Registration Dossier

Administrative data

Endpoint:
respiratory sensitisation: in vivo
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP compliant study, no restrictions, fully adequate for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Investigation of the sensitising potential upon inhalation exposure. The methods and procedures used were essentially based on methods described in Arts et al. (1998).
(Arts JHE, Kuper CF, Spoor SM, Bloksma N (1998) Airway morphology and function of rats following dermal sensitization and respiratory challenge with low molecular weight chemicals. Toxicol Appl Pharmacol 152: 66-76).
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
NOCOLOK flux is a white powder and has the following characteristics:
Name of test material: NOCOLOK flux
Chemical name: AlKI4
Batch number: 4B010701
Purity: 99%
Expiry date: 1 January 2004
Storage conditions: room temperature

Test animals

Species:
rat
Strain:
Brown Norway
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Wiga GmbH, Sulzfeld, Germany
- Age at study initiation: about 10 weeks
- Housing: 3/cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 12 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.8
- Humidity (%): 61
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Test system

Route of induction exposure:
inhalation
Route of challenge exposure:
inhalation
Vehicle:
unchanged (no vehicle)
Concentration:
100 mg/m3
No. of animals per dose:
6
Details on study design:
The airway sensitisating potential of an aerosol of NOCOLOK flux was studied in Brown Norway (BN) rats. One group of 6 female rats was exposed to a target concentration of 100 mg/m3 NOCOLOK flux for six hours a day for 5 consecutive days (sensitisation phase). Approximately 14 days later these animals were exposed to the same concentration of NOCOLOK flux for 30 min (challenge phase; group B). Two control groups, also of 6 female BN rats each, were used. One group was sensitised only (group C), the other group was exposed to air during the sensitisation phase and challenged to 100 mg/m3 NOCOLOK flux for 30 min approximately 14 days later.
The day after challenge hyperresponsiveness to methacholine was tested in all animals; two days after challenge the animals were necropsied. To examine possible allergenicity of NOCOLOK flux, total and specific IgE levels, breathing pattern and frequency during challenge, hyperresponsiveness to methacholine one day after challenge, and histopathology of the respiratory tract and bronchoalveolar lavage fluid measurements two days after challenge were carried out. To examine the toxicity of the test material clinical signs, body weights, and organ weights were recorded.

The mean actual concentration (+/- standard deviation) of NOCOLOK flux in the test atmosphere during the sensitisation phase was 104.4 (6.7) mg/m3. During challenge the mean concentration was 100.3 (1.2) mg/m3. The mean MMAD (Mass Median Aerodynamic Diameter) of the particles in the aerosol was 2.5 µm with a mean geometric standard deviation of 1.7.

Results and discussion

Results:
The absence of increases in specific IgE levels, the absence of changes in breathing frequency and pattern during challenge, and the absence of changes in hyperresponsiveness to methacholine in all groups, and the absence of changes in bronchoalveolar lavage parameters and histopathology between the test group and sensitised only animals, suggest that the test substance is not a respiratory sensitiser. The concentration tested, i.e. 100 mg/m3 for both sensitisation as well as challenge, was considered high enough in view of the observed histopathological and bronchoalveolar lavage fluid changes.

Any other information on results incl. tables

No treatment-related abnormalities were observed.

 

No treatment-related changes in body weight gain were noted.

 

A statistically significant increase in total serum IgE levels was noted in sensitized rats. Measurement of specific serum IgE levels, was, however, negative.

 

Visual examination of the recordings of the breathing pattern during the sensitisation phase of animals of group A (challenge only control group) and group B (test group) did not reveal exposure-related changes. Measurement of breathing frequency in animals of these groups during challenge revealed a slight decrease in breathing frequency during exposure and within one hour after exposure, and a slight increase 48 hours after exposure, which were, however, not different among the two groups. There were no obvious changes in breathing pattern between animals of these groups, except for an apnoeic breathing pattern in one animal of group B.

 

No treatment-related changes in cholinergic hyperresponsiveness upon methacholine challenge 24hafter challenge were observed.

 

No treatment-related changes in organ weights were observed.

 

Macroscopic examination at necropsy revealed enlarged mediastinal and parathymic lymph nodes in one sensitised animal that may be related to repeated exposure to the test compound.

 

Repeated (5-day) inhalation of NOCOLOK flux in BN rats (sensitised animals; groups B and C) induced histopathological changes in the nasal passages, larynx, and lungs. Focal olfactory epithelial degeneration, necrosis and regeneration were observed in the nasal passages. In the larynx, there was a focal granulomatous inflammation. In the lungs, alveolar bronchiolisation and typical alveolar macrophage accumulations were seen. In the animals exposed singly to NOCOLOK flux (challenge only animals; group A), a minimal granulocytic and lymphocytic/monocytic inflammatory cell infiltrate only was seen in the larynx of a few animals.

In addition, the pulmonary granulomatous inflammation, which is characteristic for (untreated) BN rats, was found in the single exposed animals (group A). In group B and C animals, this granulomatous inflammation was less prominent, and the cell infiltrate surrounding the terminal bronchioli had changed from a granulocytic into a predominantly lymphocytic or mixed granulocytic/lymphocytic infiltrate.

 

Animals of groups B and C exhibited a significantly increased percentage of neutrophils and a significantly decreased percentage ofeosinophils in bronchoalveolar lavage fluid, which was reflected in a significantly higher absolute number of neutrophils in animals of group B only. In animals of group C both the absolute and relative number of lymphocytes was significantly lower than those of the other two groups. Statistically significantly increased levels of y-glutamyl transferase (GGT) and lactate dehydrogenase (LDH) were observed in bronchoalveolar lavage fluid of animals of groups B and C when compared to animals of group A.

Applicant's summary and conclusion