Tripotassium orthophosphate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 June 2012 - 18 June 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 19-21 July 2011, signed 31 August 2011

Test material

Test material information

Constituent 1

Reference substance name:

Tripotassium orthophosphate

EC Number:

231-907-1

EC Name:

Tripotassium orthophosphate

Cas Number:

7778-53-2

Molecular formula:

H3O4P.3K

IUPAC Name:

tripotassium orthophosphate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Sponsor's identification : Tripotassium orthophosphate
Description : white powder
Batch number : 1136181
Purity : 96.9%
Date received : 14 March 2012
Expiry date : 01 December 2013
Storage conditions : room temperature in the dark

Test animals

Species:

other: reconstituted human epidermis model

Strain:

other: reconstituted human epidermis model

Test system

Type of coverage:

other: Topical

Preparation of test site:

other: not applicable

Vehicle:

unchanged (no vehicle)

Controls:

other: Control animals are not applicable, however controls were used in the study.

Amount / concentration applied:

The test item was used as supplied.

- Amount(s) applied (volume or weight with unit):
10 ± 2 mg of the test material was applied to the epidermis surface pre-moistened with 5 µl of sterile distilled water.

- Concentration (if solution):
The test material was used as supplied.

VEHICLE
No vehicle used

Duration of treatment / exposure:

15 minutes and 42 hours post-exposure incubation.

Observation period:

Not applicable

Number of animals:

Not applicable

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done):
At the end of the exposure period, each tissue was removed from the well using forceps and rinsed using a wash bottle containing PBS with Ca++ and Mg++. Rinsing was achieved by filling and emptying each tissue insert for approximately 40 seconds using a constant soft stream of PBS to gently remove any residual test material.

- Time after start of exposure:
15 Minutes post exposure

SCORING SYSTEM:
Quantitative MTT Assessment (percentage tissue viability)
For the test material the relative mean tissue viabilities obtained after the 15 minute treatment followed by the 42 hour post-exposure incubation period were compared to the mean of the negative control treated tissues (n=3). The relative mean viabilities were calculated in the following way:

mean OD540 of test material / mean OD540 of negative control x 100 = Relative mean tissue viability (percentage of negative control)

Classification of irritation potential is based upon relative tissue viability following the 15 minute exposure period followed by the 42 hour post-exposure incubation period according to the following:

Mean tissue viability is ≤50% : Irritant (I) R38

Mean tissue viability is >50% : Non-Irritant (NI)

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean value - all three tissues

Value:

81.6

Remarks on result:

other:

Remarks:

Basis: mean viability of cells (%). Time point: day 6. Max. score: 100.0. Reversibility: other: not applicable. Remarks: %. (migrated information)

Any other information on results incl. tables

Test Item, Positive Control Item and Negative Control Item

The mean OD₅₄₀values, standard deviations and tissue viabilities for the test item, negative control item and positive control item are given in Table 1. The mean viabilities and standard deviations of the test item and positive control, relative to the negative control are also given in Table 1.

The relative mean viability of the test item treated tissues was 81.6% after a 15-Minute exposure period.

 

Quality Criteria

The relative mean tissue viability for the positive control treated tissues was 8.6% relative to the negative control treated tissues and the standard deviation value of the percentage viability was 1.0%. The positive control acceptance criterion was therefore satisfied.

The mean OD540 for the negative control treated tissues was 0.659 and the standard deviation value of the percentage viability was 6.2%. The negative control acceptance criterion was therefore satisfied.

The standard deviation calculated from individual percentage tissue viabilities of the three identically treated tissues was 5.2%. The test item acceptance criterion was therefore satisfied.

 

Table 1. Mean OD₅₄₀Values and Percentage Viabilities for the Negative Control Item, Positive Control Item and Test Item

 

Item	OD540of tissues	Mean OD540of triplicate tissues	± SD of OD540	Relative individual tissue viability (%)	Relative mean viability (%)	± SD of relative mean viability (%)
Negative control item	0.666	0.659	0.041	101.1	100*	6.2
	0.696			105.6
	0.615			93.3
Positive control item	0.059	0.056	0.006	9.0	8.6	1.0
	0.061			9.3
	0.049			7.4
Test item	0.560	0.538	0.034	85.0	81.6	5.2
	0.499			75.7
	0.555			84.2

 

SD = Standard deviation

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

Control group shared with Harlan Laboratories Ltd Project numbers 41200853, 41200861,

41200866, 41200871, 41200880, 41200884 and 41201543

The relative mean viability of the test item treated tissues was 81.6% after the 15-minute exposure period.

Quality criteria: The quality criteria required for acceptance of results in the test were satisfied.

Direct MTT Reduction

An assessment found the test item was able to directly reduce MTT. Therefore, an additional procedure using water-killed tissues was performed during the determination of skin irritation potential. However, the results obtained showed a negligible degree ofinterference due to direct reduction of MTT occurred. It was therefore considered unnecessary to use the results of the water-killed tissues for quantitative correction of results or for reporting purposes.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of the study tripotassium orthophosphate is considered to be a non-irritant.
This study is conducted according to an appropriate validated in vitro guideline and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement (Regulation (EC) No. 1907/2006; REACH) as a key study for this endpoint. In addition, the data is considered to be adequate and reliable for classification and labelling in accordance with Regulation (EC) No. 1272/2008 (EU CLP). Tripotassium orthophosphate is not considered to be classified in accordance with Regulation (EC) No. 1272/2008 (EU CLP).