Propanoic acid, 2-hydroxy-, (1R,2S,5R)-5-methyl-2-(1-methylethyl)cyclohexyl ester, (2S)-

Endpoint summary

Description of key information

The substance was neither irritating to the skin nor irritating to the eyes.

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD 404

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

as of 1981

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

other: Mol:Russian

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Møllegaard Breeding Centre ApS, Ejby, Skensved, Denmark
- Age at study initiation: not reported
- Weight at study initiation: 1800 to 2700 g
- Housing: individually in PPL cages, 45 x 55 cm, with perforated floor
- Diet (e.g. ad libitum): Altromin 2123, Chr. Petersen A/S, Ringsted, Denmark ad libitum
- Water (e.g. ad libitum): fresh water ad libitum
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 55 ± 15
- Air changes (per hr): 6
- Photoperiod (hrs dark / hrs light): 12 hours darkness, 12 hours light

Type of coverage:

occlusive

Preparation of test site:

clipped

Vehicle:

other: mixture of ethanol 96% and diethylphthalate (1:1)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 mL of moistened test material
- Concentration (if solution): 50%, 10% and 1% by weight

VEHICLE
- Amount(s) applied (volume or weight with unit): 0.5 mL of test solution, i.e. test substance dissolved in a mixture of ethanol 96% and diethylpthalate (1:1)

Duration of treatment / exposure:

4 hours

Observation period:

14 days

Number of animals:

6

Details on study design:

TEST SITE
- Area of exposure: the test substance was applied to two anterior, two posterior and one centrally located site
- % coverage: not reported
- Type of wrap if used: treatment sites were covered with gauze packs that were secured with adhesive tape and fixed with Scanpore tape

REMOVAL OF TEST SUBSTANCE
- Washing (if done): skin was cleaned with soap and lukewarm water
- Time after start of exposure: 4 hours

SCORING SYSTEM:
No erythema: 0
Very slight erythema (barely perceptible): 1
Well-defined erythema: 2
Moderate to severe erythema: 3
Severe erythema (beet redness) to slight eschar formation (injury in depth): 4

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

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

other: 24, 48 and 72 hours after removal

Score:

1.33

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours after removal

Score:

0.33

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

other: 24, 48 and 72 hours after removal

Score:

1.67

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

erythema score

Basis:

animal #4

Time point:

other: 24, 48 and 72 hours after removal

Score:

1.67

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

erythema score

Basis:

animal #5

Time point:

other: 24, 48 and 72 hours after removal

Score:

1.67

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

erythema score

Basis:

animal #6

Time point:

other: 24, 48 and 72 hours after removal

Score:

1

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

edema score

Basis:

animal #1

Time point:

other: 24, 48 and 72 hours after removal

Score:

0.33

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

edema score

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours after removal

Score:

0

Max. score:

4

Irritation parameter:

edema score

Basis:

animal #3

Time point:

other: 24, 48 and 72 hours after removal

Score:

0.67

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

edema score

Basis:

animal #4

Time point:

other: 24, 48 and 72 hours after removal

Score:

0.33

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

edema score

Basis:

animal #5

Time point:

other: 24, 48 and 72 hours after removal

Score:

0.33

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

edema score

Basis:

animal #6

Time point:

other: 24, 48 and 72 hours after removal

Score:

0

Max. score:

4

Irritant / corrosive response data:

None of the animals treated with 100% showed an erythema or oedema score that would trigger classification. The scores for erythema and oedema formation were slightly higher for the test sites treated with 50% in a mixture of ethanol 96% and diethylphthalate (1:1), however, scores were not triggering classification at a test concentration of 50%. Corrosiveness to the skin was not observed. After the observation period of 14 days, few animals had sites with scattered small white scales, but the underlying skin was intact. All effects were considered to be fully reversible within 14 days.

Other effects:

No effects observed

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The substance was not irritating to the rabbit skin when tested purely or in dilution. All effects observed at observation time points at 24, 48 and 72 hours after patch removal were fully reversible within a period of 14 days.

Executive summary:

The skin irritation potential of the test substance menthyl lactate was studied under GLP in accordance with OECD TG 404. The pure substance (wetted with the vehicle ethanol 96%:diethylphthalate, 1:1) or dilutions of the test substance in the vehicle at 50%, 10% and 1% were applied for four hours under occlusion to five sites on the clipped, intact skin of six female rabbits of the stock Mol:Russian (1800 to 2700 g). After patch removal the skin was washed with soap and water. Animals were then observed for a period of 14 days and scorings of the skin were made at 24, 48 and 72 hours after patch removal. The substance or its dilutions were not corrosive to the rabbit skin. None of the individual mean scores for erythema or oedema were above 2 with the neat substance or above 2.33 with the 50% dilution. All observed effects were fully reversible within the observation period of 14 days. The substance therefore was considered to be not irritating to the rabbit skin.

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:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted under GLP-conditions in accordance with Guideline No 405.

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Version / remarks:

from February 1987

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

from January 1997

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Charles River, Deutschland GmbH, Stolzenseeweg 32-36, 88353 Kisslegg
- Age at study initiation: not reported
- Weight at study initiation: 2.8 - 3.2 kg bw
- Housing: caged individually in PPO cages (floor area: 2576 cm2) with perforated floor
- Diet (e.g. ad libitum): pelleted complete rabbit diet Altromin 2123 from Altromin, D-32791 Lage/Lippe, Germany, ad libitum
- Water (e.g. ad libitum): free access to domestic quality drinking watet acidified with hydrochloric acid to pH 2.5
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 3
- Humidity (%): 55 ± 15
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

unchanged (no vehicle)

Controls:

other: The right eye remained untreated and served as control.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 mL

Duration of treatment / exposure:

single administration; after 24 hour reading Fluorescein was instilled and treated eye was washed with 20 mL 0.9% sodium chloride solution

Observation period (in vivo):

The eyes were examined on the day before testing and 1, 24, 48 and 72 hours after the treatment.

Number of animals or in vitro replicates:

4

Details on study design:

REMOVAL OF TEST SUBSTANCE
- substance was not removed from the treated eye

SCORING SYSTEM:
see section "Any other information on materilas and methods incl. tables"

TOOL USED TO ASSESS SCORE:
Fluorescein was instilled after 24 hours, eyes were rinsed with 20 mL 0.9% sodium chloride solution and were examined using UV light

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: mean of scores at 24, 48 and 72 hours

Score:

0

Max. score:

4

Irritation parameter:

iris score

Basis:

mean

Time point:

other: mean of scores at 24, 48 and 72 hours

Score:

0

Max. score:

2

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

other: mean of scores at 24, 48 and 72 hours

Score:

0.3

Max. score:

3

Reversibility:

fully reversible within: 48 hours

Irritation parameter:

chemosis score

Basis:

mean

Time point:

other: mean of scores at 24, 48 and 72 hours

Score:

0

Max. score:

4

Irritant / corrosive response data:

One hour after application of the test article all animals showed a diffuse crimson red conjunctiva with individual vessels not easily discernible and some swelling above normal. After 24 hours all animals showed some conjunctival vessels definitely injected. After 48 and 72 hours all animals were free of any signs of eye irritation.

Other effects:

No other effects were reported.

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The substance is non irritating to the rabbit eye.

Executive summary:

The potential for eye irritation was tested for methyl acetate in a GLP study according to OECD guideline No. 405. Four female albino rabbits weighing 2.8 to 3.2 kg were used in the study. The day before testing both eyes of the animals were examined before and after the instillation of Fluorescein to ensure there were no defects or irritation. The next day an aliquot of 0.1 mL of the neat substance was placed in the left eyes of the animals by gently pulling the lower lid away from the eyeball. The lids were then gently hold together for one second. The right eye remained untreated and served as control. The eyes were examined and the grade of ocular reaction was recorded 1 and 24 hours later. After a first reading at 24 hours, Fluorescein was instilled and the treated eye was rinsed with 20 mL 0.9 % sodium chloride solution. Then the eye was examined again using UV-light to detect possible corneal damage. Further gradings were done after 48 and 72 hours after treatment. One hour after application of the test article all animals showed a diffuse crimson red conjunctiva with individual vessels not easily discernible and some swelling above normal. After 24 hours all animals showed some conjunctival vessels definitely injected. After 48 and 72 hours all animals were free of any signs of eye irritation. On the basis of these observations it was concluded that the substance is non-irritating to the rabbit eye.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

- skin irritation / corrosion

In the key study, the pure substance was applied for four hours under occlusion to five sites in the clipped, intact skin of six female rabbits of the stock Mol:Russian. The substance was not corrosive to the rabbit skin. None of the individual mean scores (24, 48 and 72 hours after removal) of erythema or oedema were above 2. All observed effects were fully reversible within the observation period of 14 days. The substance therefore was considered to be not irritating to the rabbit skin (Skydsgaard 1990).

In a non-guideline and non-GLP supporting study 50 % solution of the test substance in olive oil was applied daily for 5 days to the shaved skin flanks of 12 guinea pigs. No skin reactions were observed after this treatment, which is in line with the key study result (Hopf 1976).

- eye irritation

50 % of menthyl lactate diluted in olive oil was not irritating in the eyes of 8 tested rabbits. The study was not performed under GLP conditions and not according to OECD or EU guidelines.

The read across substance menthyl acetate was not irritating in rabbit eyes.

Menthyl lactate was investigated in the Hen's Egg Test - Chorioallantoic Membrane (HET-CAM). A 50 % solution of the test substance in diethylphthalate applied to the vital, vascularised chorionallantois membrane produced clear signs of irritation including vascular injection, hemorrhage, lysis and coagulation. Since the HET-CAM test is still not validated and the method evaluation report of ICCVAM from 2006 demonstrates that the chemical class of alcohols could lead in 88% to false positive test results it is likely that the menthyl lactate result in HET-CAM was a false positive result too, especially taking the no response in rabbit eyes and the "no skin reactions" into account.

Justification for selection of skin irritation / corrosion endpoint:
The key in vivo study is valid and reliable. The substance is not irritating or corrosive to skin.

Justification for selection of eye irritation endpoint:
Menthyl lactate administered to rabbit eyes according to the method of Draize was not irritating (reliable 3). The read across substance Menthyl acetate was not irritating in rabbit eyes (reliability 1).

Justification for classification or non-classification

- skin irritation/corrosion:

Based on the above stated assessment of the irritating properties of menthyl lactate, the results from reliable in vivo studies show that the substance is not irritating to the skin. Accordingly the test item does not need to be classified according to Council Directive 2001/59/EC (28th ATP of Directive 67/548/EEC) and according to CLP (Regulation (EC) No 1272/2008 of the European Parliament and of the Council) as implementation of UN-GHS in the EU.

- eye irritation / corrosion:

Based on the above stated assessment of the irritating properties of menthyl lactate, the results from the in vivo study and the valid study with read across substance menthyl acetated show that the substance is not irritating to the eye. Accordingly the test item does not need to be classified according to Council Directive 2001/59/EC (28th ATP of Directive 67/548/EEC) and according to CLP (Regulation (EC) No 1272/2008 of the European Parliament and of the Council) as implementation of UN-GHS in the EU.