Registration Dossier

Administrative data

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
47.9 µg/L
Assessment factor:
1 000
Extrapolation method:
assessment factor

STP

Hazard assessment conclusion:
PNEC STP
PNEC value:
0.46 mg/L
Assessment factor:
10
Extrapolation method:
assessment factor

Hazard for air

Hazard for terrestrial organisms

Hazard for predators

Additional information

Gallium arsenide is usually produced by crystallisation in the form of a massive block, from which wafers (disks) are then produced. Only for experimental testing of intrinsic physico-chemical, toxicological and ecotoxicological properties, a GaAs powder sample has been prepared by the REACH registrant. This powder, which is not marketed, was produced by breaking/crushing and grinding of wafers and its particle size is characterised by the following parameters: D10 = 41.1 µm, D50 = 299.4 µm and D90 = 816 µm. This material has been used in a standard water solubility test (OECD 105), as well as in ecotoxicological tests (OECD 201,202,203).

Gallium arsenide is a metallic compound and as other metallic compounds practically not soluble in water. In an oxygen-free atmosphere a solubility of 13 µg GaAs/l (total As concentration) was observed. Under these conditions all dissolved As was found as As(III). Therefore one can assume that not GaAs itself was dissolved but the oxidized surface layer of the particles.

In the presence of oxygen and after a longer period of time, i.e. several days, higher solubilities seem to occur. These higher amounts of Galium and Arsenic in the medium are nearest a consequence of an oxidizing process.

Therefore, the standard concept of an equilibrium/saturation water solubility is not applicable to this substance.

Conclusion on classification

Ecotoxicity:

Ecotoxicity data are available from a powdered form only. The marketed massive form (wafers = disks (falling under the definition of articles under CLP- and REACH-regulation) is expected to have no water solubility. Therefore, the marketed massive form does not need to be classified and labelled. Tests have been performed with a powder form, which is not marketed (Particle size: D10=41.1, D50=299.4, D90=816.0 µm (total range: 4 – 2000 µm)). This does not represent the manufactured substance, which is a massive form. For powders a higher dissolution (or reaction) rate than for the massive form can be expected leading to a more stringent classification. Thus, the results are considered a worst case for powdered material.

Lowest EC50 (Daphnia magna, 48 h) = 47.9 % WAF of 100 mg/L GaAs in its powder form.

Short term toxicity tests with fish and algae revealed no effects up to 100% WAF of 100 mg/L GaAs in its powder form.

The classification shall be based on the smallest particle size marketed. For GaAs the powder form is not marketed. GaAs in its massive form is considered for classification.

There is no need for a classification of GaAs in its massive form as hazardous to the aquatic environment because no water solubility is expected for the massive form, the marketed wafers.

GaAs dust/ powder:

Dust/ Powder is classified as:

Hazard Category: Aquatic Chronic 3, Hazard statement: H412 (Harmful to aquatic life with long lasting effects) based on an EC50 (48 h, invertebrates) in between 10 and 100 mg/L according to table 4.1.0 b. iii of CLP-regulation (ammended by regulation (EC) 286/2011).

Bioaccumulation potential:

Bioaccumulation potential is not expected for GaAs or its free ions.

Degradation:

Even though the degradation criteria is not relevant for inorganic chemicals such as GaAs it cannot be neglected that oxydation leads to dissolved free metal ions, As-ions and Ga-ions which are available.

Conclusion:

Because there is no bioaccumulation potential the safety net classification does not apply.