Reaction mass of orthophosphoric acid and potassium dihexadecyl phosphate and dipotassium hexadecyl phosphate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From May 18, 2017 to June 23, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Deviations:

yes

Remarks:

Deviation was not considered to have affected the integrity or interpretation of the results

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of mono- and di- hexadecyl phosphate esters, potassium salts and phosphoric acid

Molecular formula:

C16H34O4P1K1 (representative: mono- C16 PSE, K+)

IUPAC Name:

Reaction mass of mono- and di- hexadecyl phosphate esters, potassium salts and phosphoric acid

Test material form:

solid: particulate/powder

In vitro test system

Test system:

human skin model

Remarks:

MatTek EpiDermTM tissue model EPI-200

Cell type:

other: Normal human-derived epidermal keratinocytes which have been cultured to form a multi-layered highly differentiated model of the human epidermis.

Justification for test system used:

Initially the predictive capacity of the modified EpiDerm™ Skin Irritation Test (SIT) test method, using MatTek EpiDermTM tissue model EPI-200, underwent full prospective validation from 2003-2007. The test method components of this method were used to define the essential test methods components of the original and updated ECVAM Performance Standards (PS). A modification of the original EpiDerm™ SIT was validated using the original ECVAM PS in 2008. In 2008, ESAC concluded that the Modified EpiDerm™ SIT has sufficient accuracy and reliability for prediction of R38 skin irritating and no-label (non-skin irritating) test substances.

Vehicle:

unchanged (no vehicle)

Details on test system:

Test system:
The reconstructed human epidermal model EpiDermTM (EPI-200-MatTek Corporation) consists of normal human-derived epidermal keratinocytes which have been cultured to form a multi-layered highly differentiated model of the human epidermis. It consists of organised basal, spinous and granular layers and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo.

Characterisation of the test system:
MatTek’s EpiDermTM model has been extensively characterised for multiple parameters including morphology, tissue viability, skin barrier function and sterility. QC results for the specific lot of models received (Lot# 25819) were checked in-house for MatTek acceptance ranges with the following outcome:
- Morphology - PASS
- Tissue viability - PASS
- Skin barrier function (ET50 value for 1 % Triton X-100) where ET50 is the time taken for 1 % Triton X-100 to reduce the viability of the skin model to 50 % relative to the negative control) - PASS
- Sterility testing showed no contamination during long term antibiotic and antimycotic free culture - PASS

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

25 mg after pre-wetting with 25 uL of DPBS

Duration of treatment / exposure:

60 ± 1 minutes of treatment

Duration of post-treatment incubation (if applicable):

42 ± 4 h

Number of replicates:

3 replicates for the test substance, positive and negative control

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Test substance

Value:

ca. 93.5

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Positive control

Value:

ca. 3.1

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of irritation

Results 3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Negative control

Value:

ca. 100

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

- Prior to the study, the required compatibility checks (as per SOP L0029) confirmed that the test substance did not interfere with MTT and no water colouration was observed.

Any other information on results incl. tables

Results

Table 1: Viability measurements after 60 ±1 min of application and 42 ± 4 h post-incubation of test and reference substances and controls

Condition	Tissue #	Raw data		Blank corrected data		Mean OD	% of Viability
		Aliquot 1	Aliquot 2	Aliquot 1	Aliquot 2
NC	Tissue 1	1.967	2.084	1.800	1.917	1.858	100.6
	Tissue 2	2.095	2.182	1.928	2.015	1.971	106.8
	Tissue 3	1.856	1.897	1.689	1.730	1.709	92.6
PC	Tissue 1	0.225	0.2	0.058	0.033	0.045	2.4
	Tissue 2	0.237	0.217	0.070	0.050	0.060	3.2
	Tissue 3	0.24	0.229	0.073	0.062	0.067	3.6
TA2	Tissue 1	2.005	2.027	1.838	1.860	1.849	100.1
	Tissue 2	2.008	1.821	1.841	1.654	1.747	94.6
	Tissue 3	1.698	1.799	1.531	1.632	1.581	85.6

NC: negative control (DPBS), PC: Positive control (SDS 5%), TA2: Test substance.

Note: Rounded figures used.

Table 2: Mean and SD of cell viability measurements and of viability percentages after a 60 ±1 min application and 42 ± 4 h post-incubation

Name	Code	Mean of OD	SD of OD	Mean of viability (%)	SD of viability (%)	CV %	Classification
DPBS	NC	1.846	0.131	100.0	7.12	7.12	Non-Irritant
SDS 5%	PC	0.057	0.011	3.1	0.61	19.51	Irritant
Test substance	TA2	1.726	0.135	93.5	7.31	7.83	Non-Irritant

Prediction model of irritancy: test substances that reduce the viability to 50% or below are irritant (I), test substances with a percentage viability above 50% are considered to be non-irritant (NI).

Note: Rounded figures used.

Evaluation of the results

Results were checked against the following acceptance criteria:

	Description	Actual values	PASS/FAIL
Acceptance criterion 1	The mean OD570 of the negative control tissues is≥ 0.8 and ≤ 2.8	1.846	PASS
Acceptance criterion 2	The mean of the positive control relative percentage viability must be ≤ 20% of the mean of the negative controls.	3.1%	PASS
Acceptance criterion 3	The standard deviation of OD values for triplicate skin models in each experimental condition must be < 18%	NC: 7.12% PC: 0.61% TA2: 7.31%	PASS
Acceptance criterion 4	The mean OD of the 6 wells containing extraction solvent alone (blanks) should be ≤ 0.1.	0.1673	FAIL*

 

*All acceptance criteria were met with the exception of criterion 4:

 

Optical Density (OD) values obtained with blanks were higher than 0.1 (0.1673) causing a deviation from Acceptance Criteria 4. However, the spectrophotometer was fully validated and had passed all required tests. The OD values for blanks observed in this study are consistent with historical data using this spectrophotometer in the XCellR8 laboratory and meet our current internal acceptance criteria of blank OD values < 0.194 (mean XCellR8 historical data, based on blanks obtained during the last 66 studies), therefore this is not considered to be an issue in the interpretation of this study data.

 

This SOP and guideline deviation was not considered to have affected the integrity or interpretation of the results as no equivocal results were obtained.

 

Interpretation of Results following Prediction Model

- A test substance is considered to be an irritant (I) to skin in accordance with UN GHS Category 2 or EU R38 if the skin model viability after exposure and post-treatment incubation is ≤50%.

- A test substance may be considered as a non-irritant (NI) if the skin model viability after exposure and post-treatment incubation is >50%.

The percentage of viability obtained with the test substance was 93.5%, therefore it is considered as non-Irritant to the skin.

Applicant's summary and conclusion

Interpretation of results:

other: CLP

Remarks:

non-irritant based on CLP criteria

Conclusions:

Under the study conditions, the test substance was determined to be non-irritant to skin.

Executive summary:

An in vitro study was conducted to determine the skin irritation potential of the test substance, 'mono- and di- C16 PSE, K+ and H3PO4' (purity: 100%), using Reconstructed Human Epidermis (RHE) method, according to OECD Guideline 439, in compliance with GLP. Three tissues of the human skin model EpiDermTM were treated with the test substance, positive or negative controls for 60 minutes (25 minutes at room temperature and 35 minutes at 37°C, 5 % CO2, 95 % RH) and 42 h post incubation period. Test was performed with 3 replicates for each type of treatment. Tissues were first pre-wetted with 25 μL DPBS (Sterile Dulbecco’s Phosphate Buffered Saline), subsequently 25 mg (nominal) of the neat test substance was applied. 30 μL of DPBS was used as negative control and 5% of sodium dodecyl sulphate (SDS) as positive control. Viability of the tissues was assessed in MTT test and compared to the negative control. The percentage of viability obtained with the test substance was 89.1%, which is well above the irritant limit of 50%. The study met all the validity criteria. Under the study conditions, the test substance was determined to be non-irritating to skin (XCellR8, 2017).