Chlorate in fresh produce

Chlorate (ClO3-) is a substance that is formed as a by-product when using chlorine, chlorine dioxide or hypochlorite for the disinfection of drinking water, water for food production or processing and the cleaning of food contact surfaces on equipment (EFSA, 2015). The opinion of a panel of European Food Safety Authority (EFSA) scientists (EFSA, 2015) and routine surveillance of chlorate in produce (Kaufmann-Horlacher, 2015) was that the levels of chlorate in drinking water and in foods were too high and could negatively impact iodine uptake in humans, especially among infants and children. Reduced iodine adsorption has serious heath implications, including lowered red blood cell counts and a changed composition of the components of bone marrow. To take account of the expert opinion, the European Union amended Regulation 296/2005 in June 2020. Regulation 2020/749 revoked historical authorisations for plant protection products (e. g. pesticides) that contained chlorate. Chlorates are by-products of the breakdown of chlorine-based sanitisers and chlorine chemicals used to treat water. Regulation 2020/749 required that there should be careful use of such products to make sure the statutory limits for chlorate are not exceeded. Furthermore 2020/749 adds a new column for MRLs (maximum residue limits) for a number of foods, many of which are fresh fruits and produce. The general approach of the EU is to avoid stipulating an MRL for chlorate concentrations in water used for irrigation and food processing so as not to further complicate an already complex web of legislation relating to potable and process waters. Control of chlorate concentrations is shifted into the next tier of food production and processing, including fresh fruit and vegetables. Crops grown in water treated with chlorine based sanitiser can accumulate chlorate within the tissue of the crop, which has resulted in a number of high chlorate concentrations above the MRL in crops (Garrido et al., 2020).

However, although there are MRLs for produce in 2020/749 there are also some allowances. To take account of the previous regulations relating to potable water and chlorine, a specific allowance for chlorate residues in processed food is established by 2020/749 that relates to Article 2 of Regulation 852/2004. When determining the permitted content of chlorate residues in or on processed food products for Regulation 2020/749, the contributions of additional ingredient chlorate residues can be taken into account. For example, food that has come in contact with products containing legal concentrations of chlorate residues, or that contains ingredients with such residues (such as processing aids or drinking water, used in compliance with the respective legal requirements). The burden of proof regarding the level of those additional contributions lies with food business operators.

Although no maximum levels for chlorate in potable water were set by the European Union (EU) in Regulation 2020/749, the World Health Organisation (WHO) have established guidance (please note, guidance is not a legal limit) for chlorate in potable water of 0.7 mg/L (WHO, 1986).


EFSA panel on contaminants in the food chain. (2015) Risks for public health related to the presence of chlorate in food. EFSA Journal 13, 4135.

Kaufmann-Horlacher, I. (2015). Chlorate residues in plant-based food: an update. Available online. Accession date 2016-04-11.

EFSA Panel on Contaminants in the Food Chain (CONTAM). (2015). Risks for public health related to the presence of chlorate in foods. EFSA Journal 13, 4135.

World Health Organisation (WHO) of the United Nations. (1986). Chlorite and Chlorate in Drinking-water Background document for development of WHO Guidelines for Drinking-water Quality. Available online. Accession date 2016-04-11.

Garrido, Y., Marín, A., Tudela, J.A., Truchado, P., Allende, A. and Gil, M.I. (2020) Chlorate accumulation in commercial lettuce cultivated in open field and irrigated with reclaimed water. Food Control 114, 107283.