Ethyl (S)-2-hydroxypropionate

Endpoint summary

Description of key information

The potential of ethyl (S)-lactate to induce skin corrosion/irritation and eye irritation was tested in vivo and in vitro. Based on the results, ethyl (S)-lactate must be considered as not irritating to the skin but damaging to eyes. According to Annex VI of CLP Regulation 1272/2008, ethyl (S)-lactate is classified as Eye Dam. 1, H318 and STOT SE 3 (H335).

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:

1995-06-19 to 1995-07-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

adopted 17th July 1992

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material used in the report: ethyllactate
- CAS No.: 687-47-8
- Trade name: Purasolv EL
- Batch No.: 950122
- Appearance: clear, colourless liquid
- Purity: 98%
- Storage: ambient

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: SPF bred New Zealand White albino rabbits were obtained from the Broekmans Institue, Someren, the Netherlands
- Age at study initiation: males, young adult
- Weight at study initiation: 2130-2220 g
- Housing: individually in stainless steel cages, fitted with perforated floor
- Diet (e.g. ad libitum): standard laboratory rabbit diet, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: 6/7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 3
- Humidity (%): 52.5-75
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

An amount of 0.5 mL of the test substance was distributed over a patch measuring 2.5 x 2.5 cm.

Duration of treatment / exposure:

4 hours

Observation period:

14 days

Number of animals:

3

Details on study design:

Three or four days prior to the start of the study, the hair was removed from the back and flanks of the animals using electric clippers in a way as to avoid abrasions. One day prior to application of the test material, the skin site was inspected for hair growth and the clipping was repeated. Just prior to application, a skin site suitable for application was selected on the clipped back and flanks of the animal. An amount of 0.5 mL of the test substance was distributed over a patch measuring 2.5 x 2.5 cm. The patch loaded with the test substance was fixed tot the selected application site by means of adhesive tape. Subsequently, the entire trunk of the rabbit was wrapped with self-adhesive-gauze to maintain the patch in position and to retard evaporation of volatile substances. The gauze was additionally fastened with two stripes of tape. After a 4-hour exposure period, the test substance and patch were removed, and the test site was cleaned with a moistened tissue. Circa 1 hour later, the resulting skin reactions were evaluated by the method of Draize et al. (J. Pharmacol. Exp. Ther. 82 (1944) 377-390). Further skin readings were made at approximately 24, 48 and 72 hours, and at 7 and 14 days after treatment.

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

See Table 1 in box "Any other information on results incl. tables".

Other effects:

At 7 days after treatment, slight scaliness was observed in the two rabbits that showed skin irritation during the first days on the edges of the application area (<1 mm) only. At 14 days after treatment, the scaliness had cleared.

Table 1 - Skin irritation scores of ethyl lactate, after a single 4-hour dermal exposure

Animal no.	Hours or days after removal of the test material:
	1 hr	24 hr	48 hr	72 hr	7 d
	A-B	A-B	A-B	A-B	A-B
12	0-0 (1-1)	0-0 (2-2)	0-0 (2-2)	0-0 (2-1)	0-0
8	0-0 (1-1)	0-0 (2-2)	0-0 (2-2)	0-0 (2-1)	0-0
14	0-0 (1-1)	0-0 (1-1)	0-0	0-0
Erythema (A):	0.0	0.0	0.0	0.0	0.0
Oedema (B):	0.0	0.0	0.0	0.0	0.0

 

() Skin effects were located on a very small skin area on the edge of the application area (width less than 1 mm), most probably caused by pressure of the bandage on the test patch underneath. Therefore, the toxicological significance of these skin effects is considered dubious.

Interpretation of results:

other: CLP criteria not met

Conclusions:

Under the given conditions, the test item is not irritating to the skin of rabbits.

Executive summary:

In a primary dermal irritation study (according to OECD Guideline 404), young adult male SPF bred New Zealand White albino rabbits (n= 3; weight 2130 - 2220 g) were dermally exposed to 0.5 mL of ethyl (S)-lactate (purity: 98%) to an area of 2.5 x 2.5 cm under occlusive conditions for 4 hours. Animals were then observed for 14 days and irritation was scored by the method of Draize et al. Only mild skin effects were observed on a very small skin area on the edge of the application area, most probably by pressure of the bandage on the test patch underneath. Since normally these kind of exposure conditions will not occur in humans, the toxicological significance of these skin effects was considered dubious. Furthermore, the mean erythema and oedema scores were 0. Based on these results, Ethyl (S)-lactate can be considered as non-irritant to the skin of rabbits. Therefore, classification for skin irritation according to CLP Regulation 1272/2008 is not warranted.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Remarks:

Chicken Enucleated Eye Test (validated alternative test)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1995-06-19 to 1995-07-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 438 (Isolated Chicken Eye Test Method for Identifying Ocular Corrosives and Severe Irritants)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material used in the report: ethyl lactate
- CAS number: 687-47-8
- Batch number: 950614
- Appearance: liquid
- Purity: 98 %
- Storage: ambient

Species:

chicken

Strain:

other: ROSS, spring chickens

Details on test animals or tissues and environmental conditions:

Approximately 7 weeks old, male or female chickens (Ross, spring chickens), body weight range approximately 2.5 - 3.0 kg, were used as eye-donors.

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

0.03 mL

Duration of treatment / exposure:

10 seconds

Observation period (in vivo):

4 hours

Number of animals or in vitro replicates:

4 eyes

Details on study design:

Approximately 7 weeks old, male or female chickens (Ross, spring chickens), body weight range approximately 2.5 - 3.0 kg, were used as eye-donors. Heads of these animals were obtained from poultry slaughterhouse v.d. Bor, Amerfoortseweg 118, Nijkerkerveen, the Netherlands. Heads of the animals were cut off immediately after sedation of the animals by electric shock and incision of the neck for bleeding, and before they reached the next station on the process line. The heads were placed in small plastic boxes (3 heads per box) on a bedding of paper tissues moistened with isotonic saline. Next, they were transported to the testing facility. During transportation, the heads were kept at ambient temperature. Within 2 hours after kill, eyes were carefully dissected and placed in a superfusion apparatus using the following procedure: First the eye-lids were carefully removed without damaging the cornea and a small drop of Fluorescein sodium BP 2% w/v (Minims, Smith & Nephew Ltd., Romford, England) was applied to the corneal surface for a few seconds and subsequently rinsed off with isotonic saline of ambient temperature. Next, the head with the fluorescein-treated cornea was examined with a slit-lamp microscope (Slit-lamp 900 CN, Haag-Streit AG, Liebefeld-Bern, Switzerland), to ensure that the cornea was not damaged. If undamaged, the eye was further dissected from the head without damaging the eye or cornea. Care was taken to remove the eye-ball from the orbit without cutting off the optical nerve too short. The enucleated eye was placed in a stainless steel clamp with the cornea positioned vertically and transferred to a chamber of the superfusion apparatus (TNO, Zeist, the Netherlands). The clamp holding the eye was positioned in such a way that the entire cornea was supplied with isotonic saline from a bent, stainless steel tube, at a rate of ca 0.10 - 0.15 ml/min (peristaltic pump, Desaga STA 131900, Heidelberg, Germany). The chambers of the superfusion apparatus as well as the saline were temperature controlled at 32 ± 1.5 °C (water pump, Thermomix 1441 , B. Braun Melsungen AG, Melsungen, Germany). After placing in the superfusion apparatus, the eyes were examined again with the slit-lamp microscope to ensure that they were not damaged. Corneal thickness was measured using the Depth Measuring Attachment no. II for the Haag-Streit slit-lamp microscope. Thickness of the cornea was expressed in instrument units. An accurate measurement was taken at the corneal apex of each eye. Eyes with a corneal thickness deviating more than 10% of the average corneal thickness of the eyes, or eyes that were unacceptably stained with fluorescein (score higher than 0.5), indicating the cornea to be permeable, or eyes that showed any other signs of damage, were rejected as test eyes and replaced, if necessary. Four eyes were selected for testing. After an equilibration period of 45-60 minutes, the corneal thickness of the eyes were measured again to determine the zero reference value for corneal swelling calculations. The sample of the test substance was tested undiluted on three test eyes and one additional eye was rinsed with isotonic saline only and served as a control of the experimental conditions. At time t = 0, i.e . immediately after the zero reference measurement, the test substance was applied to the eye. For this purpose, the clamp holding the eye was placed on paper tissues outside the chamber with the cornea facing upwards. The test substances was applied in amounts of 0.03 ml from a micropipette (Nichiryo Co., Ltd., model 8100, Tokyo, Japan), in such a way that the entire surface of the cornea was bathed with the test material. With the solid sample, the cornea was powdered with 0.03 g of the test material. After a total exposure period of 10 seconds, the corneal surface was rinsed thoroughly with 20 ml of isotonic saline of ambient temperature. After rinsing, each eye in the holder was returned to its chamber. This procedure was repeated for each test eye.
The control eye and test eyes were examined at 0, 30, 75, 120, 180 and 240 minutes after treatment, using the criteria and scoring system, given in the appendix. Fluorescein retention was only scored at 30 minutes after treatment. All examinations were carried out with the slit-lamp microscope.

Irritation parameter:

corneal swelling 

Run / experiment:

at 30 min

Value:

10

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

cornea opacity score

Run / experiment:

at 30 min

Value:

1

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

fluorescein retention score

Run / experiment:

at 30 min

Value:

3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Remarks on result:

other:

Remarks:

fluorescein retention was only determined at t = 30 min

Irritation parameter:

corneal swelling 

Run / experiment:

at 75 min

Value:

15

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

cornea opacity score

Run / experiment:

at 75 min

Value:

2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

corneal swelling 

Run / experiment:

at 120 min

Value:

24

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

cornea opacity score

Run / experiment:

at 120 min

Value:

2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

corneal swelling 

Run / experiment:

at 180 min

Value:

27

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

cornea opacity score

Run / experiment:

at 180 min

Value:

2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

corneal swelling 

Run / experiment:

at 240 min

Value:

31

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Irritation parameter:

cornea opacity score

Run / experiment:

at 240 min

Value:

2.3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

not applicable

Other effects / acceptance of results:

After treatment, the thickness of the cornea of the test eyes gradually increased considerably; a maximum mean corneal swelling of 31% was obtained at 240 min after treatment. Moderate or severe corneal opacity and severe fluorescein retention by damaged epithelial cells were observed in the test eyes. In addition, the three test eyes showed wrinkling of the corneal epithelium. The irritancy categories assigned to these findings for corneal swelling, corneal opacity, and fluorescein retention were: III, III and IV.

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Conclusions:

Under the given conditions, the test item is considered severely irritating to eyes.

Executive summary:

In an ex vivo bioassay, the Chicken Enucleated Eye Test (CEET), 0.03 mL of undiluted ethyl-(S)-lactate (purity: 98 %) was applied to enucleated chicken eyes for 10 seconds, after which the corneal surface was rinsed with 20 mL of isotonic saline. The eyes were then examined up to 4 hours after treatment. Irritation was scored as thickness of the cornea, corneal opacity and fluorescein retention.

After treatment, the thickness of the cornea of the test eyes gradually increased considerably; a maximum mean corneal swelling of 31 % was obtained at 240 min after treatment. Moderate or severe corneal opacity and severe fluorescein retention by damaged epithelial cells were observed in the test eyes. In addition, the three test eyes showed wrinkling of the corneal epithelium. Based on this results the test item was considered severely irritating to the eyes. Therefore, classification of ethyl-(S)-lactate as Eye Dam. 1 (H318) according to the CLP Regulation 1272/2008 is warranted.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

In an acute dermal irritation study, three young adult male SPF bred New Zealand White albino rabbits (weight 2130-2220 g) were dermally exposed to 0.5 mL of undiluted ethyl lactate to an area of 2.5 × 2.5 cm. Test sites were covered with an occlusive dressing for 4 hours. Animals were observed for 14 days. Irritation was scored by the method of Draize et al. Only mild skin effects were observed on a very small skin area on the edge of the application area, most probably by pressure of the bandage on the test patch underneath. Since normally this kind of exposure conditions will not occur in humans, the toxicological significance of these skin effects is considered to be dubious. In this study, ethyl lactate was not a dermal irritant.

In an ex vivo bioassay, the Chicken Enucleated Eye Test (CEET), 0.03 mL of undiluted ethyl lactate was applied to enucleated chicken eyes for 10 seconds, after which the corneal surface was rinsed with 20 mL of isotonic saline. The eyes were then examined up to 4 hours after treatment. Irritation was scored as thickness of the cornea, corneal opacity, and fluorescein retention.

After treatment, the thickness of the cornea of the test eyes gradually increased considerably; a maximum mean corneal swelling of 31 % was obtained at 240 min after treatment. Moderate or severe corneal opacity and severe fluorescein retention by damaged epithelial cells were observed in the test eyes. In addition, the three test eyes showed wrinkling of the corneal epithelium.

In a sensory irritation study (see section 7.2.2), the RD50 values of ethyl (S)-lactate were 772 mg/m³ in mice and 791 mg/m³ in rats.

Based on the results and according to Annex VI of CLP Regulation 1272/2008, classification as Eye Dam. 1, H318 and STOT SE 3, H335 is warranted for the target substance ethyl (S)-lactate.

Justification for classification or non-classification

Based on the available data and according to Annex VI of CLP Regulation 1272/2008, classification as Eye Dam. 1, H318 and STOT SE 3, H335 is warranted for the target substance ethyl (S)-lactate.