Registration Dossier

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 labelling and/or risk assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report Date:
1994

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Purity: 99.7%

Test animals

Species:
rat
Strain:
other: Crl:CD®BR
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: females were approximately 63 days old on the date of arrival; males were approximately 77 days old on the date of arrival
- Weight at study initiation: Females were 250.0-312.6 g on day 1G
- Fasting period before study: No
- Housing: Individually in suspended, wire-mesh, stainless steel cages
- Diet (e.g. ad libitum): ad libitum, except during inhalation exposures
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 6 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23±2°C
- Humidity (%): 50±10%
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12-hour dark/12-hour light

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure (if applicable):
whole body
Vehicle:
other: air
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Glass and stainless steel chambers of approximately 750 L volume. Control modules were in a 1000-L chamber
- Method of holding animals in test chamber: Individually housed in a stainless steel, wire basket, exposure module
- Source and rate of air: Filtered, conditioned air
- Method of conditioning air: Not reported
- System of generating particulates/aerosols: Test atmospheres were generated by metering the liquid test material into a J-tube filled with glass beads. Heated air, approximately 60°C, was blown through the glass beads to evaporate the test material. The resulting vapour was diluted by filtered, conditioned air to the target concentration for each of the test chambers. Conditioned, heated air alone was metered in an identical manner into the control chamber. The chambers were operated in a one-pass, flow-through mode to enable adequate distribution of the test material throughout the chamber, to provide sufficient oxygen for the test animals, and to prevent contamination from volatiles derived from excreta. The position of the exposure modules within each chamber was rotated each day to minimize any possible effects of uneven vapour distribution. At the end of each exposure, rats remained in their chambers long enough to allow clearance of the test material from the chamber atmosphere.
- Temperature, humidity, pressure in air chamber: 17-27°C, 23-100%, pressure not reported
- Air flow rate: Not reported
- Air change rate: at least 12 air changes per hour
- Method of particle size determination: Not reported
- Treatment of exhaust air: Chamber exhaust was diluted with room air and exhausted through a roof stack.

TEST ATMOSPHERE
- Brief description of analytical method used: Chamber atmospheres were analyzed at least hourly during each 6-hour exposure period by gas chromatography. The isomer ratio in an air sample collected from one of the test chambers was determined once daily.
- Samples taken from breathing zone: yes
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Method of Analysis: GC

Mean chamber concentrations were always within 10% of the targeted concentration, with the exception of two minor excursions. The mean concentrations achieved for the 2000 ppm concentration were slightly low (86 or 81% of target) on two days. Analyses demonstrated that the test substance was stable over the course of the study. Overall mean concentration was 501.8, 1940.3, and 3475.5 ppm for the 500, 1000, and 4000 ppm concentrations, respectively.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: Until copulation was confirmed by the presence of a copulation plug in the vagina or on the cageboard
- Proof of pregnancy: vaginal plug referred to as day 1 of pregnancy
Duration of treatment / exposure:
Gestation Days 7 to 16
Frequency of treatment:
6 hours daily
Duration of test:
Females were sacrificed on gestation day 22
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
502, 1940, 3476 ppm (5174; 20004; 35832 mg/m3, respectively)
Basis:
analytical conc.
Remarks:
Doses / Concentrations:
500, 2000, 3500 ppm (5154; 20618; 36081 mg/m3, respectively)
Basis:
nominal conc.
No. of animals per sex per dose:
25 females
Control animals:
yes
Details on study design:
- Dose selection rationale: A 2-week nose-only inhalation study at 0, 500, 1000, and 4000 ppm revealed minimal compound related effects. A rangefinding study was conducted, with whole-body exposures, for 3 or 4 exposures at 5000 or 7000 ppm. Clinical signs of toxicity, consisting of seizure-like behaviour, occurred at concentrations as low as 3700 ppm. The doses for this study were selected so the highest concentration was below the threshold at which seizure-like activity occurred.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily; to monitor general well-being during inhalation exposure, rats visible through the chamber were observed at approximately hourly intervals, and a response to a noise was measured 3 times during each exposure

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Each morning on Days 1-22G and each afternoon on days 7-16G (the exposure period)

BODY WEIGHT: Yes
- Time schedule for examinations: Days 1, 7, 9, 11, 13, 15, 17, and 22G

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
- Time schedule: Days 1, 7, 9, 11, 13, 15, 17, 19, and 22G

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 22
- Organs examined: Organs of thoracic and abdominal cavities
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: [half per litter]
- Skeletal examinations: Yes: [all per litter]
- Head examinations: Yes: [half per litter]
Statistics:
See Table 1 below

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
Body Weights: Significant dose-related decreases in mean maternal body weight changes were observed at 2000 and 3500 ppm. The reductions were most dramatic at the onset of dosing; mean maternal weight changes were significantly reduced for both groups over Days 7-9 and 9-11G. At 3500 ppm, overall weight gain was significantly reduced for the exposure period (Days 7-17G). In addition, the mean weight gain from Day 7-22G (using the adjusted Day 22G body weight) was significantly lower at 3500 ppm.

Feed Consumption: Mean maternal feed consumption was significantly reduced at 2000 and 3500 ppm. Significant reductions were observed for both groups over Days 7-9, 9-11, 11-13, and 7-17G. In addition, significant reductions were seen over Days 13-15 and 15-17G at 3500 ppm. In general, the reductions in mean maternal feed consumption correlated with the reduced mean maternal body weight gain.

Clinical Observations: Clinical observation incidence was increased at 2000 and 3500 ppm during the exposure period (Days 7-16G) due primarily to an increase in perinasal staining which was significant for both groups. At 3500 ppm, the incidences of staining of the fur on the back, face, head, and wet perineum were significantly increased as well. This fur-staining may be a result of decreased grooming. The animals in this study were exposed concurrently with rats from a subchronic toxicity study, therefore observations recorded during the exposures apply to both groups of animals. While in the chambers, abnormal behaviour that included convulsions, jerking, pawing the air, tremors, and involuntary muscle reflexes, was observed in rats exposed at 2000 and 3500 ppm. These observations are believed to be compound related. Staining of the fur on the back was significantly increased at 3500 ppm during the post-exposure period (Days 17-22G).

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
500 other: ppm (5154 mg/m3)
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
2 000 other: ppm (20618 mg/m3)
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
Mean foetal weight was significantly reduced at 3500 ppm.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The study and the conclusions which are drawn from it fulfil the quality criteria (validity, reliability, repeatability).

Under conditions of this study, significant maternal central nervous system toxicity was demonstrated at daily dose levels of 2000 and 3500 ppm. The maternal NOAEL was 500 ppm. Developmental toxicity, as measured by decreased mean foetal weight, was observed only at 3500 ppm (36081 mg/m3). The developmental NOAEL was 2000 ppm (20618 mg/m3). Therefore, the test substance is not uniquely toxic to the conceptus.
Executive summary:

The test substance was administered by inhalation (whole-body) to groups of 25 Crl:CD®BR female rats on days 7-16 of gestation (Days 7-16G) at daily nominal concentrations of 0, 500, 2000, or 3500 ppm. Significant dose-related decreases in maternal body weight gain and feed consumption occurred at 2000 and 3500 ppm. An increase in clinical observations was seen at these levels as well. The incidence of perinasal staining was significantly increased at 2000 ppm and above. Staining of the fur on the back, face, and neck was significantly increased at 3500 ppm. Observations indicative of abnormal behaviour were recorded during the inhalation exposures and included convulsions and tremors. These observations occurred at 2000 and 3500 ppm and were compound-related. No evidence of maternal toxicity was detected at 500 ppm. Significantly reduced meal foetal body weight, indicative of developmental toxicity, was evident only at the highest dose level, 3500 ppm. No other evidence of developmental toxicity was detected. Under the conditions of this study, significant maternal toxicity was demonstrated at daily dose levels of 2000 ppm and above. The maternal NOAEL was 500 ppm. Developmental toxicity was detected only at 3500 ppm (36081 mg/m3). The NOAEL for developmental toxicity was 2000 ppm (20618 mg/m3). The test substance is not considered to be uniquely toxic to the conceptus.