Rosin, decarboxylated

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020-10-06 to 2020-10-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Decarboxylated Rosin

Cas Number:

8050-18-8

Molecular formula:

Not availabe for UVCB substance

IUPAC Name:

Decarboxylated Rosin

Test material form:

liquid

In vitro test system

Test system:

human skin model

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

0.9 mL of this assay medium at room temperature, was pipetted into the wells of two pre-labeled 6-well plates.

Duration of treatment / exposure:

The tissues were exposed to the test item for a 3-Minute and 60-Minute period.

Duration of post-treatment incubation (if applicable):

The rinsed tissues were incubated at 37 C°, 5% CO2 in air for 3 hours.

Number of replicates:

In duplicate

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Remarks:

3 minutes

Value:

98.1

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation / corrosion parameter:

% tissue viability

Remarks:

60 minutes

Value:

93.4

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

The mean OD570 for the negative control treated tissues was 1.884 for the 3-Minute exposure period and 2.067 for the 60-Minute exposure period. The negative control acceptance criteria were therefore satisfied.
The relative mean tissue viability for the positive control treated tissues was 3.0% relative to the negative control following the 60-Minute exposure period. The positive control acceptance criterion was therefore satisfied.
In the range 20 to 100% viability the Coefficient of Variation between the two tissue replicates of each treatment group did not exceed 30%. The acceptance criterion was therefore satisfied.

Any other information on results incl. tables

Table 1 - Mean OD₅₇₀Values and Viabilities for the Negative Control Item, Positive Control Item and Test Item

Tissue	Exposure Period	Mean OD570of individual tissues	Mean OD570of duplicate tissues	Standard Deviation	Coefficient of Variation (%)	Relative Mean Viability (%)
Negative Control	3 Minutes	1.979	1.884	0.135	7.2	100*
		1.788
	60 Minutes	2.040	2.067	0.038	1.8
		2.094
Positive Control	3 Minutes	0.071	0.065	0.008	NA	3.5
		0.059
	60 Minutes	0.078	0.063	0.021	NA	3.0
		0.048
Test Item	3 Minutes	2.017	1.848	0.239	12.9	98.1
		1.679
	60 Minutes	2.100	1.931	0.240	12.4	93.4
		1.761

*=          The mean viability of the negative control tissues is set at 100%

Applicant's summary and conclusion

Conclusions:

In this study and under the experimental conditions reported:
The test item was considered to be non-corrosive to the skin.
EU CLP Not classified for corrosion.

Executive summary:

The purpose of this test was to evaluate the corrosivity potential of the test item using the EpiDerm™ Human Skin Model after treatment periods of 3 and 60 minutes. Corrosion is directly related to cytotoxicity in the EpiDerm™ tissue. Cytotoxicity is determined by the reduction of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to formazan by viable cells in the test item treated tissues relative to the corresponding negative control. Viable cells are able to reduce MTT to formazan whereas non-viable cells cannot. The results are used to make a prediction of the corrosivity potential of the test item (increased cytotoxicity is indicative of corrosion potential).

Duplicate tissues were treated with the negative control, positive control and test item for exposure periods of 3 and 60 minutes. As the test item had been shown to directly reduce MTT additional non-viable, freeze-killed, tissues were incorporated into the testing for correction purposes. At the end of the exposure period the test item was rinsed from each tissue before each tissue was taken for MTT-loading. After MTT-loading each tissue was placed in 2 mL of isopropanol for MTT extraction. At the end of the formazan extraction period each well was mixed thoroughly and triplicate 200 µL samples were transferred to the appropriate wells of a pre-labeled 96-well plate. The optical density (OD) was measured at 570 nm (OD570). Data are presented in the form of percentage viability (MTT reduction in the test item treated tissues relative to negative control tissues).

The relative mean viabilities for the test item treatment groups were 98.1 and 93.4% for 3 and 60 minute exposures respectively. The mean viability of the negative control tissues is set at 100% and positive control tissues elicited a positive response with percentage viabilities of 3.5 and 3.0% for 3 and 60 minute exposures respectively.The criteria required for acceptance of results in the test were satisfied.

The results obtained showed that no negligible interference due to direct reduction of MTT by the test item occurred in the main test. It was therefore considered unnecessary to use the results of the freeze-killed tissues for quantitative correction of results.

In conclusion, this study and under the experimental conditions reported the test item was considered to be non-corrosive to the skin.