Analysis of organic and inorganic arsenic in food

NEW: Small organoarsenic species

In July 2024, EFSA extended its assessment of arsenic compounds with an opinion on small organoarsenic compounds^[1a]. Main subject of this opinion are monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). In addition to the determination of inorganic arsenic, our newly implemented IC-ICP-MS coupling already enables the analysis of MMA and DMA in the above-mentioned food matrices. An extension to other food groups is in progress.

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.

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 new opinion published early in 2024, 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].

The small organoarsenic compounds MMA and DMA were assessed in the new EFSA opinion using the Margin of Exposure (MOE) approach. Based on the available data, no health concerns could be derived for MMA, regardless of the age and consumer group. However, DMA increases the occurrence of urinary bladder tumors in animal experiments and was also identified as probably genotoxic.

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, which are so far considered to be of low toxicity. MMA and DMA are likewise ingested via fish and fish products, but also play a role as a source of exposure for DMA.

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.