ethynyl cyclopropane

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 March to 7 April 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Principles of method if other than guideline:

The study design was in compliance with US EPA, EEC and OECD test guidelines for acute inhalation studies .

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

425-430-1

EC Name:

-

Cas Number:

6746-94-7

Molecular formula:

C5 H6

IUPAC Name:

ethynylcyclopropane

Details on test material:

- Name of test material (as cited in study report): EthynyI cyclopropane (SD 957)
- Physical state: Colourless liquid
- Analytical purity: 97-100 %
- Lot/batch No.: 3590-129-D4
- Expiration date of the lot/batch: January 1999
- Storage condition of test material: -20°C, under nitrogen and in the dark
- Intended use: Pharmaceutical intermediate

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Limited, Manston Road, Margate, Kent, England
- Age at study initiation: four to six weeks
- Weight at study initiation: 200 to 300 g
- Fasting period before study: none
- Housing: holding cages (size 35 cm x 53 cm x 25 cm height) were made of stainless steel sheet and wire mesh; housed by sex in groups of 5
- Diet: SDS (Special Services Diet Ltd) rat diet (RM1) ad libitum
- Water: drinking water ad libitum
- Acclimation period: for a minimum period of five days prior to the start of the study


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 55 ± 15
- Air changes (per hr): 12 to 15
- Photoperiod (hrs dark / hrs light): 12/12

The batch(s) of diet used for the study was analysed for certain nutrients, possible contaminants and microorganisms.

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

EXPOSURE SYSTEM
Vapour Generator
The atmosphere generator was designed to produce and maintain an atmosphere containing vapour by evaporation of the test substance from the sintered glass disc with a countercurrent of air. All parts of the generator in contact with the test substance were made of glass. The test substance was delivered to the generator at a constant flow rate from a syringe driven by a syringe pump and the air supplied to the generator was dried, filtered and oil free.

Exposure chambers
The whole-body exposure chambers (ADG Developments ) used for the exposures were of square section (size 51cm x 51cm x 38cm height) and were made of acrylic polymer. The chambers were fitted with a pyramidal top section and had an enclosed volume of 120 liters. The rats were held for exposure in a stainless steel mesh exposure cage, subdivided to provide individual compartments for the rats. The test atmosphere entered the chamber through a port at the top centre of the chamber and was extracted at the base centre below the level of the rats. Each chamber was installed in a large fume
cupboard exhausting through an absolute filter.

PROCEDURE
A supply of clean dried air was connected to the vapour generator and the supply pressure was adjusted to give a flow rate of 25 liters per minute measured at the generator outlet tube. An in-line flow meter was used to monitor air flow throughout the exposure period. A syringe filled with the test substance was fitted to the syringe pump and connected to the generator with PTFE tubing. An initial flow rate of 0 .8 ml/min was selected for the first exposure. This flow rate was expected to give a nominal concentration of 20 mg/l in air. The flow rate of SD957 was adjusted as necessary to avoid an excessive amount of liquid on the sintered glass disc. The rats to be exposed were placed into separate compartments of the exposure chamber. The syringe pump and air supply was switched on and the exposure timed for 4 hours, following an 11 minute equilibration period. After 4 hours, the test substance was discontinued and the exposure chamber was ventilated with clean air for approximately 11 minutes to clear the test article from the chamber before the rats were removed for examination.
The procedure was repeated, for the exposure of Groups 3 and 4, using flow rates of SD957 of 0.11 and 0.018 ml/min respectively. Following exposure, the rats were returned to the holding cages and food and water supplies were restored. The test rats were kept in a ventilated cabinet overnight, separate from the control animals, and then returned to the holding room for the remainder of the observation period. The control group was treated similarly but exposed to air only for 4 hours. The control rats were returned to the holding room at the end of the exposure procedure.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

by gas chromatography

Duration of exposure:

4 h

Concentrations:

0; 0.5; 3.22; 23.3 mg/l air

No. of animals per sex per dose:

5 males, 5 females

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Other examinations performed: clinical signs, body weight, food and water consumption

Clinical signs
The rats were observed continuously for signs of reaction to the test substance during exposure and at least twice daily throughout the post-exposure period. The clinical signs were recorded at the end of the chamber equilibration period, at 0.25, 0.5 and 1.0 hours, then at hourly intervals during the exposure. During the observation period, a full clinical signs check was performed twice daily. The first check was within 1- 2 hours of the time of day of the commencement of the exposure, the second check was 6 hours later.

Bodyweight
All rats were weighed daily from the day of delivery to the Huntingdon Life Sciences until the end of the observation period.

Food and water consumption
The amount of food and water consumed by each cage of rats was measured daily from the day of arrival. The daily mean intakes of food and water for each rat were calculated from the total consumed per cage divided by the number of rats per cage giving a consumption in g/rat . Food consumption values were not adjusted for spillage.

TERMINAL STUDIES
At the end of the 14-day observation period, the rats were killed by intraperitoneal injection of phentobarbitone sodium and exsanguinated when clinically dead. All rats were subjected to a detailed macroscopic examination. The lungs were removed, with the trachea (cut below the larynx) attached, dissected clear of surrounding tissue and the trachea, bronchi and both lungs weighed in order to calculate the lung weight to bodyweight ratio. Following weighing, the lungs were infused with, and preserved in, buffered 10% formalin and ligated prior to preservation together with samples of the liver and kidneys for possible future microscopic examination.

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 22.3 mg/L air (analytical)

Exp. duration:

4 h

Effect levels 2

Sex:

male/female

Dose descriptor:

other: NOEC

Effect level:

> 0.5 - < 3.22 mg/L air (analytical)

Exp. duration:

4 h

Mortality:

There were no deaths following exposure to SD957.

Clinical signs:

other: During the exposure - During the exposure, signs seen in rats exposed to SD957 at 22.3 mg/l included unsteady movement, occasional involuntary muscular contractions, lack of response to stimuli, piloerection, partial closing of the eyes and shallow respir

Body weight:

There were no test article related effects on mean bodyweight gain following exposure to SD957.

Gross pathology:

Lung weight to bodyweight ratio
The lung weight to bodyweight ratio for test animals exposed to SD957 were similar to those of the controls.

Macroscopic pathology
One male and one female rat exposed at 22 .3 mg/l of SD957 had minimal congestion of all lobes of the lungs at post mortem. There were no other macroscopic abnormalities noted in test or control rats.

Other findings:

Food consumption
There was a slight reduction in mean food consumption for one day following exposure to SD957 at 22.3 mg/l. There were no meaningful differences between mean food consumption of SD957-exposed and control rats during the study period.

Water consumption
There were no meaningful differences between mean water consumption of SD957-exposed and control rats during the study period .

Any other information on results incl. tables

CONCLUSION

The LC50 (4-hour) for SD957 is in excess of 22.3 mg/l of air . The no effect concentration (NOEC) is in excess of 0.50 mg/l but less than 3.22 mg/l of air.