Methyl 2,6,6-trimethylcyclohex-2-ene-1-carboxylate

Endpoint summary

Description of key information

Skin irritation: non-irritating, eq. or sim. to OECD TG 404, 1981

Eye irritation: non-irritating, eq. or sim. to OECD TG 405, 1981

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1981

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study following a method equivalent to a recognised OECD guideline. Deviations to recognised guideline are noted.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

Occlusive dressing smaller exposure area (ca. 2.5cm2), longer exposure period (24h) shorter observation period (48h)

Qualifier:

according to guideline

Guideline:

other: 16 CFR 1500.41

Deviations:

no

Principles of method if other than guideline:

The method was in accordance with the 16 CFR 1500.41 and US CPSC requirements

GLP compliance:

yes

Species:

rabbit

Strain:

other: albino; not otherwise specified

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Recognised animal supplier
- Age at study initiation: Not reported.
- Weight at study initiation: Not reported.
- Housing: Not reported but in compliance with Animal Welfare Act (Pub. L-94-279) 9 CFR Part 3 (USA).
- Diet: rabbit chow ad libitum
- Water: ad libitum
- Acclimation period: Not reported.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Not reported.
- Humidity (%): Not reported.
- Air changes (per hr): Not reported.
- Photoperiod (hrs dark / hrs light): Not reported.

Type of coverage:

occlusive

Preparation of test site:

other: clipped / abraded

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 ml
- Concentration (if solution): neat (liquid)

Duration of treatment / exposure:

24 hours

Observation period:

72 hours

Number of animals:

6 (sexes not specified)

Details on study design:

TEST SITE
- Area of exposure: According to 16 CFR 1500.41
- % coverage: Not reported. A group of six albino rabbits was clipped over a wide area. One side of the animals' backs was abraded at one site with a lancet sufficiently deep to penetrate the stratum corneum but not enter the derma to produce bleeding. The skin of the other side was allowed to remain intact.
- Type of wrap if used: Occlusive (gauze wrapped with impervious material)

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Not reported
- Time after start of exposure: Not applicable.

SCORING SYSTEM: Draize-scoring system. References: 16 CFR 1500.41 and 16 CFR 1500.3.

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

mean

Time point:

other: mean of 24 and 72 h

Score:

0

Max. score:

8

Remarks on result:

other: intact and abraded skin

Irritant / corrosive response data:

Intact skin: No edema and no erythema responses were observed in any animal at any observation point.

Table 1. Skin reactions (using Draize scoring method)

Erythema & Eschar Formation	Hours	Rabbit number						Mean score
		1	2	3	4	5	6
Intact skin	24	0	0	0	0	0	0	0.00
	72	0	0	0	0	0	0	0.00
Abraded skin	24	0	0	0	0	0	0	0.00
	72	0	0	0	0	0	0	0.00
Edema
Intact skin	24	0	0	0	0	0	0	0.00
	72	0	0	0	0	0	0	0.00
Abraded skin	24	0	0	0	0	0	0	0.00
	72	0	0	0	0	0	0	0.00
Sum of mean scores								0.00
Primary irritation index = sum of mean scores/4								0.00

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: US CPSC / US FDA

Conclusions:

Under the conditions of this study the test substance is not considered to be irritating to the skin.

Executive summary:

The GLP study was completed under 16 CFR 1500.41 following a guideline similar to OECD 404, to assess the irritancy potential of the test material to the skin of the albino rabbit. The test substance was evaluated in 6 albino rabbits. A dose of 0.5 ml test substance was applied to intact and abraded clipped dorsal skin site under a occlusive dressing for 24 hours. Skin observations were made 24 and 72 hours after patch removal. No edema or erythema responses were noted (Score = 0) at 24 or 72 hours in the intact and/or the abraded skin in all organisms. The test material produced a mean primary irritation index (PII) of 0.00 and is considered to be non-irritating to skin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1981

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study following a method equivalent to a recognised guideline.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: 16 CFR 1500.42

Deviations:

no

Principles of method if other than guideline:

The method was in accordance with the 16 CFR 1500.42 and US CPSC requirements

GLP compliance:

yes

Species:

rabbit

Strain:

other: albino ; not otherwise specified

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Recognised supplier.
- Age at study initiation: Young adults.

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 grammes
- Concentration (if solution): neat (unchanged)

Duration of treatment / exposure:

3 days

Observation period (in vivo):

4 days (observations were completed every day from day 1 to day 7 post treatment).

Number of animals or in vitro replicates:

6 (sexes not specified)

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): No.

SCORING SYSTEM: Draize scoring system. Reference 16 CFR 1500.42.

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

24

Remarks on result:

other: n = 6; maximum category score = 4

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

7 d

Score:

0

Max. score:

24

Remarks on result:

other: n = 6; maximum category score = 4

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

12

Remarks on result:

other: n =6; maximum category score = 2

Irritation parameter:

iris score

Basis:

mean

Time point:

7 d

Score:

0

Max. score:

12

Remarks on result:

other: n =6 ; maximum category score = 2

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

18

Remarks on result:

other: n =6 ; maximum category score = 3; conjunctivae redness - maximum score = 0

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

7 d

Score:

0

Max. score:

18

Remarks on result:

other: n =6 ; maximum category score = 3

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

24

Remarks on result:

other: n =6 ; maximum category score = 4; chemosis - maximum score = 0

Irritation parameter:

chemosis score

Basis:

mean

Time point:

7 d

Score:

0

Max. score:

24

Remarks on result:

other: n =6 ; maximum category score = 4; chemosis - maximum score = 0

Irritant / corrosive response data:

Following scoring at 24, 48 and 72 h: No positive corneal scores. No positive iridal scores. No positive conjunctivae redness mean scores. No positive chemosis mean scores. All scores for all effect categories were < 1 in all animals on all days (24 to 72hs; and up to 7 days). Discharge positive scores were also absent.

Individual scoring data was presented within the study report. No positive responses observed.

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: US CPSC / US FDA

Conclusions:

Under the conditions of this study the test substance would not be considered as an eye irritant.

Executive summary:

The GLP study was completed under 16 CFR 1500.42 following a guideline similar to OECD 405, to assess the irritancy potential of the test material to the eye following a single application in the albino rabbit. A mass of 0.1 grams of the test material was placed into one eye in each of 6 animals. The other eye remained untreated and was used for control purposes. Assessment of ocular damage/irritation was made approximately 24, 48 and 72 hours following treatment with observations daily up to 7 days. No corneal opacity or iritis, chemosis or conjunctival redness as observed at any time point up to 7 days in all animals. Under the conditions of this study the test material is not considered to be an eye irritant.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation:

The GLP study was completed under 16 CFR 1500.41 following a guideline similar to OECD 404, to assess the irritancy potential of the test material to the skin of the albino rabbit. The test substance was evaluated in 6 albino rabbits. A dose of 0.5 ml test substance was applied to intact and abraded clipped dorsal skin site under a occlusive dressing for 24 hours. Skin observations were made 24 and 72 hours after patch removal. No edema or erythema responses were noted (Score = 0) at 24 or 72 hours in the intact and/or the abraded skin in all organisms. The test material produced a mean primary irritation index (PII) of 0.00 and is considered to be non-irritating to skin.

 

The mean score at 24 and 72h of intact skin was < 2.3 in all organisms in all response criteria (erythma/escar or edema) and any effects did not persist to the end of the observation period (72h). Since four or more organisms did not demonstrate a mean score greater than or equal to 2.3 ; there was an absence of reported significant dermal effects (e.g. alopecia, hyperplasia or scaling) and/or significant variability of responses, the substance is not considered to be irritating. The substance is not irritating to the skin. Further testing for skin irritation is unjustified.

 

Eye irritation/corrosion:

The GLP study was completed under 16 CFR 1500.42 following a guideline similar to OECD 405, to assess the irritancy potential of the test material to the eye following a single application in the albino rabbit. A mass of 0.1 grams of the test material was placed into one eye in each of 6 animals. The other eye remained untreated and was used for control purposes. Assessment of ocular damage/irritation was made approximately 24, 48 and 72 hours following treatment with observations daily up to 7 days. No corneal opacity or iritis, chemosis or conjunctival redness as observed at any time point up to 7 days in all animals. Under the conditions of this study the test material is not considered to be an eye irritant. Based on the applicants evaluation and/or recalculation of the mean scores the test material is not considered to be irritating to the eye under Regulation (EC) 1272/2008 criteria due to a complete absence of Corneal Opacity and Corneal Iritis indicative of full reversibility within 21-days. Redness and Chemosis scores were also absent. There was additionally an absence of significant variation of responses.

Justification for selection of skin irritation / corrosion endpoint:

one in vivo GLP compliant Klimisch 1 study; applicant evaluated and/or recalculated the mean and individual scoring in concluding the endpoint where necessary.

Justification for selection of eye irritation endpoint:

one in vivo GLP compliant Klimisch 1 study; applicant evaluated and/or recalculated the mean and individual scoring in concluding the endpoint where necessary.

Justification for classification or non-classification

The substance does not meet classification criteria under Regulation (EC) No 1272/2008 for dermal irritation.

 

The substance does not meet classification criteria under Regulation (EC) No 1272/2008 for eye irritation.

 

For skin irritation, the weight of evidence indicates that the substance has the potential to be slightly irritating however this is not sufficient for classification purposes. Available data indicates negative irritation in an in vivo dermal irritation study. This study utilised occlusive dressings (increases percutaneous absorption; potential altering of epidermal lipids, DNA synthesis, epidermal turnover, pH, epidermal morphology) resulting in a predisposition towards positive and irreversible irritation. This is absent however. The overall evidence by expert judgement indicates that the substance may produce transient and very slight to non-existent irritation by the dermal route which is not sufficient for classification in accordance with the above criteria.

 

For eye irritation, the weight of evidence indicates that the substance has the potential to cause transient very mild to non-existent irritating effects to the eye; which are insufficient for classification based on the applicants recalculation of the mean scoring and evaluation of the results in six organisms demonstrating that the EU criteria had not been met. Effects in vivo on corneal opacity and iritis are non-existent and conjunctival effects are additionally absent out to 7 days of observation; the overall evidence is indicative of transient and reversible effects on the eye.

 

References:

1. Guidance on Application of the CLP Criteria, ECHA, version 5.0 – June 2017.