Tantalum pentachloride

Endpoint summary

Description of key information

Tantalum pentachloride was tested corrosive in an in vitro test using the EPISKIN model, a reconstructed three-dimensional human skin model, according to OECD 431. 

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-01-22 to 2015-03-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))

Deviations:

no

Principles of method if other than guideline:

In vitro; highly differentiated 3D tissue model consisting of normal, human-derived epidermal keratinocytes

GLP compliance:

yes (incl. QA statement)

Type of coverage:

open

Preparation of test site:

other: dried thoroughly by patting

Vehicle:

unchanged (no vehicle)

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 20+/- 2 mg (52.6 mg/cm²)

VEHICLE
- No vehicle due to the instability of the test substance in the presence of water

Duration of treatment / exposure:

3 min, 1 and 4 h

Observation period:

not applicable

Number of animals:

not applicable

Details on study design:

TEST SITE
- Area of exposure: directly atop

REMOVAL OF TEST SUBSTANCE
- Washing (if done): 15 times with 25 ml PBS
- Time after start of exposure: 3 min, 1 h and 4 h

SCORING SYSTEM:
Corrosivity potential of the test item will be predicted from the relative mean tissue viabilities obtained after 3 min, 1 h and 4 h treatment compared to the negative control tissues concurrently treated with 0.9% NaCl solution (=100%).
A test item is classified "non-corrosive" if relative tissue viability after 4 h treatment is not decreased to less than 35 % of the corresponding negative control tissues.
A test item is classified "corrosive" (in accordance with UN GHS "Category 1") in any case, if the relative tissue viability after 4 h treatment is decreased below 35%; if viability is reduced to less than 35% after 4 h treatment and to more than 35% after 1 h treatment, or to less than 35% viability after 1 h but not more than 35% after 3 min treatment, the test item is classified as corrosive, in accordance with optional UN GHS sub-category 1b/C.
A test item with decreases viability below 35% after 3 min treatment is classified as corrosive in accordance with optional UN GHS sub-category 1A.

Irritation / corrosion parameter:

other: other: mean relative tissue viability [%]

Value:

74

Remarks on result:

other:

Remarks:

Basis: mean duplicates. Time point: 3 min. Max. score: 100.0. Remarks: max score = 100 % viability, obtained by negative control. (migrated information)

Irritation / corrosion parameter:

other: other: mean relative tissue viability [%]

Value:

29

Remarks on result:

other:

Remarks:

Basis: mean duplicates. Time point: 1 h. Max. score: 100.0. Remarks: max score= 100% viability, obtained by negative control. (migrated information)

Irritation / corrosion parameter:

other: other: mean relative tissue viability

Value:

4

Remarks on result:

other:

Remarks:

Basis: mean duplicates. Time point: 4 h. Max. score: 100.0. Remarks: max score = 100% viability, obtained by negative control. (migrated information)

Irritation / corrosion parameter:

other: other: mean relative tissue viability [%]

Value:

5

Remarks on result:

other:

Remarks:

Basis: mean duplicates. Time point: 4h. Max. score: 100.0. Remarks: positive control; max score= 100% viability, obtained by negative control. (migrated information)

Pre-Experiments:

The mixture of 20 mg Tantalum pentachloride per 1 mL MTT medium showed no reduction of MTT as compared to the solvent. The medium turned yellow and insoluble residues of the test item were observed. The test item was coloured slightly pink but the mixture did not turn blue/purple.

The mixture of 10 mg Tantalum pentachloride per 300 mL water showed no colouring as compared to the solvent.

Results of the experiment:

Table 1: Results of 3 min. Experiment
Name	Negative Control		Test Item
Tissue	1	2	1		2
Absolute OD570– values (raw data)	1.118	0.999	0.793		0.807
	1.102	0.965	0.765		0.794
Mean OD570 (mean of 2 aliquots per tissue)	1.110	0.982	0.779		0.800
Mean OD570 (blank corrected)	1.064	0.937	0.733		0.755
Total mean OD570 (mean of 2 replicate tissues, blank corrected)	1.000*		0.744
Relative tissue viability (%)	106.4	93.6	73.3	75.5
Mean relative tissue viability (%)	100		74
Difference of relative tissue viability (%)	12.8		2.2
* corrected mean OD570 of the negative control corresponds to 100% absolute tissue viability *** difference between each two replicates is ≤ 30% (in the range of 20-100% viability and for ODs >0.3)

Table 2: Results of 60 min. Experiment
Name	Negative Control		Test Item
Tissue	1	2	1		2
Absolute OD570– values (raw data)	1.036	1.002	0.089		0.575
	1.030	1.012	0.092		0.575
Mean OD570 (mean of 2 aliquots per tissue)	1.033	1.007	0.090		0.575
Mean OD570 (blank corrected)	0.988	0.961	0.045		0.530
Total mean OD570 (mean of 2 replicate tissues, blank corrected)	0.975*		0.287
Relative tissue viability (%)	101.3	98.7	4.6	54.3
Mean relative tissue viability (%)	100		29
Difference of relative tissue viability (%)***	2.7		49.7
* corrected mean OD570 of the negative control corresponds to 100% absolute tissue viability *** difference between each two replicates is ≤ 30% (in the range of 20-100% viability and for ODs >0.3) – (criterion failed for the test item treated replicates)

Table 3: Results of 4h Experiment
Name	Negative Control		Test Item		Positive Control
Tissue	1	2	1	2	1	2
Absolute OD570– values (raw data)	0.983	0.939	0.085	0.075	0.091	0.093
	0.963	0.887	0.084	0.083	0.095	0.096
Mean OD570(mean of 2 aliquots per tissue)	0.973	0.913	0.084	0.079	0.093	0.094
Mean OD570(blank corrected)	0.927	0.867	0.039	0.034	0.047	0.049
Total mean OD570(mean of 2 replicate tissues, blank corrected)	0.897*		0.036		0.048
Relative tissue viability (%)	103.4	96.6	4.3	3.7	5.3	5.5
Mean relative tissue viability (%)	100		4		5**
Difference of relative tissue viability (%)***	6.7		0.6		0.2
* corrected mean OD570of the negative control corresponds to 100% absolute tissue viability ** mean relative tissue viability of the two positive control tissues of the 4h treatment period is ≤ 20% *** difference between each two replicates is ≤ 30% (in the range of 20-100% viability and for ODs >0.3)

Table 4: Test acceptance criteria

	value	cut off	pass/fail
Mean OD570 nmblank	0.046	<0.1	pass
Mean absolute OD570 nmNC (4h experiment)	0.897	0.6-1.5	pass
Mean absolute OD570 nmNC (60 min. experiment)	0.975	0.6-1.5	pass
Mean absolute OD570 nmNC (3 min. experiment)	1.000	0.6-1.5	pass
Mean relative viability PC (%) (4h experiment)	5%	≤20%	pass
Max. difference of tissue viability	49.7%	≤30%	fail

Interpretation of results:

corrosive

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Tantalum pentachloride was classified as corrosive under conditions of a validated EPISKIN-SM in vitro test.

Executive summary:

In an in vitro skin corrosion study, the reconstituted three-dimensional human skin model EPISKIN-SM^TM was topically exposed to 20 mg of Tantalum pentachloride (99.9%) for 3 min, 1 h and 4 h according to OECD guideline 431. After exposure the tissue was washed with PBS and tissue viability was assessed using the MTT reduction assay.

Physiological saline served as negative control, corresponding to 100 % tissue viability. As a positive control glacial acetic acid was used. Measurements were performed in duplicates and mean values were calculated.

In this study, Tantalum pentachloride is skin corrosive, based on a mean tissue viability of less than 35% after 60 min, but not after 3 min. Tantalum pentachloride is classified as corrosive in accordance with CLP sub-category 1B/C.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Tantalum pentachloride showed corrosive effects in an in vitro study using EPISKIN-SM TM, a reconstructed three-dimensional human skin model. In this in vitro assay, corrosive potential is assessed by tissue viability after exposure of EPISKIN-SM TM to the substance of interest. Treatment periods are 3 min, 1 h and 4 h. The viability of the tissue is assessed by MTT. Cut-off criteria for corrosive potential is a reduction of the tissue viability to less than 35% from the tissue viability of a control, which corresponds to 100%.

In this test the mean relative tissue viability (% negative control) was reduced below 35% (29%) after 1 h treatment and to not less than 35% (74%) after 3 min treatment. After 4 h treatment relative mean tissue viability was reduced to 4%.

The controls confirmed the validity of the study. The mean OD 570nm of the two negative control tissues was between 0.6 and 1.5 for each exposure period. The mean relative tissue variability (% negative control) of the positive control was ≤ 30% (0.2%-12.8%).

Justification for selection of skin irritation / corrosion endpoint:
GLP guideline study

Effects on skin irritation/corrosion: corrosive

Justification for classification or non-classification

Based on the results obtained from an in vitro skin irritation/corrosion test according to OECD 431, tantalum pentachloride is classified as corrosive in accordance with CLP sub-category 1B/C. Due to rapid hydrolysis and subsequent generation of HCl, classification for H335 is warranted, which is in line with the harmonised classification of hydrochloric acid.