Halogenated organic compounds (AOX)

AOX, Adsorberbara organiskt bundna halogener


Halogenated organic compounds (as AOX)

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 Halogenated organic compounds are substances that contain carbon and hydrogen, but where one or more hydrogen atoms have been replaced by a halogen – chlorine, bromine, fluorine or iodine.1 AOX is short for “adsorbable organic halides” and is a measure of the collected presence of all organically bound halogens in a sample. It is a mix of several hundreds of substances with different stability and degradability.2


AOX is used as a measure of the presence of organically bound halogens in a sample.

Sources and transportation pathways

The most important source of AOX in the environment is the use of chlorine within the pulp and paper industry. Other industries such as the chemical industry, waste management and wastewater treatment are potential sources of AOX to water. Smaller amounts of AOX may also arise during routine chlorination (disinfection) of drinking water and swimming pools.3

Effects on environment and health

The effects on the environment and health depends on the substance. Many halogenated organic substances are not readily degradable and are harmful to the environment. Some are toxic to aquatic organisms even at low concentrations. These substances may also be persistent and tend to bioaccumulate in the environment.4

International agreements and regulations

The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on emissions of AOX is made available.


1 https://www.havochvatten.se/funktioner/ordbok/ordbok/g---i/ordbok-g-i/2013-03-14-halogenerat-organiskt-amne.html
2 https://www.eea.europa.eu/help/glossary/eper-chemicals-glossary/halogenated-organic-compounds-aox
3 http://apps.sepa.org.uk/spripa/Pages/SubstanceInformation.aspx?pid=143
4 http://apps.sepa.org.uk/spripa/Pages/SubstanceInformation.aspx?pid=143