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Toxicity to aquatic algae and cyanobacteria

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Description of key information

OECD 201, GLP and Klimisch 1 algal inhibition 72 hour ErC50 4.11 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
4.11 mg/L
EC10 or NOEC for freshwater algae:
1.25 mg/L

Additional information

The toxicity of DimerFA_PEPA_PAA (Batch no.: BB 001694 V1) to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD Guideline for Testing 201 (2006) atDr.U.Noack-Laboratorien,31157 Sarstedt, Germany.The aim of the study was to assess the effects on the growth rate in a medium containing 50% natural river water and 50% algal culture medium over a period of 72 hours. 


The study was conducted under static conditions with an initial cell density of 5089 cells/mL.Five concentration levels were tested in a geometrical series with a dilution factor of 2.00 (nominal):0.625 - 1.25 - 2.50 - 5.00 - 10.0 mg/L. Three replicates were tested for each concentration level and six replicates for the control. Environmental conditions (pH and room temperature) were determined to be within the acceptable limits.

DimerFA_PEPA_PAA has low water solubility and may sorb to organic and inorganic materials by different mechanisms. Due to these properties the test item was difficult to test in artificial water (e.g. sorption to the test organism and walls of the test vessel). Natural river water contains particulate as well as dissolved organic carbon to which the test item can sorb partially preventing that the test item settles onto surfaces. The sorbed fraction of the test item was difficult to extract from the test system which normally leads to low analytical recoveries. Nevertheless the test item was present in the test system and therefore available for exposure (dissolved in water and sorbed).


No determinations of the test item concentrations were carried out. Preliminary investigations including the use of different analytical techniques have shown that no specific method was available that met the required sensitivity in the range of the test concentrations.


All effect levels are given based on nominal concentrations of DimerFA_PEPA_PAA.

The 72 h ErC50 of DimerFA_PEPA_PAA to the freshwater green algaPseudokirchneriella subcapitatawas 4.11 mg/L (95% confidence limits of 3.62 – 4.55 mg/L) and the corresponding NOEC was 1.25 mg/L.