1-butylpyrrolidin-2-one

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental starting date:2017-02-08 - 2017-02-28 (gross necropsy) - 2017-04-28 (Issue of Final report)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

The initial target exposure level was slightly greater than the regulatory limit study concentration of 5 mg/L for aerosols (approximately 5.2 mg/L). Since there was no mortality observed at the limit test, additional exposure levels were not required.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

traditional method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1-butylpyrrolidin-2-one

EC Number:

222-437-8

EC Name:

1-butylpyrrolidin-2-one

Cas Number:

3470-98-2

Molecular formula:

C8H15NO

IUPAC Name:

1-butylpyrrolidin-2-one

Test material form:

liquid

Details on test material:

Physical Description: clear, colorless liquid
Storage Conditions: Kept in a controlled temperature area set to maintain 18 °C to 24 °C, capped with nitrogen

Test animals

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animal Receipt and Acclimation
The Crl:CD(SD) rats used for this study were received in good health from Charles River Raleigh on 07 Feb 2017. Each animal was inspected by a qualified technician upon receipt. The rats were uniquely identified by ear tags displaying the animal numbers and were acclimated to the laboratory for a minimum of 6 days. During the acclimation period, the rats were observed twice daily for mortality and moribundity. The animals were subjected to restraint in the nose only exposure holding tubes for 1 hour on 13 Feb 2017 prior to test substance exposure. Following the restraint period, each animal was observed and there were no clinical signs of injury or stress. Animals were held in restraint tubes for 20 minutes prior to initiation of exposure after they were delivered to the exposure room.

Animal Housing
Upon arrival, all animals were housed individually in suspended wire-mesh cages. Caging was cleaned at appropriate intervals. The animals were maintained in accordance with Charles River Ashland SOPs and the Guide for the Care and Use of Laboratory Animals (National Research Council, 2011). On the day of exposure, the animals were placed in nose only exposure holding tubes in the animal room, transported to the exposure room, exposed for the requisite duration, and then returned to their home cages.

Diet, Drinking Water, and Maintenance
The basal diet used in this study, PMI Nutrition International, LLC, Certified Rodent LabDiet® 5002 (block), is a certified feed with appropriate analyses performed by the manufacturer and provided to Charles River Ashland. Reverse osmosis-treated water supplying the facility is analyzed for contaminants according to Charles River Ashland SOPs. Filters servicing the automatic watering system are changed regularly according to Charles River Ashland SOPs. The results of the diet and water analyses are retained with the Charles River Ashland facility data. No contaminants were present in animal feed or water at concentrations sufficient to interfere with the objectives of this study. The basal diet and reverse osmosis-treated water, delivered by an automatic watering system, were provided ad libitum, except during acclimation to the nose only restraint and during the exposure period. Water bottles were provided as appropriate following exposure.

Environmental Conditions
The animal room was maintained with controlled temperature, humidity, and fluorescent lighting (12 hours light/12 hours dark). The light status (on or off) was recorded once every 15 minutes. The room temperature and humidity controls were set to maintain conditions of 73°F ± 5°F (approximately 23°C ± 3°C) and 50% ± 20% relative humidity. Room temperature and relative humidity were monitored continuously using the Metasys DDC Electronic Environmental control system and were scheduled for data collection on an hourly basis. Actual mean daily temperature ranged from 72.5°F to 73.2°F (22.5°C to 22.9°C) and mean daily relative humidity ranged from 40.9% to 48.0% during the study. Air handling units were set to provide a minimum of 10 fresh air changes per hour, 100% fresh air.

Enrichment
Each animal was provided devices for environmental enrichment and to aid in maintaining the animals’ oral health (starting during acclimation). Enrichment devices were not available during the restraint acclimation and the exposure period and were sanitized approximately weekly. Additional enrichment was provided following acclimation to nose only exposure restraint tubes.

Assignment of Animals to Treatment Groups
Animals used in the study were selected from available stock and were arbitrarily assigned to an exposure group based on age and body weight requirements and on the appearance of general good health. The selected animals were approximately 8 weeks old at initiation of exposure; body weight values ranged from 261 g to 272 g for males and from 200 g to 207 g for females. Individual body weights at assignment were within ca. 20% of the mean for each sex.

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

2.4 µm

Geometric standard deviation (GSD):

1.67

Remark on MMAD/GSD:

N = 2

Details on inhalation exposure:

Temperature (°C): 22
Standard Deviation: 0.5
Relative Humidity (%): 23
Standard Deviation: 2.6
Airflow Rate (LPM): 33.5
Standard Deviation: 0.30
N = 4
In order to achieve the target concentration, additional humidified air was not added to the exposure system, resulting in a relative humidity for the test substance atmosphere which was less than the protocol-specified minimum of 30%. Low humidity for a liquid aerosol atmosphere is considered acceptable for a single 4-hour exposure and does not adversely affect the results or interpretation of the data.

Nominal Exposure Concentration:
Test substance used: 48.2 g; Exposure Time: 240 min; Nominal Concentraiton 6.0 mg/L)
Actual Exposure Concentration:
Target concentration: 5.2 mg/L, Mean actual concentration: 5.1 mg/L, Standard Deviation: 0.22, N = 8

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

5.1 mg/L

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: observed for mortality twice daily, observed for clinical signs once during exposure, after the 4-hour exposure, 1 - 2 hours post exposure and once daily for 14 days following exposure, body weight were obtained on Study Days 0, 1, 3, 7, and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.1 mg/L air (nominal)

Mortality:

None of the animals died during exposure or during the 14-day post-exposure observation period.

Clinical signs:

other: The only clinical observation noted during exposure was labored respiration for 1 female. Clinical observations following exposure consisted of ataxia (this incidence was reduced at the next observation period and was not observed thereafter), prostration

Body weight:

All animals lost weight from Study Day 0 to Study Day 1 (5 g to 29 g). All animals surpassed their initial (Study Day 0) body weight by Study Day 14 and were considered normal.

Gross pathology:

The only macroscopic finding noted at the scheduled necropsy was clear fluid content in the uterus for 1 female.

Any other information on results incl. tables

Text Table 8
Clinical Observations following Exposure
Clinical Observation	Group (mg/L) 5.1
	M	F
Ataxia	5	2
Prostration	0	3
Hypoactivity	1	0
Clonic Convulsions	0	2
Body Cool to Touch	0	2
Labored Respiration	0	1
Decreased Respiration	3	4
Partial Closure Left Eye	1	3
Partial Closure Right Eye	1	3
Wet Red Material Around Nose	1	1

Text Table 9
Clinical Observations 1-2 Hours Post-Exposure
Clinical Observation	Group (mg/L) 5.1
	M	F
Ataxia	3	1
Unkempt Appearance	1	0
Hypoactivity	0	1
Impaired Equilibrium	0	2
Prostration	0	3
Labored Respiration	0	1
Partial Closure Left Eye	1	3
Partial Closure Right Eye	1	3
Dried Red Material Around Nose	1	0

Text Table 10
Clinical Observations during the 14-Day Post-Exposure Period
Clinical Observation	Group (mg/L) 5.1
	M	F
Unkempt Appearance	0/0	2/2
Defecation Decreased	1/1	3/3
Urination Decreased	0/0	1/1
Small Feces	0/0	2/1
Dried Clear Material Ventral Neck	0/0	2/2
Dried Clear Material Ventral Trunk	0/0	3/3
Dried Clear Material Urogenital Area	0/0	1/1
Wet Yellow Material Urogenital Area	0/0	1/1
Dried Red Material Around Nose	0/0	2/2

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The LC50 of the test substance was > 5.1 mg/L when male and female Crl:CD(SD) rats were exposed to an aerosol of the test substance as a single, 4-hour, nose only exposure.

Executive summary:

The objective of this study was to determine the acute inhalation toxicity of the test substance when administered as a single, 4-hour, nose only inhalation exposure to rats. The protocol was designed in accordance with the US EPA OPPTS Guideline 870.1300, Acute Inhalation Toxicity, August, 1998 and the OECD Guidelines for the Testing of Chemicals, Section 403, Acute Inhalation Toxicity, September, 2009. The test substance was administered to 1 group of 5 male and 5 female Crl:CD(SD) rats via nose only inhalation exposure as a liquid droplet aerosol at a concentration of 5.1 mg/L. The aerosol exposure atmosphere was characterized by a mean particle size of 2.4 ± 1.67 μm (MMAD ± GSD). Mortality, clinical observations, body weights, and body weight changes were evaluated over a 14-day post-exposure observation period. Necropsies were conducted on all animals.

None of the animals died during the study. The only clinical observation noted during exposure was labored respiration for 1 female. Clinical observations following exposure consisted of ataxia, prostration, hypoactivity, clonic convulsions, body cool to touch, laboured and decreased respiration, partial closure of the eye(s), and red material around nose. Clinical observations at the 1 to 2 hour post-exposure observation period consisted of ataxia, hypoactivity, unkempt appearance, impaired equilibrium, prostration, labored respiration, partial closure of the eye(s), and red material around nose.

Clinical observations during the 14-day post-exposure observation period consisted of unkempt appearance, defecation and urination decreased, small feces, red material around nose, yellow material urogenital area, and clear material neck, trunk, and urogenital area. All animals were considered clinically normal by Study Day 4. All animals lost weight from Study Day 0 to Study Day 1. All animals surpassed their initial (Study Day 0) body weight by Study Day 14. The only macroscopic finding noted at the scheduled necropsy was clear fluid content in the uterus for 1 female.

Based on the results of this study, the LC50 of the test substance was > 5.1 mg/L when male and female Crl:CD(SD) rats were exposed to an aerosol of the test substance as a single, 4-hour, nose only exposure.