Titanium carbide

Endpoint summary

Description of key information

Dermal irritation was assessed according to OECD 439; eye irritation was assessed in vitro (BOCP; OECD 437) and confirmed in vivo (OECD 405). 

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-08-22 to 2012-08-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Standard GLP study performed according to the OECD Guideline 439 (2010).

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

human

Type of coverage:

other: non-relevant, in vitro study with the model EPISKIN-SM

Preparation of test site:

other: non-relevant, in vitro study with the model EPISKIN-SM

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 10 mg (26.3 mg/cm2)
The test material was applied after application of distilled water (5 µl) to the reconstructed human epidermis (Rhe), so as to achive the maximum possible contact.

Duration of treatment / exposure:

15 ± 0.5 min and 42 h post-incubation

Details on study design:

Pre-test: the non-specific MTT-reducing capacity of Titanium carbide was assessed prior to the intitiation of the main study.
Main test: the tissues of the EPISKIN-SM kit were incubated, and therafter treated with each dose group in triplicate. Phosphate buffered saline was used as negative control and 5% sodium dodecyl sulfate in distilled water as positive control. Exposure lasted 15 min and after washing with PBS a 42 hpost-exposure incubation followed. After incubation 2 ml of MTT were transferred in each well. Incubation of 3 h followed. The OD was measured at 550 nm.

Barrier function and morphology, were provided by the Rhe model supplier to assure the proper functioning of the tissues.

Irritation / corrosion parameter:

other: other: relative mean tissue viability

Remarks on result:

other:

Remarks:

Remarks: The results are presented in the table below. (migrated information)

Irritant / corrosive response data:

See below 'any other information on results incl. tables'.

Table 1: Experimental results of the EPISKIN-SM test after application of Titanium carbide powder.

Name	Negative Control			Positive Control			Test Item
Tissue	1	2	3	1	2	3	1	2	3
Mean OD550of 3 replicate tissues (blank-corrected	0.742			0.184			0.740
SD OD550	0.052			0.080			0.077
Relative tissue viabilities (%)	100.2	104.6	95.2	37.6	21.6	15.1	105.8	105.6	87.9
Mean relative tissue viability (%)	100			25			100
SD tissue viability (%)	4.7			11.6			10.3
CV (% viability)	4.7			46.8			10.3

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Titanium carbide is no irritant in the human skin model EPISKIN-SM.

Executive summary:

In this in vitro dermal irritation study with the three-dimensional human skin model EPISKIN-SM, the irritation potential of Titanium carbide was examined. The test substance was applied topically on the tissue for 15 min, and thereafter the exposed tissue culture was incubated for 42 h. A positive and a negative control were used. The determination of cytotoxic effects was performed with the MTT assay. Irritation potential of the test susbstance was determined based on the cytotoxicity observed (mean tissue viability). The results revealed a mean relative tissue viability higher than 50%, and hence, the test substance is not a skin irritant under the conditions of this test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November - December 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, 97633 Sulzfeld, Germany
- Age at study initiation: approximately 13 weeks old
- Weight at study initiation: > 2 kg
- Housing: ABS - plastic rabbit cages, floor 4200 cm²
- Diet: Free access to autoclaved hay and to Altromin 2123 maintenance diet for rabbits (lot no. 1516), rich in crude fibre
- Water: Free access to tap water (drinking water, municipal residue control, microbiological controls at regular intervals)
- Certificates of food, water and bedding are filed at BSL BIOSERVICE
- Acclimation period: at least 5 days under laboratory conditions

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 ± 3 °C (recommendations of TVT, GV-SOLAS)
- Humidity (%): 55 ± 10 °C
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 h : 12 h

TVT = TVT Tierärztliche Vereinigung für Tierschutz, Merkblatt 127 zur Tiergerechten Haltung von Versuchskaninchen, 2010
GV-SOLAS = Planung, Struktur von Versuchstierbereichen tierexperimentell tätiger Institutionen; Veröffentlichung GV-SOLAS (Gesellschaft für Versuchstierkunde, Society for Laboratory Animal Science), Mai 1988

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated eye of each animal served as control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 g

Duration of treatment / exposure:

72 h (the treated eye was not rinsed 24 hours after the application.)

Observation period (in vivo):

72 h

Number of animals or in vitro replicates:

3

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing: none

SCORING SYSTEM: see "Any other information on materials and methods incl. table"

TOOL USED TO ASSESS SCORE: fluorescein

Irritation parameter:

conjunctivae score

Basis:

other: animals #1, #2, and #3

Time point:

other: 1, 24, 48, 72 h (mean values)

Score:

>= 0.33 - <= 0.67

Max. score:

1

Reversibility:

fully reversible

Remarks on result:

other: For details see "Any other information on results incl. tables"

Irritation parameter:

chemosis score

Basis:

other: animals #1, #2, and #3

Time point:

other: 1, 24, 48, 72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

iris score

Basis:

other: animals #1, #2, and #3

Time point:

other: 1, 24, 48, 72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

cornea opacity score

Basis:

other: animals #1, #2, and #3

Time point:

other: 1, 24, 48, 72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritant / corrosive response data:

- First time of effects, all animals: 1 hour post-application redness grade 1
- Last time of effects:
* animal no. 1: 48 hours post-application redness grade 1
* animal no. 2 and no. 3: 24 hours post-application redness grade 1
- Reversibility of the observed effects:
* animal no. 1: the changes were fully reversible within 72 hours post-application
* animal no. 2 and no. 3: the changes were fully reversible within 48 hours post-application

Table 2: Mean Values of Eye Irritation Scores – (24, 48, 72 Hour Reading)

Animal No.	Sex	Conjunctival Redness	Conjunctival Chemosis	Iris Cornea	Opacity
1	female	0.67	0.00	0.00	0.00
2	female	0.33	0.00	0.00	0.00
3	female	0.33	0.00	0.00	0.00

 

Evaluation of Results

Individual reactions of each animal were recorded at each time of observation. Nature, severity and duration of all lesions observed were described. For the calculation only the 24, 48 and 72-hour readings were used.

On the basis of the test results, the test substance was classified in any of the following classes in conformity with the criteria given in Annex VI to Commission Directive 2001/59/EC:

R36 Irritating to eyes:

Substances and preparations which, when applied to the eye of the animal, cause significant ocular lesions which occur within 72 hours after exposure and which persists for at least 24 hours.

Ocular lesions are significant if the mean scores of the eye irritation test cited in Annex B.5 to Commission Regulation (EC) No. 440/2008, L 142 have any of the following values:

- corneal opacity ≥ 2 but < 3

- iris lesion ≥ 1 but ≤ 1.5,

- redness of the conjunctiva ≥ 2.5,

- oedema of the conjunctiva (chemosis) ≥ 2,

or, in case where Annex B.5 test have been completed using three animals if the lesions, on two or more animals, are equivalent to any of the above values except that for iris lesion the value should be ≥ 1 but < 2 and for redness of the conjunctiva the value should be ≥ 2.5. In both cases all scores at each of the reading times (24, 48 and 72 hours) for an effect should be used in calculating the respective mean values.

- Substances or preparations which cause significant ocular lesions, based on practical experience in humans.

- Organic peroxides except where evidence to the contrary is available.

R41 Risk of serious damage to eyes

Substances and preparations which, when applied to the eye of the animal cause severe ocular lesions which occur within 72 hours after exposure and which persist for at least 24 hours. O

cular lesions are severe if the means of the scores of the eye irritation test cited in Annex B.5 to Commission Regulation (EC) No. 440/2008, L 142 have any of the values:

- cornea opacity ≥ 3,

- iris lesion > 1.5.

The same shall be the case where the test has been completed using three animals if these lesions, on two or more animals, have any of the values:

- cornea opacity ≥ 3,

- iris lesion = 2.

In both cases all scores at each of the reading times (24, 48 and 72 hours) for an effect should be used in calculating the respective mean values.

Ocular lesions are also severe when they are still present at the end of the time of observation.

Ocular lesions are also severe if the substance or preparation causes irreversible colouration of the eyes.

- Substances and preparations which cause severe ocular lesions, based on practical experience in humans.

Note:

When a substance or preparation is classified as corrosive and assigned R34 or R35, the risk of severe damage to eyes is considered implicit and R41 is not included in the label.

On the basis of the test results, the following risk phrases shall be assigned in conformity with the criteria given in Annex I of Regulation (EC) 1272/2008:

Eye irritant Category 1:

Irreversible effects on the eyes / serious damage to the eyes An eye irritant category 1 is a test material that produces:

- at least in one animal effects on the cornea, iris or conjunctiva that are not expected to reverse or that have not fully reversed within 21 days; and/or

- at least in 2 of 3 animals, a positive response of

(i) corneal opacity 3; and/or

(ii) iritis > 1.5

calculated as the mean scores following the grading at 24, 48 and 72 hours after instillation of the test material.

Eye irritant Category 2:

Reversible effects on the eyes/Irritating to the eyes

An eye irritant category 2 is a test material that produces:

- at least in 2 of 3 animals, a positive response of

(i) corneal opacity 1; and/or

(ii) iritis 1; and/or

(iii) conjunctival redness 2; and/or

(iv) conjunctival oedema (chemosis) 2

calculated as the mean scores following the grading at 24, 48 and 72 hours after instillation of the test material, and which fully reverse within an observation period of 21 days.

On the basis of the test results, the following risk phrases may be assigned in conformity with the criteria given in GHS - Globally Harmonized System of Classification and Labelling of Chemicals, third revised edition, July 2009:

Category 1: An eye irritant Category 1 (irreversible effects on the eye) is a test material that produces:

- at least in one animal effects on the cornea, iris or conjunctiva that are not expected to reverse or that have not fully reversed within 21 days; and/or

- at least in 2 of 3 animals, a positive response of

(i) corneal opacity 3; and/or

(ii) iritis > 1.5

calculated as the mean scores following the grading at 24, 48 and 72 hours after instillation of the test material.

Category 2A: An eye irritant Category 2A (irritating to eyes) is a test material that produces:

- at least in 2 of 3 animals, a positive response of

(i) corneal opacity 1; and/or

(ii) iritis 1; and/or

(iii) conjunctival redness 2; and/or

(iv) conjunctival oedema (chemosis) ≥ 2

calculated as the mean scores following the grading at 24, 48 and 72 hours after instillation of the test material, and which fully reverse within 21 days.

Category 2B: Within this category an eye irritant is considered mildly irritating to eyes (Category 2B), when the effects listed above are fully reversible within 7 days of observation.

Results:

After the application into the eyes of three female NZW rabbits the test item produced irritant but no corrosive effects (see Tables 3 to 5).

Neither mortalities nor significant clinical signs of toxicity were observed (Table 6).

The eyes were not rinsed after the application.

Upon fluorescein examinations at the end of the observation period of 72 hours no corneal lesions were found in any animal.

Conjunctival redness was observed in all animals and are individually described in Tables 3 to 6.

Table 3: Eye Irritation Scores – Animal No. 1

Single Data
	Time Post-Application				Average Score (24, 48 and 72 hours)
	1 hour	24 hours	48 hours	72 hours
	T/C	T/C	T/C	T/C
Conjunctival Redness	1/0	1/0	1/0	0/0	0.67
Conjunctival Chemosis	0/0	0/0	0/0	0/0	0
Iris	0/0	0/0	0/0	0/0	0
Cornea	0/0	0/0	0/0	0/0	0

T = Test item, C = control

Table 4: Eye Irritation Scores – Animal No. 2 

Single Data
	Time Post-Application				Average Score (24, 48 and 72 hours)
	1 hour	24 hours	48 hours	72 hours
	T/C	T/C	T/C	T/C
Conjunctival Redness	1/0	1/0	0/0	0/0	0.33
Conjunctival Chemosis	0/0	0/0	0/0	0/0	0
Iris	0/0	0/0	0/0	0/0	0
Cornea	0/0	0/0	0/0	0/0	0

T = test item, C = control

Table 5: Eye Irritation Scores – Animal No. 3

Single Data
	Time Post-Application				Average Score (24, 48 and 72 hours)
	1 hour	24 hours	48 hours	72 hours
	T/C	T/C	T/C	T/C
Conjunctival Redness	1/0	1/0	0/0	0/0	0.33
Conjunctival Chemosis	0/0	0/0	0/0	0/0	0
Iris	0/0	0/0	0/0	0/0	0
Cornea	0/0	0/0	0/0	0/0	0

T = test item, C = control

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In this study, titanium carbide is not irritant to the eye.

Executive summary:

In a primary eye irritation study according to OECD 405, 0.1 g of titanium carbide was instilled into the conjunctival sac of one eye each of three female New Zealand White rabbits (age approximately 13 weeks). Eyes were not washed. Animals were observed for a total of 72 hours. Irritation was scored by evaluating conjunctival redness, conjunctival chemosis, iris, and cornea

Only slight effects have been observed which were fully reversible within 72 hours. Neither mortalities nor significant clinical signs of toxicity were observed. In this study, titanium carbide is not an eye irritant.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Titanium carbide was tested negative in an in vitro dermal irritation study with the three-dimensional human skin model EPISKIN-SM (OECD 439). The determination of cytotoxic effects was performed with the MTT assay. Irritation potential of the test substance was determined based on the cytotoxicity observed (mean tissue viability). The results revealed mean relative tissue viability higher than 50%, and hence, the test substance is not a skin irritant under the conditions of this test.

The eye irritancy potential was investigated in the bovine corneal opacity and permeability assay (BCOP) according to OECD 437. This in vitro test method can be used to classify substances as “ocular corrosives and severe irritants” only. The mean in vitro irritation score was 2.19. Thus, titanium carbide is not classified as severe eye irritant.

The irritation potential was further evaluated in a primary eye irritation study according to OECD 405. Titanium carbide was instilled into the conjunctival sac of one eye each of three female New Zealand White rabbits. Only slight effects have been observed which were fully reversible within 72 hours. Neither mortalities nor significant clinical signs of toxicity were observed. In this study, titanium carbide is not an eye irritant.

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

Justification for selection of eye irritation endpoint:
GLP Guideline study in vivo

Justification for classification or non-classification

Titanium carbide is not considered an irritant to the skin or to the eye in any of the assays of a standard testing battery.