((4S,4aR,7S,7aR)-4,7-dimethylhexahydrocyclopenta[c]pyran-1(3H)-one

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 19 to June 3, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 001

Cas Number:

N/A

Molecular formula:

C10H16O2

Test material form:

liquid

Remarks:

Colorless

Details on test material:

Test substance was expected to be stable for the duration of testing.

Specific details on test material used for the study:

- lot number of test material:
CH-DA-01-18

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:
Stored refrigerated

- Stability and homogeneity of the test material in the vehicle/solvent under test conditions (e.g. in the exposure medium) and during storage:
Test substance was expected to be stable for the duration of testing.

- Stability in the medium, i.e. sensitivity of the test material to hydrolysis and/or photolysis:
The test substance was applied as received

- Solubility and stability of the test material in the solvent/vehicle and the exposure medium:
The test substance was applied as received

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing (e.g. warming, grinding):
Mixed well prior to use

- Preliminary purification step (if any):
None

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Robinson Services, Inc.
- Age at study initiation: 14 weeks
- Weight at study initiation: 2584-2870 grams
- Housing:
The animals were singly housed in suspended stainless steel caging, which conforms to the size recommendations in the most recent Guidefor the Care and Use ofLaboratory Animals (Natl. Res. Council, 2011). Enrichment (e.g., toy) was placed in each cage. Litter paper was placed beneath the cage and was changed at least three times per week.

- Diet (e.g. ad libitum):
PMI 5326 High Fiber Rabbit Diet. A designated amount of the diet (approximately 150 grams/day) and alfalfa hay cubes (Grainland Select Alfalfa Cubes) were available to each rabbit.

- Water: Filtered tap water was supplied ad libitum

- Acclimation period: 14 or 20 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 24
- Humidity (%): 49 - 70
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12

Test system

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

Five-tenths of a millilitre

Duration of treatment / exposure:

3 minutes, 1 hour, and 4 hours

Observation period:

All dose sites were evaluated for corrosion 30-60 minutes after patch removal. Subsequent evaluations were performed approximately 24, 48, 72 hours and at 7 days after removal of the four-hour patch.

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: 6 Cm2
- coverage: 1-inch x 1-inch, 4-ply gauze pad.
- Type of wrap if used: semi-occlusive 3-inch Micropore tape

REMOVAL OF TEST SUBSTANCE
- Washing (if done): 3% soap solution followed by tap water and a clean paper towel
- Time after start of exposure: 3 minutes, 1 hour, and 4 hours

OBSERVATION TIME POINTS
30-60 minutes; 24, 48, 72 hours and at 7 days

SCORING SYSTEM:
- Method of calculation: Draize scoring system

Results and discussion

In vivo

Results

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

mean

Remarks:

Average values for three rabbits.

Time point:

other: 30-60 minutes; 24, 48 and 72 hours

Score:

1.7

Reversibility:

fully reversible

Remarks:

All animals were free of dermal irritation by Day 7 (study termination).

Remarks on result:

probability of mild irritation

Irritant / corrosive response data:

No visible necrosis (corrosion) of the skin tissue was observed at the 3-minute, 1-hour and 4-hour
dose sites during the study. In the 3-minute exposure site, within 30-60 minutes of patch removal, very slight erythema was noted at the 3-minute exposure site, which resolved by 24 hours.


In 1 hour exposure site, within 30-60 minutes of patch removal, very slight erythema was noted at the 1-hour exposure site. The overall incidence and severity of irritation decreased with time. Dermal irritation cleared from the treated site by 48 hours.


In 4 hours exposure sites, over the first 72 hours after patch removal, all three treated sites exhibited very slight to well-defined erythema and/or very slight edema. The overall incidence and severity of irritation decreased gradually with time. All animals were free of dermal irritation by Day 7 (study termination).


The Primary Dermal Irritation Index for Dihydronepetalactone was 1.7.

Any other information on results incl. tables

INDIVIDUAL SKIN IRRITATION SCORES

3-MINUTE EXPOSURE

Animal No	Sex	Time after removal of patch
		Minute	Hours			Days
		30 - 60	24	48	72	7
3501	F	1/0	0/0	0/0	0/0	0/0

 

1-HOUR EXPOSURE

Animal No	Sex	Time after removal of patch
		Minute	Hours			Days
		30 - 60	24	48	72	7
3501	F	1/0	1/0	0/0	0/0	0/0

 

4-HOUR EXPOSURE

Animal No	Sex	Time after removal of patch
		Minute	Hours			Days
		30 - 60	24	48	72	7
3501	F	1/0	2/0	2/0	2/0	0/0
3502	F	1/0	2/0	1/0	1/0	0/0
3503	F	1/1	2/1	1/1	1/1	0/0
Total		3/1	6/1	4/1	4/1	0/0
Mean		1.0/0.3	2.0/0.3	1.3/0.3	1.3/0.3	0/0

Applicant's summary and conclusion

Interpretation of results:

Category 3 (mild irritant) based on GHS criteria

Conclusions:

Mildly irritating according to GHS (8th revised edition)

Executive summary:

A primary skin irritation test was conducted with rabbits to determine the potential for Dihydronepetalactone to produce irritation after a single topical application. Under the conditions of this study, the test substance is classified as slightly irritating to the skin.

Initially, one rabbit was tested to determine the irritation/corrosion potential of the test substance. Three dose sites, each approximately 6-cm2, were delineated on this animal. Five-tenths of a milliliter of the neat test substance was applied to the skin of each dose site. The pads and entire trunk of the animal were then wrapped with semi-occlusive 3-inch MicroporeTM tape to avoid dislocation of the patches. The patches were removed at the appropriate intervals (3 minutes, 1 hour, and 4 hours). All dose sites were evaluated for skin irritation according to the Draize method of scoring (Draize et al., 1944; see Table 6) and for corrosion 30-60 minutes after the appropriate patch removal. Subsequent evaluations were performed approximately 24, 48, 72 hours and at 7 days after removal of the 4-hour patch. Since there was no corrosion observed at any of the dose sites for this animal, two additional rabbits were selected for testing and had the test substance applied for 4 hours only. All dose sites were evaluated for skin irritation according to the Draize scoring system at 30-60 minutes, and 24, 48, 72 hours and at 7 days after patch removal.

No visible necrosis (corrosion) of the skin tissue was observed at the 3-minute, 1-hour and 4-hour dose sites during the study.

3-Minute Exposure Site: Within 30-60 minutes of patch removal, very slight erythema was noted at the 3-minute exposure site, which resolved by 24 hours.

1-Hour Exposure Site: Within 30-60 minutes of patch removal, very slight erythema was noted at the 1-hour exposure site. The overall incidence and severity of irritation decreased with time. Dermal irritation cleared from the treated site by 48 hours.

4-Hour Exposure Site: Over the first 72 hours after patch removal, all three treated sites exhibited very slight to well-defined erythema and/or very slight edema. The overall incidence and severity of irritation decreased gradually with time. All animals were free of dermal irritation by Day 7 (study termination).

The Primary Dermal Irritation Index (PDII) calculated for this test substance was 1.7. The test substance is Mildly irritating according to GHS (8th revised edition).