reaction mass of neodymium carbonate and praseodymium carbonate

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-APR-2013 to 03-JUL-2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted in compliance with GLP and according to the OECD guideline 439.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

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)

Version / remarks:

: In vitro skin irritation on EpiskinTM reconstituted human epidermis

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)

Test material

Test material information

Constituent 1

Reference substance name:

reaction mass of neodymium carbonate and praseodymium carbonate

Molecular formula:

(Nd,Pr)2 (CO3)3

IUPAC Name:

reaction mass of neodymium carbonate and praseodymium carbonate

Constituent 2

Reference substance name:

937-221-5

IUPAC Name:

937-221-5

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Test animals

Species:

human

Strain:

other: reconstructed epidermis tissues

Details on test animals or test system and environmental conditions:

IN VITRO MODEL
- Source: SkinEthic Laboratories, Lyon, France
- Description: The Episkin(TM) model consists of an airlifted, living, multilayered epidermal tissue construction (surface 0.38 cm²), reconstituted from normal human epidermal keratinocytes for 13 days and produced in polycarbonate inserts in a serum-free and chemically defined medium. The model features a normal ultra structure and is functionally equivalent to human in vivo epidermis. At receipt, the living Episkin(TM) tissues were kept at room temperature in their packaging until required. Moreover, the pH (colour of the agar medium) and temperature indicators were checked to ensure the good quality of the tissues before use.

Test system

Type of coverage:

other: applied topically

Preparation of test site:

other: not applicable

Vehicle:

unchanged (no vehicle)

Controls:

other: negative control: Dulbecco's Phosphate-Buffered Saline (D-PBS) / positive control: Sodium Dodecyl Sulphate (SDS) at 5% in aqueous solution

Amount / concentration applied:

10 ± 2 mg of the test material applied

Duration of treatment / exposure:

15 ± 1 minutes

Observation period:

At the end of the 15-min treatment period, each tissue was rinsed (to remove the test substance) and the skin irritation potential of the test material was assessed after a 42-h recovery period.

Number of animals:

other: triplicate tissues

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

other: other: relative viability of tissues

Value:

107

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 15 min. Reversibility: other: not applicable. Remarks: ± 12% (SD). (migrated information)

In vivo

Irritant / corrosive response data:

The tissue examination showed that all treated samples appeared blue which was considered indicative for viable tissues.

Other effects:

- PRELIMINARY TEST
The MTT solution containing the test material did not turn blue/purple when compared with the negative control. The test material was therefore considered not to have direct MTT reducing properties. Furthermore, since the water solution containing the test material did not change colour, the test material was considered not to have a colouring potential.

Any other information on results incl. tables

- MAIN TEST:

 

Table 1: cOD values and tissue viabilities for the test material, negative and positive controls

 

Group	Tissue No.	OD measurements		Mean ODblank	cOD		cOD		Viability (%)
		1^st	2^nd		1^st	2^nd	mean	SD	mean	SD
Negative control	1	0.972	0.969	0.038	0.935	0.932	0.968	0.040	100	4
	2	1.042	1.056		1.005	1.019
	3	1.000	0.996		0.963	0.959
Positive control	1	0.161	0.161	0.038	0.124	0.124	0.107	0.015	11	2
	2	0.141	0.142		0.104	0.105
	3	0.133	0.128		0.096	0.091
Test material	1	0.959	0.948	0.037	0.922	0.911	1.040	0.113	107	12
	2	1.181	1.167		1.144	1.130
	3	1.113	1.097		1.076	1.060

OD = optical density

cOD = blank corrected optical density

SD = standard deviation

 

 

Table 2: Qualitative assessment of tissue viability: visual examination of MTT staining.

 

Treatment	Tissue 1	Tissue 2	Tissue 3
Negative control	B	B	B
Positive control	B/W	B/W	B/W
Test material	B	B	B

B = blue discolouration of the tissue (viable)

B/W = white discouloration with a faint blue discolouration in the center of tissues (semi-viable)

Applicant's summary and conclusion

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Since the relative mean viability of tissues treated with the test material was of 107% after a 15-min exposure, the test material was considered to be non-irritant.

Executive summary:

The objective of this GLP-compliant study was to evaluate the skin irritation potential of the test item, reaction mass of neodymium carbonate and praseodymium carbonate, using the Episkin^TM reconstructed human epidermis model, according to the OECD guideline 439.

 

The test item was topically applied in its original form (i.e. solid) with a quantity of 10 ± 2 mg on triplicate tissues. The test item and both the negative (D-PBS) and positive (SDS at 5% in aqueous solution) controls were incubated at room temperature for 15 ± 1 min. At the end of the treatment period, each tissue was rinsed with D-PBS and incubated for 42 ± 1 h at 37°C, 5% CO₂ in a humidified incubator. The cell viability was then assessed by means of the colourimetric MTT reduction assay. Relative viability values were calculated for each tissue and expressed as a percentage of the mean viability of the negative control tissues which was set at 100% (reference viability).

 

In the preliminary tests, the test item was found not to have direct MTT reducing properties or colouring potential. All acceptance criteria for the negative and positive controls were fulfilled. The study was therefore considered to be valid.

Following a 15-min exposure and a 42-h recovery period, the relative mean viability of the tissues treated with the test item was 107% with a standard deviation of 12%.

 

As the mean viability was > 50% after the MTT reduction, the irritancy potential of the test item, reaction mass of neodymium carbonate and praseodymium carbonate, was considered to be non-irritant to skin. Therefore, the test material should not be classified according to Directive 67/548/EEC, Regulation (EC) No. 1272/2008 and UN GHS.