Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-11-13 to 2018-01-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Objective of study:
bioaccessibility
Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
This report measured bioaccessibility of Ytterbium stabilized Zirconium and Hafnium Oxide in in different artificial media: gastric juice, lysosomal, alveolar and perspiration fluids; representing ingestion, inhalation and dermic contact routes of exposure in humans.
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
- Batch No.: 7170403
- Source: H.C. Starck Surface Technology and Ceramic Powders GMBH, Germany
Radiolabelling:
not specified

Test animals

Details on test animals and environmental conditions:
Not applicable

Administration / exposure

Route of administration:
other: representing ingestion, inhalation and dermal routes of exposure in humans
Vehicle:
unchanged (no vehicle)
Details on exposure:
- Gastric bio-elution test: Metals or metal compounds are subjected to a media that mimics gastric juice, in terms of pH and body temperature (pH 1.5 and 37 °C), for an exposure time of 1 hour with agitation. Then the substances are incubated for another hour without agitation, before aliquots are taken, filtered and bio-accessible metals are quantified with an ICP-MS spectrometer.

- Lysosomal bio-elution test: Metals or metal substances are subjected to a media pH 4.5 – 5.0 that mimics intracellular conditions of phagocytosis in alveolar and interstitial macrophages. A bio-elution test of 3 days at 37 °C and 171 rpm agitation rate was performed. Samples are taken at 2, 24 and 72 hours of incubation, filtered and bio-accessible metals are quantified with an ICP-MS spectrometer.

- Alveolar bio-elution test: Metals or metal substances are subjected to a media that mimics alveolar fluid in the lung for 3 days at 37 °C and 171 rpm agitation rate. Samples are taken at 2, 24 hours and 72 hours of incubation, filtered and bio-accessible are metals quantified with an ICP-MS spectrometer.

- Sweat bio-elution test: Metals or metal substances are subjected to a media that mimics perspiration for 7 days at 30 °C and without agitation. Samples are taken at 24 hours and 168 hours of incubation, filtered and bioaccessible metals are quantified with an ICP-MS spectrometer.
Doses / concentrationsopen allclose all
Dose / conc.:
0.2 other: g / L
Remarks:
Gastric bio-elution test
Dose / conc.:
2 other: g / L
Remarks:
Lysosomal bio-elution, Alveolar bio-elution and sweat bio-elution test
No. of animals per sex per dose:
Not applicable
Positive control:
Not applicable
Details on study design:
- Gastric bio-elution test procedure:
A volume of 50 ml of gastric medium is added to 6 glass flasks of 250 ml. The vessels are pre-incubated in an orbital shaker at about 60 rpm, until equilibrium temperature has been reached (37 ºC), pH and dissolved Oxygen are measured. Before adding the metal substance, 15 mL samples are withdrawn per flask, filtered through 0.2 μm PTFE membranes and separate to measure the metal concentration (time 0, detection of possible contamination). Fresh media is added back to complete the 50 ml. In three of the flasks the metal substance is added at 0.2 g/L sample loading and the agitation rate set to 171 rpm. The 2 hours of incubation are performed in dark conditions, the first hour with agitation and the second hour without agitation. As soon as the incubation time is completed, one sample is taken from each flask and filtered through 0.2 μm PTFE membranes. To preserve sample integrity: After each sample is collected, the samples are stored at 4 °C
in dark conditions until the analysis is performed (within 2 weeks).

- Lysosomal bio-elution test procedure:
A volume of 50 ml of lysosomal media is added to 18 glass flasks of 250 ml. The vessels are pre-incubated in an orbital shaker at about 60 rpm, until equilibrium temperature has been reached (37 ºC), pH and dissolved Oxygen are measured. Before adding the metal substance, 15 mL samples are withdrawn per flask, filtered through 0.2 μm PTFE membranes and separate to measure the metal concentration (time 0, detection of possible contamination). Fresh media is added back to complete the 50 ml. In nine of the flasks the metal substance is added at 2 g/L sample loading and the agitation rate set to 171 rpm. The 3 days of incubation are performed in dark conditions. After 2 hours of incubation one 15 ml aliquot is taken from each of 3 blank flasks and 3 sample flasks. The
vessels are discarded and the aliquots, filtered through 0.2 μm PTFE membranes. The sampling procedure is repeated at 24 and 72 hours of incubation. To preserve sample integrity: After each sample is collected, 3 drops of concentrated Nitric Acid (high purity, ultra trace quality) are added. The samples are stored at 4 °C in dark conditions until the analysis is performed (within 2 weeks).

- Alveolar bio-elution test procedure:
A volume of 50 ml of alveolar media is added to 18 glass flasks of 250 ml. The vessels are pre-incubated in an orbital shaker at about 60 rpm, until equilibrium temperature has been reached (37 ºC), pH and dissolved Oxygen are measured. Before adding the metal substance, 15 mL samples are withdrawn per flask,filtered through 0.2 μm PTFE membranes and separate to measure the metal concentration (time 0, detection of possible contamination). Fresh media is added back to complete the 50 ml. nine of the flasks the metal substance is added at 2 g/L sample loading and the agitation rate set to 171 rpm. The 3 days of incubation are performed in dark conditions. After 2 hours of incubation one 15 ml aliquot is taken from each of 3 blank flasks and 3 sample flasks. The vessels are discarded and the aliquots, filtered through 0.2 μm PTFE membranes. The sampling procedure is repeated at 24 and 72 hours of incubation. To preserve sample integrity: After each sample is collected, 3 drops of concentrated Nitric Acid (high purity, ultra trace quality) are added. The samples are stored at 4 °C in dark
conditions until the analysis is performed (within 2 weeks).

- Sweat bio-elution test procedure:
A volume of 50 ml of perspiration media is added to 12 glass flasks of 250 ml. The vessels are pre-incubated in an orbital shaker at about 60 rpm, until equilibrium temperature has been reached (30 ºC), pH and dissolved Oxygen is measured. Before adding the metal substance, 15 mL samples are withdrawn per flask, filtered through 0.2 μm PTFE membranes and separate to measure the metal concentration (time 0, detection of possible contamination). Fresh media is added back to complete the 50 ml. In six of the flasks the metal substance is added at 2 g/L sample loading and the vessel swirled to mix the compound with the media. The 7 days of incubation without agitation are performed in dark conditions. After 24 hours of incubation one 15 ml aliquot is taken from each of 3 blank flasks and 3 sample flasks. The vessels are discarded and the aliquots, filtered through 0.2 μm PTFE membranes. The rest of the flasks continue the test until the 7 days of incubation are completed, and once again 15 ml blank and sample aliquots are taken and filtered. To preserve sample integrity: After each sample is collected, 3 drops of concentrated Nitric Acid (high purity, ultra trace quality) are added. The samples are stored at 4 °C in dark conditions until the analysis is performed (within 2 weeks).
Details on dosing and sampling:
Not applicable
Statistics:
Not applicable

Results and discussion

Bioaccessibility

Bioaccessibility testing results:
See Tables under "Any other information on results incl. tables"

Any other information on results incl. tables

Table 1: Perspiration bio-elution test

Perspiration test parameters

Hafnium, µg/L

Hafnium, µg / g

Hf

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean,  µg /g

CV, %

 

Before

30

6.58

BDL

-

-

-

-

 

24

30

6.01

BDL

-

-

-

-

 

168

30

5.55

BDL

-

-

-

-

Perspiration test parameters

Ytterbium, µg/L

Ytterbium µg / g

Yb

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

30

6.58

BDL

-

-

-

-

 

24

30

6.01

3.242

0.32

10

1.621

10

 

168

30

5.55

5.524

0.21

400

2.762

4

Perspiration test parameters

Zirconium, µg/L

Zirconium µg / g

Zr

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

30

6.58

BDL

-

-

-

-

 

24

30

6.01

0.02

0.01

28

-

-

 

168

30

5.55

0.22

0.05

21

0.11

21

Table 2: Alveolar bio-elution test

Alveolar test parameters

Hafnium, µg/L

Hafnium, µg / g

Hf

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

7.45

BDL

-

-

-

-

 

2

37

7.47

BDL

-

-

-

-

 

24

37

7.40

BDL

-

-

-

-

 

72

37

7.29

0.11

0.03

26

-

-

Alveolar test parameters

Ytterbium, µg/L

Ytterbium µg / g

Yb

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

7.45

BDL

-

-

-

-

 

2

37

7.47

0.106

0.08

72

0.053

72

 

24

37

7.40

0.095

0.00

2

0.048

2

 

72

37

7.29

2.846

0.24

8

1.423

8

Alveolar test parameters

Zirconium, µg/L

Zirconium µg / g

Zr

Time, hr

Temp, °C

pH

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

7.45

BDL

-

-

-

-

 

2

37

7.47

0.5

0.34

65

-

-

 

24

37

7.40

1.2

0.34

29

0.6

29

 

72

37

7.29

5.4

1.14

21

2.7

21

Table 3: Lysosomal bio-elution test

Lysosomal test parameters

Hafnium, µg/L

Hafnium, µg / g

Hf

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

4.53

BDL

-

-

-

-

 

2

37

4.50

BDL

-

-

-

-

 

24

37

4.55

0.02

0.006

30

-

-

 

72

37

4.55

0.09

0.005

5

0.04

5

Lysosomal test parameters

Ytterbium, µg/L

Ytterbium µg / g

Yb

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

4.53

0.002

0.001

50

-

-

 

2

37

4.50

2.990

0.192

6

1.495

6

 

24

37

4.55

8.314

0.496

6

4.157

6

 

72

37

4.55

8.943

1.089

12

4.472

12

Lysosomal test parameters

Zirconium, µg/L

Zirconium µg / g

Zr

Time, hr

Temp, °C

pH

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

4.53

BDL

-

-

-

-

 

2

37

4.50

1.5

0.05

3

0.8

3

 

24

37

4.55

4.3

0.10

2

2.2

2

 

72

37

4.55

5.5

0.31

6

2.8

6

Table 4: Gastric bio-elution test

Gastric test parameters

Hafnium, µg/L

Hafnium, µg / g

Hf

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

1.50

BDL

-

-

-

-

 

2

37

1.51

BDL

-

-

-

-

Gastric test parameters

Ytterbium, µg/L

Ytterbium µg / g

Yb

Time, hr

Temp, °C

Ph

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

1.50

BDL

-

-

-

-

 

2

37

1.51

0.485

0.021

4

2.427

4

Gastric test parameters

Zirconium, µg/L

Zirconium µg / g

Zr

Time, hr

Temp, °C

pH

Mean; µg / L

St. Dev

CV, %

Mean

CV, %

 

Before

37

1.50

BDL

-

-

-

-

 

2

37

1.51

0.01

0.006

66

0.05

66

Applicant's summary and conclusion

Conclusions:
The test item showed low solubility.
Executive summary:

In this study, bio-elution tests in four different synthetic media, including: gastric, lysosomal, alveolar and perspiration, were performed to Ytterbium stabilized Zirconium and Hafnium Oxide. The results of the bio-elution tests (table 1), show low solubility of the metallic components of the test item: zirconium, ytterbium and hafnium; in the set of fluids assayed; with the higher metal release values found in artificial lysosomal fluid after 72 hours of incubation, with a solubility of 0.003 % (w/w) for Yb and 0.0004% (w/w) for Zr.