Perchlorates are salts of perchloric acid HClO4. Perchlorate occurrences in the environment are mainly of anthropogenic origin, i.e. they are caused by humans, although perchlorate can also occur naturally in mineral storage sites in several countries. Perchlorate has never been approved as a pesticidal or biocidal active substance in the European Union. According to the latest findings, the main entry path is probably the contact of foods in the course of their production and/or processing with water which has been treated previously with chlorinated biocidal products for disinfection purposes. Perchlorate can occur as a by-product of disinfection when used in this way.