Aluminium orthophosphate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

The study was performed between 19 January 2010 and 25 January 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: EU Guideline Testing of Chemicals B46

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: OECD Draft Test Guideline (version 4)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 15-09-2009 Date of Signature: 26-11-2009

Test material

Test material information

Constituent 1

Reference substance name:

Aluminium orthophosphate

EC Number:

232-056-9

EC Name:

Aluminium orthophosphate

Cas Number:

7784-30-7

Molecular formula:

Al.H3O4P

IUPAC Name:

[phosphato(3-)-kappa~3~O,O',O'']aluminum

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Sponsor’s identification : Aluminium orthophosphate
Description : white powder
Batch number : A88770A
Date received : 28 August 2009
Expiry date : 05 June 2010
Storage conditions : room temperature in the dark

Test animals

Species:

other: reconstituted human epidermis model

Strain:

other: reconstituted human epidermis model

Details on test animals or test system and environmental conditions:

Not applicable

Test system

Type of coverage:

other: Topical

Preparation of test site:

other: Not applicable

Vehicle:

other: No vehicle used

Controls:

no

Amount / concentration applied:

TEST MATERIAL

- The test Material was applied neat.

- 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 & 42 hour post exposure incubation

Observation period:

Not applicable

Number of animals:

Not applicable

Details on study design:

TEST SITE
- Area of exposure:
10 ± 2 mg of the test material was applied to the epidermis surface pre-moistened with 5 µl of sterile distilled water.

- % coverage:
The test material was applied topically to the corresponding tissues ensuring uniform covering.

- Type of wrap if used:
None used

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:

99.6

Vehicle controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

The relative mean viability of the test material treated tissues was 99.9% after a 15-minute exposure.

Any other information on results incl. tables

RESULTS

Direct MTT Reduction

The MTT solution containing the test material did not turn blue/purple which indicated that the test material did not directly reduce MTT.

Test Material, Positive Control Material and Negative Control Material

The individual and mean OD₅₄₀ values, standard deviations and tissue viabilities for the test material, negative control material and positive control material are given in Table 1. The mean viabilities and standard deviations of the test material and positive control, relative to the negative control are also given in Table 1.

The relative mean viability of the test material treated tissues was 99.9% after a 15 minute exposure.

The qualitative evaluation of tissue viability is given in Table 2.

Following the 15-minute exposure the test material treated tissues appeared blue/white which was considered indicative of viable tissue.

Quality Criteria

The relative mean tissue viability for the positive control treated tissues was ≤40% relative to the negative control treated tissues and the standard deviation value of the percentage viability was ≤20%. The positive control acceptance criterion was therefore satisfied.

The mean OD₅₄₀ for the negative control treated tissues was ≥0.6 and the SD value of the percentage viability was ≤20%. The negative control acceptance criterion was therefore satisfied.

Table1 : Mean OD₅₄₀ Values and Percentage Viabilities for the Negative Control Material, Positive Control Material and Test Material

Material	OD540of tissues	Mean OD540of triplicate tissues	±SDof OD540	Relative individual tissue viability (%)	Relative mean viability (%)	± SD of Relative mean viability (%)
Negative Control Material	0.787	0.825	0.054	95.4	100*	6.6
	0.887			107.5
	0.801			97.1
Positive Control Material	0.037	0.033	0.005	4.5	4.0	0.6
	0.034			4.1
	0.027			3.3
Test Material	0.840	0.824	0.022	101.8	99.9	2.7
	0.799			96.8
	0.834			101.1

SD=    Standard deviation

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

Table2 : Qualitative Evaluation of Tissue Viability (MTT uptake visual evaluation)

Material	Tissue 1	Tissue 2	Tissue 3
Negative Control Material	-	-	-
Positive Control Material	++	++	++
Test Material	-	-	-

MTT visual scoring scheme
-          =         blue tissue (viable)
+         =         blue/white tissue (semi-viable)
++       =         tissue is completely white (dead)

Applicant's summary and conclusion

Interpretation of results:

not irritating

Conclusions:

The test material was considered to be Non-Irritant (NI)
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 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).

Executive summary:

Introduction.

The purpose of this test was to evaluate the skin irritation potential of the test material using the EPISKINTM reconstituted human epidermis model after a treatment period of 15 minutes followed by a post-exposure incubation period of 42 hours. The principle of the assay was based on the measurement of cytotoxicity in reconstituted human epidermal cultures following topical exposure to the test material by means of the colourimetric MTT reduction assay. Cell viability is measured by enzymatic reduction of the yellow MTT tetrazolium salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to a blue formazan salt (within the mitochondria of viable cells) in the test material treated tissues relative to the negative controls. The concentration of the inflammatory mediator IL-1α in the culture medium retained following the 42 hour post-exposure incubation period is also determined for test materials which are found to be borderline non-irritant based upon the MTT reduction endpoint. This complimentary end-point will be used to either confirm a non-irritant result or will be used to override the non-irritant result.

Triplicate tissues were treated with the test material for an exposure period of 15 minutes. At the end of the exposure period each tissue was rinsed before incubating for approximately 42 hours. At the end of the post-exposure incubation period each tissue was taken for MTT-loading. The maintenance medium from beneath each tissue was transferred to pre-labelled micro tubes and stored in a freezer for possible inflammatory mediator determination. After MTT loading a total biopsy of each epidermis was made and placed into micro tubes containing acidified isopropanol for extraction of formazan crystals out of the MTT-loaded tissues.

At the end of the formazan extraction period each tube was mixed thoroughly and duplicate 200 μl samples were transferred to the appropriate wells of a pre-labelled 96-well plate. The optical density was measured at 540 nm.

Data are presented in the form of percentage viability (MTT reduction in the test material treated tissues relative to negative control tissues).

Results: The relative mean viability of the test material treated tissues was 99.9% after a 15-minute exposure.

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

Conclusion: The test material was considered to be Non-Irritant (NI).