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Diss Factsheets

Toxicological information

Genetic toxicity: in vivo

Currently viewing:

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
experimental study
Adequacy of study:
key study
Study period:
not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Near guideline study, GLP status unknown, published in peer reviewed literature, minor restrictions in design and/or reporting but otherwise adequate for assessment.
Justification for type of information:
N/A

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1985

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
yes
Remarks:
only one sex tested
Principles of method if other than guideline:
not specified
GLP compliance:
not specified
Type of assay:
micronucleus 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:
- Name of test material (as cited in study report): o-dimethylbenzene (o-xylene)
- Supplier: Merck Co., D-8011 Hohenbrunn, Germany
- Purity: 98.0%
Specific details on test material used for the study:
not specified

Test animals

Species:
mouse
Strain:
NMRI
Details on species / strain selection:
not specified
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: NMRI mice obtained from Zentralinstitut fur Versuchtstiere, D-3000 Hannover, Germany.
- Weight at study initiation: 25-30 g
- Housing: 5/cage
- Diet: Laboratory Purina chow ad libitum
- Water: ad libitum
ENVIRONMENTAL CONDITIONS: no details reported

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
- Vehicle(s)/solvent(s) used: corn oil (when doses were too small to be injected)
Details on exposure:
not specified
Duration of treatment / exposure:
2 injections, 24 h apart
Frequency of treatment:
2 ip injections 24 hours apart
Post exposure period:
6 hours after 2nd injection
Doses / concentrationsopen allclose all
Dose / conc.:
0.12 other: mL/kg (nominal)
Remarks:
106 mg/kg, 2 injections
Dose / conc.:
0.25 other: mL/kg (nominal)
Remarks:
220 mg/kg, 2 injections
Dose / conc.:
0.37 other: mL/kg (nominal)
Remarks:
320 mg/kg, 2 injections
Dose / conc.:
0.5 other: mL/kg (nominal)
Remarks:
440 mg/kg, 2 injections
No. of animals per sex per dose:
5 (test groups), 5 (positive control groups), 10 (negative/vehicle control group)
Control animals:
yes, concurrent vehicle
Positive control(s):
benzene, cyclophosphamide; 4-nitroquinoline 1-oxide
- Route of administration: ip injection
- Doses / concentrations: benzene 2 x 0.15, 0.30 and 0.60 mL/kg; cyclophosphamide 2 x 0.05 and 0.25 mL/kg; 4-nitroquinoline 1-oxide 2 x 0.12, 0.25 and 0.50 mL/kg

Examinations

Tissues and cell types examined:
polychromatic erythrocytes
Details of tissue and slide preparation:
6 hr after 2nd injection, animals were killed and bone marrow aspirated from both femurs and suspended in serum. After centrifugation, the cells in the sediment were used to prepare smears (2/femur) which were fixed and stained. All smears were coded, and examined under high magnification without knowledge of treatment and doses. 1000 PCEs/smear were screened for the presence of micronuclei.
Evaluation criteria:
not specified
Statistics:
Students t-test



Results and discussion

Test results
Key result
Sex:
male
Genotoxicity:
negative
Toxicity:
not specified
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
N/A

Any other information on results incl. tables

Effects of o-xylene on frequency of micronucleated polychromatic erythrocytes of femoral bone marrow of male NMRI mice

(based on Mohtashamipur E et al 1985, Arch Toxicol 58: 106-109, Table 2)

Substance

Dose

(mL/kg body weight)

Micronuclei/1000 PCEs

corn oil (vehicle control)

2 x 0.50

1.91± 1.037

o-xylene

2 x 0.12

1.80 ± 0.748

 

2 x 0.25

1.60 ± 0.663

 

2 x 0.37

1.70 ± 0.781

 

2 x 0.50

1.80 ± 0.748

4-nitroquinolin-1-oxide (positive control)

2 x 0.12

6.25 ± 0.829*

 

2 x 0.25

15.66 ± 4.784*

 

2 x 0.50

18.00 ± 2.160*

cyclophosphamide (positive control)

2 x 0.05

7.20 ± 1.077*

 

2 x 0.25

21.10 ± 4.346*

benzene (positive control)

2 x 0.15

4.40 ± 0.916*

 

2 x 0.30

8.40 ± 3.903*

 

2 x 0.60

12.90 ± 5.521*

* Significant (P<0.01)

Applicant's summary and conclusion

Conclusions:
Interpretation of results: negative
o-xylene does not induce micronuclei in bone marrow polychromatic erythrocytes of mice and is not therefore genotoxic.
Executive summary:

o-xylene does not induce micronuclei in bone marrow polychromatic erythrocytes of mice and is not therefore genotoxic.