Analysis of inorganic arsenic in rice and cereals

Background and toxicity

Arsenic (As) is a widespread element that occurs in soil, groundwater, plants, seawater and animals due to natural occurrence but also anthropogenic environmental contaminations. Arsenic can be present in organic and inorganic forms. Most organic arsenic compounds are considered of low toxicological relevance, with methylated forms also under scrutiny. In contrast, the inorganic arsenic species (iAs) are classified as carcinogenic. In food and feed, iAs are predominantly bound in the oxidation state +3 (As^III) or +5 (As^V) in thiocomplexes or are present as oxoanions arsenite (As^III) and arsenate (As^V).

In 2009, the European Food Safety Authority (EFSA) established a benchmark dose (BMD) of 0.3 – 8 µg iAs/kg body weight/day for an increased risk of skin, lung and bladder cancer as well as skin lesions^[2]. However, in its new draft update of this opinion published in 2023, a lower reference point (RP) of 0.06 µg iAs/kg body weight/day is already established. According to EFSA, the newly established dose already has a small but measurable adverse effect. In addition to the types of cancer already described in 2009, chronic kidney disease, respiratory disease, spontaneous abortion, stillbirths, infant mortality and neurodevelopmental effects are now attributed to iAs ^[1].

Seafood and fish are the main sources of total arsenic in the human diet and in animal feed. However, in seafood and fish, arsenic is mainly present as organic arsenobetaine and arsenocholine, both being of low toxicity.

The main source of inorganic arsenic intake across all age groups are cereals (especially rice), cereal products, and drinking water. For infants, toddlers, and children, EFSA’s exposure assessment identifies cereal-based foods for infants and young children as well as biscuits, rusks, and cookies for children as most critical^[3].

Dietary intake estimates of iAs for adult average consumers (0.03-0.15 µg iAs/kg body weight/day) are within the range of the new RP; those for adult heavy consumers (0.07-0.33 µg iAs/kg body weight/day) are even above the dose that poses an increased risk of adverse effects^[1].

Regulatory provisions

Regulation (EU) 2023/915^[4] sets maximum levels for inorganic arsenic as the sum of As^III and As^V in rice, rice-based products and fruit juices as well as in food for infants and young children. Furthermore, a maximum level of total arsenic in salt is laid down. However, with its monitoring Recommendation (EU) 2015/1381^[5], the European Commission continues to request its member states to monitor the levels of total arsenic and inorganic arsenic in a wide range of foods.

Maximum levels for total arsenic in certain feed products are set by Directive 2002/32/EG of the European Parliament and the Council^[6] on undesirable substances in animal feed. In addition, Commission Recommendation 2002/C 206/01^[7] calls for explicit monitoring of the presence of inorganic arsenic in individual and compound feed.