User Guide to Thresholds and Classification - Environmental ...

91User Guide for Thresholds and ClassificationsConsideration of the stability of a substance should take account of information on such hazards.7.6.2. Classification criteria for organic peroxides – subclass 5.2IntroductionThe following classification system applies to a substance with oxidising properties that meets any of thecriteria for an organic peroxide set out in the Hazardous Substances (Minimum Degrees of Hazard)Regulations 2001, as described above. Where a substance satisfies the criteria for being above thethreshold, the EPA may require additional information to help it to identify and assess the degree and natureof its oxidising property or capacity to oxidise.The principal oxidising hazards arise from the ability of organic peroxides to ignite or cause fire orcombustion, sometimes with explosive force, and sometimes only on exposure to air or water or ambienttemperatures. Organic peroxides may be thermally unstable or self-ignite, and this may release sufficientenergy and products to sustain or promote a chemical decomposition that is hazardous.The classification of an organic peroxide generally follows the degree to which these effects are observed tooccur. The process is set out in Figure 7.1 and the criteria are summarised in Table 7.2. From Figure 7.1, itcan be seen that each classification category may be achieved by various combinations of test results.Mixtures containing organic peroxides, including those using desensitising agents, are also subject toclassification according to these criteria.January 2012 EPA0109