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Toxicity to aquatic algae and cyanobacteria

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Description of key information

The acute toxcity of benzyldimethylamine to Algae (Desmodesmus subspicatus) was tested according to EU method C.3 'Alga Inhibition Test' (2009) yielding an ErC50(72 h) of 1.34 mg/L and NOEC(72 h) of 0.24 mg/L (Currenta, 2010).

Key value for chemical safety assessment

EC50 for freshwater algae:
1.34 mg/L
EC10 or NOEC for freshwater algae:
0.24 mg/L

Additional information

A study was performed to assess the adverse effects of benzyldimethylamine on the growth rate (= rate of increase in cell density with time) and the yield (= biomass at time t minus initial biomass) of the planktonic freshwater algal species Desmodesmus subspicatus (former name: Scenedesmus subspicatus) over several generations. The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3 ‘Freshwater Alga and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006). Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 0.032, 0.1, 0.32, 1.0, 3.2, 10, 32 and 100 mg/L of benzyldimethylamine dissolved in dilution water. Auxiliary used to prepare the test media was a magnetic stirrer. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were also used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration. The following values were determined:

ErC 50* (0-72 h) = 1.34 mg/L

ErC 10* (0-72 h) = 0.24 mg/L

NOEC [r]* (ta 0.05) = 0.24 mg/L#

# The software tool ToxRatPro Version 2.10 was not able to calculate a NOEC [r], due to insufficient variability among the counts in a Microcell counter. In agreement with existing regulatory practice, the ErC10 was used to calculate the NOEC [r].

* Reduction of growth rate (ErCx, NOEC [r]) is the preferred endpoint according to OECD 201 and for regulatory purposes in the EU. Results relating to yield (EyCx, NOEC [y]) were calculated to fulfil regulatory requirements in some countries (but not in the EU) and are given in the results section of this report.

The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 71.3-100.0% of nominal values at 0 hours, and from 67.2-83.6% of nominal values at 72 hours, respectively.