N-cyclohexylbenzothiazole-2-sulfenamide

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study planned

Justification for type of information:

Testing proposal OECD 307 CBS
A simulation test is a standard requirement under REACH for substances in the tonnage band 100-1000 and >1000 to/a. CBS is not readily biodegradable and has a high adsorption behaviour expressed by a logKow of 5.02. Therefore, CBS could potentially fulfill the P/vP and B/vB criteria.

Selection of the relevant environmental compartment:
Relevant information can be taken from one member of the category (DCBS, CAS 4972-32-2) where investigations in soil exist.
1. In the substance evaluation for DCBS, soil was selected as the compartment of concern.
2. The resulting soil simulation study for DCBS according to OECD 307 resulted in long dissipation times leading to an evaluation of the substance as vP
Both substances have some similar behaviour in relevant physico-chemical properties: CBS has a high adsorption potential (logKow 5.02) but lower than DCBS (logKow 5.95. CBS hydrolyses rapidly with a DT50 of 13.4h at 20°C whereas DCBS hydrolyses less rapidly. It is concluded that information from DCBS can be used as a starting point for CBS.
A soil simulation test is also needed for a bioaccumulation study which has been proposed by the Registrant in case that CBS is P/vP. The high logKow of 5.02 indicates a high adsorption potential. However, the substance also hydrolyses with a half-life of 13.4 hours. For this situation concerning hydrolysable substances with high absorption behaviour, REACH Guidance R7c (p.29) (2017) states:
“The effect of hydrolysis may be a significant factor for substances discharged mainly to the aquatic environment: if the substance is sufficiently hydrophilic, its concentration in water may be reduced by hydrolysis so the extent of bioconcentration in aquatic organisms would also be reduced. However, for substances which are highly adsorptive to organic matter and/or lipids, the adsorption rate is, in most cases, faster than the hydrolysis rate. Therefore, hydrolysis rate should normally not intervene with assessment of bioaccumulation potential. In case a substance has a fast hydrolysis rate, the degradation potential of the substance in sediment and/or soil needs to be evaluated/tested first and if the substance is stable enough in sediment and/or soil from the perspective of quantitative risk assessment and/or PBT/vPvB assessment, the bioaccumulation potential of the substance itself needs to be evaluated/tested in conditions ensuring a stable exposure concentration despite fast hydrolysis.”
As a conclusion, a simulation study in soil is proposed from the following reasons
1. Soil is the “worst-case” compartment considering the lowest degradation potential
2. A simulation study in soil is needed for the prospected bioaccumulation study.



NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on which testing is proposed to be carried out
: N-Cyclohexylbenzothiazole-2-sulphenamide


CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION [please address all points below]:
- Grouping and read-across
: CBS is member of the category of the "sulphenamides"
- Substance-tailored exposure driven testing: 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:
- The substance is not readily biodegradable

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design / methodology proposed [if relevant]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).]

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Deviations:

not applicable

GLP compliance:

yes (incl. QA statement)

Test type:

laboratory

Test material

Test material information

Constituent 1

Reference substance name:

N-cyclohexylbenzothiazole-2-sulfenamide

EC Number:

202-411-2

EC Name:

N-cyclohexylbenzothiazole-2-sulfenamide

Cas Number:

95-33-0

Molecular formula:

C13H16N2S2

IUPAC Name:

N-(1,3-benzothiazol-2-ylsulfanyl)cyclohexanamine

Test material form:

solid

Details on test material:

Batch No. C190916VCZ

Radiolabelling:

yes