Trimethyl orthoacetate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1995-05-08 - 1995-05-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well-documented study conducted under GLP according to OECD guideline 405 on the registered substance itself without deviations.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Version / remarks:

OECD Guidelines for Testing of Chemicals, Section 4, No. 405, "Acute Eye Irritation/Corrosion" OECD 1992

Deviations:

not specified

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

EC Directive B.5. Acute toxicity (eye irritation); Appendix to Directive 92/69/EEC of the commission dated 31 July 1992 to the seventeenth amendment of Directive 67/548/EEC of the council for adaptation of the legal and administrative regulations for classification, packaging and labelling of hazardous substances to technical progress.

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Trimethyl orthoacetate

EC Number:

215-892-9

EC Name:

Trimethyl orthoacetate

Cas Number:

1445-45-0

Molecular formula:

C5H12O3

IUPAC Name:

1,1,1-trimethoxyethane

Test material form:

liquid

Details on test material:

- Substance type: pure substance
- Storage condition of test material: in a closed vessel under protective gas in a hood

Test animals / tissue source

Species:

rabbit

Strain:

other: small white Russian, Chbb:HM, SPF

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Bred by Dr Karl Thomae GmbH, Chemische-Pharmazeutische Fabrik, 88400 Biberach an der Riss 1, Germany
- Age at study initiation: healthy adult animals
- Weight at study initiation: Animal 1: 2.4 kg, Animal 2: 2.8 kg, Animal 3: 2.6 kg
- Housing: conventional, singly in stainless steel cages
- Diet (e.g. ad libitum): Ssniff K 4 complete feed for rabbits ad libitum, supplied by Ssniff, Spezialfutter GmbH, 59494 Soest, Germany. The manufacturer carries out regular tests on the feed.
- Water (e.g. ad libitum): Drinking water ad libitum, supplied by Gelsenwasser, Wasserwerk, 45721 Haltern, Germany. Samples of the tap water are tested in-house each quarter.
- Acclimation period: at least 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 3 °C
- Humidity (%): 30 - 70%
- Air changes (per hr): 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12-hour light/dark rhythm, artificial light

Test system

Vehicle:

unchanged (no vehicle)

Controls:

other: the untreated eye served as control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): single dose of 0.1 cm3 of the liquid

Duration of treatment / exposure:

24 h

Observation period (in vivo):

10 days after administration of the test substance
Reading time points: 1, 24, 48 and 72 hours and on days 6, 8 and 10 after administration of the test substance

Number of animals or in vitro replicates:

3 animals

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): rinsed with warm physiological saline
- Time after start of exposure: 24 h after administration

SCORING SYSTEM:
Cornea
Opacity: degree of density (most dense area taken for reading)
No ulceration or opacity: 0
Scattered or diffuse area of opacity (except slight clouding of the normal brightness), details of the iris clearly visible: 1
Easily discernible translucent area, details of iris slightly obscured: 2
Opalescent areas, no details of iris visible, size of pupil barely discernible: 3
Opaque cornea: iris invisible due to the opacity: 4

Iris
Normal: 0
Unusually deep folds, congestion, swelling, slight circumcorneal hyperaemia or injection; one of these symptoms or a combination of the various symptoms; iris still reacts to light (sluggish reaction is positive): 1
No reaction to light, haemorrhage, gross destruction (one or all of these symptoms): 2

Conjunctivae
Redness: (most pronounced finding on palpebral and bulbar conjunctivae compared with untreated eye)
Blood vessels normal: 0
Some blood vessels show distinct hyperaemia (injection): 1
Diffuse crimson red colour, individual vessels not easily discernible: 2
Diffuse beefy red: 3

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

TOOL USED TO ASSESS SCORE: fluorescein

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

conjunctivae score

Remarks:

conjunctival redness

Basis:

mean

Time point:

24/48/72 h

Score:

2.11

Max. score:

2.33

Reversibility:

fully reversible within: 10 days

Results 2

Irritation parameter:

chemosis score

Remarks:

Conjunctival swelling

Basis:

mean

Time point:

24/48/72 h

Score:

1.11

Max. score:

1.33

Reversibility:

fully reversible within: 10 days

Results 3

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Results 4

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0.89

Max. score:

1

Reversibility:

fully reversible within: 10 days

Irritant / corrosive response data:

In the test, all the animals showed pronounced defensive reactions on administration of TRIMETHYL ORTHOACETATE, and this was associated with vocalizations by one animal. One hour after administration, all the animals were found to have pronounced hyperaemia of some blood vessels, and conjunctival swelling was marked in two animals and slight in one animal. In addition, all the animals showed exudation and a decrease in the normal brightness of the cornea.
After 24 hours, the conjunctivae of the animals were a diffuse crimson red (some vessels were recognizable only with difficulty). This was associated with slight swelling in two animals and pronounced swelling in one animal. Slight corneal opacity was found in all the animals, while the fluorescein test showed clarification of more than one half and up to the entire surface. Two animals were still found to have exudation.
After 48 hours, the conjunctivae of two animals were found to have diffuse deep red discoloration together with bleeding, and one animal had diffuse crimson discolorations. The conjunctivae of all the animals were still slightly swollen. Exudation was found in one animal at this time. The cornea was slightly opaque in all the animals, and clarification ranged from spots up to 1/4 and, in one animal, up to the whole surface.
After 72 hours, the conjunctival discoloration in two animals had declined from diffuse deep red to diffuse crimson. One animal showed hyperaemia of some blood vessels. Two animals showed bleeding on the nictitating membrane and conjunctivae. Slight swelling was still found in all the animals. The cornea of two animals still showed slight opacity, with clarification of up to 1/4 of the surface, while there was no longer any corneal opacity in the third animal.
After 6 and 8 days there was still pronounced hyperaemia of some blood vessels in the conjunctivae of the three animals, and this was associated with slight swelling in one animal after 6 days. Two animals no longer had corneal opacity.
After 10 days, all the animals were free of signs of irritation of the eyes and mucosa.

Any other information on results incl. tables

The following averages were calculated from the individual scores assigned on inspection after 24, 48 and 72 hours: 

	Animal 1	Animal 2	Animal 3	Average
Conjunctival redness	1.67	2.33	2.33	2.11
Conjunctival swelling	1.00	1.33	1.00	1.11
Iris	0	0	0	0
Cornea	1.00	1.00	0.67	0.89

 

Individual findings 

Time after admin.	1 h			24 h			48 h			72 h
Animal	1	2	3	1	2	3	1	2	3	1	2	3
Conjunctival redness	1	1	1	2	2	2	2	3	3	1	2	2
Conjunctival chemosis	1	2	2	1	2	1	1	1	1	1	1	1
Iris	0	0	0	0	0	0	0	0	0	0	0	0
Cornea	0	0	0	1	1	1	1	1	1	1	1	0
Fluorescein test*	-	-	-	3	4	4	1	1	4	1	1	0
Exudation	x	x	x		x	x		x
Conjunctivae incl. lids and nictitating membrane with bleading								x	x		x	x
Cornea: Decrease in normal brightness	x	x	x
Iris: Circumcorneal hyparaemia
Iris: Circumcorneal injection

 Individual findings (continued)

Time after admin.	6 d			8 d			10 d
Animal	1	2	3	1	2	3	1	2	3
Conjunctival redness	1	1	1	1	1	1	0	0	0
Conjunctival chemosis	0	1	0	0	0	0	0	0	0
Iris	0	0	0	0	0	0	0	0	0
Cornea	0	0	0	0	0	0	0	0	0
Fluorescein test*	0	0	0	-	-	-	-	-	-
Exudation
Conjunctivae incl. lids and nictitating membrane with bleading
Cornea: Decrease in normal brightness
Iris: Circumcorneal hyparaemia
Iris: Circumcorneal injection

 * the area of clarification of the corneal surface after instillation of one drop of fluorescein Na (0.1%) is stated:

0= no clarification, 1 = spots up to 1/4, 2 = more than 1/4 to 1/2, 3 = more than 1/2 to 3/4, 4 = more than 3/4 to 4/4

 

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

The study was performed according to the OECD TG405 without deviations and according to the good laboratory practice principles. Therefore, the study is considered to be of the highest quality (reliability Klimisch 1). The validity criteria of the test system are fulfilled. The test material induced reversible irritation on rabbit eyes. Accordingly, the test material Trimethyl orthoacetate (TMOA) was classified as irritating to the eyes (Category 2).

Executive summary:

The test substance Trimethyl orthoacetate (TMOA) was investigated for its potential to cause irritation in the rabbit eye and mucosa according to OECD TG 405 ("Acute Eye Irritation/Corrosion" (adopted 24 February 1987) and Method B5 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC)

0.1 ml of the liquid test substance was administered into the conjunctival sac of one eye of each of three male rabbits, the untreated eye served as control. After exposure for 24 hours, the eyes were washed out with warm physiological saline. Under the conditions of this experiment the test compound was found to cause irritation, when applied to the rabbit eye. After 10 days, the eyes and mucosa of all the animals were free of signs of irritation.

Accordingly, the test material meets the criteria for classification as irritating to eyes (Category 2) according to EU labelling regulations.