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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
no data are available
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This is an old study predating GLP however the protocol and results were reported in adequate detail and included hematological studies, gross pathology, and limited histopathological examinations of key organs and tissues.
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Chronic and subacute toxicology and pathology of methyl salicylate in dogs, rats, and rabbits
Author:
Webb WK, Hansen WH
Year:
1963
Bibliographic source:
Toxicol Appl Pharmacol 5: 576-687

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
MeS was blended with diet and administered daily for a period of 2 years.
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: Methyl Salicylate
- Molecular formula: C8H8O3
- Substance type: oily liquid
- Analytical purity: 99%
- Impurities (identity and concentrations):no data
- Composition of test material, percentage of components: no data
- Purity test date: no data
- Lot/batch No.: no data
- Expiration date of the lot/batch: no data
- Stability under test conditions: no data
- Storage condition of test material: no data
- Other: methyl salicylate was colorless, had a specific gravity of 1.17 and had the odor of wintergreen

Test animals

Species:
rat
Strain:
Osborne-Mendel
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: no data
- Age at study initiation: weanling
- Weight at study initiation: ~ 50 g
- Fasting period before study: no data
- Housing: no data
- Diet: ad libitum
- Water: no data
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod: no data


IN-LIFE DATES: no data

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:


DIET PREPARATION
- Rate of preparation of diet (frequency): every other week
- Mixing appropriate amounts with (Type of food): no data
- Storage temperature of food: all diets were stored in sealed cans under refrigeration
- Other: 10% additional methyl salicylate was added at time of mixing to compensate for evaporation

VEHICLE: none
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
none
Duration of treatment / exposure:
2 years
Frequency of treatment:
daily
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 0.1, 0.5, 1 and 2% (0, 50, 250, 500, and 1000 mg/kg bw/day)
Basis:
nominal in diet
No. of animals per sex per dose:
25/sex/dose (except for 24 males, 26 females in 2% group)
Control animals:
yes
Details on study design:
- Dose selection rationale: the data reported in the subchronic study in rats by the same authors (methyl salicylate/ dietary administration for 17 weeks in rats).

Positive control:
no data are available

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: No


DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: The rats were weighed weekly.


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): No


FOOD EFFICIENCY: No



OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 3, 11, 17 and 22 months.
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes
- How many animals: 10 rats/dose



CLINICAL CHEMISTRY: No


URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Other examinations:
none
Statistics:
not reported

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
effects observed, treatment-related
Details on results:
CLINICAL SIGNS AND MORTALITY
Animals of the 1.0% and 2.0% groups developed rough hair coats. In the high-dose group, half of the animals died by week 8 and all of the animals
died by week 49 of the study.
BODY WEIGHT AND WEIGHT GAIN:
Animals of the 1.0% and 2.0% groups had statistically significant growth inhibition.
HAEMATOLOGY
no hematological effects were observed.ORGAN WEIGHTSAverage organ weights were similar for all animals. however, relative organ to body weight
ratios for the testes of male animals and for the heart and kidneys of the female animals of the 1.0% groups were significantly increased.
GROSS PATHOLOGY
gross lesions of the pituitary gland were observed in 10 animals of the 0.5% group as compared to four animals in the control
group.In the 2% group, 29 of the 50 animals had pneumonia, which appeared to be more acute than regularly observed.
HISTOPATHOLOGY: NON-NEOPLASTIC
Microscopically, the only induced lesion was a pronounced change in the bones of the rats on the 2.0% diet.
Cancellous bone in the metaphysis was increased as compared to same-age controls; this was observed to a moderate degree in five and a marked
degree in four of the nine bones examined from animals of the 2.0% group. Bone lesions were slight in 2 of 11 and 1 of 11 bones examined from
animals of the 1.0% and 0.5% groups, respectively. The affected bones had fewer osteoclasts, and the number was inversely proportional to the
degree of change.
HISTOPATHOLOGY: NEOPLASTIC
The data are limited:Malignant pituitary tumors occurred in 1 male and 2 female rats on the 0.5% diet. Mammary tumors occurred in females rats on
all diets.

Effect levels

Dose descriptor:
NOAEL
Effect level:
50 mg/kg diet
Sex:
male/female
Basis for effect level:
other: Increased amount of cancellous bone from 250 mg/kg

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

The results for a supplemental study:

One male test animal died on day 11, the two others died on day 19. The females died on days 31, 40 and 71. Rough hair coat and growth inhibition was observed for all test animals, with some animals having labored respiration.

Grossly, four of the six treated rats had slight to moderate lung damage. Focal gastric hemorrhages were present in the glandular portion of three of the test animals. Bone growth was affected.

Long bones of the limbs showed reduced length and diameter compared to controls. Density of the hypophysis of long bones was increased.

Applicant's summary and conclusion

Conclusions:
Under the test conditions, growth retardation and bone lesions were reported in rats at levels of 1.0 and 2.0% MeS in the diet, with minimal effects at 0.5%. Based on this study and the subchronic oral study, the NOAEL /oral/rat is 0.1% (50 mg/kg body weight/day, equivalent to 59.2 mg/kg ASA ).
Executive summary:

Webb and Hansen (1963) administered methyl salicylate in the diet to groups of 24 -25 male and 25 -26 female Osborne-Mendel rats at dietary concentrations of 0, 0.1%, 0.5%, 1.0% or 2.0% in the diet providing doses of approximately 0, 50, 250, 500, and 1000 mg/kg body weight/day for two years. All rats in the 1000 mg/kg group died by the 49th week. Body weight of both sexes were significantly decreased in both the 500 and 1000 mg/kg group body weight/day groups.

An increased amount of cancellous bone was present in the metaphyses in rats treated at either 500 or 1000 mg/kg body weight/day, with a more marked effect at the highest dose level. A slight increase was reported in one rat at 250 mg/kg. The relative testes weights of males were significantly increased as were the relative weights of the heart and kidneys of females in the 500 mg/kg body weight/day group. Gross pituitary gland lesions were found in 10 rats at 250mg/kg bw/day compared to four animals in the control groups. while based on chronic and subchronic oral studies in rat by Webb and Hansen (1963), the NOAEL value is 50 mg/kg body weight/day (equivalent to 45.4 mg/kg bw/day as SA or 59.2 mg/kg ASA).