2,2,2-trichloroethane-1,1-diol

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Dosing for 3 days, with further 1 day before examination

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

Use of standard methods recommended by OECD
Data performed as part of US National Toxicity Programme in the period up to publication in 1996
The study was performed twice.

Data source

Reference

Reference Type:

review article or handbook

Title:

Unnamed

Year:

1996

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

GLP compliance:

not specified

Remarks:

Data source claims GLP compliance, but no evidence provided by publisher of the data

Type of assay:

mammalian erythrocyte micronucleus test

Test material

Test material information

Constituent 1

Reference substance name:

2,2,2-trichloroethane-1,1-diol

EC Number:

206-117-5

EC Name:

2,2,2-trichloroethane-1,1-diol

Cas Number:

302-17-0

Molecular formula:

C2H3Cl3O2

IUPAC Name:

2,2,2-trichloroethane-1,1-diol

Test material form:

solid: granular

Specific details on test material used for the study:

Referred to as chloral hydrate

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

Phosphate buffered saline

Details on exposure:

Three injections, once a day for three days
Cells were harvested 24 hours after third injection.

Duration of treatment / exposure:

3 days

Frequency of treatment:

Daily

Post exposure period:

24 hours

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

Control
Injected with 0.4 mL of phosphate-buffered saline only

Doses / concentrations 2

Dose / conc.:

125 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

250 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

500 mg/kg bw/day (nominal)

No. of animals per sex per dose:

5 mice per treatment per replicate
Study replicated, making total 10 mice per group (noting only 4 were used for evaluation in one negative control and one positive control)

Control animals:

yes, concurrent vehicle

other: Positive: cyclophosphamide

Positive control(s):

Cyclophosphamide

Examinations

Tissues and cell types examined:

Bone marrow cells (polychromatic erythrocyte, PCE)

Details of tissue and slide preparation:

Blood smears were prepared from bone marrow cells obtained from the femurs.
Air-dried smears were fixed and stained; 2,000 polychromatic erythrocytes (PCEs) were scored for the frequency of micronucleated
cells in each of four or five animals per dose group.

Statistics:

Significance of micronucleated PCEs/1,000 cells PCEs was evaluated by the one-tailed trend test (ILS, 1990); significant at P#0.025

Results and discussion

Test results

Test results 1

Key result

Sex:

male

Genotoxicity:

ambiguous

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

Key result

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

The test was repeated.
Both assays resulted in slight increase in micronucleated PCEs, with the first assay just significant following statistical analysis. The second assay was negative by statistical analysis.

Any other information on results incl. tables

Male mice injected with 125 to 500 mg/kg showed a slight dose-related trend in the frequency of micronucleated erythrocytes in bone marrow sampled 24 hours after treatment

* considered significant

Dose level	No. Mice each assay	No. micronucleated PCEs  First assay	No. micronucleated PCEs  Second assay
Phosphate buffer control	4 + 5	2.9 ± 0.5	1.7 ± 0.3
Positive control	4 + 5	19.1 ± 2.2	17.4 ± 1.7
125 mg/kg	5 + 5	2.1 ± 0.5	2.2 ± 0.5
250 mg/kg	5 + 5	2.7 ± 0.6	2.1 ± 0.3
500 mg/kg	5 + 5	4.4 ± 0.8*	3.5 ± 0.5

Applicant's summary and conclusion

Conclusions:

Male mice injected with 125 to 500 mg/kg showed a slight, but statistically signigicant dose-related trend in the frequency of micronucleated erythrocytes in bone marrow sampled 24 hours after treatment in one assay, but negative in a repeated test.

Executive summary:

The US National Toxicity Programme report concludes that mouse liver microsomes generate free radical intermediates that resulted in endogenous lipid peroxidation, forming malondialdehyde, formaldehyde, acetaldehyde, acetone, and propionaldehyde. Induction of endogenous lipid peroxidation by xenobiotics through generation of free radical species results in alterations of cellular function and genotoxic damage. It is considered by the authors likely that metabolisms of chloral hydrate following high levels of repeated exposure may lead to potentially mutagenic metabolites being formed.