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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Administrative data

Link to relevant study record(s)

Description of key information

The in vitro rate of metabolism was determined for [1,3(or 1,4)- Phenylenebis(1-methylethylidene)] bis[tert-butyl] peroxide using the in vitro metabolism trout liver S9 assay (OECD Test Guideline 319B, adopted in June 2018).


This organic peroxide metabolized rapidly under biologically active conditions with a metabolic half- life of 67 minutes or 1.13 hours. This data was used to extrapolate in vivo rate constants of metabolism or kMETof 0.184 day-1or 0.475 day-1using hepatic portal blood flow or hepatic portal and arterial blood flow, respectively. The use of these kMET values in conjunction with the Gobas model dropped the calculated BCF from 45,294 kg day-1(assuming no metabolism) to 536 or 209 kg day-1. The impact of metabolism on [1,3(or 1,4)- Phenylenebis(1-methylethylidene)] bis[tert-butyl] peroxide drops the BCF to less than the action level of 2000 (Reach Criteria) and should not be considered to have significant bioaccumulation potential.


A bioaccumulation in fish study according to the OECD 305 using the aqueous exposure was performed under flow-through conditions. The results are based on the time-weighted average based on the recommandation of the Echa decision. Based on this, the steady-state BCFss is equal to 1114 L/Kg and the steady-state BCFss normalised to a fish lipid content of 5% is equal to 1944 L/Kg.The lipid normalised and growth corrected kinetic BCFkLg value is equal to 2103 L/kg. 




Key value for chemical safety assessment

BCF (aquatic species):
2 103 L/kg ww

Additional information