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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The toxicity of Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked  to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201. The aim of the study was the determination of NOEC, LOEC, EC10 - , EC20- and EC50 - values of growth rate and yield over a period of 72 hours. 
The study was conducted under static conditions with a saturated solution* (i.e. 100 %) and further four dilution levels of 9.96 - 17.7 - 31.6 - 56.2 % of the saturated solution, corresponding to geometric mean measured test item concentrations of 226 - 399 – 638 – 1268 – 2088 µg/L.
The concentrations of the test item were analytically verified by LC-MS/MS analysis at test start and test end of all dilution levels and the control. The measured concentrations at test start were in the range of 180 – 2154 µg/L. The measured concentrations at the end of the test were in the range of 283 – 2024 µg/L. All effect values given are based on the geometric mean measured concentrations of the test item.

Key value for chemical safety assessment

EC50 for freshwater algae:
2 088 µg/L
EC10 or NOEC for freshwater algae:
2 088 µg/L

Additional information

In this study the test item was not found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata significantly, when tested with the saturated solution and further dilution levels. The effect values after 72 hours (geometric mean measured test item concentrations) were: The EC50-values with 95 % confidence intervals for inhibition of specific growth rate (ErC50) and yield (EyC50) after 72 hours were > 2088 µg/L for both endpoints. The NOEC-values for inhibition of specific growth rate and yield after 72 hours were 2088 µg/L (highest test concentration) for both endpoints.