Perchlorate in food Questions and answers about origin and health risks

Perchlorates are salts of perchloric acid (HClO₄), which consist of the perchlorate anion (CIO₄^-) and various cations. Well-known perchlorate compounds include ammonium perchlorate and various metal salts (barium, potassium, lithium, magnesium and silver perchlorate). It is not known which perchlorate compounds were found in the foods in which perchlorate was measured.

Perchlorate is mostly of anthropogenic origin, i.e. produced by humans, but it can also occur naturally. In some countries, such as Chile, perchlorates occur naturally in higher concentrations in the soil. Chile saltpetre, which is used as a fertiliser, may contain perchlorate. Perchlorates are also used as industrial chemicals, particularly as rocket propellants and in fireworks, as well as in medical drugs. They can also be formed by oxidative processes in the atmosphere or in small amounts when disinfectants containing chlorine are used. Perchlorates are currently not authorised for use as plant protection products (PPPs) or biocidal active substances in the EU.

According to current knowledge, perchlorates enter food primarily through contact with water that has been treated with biocidal products containing chlorine. Perchlorate can form as a by-product when such products are used. Residues can remain on surfaces or equipment after cleaning or disinfection and enter food in this way. Water is also added to some foods during production.

Perchlorate can also pass from fertilisers into plants and thus into plant-based foods, where it is transported in particular to the leaves. According to the EU Fertiliser Products Regulation, the perchlorate content of inorganic macronutrient fertilisers must not exceed 50 milligrams (mgshort formilligram) per kilogram (kgshort forkilogram) of dry mass. Perchlorate can also enter the environment and subsequently food through its use in industrial chemicals, rocket fuels or fireworks.

Repeated intake of perchlorate can inhibit iodine absorption and possibly lead to deficiency symptoms. This inhibition can cause temporary changes in thyroid hormone levels in risk groups. People with thyroid disorders or iodine deficiency as well as newborns and children may be particularly affected by adverse effects. Pregnant women with pre-existing thyroid dysfunction are another vulnerable group. However, the inhibition of iodine uptake by perchlorate is not permanent: if perchlorate is no longer ingested, iodine uptake returns to normal after some time.

For perchlorate, EFSAshort forEuropean Food Safety Authority has derived a tolerable External Link:daily intake (TDI) of 0.0014 milligrams (mgshort formilligram) per kilogram (kgshort forkilogram) of body weight, based on inhibition of iodine uptake in healthy adults. EFSAshort forEuropean Food Safety Authority considers acute health risks from a single intake of perchlorate in food to be unlikely. Therefore, EFSAshort forEuropean Food Safety Authority has not derived an acute reference dose (ARfDshort forAcute Reference Dose).

Maximum levels for perchlorate are regulated EU-wide by contaminant legislation. Regulation (EU) 2020/685 sets specific maximum levels for perchlorate in various product groups such as fruit and vegetables, tea, herbal tea and infant formula. 

Based on the evaluated data on the occurrence of perchlorate in food, EFSAshort forEuropean Food Safety Authority concludes in its opinion that a single intake of perchlorate at concentrations measured in food to date is unlikely to cause adverse health effects. However, repeated intake of perchlorate may give rise to concerns about associated health risks, particularly for infants who are breastfed by mothers with iodine deficiency or who ingest perchlorate residues via infant formula. This applies even after two weeks of (short-term) exposureClose dialogexposureExposureTo glossary to perchlorate. Perchlorate levels in food should therefore comply with the maximum levels set and be as low as possible overall.

Perchlorate residues have been measured in food from numerous countries of origin, including fruit and vegetables from Germany.

Consumers should eat a balanced and varied diet. The health benefits of fruit and vegetables remain undisputed.