1,1,1-trifluoroethane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

The substance did not demonstrate mutagenic potential in a reliable in vitro cell mutation assay in the presence or absence of a metabolic activation system. The substance was negative (ie non genotoxic), in two reliable in vitro bacterial gene mutation assays. A positive result was reported in a third bacterial assay however this study is considered unreliable. It was also negative in a reliable in vitro cytogenetics assay.

A structurally related substance (1,1,1,2-tetrafluoroethane) gave a negative result in a reliable in vitro mammalian cell gene mutation assay.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro transformation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 June 2018 - 24 July 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 490 (In Vitro Mammalian Cell Gene Mutation Tests Using the Thymidine Kinase Gene)

Version / remarks:

29 July 2016

GLP compliance:

yes

Type of assay:

in vitro mammalian cell gene mutation tests using the thymidine kinase gene

Species / strain / cell type:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Metabolic activation system:

S9 fraction, prepared from male Sprague-Dawley derived rats, dosed with phenobarbital and 5,6-benzoflavone to stimulate mixed-function oxidases in the liver was stored at -90 to -70°C.

Test concentrations with justification for top dose:

The highest concentration selected (70% v/v) was the maximum achievable concentration in the test system without detrimental effects on the cell culture.

Vehicle / solvent:

Sterile air

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

methylmethanesulfonate

Details on test system and experimental conditions:

L5178Y mouse lymphoma (3.7.2c) cells heterozygous at the thymidine kinase locus, TK +/- were used. Spontaneous thymidine kinase deficient mutants, TK -/-, were eliminated from the cultures by a 24-hour incubation in the presence of methotrexate, thymidine, hypoxanthine and glycine two days prior to storage at -196 to -150°C, in heatinactivated donor horse serum (HiDHS) containing 10% DMSO. Cultures were used within ten days of recovery from frozen stock. Cell stocks are periodically checked for freedom from mycoplasma contamination.

The following media were used:
R0 RPMI 1640, buffered with 2 mg/mL sodium bicarbonate, supplemented with 2.0 mM L-glutamine and 50 ug/mL gentamicin.
R10p R0, supplemented with 0.1% v/v Synperonic F68, 1.0 mM sodium pyruvate and HiDHS at 10% v/v.
R10p medium was used for cell culture unless otherwise specified.
Selective medium consisted of R10p containing 4 ug/mL trifluorothymidine (TFT).

Positive Controls
In the absence of S9 mix, Methyl methanesulphonate (MMS) in DMSO at concentration of 10 ug/mL (3-hour exposure).
In the presence of S9 mix, Benzo[a]pyrene (BaP) in DMSO at concentration of 1.5 ug/mL (3-hour exposure).

S9 Metabolizing System
S9 fraction, prepared from male Sprague-Dawley derived rats, dosed with phenobarbital and 5,6-benzoflavone to stimulate mixed-function oxidases in the liver and stored at -90 to -70°C. S9 fraction (5% v/v), glucose-6-phosphate (6.9 mM), NADP (1.4 mM) in R0 was used. The co-factors were prepared, neutralised with 1N NaOH and filter sterilised before use.

The highest concentration selected (70% v/v) was the maximum achievable concentration in the test system without detrimental effects on the cell culture. Concentrations within the range of 5 to 30% was avoided due to the known lower and upper flammability levels of the test item, 7 and 19% respectively.
All concentrations cited in this report are expressed in terms of pure HFC-143a as received.

The final nominal concentrations to which cells were exposed initially are given below:
Preliminary toxicity test:: 1, 5, 30, 40, 50, 60 and 70% v/v
Mutation tests:
-S9 mix (3 hours) 30, 40, 50, 60 and 70% v/v
+S9 mix (3 hours) 30, 40, 50, 60 and 70% v/v (also assessed for determination of the mutant phenotype)
Additional Mutationtests:
-S9 mix (3 hours) 22.3*, 40, 50, 60 and 70% v/v (also assessed for determination of the mutant phenotype)
* Actual concentration

Osmolality and pH
The effects of HFC-143a on the osmolality and pH of the culture medium were measured by analyzing samples of R10p media treated with either the vehicle (sterile air) or test item at 70% v/v. Precipitate was assessed by eye at the end of the exposure period in treated R10p media-only cultures as part of the preliminary toxicity test.


Preliminary Toxicity Test Procedure: Cells were exposed to the substance for 3 hours in the absence and presence of S9 mix. For 3-hour exposures, cultures contained a total of 1.2 x 10^7 cells. The final volume of the cultures was 10 mL and the final concentration of the S9 fraction was 2% v/v. One culture was prepared for each concentration of the substance for each test condition. Vehicle controls were tested in duplicate for each test condition.

Mutation Test Procedure: 3-hour Treatment in the Absence and Presence of S9 Mix. The procedure for preparing the cell suspension was the same as for the preliminary toxicity test. Cultures contained a total of 1.2 x 10^7 cells in a final volume of 10 mL. The final concentration of the S9 fraction was 2% v/v. Duplicate cultures were prepared throughout for each concentration of substance and positive control. Quadruplicate cultures were prepared for vehicle controls. Aliquots of 100 µL of positive control were added to the relevant cultures, and then all cultures were incubated, for 3 hours at 34 to 39°C. Five dilutions of the substance were tested.

Evaluation criteria:

Acceptance criteria for substance:
The highest concentration tested was one that allowed the maximum exposure up to 70% v/v for freely soluble compounds, or the limit of toxicity (i.e. relative total growth reduced to approximately 10 to 20% of the concurrent vehicle control) or the limit of solubility. For a toxic substance, at least 4 analysable concentrations should have been achieved which ideally spanned the toxicity range of 100 to 10% RTG.

Acceptance criteria for vehicle controls:
The mean vehicle control value for mutant frequency was between 50 to 170 x 10^-6.
The mean cloning efficiency was between 65 to 120%.
The mean suspension growth was between 8 to 32 on Day 2 following 3-hour treatments.

Obvious outliers were excluded. However, there were at least 2 vehicle control cultures remaining.

Acceptance criteria for positive controls:
Positive controls showed an absolute increase in mean total MF above the mean concurrent vehicle control MF of at least 300 x 10^-6. At least 40% of this was due to the number of small mutant colonies.
Mean RTG’s for the positive controls were greater than 10%.
There was an absence of confounding technical problems such as contamination, excessive numbers of outliers and excessive toxicity.

Criteria for Assessing Mutagenic Potential
The following criteria were applied for assessment of individual assay results using data for MF where the RTG normally exceeded 10%:
Definitions: GEF = Global Evaluation Factor. For microwell assays this is 126 x 10-6.
Providing that all acceptability criteria were fulfilled, the test item was considered to be clearly positive if, in any of the experimental conditions examined the increase in MF above the concurrent background exceeded the GEF and the increase was concentration related (i.e., there is a significant positive linear trend). The test item is then considered able to induce mutation in this test system.

Statistics:

The data were analysed using Fluctuation application SAFEStat (SAS statistical applications for end users). Statistics were only reported if the sum of the mean concurrent vehicle control mutant frequency and the Global Evaluation Factor was exceeded, and this was accompanied by a significant positive linear trend (p<0.05).

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

The osmolality and pH of the substance in medium were measured by analysing samples of R10p media, dosed with either the vehicle (sterile air) or a substance formulation at 70% v/v. For medium dosed with substance at 70% v/v; no fluctuations in osmolality of the medium of more than 50 mOsmol/kg and no fluctuations in pH of more than 1.0 unit were observed compared with the vehicle control. The maximum final concentration tested in the preliminary toxicity test was 70% v/v as this is the maximum achievable concentration in the test system without detrimental effects on the cell culture.

Preliminary Toxicity Test:
No precipitate (observed by eye at the end of treatment) was observed at concentrations of 70% v/v in the absence and presence of S9 mix, respectively, following a 3-hour exposure. Exposure to the substance at concentrations from 1 to 70% v/v in the absence and presence of S9 mix resulted in no reduction in the relative suspension growth (RSG) values. Concentrations used in the main test were based upon these data.

Main Mutation Test - 3-hour Treatment in the Absence of S9 Mix:
Cultures were exposed to the substance at concentrations from 25.2 to 45.7% v/v. No precipitate was observed by eye at the end of treatment. The results of the achieved concentration analysis showed that the highest concentration was -34.7% from the nominal concentration of 70% v/v, this was considered to be unacceptable. The test was therefore terminated and an additional test was performed.

Additional main Mutation Test - 3-hour Treatment in the Absence of S9 Mix:
Cultures were exposed to the substance at concentrations from 22.3 to 70% v/v. No precipitate was observed by eye at the end of treatment. Cultures exposed to the substance at concentrations from 22.3 to 70% v/v were assessed for determination of mutation frequency. Mean relative total growth (RTG) values from 84 to 65% were obtained relative to the vehicle control. There were no increases in the mean mutant frequencies of any of the test concentrations assessed that exceeded the sum of the mean concurrent vehicle control mutant frequency and the Global Evaluation Factor (GEF), within acceptable levels of toxicity.

The positive control, methyl methanesulphonate, induced an acceptable increase in mutation frequency and an acceptable increase in the number of small colony mutants.

Main Mutation Test - 3-hour Treatment in the Presence of S9 Mix:
Cultures were exposed to the substance at concentrations from 30 to 70% v/v. No precipitate was observed by eye at the end of treatment. Cultures exposed to the substance at concentrations from 30 to 70% v/v were assessed for determination of mutation frequency. Mean RTG values from 107 to 92% were obtained relative to the vehicle control. There were no increases in the mean mutant frequencies of any of the test concentrations assessed that exceeded the sum of the mean concurrent vehicle control mutant frequency and the GEF, within acceptable levels of toxicity.

The positive control, benzo[a]pyrene, induced an acceptable increase in mutation frequency and an acceptable increase in the number of small colony mutants.

Formulation Analysis:
The results of formulation analysis showed that the achieved concentrations of HFC-143a were within the target range 100% +/- 20%, with the exception of the highest concentration in the main test –S9 mix, and the lowest concentration in the additional main test –S9 mix, which were -34.7% and -25.7%, respectively.

Remarks on result:

other: No mutagenic potential.

Remarks:

Negative study.

Table 1: Preliminary toxicity test, relative suspension growth

i) In the absence of S9 mix – 3-hour exposure

Treatment / Nominal concentration (% v/v)	Replicate ID	Cell concentration (x10^5/mL) 24h/48h	Suspension Growth Day 2	Relative Suspension Growth (%)
Vehicle Control*	A B	4.37/12.17 5.24/10.53	13.30 13.80	100
HFC-143a (1)	A	4.80/10.72	12.87	95
HFC-143a (5)	A	4.55/11.34	12.90	95
HFC-143a (30)	A	5.28/9.87	13.04	96
HFC-143a (40)	A	5.92/9.31	13.79	102
HFC-143a (50)	A	4.69/10.50	12.30	91
HFC-143a (60)	A	4.81/10.25	12.32	91
HFC-143a (70)	A	5.14/9.97	12.81	95
*Vehicle control = Sterile air

ii) In the presence of S9 mix – 3-hour exposure

Treatment / Nominal concentration (% v/v)	Replicate ID	Cell concentration (x10^5/mL) 24h/48h	Suspension Growth Day 2	Relative Suspension Growth (%)
Vehicle Control*	A B	5.98/11.14 5.80/10.80	16.64 15.65	100
HFC-143a (1)	A	6.12/10.91	16.68	103
HFC-143a (5)	A	6.28/11.07	17.36	108
HFC-143a (30)	A	6.10/10.89	16.60	103
HFC-143a (40)	A	5.87/11.59	17.01	105
HFC-143a (50)	A	6.26/11.15	17.46	108
HFC-143a (60)	A	5.85/11.68	17.09	106
HFC-143a (70)	A	5.92/11.49	17.01	105
*Vehicle control = Sterile air

Table 2: Additional main mutation test – 3-hour treatment in the absence of S9 mix, relative total growth

Treatment / Nominal concentration (% v/v)	Replicate ID	Cell concentration (x10^5/mL) 24h/48h	Mean Suspension Growth	Viability Plate Count* Day 2	Mean Cloning Efficiency (%)	RTG (%)	Mean RTG (%)
Vehicle Control**	A B C D	4.39/12.85 4.91/11.88 5.18/14.55 4.63/11.43	15.19	47 (192) 32 (192) 33 (192) 38 (192)	102	100	100
HFC-143a (22.3#)	A B	3.89/11.94 4.32/12.54	12.57	39 (192) 56 (192)	87	75 67	71
HFC-143a (40)	A B	4.92/11.58 4.40/14.10	14.87	42 (192) 55 (192)	86	87 78	83
HFC-143a (50)	A B	4.27/13.27 4.71/13.23	14.88	43 (192) 52 (192)	87	85 82	84
HFC-143a (60)	A B	4.47/11.58 3.63/11.47	11.68	30 (192) 39 (192)	107	97 67	82
HFC-143a (70)	A B	4.41/11.53 3.87/11.72	12.03	52 (192) 48 (192	84	67 63	65
MMS (10 μg/mL)	A B	5.20/10.89 3.92/11.78	12.85	61 (192) 49 (192)	78	65 64	65
* Number of non-colony bearing wells (total number of wells) ** control = Sterile air # Actual concentration reported MMS - Methyl methanesulphonate RTG - Relative Total Growth

Table 3: Additional main mutation test – 3-hour treatment in the absence of S9mix, mutation frequency

Treatment / Nominal concentration (% v/v)	Replicate ID	Mutant Plate Count* Day 2			Mean RTG (%)		Mean MF (x10 ^-6)
Vehicle Control**	A B C D	160 (192) 157 (192) 159 (192) 159 (192)			100		93
HFC-143a (22.3#)	A B	159 (192) 159 (192)			71		108
HFC-143a (40)	A B	163 (192) 160 (192)			83		101
HFC-143a (50)	A B	159 (192) 163 (192)			82		101
HFC-143a (60)	A B	157 (192) 162 (192)			82		86
HFC-143a (70)	A B	160 (192) 156 (192			65		116
MMS (10 μg/mL)	A B	52 (192) 55 (192)			65		818
* Number of non-colony bearing wells (total number of wells) ** control = Sterile air # Actual concentration reported MMS - Methyl methanesulphonate RTG - Relative Total Growth MF - Mutant Frequency

Table 4: Additional main mutation test – 3-hour treatment in the absence of S9mix, colony size analysis

Treatment / Nominal concentration (% v/v)	Replicate ID	Small Mutant Plate Count* Day 2			Mean Small Colony MF (x10^-6)		Large Mutant Plate Count* Day 2	Mean Large Colony MF   (x10^-6)
Vehicle Control**	A B C D	175 (192) 176 (192) 176 (192) 174 (192)			45		173 171 173 173	52
MMS (10 μg/mL)	A B	69 (192) 72 (192)			641		146 151	164
* Number of non-colony bearing wells (total number of wells) ** control = Sterile air MMS - Methyl methanesulphonate RTG - Relative Total Growth MF - Mutant Frequency

Conclusions:

The substance did not demonstrate mutagenic potential in this in vitro cell mutation assay in the presence or absence of a metabolic activation system, under the experimental conditions described.

Executive summary:

The mutagenic potential of the substance was evaluated by testing its ability to induce forward mutations at the thymidine kinase (TK) locus in L5178Y mouse lymphoma cells, either in the absence or presence of a metabolic system (S9-mix) according to the most recent OECD guideline in compliance with GLP. This test system is based on detection and quantitation of forward mutation in the subline 3.7.2c of mouse lymphoma L5178Y cells, from the heterozygous condition at the thymidine kinase locus (TK^+/-) to the thymidine kinase deficient genotype (TK^-/-).

The study consisted of a preliminary toxicity test and three independent mutagenicity assays. The cells were exposed for either 3 hours in the absence of exogenous metabolic activation (S9 mix) or 3 hours in the presence of S9 mix. The substance was tested up to a maximum final concentration of 70% v/v in the preliminary toxicity test, in order to test up to the maximum achievable concentration in the test system without detrimental effects on the cell culture. 

Following a 3-hour exposure to the substance at concentrations from 1 to 70% v/v, no reduction in the relative suspension growth (RSG) was observed in the absence or presence of S9 mix. The concentrations assessed for determination of mutant frequency in the main test were based upon these data, the objective being to test up to the maximum achievable concentration in the test system without detrimental effects on the cell culture.

Following 3-hour treatment in the absence and presence of S9 mix, there were no increases in the mean mutant frequencies of any of the test concentrations assessed that exceeded the sum of the mean concurrent vehicle control mutant frequency and the Global Evaluation Factor (GEF), within acceptable levels of toxicity. The maximum concentration assessed for mutant frequency in the 3-hour treatment in the absence and presence of S9 mix was 70% v/v. In the both the absence and presence of S9 mix there was no significant reduction in RTG.

In all tests the concurrent vehicle and positive control were within acceptable ranges.

It was concluded that the substance did not demonstrate mutagenic potential in this in vitro cell mutation assay, under the experimental conditions described.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 478

Principles of method if other than guideline:

The study was conducted to satisfy the requirements of pharmaceutical product registration.

GLP compliance:

yes

Type of assay:

mammalian cell gene mutation assay

Species / strain / cell type:

mammalian cell line, other: Mouse lymphoma L51787

Metabolic activation:

with and without

Metabolic activation system:

Liver homogenate derived from rats pre-treated with Aroclor 1254

Test concentrations with justification for top dose:

Concentrations up to 100% v/v of the available head space

Vehicle / solvent:

Not applicable

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

other: Not applicable

Positive controls:

other: Unidentified gaseous positive controls were used

Details on test system and experimental conditions:

Exposure period of 4 hours per day

Species / strain:

mammalian cell line, other: Mouse lymphoma L51787

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not applicable

Untreated negative controls validity:

not specified

Positive controls validity:

other: Results not reported

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

-ve with or without metabolic activation

Executive summary:

HFC 134a was not mutagenic to mouse lymphoma L51787 cells with or without metabolic activation.

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with appropriate positive and negative controls

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test concentrations with justification for top dose:

0, 100.000, 300.000, 500.000, 700.000 and 900.000 ppm

Vehicle / solvent:

none

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Remarks:

2-aminoanthracene, 2-nitrofluorene, sodium azide, 9-aminoacridine, benzo[a]pyrene and N-ethyl-N'-nitro-N-nitrosoguanidine

Positive control substance:

benzo(a)pyrene

Remarks:

several positive controls used

Details on test system and experimental conditions:

METHOD OF APPLICATION: as a vapor above the cell cultures for 48 hrs. The cells were then removed from the test atmosphere and incubated for an additional day. All strains were evaluated in duplicate at every exposure concentration. It was noted that cytotoxicity was seen in several cultures at exposure levels of 90%, indicating that the test material did reach the cells.















OTHER:

Evaluation criteria:

A substance is classified as positive when the average number of revertants in any strain at any test substance concentration is at least two times greater than the average number of revertants in the negative control and there is a positive dose response.

Statistics:

none

Species / strain:

other: Salmonella typhmurium strains TA 98, TA 1538, TA 100, TA 1535, and TA 1537 as well as escherica coli WP2 uvrA

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

not applicable

Untreated negative controls validity:

not specified

Positive controls validity:

valid

Additional information on results:

It was concluded that Forane 143a did not exhibit any mutagenic activity in this test system

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

The mutagenic potential of Forane 143a was evaluated in 6 bacterial systems both in the absence and presence of metabolic activation, using exposure levels up to 90 or 100% in the air above the cell cultures. No mutagenic activity was observed.

Executive summary:

Forane 143a was not mutagenic in this assay using vapor exposure up to 90% with 6 bacterial strains. Positive controls were positive demonstrating that the assay was valid.

Reference 4

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

48 hours

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline study conducted under GLPs

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

escherichia coli WP2 uvrA was also included

Principles of method if other than guideline:

OECD Guideline 472 was also followed for the e. coli.

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test concentrations with justification for top dose:

3.5%, 2.5% 1.5% and 0.5% in air above cell cultures.

Vehicle / solvent:

administered as pure gaseous material in the air above the cell cultures

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene, 2-nitrofluorene, sodium azide, acridine and methyl methanesulfonate

Evaluation criteria:

A substance is classified as positive when the average number of revertants in any strain at any test substance concentration is at least two times greater than the average number of revertants in the negative control and there is a positive dose response.

Statistics:

none

Species / strain:

other: Salmonella typhimurium strains TA100, TA1535, TA97 and TA98 as well as Escherichia coli WP2uvrA(pKM101)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Remarks:

substance is a flamable gas, tested up to 50% lower flame limit

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

There was no evidence of mutagenic activity in any test strain either in the absence or presence of S-9 metabolic activation.

Executive summary:

HFC-143a was evaluated for mutagenic activity in 5 bacterial strains both in the absence and presence of metabolic activation. The maximum exposure level of 35000 ppm was 50% of the lower explosivity limit for this material. No mutagenic activity was seen.

Reference 5

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

1984

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: non GLP study conducted at only one exposure level with only two strains of Salmonella

Principles of method if other than guideline:

Only one exposure level and two bacterial strains TA100 and TA1535

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium TA 100

Species / strain / cell type:

S. typhimurium TA 1535

Metabolic activation:

with and without

Metabolic activation system:

S-9

Test concentrations with justification for top dose:

500000 ppm

Untreated negative controls:

yes

Remarks:

trichloroethane

Negative solvent / vehicle controls:

not specified

Positive controls:

yes

Remarks:

vinyl chloride

Evaluation criteria:

A doubling of the revertant rate seen in the control was taken as a positive response.

Statistics:

none

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

positive

Remarks:

9.5 fold increase

Cytotoxicity / choice of top concentrations:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

positive

Remarks:

17.6 fold increase

Cytotoxicity / choice of top concentrations:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

Interpretation of results (migrated information):
positive

Author concluded that test showed HFC-143a to be a weak mutagen. However, this result was not replicated in subsequent a subsequent GLP study at even higher exposure levels.

Executive summary:

Author concluded that test showed HFC-143a to be a weak mutagen. However, this result was not replicated in subsequent a subsequent GLP study at even higher exposure levels.

Reference 6

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

44-46 hrs

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study using current protocol

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

lymphocytes: human

Details on mammalian cell type (if applicable):

male and female doners (one each)

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

S-9

Test concentrations with justification for top dose:

0 (control), 5000, 15000, 25000 and 35000 ppm in air

Vehicle / solvent:

none

Untreated negative controls:

other: air exposure

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

mitomycin C

Remarks:

Migrated to IUCLID6: also cyclophosphamide for activated testing

Details on test system and experimental conditions:

Cells were exposed to HFC-143a for 44-46 hrs. They were then harvested and incubated for 18-20 hrs. @ 37 deg. C.

Evaluation criteria:

50 metaphase cells were scored from each culture. Test was considered to be positive if the percent abnormal cells in at least one treated group was statistically significantly higher that the negative control and there was a statistically significant dose-related increase in the percent of abnormal cells.

Statistics:

The proportion of cells with more than one aberration were compared to the negative control using a Fischer Exact test. A Cochran-Armitage test was also done for linear dose response.

Species / strain:

lymphocytes:

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

not applicable

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: strain/cell type: Human lymphocytes

Remarks:

Migrated from field 'Test system'.

No statistically significant increases in chromosomally abnormal cells occurred at any test concentration or harvest time examined. In this study the test substance was not active.

Conclusions:

Interpretation of results (migrated information):
negative

No statistically significant increases in chromosomally abnormal cells occurred at any test concentration or harvest time examined. In this study the test substance was not active.

Executive summary:

No statistically significant increases in chromosomally abnormal cells occurred at any test concentration or harvest time examined. In this study the test substance was not active.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

A structurally related substance (1,1,1,2-tetrafluoroethane) was negative in a reliable in vivo micronucleus assay and an in vivo dominant lethal assay.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 483 (Mammalian Spermatogonial Chromosome Aberration Test)

GLP compliance:

yes

Type of assay:

rodent dominant lethal assay

Species:

mouse

Strain:

CD-1

Sex:

male/female

Route of administration:

inhalation

Duration of treatment / exposure:

5 days

Frequency of treatment:

6 hours / day

Remarks:

Doses / Concentrations:
0, 1000, 10000, 50000ppm
Basis:

No. of animals per sex per dose:

15 males / 30 females

Control animals:

yes, concurrent no treatment

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

not specified

Negative controls validity:

valid

Conclusions:

Interpretation of results (migrated information): negative

Executive summary:

In a dominant lethal assay, CD1 male mice were exposed to up to 50000ppm HFC 134a for 5 days. After the last exposure, each male was housed with 2 virgin females for 4 consequetive nights. Further matings with new females were conducted at weekly intervals for a total of 8 times. The study indicated that HFC 134a did not affect male fertility or cause mutagenic effects through sperm.

Reference 2

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted using current protocol

Qualifier:

according to guideline

Guideline:

EPA OTS 798.5395 (In Vivo Mammalian Cytogenics Tests: Erythrocyte Micronucleus Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

micronucleus assay

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

Mice were individually housed during the experimental phase of the study. They were maintained in a room at 23 +/- 2 deg. C and humidity 50 +/- 10 %. They were given tap water and Purina Lab Chow #5002 ad libitum during non exposure periods. Rooms were maintained on a 12-hr light - dark cycle.

Route of administration:

inhalation: gas

Vehicle:

none

Details on exposure:

Exposures were conducted in 1.4 m3 chambers for 6 hr/day for 2 consecutive days.

Duration of treatment / exposure:

6-hr/day for 2 days

Frequency of treatment:

2 exposures

Post exposure period:

24 and 48 hrs for fgroups of 5 male and 5 female mice.

Remarks:

Doses / Concentrations:
0 (control), 2000, 10000 and 40000 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

10

Control animals:

yes, sham-exposed

Positive control(s):

cyclophosphamide

Tissues and cell types examined:

bone marrow

Details of tissue and slide preparation:

Bone marrow was collected by centrifugation and collected in fetal bovine serum. At least 3 slides were prepared per animal and fixed in methanol for 8 minutes. The slides were then stained.

Evaluation criteria:

Representative slides from each animal were examined blind. The number of micronucleated cells was recorded per 1000 cells counted.

Statistics:

analysis used one way Analysis of Variance (ANOVA). ANOVA calculations were conducted using the VMS program "Dunnettstats".

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

not applicable

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

The upper exposure level was 50% of the lower flamability level, This was set due to safety concerns. There were no significant differences in mean %MNPCE, in mean %PCE or in mean PCE/NCE ratios.

Conclusions:

Interpretation of results (migrated information): negative
Under the conditions of this test, HFC-143a did not induce micronuclei in bone marrow cells of mice . The test material was not active even at the highest concentration which could be tested (40,000 ppm, 50% of the lower flammability limit) for safety reasons.

Executive summary:

Under the conditions of this test, HFC-143a did not induce micronuclei in bone marrow cells of mice. The test material was not active.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Justification for classification or non-classification

Overall, negative results were consistently reported in a variety of reliable in vitro and in vivo genotoxicity studies. Therefore, the substance does not meet the requirement for classification.