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Toxicity to aquatic algae and cyanobacteria

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Description of key information

The 72 hour EC50 value of 2-amino-6-chloro-4-nitrophenol to Selenastrum capricornutum for biomass and growth rate were 8.60 and 82.4 mg/L, respectively, based on nominal concentrations. Since the validity criteria for the growth rate are met, the 72h-ErC50 = 82.4 mg/L is considered as the most reliable value to express the adverse effect of 2-amino-6-chloro-4-nitrophenol to Selenastrum capricornutum..

Key value for chemical safety assessment

EC50 for freshwater algae:
82.4 mg/L

Additional information

The toxicity of 2 -amino-6 -chloro-4 -nitrophenol toSelenastrum capricornutumwas determined in a 72 hours algae growth inhibition test, following the OECD 201 guideline and GLP. 

Based on the results of a range finding test, the definitive test was conducted under static conditions at the following nominal test concentrations:0 (control), 8.54, 18.8, 41.3, 90.9 and 200 mg/L. An additional test on200 mg/L was conductedasslight toxic effects were induced by the colour of the test substance. The test substance concentration was maintained over 80 -120% of the nominal throughout the duration of the exposure period (control done on the 200 mg/L test concentration) . So the resulst are expressed as nominal concentrations. 3 replicates were tested for each test concentration and control.Endpoints evaluated were EC50of biomass and growth rate over a period of 72 hours.

Some discrepancies were noted compared to the guideline concerning the range of temperatures which is outside the required temperatures in the method, the composition of the test medium (the applied concentration of some elements deviate from those mentionned in the Gorham's medium),the tested concentrations checking since only the highest tested concentration was analysed.Nevertheless all the validity criteria are fullfilled and therefore this study is considered as Klimisch 2.

Under the conditions of this test, the 72 hour EC50 value of2 -amino-6 -chloro-4 -nitrophenoltoSelenastrum capricornutumfor biomass and growth rate were 8.60 and 82.4 mg/L, respectively, based on nominal concentrations.No NOEC can be provided since at the lowest tested concentrations more than 25% inhibition is observed. Since the validity criteria for the growth rate are met, the 72h-ErC50 = 82.4 mg/L is considered as the most reliable value to express the adverse effect of 2-amino-6-chloro-4-nitrophenol to Selenastrum capricornutum.

This toxicity test is classified as acceptable unless reported discrepancies with the requirements of the OECD Guideline 201.