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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

For assessing the aquatic risk for freshwater algae the lowest EC50 of 61.1 mg/L, based on cell number,  from the tests with standardised exposure time of 96 hours is used (St. Laurent et al. 1992).
For the saltwater species Entomoneis cf punctulata 3-day EC50 for growth rate of 76 mg/L was found in the study of Adams and Stauber (2004), based on measured concentrations, indicating comparable sensitivity of the marine and the freshwater algal species.

Key value for chemical safety assessment

EC50 for freshwater algae:
61.1 mg/L
EC50 for marine water algae:
76 mg/L

Additional information

Data were taken from phenol dossier - read across appreach was chosen because the content of phenol in the registered substance could be up to 50% (w/w).

Data on effects of phenol on algae is presented in EU-RAR (2006) in Section 3.2.1 (Aquatic compartment (incl. Sediment), page 36ff).

It is stated that the EC50 values of the different algal species are in the range from 7.5 – 370 mg/L and the lowest effect value (EC50 7 mg/L) was found by Beaubien et al. (1986) in a study conducted over 8 days with the green algae Pseudokirchneriella subcapitata. Bringmann & Kühn (1978) measured the same value as 8-day TTC (toxicity threshold concentration) for Scenedesmus quadricauda. As the TCC is defined as 3% effect compared to the control, this value can be considered as a NOEC. For the blue-green algae Microcystis aeruginosa a TTC of 4.6 mg/L was found by Bringmann & Kühn (1978). However, after 8 days the algae (esp. green algae) may not longer be in the exponential growth phase and this can have a negative influence on the test result. Therefore, these very low effect values should be used with care.

The lowest EC50 from a test with a standardised exposure time of 96 hours is 61.1 mg/L obtained in a test with Pseudokirchneriella subcapitata (St. Laurent et al., 1992).

 

For the freshwater green algae Pseudokirchneriella subcapitata andChlorella vulgaris three growth inhibition tests with a standard exposure time of 96 h are available. The EC50 values are 61.1 (cell number), 150 (growth rate), and 370 (growth rate) mg/L. For assessing the aquatic risk for freshwater algae the lowest EC50 of 61.1 mg/L, based on cell number, out of the tests with standardised exposure time of 96 hours is used (St. Laurent et al., 1992).

Though the test concentrations were not analytically verified, the phenol concentration is considered to be stable due to the finding in the studies from Colgan et al. (1982) and Lewis et al. (1983), where after a 2 day static exposure period the measured phenol concentrations were > 80 % of the nominal concentrations.

For the saltwater benthic diatom Entomoneis cf punctulata a 3-day EC50 of 76 mg/L was found in the study of Adams & Stauber (2004), based on measured concentrations. The EC50 is in the same order of magnitude as the growth rate EC50 values of the freshwater algae, indicating a possibly comparable sensitivity of the marine and the freshwater algal species.