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Toxicological information

Acute Toxicity: inhalation

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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:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
no
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Deviations:
no
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
Qualifier:
according to
Guideline:
EU Method B.2 (Acute Toxicity (Inhalation))
Deviations:
no
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
Qualifier:
according to
Guideline:
other: MAFF Japan Agricultural Chemicals Regulation Laws 2-1-3 Notification 12-Nousan-8147 and Notification 13 Seisan 1739 (2000 and 2001)
Deviations:
no
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
GLP compliance:
yes
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: colorless gas
Details on test material:
- Purity: 99.98%

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: approximately 8 weeks old
- Weight at study initiation: Males: between 271 and 314 grams & Females: between 184 and 225 grams
- Fasting period before study: no data
- Housing: individually in solid bottom caging with bedding and nestlets as enrichment
- Diet (e.g. ad libitum): ad libitum except during exposure
- Water (e.g. ad libitum): ad libitum except during exposure
- Acclimation period: quarantined after arrival for 6 days prior to testing.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-26ºC
- Humidity (%): 30-70%
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): artificially illuminated (fluorescent light) on an approximate 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: 19 L
- Method of holding animals in test chamber: animals were placed in a stainless steel, wire-mesh module (sexes separated) and exposed, whole-body, inside the exposure chamber
- Method of conditioning air: atmospheres were generated by dilution of test substance in air. The test substance vapour and chamber air supply were metered into a 1-liter 3-neck mixing flask by Brooks model 5850E mass flow controllers. The test substance vapour and air mixture left the flask and entered the chamber through a glass transfer tube at the top of the exposure chamber.

- Treatment of exhaust air: exhausted through a dry-ice cold trap and an MSA filter cartridge prior to discharge into the fume hood
- Temperature, humidity, pressure in air chamber: 22 ± 2°C, 50 ± 20%, no data on pressure


TEST ATMOSPHERE
- Brief description of analytical method used: the atmospheric chamber concentration of the test substance was determined by gas chromatography (GC). During the initial 4-hour exposure (mean concentration = 17000 ppm), the test substance vapour concentration was determined 16 times. The second exposure (mean concentration = 23000 ppm) was terminated after 8 minutes for humane reasons. The test substance vapour concentration was determined 3 times during the 8-minute exposure. Volumes of chamber atmosphere were continually drawn from the breathing zone of the animals and were directly injected into an Agilent model 6890 Plus gas chromatograph equipped with an automated gas sample valve and a flame-ionization detector. All samples were chromatographed isothermally at 80°C on a DB-5 (5% Phenyl Methyl Siloxane) fused silica glass column.
- Samples taken from breathing zone: yes
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Remarks on duration:
Due to humane reasons, @23000 ppm 8 min exposure max
Concentrations:
17000 ppm (for 4 hours)
23000 ppm (stopped after 8 minutes for humane reasons)
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: Animals were observed for mortality and response to alerting stimuli during each exposure and observed for mortality and clinical signs of toxicity immediately after they were removed from the exposure chamber following exposure. During a 14-day recovery period, all rats were observed each day for mortality, and were weighed and observed for clinical signs of toxicity.
- Frequency of weighing: During a 14-day recovery period, all rats were weighed.
- Necropsy of survivors performed: yes

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 17 000 ppm
Based on:
test mat.
Exp. duration:
4 h
Mortality:
No deaths occurred during the study.
Clinical signs:
Approximately 6 minutes after the 17000 ppm exposure started, the rats displayed decreased activity, which continued throughout the exposure; however, the rats’ startle responses were normal throughout the 4-hour exposure. There were no abnormal clinical signs observed in rats exposed to 17000 ppm after they were removed from the exposure chamber. There were no other clinical signs of toxicity observed in any rats in the 17000 ppm exposure group during the 14-day recovery period.

Within 2 minutes of initiating the test substance vapour flow for the 23000 ppm exposure, the rats displayed decreased activity. The rats began to display muscular spasms approximately 5 minutes into the exposure, followed by violent convulsions occurring 8 minutes into the exposure. The vapour flow was terminated 8 minutes after the exposure started for humane reasons. Within 17 minutes of when the test substance vapour was shut off, the rats displayed normal startle response and had no abnormal clinical signs of toxicity. There were no other clinical signs of toxicity observed in any other rats in the 23000 ppm exposure group throughout the entire recovery period.
Body weight:
On the day after the 17000 ppm exposure, 3 male rats displayed weight losses ranging from 1.9 to 5.7 grams and 4 of 5 female rats displayed weight losses of 2.2 to 8.4 grams. One female from the 17000 ppm exposure group continued to lose weight (6.0 grams) on post-exposure day 2. All female rats from the 17000 ppm exposure group gained weight on post-exposure day 3, but one female rat lost 6.4 grams and another lost 8.4 grams on post-exposure day 4. There were no other weight losses observed in any rats in the 17000 ppm exposure group during the 14-day recovery period.

Four of 5 female rats in the 23000 ppm exposure group lost between 5.5 and 10.1 grams on the day after the exposure. There were no other body weight losses observed in any other rats in the 23000 ppm exposure group throughout the entire recovery period.
Gross pathology:
Gross discoloration of the lungs present in two female rats in the 23000 ppm group, was nonspecific, and is a common finding in rats of this strain and age. No other gross lesions were observed.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The study and the conclusions which are drawn from it fulfil the quality criteria (validity, reliability, repeatability).
4-hour LC50 > 17000 ppm
Executive summary:

Two groups of 5 male and 5 female Crl:CD(SD) rats each were exposed whole-body to vapours of the test substance in air. Test atmospheres were generated by dilution of the test substance vapour in air. Chamber concentrations of the test substance were measured by a gas chromatograph. Rats were weighed and observed for clinical signs of toxicity during a 14-day recovery period. After the recovery period, the rats were sacrificed and examined for gross pathologic abnormalities. All animals survived the exposures and subsequent 14-day recovery period.

 

For the initial exposure, rats were exposed for 4 hours to a mean concentration of 17000 ± 250 ppm (mean ± standard deviation). Approximately 6 minutes after the exposure started, the rats displayed decreased activity, which continued throughout the exposure; however, the rats’ startle responses were normal throughout the 4-hour exposure. Three male rats displayed weight loss ranging from 1.9 to 5.7 grams on the day after the exposure. Four of 5 female rats lost weight (from 2.2 to 8.4 grams) on the day following the exposure, and one female continued to lose weight (6.0 grams) on post-exposure day 2. All female rats gained weight on post-exposure day 3, but one female rat lost 6.4 grams and another lost 8.4 grams on post-exposure day 4. There were no other weight losses or clinical signs of toxicity observed in any rats during the 14-day recovery period.

 

Based on the results of the first exposure, a design concentration of approximately 25000 ppm was set for a second exposure. Within 2 minutes of initiating the test substance vapour flow, the rats displayed decreased activity. The rats began to display muscular spasms approximately 5 minutes into the exposure, followed by violent convulsions occurring 8 minutes into the exposure. The vapour flow was terminated 8 minutes after the exposure started. The chamber concentration peaked at 25000 ppm; the mean chamber concentration for the 8-minute exposure was 23000 ppm. Within 17 minutes of when the test substance vapour was shut off, the rats displayed normal startle response and had no abnormal clinical signs of toxicity. There were no clinical signs of toxicity observed throughout the 14-day recovery period. Four of 5 female rats lost between 5.5 and 10.1 grams on the day after the exposure. There were no other body weight losses observed in any rats throughout the entire recovery period. Gross discoloration of the lungs present in two female rats in the 23000 ppm group, was nonspecific, and is a common finding in rats of this strain and age. No other gross lesions were observed.

 

Under the conditions of this study, the 4-hour LC50 for vapour atmospheres of the test substance in male and female rats was greater than 17000 ppm. An 8-minute exposure to approximately 23000 ppm caused the rats to display violent convulsions and therefore was terminated for humane reasons.