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Toxicological information

Skin irritation / corrosion

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Administrative data

skin irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study conducted according to generally accepted methods (similar to OECD Guideline 404) for a dermal irritation study.
Justification for type of information:
A discussion and report on the read across strategy is given as an attachment in Section 13.
Reason / purpose for cross-reference:
read-across: supporting information

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
abraded and intact skin sites were exposed for 24 hours rather than a 4-hour exposure to intact skin as recommended in the guideline
GLP compliance:

Test material

Constituent 1
Reference substance name:
Rosin, reaction products with formaldehyde
EC Number:
EC Name:
Rosin, reaction products with formaldehyde
Details on test material:
-Identity (according to study report): UNITAC 70
-FDRL Test Article ID: 85-0693
-Physical state: Solid

Test animals

New Zealand White
Details on test animals or test system and environmental conditions:
-Source: Ace Animals, Inc., Boyertown, PA, USA
-Number of animals: 6 (2 males and 4 females)
-Age: young adults
-Acclimation period: at least 5 days
-Weight at study initiation: 2.19-2.77 kg
-Housing: individually in wire mesh bottom cages
-Diet: NIH 09 Rabbit Ration, supplied by Zeigler Brothers, Gardners, PA, USA, available ad libitum
-Water: available ad libitum
-Identification: ear tags and color-coded cage cards

-Housed in environmentally-controlled rooms
-All housing and care conformed to the standards established in the "Guide for the Care and Use of Laboratory Animals" DHEW Publication No. (NIH) 85-23.

-Date of study initiation: 1985-09-26
-Date of study termination: 1985-09-29

Test system

Type of coverage:
Preparation of test site:
other: shaved, abraded, and intact
unchanged (no vehicle)
not required
Amount / concentration applied:
0.5 g of test material moistened with 0.5 mL of physiological saline; applied to two sites (one intact, one abraded) per rabbit
Duration of treatment / exposure:
24 hours
Observation period:
72 hours post-treatment
Number of animals:
Details on study design:
-Test site preparation:
On the day prior to dosing, the dorsal surface of each rabbit was clipped. Prior to application of the test substance, the application site on the right dorsal side was abraded with a hypodermic needle. The abrasions were made in a cross hatch pattern which penetrated the stratum corneum but did not disturb the dermis or produce bleeding. The left dorsal side was not abraded.

-Test material preparation:
The test material was ground with a mortar and pestle, then dispensed as an undiluted powder.

-Test material administration:
The test substance (0.5 g) was moistened with 0.5 mL physiological saline and applied to each of two application sites (one abraded and one intact) per rabbit. Following application, each test site was occluded with a one-inch square gauze patch and tape. The trunk of each animal was then wrapped with an occlusive binder.

-Test material exposure:
The test material was kept in contact with the skin for a period of 24 hours, at which time the wrappings were removed and any residual test material was removed by gentle wiping with clean gauze.

The application sites were scored for dermal irritation at 30 minutes after removal of the wrappings, and again at 72 hours post-treatment. Both application sites of each rabbit were scored separately for erythema and edema on a graded scale of 0-4 as described in Draize (1944) and listed below:

Erythema and eschar formation:
0 - No erythema
1 - Very slight erythema (barely perceptible)
2 - Well-defined erythema
3 - Moderate to severe erythema
4 - Severe erythema (beet red) to slight eschar formations (injuries in depth)

Edema formation:
0 - No edema
1 - Very slight edema (barely perceptible)
2 - Slight edema (edges of area well defined by definite raising)
3 - Moderate edema (raised approximately 1 mm)
4 - Severe edema (raised more than 1 mm and extending beyond the area of exposure)

-Data evaluation:
In evaluating the average irritation, individual scores for intact and abraded sites were recorded separately for each of the two scoring time intervals. The total for erythema was added to the total for edema then divided by 4 to yield the individual animal score. The mean of the six scores was calculated and this score represented the mean primary irritation score.

-Body weights:
Body weights were recorded prior to administration of the test substance. Body weights were not recorded at study termination.

Draize JH, Woodard G & Calvery HO. 1944. Methods for the Study of Irritation and Toxicity of Substances Applied Topically to the Skin and Mucous Membranes. J. Pharmacol. Exp. Ther. 377-390.

Results and discussion

In vivo

Resultsopen allclose all
Irritation parameter:
primary dermal irritation index (PDII)
Time point:
other: 24.5 and 72 hours post-dose
Max. score:
other: No signs of irritation were evident during the test.
Irritation parameter:
erythema score
animal: 1-6
Time point:
24/48/72 h
Remarks on result:
other: Individual animal scores not provided; only mean scores available
Irritation parameter:
edema score
animal: 1-6
Time point:
24/48/72 h
Remarks on result:
other: Individual animal scores not provided; only mean scores available
Irritant / corrosive response data:
For the abraded and intact skin sites, no signs of erythema or edema were evident during the study in any of the 6 rabbits.
Other effects:
There were no abnormal systemic signs noted during the observation period.

Any other information on results incl. tables

Both the abraded site and the intact site on each of the six rabbits were graded as "0" for erythema and "0" for edema at all observation periods.

Applicant's summary and conclusion

Interpretation of results:
other: Not irritating
Criteria used for interpretation of results: EU
Rosin, reaction products with formaldehyde (CAS No. 91081-53-7) is not a primary skin irritant when tested using a method similar to that described in OECD Guideline 404. No signs of erythema or edema were observed on rabbit skin when the test material was applied to intact and abraded skin under occluded contact for twenty-four hours.

Rosin, reaction products with formaldehyde (CAS No. 91081-53-7) is not classified for corrosion/ irritation in Annex I of Directive 67/548/EEC. Based on the absence of any signs of irritation during the study, this material is not classifiable for skin irritation according to UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS) or EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.
Executive summary:

In a primary dermal irritation study, six young adult New Zealand white rabbits (2 males, 4 females) were exposed to 0.5 g of UNITAC 70 (rosin, reaction products with formaldehyde) applied for 24 hours under occluded contact to intact and abraded skin. Animals were then observed for a period of 72 hours post-treatment. Irritation was scored by the method of Draize (1944). Examinations at 24.5 and 72 hours post-treatment with the undiluted test substance moistened with saline indicated no signs of erythema or edema on the abraded or intact skin of the six rabbits. Based on these findings, UNITAC 70 (rosin, reaction products with formaldehyde) was not considered to be a skin irritant to rabbits, and presents a low skin irritation hazard.