Perchlorates are salts of perchloric acid. They are water-soluble and relatively stable. They are persistent in the environment and considered ubiquitous environmental contaminants. The presence of perchlorates in the environment can be traced back to both natural and anthropogenic sources, such as the use of natural fertilizers or industrial emissions, but they can also form naturally in the atmosphere and in surface water. As opposed to some chlorates, salts of chloric acid, perchlorates were never approved for use as active substances for pesticides or biocides in the European Union (EU), although chlorates are also no longer approved as a pesticide active substance since 2008. Both chlorates and perchlorates can be generated when chlorine, chlorine dioxide, and hypochlorite are used in order to disinfect water. This is done in order to prevent water in cisterns and pipelines from becoming infested with germs before being used to irrigate crops for human consumption. Even water that is used for food production can be chlorinated. Subsequently, chlorate residue can end up in and on the final product in a variety of ways.
This represents a problem from a toxicological perspective, because both chlorates and perchlorates can inhibit iodine uptake in the thyroid. Although this inhibitive effect is reversible, long-term intake can lead to disruptions in the production of thyroidal hormones and to an enlarged thyroid. Based on this information, the European Food Safety Authority has published a reference dose as a basis for chronic risk assessment. The tolerable daily intake (TDI) was set at 0.3 µg/kg bodyweight per day.
In addition to the TDI, there are new maximum residue levels for chlorate in food since the Regulation (EU) 2020/749 went into effect on June 28th, 2020. These maximum levels are valid for all types of products, in accordance with Annex I of the pesticide regulation (EC) No 396/2005. The regulation is effective immediately, without any grace period, and thus also retroactively applies to products that had been produced or imported to the EU before that date. There are also new maximum levels for perchlorate in certain food groups in effect since July 1st, 2020. In May 2020, the European Commission announced the Regulation (EU) 2020/685, amending the Regulation (EC) No 1881/2006, with a grace period. The grace period is valid for all food products that were brought onto the market before July 1st, 2020. These are allowed to be sold until their best-before date or use-by date.
The analysis of perchlorate and chlorate by means of LC-MS/MS technology has been successfully established as part of the GBA Group’s routine analysis. If you have any questions about the legal situation or analysis of these compounds, we will gladly assist you.