Registration Dossier

Administrative data

Endpoint:
short-term repeated dose toxicity: dermal
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Only limited information given.
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
The physiological response of rabbits to cyclohexane, methylcyclohexane, and certain derivatives of these compounds. I Oral Administration and Cutaneous Administration
Author:
Treon, J. et al.
Year:
1943
Bibliographic source:
J. Indust. Hygiene Toxicol. 25(6), 199-214

Materials and methods

Principles of method if other than guideline:
Subacute (6-day) dermal toxicity study in one rabbit
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): methylcyclohexane
- Substance type: pure substance
- Physical state: colourless liquid
- Analytical purity: 97%
- Impurities (identity and concentrations): toluene, 3%
- Specific gravity: 0.767

Test animals

Species:
rabbit
Strain:
other: White
Sex:
not specified
Details on test animals and environmental conditions:
TEST ANIMALS
- Weight at study initiation: ca. 3.185 kg (calculated from the reported results)

Administration / exposure

Type of coverage:
open
Vehicle:
unchanged (no vehicle)
Details on exposure:
TEST SITE
- Area of exposure: approx. 24 square inches (corresponding to ca. 155 cm²) of the anterior abdominal wall
- Time intervals for shavings or clipplings: the hair of the animal was closely clipped prior to the first application.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): the test material was removed by washing with soap and water.
- Time after start of exposure: 1 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 60 mL (twelve 5 mL portions at 5 min intervals)
- Constant volume or concentration used: yes

USE OF RESTRAINERS FOR PREVENTING INHALATION: yes
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
6 days
Frequency of treatment:
daily, 12 applications within 1 h
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
60 mL per 24 square inches per day (specific gravity 0.767)
Basis:
other: reported data
Remarks:
Doses / Concentrations:
ca. 300 mg/cm²/day
Basis:
nominal per unit area
Remarks:
Doses / Concentrations:
ca. 14450 mg/kg bw/day
Basis:
nominal per unit body weight
No. of animals per sex per dose:
1 animal
Control animals:
no

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DERMAL IRRITATION: Yes
- Time schedule for examinations: daily

BODY WEIGHT: Yes
- Time schedule for examinations: presumably daily (not specified)

RECTAL TEMPERATURE: Yes
- Time schedule for examinations: presumably daily (not specified)

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
slight hypothermia, no mortality
Dermal irritation:
effects observed, treatment-related
Description (incidence and severity):
local irritation, skin hardening, thickening and ulceration
Mortality:
mortality observed, treatment-related
Description (incidence):
slight hypothermia, no mortality
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
slight loss in weight
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:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY
The treated animal did not die and slight hypothermia (not further specified) was observed during the 6-day study period.

DERMAL IRRITATION
Repeated application of methylcyclohexane to the skin of a rabbit induced local irritation and thickening. The irritation appeared on the second day and increased with succesive treatments. Hardening of the skin, thickening and ulceration appeared later and the experiment was terminated after the 6th day.

BODY WEIGHT AND WEIGHT GAIN
The treated animal showed a slight loss in weight (not further specified) during the 6 day-study period. The loss in body weight was regained within 2 days.

Effect levels

open allclose all
Dose descriptor:
conc. level:
Effect level:
300 mg/cm² per day (nominal)
Based on:
test mat.
Sex:
not specified
Dose descriptor:
dose level:
Effect level:
14 450 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
not specified
Basis for effect level:
other: succesively increasing local irritation; hardening of the skin, thickening and ulceration appearing within 6 days; slight hypothermia and loss in weight

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

The authors reported the "range of lethal dosage" to be > 86.7 g/kg bw.

This is evidently a cumulated dose calculated over the 6 -day study period:

60 mL per day = 46.02 g per day (based on a specific gravity of 0.767)

46.02 g x 6 days = 276.12 g

A cumulated dose of 86.7 g/kg bw is thus calculated assuming a body weight of ca. 3.185 kg.

Applicant's summary and conclusion

Conclusions:
Methylcyclohexane was applied to the clipped skin of one rabbit in twelve 5 ml portions at 5 min intervals within 1 h, after which the material was removed by washing with soap and water. This uncovered skin procedure was done on 6 consecutive days. Based on the reported total amount of test substance applied daily (60 mL), the specific gravity (0.767) and the animal body weight (3.185 kg), the applied dose was roughly equivalent to 14450 mg/kg bw/day. The test substance was applied on a surface of approximately 24 square inches (corresponding to ca. 155 cm²). Thus, the local dose was about 300 mg/cm²/day.
Slight hypothermia and a slight loss in body weight (no further details given) were observed in the treated animal during the 6-day study period. The loss in body weight was regained within 2 days. Repeated application of methylcyclohexane to the skin of a rabbit induced local irritation and thickening. The irritation appeared on the second day and increased with successive treatments. Hardening of the skin, thickening and ulceration appeared later and the experiment was terminated after the 6th day.

Due to deficiencies in study design (one animal, one dose level, 6-day exposure) and limited documentation, the results of this study are not fully sufficient for assessment of toxicity after repeated dermal exposure, not adequate for the purpose of classification and therefore inconclusive.

CLP: inconclusive
DSD: inconclusive