Pentyl 2-cyano-(3-(6-methoxybenzothiazol-2-ylimino)-2,3-dihydro-1H-isoindol-1-ylidene)acetate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: gene mutation

Type of information:

experimental study planned

Justification for type of information:

TESTING PROPOSAL ON VERTEBRATE ANIMALS
NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on which testing is proposed to be carried out: FC 84508 PK
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 in vivo studies are available to adequately address this endpoint.
- Available non-GLP studies: no in vivo studies are available to adequately address this endpoint.
- Historical human/control data: There is no historical human data available for this substance on ‘genetic toxicity in vivo’. Hence no evidence of human adverse effect.
- (Q)SAR: (Q)SARs are not considered adequate to address this endpoint.
- In vitro methods: In-vitro studies were already presented, but in vivo data are requested according to ECHA guidance documents. Presented data included a positive result in one strain in a study conducted according to OECD Guideline 471 (Bacterial reverse mutation assay), a negative study according to OECD Guideline 473 (In vitro mammalian chromosome aberration test) and a negative study according to OECD Guideline 476 (In vitro mammalian cell gene mutation assay)
- Weight of evidence: in absence of additional data no WoE can be done.
- Grouping and read-across: no analogues were identified with data on genotoxicity that were considered relevant to read across.
- 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 ECHA guidance R.7a states that following a positive result in an in vitro test, “adequately conducted somatic cell in vivo testing is required to ascertain if this potential can be expressed in vivo.”
Although the in-vitro mutagenicity assay in mammalian cells and the in-vitro chromosome aberration assay in mammalian cells are negative, it cannot be sufficiently deduced from these test results that the positive effect in S. typhimurium TA 98 is not relevant for in vivo situations.
FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design: According to OECD 489 in liver, glandular stomach and duodenum of one sex only, as no toxicologically relevant differences were observed between males and females.
No germ cells will be collected, as the assay is not validated for germ cells, the TG states "this guideline is not considered appropriate to measure DNA strand breaks in mature germ cells. Since high and variable background levels in DNA damage were reported in a literature review on the use of the comet assay for germ cell genotoxicity".
Furthermore, no adverse effects have been noted in the subacute toxicity study and the reproductive/developmental screening study.

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 489 (In vivo Mammalian Alkaline Comet Assay)

GLP compliance:

yes

Type of assay:

mammalian comet assay

Test material

Test material information

Constituent 1

Test material form:

solid: particulate/powder

Test animals

Species:

rat

Sex:

male

Administration / exposure

Route of administration:

oral: gavage

Duration of treatment / exposure:

2 treatments (24 h and 4 h prior to preparation)

Frequency of treatment:

2 treatments

Post exposure period:

24 h and 4 h

No. of animals per sex per dose:

6 (one sex, as there is no gender difference)

Control animals:

yes, concurrent vehicle

Positive control(s):

yes

Examinations

Tissues and cell types examined:

A) Analysis of hepatocytes
Isolation of hepatocytes by mincing
Determination of dead cells in 500 cells per slide (1500 per animal)
Performance of the alkaline comet assay
Analysis of 50 cells per slide (150 cells per animal)
B) Analysis of cells from the stomach
Isolation of cells from the stomach by scraping
Determination of dead cells in 500 cells per slide (1500 per animal)
Performance of the alkaline comet assay
Analysis of 50 cells per slide (150 cells per animal)
C) Analysis of cells from small intestine
Isolation of cell nuclei from the small intestine by mincing
Determination of dead cells in 500 cells per slide (1500 per animal)
Performance of the alkaline comet assay
Analysis of 50 cells per slide (150 cells per animal)