Neodymium trifluoride

Toxicity to aquatic algae and cyanobacteria

Description of key information

The 72 hour LOELR of the read across substance neodymium oxide was 48 mg/L, the NOELR was 22 mg/L and the EL50 was >100 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

22 mg/L

Additional information

The key study was conducted on the read across substance neodymium oxide in line with GLP and the standardised guidelines OECD 201 and EU Method C.3. It was assigned a reliability score of 2 in accordance with the criteria detailed by Klimisch (1997).

In a 72 hour toxicity study, cultures of the green algal species Scenedesmus subspicatus were exposed to the test material at the loading rates of 4.8, 10, 22, 48 and 100 mg/L under static conditions.

The NOELR , the LOELR and EL50 values based on the growth rate were 22 mg/L, 48 mg/L and > 100 mg/L, respectively.   

Additional remarks:

In the test media, the phosphate concentrations in the saturated solution (loading rate 100 mg/L) and the dilution 1:2.1 (loading rate 48 mg/L) were statistically significantly reduced compared to the control (results of a Student-t test with Bonferroni correction; p<0.01) for up to 48 hours. The loss of phosphate can be explained by the formation of insoluble complexes of phosphate with the test material (which is a well-known behaviour of rare earth elements in the environment) during stirring of the dispersion. The depletion of phosphate in the test medium during the test might have been the reason for the inhibition of algal growth determined at these test concentrations. Thus, growth inhibition due to a secondary effect (i.e. the complexation of the essential algal nutrient phosphate by the test material) cannot be excluded.