Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Endpoint summary

Administrative data

Description of key information

Additional information

A BCF of 924.7 l/kg is estimated on the basis of log Pow of 5 using the EPI Suite program, v.4.11. This is indicating that CBS is bioaccumulative.


In order to fulfill the information requirements especially for the PBT properties of CBS, the registrant proposes to perform a bioaccumulation test according to OECD guideline 305 dependent on the outcome of the assessment of the P criterion. For this reason, the Registrant has already proposed to first perform a simulation study in soil.
1. If the outcome of the preceding simulation test leads to the conclusion that CBS is P/vP, a bioaccumulation test shall be performed.
2. If the conclusion is not P/vP, a bioconcentration test shall not be performed.


Should establishing stable conditions for CBS not prove feasible owing to the hydrolytic behaviour of CBS, the test will be performed with a degradation product which is potentially found to be P/vP in the soil simulation test and if it fulfills the screening criterion for the B assessment.


According to EU-Risk Assessment from 2008, the described degradation products of CBS, MBT, BT, BTon, MBTS, MeSBT and MeBT are not bioaccumulative (BCF< 100). EU risk assessment 2008 reported a BCF of 3094 l/kg estimated by the equation log BCF = 0.85 log Pow - 0.70 (Veith et. al, 1979) with a log Pow of 4.93. This estimation is not taken into accout in current assessment, due to its limited training sets with only 55 diverse chemicals and its probabaly too broad application range of log Pow. The BCFBAF v3.02 from EPIWIN v4.11 was used instead as the most updated estimation program with more than 400 training sets. On the other hand, considering the fast hydrolysis property of CBS and the low bioaccumulativity of the metabolites, CBS should not be taken as PBT candidate.