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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The key study reported a 96-hour EC50 of >= 230 mg/L active substance based on Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) cell density (with a 95% CL of 47 to 1200 mg/L). 

Key value for chemical safety assessment

EC50 for freshwater algae:
230 mg/L
EC10 or NOEC for freshwater algae:
31 mg/L

Additional information

The key study is a reliable 1993 USEPA Guideline study (EPA OTS 797.1500 - Algal Toxicity). The freshwater Selenastrum sp. was exposed to a range of nominal concentrations of the test substance, sodium xylenesulphonate that reported a 96 -hour EC50 of >= 230 mg/L active substance based on cell density (with a 95% CL of 47 to 1200 mg/L). There was an apparent dose response and the 96-hour NOEC was 31 mg/L. The test substance was observed to be algistatic but not algicidal at the highest concentration tested (1000 mg/L active substance).

Two supporting studies were available. A 1994 EPA Guideline study (EPA OTS 797.1500) with the test substance calcium xylenesulphonate was conducted under GLP requirements and with analytical confirmation reported a 96 -hour EC50 of 758 mg/L active substance (with a 95% confidence limit of 592-924 mg/L) and a NOEC of 240 mg/L based on growth rate of Selenastrum sp. A 1995 EU Guideline study (EU C.3 Algal Inhibition Test) of sodium toluenesulphonate conducted under GLP requirements and with analytical confirmation reported a 72 -hour EbC50 of 150 mg/L active substance based on cell density and a 72 -hour ErC50 of 310 mg/L based on specific growth rate of Scenedesmus sp. The 72 -hour NOEC is 40 mg/L active substance based on biomass.