Germanium

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

43.4 µg/L

Assessment factor:

1

Extrapolation method:

sensitivity distribution

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

43.4 µg/L

Assessment factor:

1

Extrapolation method:

sensitivity distribution

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

7 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

599.4 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

19.6 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

43.4 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Conclusion on classification

Ecotoxicity tests were performed with GeO2 as test substance. From the data, the ecotoxicity reference values (ERV's) for acute and chronic toxicity of GeO2 and of the Ge-ion in general, were derived.

To check the capacity of Ge metal powder to generate Ge-ions in solution, Transformation/Dissolution (TD) testing was also performed according to OECD 29 at pH 8, where the highest TD was observed.

 

acute effect:

The lowest EC50 value of 0.206mg GeO2 /L was observed on the freshwater diatomea Navicula pelliculosa, in a standard OECD 201 algae test (Fraunhofer 2018). From this result, a general EC50-based ERV of 0.143mg Ge/L can be derived for the Ge-ion.

 

The acute TD test showed that after 7days, 1mg/l loading of Ge-powder results in 0.0615 mg/L Ge in solution. The ERV is thus not exceeded at 1 mg/L loading of the substance. Therefore, Ge metal powder is not classified for acute aquatic effect under CLP.

 

chronic effect:

the lowest EC10 value of 0.1003 mg GeO2/L was also observed on the freshwater diatomea Navicula pelliculosa, in a standard OECD 201 algae test (Fraunhofer 2018). From this result, a general EC10-based ERV of 0.07mg Ge/L can be derived for the Ge-ion.

 

The chronic TD test showed that after 28 days, 1 mg/L loading of Ge powder results in 0.17mg/L Ge in solution. The chronic ERV of 0.07mg Ge/L is thus exceeded at this loading. It is however not exceeded at 0.1mg/L loading of the substance. From the results, it follows that 0.07 * 1000/170 = 0.41mg Ge powder would be needed for reaching the chronic reference value for the Ge-ion.

 

To define the level of the chronic classification, it must be established whether or not the substance should be considered to be rapidly degradable or not. "Degradability" is a concept related to organic substances and as such not applicable to inorganic substances. Degradability is considered in the context of chronic aquatic classification to assess the potential of the substance to remain present in the water column, and, as such to be able to excert a chronic effect. In this spirit, the concept of "removal from the water column" has been developed for metal substances: the time and degree of metal presence in the water column (and related potential for chronic toxicity) is measured over a given period similar to the one applied to the organic substances. The same criterion for removal is applied. The results on GeO2 demonstrate that Ge removal from the water column is 80% after 4 weeks. It was also demonstrated experimentally that resuspension of the sediment does not result in remobilisation of Ge into the water column. Based on these results, it is concluded that Ge and its salts are to be considered as equivalent to rapidly degradable.

 

Given that a) the ERV of 70 µg Ge/L is exceeded at 1mg/L loading, but not at 0.1mg/L loading of the substance, and b) that Ge powder should be considered as equivalent to rapidly degradable, Ge-powder is classified as chronic 3 for aquatic effect.