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The ready biodegradability on 2212 -81 -9 was evaluated in a study performed in accordance with OECD testing guideline 301 D and GLP requirements.

The test substance is not biodegraded in the closed bottle test, and thereforeshould not be classified as readily biodegradable. This lack of biodegradation is not due to toxicity of the test compound because the endogenous respiration is not inhibited by bis (tert-butyl peroxy isopropyl) benzene.

Based upon the adsorption potential of the substance of interest,a study was conducted to determine the biodegradation of the read across source [1,3(or 1,4)-phenylenebis(1-methylethylidene)]bis[1,1-dimethylethyl], peroxide, CAS 25155 -25 - 3in water/sediment simulation test, according to US EPA guideline.The substance was not found in the water layers at all time points. In the sediment layer, an average of 94.7% of the applied dose was detected at day 0. The substance has decreased to an average of 9.7% of the applied dose at day 90. The half-life in sediment/water compartment under anaerobic conditions was determined as 29 days.Tert-butanol, the main expected breakdown product, was detected in water and sediment layers at all time point (except day 0) but below a quantifiable level until day 90: it represented an average of 61.5% of the test substance applied dose.

A mineralization test in surface water (OECD 309) was conducted on the read across source25155 -25 -3. The test system was not suitable for the test substance as the test material leaved the test system and hence, the study did not meet the validy critera for the test guideline as viable samples did not achieve acceptable mass balance. Due to the poor mass balance and the inability to allow sufficient contact time for biodegradation to occur due to the volatility, the test is concluded as unsuitable for the substance. Based on the study it is not possible to draw any conclusions with regards to surface water degradation. Hence, a OECD 308 test was initiated and the performed feasibility study shows that the sediment test is feasible for the substance.

Thewater/sediment simulation test, according to US EPA guideline was considered to not reflecting environmental conditions.The risk assessment also shows that sediment is the most relevant compartment,therefore a new study was started according to theOECD 308 guideline.

A feasilbility study for aquatic sediment was performed. The results of the study demonstrate the feasibility of conducting a full OECD Guideline 308 study to investigate degradation of 1,3-bis(tert-butylperoxy isopropyl)benzene and 1,4- bis(tert-butylperoxy isopropyl)benzene in the aerobic and anaerobic aquatic sediments.

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