Dysprosium trinitrate

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 2016-09-21 to 2017-08-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Reference

Endpoint:

acidity / alkalinity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 122 (Determination of pH, Acidity and Alkalinity)

Principles of method if other than guideline:

Electrochemic determination of pH: the pH-value of a 10% solution (or slurry) was determined electrochemically at 20°C with a calibrated pH meter (MA 235 Mettler Toledo). This value was recorded.

Determination of the acidic reserve: via titration.

GLP compliance:

no

Remarks:

Company data performed according to an internal method that meets generally accepted scientific principles

Specific details on test material used for the study:

no details available

Reagent:

NaOH solution

Details on titrant used:

Determination of the alkaline or acid reserve via titration:
- For the determination of the alkaline reserve: the titration volume (in mL) of a 0.5 mol/L H2SO4 solution, which is required to achieve a pH of 10 of a 10% solution (or slurry) at 20°C, was recorded.
- For the determination of the acid reserve: the titration volume (in mL) of a 1 mol/L NaOH solution, which is required to achieve a pH of 4 of a 10% solution (or slurry) at 20°C, was recorded.

Key result

pH value:

0.46

Temp.:

20 °C

Concentration:

10 vol%

Key result

Acidity or alkalinity:

acidity

Value:

10.03

Remarks on result:

other: Acid reserve

	pH	Acidic Reserve	Corrosive calculation	Corrosive?
Dysprosium nitrate	0.46	10.03	-0.37	No

Conclusions:

The pH value of a 10% solution of dysprosium trinitrate was determined to be 0.46 and the acid reserve was 10.03. Based on these data, the outcome of the calculation for corrosivity was -0.37 (> -0.5). Therefore the substance was considered not to be corrosive.

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)

Version / remarks:

6 July 2012

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

Version / remarks:

February 2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Dysprosium trinitrate

EC Number:

233-410-5

EC Name:

Dysprosium trinitrate

Cas Number:

10143-38-1

Molecular formula:

Dy.3HNO3

IUPAC Name:

dysprosium trinitrate

Test material form:

solid: crystalline

Details on test material:

- Name of test material (as cited in study report): dysprosium trinitrate (the hydrated form was used as test item)
- Physical state: crystalline solid
- Appearance: white or pale/slightly yellow crystal deliquescent
- Further details on test material confidential.

Specific details on test material used for the study:

- The test material was used as supplied, although it was ground to a fine powder.
- Correction factor: No correction factor for purity of the test item was applied.

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 EPISKINTM (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):
- Batch No.: 16-EKIN-038, Expiry Date: 26 September 2016, used in Experiment I
- Batch No.: 16-EKIN-040, Expiry Date: 10 October 2016, used in Experiment II.
- Date of initiation of testing: Sep 21, 2016 (Experiment I); Oct 5, 2016 (Experiment II)

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 23.2-25.9°C (Experiment I), 23.3-24.8°C (Experiment II)
- 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 PREDI CTION: 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.

VALIDITY CRITERIA
The test is considered valid if:
- The absolute mean OD value of the three negative control tissues is between or equal to 0.6 and 1.5 and the standard deviation value (SD) of the % viability is ≤ 18.
- The mean percentage (relative) viability range for positive controls is ≤ 40% (relative to the negative control) and the standard deviation value (SD) of the % viability is ≤ 18.
- The SD calculated from individual % tissue viabilities of at least three identically treated replicates is < 18.
- The mean OD value of the blank samples (acidified isopropanol) is < 0.1.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 20 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:

5 in Experiment I, 3 in Experiment II

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean of 3 replicates

Value:

98.2

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 (non specific colour % was calculated to be 0.9% but because this value is below 5% adidtional data calculation was not necessary)

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 (Experiment II)

Additional control	Optical Density (OD)			NSC %
		measured	blank corrected
treated with dysprosium trinitrate	1	0.058	0.013
	2	0.047	0.002
	mean	-	0.007	0.9

Notes: mean blank value was 0.045. Optical density means the mean value of the duplicate wells for each sample (rounded to three decimal places).

Optical density and the calculated relative viability % of the samples (experiment I)

substance	optical density (OD)			viability (% RV)
		measured	blank corrected
negative control: phosphate buffered saline	1	0.884	0.835	97.8
	2	0.794	0.745	87.2
	3	1.031	0.982	115.0
	mean	-	0.854	100.0
positive control: 5% (w/v) SDS solution	1	0.070	0.021	2.5
	2	0.087	0.039	4.5
	3	0.087	0.038	4.5
	mean	-	0.033	3.8
test item: dysprosium trinitrate	1	0.805	0.756	88.5
	2	0.804	0.756	88.5
	3	1.005	0.957	112.0
	4	0.876	0.827	96.8
	5	0.947	0.899	105.2
	mean	-	0.839	98.2

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Following exposure with dysprosium trinitrate, the mean cell viability was 98.2% compared to the negative control. This is above the threshold of 50%, therefore the test item was considered as being non-irritant to skin. The experiment met the validity criteria, therefore the study was considered to be valid. Based on these results, the test item is considered not classified according to the CLP Regulation.