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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

Description of key information

In a static growth-inhibition study, Pseudokirchneriella subcapitata was exposed to the test item for 72h according to OECD 201. Due to the decrease of test material below the limit of detection the effect concentrations are based on the initial measured concentrations as following: EC10 = 0.270 mg/L, EC20 = 0.360 mg/L, and EC50 = 0.626 mg/L. 

Key value for chemical safety assessment

Additional information

The growth-inhibition study of the test substance to the green algae Pseudokirchneriella subcapitata was assessed in a key study according to OECD Guideline for Testing of Chemicals No. 201. The toxicity evaluation of the test item for green algae was performed in a static test with 72h of exposure. The nominal concentrations were 0.025, 0.051, 0.128, 0.32, 0.8, and 2.0 mg/L (initial measured: 0.026, 0.047, 0.122, 0.311, 0.787, 2.064 mg/L). The effect concentrations after 72h based on the initial measured concentrations were EC10 = 0.270 mg/L, EC20 = 0.360 mg/L, and EC50 = 0.626 mg/L.

According to the OECD testing guideline (201) the alga growth inhibition test is a more dynamic test system than most other short-term aquatic toxicity tests. As a consequence, the actual exposure concentrations may be difficult to define, especially for adsorbing substances tested at low concentrations. In this case it is appropriate to base the analysis of the results on the initial measured concentrations. The present test substance decreased during the exposure time of 72h. Due to the test design a semi-static (as in the fish and Daphnia tests) or even flow through test design is not feasible, i.e. the test media cannot be replaced during the exposure time of 72h. The measured concentrations at test termination were below the limit of detection and the resulting mean measured concentrations artificially low. Therefore (in accordance with the OECD guideline no. 201) the original report was amended with the initital measured concentrations and the effects concentrations were based on these values.