1,4-bis[(2,6-diethyl-4-methylphenyl)amino]anthraquinone

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study planned (based on read-across)

Justification for type of information:

EXPERIMENTAL STUDY PLANNED:
According to the REACH Annex IX, Section 9.2, further biotic degradation testing in appropriate compartment shall be performed to investigate further the degradation of the substance and its degradation product to conclude on the persistency of the tested substance.
The following known critical properties of the substances of the category have been considered for simulation testing:
- Mobility: each of the substances of the category have predicted Koc values >> 1,000,000 mL/g (KOCWin v2.00; EPISuite v 4.11) indicating the substances will have a very high affinity to bind to organic matter.
- n-octanol water partition coefficient – each of the substances of the category have predicted or experimental log KOW values >> 4.5 reinforcing the hypothesis that the substances will have a high affinity to bind to organic matter.
- Water solubility –each of the substances have very low water solubility < 20 µg/L.
- Ready biodegradation – screening tests (OECD 301 and 302) confirm that the substances do not fulfill the ready biodegradability criteria.
Based on the profile described above it would be more appropriate to begin simulation tests in compartments where the substances are most likely to have the potential to persist and accumulate in the environment i.e., soil or sediment. Regarding transformation product, the quality of data generated from an OECD Test Guideline (TG) 309 would be more limited than that generated from an OECD-TG 307 or OECD-TG 308. Identification of potential metabolites could be limited as the upper concentration for testing would be restricted <20 µg/L. If the test substance rapidly partitions, as expected, then recoveries in the surface water will likely be Soil represents a “worst-case” in so much as persistence is highly likely to be concluded due to the strong binding to soil (organic matter). The strategy also aligns with Figure R.11-3 which, as mentioned, outlines the testing strategy for persistence assessment (ECHA, R.11, June 2017) where it is sometimes necessary or justifiable to deviate from conducting the OECD-Tg 309 in the first instance, with preference for another compartment if:
- Water compartment is not at all relevant (based on fate and compartment of release),
- Persistence criteria are most likely to be exceeded in sediment or soil,
- High hydrolysis rate etc.
It is intended to support this strategy, where possible, with fate modelling to indicating the significant partitioning of the substances to soil.
Based on the profile of the substances and expected technical challenge in water compartment, it is proposed to start simulation testing in soil compartment with an OECD-TG 307.


NON-CONFIDENTIAL NAME OF SUBSTANCE:
All substances included in the category approach are poorly water soluble with high adsorption coefficient (log Koc>6), high partition coefficient (logKow>6) and not readily biodegradable (see the category approach document for further details).
A testing proposal for soil simulation test is requested on the source substance, Reinblau RLW (CAS n°41611-76-1). This substance is registered as Annex IX and has been chosen as the low limit of the boundary (exp log Kow of 8.6; exp Log Koc of 6.2) of the category group. The latter data are close to Solvent Violet 36 and to Solvent Green 3 for which LANXESS has recently submitted an opt-out dossier. However, the Annex IX registration of Reinblau RLW offers more available data though. This study on Reinblau RLW will be used as a source study for read-across with the other substances of the category (Reinblau BLW, Violet 36 and Green 3) sharing the same metabolic profile from EAWAG model (see category approach document). Indeed, it seems they have a similar pathway predicted for biodegradation model.

CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION :
- Available GLP studies: no data available
- Available non-GLP studies: no data available
- Historical human/control data: not applicable
- (Q)SAR: no data available
- In vitro methods: : not applicable
- Weight of evidence: no data available
- Grouping and read-across : no data available
- Substance-tailored exposure driven testing : not applicable
- Approaches in addition to above: not applicable
- Other reasons: 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:
Under Annex IX, Section 9.2., Column 2 of REACH, further biotic degradation testing in appropriate compartment shall be considered if the chemical safety assessment according to Annex I indicates the need to investigate further the degradation of the substance and its transformation or degradation products. Here, based on the chemical safety assessment and the profile of the substances of the category, an integrated testing strategy has been developed to assess the persistency of the tested substance. It is proposed to start simulation testing in soil compartment with an OECD Test Guideline 307. Depending on the outcome of the soil assessment, further simulation test would be considered at a later stage. In conclusion, Annex IX, Section 9.2., Column 2 of REACH does not allow omitting the need to submit further information on degradation under Column 1.

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
The proposed Aerobic and Anaerobic Transformation in soil test (test method: OECD Test Guideline 307) is appropriate to cover the information requirement for soil simulation testing (ECHA Guidance R.7.9.2.3., June 2017). The soil simulation degradation study should be performed in aerobic conditions according to OECD TG 307 including the determination of the degradation half-lives in 4 different types of soils at environmentally relevant temperatures (by default at 12°C OR 20°C (guideline)). Application rate will not be limited by the poor water solubility of the test substances in an OECD 307 where the application solution(s) can be prepared in solvent. The increased application rate (versus OECD-TG 309) increases the amount of residues available for identification (of transformation product) analysis and therefore increases the potential for successful tentative identifications (of metabolites).
Soil is a compartment of concern where emission cannot be excluded.

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,4-bis[(2-ethyl-6-methylphenyl)amino]anthraquinone

EC Number:

255-460-7

EC Name:

1,4-bis[(2-ethyl-6-methylphenyl)amino]anthraquinone

Cas Number:

41611-76-1

Molecular formula:

C32H30N2O2

IUPAC Name:

1,4-bis[(2-ethyl-6-methylphenyl)amino]-9,10-anthraquinone

Test material form:

solid

Details on test material:

Testing proposal: To be confirmed

Results and discussion

Transformation products:

no