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Toxicological information

Eye irritation

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Administrative data

Endpoint:
eye irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1996-11-25 to 1996-12-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 405 (Acute Eye Irritation / Corrosion)
Version / remarks:
1987-02-24
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Hexanoic acid, 2-ethyl-, zinc salt, basic
EC Number:
286-272-3
EC Name:
Hexanoic acid, 2-ethyl-, zinc salt, basic
Cas Number:
85203-81-2
Test material form:
liquid: viscous

Test animals / tissue source

Species:
rabbit
Strain:
New Zealand White
Details on test animals or tissues and environmental conditions:
TEST ANIMALS
- Source: Broekman Institute, Someren, The Netherlands
- Age at study initiation: approx. 7 weeks
- Weight at study initiation: 1289 - 1599 g
- Housing: individually in labelled cages with perforated floors (Scanbur Denmark) and equipped with an automatic drinking system (ITL, Bergen, The Netherlands).
- Diet: standard laboratory rabbit diet (LKK-20, pellet diameter 4 mm, Hope Farms, Woerden, The Netherlands) approx. 100 g per day. Hay (BMI, Helmond, The Netherlands) was provided once a week.
- Water (ad libitum): tap-water diluted with decalcified water
- Acclimation period: at least 5 days before start of treatment

A health inspection was performed prior to commencement of treatment, to ensure that the animals were in a good state of health. Special attention was paid to the eyes, which were free from any abnormality.

ENVIRONMENTAL CONDITIONS
- Temperature: 21°C
- Relative humidity: 50%
- Air changes: approximately 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12/12

Test system

Vehicle:
unchanged (no vehicle)
Controls:
no
Amount / concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 mL of the test substance was instilled in the conjunctival sac of one eye of each animal after gently pulling the lower lid away from the eyeball. The lids were then gently held together for about one second to prevent loss of the test substance. The other eye remained untreated and served as the reference control.
Duration of treatment / exposure:
not applicable
Observation period (in vivo):
approximately 1, 24, 48 and 72 hours and 7, 14 and 21 days* after instillation of the test substance
(*except for one of the animals, whose eyes were also examined daily from 21 days up to 29 days)
Number of animals or in vitro replicates:
3 male rabbits
Details on study design:
A health inspection was performed prior to commencement of treatment, to ensure that the animals were in good state of health. Special attention was paid to the eyes, which were free from any abnormality.

SCORING SYSTEM: according to the Draize scoring system
The irritation scores and a description of all other (local) effects were recorded.

TOOL USED TO ASSESS SCORE:
Immediately after the 24 hour observation, a solution of 2% fluorescein in water (adjusted to pH 7.0) was instilled into both eyes of each animal to quantitatively determine corneal epithelial damage. When considered necessary, this procedure was repeated to assess recovery. Any bright green stained area, indicating epithelial damage, was estimated as a percentage of the total corneal area.
In case standard lightning was considered inadequate for observing minor effects, eye examinations were performed using an ophthalmic examination lamp.
In cases of equivocal results when comparing the treated and untreated eyes, the illustrated guide from Consumer Product Safety Commission, Washington, D.C. 20207 was used for additional control purposes.

OBSERVATIONS:
- Mortality/Viability: twice daily
- Toxicity: at least once daily
- Body weight: day of treatment (prior to instillation).

Results and discussion

In vivo

Resultsopen allclose all
Irritation parameter:
cornea opacity score
Basis:
mean
Remarks:
animal #1
Time point:
24/48/72 h
Score:
0.67
Max. score:
4
Reversibility:
fully reversible within: 7 days
Remarks on result:
other: 24 h: epithelial damage (25% of the corneal area), white covering on the eyelids; 48 h: white covering on the eyelids; 72 h: epithelial damage (25%), reduced elasticity of eyelids; 7 d: epithelial damage (10%), pannus, neovascularisation of the cornea
Irritation parameter:
iris score
Basis:
mean
Remarks:
animal #1
Time point:
24/48/72 h
Score:
0.33
Max. score:
2
Reversibility:
fully reversible within: 7 days
Irritation parameter:
conjunctivae score
Basis:
mean
Remarks:
animal #1
Time point:
24/48/72 h
Score:
3
Max. score:
3
Reversibility:
fully reversible within: 14 days
Remarks on result:
other: 24 h: redness of nictitating membrane; 48 h & 72 h: redness of eyelids and sclera; 7 d: redness of sclera
Irritation parameter:
chemosis score
Basis:
mean
Remarks:
animal #1
Time point:
24/48/72 h
Score:
2
Max. score:
4
Reversibility:
fully reversible within: 14 days
Remarks on result:
other: 24 h: chemosis of the eyelids; 48 h & 72 h: chemosis of eyelids, nictitating membrane & sclera; 7 d: chemosis of sclera
Irritation parameter:
cornea opacity score
Basis:
mean
Remarks:
animal #2
Time point:
24/48/72 h
Score:
0
Max. score:
4
Remarks on result:
other: 24 h: white covering on the eyelids
Irritation parameter:
iris score
Basis:
mean
Remarks:
animal #2
Time point:
24/48/72 h
Score:
0
Max. score:
2
Irritation parameter:
conjunctivae score
Basis:
mean
Remarks:
animal #2
Time point:
24/48/72 h
Score:
2.33
Max. score:
3
Reversibility:
fully reversible within: 14 days
Remarks on result:
other: 24 h: redness of eyelids, nictitating membrane & sclera; 48 h & 72 h: redness of eyelids; 7 d: redness of eyelids
Irritation parameter:
chemosis score
Basis:
mean
Remarks:
animal #2
Time point:
24/48/72 h
Score:
1
Max. score:
4
Reversibility:
fully reversible within: 72 hours
Remarks on result:
other: 24 h: chemosis of eyelids; 48 h: chemosis of eyelids, nictitating membrane & sclera
Irritation parameter:
cornea opacity score
Basis:
mean
Remarks:
animal #3
Time point:
24/48/72 h
Score:
0.67
Max. score:
4
Reversibility:
fully reversible within: 14 days
Remarks on result:
other: 24/48 h: epithelial damage (25% of corneal area) and/or white covering on eyelids; 72 h / 7 d: epithelial damage (25%)and/or eye lids stuck together (released by soaking with water); 14 d: epithelial damage (10%), pannus, neovascularisation of the cornea
Irritation parameter:
iris score
Basis:
mean
Remarks:
animal #3
Time point:
24/48/72 h
Score:
0
Max. score:
2
Remarks on result:
other: 7 d: moderate effect on the iris (grade 1)
Irritation parameter:
conjunctivae score
Basis:
mean
Remarks:
animal #3
Time point:
24/48/72 h
Score:
3
Max. score:
3
Reversibility:
fully reversible within: 21 days
Remarks on result:
other: 24 h: redness of the eyelids; 48 h: redness of the eyelids & sclera; 72 h: redness of the sclera; 7 d: redness of the eyelids & sclera; 14 d: redness of the sclera
Irritation parameter:
chemosis score
Basis:
mean
Remarks:
animal #3
Time point:
24/48/72 h
Score:
1.33
Max. score:
4
Reversibility:
fully reversible within: 14 days
Remarks on result:
other: 24 h/48 h/72 h / 7 d: chemosis of the eyelids, nictitating membrane & sclera
Irritant / corrosive response data:
Instillation of 0.1 mL of hexanoic acid, 2-ethyl-, zinc salt, basic into one eye of each of three rabbits resulted in effects on the cornea, iris and conjunctivae, among the animals.
Two animals showed corneal injury consisting of opacity (maximum grade 1-2) and epithelial damage (maximum 25% of the corneal area). As a result of the corneal injury, pannus, neovascularisation of the cornea, was apparent 7 days after instillation in one animal and 14 days after instillation in the second animal.
The corneal injury had resolved within 14 days in the first animal and within 21 days in the second animal. No corneal injury was observed in the third animal.
Iridic irritation grade 1 was observed in one animal after 1 hour, in the second animal after 1 and 24 hours and in the third animal after 1 hour and 7 days. The irritation of the conjunctivae consisted of redness, chemosis and discharge and had completely resolved within 14 days in two animals and within 21 days in the third animal.

A white covering was observed on the eyelids of all animals 24 and/or 48 hours after instillation. Reduced elasticity of the eyelids was noted in one animal 72 hours after instillation. The eyelids of another animal were stuck together, 7 days after instillation and were released by soaking with abundant water.

Unexpectedly, one animal, which was free of any ocular irritation after 14 days, showed signs of ocular irritation between 21 and 29 days after instillation. The irritation consisted of corneal injury (opacity, epithelial damage and pannus), iridic irritation and conjunctival irritation. Minimal discharge persisted after 29 days (termination of the study). This irritation, which showed a relative slow recovery, was considered not to be related to the test substance treatment but to have been caused by accident. The latter results were excluded from interpretation.

There was no evidence of ocular corrosion.

No staining of peri-ocular tissues by the test substance was observed.
Other effects:
- Toxicity/Mortality: no symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred.

Applicant's summary and conclusion

Interpretation of results:
Category 2 (irritating to eyes) based on GHS criteria
Conclusions:
The test item is considered to be irritating to the eyes. The test item does not cause serious (i.e. irreversible) damage to the eyes.
According to the EC Regulation No. 1272/2008 and subsequent regulations, the substance is classified as irritating to eyes (Category 2).