Pyridine

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Reliable with restrictions; acceptable, well-documented publication/study report based on guidelines, which meets basic scientific principles.

Data source

Reference

Reference Type:

other company data

Title:

Unnamed

Year:

1984

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

GLP compliance:

not specified

Test type:

standard acute method

Test material

Test material information

Constituent 1

Reference substance name:

Pyridine

EC Number:

203-809-9

EC Name:

Pyridine

Cas Number:

110-86-1

Molecular formula:

C5H5N

IUPAC Name:

pyridine

Details on test material:

99% purity

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

nose only

Details on inhalation exposure:

Groups of six male rats, eight weeks old and weighing between 237 and 279 g, were exposed to the test substance via inhalation (nose only exposure) at concentrations of 1600, 4900 and 6000 ppm for a single four-hour period. Surviving rats were weighed and observed daily for 14 days post exposure, weekends excluded except when deemed necessary by the rats’ condition. Except during exposure, feed and water were available ad libitum. The atmospheric concentration of the test substance was determined by gas chromatography at approximately
30-minutes intervals throughout the exposure period.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gas chromatography

Duration of exposure:

4 h

Concentrations:

1600, 4900 and 6000 ppm

No. of animals per sex per dose:

6 males per dose

Results and discussion

Effect levels

Sex:

male

Dose descriptor:

LC50

Effect level:

4 900 ppm

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Lower value of 4900 ppm is selected, equivalent to 15852 mg/m3

Mortality:

Within 4 days, 2 of 6 rats which were dosed by nose at the 4900 ppm dose group were found dead. In the group dosed with 6000 ppm, 5 of 6 rats were found dead.

Clinical signs:

other: Red nasal discharge and lack of startle response when the exposure chamber was tapped. Rats from the low dose group had labored breathing, wet perineum, hunched posture, ruffled fur and red ocular discharge. Rats from the mid (4900 ppm) dose group were

Body weight:

Severe weight loss in all dose groups on one day after exposure.

Any other information on results incl. tables

During exposure, some rats in all groups had red nasal discharge and diminished or no response when the chamber was tapped. Immediately after the four-hour exposure to 1600 ppm, rats had slightly labored breathing, wet perineum, hunched posture, ruffled fur and slight red ocular discharge. Rats exposed to 4900 ppm were limp and prostrate and had very slow and shallow breathing. Within one hour, these rats began to show signs of movement and had severely labored breathing. At 6000 ppm, five rats died during exposure. During the post-exposure observation period, one rat exposed to 4900 ppm was found dead the morning after exposure; another four days post exposure. Surviving rats in all groups had slight to severe weight loss one day post exposure. At 4900 ppm, some rats continued to lose weight for three more days. No adverse clinical signs were observed in surviving rats exposed to 1600 and 6000 ppm during the recovery period. At 4900 ppm, rats had labored breathing, red nasal, ocular and oral discharge, no righting or grasping reflexes, discolored fur and tremors. All clinical signs were absent six days post exposure.

Applicant's summary and conclusion

Interpretation of results:

Toxicity Category IV

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Pyridine was tested in a nose-only exposure protocol in a guideline acute inhalation test. The LC50 in male rats after 4 hours was 4900 ppm or 15852 mg/m3.