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Acute Toxicity: inhalation

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acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
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 Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 403 (Acute Inhalation Toxicity)
The study was conducted according to the guideline in effect at the time of study conduct.
GLP compliance:
Test type:
standard acute method
Limit test:

Test material

Details on test material:
- Purity: 99.7%

Test animals

other: Crl:CD®BR
Details on test animals and environmental conditions:
- Age at study initiation: Young adult
- Weight at study initiation: 218-299 g
- Fasting period before study: No
- Housing: Individual suspended wire-mesh cages
- Diet (e.g. ad libitum): ad libitum, except during exposures
- Water (e.g. ad libitum): ad libitum, except during exposures
- Acclimation period: Minimum of 7 days

- Temperature (°C): 21.7-22.5°C
- Humidity (%): 27.8-71.5% (protocol specified 30-70%)
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours dark

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Details on inhalation exposure:
- Exposure apparatus: Exposures were conducted in either 110 L glass and acrylic (4880 ppm) or a 500 L (10800 and 19400 ppm) glass and stainless steel whole-body exposure chambers.
- Exposure chamber volume: 110 L or 500 L
- Method of holding animals in test chamber: Animals were caged individually during the exposures.
- Source and rate of air: Vaporization air from laboratory compressed air system
- Method of conditioning air: Not reported
- System of generating particulates/aerosols: Vapour atmospheres were generated using one of two generators. Generator A (used for 4880 ppm exposures) consisted of a 500 mL three-necked flask, containing the test material, maintained at a constant elevated temperature (approximately 33°C) in a water bath. Vapourization air was supplied to one of the necks of the flask, a thermometer was in the second neck, and the test vapour exited through the remaining neck of the flask. The vapour-laden air was diluted via a T-connection with humidified compressed air and was introduced directly into the 110 L chamber. Generator B (used for 10800 and 19400 ppm exposures) consisted of a vaporization column made from glass pipe which was filled with glass beads of varying size. Near the top of the column, liquid test material was added via a metering pump. All of the chamber ventilation air, from the laboratory supply air system, was passed through the vapourization column from the bottom to the top. The test atmosphere was then transported via glass pipe to the top of the 500 L chamber.
- Method of particle size determination: Not reported
- Treatment of exhaust air: Not reported
- Temperature, humidity, pressure in air chamber: 17-23°C, 37-61%, pressure not reported, and oxygen content was 20.2-21.0%

- Brief description of analytical method used: A continuous sample of test atmosphere was drawn through an infrared gas analyzer. Analog output from the instrument was displayed on a chart recorder and expressed as chartlines.
- Samples taken from breathing zone: Yes
Analytical verification of test atmosphere concentrations:
Duration of exposure:
4 h
Nominal Concentrations: 5000, 10000, and 20000 ppm
Analytical Concentrations: 4880, 10800, and 19400 ppm (50307, 111335, and 199991 mg/m3 , respectively)
No. of animals per sex per dose:
5 males and 5 females per dose
Control animals:
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: Rats were observed for mortality and clinical signs during the exposure and approximately 1-hour post-exposure on day 0 and twice daily thereafter for 14 days.
- Frequency of weighing: Immediately prior to exposure on day 0 and on study days 7 and 14
- Necropsy of survivors performed: yes
The LC50 was calculated by the method of Litchfield and Wilcoxon.

Results and discussion

Effect levels
Dose descriptor:
Effect level:
114 428 other: mg/m3 (11100 ppm)
95% CL:
97 129 - 128 750
Exp. duration:
4 h
Remarks on result:
other: Adverse Effects: mortality (2/5 male and 2/5 female inter.; 5/5 male and 5/5 female high); concentration- related intermittent convulsions (all groups).
All animals exposed to 19400 ppm died within 50 minutes of exposure initiation. The exposure was terminated at that time. Two male and 2 female rats exposed to 10800 ppm died on Day 0.
Clinical signs:
other: At 4880 ppm, ataxia (5 males and 5 females), hyperactivity (2 males, 1 female), and intermittent convulsions (1 male, 3 females) were observed during exposure. At 10800 ppm, hyperactivity (1 male), intermittent convulsions (5 males, 5 females), prostra
Body weight:
No remarkable body weight changes were observed for surviving animals.
Gross pathology:
At 4880 ppm, 1 female exhibited dark red area(s) of lungs at scheduled sacrifice.

At 10800 ppm, findings in animals that died during exposure included mottled lungs (1 male), dark red lungs (1 female), and red matting-external surface (2 males, 2 females). Findings in animals that survived to scheduled necropsy included dilated pelvis of kidney (1 male), dark red lungs (1 male), and hair loss-external surface (1 female).

At 19400 ppm, findings for animals that died during exposure included dark red area(s) of lungs (2 males), dark red lungs (2 males, 2 females), dark red contents of stomach (1 male), hemorrhagic thymus gland (2 males), clear matting-external surface (1 male, 5 females), and red matting-external surface (3 males).

Applicant's summary and conclusion

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

LD50 = 11100 ppm (114428 mg/m3)
Executive summary:

The acute inhalation toxicity of the test substance was evaluated in a 4-hour single exposure study in rats. The test substance was administered via whole-body exposure as a vapour at concentrations of 4880 (50307 mg/m3), 10800 (111335 mg/m3), and 19400 ppm (199991 mg/m3). Following the exposure, surviving animals were maintained for a 14-day observation period. Parameters evaluated included mortality, clinical observations, body weights, and gross necropsy.


None of the rats died at 4880 ppm. All of the rats died during exposure at 19400 ppm and 4 rats died during exposure to 10800 ppm. The only concentration dependent clinical observations were the incidence of intermittent convulsions at all concentrations. Other clinical signs of toxicity occurred in a non-dose (concentration)-related manner. T hese included findings such as ataxia (4800 ppm), hyperactivity (4880 and 10800 ppm), and prostration (10800 and 19400 ppm). Other less significant signs included extremities pale in colour, salivation, various observations of wet red material around the mouth, nose, neck and forelimbs, and clear nasal discharge. At the 1-hour post-observation, dried red material on the forelimbs, nose and mouth were noted as well as isolated observations of hyperactivity, vocalization upon handling and various areas with wet/dry yellow or brown matting and/or material. All surviving animals appeared normal by day 3 and for the remainder of the study, except 1 female who had scabbing and persistent hair loss of the ventral neck. There were no remarkable body weight changes. Nearly all of the animals that died during exposure had clear or red matting on the external body surface. Five animals exhibited dark red lungs, 2 animals had dark red area(s) on the lungs and one had mottled lungs. Other findings included 1 animal with dark red stomach contents, and 2 with hemorrhagic thymus gland. Of the animals that were terminally euthanized, 1 animal each was noted as having dilated pelvis of the kidney, dark red lungs, dark red areas of the lungs, and external surface hair loss. Based on the data obtained, the LC50was found to be 11100 ppm (114428 mg/m3) with 95% confidence limit of 9900 to 12500 ppm when male and female rats were exposed to the material as a vapour for a single, 4-hour period.