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

Skin irritation / corrosion

Administrative data

Endpoint:

skin 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 404 (Acute Dermal Irritation / Corrosion)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected August 2005; signature: November 2005

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

482-180-4

EC Name:

-

IUPAC Name:

482-180-4

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

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

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

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

Test system

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5mL
- Concentration (if solution): Test material was used as supplied.

Duration of treatment / exposure:

4 hours

Observation period:

72 hours

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: dorsal
- Type of wrap if used: semi-occlusive

REMOVAL OF TEST SUBSTANCE
- Washing (if done): yes, Four hours after application the corset and patches were removed from each animal and any residual test material removed by gentle swabbing with cotton wool soaked in distilled water.
- Time after start of exposure: 4 hours

SCORING SYSTEM:
Erythema and Eschar Formation
No erythema ................. ....... ... ...... ... ........ .... .. ... .... ..... ..... ...... ...... ... .......... ........... .. .. .0
Very slight erythema (barely perceptible) ... .................... .. .... ....... .......... .. .................... .1
Well-defined erythema .............. ....... .. .................. ....... ... .. ... .... .... ........... ... ............ .... ..2
Moderate to severe erythema ............... ... .. .................. .... .... ...... .... ........... ... ............ .....3
Severe erythema (beet redness) to slight eschar formation (injuries in depth) .. .. ........4

Oedema Formation
No oedema ... .......................... ....... ........ .. ..... ... ......... ...... .. ......... .. ............... .. ... ... .... .... ... .0
Very slight oedema (barely perceptible) ........ .. ...... ............ .... .. ...... ... .. .... ... ........... .... .. .. .1
Slight oedema (edges of area well-defined by definite raising) .......... ....... ... .......... .. .... ......2
Moderate oedema (raised approximately 1 millimetre) ............... ............................ .... ............3
Severe oedema (raised more than 1 millimetre and extending beyond the area of
exposure) ........................ ... .... .. ..... .. ... ................... .... ................... ...... .. .. .. ........... ... ... ..... .4

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 1h

Score:

1

Max. score:

4

Reversibility:

fully reversible

Results 2

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 24h

Score:

1.67

Max. score:

4

Reversibility:

fully reversible

Remarks on result:

other: reaction extended 4 cm beyond treatment site in 2/3 organisms

Results 3

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 48h

Score:

1.67

Max. score:

4

Reversibility:

fully reversible

Remarks on result:

other: reaction extended 4 cm beyond treatment site in 2/3 organisms

Results 4

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 72h

Score:

1.67

Max. score:

4

Reversibility:

fully reversible

Remarks on result:

other: reaction extended 4 cm beyond treatment site and reported loss of skin elasticity in 2/3 organisms

Results 5

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 7 day

Score:

0

Max. score:

4

Reversibility:

fully reversible

Remarks on result:

other: Crust formation in 2/3 organisms

Results 6

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 14 day

Score:

0

Max. score:

4

Reversibility:

fully reversible

Remarks on result:

other: No effects reported at 14d

Results 7

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 1h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Results 8

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 24h

Score:

1

Max. score:

4

Reversibility:

fully reversible

Results 9

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 48h

Score:

1

Max. score:

4

Reversibility:

fully reversible

Results 10

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 72h

Score:

0.67

Max. score:

4

Reversibility:

fully reversible

Results 11

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 7 day

Score:

0

Max. score:

4

Reversibility:

fully reversible

Results 12

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 14 day

Score:

0

Max. score:

4

Reversibility:

fully reversible

Remarks on result:

other: No effects reported at 14d

Irritant / corrosive response data:

- Erythema: Very slight erythema was noted at all treated skin sites one hour after patch removal with very slight to well-defined erythema noted at all treated skin sites at the 24, 48 and 72-hour observations. The erythematous reaction extended approximately 4 cm beyond the treatment sites of two animals at the 24, 48 and 72-hour observations.

- Oedema: Very slight oedema was noted at all treated skin sites at the 24 and 48-hour observations and at two treated skin sites at the 72-hour observation. Loss of skin elasticity was noted at two treated skin sites at the 72-hour observation with crust formation noted at these two treated skin sites at the 7 -day observation.

- Reversibility of effects: One treated skin site appeared normal at the 7 -day observation and the remaining two treated skin sites appeared normal at the 14-day observation.

Any other information on results incl. tables

Table 1. Individual skin reactions

Skin Reaction	Observation Time	Individual Scores
		1 (male)	2 (male)	3 (male)
Erythema/Eschar formation	1 hour	1	1	1
	24 hours	1	2 R	2 R
	48 hours	1	2 R	2 R
	72 hours	1	2 RLe	2 RLe
	7 days	0	0 Cf	0 Cf
	14 days	0	0	0
Oedema formation	1 hour	0	0	0
	24 hours	1	1	1
	48 hours	1	1	1
	72 hours	0	1	1
	7 days	0	0	0
	14 days	0	0	0

Cf = crust formation

Le = Loss of skin elasticity

R = Erythematous reaction extends 4 cm beyond the treatment site

 

Mean scores per organism at 24, 48 and 72h:

Erythemea/Escar Formation:

1: total = 3; mean score = 1.0

2: total = 6; mean score = 2.0

3: total = 6; mean score = 2.0

Oedema Formation:

1: total = 2; mean score = 0.7

2. total = 3; mean score = 1.0

3. total = 3; mean score = 1.0

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 considered to be irritating.

Executive summary:

The study was performed to EU Method B.4 and OECD 404 to assess the primary skin irritancy potential of the test substance in accordance with GLP in New Zealand White rabbits. 0.5 ml of the test material was introduced under a 2.5 cm x 2.5 cm cotton gauze patch and placed in position on the shorn skin. The patch was secured in position with a strip of surgical adhesive tape. To prevent the animals interfering with the patches, the trunk of each rabbit was wrapped in an elasticated corset and the animals were returned to their cages for the duration of the exposure period. After 4 hours of exposure to the test substance, the pads and collars were removed and the test sites were gently cleaned of any residual test substance with distilled water. Individual dose sites were scored according to the Draize scoring system at approximately 1, 24, 48, and 72 hours, 7 and 14 days after patch removal. Very slight erythema was noted at all treated skin sites one hour after patch removal with very slight to well-defined erythema noted at all treated skin sites at the 24, 48 and 72-hour observations which extended beyond the treatment area. Very slight oedema was noted at all treated skin sites at the 24 and 48-hour observations and at two treated skin sites at the 72-hour observation. Loss of skin elasticity was noted at two treated skin sites at the 72-hour observation with crust formation noted at these two treated skin sites at the 7 -day observation. One treated skin site appeared normal at the 7 -day observation and the remaining two treated skin sites appeared normal at the 14-day observation. Based on the applicant's recalculation of the mean scores following grading at 24, 48 and 72h, the mean scores did not meet the EU classification criteria under Regulation (EC) 1272/2008. The substance has the potential to produce mild transient skin irritation but is insufficient for classification. The substance cannot be considered a skin irritant.