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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

 ErC50 > 100 mg/L (95 % conf. limits - 114.6 – 1681.2)
EyC50 > 100 mg/L (95 % conf. limits - 48.5 – 280.4)

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L

Additional information

The effect the test item was assessed on algal growth using the unicellular green alga Pseudokirchneriella subcapitata (Selenastrum capricornutum), over an exposure period of 72 hours.


Five test concentrations in a geometric series (factor 3.2) and one untreated control were tested in the main experiment. The test design included three replicates at each test group and six replicates for the untreated control.


As the test item is a highly water soluble deep-coloured dye and the amount of light for photosynthesis is likely to be significantly affected by the shading effect of the coloured test solution, therefore a modified test was performed in order to separate physical effect of the coloured material from its true toxic effects.

Modified test results and results without modifying are reported separately (according to OECD TG No. 201).


The analysed concentrations deviated more than 20 percent from the nominal during the test therefore the biologically results are based on the measured geometric mean concentration.

The nominal concentrations used in the main experiment were: 1.0; 3.1; 9.8; 31.3 and 100 mg/L.The corresponding measured mean test item concentrations were: 0.5; 0.8; 2.9; 11.2 and 47.1 mg/L.


Statistical comparisons of average specific growth rates and yield in control and in treated groups were carried out using analysis of variance (ANOVA) and Bonferroni t-Test (a= 0.05) by TOXSTAT software.

The ErC50 and EyC50 values of the test item and their confidence limits were calculated using Probit analysis by TOXSTAT software.


The calculated endpoints were the following:


ErC50 > 100 mg/L (95 % conf. limits - 114.6 – 1681.2)

EyC50 > 100 mg/L (95 % conf. limits - 48.5 – 280.4)


The results of this experiment showed that the majority of the observed inhibition effect was related to the light absorption by the test item. However, a greater inhibition was seen at 72 hours when the Test Item was in contact with the algae cells. This indicates that there was also a slight toxic effecton the growth of the alga (Pseudokirchneriella subcapitata).


The substance is not considered harmful to algae on the basis of the results observed, and no classification is applicable.