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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
6 November 1988 to 22 December 1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
- dams exposed days 7 - 19 of pregnancy
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
HFC 134a (1,1,1,2-tetrafluoroethane was supplied by Du Pont, Wilmington, Delaware, USA as a liquefied gas, whose composition conformed to that acceptable to the testing consortium for toxicity study grade material. The purity was >99.9%. The sponsor provided information to demonstrate the stability of HFC 134a over the period of the study. The batch reference number was 110A500W and the compound was identified by the CTL reference number Y00035/012/002.

Test animals

Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Interfauna UK (Huntingdon Cambridge UK)
- Age at study initiation:
- Weight at study initiation: 2.8 - 4.0 kg on insemination (Day 1 of gestation)
- Housing: individually in suspended stainless steel cages
- Diet (e.g. ad libitum): ad libitum during non-exposure periods
- Water (e.g. ad libitum): ad libitum druing non-exposure periods
- Acclimation period: at least 7 days prior to insemination


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 15 - 19°C
- Humidity (%): 55 - 90%
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12 / 12


IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure (if applicable):
whole body
Vehicle:
unchanged (no vehicle)
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: rotary steel and glass chambers 3.4m3
- Method of holding animals in test chamber: steel cages
- Source and rate of air: 700 litres / min
- Temperature, humidity, pressure in air chamber: 23 ±3°C (measured 20.5°C - 23.5°C; 40-60% RH (measured 48 - 68%)
- Air flow rate: 700 litres / min
- Air change rate: 12/hr


TEST ATMOSPHERE
- Brief description of analytical method used: autoimatic sampling and analysis by Gas Chromatograph
- Samples taken from breathing zone: yes


Analytical verification of doses or concentrations:
yes
Details on mating procedure:
- Impregnation procedure: [artificial insemination}
Duration of treatment / exposure:
from days 7 to 19 of gestation
Frequency of treatment:
6 hours / day
Duration of test:
30 days
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 2500, 10000, 40000 ppm
Basis:

No. of animals per sex per dose:
28 females per exposure group
Control animals:
yes, concurrent no treatment
Details on study design:
Groups of 28 rabbits were used and exposure concentrations were nominally 0 (control), 2500, 10000 and 40000ppm HFC 134a on days 7 through 19 of pregnancy. Animals were assigned randomly to each group. Pregnancy was induced through artificial insemination using sperm collected from males of proven fertility. After insemination each female was given an intravenous injection of 25 IU chorionic gonadotrophin to promote ovulation.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule:



DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily


BODY WEIGHT: Yes
- Time schedule for examinations: Days 1 and 4 and 7 - 19 (inclusive) and on Days 22, 26, 30 of gestation.


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes / No / No data
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes / No / No data
- Time schedule for examinations:


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 30
- Organs examined: gravid uterus, ovaries


OTHER:
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Fetal examinations:
- External examinations: Yes: [all per litter ]
- Soft tissue examinations: Yes: [all per litter ]
- Skeletal examinations: Yes: [all per litter]
- Head examinations: Yes: [all per litter ]
Statistics:
Data relating to animals which were non-pregnant or had aborted their litters were excluded from the statistical analysis. Maternal body weight gain and food consumption, number of implantations and live fetuses per female, percentage pre- and postimplantation loss, percentage of implantations which were early or late intrauterine deaths, gravid uterus weight, litter weight, mean fetal weight, mean manus and pes scores per fetus, and percentage of fetuses with minor external/visceral defects only and skeletal defects only were considered by analysis of variance. Analyses were carried out using the GLM procedure in SAS (1985). Each treatment group mean was compared with the control group mean using Student's t test based on the error mean square in the analysis. Fetal data were converted to the litter level before calculating group means or carrying out analyses of variance. Percentages were transformed before analysis using the double arcsine transformation of Freeman and Tukey (1950). The proportion of females with pre- and postimplantation loss, early and late intrauterine deaths, the proportion of male fetuses, the proportion of fetuses with major or minor (only) external/visceral defects, major or minor (only) skeletal defects, skeletal variants, and individual variants were analysed by Fischer's exact test, comparing each group with the control group. All statistical tests were one-sided, except maternal bodyweight gain, maternal food consumption, and the proportion of male fetuses, which were two sided.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
The dams in the groups exposed to 10000 and 40000ppm HFC 134a had a lower rate of body weight gain than the controls. In the group exposed to 40000ppm this was partially compensated for by an increase in body weight gain during the post exposure phase (Days 19 -30). During the exposure phase food consumption was lower in the group at 40000ppm and to a lesser extent at 10000ppm compared to the controls. It is considered that the difference in maternal body weight gain between controls and dams in the group at 40000ppm was small but represents slight maternal toxicity. The difference at 10000ppm was very small, and at most may represent a minimal maternal effect.

Effect levels (maternal animals)

Dose descriptor:
NOEL
Effect level:
2 500 ppm
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The mean numbers of corpora lutea, implantations, and live fetuses were similar across the control and all treatment groups (Table A).
Also the ratio of sexes of the pups was not affected by treatment. Gravid uterus, litter, and pup weights were similar across all groups, and there was no evidence of any adverse developmental effects associated with exposure to HFC 134a (Table B).

Effect levels (fetuses)

open allclose all
Dose descriptor:
NOEL
Effect level:
40 000 ppm
Basis for effect level:
other: embryotoxicity
Dose descriptor:
NOEL
Effect level:
40 000 ppm
Basis for effect level:
other: fetotoxicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Table A. HFC 134a: Developmental Toxicity Study in the Rabbit (Intergroup Comparison of Litter Data)

Exposures were for 6 hours/day on Days 7 through 19 of pregnancy. There were no significant differences (Student's t test) from control values.

   0 (control)  2500ppm  10000ppm  40000ppm
 Number of females mated  28  28  28  28
 Number of females with live fetuses in utero at termination  23  18 21   23
 Mean n corpora lutea  10.7  10.2  10.4  10.5
 Preimplantation loss        
 Mean percentage  20.4  19.3  22.0  14.6
 Prop. of females affected  16/23  13/18  16/21  15/23
 Mean n implantations  8.48  8.11  8.33  9.09
 Postimplantation loss        
 Mean percentage  9.5  8.8  9.0  13.2
 Prop. of females affected  11/23  7/18  10/21  13/23
 Mean n live fetuses  7.61  7.39  7.43  7.87
 Intrauterine deaths        
 Number early  9  11  5  10
 Mean percentage early  5.2  7.4  3.1  5.3
Prop. females affected  6/23  6/18  5/21  5/23
 Number late  11  2  14  18
 Mean percentage late  4.3  1.4  5.9  8.0
 Prop. of females affected  6/23  1/18  8/21  11/23

Table B. HFC 134a: Developmental Toxicity Study in the Rabbit (Intergroup Comparison of Litter Data).

Exposures were for 6 hr/day on Days 7 through 19 of pregnancy. *Mean values are based on the number of females with live fetuses in utero at termination. There were no significant differences (Student's t test) from control values.

   0 (control)  2500ppm  10000ppm  40000ppm
 Total No. of live fetuses  175  133  156  181
Mean gravid uterus weight (g)  470*  461 443  480
 Mean litter weight (g)  311  311  284  309
 Mean fetal weight (g)  41.8  43.9  40.9  41.0
Skeletal defects        
No. of fetuses showing major defects  1  1  2
 Percentage  0.6  0.8  0.6  1.1
No. of fetuses showing minor defects only  111  77  95  105
 Percentage  63  58  61  58
 External / visceral defects        
 No. of fetuses showing major defects  1  1  0  2
 Percentage  0.6  0.8  0  1.1
 No. of fetuses showing minor defects only  73  41  70  68
 Percentage  42  31 45  38

Applicant's summary and conclusion

Conclusions:
There was no evidence for maternal toxicity at the exposure level of 2,500 ppm. There was no evidence of embryotoxic, teratogenic or foetotoxic effects at any exposure level of HFC 134a.
Executive summary:

Female New Zealand White rabbits (28/group) were exposed (6 h/d) by inhalation to 0, 2,500, 10,000 and 40,000 ppm (0, 10,420, 41,700, 167,000 mg/m3) HFC-134a from days 7 to 19 of gestation. Exposure to concentrations of 10,000 and 40,000 ppm HFC-134a was associated with slight maternal toxicity manifest as reduced body weight gain and food consumption. There was no evidence for maternal toxicity at the exposure level of 2,500 ppm. There was no evidence of embryotoxicity, teratogenicity or foetotoxicity at any exposure level.