wastewater, and human use, and leaching from arsenic-containing ores can cause it to enter groundwater.

Arsenic can get into plant foods due to arsenic content in the soil, atmosphere, or water used for irrigation. Rice may contain more arsenic in inorganic form than other plant foods. The arsenic content in rice varies depending on the arsenic content of the soil and water in the growing region, and also depends on the method of cultivation and the variety of rice. For example, if the fields are flooded during cultivation, this leads to a higher availability of arsenic in the soil. If the irrigation water also has high arsenic levels, the amount of arsenic in the rice grains increases.

Algae, fish and seafood take up arsenic through the water, with mainly organic arsenic compounds being accumulated.

Inorganic arsenic is toxic and carcinogenic. Ingested arsenic enters all organs of the body. If inorganic arsenic is ingested over a long period of time, then it can contribute to the development of diseases: These include skin damage, heart disease, and various cancers such as bladder and lung cancer. During pregnancy, arsenic can be transferred from the mother to the growing child.

Inorganic arsenic is regulated by law in Regulation (EU) 2023/915. On March 3, 2023, in addition to the maximum levels already set for rice and rice products, maximum levels were also set for other product groups in the supplementary Regulation (EU) 2023/465.

As part of the official control, the regulated product groups are checked for compliance with the statutory arsenic maximum levels. In 2019, there was a focus action on buffer products, in which 17 samples of rice wafers were tested for inorganic arsenic. There was no objection in any sample, and all were below the maximum level. From 2015 to 2018, a total of 81 rice and rice products were analyzed for inorganic arsenic. Of these, 21 were basmati rice, 1 purple rice, 1 black rice, 5 jasmine rice, 4 cooked bag rice, 10 long grain rice, 2 dairy rice, 6 parboiled rice, 1 rice cookie, 2 rice noodles, 8 rice wafers, 2 whole grain rice wafers, 5 risotto rice, 10 whole grain rice and 3 wild rice. The studies revealed average levels of inorganic arsenic of 0.089 mg/kg food. Only one sample of whole grain rice exceeded the maximum inorganic arsenic level of 0.25 mg/kg allowed for whole grain rice, with a concentration of 0.301 mg/kg.

Our studies during 2007-2014 revealed high average levels of inorganic arsenic in seaweed (1,901 µg/kg) and rice (101 µg/kg). In the "fish and seafood" group, high average levels of total arsenic were measured, but the levels of inorganic arsenic were low (31 µg/kg).

In other international studies, significantly higher levels of inorganic arsenic were detected in rice products, such as rice wafers, rice porridge and rice drinks, compared to rice, although the cause remains to be clarified(BfR, 2015).

The arsenic content in rice can also be reduced by washing with water before cooking or steaming (EFSA, 2015). Excess water should be poured off after the cooking process.

In principle, the diet should be varied. This also applies to cereal products. Since rice in particular has higher arsenic levels, other cereals such as wheat (bulgur, cous cous), rye, oats, spelt, green spelt, rolled barley or gluten-free alternatives such as millet, corn and the pseudocereals buckwheat, quinoa, amaranth or potatoes should be eaten for variety.

Rice products such as rice wafers, rice porridge and rice drinks should only be consumed occasionally and not daily in the interests of preventive health protection. Nevertheless, rice should remain part of a varied diet.

Inorganic arsenic has been classified by the International Agency for Research on Cancer (IARC) as Group 1 "carcinogenic to humans", as an association between a high intake of inorganic arsenic and skin, lung and bladder cancer has been demonstrated. The European Food Safety Authority (EFSA) established different benchmark doses (BMDL01 values) in the range of 0.3 - 8 µg/kg body weight (bw)/day for risk characterization and calculation of the MOE (Margin of Exposure). The MOE value is the ratio between the dose at which a small but measurable adverse effect can be detected (reference point - BMDL) and the total intake for consumers.

Risk assessment 2015

We analyzed a total of 1,080 samples for total arsenic during the period January 2007 - June 2014. However, it is important to differentiate the individual arsenic species because the different species have different toxicity (inorganic arsenic is more toxic than organic arsenic). For this reason, EFSA (2009) conversion factors were used to convert the levels of total arsenic to levels of inorganic arsenic. Rice (average inorganic arsenic content 101 µg/kg) and seaweed (1,901 µg/kg) were particularly contaminated with inorganic arsenic. In the "fish and seafood" group, although a high average content of total arsenic was measured, the content of inorganic arsenic was low (31 µg/kg). Intake of inorganic arsenic via various foods was calculated using average levels of inorganic arsenic in foods and average consumption levels of children, women, and men. Rice was identified as the most important intake source of inorganic arsenic for the Austrian population (31% - 36%), followed by the product groups "bread and rolls" and "fruit and fruit products" (10% - 15%).

Based on the currently available data, the following exposure estimate for the Austrian population was obtained: on average, children consume 0.15 µg, women 0.16 µg and men 0.13 µg of inorganic arsenic per kg body weight and day. Frequent eaters of rice and "bread and rolls" or rice and "fruit and fruit products" consume on average 0.29 µg (children), 0.44 µg (women) and 0.39 µg (men) of inorganic arsenic per bw per day.

Thus, the calculated exposure to inorganic arsenic is in the range of BMDL01 values of 0.3 -8 µg/kg bw/day. Therefore, there is little or no MOE present. EFSA also stated in its 2009 exposure assessment that no or only a low MOE is present for inorganic arsenic and concluded that "a risk to some consumers from ingestion of inorganic arsenic via all foods cannot be excluded".