Methyl L-threoninate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Based on read across to L-TEE, L-TME is considered not to be a skin irritant.The toxicokinetic properties of L-TEE and L-TME are evaluated to be different. Read across to L-TEE is possible for endpoints in which hydrolysis of the ester bond does not take place, e.g. skin irritation and sensitisation. For endpoints in which hydrolysis takes place, thereby liberating the alcohols, i.e. methanol in the case of L-TME and ethanol in the case of L-TEE, the toxicities of the hydrolysis products must be taken into account. In general, no interaction of toxicological relevance between L-threonine and the alcohol parts is expected. Based on structural similarity and the similarity in physico-chemical properties determining skin irritation, read across to L-TEE using the analogue approach is concidered a valid approach. Further information on read across to L-TEE using the analogue approach can be found in the data matrix table attached as background material and in section 13.

Justification for type of information:

Data on target substance is not available. Thus, read-across has been applied using data from the source substance L-Threonine Ethyl Ester (L-TEE). See further read-across justification in attached background material and in section 13.

Cross-reference

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 10, 2000 - April 28, 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Minor deviations in humidity were observed during the study period but these deviations did not affect the integrity of the study.

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Version / remarks:

EC method B4

Deviations:

yes

Remarks:

humidity

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

humidity

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2500 (Acute Dermal Irritation)

Deviations:

yes

Remarks:

humidity

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: 142-576-6


STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: < 10 °C when not in use


TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Final dilution of a dissolved solid, stock liquid or gel: 50% m/v dispersion

OTHER SPECIFICS
- measurement of pH, osmolality, and precipitate in the culture medium to which the test chemical is added: pH of 9.16

Species:

rabbit

Strain:

New Zealand White

Remarks:

Crl:NZW/Kbl.BR

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Ltd, Margate
- Age at study initiation: 11 to 13 weeks old
- Weight at study initiation: 2.03 to 2,37 kg
- Housing: floor-pens, single housing
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 16 to 22 °C
- Humidity (%): 40 to 80% RH (on the first eleven days of the study, humidity fell below range by up to 15% RH)
- Air changes (per hr): 10 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours with fluorescent strip-lights

IN-LIFE DATES: From 4 April 2000 To 28 April 2000

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

water

Remarks:

moistening with approx. 0.1 mL of water

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 500mg

VEHICLE
- Amount(s) applied (volume or weight with unit): moistening with approx. 0.1 mL of water

Duration of treatment / exposure:

4 h

Observation period:

3 days

Number of animals:

3 animals (1 male, 2 females)

Details on study design:

TEST SITE
- Area of exposure: 30 x 20 mm
- % coverage: No data
- Type of wrap if used: semi-occlusive gauze patch and an open weave, elasticated adhesive bandage wrapped firmly around the torso

REMOVAL OF TEST SUBSTANCE
- Washing (if done): lightly brushed clean of any solid residues and swabbed with moist cotton wool
- Time after start of exposure: 4 hours

SCORING SYSTEM:
Erythema and eschar (Grade):
- No erythema (0)
- Very slight erythema (1)
- Well-defined erythema (2)
- Moderate erythema (3)
- Severe erythema (beet redness) or eschar preventing reading of erythema (4)

Oedema (Grade):
- No oedema (0)
- Very slight oedema (barely perceptible) (1)
- Slight oedema (edges of area well-defined by definite raising) (2)
- Moderate oedema (edges raised approximately 1 mm) (3)
- Severe oedema (raised >1 mm and extending beyond area of exposure) (4)

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Irritation parameter:

edema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Irritation parameter:

edema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Irritation parameter:

edema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Irritant / corrosive response data:

No dermal response to treatment or signs of toxicity or ill health were observed in any animal throughout the observation period

Other effects:

None

None

Interpretation of results:

GHS criteria not met

Conclusions:

The skin irritation/corrosion of L-TEE was evaluated using a single semi-occluded application to intact rabbit skin for four hours. The study was perforned in compliance with the testing guidelines OECD (404) and EC (method B4). L-TEE did not elicit any dermal reactions. Based on these data, L-TEE is not classified.

Executive summary:

This study was conducted to determine the irritation or corrosion caused to intact rabbit skin. L-TEE (500 mg) was applied to a 30 x 20 mm area on the clipped dorsum of each of three New Zealand White rabbits on Day 1. The treated area of skin was covered by a semi-occlusive bandage for four hours. Dermal reactions to treatment were assessed for three days after removal of the dressings.

No reactions were observed following a single semi-occluded, topical application of L-TEE to the intact skin of three rabbits for four hours.

Based on these data, L-TEE is not classified.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2000

Report date:

2000

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Version / remarks:

EC method B4

Deviations:

yes

Remarks:

humidity

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

humidity

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2500 (Acute Dermal Irritation)

Deviations:

yes

Remarks:

humidity

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Methyl L-threoninate

EC Number:

222-158-1

EC Name:

Methyl L-threoninate

Cas Number:

3373-59-9

Molecular formula:

C5H11NO3

IUPAC Name:

Methyl (2S,3R)-2-amino-3-hydroxy-butanoate

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): L-threonine methyl ester
- Physical state: white crystalline powder
- Analytical purity: 99.8%

Test animals

Species:

rabbit

Strain:

other: New Zealand White Crl:NZW/Kbl.BR

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Ltd, Margate
- Age at study initiation: 11 to 13 weeks old
- Weight at study initiation: 2.03 to 2,37 kg
- Housing: floor-pens
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 16 to 22 °C
- Humidity (%): 40 to 80% RH (on the first eleven days of the study, humidity fell below rge range by up to 15% RH)
- Air changes (per hr): 10 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours with fluorescent strip-lights

IN-LIFE DATES: From 4 April 2000 To 28 April 2000

Test system

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

water

Remarks:

moistening with approx. 0.1 mL of water

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 500mg

VEHICLE
- Amount(s) applied (volume or weight with unit): moistening with approx. 0.1 mL of water

Duration of treatment / exposure:

4 h

Observation period:

3 days

Number of animals:

3 animals (1 male, 2 females)

Details on study design:

TEST SITE
- Area of exposure: 30 x 20 mm
- % coverage: No data
- Type of wrap if used: open weave, elasticated adhesive bandage wrapped firmly around the torso

REMOVAL OF TEST SUBSTANCE
- Washing (if done): lightly brushed clean of any solid residues and swabbed with moist cotton wool
- Time after start of exposure: 4 hours

SCORING SYSTEM:
Erythema and eschar (Grade):
- No erythema (0)
- Very slight erythema (1)
- Well-defined erythema (2)
- Moderate erythema (3)
- Severe erythema (beet redness) or eschar preventing reading of erythema (4)

Oedema (Grade):
- No oedema (0)
- Very slight oedema (barely perceptible) (1)
- Slight oedema (edges of area well-defined by definite raising) (2)
- Moderate oedema (edges raised approximately 1 mm) (3)
- Severe oedema (raised >1 mm and extending beyond area of exposure) (4)

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Results 2

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Results 3

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Results 4

Irritation parameter:

edema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Results 5

Irritation parameter:

edema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Results 6

Irritation parameter:

edema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Irritant / corrosive response data:

No dermal response to treatment or signs of toxicity or ill health were observed in any animal throughout the observation period

Other effects:

None

Any other information on results incl. tables

The toxicokinetic properties of L-TEE and L-TME are evaluated to be different. Read across to L-TEE is possible for endpoints in which hydrolysis of the ester bond does not take place, e.g. skin irritation and sensitisation. For endpoints in which hydrolysis takes place, thereby liberating the alcohols, i.e. methanol in the case of L-TME and ethanol in the case of L-TEE, the toxicities of the hydrolysis products must be taken into account. In general, no interaction of toxicological relevance between L-threonine and the alcohol parts is expected.

L-TME holds the same structure as L-TEE except that L-TME contains a methyl alkyl-side group to the ester bond and L-TEE an ethyl alkyl-side group. Both substances are characterized by a high water solubility, a low log Pow and low vapour pressure. Hydrolysis is evaluated not to be relevant for skin irritation.

Further information on the analogue approach can be found in the data matrix attached as background material (see section below).

Applicant's summary and conclusion

Interpretation of results:

not classified

Conclusions:

The skin irritation/corrosion of L-TEE was evaluated using a single semi-occluded application to intact rabbit skin for four hours. The study was perforned in compliance with the testing guidelines OECD (404) and EC (method B4). L-TEE did not elicit any dermal reactions. Based on these data, L-TEE is not classified.

Due to the structural and physico-chemical similarity to L-TEE read cross can be made from skin irritation data on L-TEE. These data do not indicate concern for eye irritation of L-TME, hence L-TME is considered not to be a skin irritant.

Executive summary:

The skin irritation/corrosion of L-TEE was evaluated using a single semi-occluded application to intact rabbit skin for four hours. The study was perforned in compliance with the testing guidelines OECD (404) and EC (method B4). L-TEE did not elicit any dermal reactions. Based on these data, L-TEE is not classified.

L-TME holds the same structure as L-TEE except that L-TME contains a methyl alkyl-side group to the ester bond and L-TEE an ethyl alkyl-side group. The toxicokinetic profile of L-TME and L-TEE is different in terms of the alcohol part (methanol and ethanol). However, read across to L-TEE is possible for endpoints in which hydrolysis of the ester bond does not take place, e.g. skin irritation and sensitisation.

Due to the structural and physico-chemical similarity to L-TEE read cross can be made from skin irritation data on L-TEE. These data do not indicate concern for skin irritation of L-TME.