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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Aquatic algae studies were found for analog and structurally similar substances and were performed according to EPA OTS 797.1050 or OECD TG 201.  In each of these studies, the 96 hour Effective Loading Rate was equivalent to the highest concentrations tested.  

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

Aquatic algae studies were found for analog and structurally similar substances and were performed according to EPA OTS 797.1050 or OECD TG 201. In each of these studies, the 96 hour Effective Loading Rate was equivalent to the highest concentrations tested. A series of 96-hour acute toxicity algal studies were performed on several substances using cultures of Selenastrum capricornutum (now Pseudokirchneriella subcapitata) (Ward, 1994). The first algal exposure was to test substance CASN 115733-09-0 at nominal concentrations of 100, 300 and 1000 mg/L as WAF loadings under static conditions in accordance with the EPA OTS 797.1050.  Daily cell counts were made visually by means of direct microscopic examination with a hemocytometer. At 72-hours cell density measurements in the treatments were 80%, 62% and 70% of the control at 100, 300 and 1000 mg/L, respectively. At 96-hours cell density measurements in the treatments were 70%, 66% and 88% of the control at 100, 300 and 1000 mg/L, respectively. At 72-hours, specific growth rate measurements were 95%, 90% and 92% of the control at 100, 300 and 1000 mg/L WAF, respectively. At 96-hours, specific growth rate measurements were 93%, 92% and 97% of the control at 100, 300 and 1000 mg/L WAF, respectively. The 72-hour and 96-hour Effective Loading Rate (EL50) was >1000 mg/L nominal WAF. The 72-hour and 96-hour No Observed Effect Levels (NOEL) was 1000 mg/L nominal WAF based on both specific growth rate and cell density.

The next substance tested in the same study was CAS 71486-79-8 (Ward, 1994). Nominal concentrations of 100, 300 and 1000 mg/L as WAF loadings under static conditions were performed on green algae in accordance with the EPA OTS 797.1050. At 72-hours cell density measurements in the treatments were 133%, 75% and 64% of the control at 100, 300 and 1000 mg/L, respectively. At 96-hours cell density measurements in the treatments were 93%, 77% and 52% of the control at 100, 300 and 1000 mg/L, respectively. At 72-hours, specific growth rate measurements were 108%, 92% and 88% of the control at 100, 300 and 1000 mg/L WAF, respectively. At 96-hours, specific growth rate measurements were 98%, 95% and 86% of the control at 100, 300 and 1000 mg/L WAF, respectively. The 72-hour and 96-hour Effective Loading Rate (EL50) was >1000 mg/L and the 72-hour and 96-hour No Observed Effect Concentrations (NOEL) was 1000 mg/L based on both specific growth rate and cell density.

The final substance used in the study by Ward (1994) was CASN 71486-47-5. Green algae were dosed at nominal concentrations of 125, 250, 500, 1000 and 1500 mg/L as WAF loadings under static conditions in accordance with the EPA OTS 797.1050. At 72-hours cell density measurements in the treatments were 97%, 100%, 101%, 95% and 25% of the control at 125, 250, 500, 1000 and 1500 mg/L respectively. At 96-hours cell density measurements in the treatments were 78%, 61%, 62%, 58% and 31% of the control at 125, 250, 500, 1000 and 1500 mg/L respectively. At 72-hours, specific growth rate measurements were 100%, 100%, 100%, 98% and 75% of the control at 125, 250, 500, 1000 and 1500 mg/L WAF, respectively. At 96-hours, specific growth rate measurements were 95%, 91%, 91%, 89% and 72% of the control at 125, 250, 500, 1000 and 1500 mg/L WAF, respectively. The 72-hour Effective Loading Rate (EL50) was 1400 mg/L and >1500 mg/L based on cell density and specific growth rate, respectively. The 96-hour Effective Loading Rate (EL50) = 1100 mg/L and >1500 mg/L based on cell density and specific growth rate, respectively. The 72-hour and 96-hour No Observed Effect Loading Rates (NOEL) were 1000 mg/l based on both specific growth rate and cell density.

In a 72 hour toxicity study, the cultures of the green algae (Scenedesmus subspicatus) were exposed to sulphonic acids, petroleum, calcium salts at nominal concentrations of 0 and 100 mg/L nominal WAF loading rate under static in accordance with the guideline OECD Guideline 201 (Alga, Growth Inhibition Test) (Mead, 2005). The 72 hour EC50 based on biomass was >100 mg/L WAF loading rate and the EC50 based on specific growth rate was >100 mg/L WAF loading rate. There was no compound related phytotoxic effects. The 72-hour NOEL (biomass and specific growth rate) was 100 mg/L WAF loading rate.