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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data from structural related substance
Reason / purpose:
read-across: supporting information
Principles of method if other than guideline:
MITI Bioaccumulation. Studies conducted in accordance with generally accepted scientific principles.
GLP compliance:
yes
Test organisms (species):
Cyprinus carpio
Details on test conditions:
28days-6weeks
Remarks on result:
other: Due to fast hydrolysis, only BCF of degradation products are relevant for risk assessment of TBBS in environment. The experimentally determined BCF of MBT is <8, of tert-butylamine <9; TBBS is considered to have very low potential for bioaccumulation.

N-tert-butylbenzothiazole-2-sulphenamide (TBBS) hydrolyses in water to produce 2 -mercaptobenzothiazole, and tert-butylamine.

These hydrolysis products have been tested and shown to have low potential for bioaccumulation. Based on these findings, TBBS is judged to have low potential for bioaccumulation also.

Bioconcentration factors of identified metabolites:

2-mercaptobenzothiazole (CAS No. 149 -30 -4):

Level 1 : < 0.8 (nominal concentration = 100 µg/L)

Level 2 : < 8 (nominal concentration = 10 µg/L)

tert-butylamine (CAS No. 75 -64 -9):

Level 1 : 0.86 (nominal concentration = 1 mg/L)

Level 2 : 9.0 (nominal concentration = 0.1 mg/l)

Validity criteria fulfilled:
not specified
Conclusions:
Due to the fast hydrolysis, only the BCF of the degradation products are relevant for risk assessment of TBBS in the environment. The experimentally determined BCF of MBT is lower than 8 and the one of tert-butylamine lower than 9; and hence TBBS is considered to have very low potential for bioaccumulation.
Executive summary:

Due to the fast hydrolysis, only the BCF of the degradation products are relevant for risk assessment of TBBS in the environment. The experimentally determined BCF of MBT is lower than 8 and the one of tert-butylamine lower than 9; and hence TBBS is considered to have very low potential for bioaccumulation.

Description of key information

TBBS has a hydrolysis half life of 9.53 h at pH7 (25°C) and therefore hydrolysis is a significant factor in the aquatic environment. According to REACH Guidance Document R.7c (2014, p. 26) it can be assumed that the rate of hydrolysis is greater than that for uptake by the exposed organisms. In these cases, it may sometimes be appropriate to perform a BCF test on the hydrolysis products, if identified, instead of the parent substance. In case of TBBS MBT and tert-butylamine are identified hydrolysis products for which bioaccumulation tests are available. The experimentally determined BCF of MBT is lower than 8 and the one of tert-butylamine lower than 9; and hence MBT and tert-butylamine and therefore also TBBS are considered to have very low potential for bioaccumulation (MITI, 2000 and 2003).

Key value for chemical safety assessment

Additional information