Registration Dossier

Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Does not meet important criteria of today standard method. Incomplete histopathology. Only one dose tested. Atmosphere analyzed gravimetrically only.

Data source

Reference
Reference Type:
publication
Title:
Retinopathy from inhaling 4,4'-methylenedianiline aerosols
Author:
Leong BKJ, Lund JE, Groehn JA, Coombs JK, Sabaitis CP, Weaver RJ & Griffin RL
Year:
1987
Bibliographic source:
Fund.Appl.Toxicol. 9: 645-58

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Guinea pigs were exposed for 2 weeks to MDA aerosols.
Following a 2 week incubation period, each animal was tested for dermal irritation, dermal sensitization (0.05ml 2, 20, 200 mg MDA/ml PEG) followed by tests for pulmonary sensitization in tracheostomized animals (200 mgMDA/ml PEG). 
The animals were then killed, and histopathologically examined (only few organs were investigated, no histopathology on the upper respiratory tract).
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Methylene dianiline (MDA) containing 94.6 % 4,4'-MDA, 2.1 % of 2,4-MDA, plus small percentages of trimers and monoformamide;

Test animals

Species:
guinea pig
Strain:
other: albino Hartley and pigmented guinea pigs of mixed variety
Sex:
male
Details on test animals and environmental conditions:
The animals, of body weight 350-539 g, were exposed nose-only.  
After each exposure the exposed animals were housed individually in regular caging facilities with a 12 hr light/dark cycle, and were provided with food and water ad libitum. The control animals were housed in regular cages throughout the experimental period. After the 2 weeks of exposure the exposed animals were kept for a 2-week "incubation" period.  

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
other: polyethylene glycol 200 (PEG)
Remarks on MMAD:
MMAD / GSD: The average aerosol particle size was 2.4 micrometers as determined by light scattering.
Details on inhalation exposure:
The test atmosphere was generated by atomizing a solution of 200 mg MDA/ml polyethylene glycol 200 into an air elutriator.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Air samples were taken thgough preweighed glass filters (1l/min for 5 min). The quantity of MDA-PEG was determined gravimetrically. The actual quantity was calculated with the density of the solution.
The aerosol particle size distribution was monitored using a light scattering particle size analyser.
Duration of treatment / exposure:
10exposures in 14 days
Frequency of treatment:
4 hours/day; 5 days/week
Doses / concentrations
Remarks:
Doses / Concentrations:
0.44 mg/l
Basis:
other: time-weighted average aerosol concentration
No. of animals per sex per dose:
8
Control animals:
yes, concurrent no treatment
Details on study design:
Post-exposure period: 14 days

Examinations

Observations and examinations performed and frequency:
Irritation assay:
Observations for erythema and edema were performed 1, 2, 3, 4, and 24h postapplication and graded according to the Draize procedure.

Pulmonary sensitization assay:
Measurement of the lung insufflation pressures (LIP) following aerosol application of 10 and 50 µl (200mg MDA/ml PEG) to tracheostomized and cannulated animals.

Histopathology:
eyes, lungs, liver, kidney, spleen

Results and discussion

Effect levels

Dose descriptor:
LOAEL
Effect level:
0.44 other: mg/l
Sex:
male

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

During exposures no overt respiratory distress was observed.

Ten 4hr-exposures to 0.44 mg/ml MDA aerosol produced no visible symptoms in guinea pigs (albino and pigmented).

Even after challenge by dermal application of a solution of MDA in polyethylene glycol (2, 20 or 200 mg/ml) 2 weeks following the last inhalation application no symptoms were detected.

Likewise challenge with an MDA-PEG aerosol (200 mg/ml) did not result in changes in lung insufflation pressure of tracheostomized guinea pigs.

There was slight body weight loss during the exposure days, and recovery during the 2 resting weekend days. It was said that this might have been due to stress

rather than exposure to MDA, since the trends in body weight gain for the entire

experimental period were comparable between the exposed and control animals. 

The most prominent histopathological findings were degeneration of the inner and

outer segments of the photoreceptor cells and the pigmented epithelial cell layer of the retina in both kinds of guinea pig.


7/16 exposed animals had pulmonary granulomas against 1/8 control animals. The
granulomas were small and consisted of an aggregate of macrophages surrounded

by a think mantle of lymphocytes. MDA particles were not evident.  
3/16 exposed animals had a slight to mild granulomatous pneumonitis, as had 1/8
control animals which had received a challenge dose of MDA-PEG aerosol during the pulmonary sensitization test. There were no histological changes in liver or

kidneys related to MDA-PEG treatments.

Applicant's summary and conclusion