Bis(α,α-dimethylbenzyl) peroxide

Biodegradation in water: screening tests

Description of key information

In a manometric respirometry test average mineralisation rates of 20 % (at 100 mg test substance/L) and 44 % (at 20 mg test substance/L) were determined, however with high variability between replicates. Furthermore, in a prolonged closed-bottle test dicumyl peroxide was degraded by 18 % after 28 days and by 60 % after 57 days. Therefore, ultimate degradation of dicumyl peroxide has been demonstrated, but the criteria for being regarded as readily biodegradable are not fulfilled.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, not fulfilling specific criteria

Additional information

Several studies are available investigating the potential of dicumyl peroxide for ready biodegradability. The most recent and reliable study, following OECD guideline 301F (manometric respirometry test) identified mineralisation rates after 28 days of, on average, 20 % at a test substance concentration of 100 mg/L, and of 44 % at 20 mg/L, however with high variability. Accordingly, although dicumyl peroxide fails the criterion for being regarded as “readily biodegradable” the test result shows that the substance is susceptible to mineralisation by biological processes.

In a previous study according to OECD guideline 301 D (closed bottle test) dicumyl peroxide was not biodegradable after 28 days, but biodegradation was observed in a prolonged test for up to 57 days. This study is considered to be of limited reliability since employing an unsuitably high nominal test concentration (1000 mg/L) and lacking a toxicity control. Nevertheless, also this somewhat deficient study confirms the potential of dicumyl peroxide for biological degradability.

In conclusion, the available screening test results strongly suggest that dicumyl peroxide is prone to biological degradation, but cannot be identified as readily biodegradable. Although no tests on inherent biodegradability are available, the currently existing information supports classification of dicumyl peroxide as “inherently biodegradable”, however without fulfilling specific criteria (since this cannot be evaluated due to lack of a true inherent test).