Germanium

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Remarks:

Test according to state-of-the-art operating procedures for testing of metal bioelution.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Objective of study:

bioaccessibility (or bioavailability)

Test guideline

Qualifier:

according to guideline

Guideline:

other: ASTM D5517-07: Standard Test Method for determining the extractability of metals from art materials - ASTM, 2007 (American Society for Testing and Materials).

Principles of method if other than guideline:

The release/dissolution of germanium from germanium metal powder in simulated gastric fluid was measured. The resulting value is termed bio-accessibility, and is defined as the fraction of a substance that is soluble under physiological conditions and therefore potentially available for absorption into systemic circulation. The simulated gastric fluid represents an exposure-relevant exposure route (oral exposure). The compound was introduced as powder in a test item / solution ratio of 200 mg/L during 2 hours.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Germanium

EC Number:

231-164-3

EC Name:

Germanium

Cas Number:

7440-56-4

Molecular formula:

Ge

IUPAC Name:

germanium

Test material form:

solid: particulate/powder

Details on test material:

Batch number: Zwarte C-mal 229-2
Description: Grey Powder
Expiry date: 18 September 2018
Purity: 96.9%
Storage conditions: Controlled room temperature (15-25°C, below 70% RH%)
Safety precautions: Routine safety precautions (lab coat, gloves, safety glasses, face mask) for unknown materials were applied to assure personnel health and safety.

Specific details on test material used for the study:

batch used = Zwarte C-mal 229-1 (= filtered Zwarte C-mal 229-2, to obtain particles below 100 µm)

Results and discussion

Preliminary studies:

not applicable

Main ADME results

Main ADME results 1

Type:

other: bioaccessibility

Results:

gastric fluid (0hours): as %Ge released of total Ge content: 0.13

Main ADME results 2

Type:

other: bioaccessibility

Results:

gastric fluid (1hours): as %Ge released of total Ge content: 4.27

Main ADME results 3

Type:

other: bioaccessibility

Results:

gastric fluid (2hours): as %Ge released of total Ge content: 5.83

Toxicokinetic / pharmacokinetic studies

Details on absorption:

not applicable

Details on distribution in tissues:

not applicable

Details on excretion:

not applicable

Metabolite characterisation studies

Metabolites identified:

not measured

Details on metabolites:

not applicalbe

Bioaccessibility (or Bioavailability)

Bioaccessibility (or Bioavailability) testing results:

gastric fluid (0hours): as %Ge released of total Ge content: 0.13
gastric fluid (1hours): as %Ge released of total Ge content: 4.27
gastric fluid (2hours): as %Ge released of total Ge content: 5.83

Any other information on results incl. tables

Germanium, loading 0.2 g/L (= 1.19 m²/L surface loading)
		2-h gastric at pH 1.2
Analyte		xavg± sbetween	CV
germanium (Ge)	dissolution	11.3 ±0.4 mg/L	3%
	absolute Ge release	56.6 ± 2.0 mg/g	3%
	% of total availableGeeluted	5.83%
	Ge release/surface	47.6 mg/m²

x_avg= average of 3 test vessels (blank corrected, if the blank value is > reporting limit, otherwise blank assumed as 0).

s_between= standard deviation.

CV = Coefficient of Variation (%).

Applicant's summary and conclusion

Conclusions:

The dissolution in gastric fluid is used to estimate bioavailability after oral exposure. Bio-elution test according to state-of-the-art procedures, useful for determining dissolution capacity of In in gastric fluid.
Interpretation of results: low bioaccessibility of Ge from germanium

Executive summary:

During this study on Germanium at a loading of 0.2 g/L in simulated gastric fluid (pH 1.2), it was shown that a significant amount of germanium (average dissolved germanium concentration of 11.3 ± 0.4 mg/L

Ge or 56.6 mg/g Ge with a between-vessel variation of 3% (CV=3%)) was measured after 2 hours of extraction. Based on the specific surface area of germanium (i.e. 1.19 m²/g test item ) a germanium release per surface of 47.6 mg/m² was calculated. Based on the germanium content in the test item ( 97.2%) and the average dissolved germanium concentration, a germanium release of 5.83% could be calculated