Tellurium dioxide

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-09-24 to 2012-12-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Objective of study:

bioaccessibility (or bioavailability)

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Tellurium dioxide

EC Number:

231-193-1

EC Name:

Tellurium dioxide

Cas Number:

7446-07-3

Molecular formula:

O2Te

IUPAC Name:

tellurium dioxide

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): Tellurium dioxide

Radiolabelling:

no

Administration / exposure

Details on study design:

The objective of this study is to assess the dissolution of chemical compounds in artificial alveolar fluid.
The test media is selected to simulate relevant human-chemical interactions (as far as practical), i.e. entering the human body by inhalation. The amount dissolved of the test item is specified by the mass concentration of the substance in the test media under the applied test conditions. The total amount dissolved will be determined by measuring the total concentrations of dissolved tellurium.

Results and discussion

Bioaccessibility (or Bioavailability)

Bioaccessibility (or Bioavailability) testing results:

Dissolved mean tellurium concentrations in alveolar fluid at a loading of 20 mg/L were measured to be:
249.7 ± 7 mg/L after 2 hours (Te)
322.9 ± 25.4 mg/L after 5 hours (Te)
586.6 ± 21.2 mg/L after 24 hours (Te)
799.1 ± 7.3 mg/L after 72 hours (Te)

Any other information on results incl. tables

Dissolved Te concentrations in test vessels and method blanks

sample	total Te conc. [mg/L]	mean Te conc. per vessel ± range [mg/L]	mean Te conc. all vessels ± SD [mg/L]	LOD [mg/L]	LOQ [mg/L]
2h 1a	242.1	243.8 ± 2.3	249.7 ± 7	0.11	0.38
2h 1b	245.4
2h 2a	255.3	255.7 ± 0.5
2h 2b	256.0
5h 1a	299.8	301.0 ± 1.6	322.9 ± 25.4	0.11	0.38
5h 1b	302.1
5h 2a	345.1	344.9 ± 0.4
5h 2b	344.6
24h 1a	575.2	573.4 ± 2.6	586.6 ± 21.2	0.65	2.16
24h 1b	571.5
24h 2a	581.9	599.9 ± 25.4
24h 2b	617.8
72h 1a	801.3	803.7 ± 3.3	799.1 ± 7.3	0.65	2.16
72h 1b	806.0
72h 2a	800.1	794.5 ± 8.0
72h 2b	788.8
2h BW 1a	< LOD			0.11	0.38
2h BW 1b	< LOD
2h BW 2a	< LOD
2h BW 2b	< LOD
5h BW 1a	< LOD			0.11	0.38
5h BW 1b	< LOD
5h BW 2a	< LOD
5h BW 2b	< LOD
24h BW 1a	< LOD			0.65	2.16
24h BW 1b	< LOD
24h BW 2a	< LOD
24h BW 2b	< LOD
72h BW 1a	< LOD			0.65	2.16
72h BW 1b	< LOD
72h BW 2a	< LOD
72h BW 2b	< LOD

LODs (limit of detection) and LOQs (limit of quantification) depend on calibration range.A calibration with an optimal concentration range for samples was performed before each measurement series. Therefore theses limits vary. Three measurement series were performed to quantify Te concentrations.

In the vessels the pHs were not stable over the course of the test. At the start of the study a pH of 8.5 and 8.6 were measured in the two test vessles. After 72 hours the pH value was approx. 9.3.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): other: mean dissolved tellurium concentration in artificial alveolar fluid
The following dissolved mean tellurium concentrations were measured in artificial alveolar fluid at a loading of 20 g/L:
249.7 ± 7 mg/L after 2 hours (Te)
322.9 ± 25.4 mg/L after 5 hours (Te)
586.6 ± 21.2 mg/L after 24 hours (Te)
799.1 ± 7.3 mg/L after 72 hours (Te)

Executive summary:

A study was performed to assess the dissolution of tellurium dioxide in artificial alveolar fluid. The test media is selected to simulate relevant human-chemical interactions (as far as practical), i.e. entering the human body by inhalation.

The Test was performed on the basis of the guidance for OECD-Series on testing and assessment Number 29 and on Stopford et al., 2004.

Test conditions: Artificial alveolar fluid,one single loading of the test substance,measurements of dissolved tellurium after 2, 5, 24 and 72 hours of agitation at 37°C.

The test was performed in duplicate vessels with one single loading of the test substance, 20 g/L (10.00 g / 500 mL in vessel 1 and 2, respectively). The vessels were agitated in an incubation cabinet at 100 rpm at 37 ± 2 °C. During the test pH values were monitored,

in the vessels the pHs were not stable and always lower (0.2 – 0.3 units) in method blanks compared to pHs in test item loaded vessels.

Solved tellurium was quantified by ICP-OES.

The following dissolved mean tellurium concentrations were measured in artificial alveolar fluid:

249.7 ± 7 mg/L after 2 hours (Te)

322.9 ± 25.4 mg/L after 5 hours (Te)

586.6 ± 21.2 mg/L after 24 hours (Te)

799.1 ± 7.3 mg/L after 72 hours (Te)

The percentage of Te in TeO2 is 79.95 %. Therefore the amount of dissolved tellurium dioxide is calculated:

312.3 ± 8.8 mg/L after 2 hours (Tellurium dioxide)

403.9 ± 31.8 mg/L after 5 hours (Tellurium dioxide)

733.7 ± 26.5 mg/L after 24 hours (Tellurium dioxide)

999.4 ± 9.1 mg/L after 72 hours (Tellurium dioxide)

The maximum percentage after 72 hours is calculated to be 5 % dissolved tellurium dioxide in relation to loading.