Neodymium trihydroxide

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 August 2016 to 12 August 2016

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

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

28 July 2015

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

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: EpiSkin(TM) SOP, ECVAM Skin Irritation Validation Study: Validation of the EpiSkin(TM) test method 15 min - 42 h for the prediction of acute skin irritation of chemicals

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Neodymium trihydroxide

EC Number:

240-514-4

EC Name:

Neodymium trihydroxide

Cas Number:

16469-17-3

Molecular formula:

H3NdO3

IUPAC Name:

neodymium trihydroxide

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): neodymium trihydroxide
- Physical state: solid
- Appearance: clear blue powder (purple under UV light)

Specific details on test material used for the study:

- correction factor: a correction factor of 1.17 was used in this study

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: not specified (adult)

Source strain:

other: not applicable

Justification for test system used:

The EPISKIN (SM) model has been validated for irritation testing in an international validation study and its use is recommended by the relevant OECD guideline for irritation testing (OECD No. 439). Therefore, it was considered to be suitable for this study.

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EPISKIN (SM) (0.38 cm2), SkinEthic, France
- Tissue batch number(s): 16-EKIN-032
- Expiry date: August 15, 2016
- Date of initiation of testing: August 10, 2016

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 24.4-26.4°C
- Temperature of post-treatment incubation (if applicable): 37.0 ± 1.0°C
- All incubations were carried out in a humid atmosphere (80-100%) containing 5.0 ± 0.5% CO2 in air in the dark at 37.0 ± 1.0°C. Temperature and humidity were continuously monitored once on each working day. Temporary deviations from the temperature, humidity and CO2 percentage may occur due to opening and closing of the incubator door. Any variation to these conditions were evaluated and maintained in the raw data.

REMOVAL OF TEST MATERIAL AND CONTROLS
- Volume and number of washing steps: After 15 min incubation time, the EPISKIN (SM) units were removed and rinsed thoroughly with phosphate buffered saline (PBS) to remove any remaining material from the epidermal surface as much as possible. The rest of the PBS was removed from the epidermal surface with a pipette (without touching the epidermis).
- Observable damage in the tissue due to washing: no

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 0.3 mg/mL
- Incubation time: 3 hours
- Spectrophotometer: yes, plate reader, not further specified
- Wavelength: 570 nm

NUMBER OF REPLICATE TISSUES: 3

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be non-irritant to skin if the relative mean viability of three individual tissues after 15 minutes exposure to the test item and 42 hours post incubation is more than 50% of the mean variability of the negative controls.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 11.7 mg

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): 5% (w/v)

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

3

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean of 3 replicates

Value:

100.6

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: no
- Direct-MTT reduction: no
- Colour interference with MTT: no

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Acceptance criteria met for variability between replicate measurements: yes

Any other information on results incl. tables

Optical density and the calculated non specific colour % of the additional control tissue

Additional control	Optical density			NSC %
		measured	blank corrected
treated with neodymium trihydroxide	1	0.054	0.007	2.1
	2	0.070	0.024
	mean	-	0.015

Optical density and the calculated relative viability % of the samples

Substance		Optical density		Viability
		measured	blank corrected	(% RV)
negative control: phosphate buffered saline	1	0.766	0.720	96.2
	2	0.745	0.699	93.4
	3	0.872	0.825	110.3
	mean	-	0.748	100.0
positive control: 5% w/v SDS solution	1	0.091	0.045	6.0
	2	0.149	0.103	13.7
	3	0.098	0.051	6.8
	mean	-	0.066	8.8
test item: neodymium trihydroxide	1	0.767	0.720	96.3
	2	0.839	0.792	105.9
	3	0.791	0.745	99.6
	mean	-	0.752	100.6

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study (in vitro EPISKIN model test according to OECD guideline 439), neodymium trihydroxide was determined to be non-irritant to skin. Based on these results, the test item is considered not classified according to the CLP Regulation.