2-methoxy-4-propylphenol

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02-03 September 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

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

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

UK GLP Compliance Programme (inspected on June 17, 2015 / signed on September 24, 2015)

Test material

Test material information

Constituent 1

Reference substance name:

2-methoxy-4-propylphenol

EC Number:

220-499-0

EC Name:

2-methoxy-4-propylphenol

Cas Number:

2785-87-7

Molecular formula:

C10H14O2

IUPAC Name:

2-methoxy-4-propylphenol

Test material form:

liquid

Details on test material:

- Physical state: Colourless, oily liquid
- Storage condition of test material: Room temperature

Specific details on test material used for the study:

Storage condition of test material: Room temperature in the dark

In vitro test system

Test system:

isolated skin discs

Source species:

rat

Source strain:

Wistar

Details on animal used as source of test system:

TEST ANIMALS
- Strain: Wistar (RccHan™:WIST)
- Source: Envigo RMS (UK) Limited, Oxon, UK.
- Sex: female
- Age at the start of pelt preparation: 21-23 days
- Housing: Animal was housed in a suspended solid-floor polypropylene cage furnished with woodflakes.
- Diet: Food (2014C Teklad Global Rodent diet supplied by Envigo RMS (UK) Limited, Oxon, UK), ad libitum
- Water: Mains drinking water, ad libitum
- Acclimatization period: 2 days

ENVIRONMENTAL CONDITIONS
- Temperature: 19-25 °C
- Humidity: 30-70 %
- Air changes: At least fifteen changes per hour
- Photoperiod: 12 h dark / 12 h light

Justification for test system used:

Following the REACH bottom-up strategy, the Transcutaneous Electrical Resistance Assay was used to assess skin corrosion as recommended in the OECD test guideline No. 439. This method was chosen because the registered substance was considered incompatible with the EpiDerm™ skin corrosivity test due to non-specific reduction of MTT by the test substance.

Vehicle:

unchanged (no vehicle)

Details on test system:

SKIN DISC PREPARATION
- Procedure used: Following an acclimatization period of 2 days the animal was shaved to remove hair from the dorsal surface and skin area was washed using an antibiotic wash. After 3 days a second antibiotic wash was performed. Two days later the animal was killed using ascending concentrations of carbon dioxide followed by cervical dislocation. The dorsal skin was removed from the rat as a single pelt. Excess fat was removed and the pelt mounted, epidermal side uppermost, onto a polytetrafluoroethylene (PTFE) tube. The tissue was secured in place using a rubber “O” ring. Excess tissue was trimmed away and the “O” ring/PTFE interface sealed with soft paraffin wax. The tube was supported by a clamp inside a labelled 30 mL glass receptacle containing 10 mL electrolyte solution (154 mM MgSO4).
- Quality control for skin discs: Electrical resistance obtained with two of the isolated skin discs was greater than 10 kΩ in order for the remainder of the pelt to be used in the assay

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 20 to 23°C

REMOVAL OF TEST MATERIAL AND CONTROLS
- Number of washing steps: not reported. At the end of the exposure period, the test item was removed by washing the skin disc with a jet of warm tap water until no further test item could be removed
- Observable damage in the tissue due to washing: no obvious damage reported
- Modifications to validated SOP: none reported

DYE BINDING METHOD
- Dye used in the dye-binding assay: None (Dye penetration is assessed only if the mean TER value of the test item is less than or equal to 5 kΩ)

NUMBER OF INDEPENDENT TESTING RUNS / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be corrosive to skin if the mean TER value is less than or equal to 5 kΩ and the skin disk is obviously damaged, or if the mean TER value is less than or equal to 5 kΩ, and the skin disc is showing no obvious damage, but the mean disc dye content is greater than or equal to the mean disc dye content of the 10M HCl positive control obtained concurrently.
- The test substance is considered to be non-corrosive to skin if the mean TER value obtained for the test substance is greater than 5 kΩ, or if the mean TER value is less than or equal to 5 kΩ, and the skin disc is showing no obvious damage, and the mean disc dye content is well below the mean disc dye content of the 10M HCl positive control obtained concurrently.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 150 μL of test item was applied to the inner epidermal surface of skin discs using an automatic pipettor
- Concentration (if solution): undiluted

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 150 μL
- Concentration (if solution): Sterile distilled water

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 150 μL
- Concentration (if solution): 10M hydrochloric acid (approximately 36%)

Duration of treatment / exposure:

Test item was applied to the epidermal surface of three skin discs for a contact period of 24 hours.

Number of replicates:

Total: 9 skin discs - 3 skin discs/group for test item, negative and positive controls

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

transcutaneous electrical resistance (in kΩ)

Run / experiment:

24 hours exposure period

Value:

9.3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: No indication of corrosion

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: no

DEMONSTRATION OF TECHNICAL PROFICIENCY: yes

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes (20.6 kΩ)
- Acceptance criteria met for positive control: yes (860.3 Ω)
- Acceptance criteria met for variability between replicate measurements: yes

Any other information on results incl. tables

Table 7.3.1/1: Individual and mean transcutaneous electrical resistance measurements

 

Treatment	Tissue Number	TER (kΩ)	Mean TER ± SD(kΩ)
Test Item	1	10.5	9.3 ± 2.0
	2	7.0
	3	10.4
Positive Control	4	0.909	0. 8603 ± 0.00485
	5	0.812
	6	0.860
Negative Control	7	15.3	20.6 ± 8.0
	8	29.8
	9	16.6

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the test conditions, with a mean TER of 9.3 kΩ (> 5 kΩ) the test item was considered to be non-corrosive to skin according to the Regulation (EC) No. 1272/2008 (CLP) and to the GHS.

Executive summary:

An in vitro skin irritation study was performed according to the OECD Guideline 430 and in compliance with GLP, using the Transcutaneous Electrical Resistance (TER) Assay. The test item (150 μL) was applied to the epidermal surface of three skin discs for a contact period of 24 hours. At the end of the exposure period, the test item was removed by washing the skin disc with a jet of warm tap water until no further test item could be removed. The positive control was 10M hydrochloric acid (approximately 36%) and the negative control was sterile distilled water. The contact period for the positive and negative controls was 24 hours. The TER was measured using a Wheatstone Bridge with a low voltage alternating current and mean TER for the skin discs was calculated.

 

The mean TER recorded for the test item was 9.3 kΩ. The mean TER recorded for the positive and negative control discs were as follows: Positive control disc, 10M Hydrochloric acid (approximately 36%): 860.3 Ω and Negative control disc, Sterile distilled water: 20.6 kΩ. The mean TER values for the positive and negative control discs were within the acceptable range for the method, and the variability between skin disc replicates was considered to be acceptable, therefore the test results were considered to be valid.

 

Under the test conditions, with a mean TER of 9.3 kΩ (> 5 kΩ)  the test item was considered to be non-corrosive to skin according to the Regulation (EC) No. 1272/2008 (CLP) and to the GHS.