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The European Organic Peroxide Safety Group

EOPSG, a Sector Group of Cefic

The aim of the European Organic Peroxide Safety Group (EOPSG) is to promote the safe handling of Organic Peroxides. To this end, EOPSG establish safe working practices, review relevant upcoming legislation, suggest improvements, generate safety data and suggest new or improved test methods for organic peroxides.

EOPSG was founded by ARKEMA, NOURYON, PERGAN and UNITED INITIATORS. Since the late sixties, EOPSG actively generates product safety data and promotes safe transport and storage of organic peroxides. After being a stand-alone group for so many years, EOPSG became a sector group of Cefic in 2021.


Organic peroxides are essential ingredients in a variety of polymer and construction materials, helping to produce them, improve their properties, and make them easier to process or recycle. Because of their chemical characteristics, safety is of utmost importance.

organic peroxides GHS class 5.2 label

General properties of organic peroxide

Organic peroxides are liquid or solid organic substances which contain the bivalent -O-O- structure. The term organic peroxide includes organic peroxide mixtures (formulations) containing at least one organic peroxide. The -O-O- bond is a relatively weak one which will cleave easily at relatively low temperatures in comparison with other chemicals usually applied in industry. On one hand the tendency to cleave the -O-O- bond easily forming radicals gains the unique reactivity properties of organic peroxides as initiator in polymerisation reactions.


On the other hand, this characteristic property constitutes the main hazard aspect of organic peroxides; they are in general thermally unstable and highly reactive. At too high temperatures, this will result in an uncontrolled decomposition reaction, a so called self-accelerating decomposition, which leads to fast evolution of heat and gases. However, the rating of this hazard depends strongly on the type of organic peroxide and varies strongly with its concentration and formulation.


In addition, organic peroxides may be flammable and burn rapidly, may be sensitive to impact or friction, may react dangerously with other substances and may have toxic, eco-toxic and corrosive properties.

Founding members of the European organic peroxides safety group



  • ACC - OPPSD: Organic Peroxide Producers Safety Division of the American Chemistry Council


This website, including the documents therein, is intended for information only and sets out recommendations on risks and precautions to be considered when handling, storing and transporting organic peroxides. The information contained in this website and its documents is provided in good faith and, while it is accurate as far as the authors are aware, no representations or warranties are made about its completeness. It is not intended to be a comprehensive overview of all detailed aspects of organic peroxides safety matters. No responsibility will be assumed by Cefic or the EOPSG members in relation to the information contained in this website and its documents.

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