Registration Dossier

Administrative data

Endpoint:
sub-chronic toxicity: dermal
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable well-documented publication which meets basic scientific principles

Data source

Reference
Reference Type:
publication
Title:
Ultrastructural analysis of pulmonary alveolar proteinosis induced by methylnaphthalene in mice
Author:
Murata Y, Emi Y, Denda A, and Konishi Y
Year:
1992
Bibliographic source:
Exp Toxicol Pathol 44, 47-54

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Repeated-dose study employing one dose only: Primary goal of the study was to investigate by means of light and electron microscopy the ultrastructure of lesions found in the lungs of mice after induction of pulmonary alveolar proteinosis by dermal application of methylnaphthalene (mixture of 1- and 2-methylnaphthalene).
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): methylnaphthalene
- Analytical purity: no data
- Composition of test material: mixed 1- and 2-methyl isomer naphthalene preparation
(from Yamakawa Ind. Chem., Tokyo, Japan, supplied by the Ministry of Welfare of Japan)
- Isomers composition: 1- methylnaphthalene and 2-methylnaphthalene, respective portions not reported
- Stability under test conditions: considered to be stable based on inherent properties
- Storage condition of test material: no data
- Fraction in Wash oil (Composite sample No. 05): ~ 25 - 27 %

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Lab., Osaka, Japan
- Age at study initiation: no data
- Weight at study initiation: about 17 g
- Fasting period before study: no
- Housing: no data
- Diet (e.g. ad libitum): pelleted diet (MF, Oriental Yeast Ind., Tokyo, Japan); ad libitum
- Water (e.g. ad libitum): tap water; ad libitum
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- no data

Administration / exposure

Type of coverage:
open
Vehicle:
acetone
Details on exposure:
TEST SITE
- Area of exposure: back of mice
- % coverage: no data
- Time intervals for shavings or clipplings: no data

REMOVAL OF TEST SUBSTANCE: no

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): ca. 119 mg/kg bw per application
- Concentration (if solution): 1.2 % (in acetone), test solution was administered to the back skin of mice by means of a syringe
- Constant concentration used: yes

VEHICLE
- Justification for use and choice of vehicle (if other than water): no data
- Amount(s) applied (volume or weight with unit): no data
- Concentration (if solution): 1.2 % test substance in acetone

USE OF RESTRAINERS FOR PREVENTING INGESTION: no
Analytical verification of doses or concentrations:
no
Details on analytical verification of doses or concentrations:
--
Duration of treatment / exposure:
30 weeks
Frequency of treatment:
twice weekly
Doses / concentrations
Remarks:
Doses / Concentrations:
119 mg/kg bw per application (ca. 34 mg/kg bw/day)
Basis:
nominal per unit body weight
No. of animals per sex per dose:
15
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: only single dose administered

Examinations

Observations and examinations performed and frequency:
No observations or examinations are reported for the exposure period.
At the end of the study, final body weights were determined.
Sacrifice and pathology:
GROSS PATHOLOGY: at sacrifice, only lungs were removed, inspected and prepared for microscopic (light and electron microscopy) examination

HISTOPATHOLOGY: Yes; only lungs were examined.
At autopsy, the lungs were removed and fixed in 10% formaline for light microscopy.
For electron microscopy, samples of resected lung were fixed in 300 mM glutaraldehyde containing 0.1% tannic acid buffered
with 100 mM sodium cacodylate, post-fixed in 40 mM OsO4, dehydrated in ethanol, substituted with propylenoxid and embedded
in epoxy resin. Sections from paraffin blocks were stained with haematoxylin and eosin. One µm sections from epoxy resin were
stained with 0.5% toluidine blue. Ultrathin sections were doubly contrasted with 1% uranyl acetate and Reynolds' solution (2%).

Results and discussion

Results of examinations

Clinical signs:
not specified
Dermal irritation:
not specified
Mortality:
not specified
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
BODY WEIGHT AND WEIGHT GAIN
Average final body weight of mice treated with methylnaphthalene in acetone was 27.2 ± 3.2 g.
Average final body weight of control mice was 31.5 ± 1.7 g.
The average final body weight of treated animals was reduced by about 14% compared to controls.

GROSS PATHOLOGY
The lung surfaces demonstrated multiple, grayish white, soft spots or nodules sharply demarcated from the pinkish-white
surrounding normal tissues, without specific localization. No such lesions were observed in the control group.

HISTOPATHOLOGY: NON-NEOPLASTIC
The alveoli were found to be filled with amorphous eosinophilic material, many mononucleated cells with abundant foamy cytoplasm,
and many clefts corresponding to cholesterol crystals separating the intra-alveolar materials and the lining cells.
The alveolar walls were thickened but no prominent fibrosis was observed. Terminal bronchiols were not markedly affected.

Effect levels

Dose descriptor:
LOAEL
Remarks:
(30 wks, 7 d/wk)
Effect level:
34 mg/kg bw/day
Based on:
test mat.
Sex:
female
Basis for effect level:
other: Induction of pulmonary alveolar proteinosis (100% induction, only one dose tested)

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Lung was the only organ examined. Pulmonary alveolar proteinosis was found in all animals treated with methylnaphthalene (incidence 100%).

Applicant's summary and conclusion

Executive summary:

Following dermal application of methylnaphthalene (1.2 % in acetone, ca. 119 mg/kg bw per application) to the back skin of female B6C3F1 mice (group of 15 animals) twice weekly for 30 weeks, pulmonary alveolar proteinosis was induced in all of the test animals. Lung lesions were characterized by light and electron microscopy. Besides lungs, no other organs/parameters were examined.