Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report Date:
1996

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
yes
Remarks:
Characterization of test substance conducted at a non-GLP compliant lab. Stability of test substance was not evaluated as it was expected to be stable throughout the exposure phase of the study. The deviations did not affect the integrity of the study.
Qualifier:
according to
Guideline:
EU Method B.2 (Acute Toxicity (Inhalation))
Deviations:
yes
Remarks:
Characterization of test substance conducted at a non-GLP compliant lab. Stability of test substance was not evaluated as it was expected to be stable throughout the exposure phase of the study. The deviations did not affect the integrity of the study.
Qualifier:
according to
Guideline:
other: U.S. EPA Health Effects Testing Guidelines, 40 CFR Part 798, Subpart B, Acute lnhalation Toxicity
Deviations:
yes
Remarks:
Characterization of test substance conducted at a non-GLP compliant lab. Stability of test substance was not evaluated as it was expected to be stable throughout the exposure phase of the study. The deviations did not affect the integrity of the study.
Qualifier:
according to
Guideline:
other: MAFF Japan Testing Guideline for Acute Inhalation Toxicity Study (59 NohSan No. 4200), 1985
Deviations:
yes
Remarks:
Characterization of test substance conducted at a non-GLP compliant lab. Stability of test substance was not evaluated as it was expected to be stable throughout the exposure phase of the study. The deviations did not affect the integrity of the study.
GLP compliance:
yes
Test type:
acute toxic class method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
gas
Details on test material:
- Purity: 99%

Test animals

Species:
rat
Strain:
other: Crl:CD BR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, North Carolina, U.S.A.
- Age at study initiation: Approximately 8 weeks
- Weight at study initiation: 265-277 g for males and 179-196 g for females.
- Housing: Except during exposure, rats were housed either singly or in pairs (sexes separate) in suspended, stainless steel, wire-mesh cages.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 6 days

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

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Glass (cylindrical)
- Exposure chamber volume: 29 L
- Method of holding animals in test chamber: During exposure, animals were placed in stainless steel wire mesh cages (sexes separate) and placed inside the exposure chamber.
- System of generating particulates/vapours: Vapour atmospheres of test substance were generated by metering the test substance vapour from a cylinder located in a remote cylinder shed. The test substance vapour flowed through 1/4 inch (O.D.) stainless steel or Teflon tubing and a rotometer prior to entry into the mixing flask. Houseline air added to the mixing flask carried the test substance/air mixture into the exposure chamber. The chamber concentration of test substance was controlled by regulating the flow of test substance vapour through the rotameter. The chamber exhaust was mixed with nitrogen prior to discharge into the fume hood. Prior to the initiation of the test exposure, a study of chamber distribution of vapour concentration was performed. No statistical differences were observed with the Student's t-test (alpha = 0.05), when samples taken at six locations in the exposure chamber were compared to four samples taken from the reference sampling port. The test therefore, was considered to be homogenously distributed throughout the exposure chamber.
- Environmental monitoring: Chamber temperature was targeted at 23 ± 1°C. Temperature was monitored continually with a mercury thermometer and recorded at the beginning of the exposure and four times during the exposure. Due to the flammability of test substance, chamber relative humidity was not measured during the exposure. Chamber oxygen concentration was targeted to at least 19%, and was measured three times during the exposure with a Biosystems model 3100R Oxygen Monitor.
Test atmospheres were generated dynamically with chamber airflow set to achieve at least 12 air changes per hour within the exposure chamber.

Test substance sampling and analysis: The atmospheric concentration of test substance was determined by gas chromatography at approximately five-minute intervals during the first hour of exposure and at approximately fifteen-minute intervals during the remainder of the four-hour exposure. Gas samples were drawn by vacuum pump from a sampling port located in the breathing zone of the rats. Chamber atmosphere samples were directly injected into a Hewlett Packard model 5890 series II Gas Chromatograph equipped with a flame ionization detector for analysis of test substance concentration. All samples were chromatographed isothermally at 50°C on a 60 M RTX-1 column. The atmospheric concentration of test substance was determined from a standard curve derived from gas standards. The gas standards were prepared prior to exposure by injecting known volumes of test substance vapour into gas bags that contained known volumes of air.
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
21000 ppm
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days.
- Mortality, clinical signs and body weights were observed on Day 0, 1, 2, 5, 6, 7, 8, 9, 12, 13, 14 and 15.
- Necropsy of survivors performed: Yes

Results and discussion

Effect levels
Key result
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 21 000 ppm
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: Equivalent to 70% of the lower explosive limit
Mortality:
None of the rats died during exposure or within 14 days following exposure to the test substance.
Clinical signs:
During exposure, rats exhibited diminished response to an alerting stimulus and diminished activity. When rats were removed from the exposure chamber immediately following the exposure, clinical signs of toxicity were limited to irregular respiration in two male rats. This clinical sign of toxicity had resolved by one day following exposure. No clinical signs were apparent during the 14-day recovery period.
Body weight:
One male rat experienced slight weight loss one day following exposure. All male and female rats exhibited an overall weight gain by the end of the 14-day recovery period.
Gross pathology:
Gross pathological examination revealed no evidence of organ-specific toxicity in any of the rats.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
4h LC50 (Male/Female): > 21000 ppm
Executive summary:

One group of five male and five female Crl:CD BR rats was exposed to a vapor atmosphere of the test substance for a single, four-hour exposure period in accordance with OECD Guideline 403. The test substance vapour was analyzed using gas chromatography. During the 14-day recovery period, rats were weighed and observed for clinical signs of toxicity. All rats underwent pathological examination at the end of the recovery period.

Rats were exposed to a chamber concentration of 21000 ppm test substance (equivalent to 70% of the lower explosive limit). All rats survived the exposure and subsequent 14-day recovery period. Clinical signs of toxicity observed included diminished response to an alerting stimulus and diminished activity during exposure and irregular respiration in two of five male rats immediately following exposure. No clinical signs of toxicity were apparent during the 14-day recovery period. One male rat experienced slight weight loss one day following exposure. All male and female rats exhibited an overall weight gain by the end of the 14-day recovery period. Gross pathological examination revealed no evidence of organ-specific toxicity in any of the rats. Under the conditions of this study, the LC50 for the test substance was greater than 21000 ppm.