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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP status not known, near guideline study, published in peer reviewed literature, minor restrictions in design and/or reporting but otherwise adequate for assessment.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1981

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
TA102 was not included
Principles of method if other than guideline:
Plate incorporation protocol using Salmonella strains TA98, TA100, TA1535, TA1537 and TA 1538 in the absence or presence of liver S9 from male Wistar rats induced with Aroclor 1254.

GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
o-xylene
EC Number:
202-422-2
EC Name:
o-xylene
Cas Number:
95-47-6
Molecular formula:
C8H10
IUPAC Name:
o-xylene
Details on test material:
Obtained from J.T. Baker Chemicals (Deventer, The Netherlands).

Method

Species / strain
Species / strain / cell type:
S. typhimurium, other: TA1535, TA1537, TA1538, TA98, TA100
Metabolic activation:
with and without
Metabolic activation system:
Rat liver S9 (9000 g supernatant) prepared from male Wistar rats either untreated or pretreated with Aroclor 1254.
Test concentrations with justification for top dose:
20, 50, 100, 200 or 500 µg/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: see below
Details on test system and experimental conditions:
Each test was done in triplicate. Plates were counted after 48 h incubation at 37°C with a Biotran II automated colony counter.
Positive control substances:
benzo(a)pyrene (7.5 µg/plate), 2-Aminoanthracene (1 µg/plate) and 9,10-Dimethylbenzanthracene (20 µg/plate) were tested with activation by liver S9 mix derived from either untreated or Aroclor 1254-treated rats.
sodium azide (5 µg/plate), 4-nitroquinoline-1-oxide (2 µg/plate), 4-nitro-o-phenylenediamine (10 µg/plate) and 9-aminoacridine (200 µg/plate) were tested without activation.

Results and discussion

Test results
Species / strain:
S. typhimurium, other: TA98, TA100, TA1535, TA1537, TA1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: 80-100% of the bacteria at the highest dose survived
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested

Applicant's summary and conclusion

Conclusions:
Interpretation of results:
negative

o-xylene was not mutagenic in the Ames test
Executive summary:

o-xylene was not mutagenic when tested in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537 and TA1538 with and without activation by S9 mix from livers of Aroclor 1254 treated rats at concentrations up to 500 µg/plate, using a plate incorporation assay.