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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Link to relevant study record(s)

Description of key information

In the key study, the toxicity of alpha-methylstyrene to Desmodesmus subspicatus CHODAT was investigated according to OECD Guideline 201 (Alga, Growth Inhibition Test; 2006) and EU Method C.3 (Algal Inhibition Test; 2008) under static conditions. The test substance concentrations were determined by GC/FID. The 72 h NOEC, LOEC and EC50 based on growth rate were determined to be 2.26, 8.3, and 11.44 mg/L based on mean measured concentrations (geometric mean). 

Key value for chemical safety assessment

EC50 for freshwater algae:
11.44 mg/L
EC10 or NOEC for freshwater algae:
2.26 mg/L

Additional information

In total, there are 4 study results available to cover this endpoint. However only the most recent one (P&D REACH Consortium, 2010) is considered appropriate for risk assessment purposes. The other studies have been evaluated to be non-reliable based on the described test conditions/results or based on the fact that the validity criteria set forward in the OECD Guideline 201 (K3) were not met. Details on the non-suitability of these studies is provided in the respective RSS.

The toxicity of alpha-methylstyrene to Desmodesmus subspicatus CHODAT was investigated in a study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test; 2006) and EU Method C.3 (Algal Inhibition Test; 2008) under static conditions. In the main test, the algal cultures were exposed to nominal concentrations of 0 (control), 10, 20, 40, 80, and 100 mg/L corresponding to mean measured concentrations of 0 (control), 2.26, 8.30, 10.72, 26.56, and 32.39 mg/L (geometric mean of t=0 h) for 72 h. The test substance concentrations were determined by GC/FID. The recoveries of the test substance concentrations after 72 h were < 80% of those determined at time 0, and the measured concentrations deviated more than 20% from the nominal values. Based on these findings, the reported effect concentrations refer to mean measured concentrations (geometric mean). The 72 h NOEC, LOEC and EC50 based on growth rate were determined to be 2.26, 8.3, and 11.44 mg/L based on mean measured concentrations (geometric mean). The 72 h NOEC, LOEC and EC50 based on yield were determined to be <2.26, <=2.26, and 4.347 mg/L based on mean measured concentrations (geometric mean). The validity criteria of the guideline were fulfilled.