Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions. Restrictions: no details about the purity of the TS.

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
2001
Reference Type:
publication
Title:
Toxicity Assessment of Thiodiglycol
Author:
Reddy G, Major MA, Leach GJ
Year:
2005
Bibliographic source:
International Journal of Toxicology, 24:435–442

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
Principles of method if other than guideline:
adopted 1997
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Lot No. 05701EQ, further data available from the sponsor

Test animals

Species:
mouse
Strain:
ICR
Sex:
male
Details on test animals and environmental conditions:
- Strain: Crl:CD-1(ICR) BR
- obtained from Charles River Lab, Raleigh (North Carolina) (preliminary study) or St. Constant (Quebec) (main study)
- at least 6 days acclimatization period
- randomization of animals
- at start of treatment period in the main study males ca. 8 weeks old, bw range 30.0-34.5 g; in the preliminary study males and females ca. 8 weeks old, bw range
30.2-34.8 g and 22.8-25.4 g, respectively

HOUSING and DIET
- animals housed in dose groups; polycarbonate cages used with hardwood chip laboratory bedding.
- temperature 18-26°C; 30-70% relative humidity; light/dark cycle 12h/12h; ventilation at least 10 air changes per h;
- certified rodent diet #5002 and tap water ad libitum; no contaminants in diet, water and wood chips (analysed)

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
sterile deionized water
Details on exposure:
- Formulation procedure (main study)
Test substance (TS) dissolved in the vehicle (sterile deionized water) immediatly before use; concentrations of 0, 50, 100, 200 mg/ml TS or 8 mg/ml cyclophosphamide (positive control); administration volume 10 ml/kg bw in all groups.
Duration of treatment / exposure:
Single exposure
Frequency of treatment:
Once
Post exposure period:
24 and 48 h
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 500, 1000, 2000 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
6 males in the main study
Control animals:
yes, concurrent vehicle
Positive control(s):
gavaged once with 80 mg/kg bw cyclophosphamide

Examinations

Tissues and cell types examined:
Bone marrow smears prepared (air dried, fixed with methanol)
Details of tissue and slide preparation:
Slides stained with May-Grünwald followed by Giemsa staining) for microscopic examination. Evaluation of slides on a blind basis; for each mouse, the number of micronucleated polychromatic erythrocytes (MPE) counted in 2000 polychromatic erythrocytes (PE); the ratio of PE versus normochromatic erythrocytes (NE) determined by scoring 500 erythrocytes per mouse; historical background frequency of micronuclei in this strain at this lab is 0.0 to 0.4%.
Evaluation criteria:
A statistical significant increase in the frequency of MPE must be demonstrated for at least one dose level, and a statistically significant dose-related response; historical data and other considerations of biological relevance were taken into account.
Statistics:
Data analysed by using an analysis of variance (Winer, 1971) on untransformed proportions of cells with micronuclei per mouse and on untransformed PE:NE ratios when the variances were homogeneous; ranked proportions used for heterogeneous variances; differences from control analysed by Dunnett's t-test; parametric and nonparametric tests used for trend analysis.

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
- Preliminary toxicity test
no clinical signs at any dose level; 2000 mg/kg bw used for the main study

- Clinical signs in the main study
no clinical signs observed in any group
- Cytogenetic in the main study
no significant differences in MPE values between vehicle controls and TS treated males of all dose groups; the PN/NE ratio was also not significantly altered in any TS treatment group; valid positive and negative control (also in comparison with historical data)

Any other information on results incl. tables

Cytogenetic summary table
Dose in mg/kg bw % MPE (SE) PE/NE ratio (SE)
and harvest time
vehicle 24 h 0.13 (0.02) 0.91 (0.03)
vehicle 48 h 0.09 (0.01) 0.84 (0.06)
500 24 h 0.09 (0.03) 0.79 (0.03)
1000 24 h 0.12 (0.03) 0.79 (0.04)
2000 24 h 0.11 (0.02) 0.82 (0.05)
2000 48 h 0.10 (0.02) 0.91 (0.04)
positive
control 24 h 3.07 (0.35)** 0.67 (0.04)*

SE: standard error; *: p<0.05; **: p<0.01

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
No mutagenic activity in the mouse bone marrow micronucleus test at dose levels up to 2000 mg/kg bw.
Executive summary:

Guideline study with acceptable restrictions (no details about the test substance).

In the mouse bone marrow micronucleus assay 6 male mice per dose were gavagaed once with 0, 500, 1000, or 2000 mg/kg and bone marrow prepared for evaluation 24 and 48 h after application. No increase in the frequency of micronuclei was detected. No clinical toxicity or cytotoxic effects on the bone marrow were found even at 2000 mg/kg bw, the highest test dose recommended by the current guideline. The positive controls were valid.

Conclusion: No mutagenic activity in the mouse bone marrow micronucleus test at dose levels up to 2000 mg/kg bw.