Trifluoro(trifluoromethyl)oxirane

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labeling and/or risk assessment.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Remarks:

Study included FOB and motor activity endpoints.

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EPA OPPTS 870.3650

Deviations:

yes

Remarks:

Study included FOB and motor activity endpoints

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Trifluoro(trifluoromethyl)oxirane

EC Number:

207-050-4

EC Name:

Trifluoro(trifluoromethyl)oxirane

Cas Number:

428-59-1

Molecular formula:

C3F6O

IUPAC Name:

2,2,3-trifluoro-3-(trifluoromethyl)oxirane

Details on test material:

- Purity: >99%

Test animals

Species:

rat

Strain:

other: Crl:CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Approximately 66 days
- Weight at study initiation: Males: 170.0–235.2 g; Females: 169.1–213.1 g
- Fasting period before study: no data
- Housing:
Pretest/Premating: Individually (except during cohabitation of mating pairs) in stainless steel, wire-mesh cages suspended above cage boards; sexes on separate racks.
Cohabitation: Mating pairs (females placed in males’ cages) on a 1:1 basis in stainless steel, wire-mesh cages suspended above cage boards.
Days 0–19 of gestation: Individually in stainless steel, wire-mesh cages suspended above cage boards; sexes on separate racks.
Day 19 of gestation - Day 4 of lactation: Females assumed pregnant were housed individually in polycarbonate pans with bedding material. Females presumed nonpregnant were housed in the same manner as pregnant females approximately 6 days after the mating pairs were separated.
- Diet (e.g. ad libitum): PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002 (pelleted); ad libitum
- Water (e.g. ad libitum): Tap water from United Water Delaware; ad libitum
- Acclimation period: Pretest Period: 14 days; Quarantine: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18–26°C
- Humidity (%): 30%–70%
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12-hour light/dark

Administration / exposure

Route of administration:

inhalation: gas

Type of inhalation exposure (if applicable):

whole body

Vehicle:

other: filtered and conditioned air

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: All exposure chambers were constructed of stainless steel and glass (NYU style) with a nominal internal volume of 350 L. A tangential feed at the chamber inlet promoted uniform chamber distribution of the test atmosphere.
- Method of holding animals in test chamber: During exposure, animals were individually placed in stainless steel wire-mesh modules (one/module) and exposed, whole-body, inside the exposure chamber, except during the mating period when animals were housed as mating pairs in stainless steel wire-mesh modules and exposed in the same manner.
- Source and rate of air: filtered and conditioned air
- Method of conditioning air: filtered and conditioned air
- System of generating vapour: Chamber atmospheres were generated by dilution of the test vapour in air. The test substance was metered into the test chamber inlets using a Brooks model 0145 or 0145E mass flow controller and mixed with filtered and conditioned air, which carried the resulting atmosphere into the exposure chamber. Chamber concentrations of test substance were manually controlled by varying the test substance feed rate to the chamber.
- Temperature, humidity, pressure in air chamber: 19–24°C; 41–82%; pressure not reported
- Air flow rate: 70–114 L/min
- Air change rate: at least 10 air changes per hour
- Treatment of exhaust air: to fume hood

TEST ATMOSPHERE
- Brief description of analytical method used: During each exposure, the atmospheric concentration of the test substance was determined by
gas chromatography at approximately 30-minute intervals in the test chambers. A gas chromatograph equipped with an automated gas sample valve and a flame ionization detector was used.
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Method of Analysis:
The mean concentrations (± standard error of the mean) of the test substance were 50 ± 0.098 and 250 ± 0.16 ppm in chambers targeted at 50 and 250 ppm, respectively. The mean concentration ± standard error of the mean) for the high concentration chamber was 580 ± 30 ppm. The reason for the relatively high standard error of the mean for the high concentration chamber was because the concentration was targeted to 1000 ppm for the first 6 exposures, and then targeted to 500 ppm for the remainder of the study. Overall daily mean concentrations ranged from 49-52 ppm for the 50 ppm chamber, 250 ppm for the 250 ppm chamber, and 500–1000 ppm for the 1000/500 ppm chamber. The calculated nominal concentrations were generally similar to the actual measured concentrations, with mean nominal concentrations of 58, 264, 564, and 1085 ppm for the 50, 250, 500, and 1000 ppm targeted concentrations, respectively. These data demonstrate that the exposure system and analyses were operating as expected.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: up to 14 days
- Proof of pregnancy: Daily examination of each female for an intravaginal copulation plug or sperm in the vaginal lavage sample.
- Further matings after two unsuccessful attempts: No
- After successful mating each pregnant female was caged (how): Days 0–19 of gestation: Individually in stainless steel, wire-mesh cages suspended above cage boards; sexes on separate racks. On day 19 of gestation for mated females or 6 days after the mating pairs were separated for females without evidence of copulation, females were transferred into polycarbonate pans.

Duration of treatment / exposure:

Exposures for males and females were conducted for the 14 day premating period. Subsequently, males and non-pregnant females were exposed through to the terminal sacrifice. Exposures for females with evidence of mating were conducted during the cohabitation period (up to 2 weeks in duration) and during gestation days 0–19. Gestating P1 females were not exposed after gestation day 19.

Premating period - 14 days exposure
Cohabitation - Up to 14 days exposure

Postcohabitation Exposure:
Males - Up to test days 36–37
Females with no evidence of mating - 19 days (approximate)
Gestation - (GD 0-19)
Lactation - No exposure (LD 0-4)

Frequency of treatment:

All exposures were conducted for 6 hours/day, 5 days/week during the premating period. Beginning at the mating (cohabitation) period, exposures were conducted for 6 hours/day, 7 days per week. Lactating dams were not exposed.

Duration of test:

GESTATION:
After being transferred into polycarbonate pans (on day 19 of gestation for mated females, or 6 days after the mating pairs were separated for females without evidence of copulation), female rats were observed at least twice daily for signs of delivery and offspring.

LACTATION:
On lactation days 0 and 4, offspring were individually handled and examined for abnormal behavior and appearance; any dead or abnormal pups were recorded. On Day 0 (Day of deliver = Day 0 of lactation) live and dead pups in each litter were counted by sex and live pups were individually weighed as soon as possible after delivery was completed. On Day 4 (litter sacrifice), pups in each litter were counted by sex and live pups were individually weighed and a gross external examination was performed. If litters died prior to Day 4 of lactation, the female was sacrificed. If the female died prior to Day 4 of lactation, the litter was sacrificed. If individual pups died prior to Day 4 of lactation, the carcass was examined to the extent possible and discarded. F1 pups were not necropsied, organs were not weighed, and there was no microscopic evaluation.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 250, 1000/500 ppm (the high level concentration was reduced to 500 ppm on test day 9 [exposure #7])
Basis:
nominal conc.

No. of animals per sex per dose:

12 females

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: The test substance is slightly toxic in the rat by the inhalation route with a 2.5-hour ALC of 2000 ppm. The only signs of toxicity observed in rats exposed at 400 ppm in a 2-week inhalation study (4 hr/day; 5 days/wk) were inactivity and slightly deepened respiration; pathological examination revealed no test substance-related changes. No effects on body weight or food consumption were observed nor were there any clinical signs of toxicity in rats exposed at 100 or 400 ppm for 18-weeks (6 hr/day; 5 days/wk). Significant changes in organ/body weight ratios (spleen, kidneys and adrenals in males; liver in females) occurred at 400 ppm. Based on these results, the concentrations selected for the current study are 0, 50, 250, and 1000 ppm. However, due to excessive toxicity, the 1000 ppm concentration was reduced to 500 ppm on test day 9.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: once daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once during pretest (baseline), and weekly thereafter.

BODY WEIGHT: Yes
- Time schedule for examinations:
Quarantine: Twice
Pretest: Weekly
Cohabitation: Weekly
Post-cohabitation: Weekly for males and females without evidence of copulation
Gestation: Days 0, 7, 14, 21G
Lactation: Days 0, 4L
Sacrifice: All animals

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
Premating: Weekly
Cohabitation: None
Post-cohabitation: None for males and females without evidence of copulation
Gestation: Days 0, 7, 14, 21G
Lactation: Days 0, 4L

POST-MORTEM EXAMINATIONS: Yes
SACRIFICE SCHEDULE:
Males - After siring litters (approximately 28 days of exposure)
Dams with Litters - Day 4L
Females without evidence of mating - Approximately 26 days after end of cohabitation
F1 litters - PND 4
Gross Pathology - All animals. Uterine implantation sites and ovarian corpora lutea were counted in P1 females.
Organ Weights - All animals
Histopathology - Control and high-dose groups (target organs and gross lesions in intermediate-dose groups)

OTHER:
FOOD EFFICIENCY:
- Calculation of Food Consumption:
Feeders were weighed at the beginning and end of the interval. The final weight and amount of spillage (greater than 5 g) were subtracted from initial feeder weight.
- Calculation of Mean Daily Food Efficiency:
From food consumption and body weight data.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: first 5 surviving male and female animals on test day 17
- Anaesthetic used for blood collection: Yes (carbon dioxide)
- Animals fasted: Yes
- How many animals: 5 each sex
- Parameters checked in table [No.1] were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: first 5 surviving male and female animals on test day 17
- Animals fasted: Yes
- How many animals: 5 each sex
- Parameters checked in table [No.2] were examined.

NEUROBEHAVIOURAL EXAMINATION: Yes, (refer to Section 7.9.1, DI.K1.Neuro.R.D-20964 for additional details).
- Time schedule for examinations: Prior to initiation of test substance administration and prior to the end of the premating period
- Dose groups that were examined: all
- Battery of functions tested: Abbreviated Functional Observational Battery (FOB), Motor Activity Evaluation

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: No
- Number of late resorptions: No

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: No
- Skeletal examinations: No
- Head examinations: No

On lactation days 0 and 4, offspring were individually handled and examined for abnormal behavior and appearance; any dead or abnormal pups were recorded. On Day 0 (Day of deliver = Day 0 of lactation) live and dead pups in each litter were counted by sex and live pups were individually weighed as soon as possible after delivery was completed. On Day 4 (litter sacrifice), pups in each litter were counted by sex and live pups were individually weighed and a gross external examination was performed. If litters died prior to Day 4 of lactation, the female was sacrificed. If the female died prior to Day 4 of lactation, the litter was sacrificed. If individual pups died prior to Day 4 of lactation, the carcass was examined to the extent possible and discarded. F1 pups were not necropsied, organs were not weighed, and there was no microscopic evaluation.

Gross Examination of Dead Pups: Yes, for external abnormalities; possible cause of death was determined for pups born or found dead.

Statistics:

Male and female data were evaluated separately. For litter parameters, the proportion of affected pups per litter or the litter mean were used as the experimental unit for statistical evaluation. The level of significance selected was p < 0.05.
see Table 4 Materials and Methods tables below

Indices:

Refer to Table 5 for reproductive indices calculated.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
CLINICAL SIGNS AND MORTALITY: Refer to Section 7.5.2, DI.K1.28Day.InhGas.RD/REPRO/DEV.R.D-20964.KD for details.

BODY WEIGHT AND FOOD CONSUMPTION: Refer to Section 7.5.2, DI.K1.28Day.InhGas.RD/REPRO/DEV.R.D-20964.KD for details.

HAEMATOLOGY: Refer to Section 7.5.2, DI.K1.28Day.InhGas.RD/REPRO/DEV.R.D-20964.KD for details.

CLINICAL CHEMISTRY: Refer to Section 7.5.2, DI.K1.28Day.InhGas.RD/REPRO/DEV.R.D-20964.KD for details.

HISTOPATHOLOGY / ORGAN WEIGHTS: Refer to Section 7.5.2, DI.K1.28Day.InhGas.RD/REPRO/DEV.R.D-20964.KD for details.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEC

Effect level:

50 ppm (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEC

Effect level:

50 ppm (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
VIABILITY (OFFSPRING): The failure of 3 P1 adult pairs to produce a litter was not test substance related. One 50 ppm pair and one 250 ppm pair had no gross or microscopic pathology to explain their reproductive failure. The reproductive failure of another 250 ppm pair was apparently due to decreased ovulation by the female as evidenced by decreased corpora lutea.

There were no test substance-related or statistically significant differences in mean number of pregnant animals, number of animals delivering, mating index, fertility index, precoital interval, gestation length, number of corpora lutea, number of implantation sites, or percent of postimplantation loss for any exposure concentration. There were no test substance-related or statistically significant differences in number of litters born, number of pups born or born alive, live born index, viability index, sex ratio, or incidence of clinical observations.

BODY WEIGHT (OFFSPRING): Adverse, test substance-related decreases in pup weight occurred in the 250 ppm and above groups. Pup weight for the 250 and 1000/500 ppm groups was significantly lower compared to the control mean on postnatal day 4.
See Table below.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Mean Pup Weights
Group:Concentration (ppm)	1 0	2 50	3 250	4 1000/500
PND 0	6.7 0.6(12)	6.4 0.7(11)	6.2 0.7(10)	6.1 0.6(10)
PND 4	11.0	9.8	9.5	9.7
Data summarized as:  Mean Standard Deviation (n)

Applicant's summary and conclusion

Conclusions:

This study and the conclusions which are drawn from it fulfill the quality criteria (validity, reliability, repeatability).
The NOAEL for reproduction was 1000/500 ppm based on the absence of effects at the highest concentration tested.
The NOAEL for offspring was 50 ppm based on the pup body weight effects at 250 ppm and above.

Executive summary:

A combined repeated dose toxicity study with reproduction/developmental toxicity screening test was conducted with the test substance. Crl:CD(SD) rats (12/sex/concentration) were exposed whole body to 0, 50, 250, or 1000/500 ppm. Due to excessive toxicity, the 1000 ppm concentration was reduced to 500 ppm beginning on exposure 7 (test day 9). Exposures for males and females were conducted for 6 hours per day, 5 days per week from the initiation of the study through the 14 day premating period. Subsequently, males and non-pregnant females were exposed 7 days a week through the terminal sacrifice. Exposures for females with evidence of mating were conducted for 6 hours per day, 7 days per week during the cohabitation period (up to 2 weeks in duration) and during gestation days 0–19. Gestating P1 females were not exposed after gestation day 19. An abbreviated neurobehavioral evaluation consisting of a functional observational battery and motor activity was conducted in P1 rats (12/sex/group) once during pretest and prior to cohabitation. Clinical pathology parameters were measured in P1 rats (5/sex/group) at the end of the premating period (hematology, clinical chemistry) and at terminal sacrifice (coagulation). All P1 rats were given a gross pathological examination and selected tissues were weighed and collected from all adult rats. F1 litter examinations (pup viability, individual pup weights, pup sex, and clinical observations) were performed at birth and on lactation day 4. Uterine implantation sites and ovarian corpora lutea were counted in P1 females. There were no test substance-related or statistically significant differences in mean number of pregnant animals, number of animals delivering, mating index, fertility index, precoital interval, gestation length, number of corpora lutea, number of implantation sites, or percent of postimplantation loss for any exposure concentration. There were no test substance-related or statistically significant differences in number of litters born, number of pups born or born alive, live born index, viability index, sex ratio, or incidence of clinical observations. Adverse, test substance-related decreases in pup weight occurred in the 250 ppm and above groups. Pup weight for the 250 and 1000/500 ppm groups was significantly lower compared to the control mean on postnatal day 4. The NOAEL for reproduction was 1000/500 ppm based on the absence of effects at the highest concentration tested. The NOAEL for offspring was 50 ppm based on the pup body weight effects at 250 ppm and above.