Suberic acid

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-03-02 - 2018-03-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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 430 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test Method (TER))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Suberic acid

EC Number:

208-010-9

EC Name:

Suberic acid

Cas Number:

505-48-6

Molecular formula:

C8H14O4

IUPAC Name:

octanedioic acid

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Molecular Formula:
C8H14O4
Molecular Mass:
174.20
Characteristics (Physical Appearance):
White Crystalline powder
CAS No.:
505-48-6
Batch Number:
308
Purity:
100%

In vitro test system

Test system:

isolated skin discs

Source species:

rat

Cell type:

non-transformed keratinocytes

Cell source:

foreskin from multiple donors

Source strain:

Wistar

Details on animal used as source of test system:

Species:
Rat (Rattus norvegicus)
Strain:
Wistar
Justification of selection:
Rat is the rodent species and Wistar is the strain recommended by the test guideline.
Source:
Bred and reared at INTOX PVT. LTD.
Age at start of study:
22 days
No. of animals and sex:
10 males
Environmental conditions:
The experimental animal room was supplied with fresh and filtered air, with 10 to 15 air changes per hour. The room was air conditioned with temperature between 19 to 25 oC, relative humidity 30 to 70% and illumination cycle set to 12 hours light and 12 hours dark.

Vehicle:

water

Details on test system:

PREPARATION OF ANIMALS:
Veterinary examination : Prior to assignment to the study, the animals were subjected to a veterinary examination to ensure that the selected rats were in a good state of health.
Removal of Hairs : The dorsal and flank hair from young, 22 day old male and female rats were closely clipped with an electric clipper. Care was taken to avoid skin injury or abrasion.
Selection of animals : Skin of each rat was then examined to ensure that animals with healthy intact skin were used for the test.
Washing with antibiotic solution: The animals were washed by careful wiping, of clipped area with cotton soaked in antibiotic solution after hair clipping. Animals were washed with antibiotic solution again on the day after the first wash and were used on 3rd day after second wash.
ANTIBIOTIC SOLUTION:
The antibiotic solution was prepared by adding streptomycin, penicillin, chloramphenicol and amphotericin B to luke-warm analytical grade water such that, the resulting solution contained following concentrations.
Streptomycin 8 mg/ml
Penicillin 800 μg/ml
Chloramphenicol 10 μg/ml
Amphotericin B 10 μg/ml
PREPARATION OF THE SKIN DISCS:
Animals were humanely sacrificed by CO2 asphyxiation, when they was 28 days old. The dorso-lateral skin of each animal was then removed and stripped of excess subcutaneous fat by peeling it away from the skin. Skin discs, with a diameter of approximately 20 mm each, were prepared using scissors. As many as 4-5 skin discs were obtained from a single rat skin.
FITTING OF SKIN DISC TO PTFE TUBES
Each skin disc was placed over one of the ends of a PTFE (polytetrafluoroethylene) tube, ensuring that the epidermal surface is in contact with the tube. A rubber "O" ring was press-fitted over the end of the tube to hold the skin in place and excess tissue was trimmed away.
The tube was supported by a rubber cork inside a receptor chamber containing MgSO4 solution (154 mM). The skin disc was fully submerged in the MgSO4 solution.
Before testing begins, the electrical resistance of skin discs was measured as a quality control procedure for each animal skin.

Control samples:

yes, concurrent vehicle

yes, concurrent positive control

Amount/concentration applied:

150 mg + 150 L analytical grade water

Duration of treatment / exposure:

24 hours

Number of replicates:

3

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

transcutaneous electrical resistance (in kΩ)

Run / experiment:

test item

Value:

14.65

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation / corrosion parameter:

transcutaneous electrical resistance (in kΩ)

Run / experiment:

positive control

Value:

0.78

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 3

Irritation / corrosion parameter:

transcutaneous electrical resistance (in kΩ)

Run / experiment:

negative control

Value:

15.83

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The mean TER value obtained for test item SUBERIC ACID was 14.65 K (which was greater than 5 k) and the skin discs showed no obvious damage (e.g. perforation). The mean disc dye content was 36.16 μg/disc, which was lesser than the mean disc dye content of the 10M HCl positive control obtained concurrently.
According to the criteria of acceptance, under the experimental conditions of the study 'In-Vitro Skin Corrosion Study by Transcutaneous Electrical Resistance Test Method (TER) of SUBERIC ACID it is concluded that the test item SUBERIC ACID is considered as non-corrosive to rat skin as per the United Nations(UN) Globally Harmonised System (GHS) for classification of chemicals.

Executive summary:

SUBERIC ACID, was evaluated for its corrosive potential by its ability to produce a loss of normal stratum corneum integrity and barrier function, which was measured as a reduction in the TER below the threshold level (cut-off value) of 5 k Ω for rat skin, and from any increase in the ionic permeability for sulforhodamine B dye.

The skin discs were taken from humanely sacrificed rats aged 28 days and were applied with 150 μL of test item, in triplicate. Concurrent triplicate sets of skin discs were applied either with analytical grade water (150 μl) as negative control or with 10M hydrochloric acid (150 μl) as positive control.

The test and control items were applied for up to 24 hours at 22 °C to the epidermal surfaces of skin discs in a two compartment test system in which the skin disc functioned as the separation between the compartments. The test / control items were then removed by washing with a jet of tap water until no further material could be removed. The skin impedance was measured as TER by using Aplab Autocompute LCR-Q meter 4910. The electrodes of LCR-Q meter were placed on either side of the skin disc to measure the resistance of skin disc at a frequency of 100 Hz and using series values. Following TER measurement, the skin was carefully examined for obvious damage. After visual examination, 10% (w/v) sulforhodamine B was applied to the epidermal surface of each skin disc for 2 hours, which was followed by the measurement of dye content in each skin disc.

The mean resistance of the skin in the negative control group was found to be 15.83 K Ω which was within the acceptable range of 10 to 25 k Ω and the mean dye content of skin disc was 40.98 μg/disc which was closer to the acceptable range of 15 to 35 μg/disc.

The mean resistance of the skin in the positive control group was found to be 0.78 K Ω which was within the acceptable range of 0.5 to 1.0 k Ω while the mean dye content of skin disc was 63.74 μg/disc, which was within the acceptable range of 40 to 100 μg/disc, thereby validating the experimental procedure.

The mean TER value obtained for SUBERIC ACID was 14.65 K Ω which was greater than 5 k Ω, the skin discs showed no obvious damage (e.g. perforation) and mean disc dye content was found to be 36.16 μg/disc which was lesser than that observed in skin discs treated with the positive control item.

Under the given experimental conditions of this study, it is concluded that the test item SUBERIC ACID is considered non-corrosive to skin of the rat.