Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Hazard for aquatic organisms


Hazard assessment conclusion:
no hazard identified

Marine water

Hazard assessment conclusion:
no hazard identified


Hazard assessment conclusion:
PNEC value:
200 mg/L
Assessment factor:
Extrapolation method:
assessment factor

Sediment (freshwater)

Hazard assessment conclusion:
no hazard identified

Sediment (marine water)

Hazard assessment conclusion:
no hazard identified

Hazard for air


Hazard assessment conclusion:
no hazard identified

Hazard for terrestrial organisms


Hazard assessment conclusion:
no hazard identified

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
no potential for bioaccumulation

Additional information

Conclusion on classification

The water solubility of ditantalum pentaoxide determined according to OECD Guideline 105 is < 5 µg/L at 10 °C and 20 °C (Wenighöfer & Fröschl, 2012). In addition, it is demonstrated by the results of the T/D Test according to OECD 29 that the substance is virtually insoluble. The highest dissolved Ta concentration in the test medium was 0.16 µg/L (loading 100 mg/L after 7 days, samples 0.2 µm filtered and centrifugally ultra-filtered (3 kDa filtration)).
The available key studies addressing three different aquatic species (daphnia, algae and fish) were conducted with nominal test substance concentrations of 1 mg/L. Actual (dissolved) test substance concentrations were not analytically verified. However, due to the reported procedures for the preparation of test solutions, the test substance is considered to have been tested at its maximum solubility in the respective test media. The following results based on the nominal test substance concentration were obtained: 

- Short term toxicity to fish (Brachydanio rerio): 96 hour LC0 1 mg/L (limit of solubility) (Caspers, 2001).
- Short-term toxicity testing to invertebrates (Daphnia magna): 48 hour EC0 1 mg/L (limit of solubility). (Müller, 2001)
- Growth inhibition study on aquatic plants (Desmodesmus subspicatus): no toxic effects were observed at 1 mg/L (limit of solubility). (Casper, 2000)

The assessment of ready biodegradability is not applicable to inorganic substances.

Based on the high insolubility of the substance in water and its high molecular weight, it is not expected to bioaccumulate.

With respect to the information available for this substance (presented above), the substance is not classified as hazardous to the aquatic environment (short or long-term) in accordance with Regulation (EC) 1272/2008.