Homosalate

Endpoint summary

Description of key information

NOAEL subacute oral study with homosalate: 300 mg/kg bw/day
NOAEL (for homosalate) from subchronic oral study with read-across substance methyl salicylate: 86 mg/kg bw/day
NOAEC (for homosalate) from subacute inhalation study with read-across substance methyl salicylate: 1207 mg/m³

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

no data are available

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This is an old study (1963), 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.

Reason / purpose for cross-reference:

reference to same study

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

Species:

rat

Strain:

Osborne-Mendel

Sex:

male/female

Details on test animals or test system 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

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:

once daily

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

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

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.

Dose descriptor:

NOAEL

Effect level:

50 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: for methyl salicylate

Dose descriptor:

NOAEL

Effect level:

86 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: read-across value for homosalate

Critical effects observed:

not specified

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.

Conclusions:

Under the test conditions, growth retardation and bone lesions were reported at 1.0 and 2.0% and gross pituitary lesions at 0.5% MeS in the diet. Based on this study, the NOAEL /oral/rat is 50 mg/kg body weight/day for methyl salicylate. This corresponds to 86 mg/kg bw/day of homosalate.

Executive summary:

Webb and Hansen (1963) administered methyl salicylate in the diet to groups of male and female Osborne-Mendel rats at 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 bw/day for two years. All rats in the 1000 mg/kg group died by the 49th week. Body weight of both sexes was significantly decreased in the 500 and 1000 mg/kg 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. The relative testis weight of males was 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 increased at 250 but not 500 mg/kg bw/day compared to controls.

Based on this study, the NOAEL value is 50 mg/kg body weight/day.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

86 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

A chronic study with the read-across substance methyl salicylate and a subacute study with homosalate gave consistent results

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Single concentration tested. No data on substance purity.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

GLP compliance:

no

Species:

rat

Strain:

other: Alderley Park

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Alderley Park
- Age at study initiation: no data
- Weight at study initiation: mean 200g
- Fasting period before study: no data
- Housing: no data
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: no data

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Not applicable, vapour

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

7 hours per day, 5 days per week

Remarks:

Doses / Concentrations:
700 mg/m3
Basis:
nominal conc.

No. of animals per sex per dose:

4

Details on study design:

not given

Positive control:

no data

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: Daily

FOOD CONSUMPTION: - No data

FOOD EFFICIENCY:- No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: No data
- Time schedule for collection of blood: No data
- Animals fasted: No data
- How many animals: No data

CLINICAL CHEMISTRY: No data

URINALYSIS: Yes
- Time schedule for collection of urine: Overnight after last exposure
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data

NEUROBEHAVIOURAL EXAMINATION: No data

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Other examinations:

none

Statistics:

no data

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Dose descriptor:

NOAEC

Effect level:

700 mg/m³ air (nominal)

Basis for effect level:

other: overall effects, no adverse effects. Values for methyl salicylate.

Dose descriptor:

NOAEC

Effect level:

1 207 mg/L air (nominal)

Basis for effect level:

other: read-across value for homosalate

Critical effects observed:

not specified

No toxic signs and no macroscopic or microscopic effects were seen at necropsy following exposure to a saturated atmosphere for 7 hours per day, 5 days per week for 4 weeks.

Conclusions:

Methyl salicylate showed no evidence of toxicity by inhalation when tested at an effectively saturated concentration for 7 hours per day for four weeks. The highest tested concentration of methyl salicylate of 700 mg/m³ corresponds to 1207 mg/m³ of homosalate.

Executive summary:

4 female Alderley Park rats weighing an average of 200 g were exposed to a dynamic atmosphere (atmosphere continuously generated and passed through the exposure chamber) containing a saturated atmosphere (700 mg/m3) of methyl salicylate for 7 hours per day, 5 days per week for 4 weeks. Food and water were available ad libitum. Animals were weighed each day, and their condition and behaviour were recorded throughout the exposure period. Urine was collected overnight after the last exposure day for biochemical testing. Gross necropsy was conducted as well as microscopic examination of organs. Methyl salicylate at 700 mg/m3 (120 ppm), the maximum achievable atmosphere, did not cause any adverse effects (Gage, 1970).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

1 207 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

A suitable read-across study is available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Study duration:

subacute

Species:

rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

WoE was done based on the 28-day part of an oral OECD 422 study with homosalate and a chronic oral study with the read-across substance methyl salicylate. The two studies gave consistent results with NOAELs of 300 and 86 mg/kg bw/day, respectively. A read-across justification is provided as attachment to IUCLID section 13 respectively as appendix to the CSR

.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
WoE was done based on 28-day part of OECD 422 with homosalate and a chronic oral study with the read-across substance methyl salicylate

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
A 28-day repeated inhalation toxicity study is available with the read-across substance methyl salicylate

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
A 28-day repeated inhalation toxicity study is available with the read-across substance methyl salicylate

Justification for classification or non-classification

In a subacute study with homosalate, no severe toxic effects were observed at 300 mg/kg bw/day (which was the NOAEL in this study) and in a subchronic study with the read-across substance methyl salicylate, the NOAEL was 86 mg/kg bw/day (expressed as homosalate), while at a 5-fold higher dose histopathologic alterations of the pituitary and bone marrow without functional effects were observed. Based on these data, no classification and labelling according to the CLP (Regulation EC No 1272/2008) Specific target Organ Toxicity Repeat Exposure (STOT RE) or according to the DSD (Directive 67/548/EEC) is required.