Aspects to be considered for waste classification

For a decision between the MH and the MNH entry in the field of organic peroxides, hazardous properties HP 1 and HP 3 are most relevant. In the determination of HP 1 ‘Explosive’ (Annex 3, Section 3.1), cut-off values for organic peroxides need to be considered. A waste containing organic peroxides classified with hazard statement class H240 or H241 needs to be assessed for HP 1, unless the following statements hold true: — No other hazardous substances assigned hazard statement codes listed in Table 8 (see Annex 3, Section 3.1) are present, and — One of the following two criteria is met: — the waste contains >1 % but ≤ 7 % hydrogen peroxide, and the available oxygen content (Oi) of the organic peroxide(s) is ≤ 0,5 %; — the waste contains ≤ 1 % hydrogen peroxide, and the available oxygen content (Oi) of the organic peroxide(s) is ≤ 1 %. The available oxygen content, Oi (%) for any given organic peroxides has to be calculated according to section 2.15 of Annex I to the CLP Regulation: Oi (%) = Σ (16 × (ni × ci / mi)) where: ni: number of peroxygen groups per molecule of organic peroxide i. ci: concentration (mass %) of organic peroxide i in the waste. mi: gram molecular mass of organic peroxide i ‘Σ’ means that if a waste contains more than one organic peroxide the available oxygen from each is added together. This includes all organic peroxides, and is not restricted to those classified as H240 or H241. The UK Guidance provides an example calculation for methyl ethyl peroxide which is presented in the following. A waste contains 2,9 % methyl ethyl peroxide (C2H5-O-O-CH3) and 3 % hydrogen peroxide. The concentration of hydrogen peroxide is > 1 % and ≤ 7 % (see criteria above). Methyl ethyl peroxide has a molecular mass of 76 g (so ‘mi’ is 76) and one peroxide functional group present (so ni is 1). When applying these values in the the formula ‘Oi (%) = Σ (16 × (ni × ci / mi))’ for a concentration (‘ci’) of 2,9 % in the waste, methyl ethyl peroxide has an available oxygen content (Oi) of 0,61 % (16 × 1 × 2,9 / 76). This is above the available oxygen threshold of 0,5 % for criterion (i), so HP 1 must be assigned. Organic peroxides have specifically to be considered in determining HP 3 ‘Flammable’. A waste containing self-reactive substances or organic peroxides classified as H240 or H241 may possess the hazardous property HP 3 Flammable as a result of the assessment of HP 1 Explosive classifying the waste as a whole as H242. Please refer to Section 3.3 for additional information. Further guidance on organic peroxides according to the CLP Regulation can be found directly in the CLP Regulation or in its corresponding technical guidance note (hereinafter ‘the ECHA CLP Guidance’) (29).

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Source: EUR-Lex (Cellar) · retrieved 2026-09-07