Ammonium 2-mercaptopropionate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From October 28, 1999 and November 16, 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Commission Directive 92/69/EEC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Ammonium 2-mercaptopropionate

EC Number:

236-526-4

EC Name:

Ammonium 2-mercaptopropionate

Cas Number:

13419-67-5

Molecular formula:

C3H9NO2S

IUPAC Name:

ammonium 2-sulfanylpropanoate

Test material form:

liquid

Details on test material:

colourless

Test animals / tissue source

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

Three New Zealand White rabbits, supplied by David Percival Ltd, Moston, UK, were used. At the start of the study the animals weighed 2.64 to 2.80 kg and were twelve to sixteen weeks old. After a minimum acclimatisation period of five days each animal was given a number unique within the study which was written with a black indelible marker-pen on the inner surface of the ear and on the cage label.

The animals were individually housed in suspended metal cages. Free access to mains drinkinng water and food (ST AN RAB SQC Rabbit Diet, Special Diets Services Ltd, UK) was allowed throughout the study.

The temperature and relative humidity were controlled to remain target ranges of 17 to 23 °C and 30 to 70 % respectively. Occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was approximately fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light and twelve hours darkness.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent negative control

Amount / concentration applied:

0.1 mL

Duration of treatment / exposure:

15 days

Observation period (in vivo):

15 days

Number of animals or in vitro replicates:

3

Details on study design:

Immediately before the start of the test, both eyes of the provisionally selected test rabbits were examined for evidence of ocular irritation or defect with the aid of a light source from a standard ophthalmoscope. Animals showing evidence of ocular lesions were rejected and replaced.

One rabbit was initially treated. A volume of 0.1 mL of the test substance was instilled into the conjunctival sac of the right eye, formed by gently pulling the lower lid away from the eye ball. The upper and lower eye lids were held together for about one second immediately after installation, to prevent loss of the test substance, and then released. The left eye remained untreated and was used for control purposes. Immediately after administration of the test substance, an assessment of the initial pain reaction was made.

After consideration of the ocular responses produced in the first treated animal, two additional animals were treated. In order to minimise pain on instillation of the test substance, one drop of local anaesthetic (Amethocaine hydrochloride, Chauvin Pharmaceutials, UK) was instilled into both eyes of these animals 1 to 2 minutes before treatment.

Assessment of ocular damage/irritation was made approximately 1 hour and 24, 48 and 72 hours following treatment, according to the numerical evaluation 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.48 to 49).

Any other ocular effects were also noted. Examination of the eye was facilitated by the use the light source from a standard ophthalmoscope.
Additional observations were made on Days 7 and 14 or 15 to assess the reversibility of the ocular effects.

Due to a technical error, the Day 14 observation on the initial animal was performed one day late, on Day 15. This deviation from the Standard Test Method was considered not to effect the purpose or integrity of the study.

Classification according to a modified version of the Kay and Calandra system:
The numerical values corresponding to each animal, tissue and observation time were recorded. The data relating to the conjunctivae were designated by the letters A (redness), B (chemosis) and C (discharge), those relating to the iris designated by the letter D and those relating to the cornea by the letters E (degree of opacity) and F (area of opacity). For each tissue the sore was calculated as follows:
Score for conjunctivae: (A + B + C) x 2
Score for iris: D x 5
Score for cornea: (E x F) x 5
Using the numerical data obtained a modified version of the system described by Kay J H and Calandra J C, J. Soc. Cosmet. Chem., 1962 13 281-289 was used to classify the ocular irritancy potential of the test substance. This was achieved by adding together the scores for the cornea, iris and conjunctivae for each time point for each rabbit.
The group means of the total scores for each observation were calculated. The highest of these group means (the maximum group mean score) together with the persistence of the reactions enabled classification of the eye irritancy potential of the test substance. If any rabbit shows irreversible ocular damage the test substance will be classified as corrosive to eye.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

maximum mean total score (MMTS)

Basis:

mean

Remarks:

of 3

Time point:

other: 15 d

Score:

39.3

Reversibility:

fully reversible within: 15 d

Remarks on result:

positive indication of irritation

Results 2

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.7

Max. score:

4

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 3

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 4

Irritation parameter:

cornea opacity score

Basis:

animal #3

Time point:

24/48/72 h

Score:

1.7

Max. score:

4

Reversibility:

fully reversible within: 15 d

Remarks on result:

positive indication of irritation

Results 5

Irritation parameter:

iris score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.7

Max. score:

2

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 6

Irritation parameter:

iris score

Basis:

animal #2

Time point:

24/48/72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 7

Irritation parameter:

iris score

Basis:

animal #3

Time point:

24/48/72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 15 d

Remarks on result:

positive indication of irritation

Results 8

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

24/48/72 h

Score:

2

Max. score:

3

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 9

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

24/48/72 h

Score:

2.3

Max. score:

3

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 10

Irritation parameter:

conjunctivae score

Basis:

animal #3

Time point:

24/48/72 h

Score:

2.3

Max. score:

3

Reversibility:

fully reversible within: 15 d

Remarks on result:

positive indication of irritation

Results 11

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 12

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

24/48/72 h

Score:

2.3

Max. score:

4

Reversibility:

fully reversible within: 14 d

Remarks on result:

positive indication of irritation

Results 13

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

24/48/72 h

Score:

2.7

Max. score:

4

Reversibility:

fully reversible within: 15 d

Remarks on result:

positive indication of irritation

Irritant / corrosive response data:

- Dulling of the normal lustre of the cornea was noted in two treated eyes 1-hour after treatment. Diffuse corneal opacity was noted in all treated eyes at the 24-hour observation. Translucent corneal opacity was noted in one treated eye with diffuse corneal opacity in two treated eyes at the 48-hour observation. Translucent corneal opacity was noted in one treated eye with diffuse corneal opacity in one other treated eye at the 72-hour observation. Diffuse corneal opacity was noted in two treated eyes at the 7-day observation.
- lridial inflammation was noted in one treated eye 1-hour after treatment, in all treated eyes at the 48-hour observations, in two treated eyes at the 72-hour observations and persisted in one treated eye at the 7-day observation.
- Moderate conjunctiva irritation was noted all treated eyes 1-hour after treatment and at the 24-hour observation. Severe conjuntival irritation was noted in two treated eyes with moderate conjunctiva irritation in the remaining treated eye at the 48-hour observation. Severe conjunctival irritation persisted in one treated eye with moderate conjunctiva irritation in two treated eyes at the 72-hour observation. Minimal conjunctival irritation was noted in all treated eyes at the 7-day observation.
- Vascularisation, with a generalised ingrowth of vessels for approximately 2 - 3 mm, was noted in one treated eye at the 7-day observation.
- Two treated eyes appeared normal at the 14-day observation and the remaining treated eye appeared normal at the 15-day observation.

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

Under the study conditions, the test substance produced a maximum group mean score of 39.3.

Executive summary:

A study was conducted to determine the irritancy potential of the test substance to the eye of the New Zealand White rabbit according to OECD Guideline 405 and of Commission Directive 92/69/EEC, in compliance with GLP. A single instillation of the test substance to the non-irrigated eye of 3 rabbits produced diffuse to translucent corneal opacity, iridial inflammation and moderate to severe conjunctiva irritation. Dulling of the normal lustre of the cornea and vascularisation, with a generalised ingrowth of vessels for approximately 2 – 3 mm, was also noted. Two treated eyes appeared normal at the 14 d observation and the remaining treated eye appeared normal at the 15 d observation. Under the study conditions, the test substance produced a maximum group mean score of 39.3 (Sanders, 2000).