Pyridine-2-carbaldehyde

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001-08-13 to 2001-10-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Pyridine-2-carbaldehyde

EC Number:

214-333-6

EC Name:

Pyridine-2-carbaldehyde

Cas Number:

1121-60-4

Molecular formula:

C6H5NO

IUPAC Name:

pyridine-2-carbaldehyde

Test material form:

liquid

Test animals

Species:

rat

Strain:

other: Sprague-Dawley Crl:CD® (SD) IGS BR strain

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation : 8 - 12 weeks
- Weight at study initiation : male : 281-324g , female : 221-252g
- Fasting period before study : no
- Housing : The animals were housed in groups of five by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes (Datesand Ltd., Cheshire, UK) and provided with environmental enrichment aids: wooden chew blocks (B & K Universal Ltd, Grimston, Hull,UK) and cardboard “fun tunnels” (Datesand Ltd., Cheshire, UK))
- Diet : Rat and Mouse Expanded Diet No.1 (Special Diets Services Limited, Witham, Essex, UK) , ad libitum with exception of the exposure period
- Water : mains drinking water ,ad libitum with exception of the exposure period
- Acclimation period : at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C) : 21°C , +/-2°C
- Humidity (%) : 55% , +/-15%
- Air changes (per hr) : at least 15
- Photoperiod (hrs dark / hrs light) : 12/12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: Compressed air , supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus : glass concentric jet nebuliser (Radleys, Saffron Walden, Essex, UK) located at the top of the exposure chamber. The nebuliser was connected to a glass syringe attached to an infusion pump, which provided a continuous supply of test material under pressure, and to a metered compressed air supply.

- Exposure chamber volume : approximately 30l

- Method of holding animals in test chamber : Each rat was individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber and sealed by means of a rubber ‘O’ ring .

- Source and rate of air :Compressed air . Chamber air flow rates ranged from 20 to 28 L/min dependent on concentration, providing 40 to 56 air changes per hour .

- Method of conditioning air : Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters.

- System of generating particulates/aerosols : The test material was aerosolised using a glass concentric jet nebuliser (Radleys, Saffron Walden, Essex, UK)

- Method of particle size determination : The particle size of the generated atmosphere inside the exposure chamber was determined three times during each exposure period using a Marple Personal Cascade Impactor (Schaefer Instruments Ltd, Oxon., UK). This device consisted of six impactor stages (9.8, 6.0, 3.5, 1.55, 0.93 and 0.52 µm cut points) with stainless steel collection substrates and a back up glass fibre filter, housed in an aluminium sampler. The sampler was temporarily sealed in a sampling port in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through it using a vacuum pump . The collection substrates and backup filter were weighed before and after sampling and the weight of test material, collected at each stage, calculated by difference

- Treatment of exhaust air : The extract from the exposure chamber passed through a ‘scrubber’ trap and was connected with a high efficiency filter to a metered exhaust system

- Temperature, humidity, pressure in air chamber : The temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter (Hanna Instruments Ltd, Beds., UK) located in a vacant port in the animals’ breathing zone of the chamber and recorded every thirty minutes throughout the four-hour exposure period .The chamber was maintained under negative pressure.

TEST ATMOSPHERE
- Brief description of analytical method used : The actual chamber concentration was measured at regular intervals during each exposure period . The gravimetric method used employed glass fibre filters (Gelman type A/E 25 mm) placed in a filter holder. The holder was temporarily sealed in a vacant port in the exposure chamber in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through the filter using a vacuum pump . Each filter was weighed before and after sampling in order to calculate the weight of collected test material. The difference in the two weights, divided by the volume of atmosphere sampled, gave the actual chamber concentration . The nominal chamber concentration was calculated by dividing the mass of test material used by the total volume of air passed through the chamber.

- Samples taken from breathing zone: yes

VEHICLE
- Concentration of test material in vehicle : mean achieved atmosphere concentrations : 0.74 , 1.89 and 5.23 mg/l


TEST ATMOSPHERE (if not tabulated)
- Particle size distribution:
- Dose group 1 (Atmosphere concentration : 5.23 mg/l) : MMAD = 1.61 µm ; GSD = 1.51 ; Predicted amount less than 4µm = 98.6%
- Dose group 2 (Atmosphere concentration : 1.89 mg/l) : MMAD = 3.16 µm ; GSD = 1.99 ; Predicted amount less than 4µm = 63.4%
- Dose group 3 (Atmosphere concentration : 0.74 mg/l) : MMAD = 2.30 µm ; GSD = 1.99 ; Predicted amount less than 4µm = 78.8%

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

mean achieved atmosphere concentrations : 0.74 , 1.89 and 5.23 mg/l

No. of animals per sex per dose:

5 males/5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration : 14 days
- Frequency of observations and weighing : All animals were observed for clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, one hour after termination of exposure and subsequently once daily for up to fourteen days . Individual bodyweights were recorded prior to treatment on the day of exposure and on Days 7 and 14 or at death
- Necropsy of survivors performed : yes

Statistics:

Using the mortality data obtained, an estimate of the acute inhalation median lethal concentration (LC50) and 95% confidence limits of the test material were calculated using validated toxicity data analysis software (ToxCalc v5.0 (Tidepool Scientific Software, McKinleyville, Ca, USA)). The female and all-animal LC50’s were calculated by the Maximum Likelihood Regression Method (Finney, 1971) whilst the male LC50 was calculated by the Trimmed Spearman-Karber Method (Hamilton et al, 1977).

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

0.8 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: 95% confidence limit not calculable

Effect levels 2

Sex:

male

Dose descriptor:

LC50

Effect level:

2.53 mg/L air (analytical)

Based on:

test mat.

95% CL:

>= 1.65 - <= 3.87

Exp. duration:

4 h

Effect levels 3

Sex:

female

Dose descriptor:

LC50

Effect level:

0.23 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: 95% confidence limit not calculable

Mortality:

see Table 1 at "Overall remarks, attachments"

Clinical signs:

other: Signs of hunched posture, pilo-erection and red/brown staining around the snout are commonly seen in animals for short periods on removal from the chamber following 4-hour inhalation studies. Wet fur and fur stained by test material are commonly recorded

Body weight:

One male and two females showed reduced bodyweight development during Week 1 but normal bodyweight development was noted for most surviving animals during the study.

Gross pathology:

With the exception of an isolated instance of dark foci of the lungs, no macroscopic abnormalities were detected amongst surviving animals at terminal kill.
For animals that died or were humanely killed during the course of the study, the following abnormalities were detected:
Lungs – enlarged, pale, abnormally red, abnormally dark;
Liver – dark, accentuated lobular pattern;
Stomach – gaseous distension.

Applicant's summary and conclusion

Interpretation of results:

Category 2 based on GHS criteria

Conclusions:

The study was performed according to the OECD TG403 without deviations and therefore considered to be of the highest quality (reliability Klimisch 1). The validity criteria of the test system are fulfilled.
The acute inhalation median lethal concentrations (LC50) and 95% confidence limits of Pyridine-2-aldehyde in the Sprague-Dawley Crl:CD® (SD) IGS BR strain rat, were estimated to be:
All animals : 0.80 (non-calculable) mg/l
Males only : 2.53 (1.65 – 3.87) mg/l
Females only : 0.23 (non-calculable) mg/l (230 mg/m3)

An aerosol has been tested and hence, for classification the following criteria for dusts and mists are applicable:
Category 1 LC50 < 0.05 mg/L
Category 2 0.05 mg/L < LC50 = 0.5 mg/L
Category 3 0.5 mg/L < LC50 = 1.0 mg/L
Category 4 1.0 mg/L < LC50 = 5.0 mg/L

Executive summary:

The acute inhalation toxicity of the test material was investigated in rats of both sexes. The test was conducted according to OECD Guidelines for Testing of Chemicals (1981) No. 403 “Acute InhalationToxicity”. Groups of ten Sprague-Dawley Crl:CD® (SD) IGS BR strain rats (five males and five females) were exposed to an aerosol atmosphere. The animals were exposed for four hours using a nose only exposure system, followed by a fourteen day observation period. The mean achieved atmosphere concentrations and the corresponding mortalities were as follows:

Group Number	Atmosphere Concentration		Deaths
	Mean Achieved (mg/L)	Nominal (mg/L)	Male	Female	Total
1	5,23	48,0	5/5	5/5	10/10
2	1,89	17,5	1/5	4/5	5/10
3	0,74	12,0	2/5	4/5	6/10

Clinical Observations: Common abnormalities noted during the study included decreased and/or increased respiratory rate, wet fur, hunched posture and pilo-erection. There were frequent occurrences of laboured respiration, noisy respiration, red/brown staining around the snout and pallor of the extremities and several instances, particularly at the highest concentration, of corneal opacity, severe ataxia, gasping respiration and fur staining by test material. The following observations were seen sporadically: ataxia, coma, cyanosis, hypothermia, lethargy, tremors, clonic convulsions, loss of righting reflex and red/brown staining of the head. One male and two females showed reduced bodyweight development during Week 1 but normal bodyweight development was noted for most surviving animals during the study.

With the exception of an isolated instance of dark foci of the lungs, no macroscopic abnormalities were detected amongst surviving animals at terminal kill.

For animals that died or were humanely killed during the course of the study, the following abnormalities were detected :

Lungs – enlarged, pale, abnormally red, abnormally dark;

Liver – dark, accentuated lobular pattern;

Stomach – gaseous distension.

The acute inhalation median lethal concentrations (LC50) and 95% confidence limits of Pyridine-2-aldehyde in the Sprague-Dawley Crl:CD® (SD) IGS BR strain rat, were estimated to be:

All animals : 0.80 (95% confidence limit non-calculable) mg/L

Males only : 2.53 (95% confidence limit : 1.65 – 3.87) mg/L

Females only : 0.23 (95% confidence limit non-calculable) mg/L