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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The results of the original study have been reviewed, and it has been determined that the EC50 values are > 100 mg/L.  As such, the classification of R52/R53  proposed in the original notification under the Seventh Amendment is no longer applicable.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

It should be noted that under the current REACH regulation for which this registration is being made, there have been some alterations to the manner in which Algal data is interpreted. It is known that the following is applicable:


1. In algal studies, the result based on growth rate shall be used for evaluation instead of those for biomass. Thus, the result of the algae study is ErC50 >87 mg/L (measured). However there is no reason to recalculate nominal concentrations with measured concentrations as long as the result of the analytical monitoring is >80% of the nominal concentration. For this reason, the actual result which should be reported within this registration under REACH should be ErC50 >100 mg/L (nominal).

2. The decrease of  growth rate at the highest concentration (87/100 mg/L) was given as 23%. A further examination of the probit analysis has been undertaken by an independent consultant whom has extrapolated the original values with ToxRat (version 2.10.05), Weibull distribution.


The results of this assessment are as follows:

Based on nominal concentrations: ErC50 = 175 mg/L (95%CV: lower 145 mg/L, higher 253 mg/L).
Based on measured concentrations: ErC50 = 152 mg/L (95%CV: lower 125 mg/L, higher 221 mg/L).


As such it is proposed that the current classification R52/R53, on the basis of the original algal results is no longer applicable. The classification detailed in Section 2 of this registration dossier indicate this required revision.