2-(2H-Benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study planned

Justification for type of information:

TESTING PROPOSAL ON VERTEBRATE ANIMALS
[Please provide information for all of the points below. The information should be specific to the endpoint for which testing is proposed. Note that for testing proposals addressing testing on vertebrate animals under the REACH Regulation this document will be published on the ECHA website along with the third party consultation on the testing proposal(s).]

Tinuvin 928, indicates a potential risk of bioaccumulating due to a calculated high log Pow of 8.82 at 25°C. This substance was also discussed in the 27th PBT expert group meeting at ECHA where it was said that further refinement of the B assessment is needed for Tinuvin 928.


NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on which testing is proposed to be carried out: 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)- Phenol
- common name: Tinuvin 928
CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- Available GLP studies: An experimental GLP study in accordance with OECD Guideline 305 C, conducted for the Japanese authorities in 1999 (Document ID: G4-9924C106CP; sponsored by CIBA specialty chemicals, Japan) is existing. The calculated BCF factors were less than 27 times and less than 6 times at nominal concentrations of 0.05 and 0.5 mg/L, respectively. Under the conditions of this study, the test item was reported as not bioaccumulative in carp. As the water solubility of the compound was determined to be <0.069 mg/L only the lower concentration group of 0.05 mg/L might be below the solubility limit of the compound and thus not underestimating the final BCF. Although the study was conducted with solubilizer and is not fully reliable, it is a good indication that Tinuvin 928 is not bioaccumulative.
- Available non-GLP studies: there are no non-GLP studies
- Historical human/control data: no data are available
- (Q)SAR: The approach of estimating the bioaccumulation potential in aquatic species via QSAR with Catalogic (v5.11.19) predicted a BCF factor (all mitigating factors applied) of 20.4 L/kg. The approach was abandoned since Tinuvin 928 was only within the parameter domain, meaning that the substance was within the logKow, molecular weight and water solubility ranges of the parameter domain and within the mechanistic domain but not within the other applicability domains of the model.
A EPISuite v4.11 QSAR predicted a BCF value from regression-based method of 1019. This value is below the bioaccumulation criterium of 2000 and within the estimation domain with its logKow and molecular weight, indicating that Tinuvin 928 is not bioaccumulative.
- In vitro methods: no data are available
- Weight of evidence: Although there is preliminary good evidence to show that Tinuvin 928 is not bioaccumulating, shown in an available GLP-study or in the QSAR, it is necessary to conduct another study for definitive confirmation.
This substance was also discussed in the 27th PBT expert group meeting at ECHA where it was said that further refinement of the B assessment is needed for Tinuvin 928.

- Grouping and read-across: By looking at other UV absorbers of the hydroxyphenyl benzotriazole class, some of the chemicals fulfils the bioaccumulation criteria with a bioaccumulation factor in aquatic species higher than 2000, the other substances do not. Together with structural differences, a prediction for Tinuvin 928 by a conclusion by analogy is not possible.

- Substance-tailored exposure driven testing [if applicable]: not applicable
- Approaches in addition to above [if applicable]: not applicable
- Other reasons [if applicable]: not applicable

CONSIDERATIONS THAT THE SPECIFIC ADAPTATION POSSIBILITIES OF ANNEXES VI TO X (AND COLUMN 2 THEREOF) OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
Tinuvin 928, indicates a potential risk of bioaccumulating due to a calculated high log Kow of 8.82 at 25°C. Furthermore, it was showed in the Japanese GLP-study that the substance was accumulated to a small degree, therefore Tinuvin 928 has a certain potential to cross biological membranes. Also, the direct and indirect exposure of the aquatic compartment cannot be ruled out.

Tinuvin 928 is not readily biodegradable by OECD criteria. Furthermore, the degradability of the substance was assessed with Catalogic v5.11.19, Catalogic 301 C v09.13 to identify possible degradation products, whose majority cannot be regarded as readily biodegradable either, showing BOD values of <20%. The parent and part of its metabolites are regarded as persistent in the environment. With the P-criterion fulfilled, it is now necessary to concentrate on the B-criterion with a new vertebrate study.


FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design / methodology proposed: The compound has a low water solubility and a high adsorption potential. Due to these properties the feasibility of a bioaccumulation test according to OECD guideline 305 with aquatic test substance exposure is technically challenging. Despite these difficulties the registrant favors the aquatic exposure study over the performance of a dietary study for reasons of comparability and due to the missing regulatory trigger values for data derived from a dietary bioaccumulation test (OECD 305 as dietary study). However, if the aquatic exposure route is technically not feasible or the possible results scientifically difficult to interpret, a dietary bioaccumulation test according to OECD guideline 305 will be performed.

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 (Bioaccumulation in Fish: Aqueous and Dietary Exposure) -I: Aqueous Exposure Bioconcentration Fish Test

Description of key information

Although there is preliminary good evidence to show that Tinuvin 928 is not bioaccumulating, shown in a supporting Japanese study or in the QSAR, it is necessary to conduct another study for definitive confirmation. This substance was also discussed in the 27th PBT expert group meeting at ECHA where it was said that further refinement of the B assessment is needed for Tinuvin 928.

 

Additional information

Tinuvin 928, indicates a potential risk of bioaccumulating due to a calculated high log Pow of 8.82 at 25°C. This substance was also discussed in the 27th PBT expert group meeting at ECHA where it was said that further refinement of the B assessment is needed for Tinuvin 928.

 

An experimental GLP study in accordance with OECD Guideline 305 C, conducted for the Japanese authorities in 1999 (Document ID: G4-9924C106CP; sponsored by CIBA specialty chemicals, Japan) is existing. The calculated BCF factors were less than 27 times and less than 6 times at nominal concentrations of 0.05 and 0.5 mg/L, respectively. Under the conditions of this study, the test item was reported as not bioaccumulative in carp. As the water solubility of the compound was determined to be <0.069 mg/L only the lower concentration group of 0.05 mg/L might be below the solubility limit of the compound and thus not underestimating the final BCF. Although the study was conducted with solubilizer and is not fully reliable, it is a good indication that Tinuvin 928 is not bioaccumulative.

The approach of estimating the bioaccumulation potential in aquatic species via QSAR with Catalogic (v5.11.19) was abandoned since Tinuvin 928 is not within of the whole applicability domain of the model. A EPISuite v4.11 QSAR predicted a BCF value from regression-based method of 1019. This value is below the bioaccumulation criterium of 2000 and within the estimation domain with its logKow and molecular weight, indicating that Tinuvin 928 is not bioaccumulative.

By looking at other UV absorbers of the hydroxyphenyl benzotriazole class, some of the chemicals fulfils the bioaccumulation criteria with a bioaccumulation factor in aquatic species higher than 2000, the other substances do not. Together with structural differences, a prediction for Tinuvin 928 by a conclusion by analogy is not possible.

 

Although there is preliminary good evidence to show that Tinuvin 928 is not bioaccumulating, shown in a supporting Japanese study or in the QSAR, it is necessary to conduct another study for definitive confirmation.

 

Tinuvin 928 is not readily biodegradable by OECD criteria. Furthermore, the degradability of the substance was assessed with Catalogic v5.11.19, Catalogic 301 C v09.13 to identify possible degradation products, whose majority cannot be regarded as readily biodegradable either, showing BOD values of <20%. The parent and part of its metabolites are regarded as persistent in the environment. With the P-criterion fulfilled, it is now necessary to concentrate on the B-criterion with a new vertebrate study.