Ethane, 1,1,2-trichloro-1,2-difluoro-

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: DNA damage and/or repair

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

The data source is the competent authority and it is considered reliable. Although not all the details on materials and results are provided, the test method is similar to official guideline methods.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

no positive control included

GLP compliance:

not specified

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

1,1,2-trichloro-1,2-difluoroethane

EC Number:

940-543-9

Cas Number:

354-15-4

Molecular formula:

C2HCl3F2

IUPAC Name:

1,1,2-trichloro-1,2-difluoroethane

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): R122a

Test animals

Species:

mouse

Strain:

not specified

Sex:

not specified

Administration / exposure

Route of administration:

oral: unspecified

Vehicle:

no data

Duration of treatment / exposure:

2 single administrations.

Frequency of treatment:

Twice with the intervals of 24 hours.

Post exposure period:

24 hours

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

780 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

3 900 mg/kg bw/day

No. of animals per sex per dose:

7

Control animals:

yes

Examinations

Tissues and cell types examined:

Erythrocytes of femoral bone marrow.

Results and discussion

Test results

Key result

Sex:

not specified

Genotoxicity:

negative

Toxicity:

not examined

Negative controls validity:

valid

Positive controls validity:

not examined

Any other information on results incl. tables

Summary of Results

Studied dose	Number of animals	Polychromatocytes
		Polychromatocytes analysed	Polychromatocytes with micronuclei Mav. ± M	% tst
Control	7	7,000	0.31±0.019
780 mg/kg	7	7,000	0.37±0.042	1.3
3,900 mg/kg	7	7,000	0.42±0.051	2.02

Applicant's summary and conclusion

Conclusions:

Under the test conditions of the reported study, HCFC 122a did not show mutagenic activity following oral administration to mice.

Executive summary:

The objective of the study was the assessment both of the reprotoxicity potential and of the genotoxicity potential of HCFC 122a. To this scope, an in vivo micronucleus test and an Ames test were performed.

 

The micronucleus test was conducted on white mice weighing 18-20 g.

HCFC 122a was administered to mice twice with the intervals of 24 hours, at doses of 1/2 and 1/10 of the LD50 = 7800 mg/Kg. The animals were sacrificed in 24 hours after the last administration.

Femoral bones were taken and the bone marrow was placed into a drop of group IV human serum inactivated at 56 °C for 2 hours and took a smear. After drying of preparations in air, the smear was consequently stained with Main-Grunwald and Giemsa stains.

Analysis of bone marrow smear was performed using the immersion microscope objective Jenaval (magnification H/100x12.5¥0.17-A). Preparations with well expanded erythrocytes, the surface of which did not have protuberances and folds were considered suitable for the analysis. 1000 polychromatocytes were counted per each animal.

HCFC 122a mutagenicity was assessed by the presence or absence of difference in the number of micronuclei between the experimental and control animals. Data are shown as a number of polychromatocytes containing micronuclei in percent. For the statistical evaluation, the original data for each animal were standardized according to the formula:

 

W = arc sin [(r+0.375)/(n+0.75)] 1/2

where r – number polychromatophils with micronuclei

           n – the total number of polychromatocytes,

and then used t_st– Student’s t test.

 

The data obtained indicate that the incidence of micronuclei in the bone marrow cells of experimental mice for the studied doses was not statistically different from the control values.

Thus, the studied dosage range of HCFC 122a upon oral administration to mice in micronucleus test did not have mutagenic activity.