Terpene

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

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

Test material

Test material information

Constituent 1

Reference substance name:

Product obtained by rectification during the manufacturing process of Dihydromyrcenol

Molecular formula:

C10H18

IUPAC Name:

Product obtained by rectification during the manufacturing process of Dihydromyrcenol

In vitro test system

Test system:

artificial membrane barrier model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: episkin

Source strain:

not specified

Vehicle:

physiological saline

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

50 µL

Duration of treatment / exposure:

Exposure times of 3, 60±5 and 240±5 minutes

Number of replicates:

2

Test system

Type of coverage:

open

Preparation of test site:

not specified

Vehicle:

physiological saline

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

50 µL

Duration of treatment / exposure:

Exposure times of 3, 60±5 and 240±5 minutes

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

240 minutes

Value:

ca. 53

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

TwoMain Assays were performed.

In the firstMain Assay, the mean Optical Density of Blank Controls was 0.037, lower than the maximum acceptable value (0.1). All negative control mean OD values gave the expected baseline value and variability, in agreement with guideline indications. According to the method, each negative control mean value is considered the baseline value for the concurrent treatment series, thus they represent 100% of cell viability. Positive control results indicated an appropriate cell death with an acceptable relative cell viability (1% of the negative control value).

Based on the stated criteria, the experiment was accepted as valid.

The test item did not induce cell death in any replicate, after 3 or 60 minutes of treatment time. Marked reduction of mean percent viability was noted at 240 minute treatment time.

Each mean cell viability, after the concurrent blank subtraction, was as follows:

Treatment time (minutes)              Mean cell viability (%)

3                                                 113

60                                                140

240                                               34

Intra-replicate variability was acceptable with a difference of viability between the two replicates lower than 30%, for all treatment times.

Results obtained in this experiment using the longest treatment time (240 minutes) should be considered borderline, as viability values of the replicated tissues were one above and one below the threshold value. Moreover, test item features and results obtained for eyes corrosion are predictive of no corrosive potential for the skin. Based on these considerations, a Main Assay II was performed. In this second experiment, a slight reduction of mean percent viability was noted at all treatment times.

Each mean cell viability, after the concurrent blank subtraction, was as follows:

Treatment time (minutes) Mean cell viability (%)

3 61

60 80

240 53

Also in this experiment all the acceptability criteria were met with the exception that after 60 minutes of treatment intra-replicate variability slightly exceeded the maximum acceptable value (Δ%= 35.8). However, the results obtained with the replicate tissues were both predictive of no corrosive potential and thus were considered acceptable.

For each treatment time, the average of viability values obtained in the two experiments was calculated and results obtained were as follows:

Treatment time (minutes) Mean cell viability (%) - two experiments

3 87

60 110

240 44

Based on the results obtained, the test item TERPENIC BASE is identified as non-corrosive to the skin.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The potential of the test item TERPENIC BASE to be corrosive to the skin was investigated through an in vitro skin corrosion study, using a commercial reconstructed human epidermis (RhE) model named EPISKIN™.
The blank, negative and positive controls gave acceptable results at all treatment times, thus the study was accepted as valid.
After 240 minutes of treatment, a reduction of mean percent viability to 34% of the concurrent negative control value was noted.

Based on this result, the test item TERPENIC BASE is identified as non-corrosive to the skin.