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Administrative data

Description of key information

Ethyl-S-lactate is highly irritating to the eye and to the respiratory tract.

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:
June 26, 1995 - July 10, 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study
Qualifier:
according to
Guideline:
OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
Qualifier:
according to
Guideline:
EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)
GLP compliance:
yes
Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: SPF bred New Zealand White albino rabbits were obatined 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°C
- Humidity (%): 52.5-75%
- Air changes (per hr): ca 10 air changes/hours
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours dark cycle
Type of coverage:
semiocclusive
Preparation of test site:
other: clipping
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 apllication site by means of adhesive tape. Subsequently, the entire trunk of the rabbit was wrapped with self-adhesive-gauze to maintain the patch in postion and to retard evaporation of volatile substances. The gauze was additionaly 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 wer evaluated by the method of Draize et al. (J. Pharmacol. Exp. Ther. 82 (1994) 377-390). Further skin readings were made at approximately 24, 48 and 72 hours, and at 7 and 14 days after treatment.
Irritation parameter:
overall irritation score
Basis:
mean
Time point:
other: 1
Score:
0
Max. score:
0
Irritant / corrosive response data:
Table 1 - Skin irritation scores of ethyllactate , 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.
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 ethyllactate, 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:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Ethyl lactate is not irritating or corrosive to (human) skin
Executive summary:

In a acute dermal irritation study, 3 young adult male SPF bred New Zealand White albino rabbits (weight 2130 -2220 g) were dermally exposed to 0.5 ml of undiluted ethyllactate to an area of 2.5 x 2.5 cm. Test sites were covered with an occlusive dressing for 4 hours. Animals were the 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 these kind of exposure conditions will not occur in humans, the toxicological significance of these skin effects is considered dubious. In this study, ethyl lactate is not a dermal irritant.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records
Reference
Endpoint:
eye irritation
Remarks:
other: Chicken Enucleated Eye Test (validated alternative test)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23 June 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study
Qualifier:
no guideline available
Principles of method if other than guideline:
- Burton, A.B.G. (1971) A method for the objective assessment of eye irritation. Food and Cosmetics Toxicology 10, 209-217.
- Burton, A.B.G., M. York and R.S. Lawrence (1981) The in vitro assessment of severe irritants. Food and Cosmetics Toxicology 19, 471-480.
- Commission of the European Communities (1991) Collaborative study on the evaluation of alternative methods to the eye irritaüon test. EC Document XI/632/91, V/E/1/131/91.
- Koëter, H.B.W.M. and M.K. Prinsen (1985) Introduction of an in vitro eye irritation test as a possible contribution to the reduction of the number of animals in toxicity testing. TNO Report V85.188/140322, May 1985, Dept. of Biological Toxicology, TNO Toxicology and Nutrition Institute, Zeist, The Netherlands (available upon request).
- Koëter, H.B.W.M. and M.K. Prinsen (1985) Comparison of in vivo and in vitro eye irritancy test systems: A study with 34 substances. Alternative methods in Toxicology, Volume 3, Chapter A9. Mary Ann Liebert, Inc., publishers.
- Price, J.B.and IJ. Andrews (1985) The in vitro assessment of eye irritancy using isolated eyes.
Food and Chemical Toxicology 23 (2)., 313-315. - Prinsen, M.K.and H.B.W.M. Koëter (1985) EC-Validation study on alternatives to the Draize eye irritation test. Pilot Interlaboratory comparison of the enucleated eye test. TNO Report V89.464, April 1990, Dept. of Biological Toxicology, TNO Toxicology and Nutrition Institute, Zeist, The Netherlands (available upon request).
- Prinsen, M.K. and H.B.W.M. Koëter (1994) Justification of the Enucleated Eye Test with eyes of slaughterhouse animals as an alternative to the Draize eye irritation test with rabbits. Food and Chemical Toxicology, Volume 31, l, 69-76.
- Prinsen, M .K . The Chicken Enucleated Eye Test (CEET): a practical (pre)screen for the assessment of eye irritation/corrosion potential of test materials. Food and Chemical Toxicology, scheduled to be published in Volume 34, no. 4, April 1996.
GLP compliance:
yes
Species:
other: 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:
other: control eye
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 wer 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 incission of the neck for bleeding, and before thery 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 (waterpump, 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 fluores- cein (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:
other: corneal swelling
Basis:
other: Enucleated eye
Time point:
other: 240
Score:
3
Reversibility:
other: not relevant
Irritation parameter:
other: corneal opacity
Basis:
other: Enucleated eye
Time point:
other: 240
Score:
3
Reversibility:
other: not relevant
Irritation parameter:
other: fluorescein retention
Basis:
other: Enucleated eye
Time point:
other: 240
Score:
4
Reversibility:
other: not relevant
Irritant / corrosive response data:
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:
moderately irritating
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Classification: ethyl lactate can be considered severely irritating to eyes (R41).
Executive summary:

In an ex vivo bio assay, 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 fluorecein 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 epithelila cells were observed in the test eyes. In addition, the three test eyes showed wrinkling of the corneal epithelium. On the basis of the results obtained with this in vitro (ex vivo) assay and according to the scheme for (EC-)classification applied, the following was concluded: ethyl lactate is moderately irritating to eyes, but in view of the additional effects observed, it is recommended to classify ethyl lactate as R41: risk of serious damage to eyes.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

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 bio assay, 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. On the basis of the results obtained with this in vitro (ex vivo) assay and according to the scheme for (EC-)classification applied, the following was concluded: Ethyl lactate is moderately irritating to eyes, but in view of the additional effects observed, it is recommended to classify ethyl lactate as R41: risk of serious damage to eyes.

In a sensory irritation study (see section 7.2.2), the RD50 values of ethyl-(L)-lactate were 772 mg/m³ in mice and 791 mg/m³ in rats. In the same study an RD50 of 760 mg/m³ in mice and 701 mg/m³ in rats was found for n-butyl-L-lactate. The similarity in the results for ethyl-L-lactate and n-butyl-L-lactate support the conclusion that the effects on breathing rate can be attributed to irritating effects from the lactic acid formed during hydrolysis of the substances (see statement in section 7.9.3), which is a rapid process during and after uptake in the organism. The sensory irritating effect is thus a pH effect and not a toxic effect.


Effects on eye irritation: highly irritating

Effects on respiratory irritation: irritating

Justification for classification or non-classification

Ethyl-S-lactate shall be classified as damaging to the eye (Eye Dam. 1, H319) and irritating to the respiratory tract (STOT SE 3) under EU Regulation 1272/2008.