Isopropylnaphthalene

Endpoint summary

Additional information

• Genetic toxicity in vitro

Target substance (isopropylnaphthalene - isomeric mixture)

Two valid Ames tests (including special tester strains, TA 102 and E.coli, respectively) (OECD TG 471) and a valid chromosome aberration study (OECD TG 473) conducted with monoisopropyl naphthalene (MIPN isomer mixture) have been located:

Hamann/BSL 2002 (Ames test with target substance):

MIPN (isomeric mixture) caused a weak but not reproducible increase in gene mutations in the genome of the tester strain Salmonella typhimurium TA 100 in the presence of metabolic activation, however at cytotoxic concentrations, without a clear dose-response relationship.

METI 2006 (Ames test with target substance):

There was not any evidence of a mutagenic potential in an equivalent Ames-Test, which demonstrates the absence of a mutagenic potential of MIPN.

METI 2007 (CA test with the target substance):

This valid test using CHL fibroblast cells failed to reveal any clastogenic potential.

Supporting substance (bis(isolpropyl)naphthalene)

Three valid tests to assess the genotoxic potential of DIPN isomer mixture, the structure-analogue of MIPN, are used to read across to the target substance: One bacterial reverse mutation assay, one mammalian cell gene mutation assay and one in-vitro mammalian chromosome aberration test were performed according or similar to the respective OECD TG.

Grötsch/Leimbeck 1986 (Ames test):

In a bacterial reverse mutation assay using four strains of S. typhimurium, there was no evidence of an increase in revertant colonies above background in any strain and at any concentration tested with and without metabolic activation. DIPN proved to be negative in the Ames test under the test conditions used.

Ransome/Huntington 1999 (mammalian cell gene mutation (TK) assay):

The mutagenic potential of DIPN was tested in an in vitro mammalian cell gene mutation assay using mouse lymphoma L5178Y cells. There was no evidence of increases in mutant frequency according to the criteria of the test for all test substance concentrations tested without and with metabolic activation. It can be concluded that DIPN does not demonstrate mutagenic potential under the test conditions of this assay.

Brooker/Huntington 1988 (mammalian chromosomal aberration test):

In an in vitro mammalian chromosome aberration test, DIPN did not demonstrate any increase in chromosomal damage at any dose level either without or with metabolic activation. There was no evidence of any clastogenic activity under the conditions of the test used. 

• Genetic toxicity in vivo

The genotoxic potential of DIPN in vivo was investigated in one valid test.

Sterner/IBR 1986 (micronucleus assay):

Under the conditions of the micronucleus test performed, DIPN administered at 2 mL/kg bw did not lead to any significant increase in the frequency of micronucleated polychromatic erythrocytes compared to control values at any of the three time points examined.

Short description of key information:
MIPN isomer mixture [CAS no. 29253-36-9] exhibited neither mutagenic activity in two valid Ames tests [OECD 471] nor clastogenic activity in a valid cytogenetic assay using mammalian cell culture. For bis(isopropyl)naphthalene (DIPN), a closely structure-related substance, three different tests of in-vitro genetic toxicity (bacterial and mammalian cell mutation and chromosomal aberration) and one in-vivo micronucleus test did not provide any evidence of a genotoxic potential, thus underlining that MIPN is unlikely to harbour a significant genotoxic potential.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Overall, it is concluded that MIPN does not harbour a significant genotoxic potential. Therefore, no classification is required (see discussion above).