Ethyl 2,6,6-trimethylcyclohexa-1,3-ene-1-carboxylate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

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

Adequacy of study:

key study

Study period:

2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Guideline study performed under GLP. The source and target substances are isomeric. The structures differ only in the relative position of an alkyl group. The target and source share common structural elements in the same relative positions. The source and target have very similar physicochemical properties and thus have similar expected toxicokinetic behaviour. The substances have similar in silico chemical reactivity and toxicity predictions. This is observed within available in vivo toxicology testing where low level local and systemic toxicity is demonstrated and comparable between target and source. The substances therefore demonstrate chemical similarity.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

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:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected August 2005; signature: November 2005

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl 2,6,6-trimethylcyclohexa-2,4-diene-1-carboxylate

EC Number:

252-333-8

EC Name:

Ethyl 2,6,6-trimethylcyclohexa-2,4-diene-1-carboxylate

Cas Number:

35044-57-6

Molecular formula:

C12H18O2

IUPAC Name:

ethyl 2,6,6-trimethylcyclohexa-2,4-diene-1-carboxylate

Test material form:

gas under pressure: refrigerated liquefied gas

Details on test material:

- Physical state: liquid
- Storage condition of test material: approximately 4°C in the dark
- Other: Clear colourless.

Test animals / tissue source

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Recognised animal supplier
- Age at study initiation: 12-20 weeks old
- Weight at study initiation: 2.0 - 3.5 kg
- Housing: individually housed in suspended metal cages
- Diet: certified rabbit food ad libitum
- Water: mains water ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17 - 23
- Humidity (%): 30 - 70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 hour light/12 hour dark

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

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

Duration of treatment / exposure:

A volume of 0.1 ml of the test material, was placed into the conjunctival sac of the right eye, formed by gently pulling the lower lid away from the eyeball. The upper and lower eyelids were held together for about one second immediately after treatment, to prevent loss of the test material, and then released. The left eye remained untreated and was used for control purposes.

Observation period (in vivo):

The eyes of each animal were examined approximately 1, 24, 48 and 72 hours after instillation of the test substance.

Number of animals or in vitro replicates:

3 males

Details on study design:

The study was performed in a stepwise manner and was started by treatment of a single rabbit. The two other animals were treated in a similar manner after considering the degree of eye irritation observed in the first animal.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): none

SCORING SYSTEM:
The irritation was assessed according to the following numerical scoring system. At each observation, the highest scores given were recorded:

CORNEAL IRRITATION
Opacity: degree of density (area most dense taken for reading)
No ulceration or opacity (may include slight dulling of normal luster) 0
Scattered or diffuse areas of opacity, details of iris clearly visible 1
Easily discernible translucent area, details of iris slightly obscured 2
Nacreous area, no details of iris visible, size of pupil barely discernible 3
Opaque cornea, iris not discernible through the opacity 4

Area of cornea involved:
No ulceration or opacity 0
One quarter or less but not zero 1
Greater than one quarter, but less than half 2
Greater than half, but less than three quarters 3
Greater than three quarters, up to whole area 4

IRIS
Normal 0
Markedly deepened rugae, congestion, swelling, moderate circumcorneal hyperaemia,
or injection, any of these or combination thereof, iris still reacting to light
(sluggish reaction is positive) 1
No reaction to light, hemorrhage, gross destruction (any or all of these) 2

CONJUNCTIVAL IRRITATION
Redness (refers to palpebrae and sclera, excluding cornea and iris):
Blood vessels normal 0
Some blood vessels definitely hyperaemic (injected) 1
Diffuse, crimson color, individual vessels not easily discernible 2
Diffuse beefy red 3

Chemosis (refers to lids and/or nictitating membranes):
No swelling 0
Any swelling above normal (includes nictitating membranes) 1
Obvious swelling with partial eversion of lids 2
Swelling with lids about half closed 3
Swelling with lids more than half closed 4

Discharge:
No discharge (may include small amounts observed in inner canthus of normal animals) 0
Any amount different from normal and/or lacrimation 1
Discharge with moistening of the lids and hairs just adjacent to lids 2
Discharge with moistening of the lids and hairs (considerable area around the eye) 3

TOOL USED TO ASSESS SCORE: Examination of the eye was facilitated by the use of the light source from a standard ophthalmoscope.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: 24, 48 and 72h

Score:

0

Max. score:

4

Results 2

Irritation parameter:

iris score

Basis:

mean

Time point:

other: 24, 48 and 72h

Score:

0

Max. score:

2

Results 3

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

other: 24, 48 and 72h

Score:

0.33

Max. score:

3

Reversibility:

fully reversible

Results 4

Irritation parameter:

chemosis score

Basis:

mean

Time point:

other: 24, 48 and 72h

Score:

0

Max. score:

4

Irritant / corrosive response data:

No corneal effects were noted. Iridial inflammation was noted in one treated eye one hour after treatment. Minimal to moderate conjunctival irritation was noted in all treated eyes one hour after treatment with minimal conjunctival irritation noted in all treated eyes at the 24-hour observation. All treated eyes appeared normal at the 48-hour observation.

Any other information on results incl. tables

Table 1. Individual scores and mean scores for 24, 48 and 72 hours

Organism number and sex	Time after treatment	Corneal Opacity	Iridial Inflammation	Conjunctival Redness	Conjunctival Chemosis
1 (male)	1h	0	1	2	1
	24 h	0	0	1	0
	48 h	0	0	0	0
	72 h	0	0	0	0
Mean (24 – 72 h)		0.00	0.00	0.33	0.00
2 (male)	1h	0	0	1	1
	24 h	0	0	1	0
	48 h	0	0	0	0
	72 h	0	0	0	0
Mean (24 – 72 h)		0.00	0.00	0.33	0.00
3 (male)	1h	0	0	1	1
	24 h	0	0	1	0
	48 h	0	0	0	0
	72 h	0	0	0	0
Mean (24 – 72 h)		0.00	0.00	0.33	0.00

 

Applicant's summary and conclusion

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the conditions of this study the test material is not irritating to the eye.

Executive summary:

The study was performed to EU Method B.5 an OECD TG 405 under GLP to assess the irritancy potential of the test material to the eye following a single application in the New Zealand White rabbit. A volume of 0.1 ml of the test material was placed into the conjunctival sac of one eye of 3 animals. The other eye remained untreated and was used for control purposes. Assessment of ocular damage/irritation was made approximately 1 hour and 24, 48 and 72 hours following treatment. A single application of the test material to the non-irrigated eye of three rabbits produced no corneal effects, iridial inflammation was noted in one treated eye one hour after treatment only, with minimal to moderate conjunctival irritation noted in all treated eyes one hour after treatment with minimal conjunctival irritation noted in all treated eyes at the 24-hour observation. All treated eyes appeared normal at the 48-hour observation. Under the conditions of this study the test material is not considered to be irritating to the eye.