reaction mass of ethylbenzene and m-xylene and p-xylene

Genetic toxicity: in vitro

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

Test material information

Constituent 1

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 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1538

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

Test results 1

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: 80-100% of the bacteria survived at 500 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: 80-100% of the bacteria survived at 500 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: 80-100% of the bacteria survived at 500 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 4

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: 80-100% of the bacteria survived at 500 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 5

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: 80-100% of the bacteria survived at 500 μg/plate

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.