Purine-2(3H),6(1H)-dione

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The test item solubility was tested in acetonitrile, water, 1: 1 (v:v) acetonitrile:water, isopropanol, methanol, ethanol, 1,4-butandiol, N,N-dimethylformamide (DMF) and tertbutanol at 100 mM. The test item was not soluble in any of these solvents. Therefore, in vitro studies could not be performed.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2500 (Acute Dermal Irritation)

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: JMAFF 12-Nousan-8147

Version / remarks:

2000

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Purine-2(3H),6(1H)-dione

EC Number:

200-718-6

EC Name:

Purine-2(3H),6(1H)-dione

Cas Number:

69-89-6

Molecular formula:

C5H4N4O2

IUPAC Name:

xanthine

Specific details on test material used for the study:

Purity: > 99% purity

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: Young adult (12-13 weeks)
- Weight at study initiation: 2517.2- 2726.9 grams
- Housing: Individually housed in suspended stainless steel caging.
- Diet: PMI 5326 High Fiber Rabbit Diet; designated amount of diet (approximately 150 grams/day) and alfalfa hay cubes (Grainland Select Alfalfa Cubes) available to each rabbit.
- Water: ad libitum
- Acclimation period: 8 or 14 days
- Other: Elizabethan collars placed on rabbits after removal of patches.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-24ºC (Temperature was below the targeted lower limit for eight days during the study. These excursions were considered minor and had no impact on this study.)
- Humidity (%): 53-80%, (Humidity was above the targeted upper limit for one day during the study. A portable dehumidifier was used to lower the humidity levels during this time. These excursions were considered minor and had no impact on this study.
- Air changes (per hr): 12
- Photoperiod (hrs dark/ hrs light): 12-hour light/dark cycle

Test system

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

water

Remarks:

test substance applied as a dry paste (70% w/w mixture in distilled water).

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.71 g of test mixture

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Stored at room temperature.
- 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.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing (e.g. warming, grinding): To ensure adequate contact with skin, test substance was applied as dry paste (70% w/w mixture in distilled water).
- Preliminary Toxicity Testing: Initial testing conducted on one rabbit to determine irritation/corrosion potential of test substance. Three dose sites, each approximately 6-cm2, were delineated on rabbit. Five-tenths of a gram of test substance (0.71 g of test material) was placed on 1-inch x 1-inch, 4-ply gauze pad and applied to each dose site. Pads and entire trunk of animal were wrapped with semi-occlusive tape. After removal of 3-minute patch, rabbit returned to designated cage. Pads were removed at appropriate intervals (3 minutes, 1 hour, and 4 hours). All dose sites were evaluated for corrosion 30-60 minutes after patch removal. Subsequent evaluations were performed approximately 24, 48, and 72 hours after removal of four-hour patch. Since there was no corrosion observed at any of dose sites for this animal, two additional rabbits (each with one patch only for a 4-hour exposure period), were selected for further testing and treated in same manner.

Duration of treatment / exposure:

3 minutes, 1 hour, or 4 hours

Observation period:

30-60 minutes after patch removal (all exposures) and 24, 48, and 72 hours after patch removal (4-hour exposure)

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: Approximately 6 cm2
- Coverage: Five-tenths of a gram of test substance (0.71 g of the test mixture) placed on gauze and applied to each dose site.
- Type of wrap if used: Pads and entire trunk of animal wrapped with semi-occlusive 3-inch tape to avoid dislocation of patches.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Cleansed with a 3% soap solution followed by tap water and a clean paper towel to remove any residual test substance.
- Time after start of exposure: After the 3-minute, 1-hour, and 4-hour exposure periods.

OBSERVATION TIME POINTS
24-, 48-, and 72-hour observation time points

SCORING SYSTEM:
- Method of calculation: Individual dose sites were scored according to the Draize scoring system immediately following patch removal (initial rabbit only) and at approximately 30-60 minutes, 24, 48, and 72 hours after patch removal in addition to evaluation for corrosion at these intervals for the first animal only. Mean values for each lesion (erythema and edema) were calculated for each animal separately from numerical scores obtained at the 24-, 48-, and 72-hour observations.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

edema score

Remarks:

(mean score for dermal response)

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Remarks on result:

no indication of irritation

Results 2

Irritation parameter:

edema score

Remarks:

(mean score for dermal response)

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Remarks on result:

no indication of irritation

Results 3

Irritation parameter:

edema score

Remarks:

(mean score for dermal response)

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Remarks on result:

no indication of irritation

Results 4

Irritation parameter:

erythema score

Remarks:

(mean score for dermal response)

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Remarks on result:

no indication of irritation

Results 5

Irritation parameter:

erythema score

Remarks:

(mean score for dermal response)

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Remarks on result:

no indication of irritation

Results 6

Irritation parameter:

erythema score

Remarks:

(mean score for dermal response)

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Remarks on result:

no indication of 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. No dermal irritation was noted at the 3-minute exposure site for first animal. In one animal, within 30-60 minutes of patch removal, very slight erythema (score of 1) and very slight edema (score of 1) was noted at 1-hour exposure site, which resolved by 24 hours. One animal exhibited very slight erythema (score of 1) within 30-60 minutes of patch removal after 4-hour exposure, which resolved by 24 hours.

Other effects:

In-Life Observations: While some minimal weight loss was observed, all animals stayed active and healthy throughout study.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

No visible necrosis (corrosion) was observed. Very slight irritation which resolved by 24 hours was observed. The test substance is not a skin irritant.

Executive summary:

A primary skin irritation test was conducted with rabbits to determine the potential for the test substance to produce irritation after a single topical application. 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 Micropore 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 and for corrosion 30-60 minutes after the appropriate patch removal. 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. No dermal irritation was noted at the 3-minute exposure site for the first animal. Within 30-60 minutes of patch removal, very slight erythema and very slight edema was noted at the exposure site in one animal, which resolved by 24 hours. Within 30-60 minutes of patch removal, one treated site exhibited very slight erythema, which resolved by 24 hours. The test substance is not a skin irritant.