Ethyl 2-methylbutyrate

Endpoint summary

Description of key information

The skin and eye irritation studies undertaken indicate that this substance is not classified for these endpoints.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 May to 6 June 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: OECD 402

GLP compliance:

yes (incl. QA statement)

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Ltd, Margate, Kent
- Age at study initiation: approximately 8 to 12 weeks old
- Weight at study initiation: males weighed 222 to 231g, and the females 215 to 226g
- Fasting period before study: No details provided in report
- Housing: The animals were housed in suspended polypropylene cages furnished with woodflakes. The animals were housed individually during the 24-hour exposure period and in groups of five, by sex, for the remainder of the study.
- Diet (e.g. ad libitum): Free access to mains drinking water and food (Rat and Mouse Expanded Diet No.1, Special Diets Services Limited, Witham, Essex, UK) was allowed throughout the study.
- Water (e.g. ad libitum): Free access to mains drinking water and food (Rat and Mouse Expanded Diet No.1, Special Diets Services Limited, Witham, Essex, UK) was allowed throughout the study.
- Acclimation period: minimum acclimatisation period of five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25
- Humidity (%): 30 to 70
(Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study).
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12 hours continuous light and 12 hours darkness

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

TEST SITE
- The calculated volume of the test material, as received, was applied uniformly to an area of shorn skin (approximating to 10% of the total body surface area) using a graduated syringe. A piece of surgical gauze was placed over the treatment area and semi-occluded with a piece of self-adhesive bandage. The animals were caged individually for the 24-hour exposure period. Shortly after dosing the dressings were examined to ensure that they were securely in place.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): The bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened with distilled water to remove any residual test material. The animals were returned to group housing for the remainder of the study period.
- Time after start of exposure: After the 24-hour contact period

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): Dose volume 2.33 ml/kg and Specific gravity 0.861 (Dose level 2000 mg/kg)

Duration of treatment / exposure:

24 hours

Observation period:

14 days

Number of animals:

5/sex/group

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for 14 days. Individual bodyweights were recorded prior to application of the test material on Day 0 and on Days 7 and 14.
- Necropsy of survivors performed: At the end of the study the animals were killed by cervical dislocation and subjected to gross pathological examination. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.
- Other examinations performed: After removal of the dressings and subsequently once daily for 14 days, the test sites were examined for evidence of primary irritation and scored according to the following scale from Draize J H (1977) “Dermal and Eye Toxicity Tests” In: Principles and Procedures for Evaluating the Toxicity of Household Substances, National Academy of Sciences, Washington DC p.31 (see attached report for details). Any other skin reactions, if present were also recorded.

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

There was no evidence of skin irritation in any animal at any timepoints. Mean scores: eythema 0, oedema 0, other skin effects 0.

Interpretation of results:

not irritating

Remarks:

Migrated information

Conclusions:

Based on the results of an acute dermal toxicity study in male and female rats at 2000 mg/kg EMB is considered not to be irritating to skin.

Executive summary:

A group of ten rats (five males and five females) was given a single 24-hour, semi-occluded dermal application to intact skin at a dose level of 2000 mg/kg body weight. The animals were observed for fourteen days after the day of treatment and were then killed for gross pathological examination.

 There were no deaths. No signs of systemic toxicity or dermal irritation were noted during the study.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 May to 16 May 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

other: SPF Albino rabbits of stock Chbb:HM (SPF) – Littlerussian

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: BI Pharma KG, 88397 Biberach
- Age at study initiation: No details provided in report
- Weight at study initiation: 1.9 - 2.1 kg bw
- Housing: During a pre-period of at least one week and throughout the experiment the rabbits were caged individually in PPO cages (floor area: 2576 sq.cm) with perforated floor.
- Diet (e.g. ad libitum): A pelleted complete rabbit diet “Altroimin 2123” from Altromin, D-32791 Lage, Lippe, was available ad libiturn. Analyses for major nutritive components and relevant possible contaminants are performed regularly on the diet. Certificates of analysis are retained.
- Water (e.g. ad libitum): The animals had free access to bottles with domestic quality drinking water acidified with hydrochloric acid to pH 2.5 in order to prevent microbial growth. Analyses for relevant possible contaminants are performed regularly. Certificates of analysis are retained.

ENVIRONMENTAL CONDITIONS
The study took place in animal room No. 6 provided with filtered air at the following conditions:
- Temperature (°C): 20 ± 3
- Humidity (%): 55 ± 15
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 hours light and 12 hours darkness. Light was on from 6 am to 6 pm

Vehicle:

not specified

Controls:

other: The untreated right eye

Amount / concentration applied:

0.1 ml

Duration of treatment / exposure:

24 hours

Observation period (in vivo):

7 days

Number of animals or in vitro replicates:

4 female (The study was initiated with one rabbit. Since no marked eye irritation was seen in this animal another three rabbits were included in the study with time difference).

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): The eyes were examined and the grade of ocular reaction was recorded one hour and 24 hours later. After the first 24 hour reading Fluorescein was instilled. After rinsing with 20 ml 0.9% sodium chloride solution the eyes were examined again using UV-light to detect possible corneal damage.
- Time after start of exposure: 24 hours

SCORING SYSTEM: See attached report for details

TOOL USED TO ASSESS SCORE: The day before testing both eyes of the animals were examined with a hand held inspection lamp fitted with white and UV light and magnifying glass with, 2 x magnification to ensure there were no defects or irritation. The examination was performed before and after instillation of Fluorescein.

The eyes were examined and the grade of ocular reaction was recorded one hour and 24 hours later. After the first 24 hour reading Fluorescein was instilled. After rinsing with 20 ml 0.9% sodium chloride solution the eyes were examined again using UV-light to detect possible corneal damage.

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Reversibility:

fully reversible within: 7 days

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Reversibility:

fully reversible within: 7 days

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

1.1

Reversibility:

fully reversible within: 7 days

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0.8

Reversibility:

fully reversible within: 7 days

See Table 1 of attached report for individual results.

- One hour after application of the test article animals No. 1770 and No. 1773 showed a diffuse, crimson red conjunctiva with individual vessels not easily discernible, an obvious swelling with partial eversion of lids and a discharge with moistening of the lids and hairs just adjacent to lids in animals No. 1771 and No. 1772 were observed a diffuse, crimson red conjunctiva with individual vessels not easily discernible, an obvious swelling with partial eversion of lids and a discharge different from normal.

 

- 24 hours after application of the test article animals No. 1770 and No. 1772 showed some conjunctival vessels definitely injected and a swelling above normal. In animal No. 1771 were observed a diffuse, crimson red conjunctiva with individual vessels not easily discernible as well as an obvious swelling with partial eversion of lids. Animal No. 1773 showed a diffuse, crimson red conjunctiva with individual vessels not easily discernible as well as a swelling above normal.

 

- 48 hours after application of the test article in animals No. 1770 and No. 1771 were observed some conjunctival vessels definitely injected and a swelling above normal. Animals No 1772 and No. 1773 showed some conjunctival vessels definitely injected.

 

- 72 hours after application of the test article in animals No. 1770 and No. 1773 were observed some conjunctival vessels definitely. Animal No. 1771 showed some conjunctival vessels definitely injected and a swelling above normal. In animal No. 1772 was observed a conjunctival swelling above normal.

 

- 7 days after application of the test article all four animals were free of any signs of eye irritation.

 

The following mean values were obtained from the data presented in Table 1 of attached report:

 

cornea opacity         0.0

iris lesion                  0.0

redness of conjunctiva   1.1

oedema of conjunctiva (chemosis) 0.8

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

According to the directive of the EEC commission 93/21/EEC of May 4, 1993 ETHYL METHYLBUTYRATE-2, Batch No 20010036, shall not be classified as eye irritating.

Executive summary:

The local effect of ETHYL METHYLBUTYRATE-2 was investigated according to the method recommended in the OECD Guideline No. 405, “Acute Eye Irritation/Corrosion”, Feb. 1987, and EEC Guideline B.5 “Acute Toxicity (Eye irritation)”, Jan. 1997.

Four female albino rabbits were exposed to 0.1 ml of the test article in the left eye. The eyes were examined and the changes were graded according to a numerical scale one hour, 24, 48 and 72 hours as well as 7 days after dosing.

 

Slight to well-defined signs of irritation were observed on the treated eyes. All effects were fully reversible within 7 days.

 

The following mean values, based on the results from the 24, 48 and 72 hour readings, were calculated:

 

Animal No. Cornea opacity Iris lesion Redness of conjunctiva Oedema of conjunctiva

1770 0.00 0.00 1.00 0.67

1771 0.00 0.00 1.33 1.33

1772 0.00 0.00 0.67 0.67

1773 0.00 0.00 1.33 0.33

 

According to the directive of the EEC commission 93/21/EEC of May 4, 1993 ETHYL METHYLBUTYRATE-2, Batch No. 20010036, shall not be classified as eye irritating.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Justification for selection of skin irritation / corrosion endpoint:
No specific skin irritation study is available. However, an acute toxicity study by the dermal route (Sanders 2000b) does not indicate skin irritation up to the limit dose level (2000 mg/kg).

Justification for selection of eye irritation endpoint:
Only Key Study

Justification for classification or non-classification

The skin and eye irritation studies undertaken indicate that this substance is not classified for these endpoints.