Acetonitrile

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Acetonitrile

EC Number:

200-835-2

EC Name:

Acetonitrile

Cas Number:

75-05-8

Molecular formula:

C2H3N

IUPAC Name:

acetonitrile

Details on test material:

- Name of test material (as cited in study report): Acetonitrile HPLC Grade
- Physical state: Clear liquid
- Analytical purity: 99.9%
- Impurities (identity and concentrations): Water: 0.002%
- Lot/batch No.: 973432
- Storage condition of test material: Room temperature
- Supplier: Fisher Chemicals, Fair Lawn, New Jersey

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acetonitrile HPLC Grade
- Physical state: Clear liquid
- Analytical purity: 99.9%
- Impurities (identity and concentrations): Water: 0.002%
- Lot/batch No.: 973432
- Storage condition of test material: Room temperature
- Supplier: Fisher Chemicals, Fair Lawn, New Jersey

Test animals

Species:

mouse

Strain:

other: Crl:CD-1® (ICR) BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

Individually identified by unique ear tag.

TEST ANIMALS
- Source: Charles River Laboratories, Portage, MI
- Age at study initiation: 6-9 weeks
- Weight at study initiation: 27-37g (m); 21-27g (f)
- Housing: Animals were individually housed in stainless-steel wire mesh cages.
- Diet: Certified Rodent Chow #5002, PMI Feeds Inc., St. Louis, Missouri available ad libitum, except during the exposures.
- Water: Available ad libitum, except during the exposures.
- Acclimation period: 7 - 20 days

ENVIRONMENTAL CONDITIONS
- Temperature: 64-74°C
- Humidity: 37-57%
- Photoperiod: 12 hrs dark/12 hrs light

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

Test article was delivered from a Fluid Metering Incorporated (FMI) pump, equipped with a 1/8 inch pump head through 1/8 inch Teflon tubing at a constant rate to a glass chromatography column containing glass beads. Compressed air, metered by a flowmeter at approximately 0.21-0.32 (Group 1), 0.40 (Group 2), 0.32(Group 3) or 0.28 (Group 4) mL/min flowed counter current, vaporizing the test article. The test article vapor passed through a condensation trap prior to being introduced into the chamber through a turret inlet.

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Stainless steel and glass whole-body exposure chamber
- Exposure chamber volume: 160 liter
- Source and rate of air: Minimum chamber air flow rate of 32 L/min resulting in 12 air changes/hour.
- Temperature, humidity, pressure in air chamber: The chamber was maintained to the maximum extent possible at a temperature between 20 to 24degrees C and a relative humidity between 40 to 60%. Chamber temperature, percent relative humidity, and air flow rate were monitored continuously and recorded at 30 minute interval during the exposure period.

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: A single particle size distribution was performed once during each exposure using a cascade impactor to determine the mass median aerodynamic diameter and geometric standard deviation of any aerosol present. After completion of the last animal exposure, the presence of any aerosols was re-evaluated using a Sibata, Model P-5H, light scattering digital dust indicator at the high concentration level (5000 ppm). The P-5H was placed in line, downstream from the generation system, between the aerosol trap and chamber inlet (refer to Figure 2). In this design, all of the generated test atmosphere passed through the P-5H before entering the exposure chamber. Output from the P-5H was recorded with a strip chart recorder. Light scattering readings were recorded during a 20 minute control period, a 30 minute test period, and a 20 minute recovery period.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

continuously by infrared spectrometry

Duration of exposure:

4 h

Concentrations:

3202, 5499, 4653, 3747 ppm (nominal); 3039, 5000, 4218, 3568 ppm (analytical).

No. of animals per sex per dose:

4 groups of 5 males and 5 females.

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days during which all animals were observed once daily for clinical signs. The examination included, but was not limited to, observations of the general condition, skin, fur, eyes, ears, nose, oral cavity, thorax, abdomen, external genitalia, limbs and feet, as well as evaluation of respiration and palpation (post-exposure) of tissue masses.
- Necropsy of survivors performed: yes, Euthanasia of animals surviving to study termination was by intraperitoneal injection of sodium pentobarbital anesthesia. The trachea was exposed ad clamped such that the lungs were removed and examined in an inflated state. All major organ systems in the thoracic and abdominal cavities were observed for gross abnormalities by a veterinary pathologist. No tissues were preserved.
- Other examinations performed: All animals were observed at least twice a day for morbidity, mortality, injury, and availability of food and water. The use of a computerized data collection system (Xybion) required observations and body weights to be defined in such a manner that day 1 was the day of exposure and days 2-15 were post-exposure days 1-14. Body weights were recorded just prior to the exposure, on days 8 and 15 (post-exposure days 7 and 14), and when an animal was found dead.

Statistics:

The concentration mortality data were statistically analyzed for the LC50 and its confidence limits by the method of Bliss, CI (1938), The determination of the dosage-mortality curve from small numbers. Quarterly Journal of Pharmacy and Pharmacology, 11: 192-216.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

3 587 ppm

95% CL:

> 2 938 - < 4 039

Exp. duration:

4 h

Mortality:

Combined sex mortalities were 20, 80, 90, and 50% for Groups 1- 4, respectively. Male mortality was slightly greater than the female mortality in each exposure group. All mortalities occurred on the day of exposure, except for a single Group 1 male that died on post-exposure day 1 (study day 2).

Clinical signs:

other: Clinical signs observed during the exposure and up to 4 hours post-exposure included death, decreased activity, abnormal gait, loss of righting reflex, slow respiration, labored breathing, rapid respiration, gasping, cold to touch, limbs splayed, leaning

Body weight:

Surviving animal body weights from Groups 1 and 3, and the Group 4 males remained at pre-exposure levels during the post-exposure observation period. Of the 2 surviving females from Group 2, 1 gained weight and 1 remained at the pre-exposure level during the first post-exposure week, but both lost weight (1 or 2 grams) during the second post-exposure week. Three of the surviving 4 Group 4 females gained weight during the post-exposure period. The remaining Group 4 female lost weight (1 gram) during the first post-exposure week and regained its pre-exposure weight by the end of the second post-exposure week.

Gross pathology:

At necropsy, no test article-related macroscopic findings were observed in male or female mice.

Applicant's summary and conclusion

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Based on the results of this study, the 4-hour LC50 of Acetonitrile (HPLC Grade) in mice (via whole-body exposure) was calculated to be 3587 ppm, with 95% confidence limits of 2938-4039 ppm. Acetonitrile has a harmonised classification of Acute Tox 4 H332.

Executive summary:

In a guideline (OECD 403 equivalent) and GLP study, the 4-hour vapor LC50 of Acetonitrile (HPLC Grade) in mice (via whole-body exposure) was calculated to be 3587 ppm (6022 mg/m3), with 95% confidence limits of 2938-4039 ppm (4933 - 6781 mg/m3). Clinical signs observed during the exposure and up to 4 hours post-exposure included death, decreased activity, abnormal gait, loss of righting reflex, slow respiration, labored breathing, rapid respiration, gasping, cold to touch, limbs splayed, leaning to the right, and yellow body surface staining. Surviving animals from Groups 2-4 (5000, 4218, and 3568 ppm) were judged normal by study day 2. Clinical signs observed during the 14-day observation period for Group 1 (3039 ppm) included death, decreased activity, and decreased defecation. Group 1 survivors were judged normal by study day 5.