1-imino-1H-isoindol-3-amine

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian cell study: DNA damage and/or repair

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: 1-imino-1H-isoindol-3-amine (Ingrain Blue 2.2)

CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- Available GLP studies - in vitro methods:
1) Bacterial reverse mutation assay (Ames) according to OECD 471: The outcome of this study was negative, i.e. the test substance is not mutagenic towards bacteria. The study was valid and reliable without restrictions and does not trigger additional testing.
2) Micronucleus study according to OECD 487: The outcome of this study is negative, i.e. the test item did not show clastogenic and/or aneugenic activity. The study was valid and reliable without restrictions and does not trigger additional testing.
3) Mammalian cell gene mutation study, using thymidine kinase gene (mouse lymphoma) according to OECD 490: The result of this study is positive, i.e. clastogenic effects were induced by the test item.
- Weight of evidence: Since at least one positive result was observed, further in vivo testing is needed.
- Available non-GLP studies: not available
- Historical human data: not available
- (Q)SAR: not available
- Grouping and read-across: no read-across candidates identified.
- 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:
All possible adaptation possibilities were considered and none were applicable. Exposure-based waiving could also not be used.

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design / methodology proposed:
To gain further insight on the genetic toxicity potential of the test item, we propose to perform an in vivo comet assay (OECD TG 489) on intestinal cells which is an indicator test for DNA lesions. According to Column 2 of Annex VIII, appropriate in vivo mutagenicity studies shall be considered in case of a positive result in any of the genotoxicity studies in Annex VII or VIII. According to the Guidance on Information requirements, Chapter 7.a (2017) for indications of clastogenicity, a micronucleus test, a chromosome aberration test or a Comet assay would be the appropriate follow up test; whereas for indications of gene mutations, a transgenic rodent gene mutation assay, a Comet assay, or in some cases an unscheduled DNA synthesis test. In this case, an in vivo Comet assay is justified according to the Guidance.

The liver is the standard organ of the Comet assay, but if the substance is not absorbed, the liver will not be reached. Therefore it is proposed to add gastro-intestinal tissue as target organ. The stomach is usually first site of contact for substances after oral exposure, although other areas of the gastro- intestinal tract such as the duodenum and jejunum can also be considered as site-of-contact tissues and may be considered more relevant for humans than the rodent glandular stomach. Care should be taken to ensure that such tissues are not exposed to excessively high test substance concentrations, but rather to expected exposure concentrations to avoid false positive reactions (Donovan & Burlinson, 2013). In the case of 1-imino-1H-isoindol-3-amine, the irritation potential should be taken into account for selection of the duodenum or jenunum as target tissues. The substance is classified for Skin irrit. 2 and Eye dam. 1. Cytoxicity in the rat stomach is likely, which may lead to equivocal or false positive reactions if stomach will be evaluated. To avoid these equivoval or false positive reactions, it is considered more appropriate to use the duodenum or jejunum (depending on the experience of the selected Laboratory) as a representative site of first contact but also here dose selection should be carefully done to avoid lesions.

Reference:
Donovan MO & Burlinson B. Maximum dose levels for the rodent comet assay to examine damage at the site of contact or to the gastrointestinal tract. Mutagenesis vol. 28 no. 6 pp. 621–623, Advance Access publication 3 October 2013;

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 489 (In vivo Mammalian Alkaline Comet Assay)

Deviations:

yes

Remarks:

with liver and small intestine (duodenum or jejunum, depending on experience of lab) as target tissues.

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian comet assay

Test material

Test material information

Constituent 1

Reference substance name:

1-imino-1H-isoindol-3-amine

EC Number:

222-426-8

EC Name:

1-imino-1H-isoindol-3-amine

Cas Number:

3468-11-9

Molecular formula:

C8H7N3

IUPAC Name:

1-imino-1H-isoindol-3-amine

Test material form:

solid: particulate/powder