Thiodiglycol

Genetic toxicity: in vivo

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

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2001

Reference 2

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

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

Test material information

Constituent 1

Reference substance name:

Reference substance 001

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 or test system 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.