Regulators have been reluctant to set maximum levels (ML) for arsenic in food because of the molecular diversity of the arsenic species present. Arsenic levels in food can vary by several orders of magnitude, with the arsenic present in many different molecular forms which vary substantially in toxicity. Arsenic in food is found as a multitude of different organoarsenic species and as inorganic arsenic (iAs). iAs is regarded as the most toxic form of arsenic in food and feed and is classified as a carcinogen by the International Agency for Research on Cancer (IARC). Organoarsenic species are, in general, believed to be of low toxicity or even non-toxic, eg, most of the arsenic in fish occurs as non-toxic arsenobetaine.