Titanium carbide

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-01-18 to 2012-03-03

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Objective of study:

bioaccessibility (or bioavailability)

Qualifier:

no guideline available

Principles of method if other than guideline:

This report measured bioaccessibility of Titanium carbide in body fluid simulants as a surrogate for bioavailability.

GLP compliance:

no

Radiolabelling:

no

Species:

other: not applicable

Strain:

other: not applicable

Details on test animals or test system and environmental conditions:

Not applicable

Route of administration:

other: In vitro study

Vehicle:

other: not applicable

Details on exposure:

Not applicable

Duration and frequency of treatment / exposure:

Not applicable

Remarks:

Doses / Concentrations:
0.1 g of test substance in 50 mL of simulated fluid

No. of animals per sex per dose / concentration:

Not applicable

Control animals:

other: not applicable

Positive control reference chemical:

Not applicable

Details on study design:

Titanium Carbide was extracted in leaching fluids for different time periods: 2 hrs and 24 hrs in simulated gastric and lysosomal fluid, 24 hrs in simulated interstitial fluid and 12 hrs in artifical perspiration. The extractions were performed using 0.1 gram of sample in 50 ml of simulated fluid. A shaker water bath at a temperature of 37°C was used. All extractions were performed in triplicate. The extracts were analyzed for soluble Titanium using EPA Method #200.7 (ICP). Results were reported as ug Ti/g sample, % Ti/g sample and as % of total available Ti released.

Details on dosing and sampling:

Not applicable

Statistics:

Not applicable

Preliminary studies:

Not applicable

Details on absorption:

Not applicable

Details on distribution in tissues:

Not applicable

Details on excretion:

Not applicable

Metabolites identified:

not measured

Details on metabolites:

Not applicable

Table 1: Soluble Titanium in gastric fluid

Extraction time in h	Weight used	µg Titanium/g Sample	% Titanium release/Titanium content
2	0.1008	1,637	0.20
(dup)	0.1058	1,749	0.22
(trip)	0.1034	1,644	0.21
24	0.1021	4,603	0.58
(dup)	0.1024	4,395	0.55
(trip)	0.1042	4,319	0.54

 

Table 2: Soluble Titanium in simulated interstitial fluid

Extraction time in h	Weight used	µg Titanium/g Sample	% Titanium release/Titanium content
24	0.1027	< 50.0	-
(dup)	0.1004	< 50.0	-
(trip)	0.1024	< 50.0	-

 

Table 3: Soluble Titanium in lysosomal fluid

Extraction time in h	Weight used	µg Titanium/g Sample	% Titanium release/Titanium content
2	0.0992	151	0.02
(dup)	0.0995	151	0.02
(trip)	0.1015	148	0.02
24	0.1029	656	0.08
(dup)	0.0995	678	0.08
(trip)	0.1005	662	0.08

 

Table 4: Soluble Titanium in artificial perspiration

Extraction time in h	Weight used	µg Titanium/g Sample	% Titanium release/Titanium content
12	0.0996	< 50.0	-
(dup)	0.1052	< 50.0	-
(trip)	0.1006	< 50.0	-

 

Conclusions:

The release of Ti ions from TiC is very low in artifical body fluids. More Ti ions are released at acidic pH with up to 0.56 % in simulated gastric acid solution (pH 1.5) and 0.08 % in lysosomal fluid (pH 4.5).

Executive summary:

This report measured bioaccessibility of Titanium Carbide as a surrogate for bioavailability.To do this the soluble Titanium was measured using the EPA method #200.7 (ICP) after incubation of Titanium Carbide in simulated body fluids (simulated gastric fluid, simulated interstitial fluid, simulated lysosomal fluid, and artifical perspiration). Results were reported as ug Ti/g sample, % Ti/g sample and as % of total available Ti released.

Overview of Ti released in the different simulated body fluids:

Medium	t in h	% Ti-release
Simulated gastric fluid	2	0,21 %
	24	0,56 %
Simulated interstitial fluid	24	BDL
Simulated lysosomal fluid	2	0,02%
	24	0,08 %
Artifical perspiration	12	BDL

BDL: Below detection limit. In summary, release of Titanium ions from TiC is higher at acidic pH, even though at a very low degree. The bioavailability in the fluids ranged from BDL (interstitial fluid and artifical perspiration) to 0,56 % (simulated gastric fluid). Thus, the maximum solubility was determined at acidic pH. Based on the results, the bioavailability of Titanium carbide would be expected to be low for all routes of administration.

Description of key information

Bioelution results of titanium carbide in four artificial body fluids which served as a surrogate for bioavailability in different tissues, demonstrated very low release of titanium ions in general.

The amount of soluble titanium was below detection limit in artificial perspiration fluid and simulated interstitial fluid, representing sweat/dermal and interstitial milieus in the deep lung, respectively.

Very limited amounts of soluble titanium could be detected in artificial lysosomal fluid (0.08% titanium release after 24 hours) and simulated gastric fluid (0.56% titanium release after 24 hours).

Additional information

Bioelution results of titanium carbide in four artificial body fluids have been conducted (Kirby Memorial Health Center, 2012).

Titanium carbide was incubated for up to 24 hours in the different fluids (simulated gastric fluid, simulated interstitial fluid, simulated lysosomal fluid and artificial perspiration fluid) and analysed by Inductively Coupled Plasma-Atomic Emission Spectrometry (EPA Method 200.7).

The results after incubation in the different body fluids demonstrated that the release of titanium ions from titanium carbide is very low.

The amount of soluble titanium was below detection limit in artificial perspiration fluid and simulated interstitial fluid, representing sweat/dermal and interstitial milieus, respectively.

Very limited amounts of soluble titanium could be detected in artificial lysosomal fluid (up to 0.08% titanium release after 24 hours) and simulated gastric fluid (up to 0.56% titanium release after 24 hours).

In summary, release of titanium ions from titanium carbide is higher at acidic pH, even though at a very low degree. Based on the results, the bioavailability of titanium carbide would be expected to be low for all routes of administration.