Registration Dossier

Administrative data

Endpoint:
specific investigations: other studies
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Nasal Irritation and Pulmonary Toxicity of Aliphatic Amines in Mice
Author:
Gagnaire F., Azim S., Bonnet P., Simon P., Guenier J.P., de Ceaurriz J.
Year:
1989
Bibliographic source:
Journal of Applied Toxicology, Vol 9(5), 301-304 (1989)

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Determination of sensory irritation potency by oronasal exposure, key parameter: RD50 (RD50 = the exposure concentration resulting in a 50-% decrease in the respiratory rate).
- Principle of test:
The expiratory bradypnoea indicative of upper airway irritation was evaluated in mice during 15 minutes oronasal exposure to incresing concentraitons of the test substance. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each test compound. The test substance was as welle tested for pulmonary toxicity in mice and for the effects of a 120-min exposure on the respiratory rates of non-anaesthetized, tracheally cannulated mice (RD50TC).
- Short description of test conditions:
Upper airway irritation: the breating frequency was used as an index of upper respiratory tract irirtation. Mice were restrained in body plethysmographs for measuremnet of the respiratory rate, while the had of each animal was enclosed in the inhalation chamber. The breathing frequency was monitored with a pressure transducer (Statham 15 E) before and during a 15 minutes exposure period. For each measurement, themaximum decrease in respiratory rate was recorded. Four to six different exposure concentrations were used, and six previously unexposed mice were used at each level. For Pulmonary toxicity test: Mice were exposed via tracheal cannulation to the test substance. Mice were anaesthetized with sodium pentobarbital, given intraperitoneally (50 mg kg-1 body wt). A polyethylene cannula (Biotrol No. 5) was inserted in the trachea and secured. Animals were allowed to recover from anaesthesia for 75 min before measurement of the respiratory rate, which was monitored prior to and during a 120 minutes exposure period.
- Parameters analysed / observed: Upper airway irritation and pulmonary toxicity
GLP compliance:
not specified
Type of method:
in vivo
Endpoint addressed:
respiratory irritation

Test material

Constituent 1
Chemical structure
Reference substance name:
Isobutylamine
EC Number:
201-145-4
EC Name:
Isobutylamine
Cas Number:
78-81-9
Molecular formula:
C4H11N
IUPAC Name:
isobutylamine
Test material form:
liquid

Test animals

Species:
mouse
Strain:
other: OF1
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: IFFA Credo, Domaine des Onciens, Saint-Germain sur l'Arbresle, France
- Age at study initiation:
- Weight at study initiation: 20 - 25 g
- Fasting period before study: unfasted
- Housing: in groups of 10
- Diet., water: ad libitum
- Acclimation period: 7 d

controlled ENVIRONMENTAL CONDITIONS

Administration / exposure

Route of administration:
inhalation
Vehicle:
unchanged (no vehicle)
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION (see details below)
- Exposure apparatus: 200 L inhalation chamber
- Method of holding animals in test chamber: Mice were restrained in a body plethysmographs with nose-only exposure.



TEST ATMOSPHERE
- Brief description of analytical method used: HPLC ( sampling by silica gel in glass tubes; after derivatisation resulting m-Toluene derivatives were
analysed by reversed-phase chromatography with UV detection)
- Samples taken from breathing zone: yes
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
15 minutes oronasal exposure to determine the RD50.
120 minutes oronasal exposure to determine tthe RD50TC
Frequency of treatment:
single
Doses / concentrations
Remarks:
Several concentrations measured from 53 - 107 ppm
Basis:
analytical conc.
No. of animals per sex per dose:
6 per test concentration
Control animals:
other: internal control = each test animal before exposure
Details on study design:
Observation period: 60 min exposure, 30 min recovery, before, during and after exposure respiratory rate was determined

Results and discussion

Details on results:
Isobutylamine shows a low irritant potency for the upper airways with a measure RD50 of 91 ppm.

Applicant's summary and conclusion

Conclusions:
The authors conclude that isobutylamine like related amines mainly produce sensory upper airway irritation. Isobutylamine shows a low irritant potency for the upper airways with a measure RD50 of 91 ppm.
Executive summary:

The expiratory bradypnoea indicative of upper airway irritation was evaluated in mice during 15 minutes oronasal exposure to incresing concentrations of the test substance. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each test compound. The test substance was as well tested for pulmonary toxicity in mice and for the effects of a 120-min exposure on the respiratory rates of non-anaesthetized, tracheally cannulated mice (RD50TC).

An RD50 value of 91 ppm and a RD50TC value of 406 ppm were measured respectively. The test substance has a low irritant potency.

Previous studies with several chemicals have shown that the RD50 can be used successfully to predict safe industrial exposure. At 0.1 RD50, humans would experience some light disconfort and this should be the highest level permitted in industry. At 0.01 RD50, no sensory irritation is observed and a convenient threshold limit value (TLV) would be 0.3 RD50 (the midpoint on a logarithmic scale between the 0.1 and 0.01 RD50). The predicted safe levels to prevent upper airway irritation should not exceed 10 ppm for the test substance.

To determine RD50TC value, much higher concentrations of the test substance has to be used. According to the authors, it is not linked to the anaesthesia. The main difference between RD50 and RD50TC indicate that the test substance is mainly irritant of upper airways.

Moreover, while the respiratory rate responses of oronasally exposed mice indicative of nasal irritation set in rapidly and were reversible when exposure to the irritants ceased, the respiratory rate responses of cannulated mice were slower to develop than in oronasally exposed mice, and no, or cincomplete, revocery was observed agter the end of exposure, when mice were allowed to breath fresh air. This phenomenon might be caused by effects on the lower airways, culminating in pulmonary congestion.