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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Short term toxicity to Algae

Key value for chemical safety assessment

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

Additional information

Two studies are available for inspection as follows;

 

1) K1 study:

 

Selenastrum capricornutum were exposed to a 2500 µg/L accommodated fraction (WAF) loading rate of tricresyl phosphate (TCP) and evaluated for effects on cell density, area under the growth curve and growth rate. The 72 and 96-hour EL50, based on cell density, biomass and growth rate, was >2500 µg/L. The 72-hour NOAEL for cell density, biomass and growth rate was 2400, >2500 and >2500 µg/L, respectively, based on a calculated EL10 value. The 96 hour NOAEL, based on cell density, biomass and growth rate was 2500 µg/L.

 

2) K1 Study

 

Conducted on 'Reaction mass of bis(methylphenyl) phenyl phosphate and diphenyl tolyl phosphate and tris(methylphenyl) phosphate', Desmodesmus subspicatus was exposed for a period of 72 h to test solutions with concentrations, nominally 0.0122, 0.0243, 0.0486, 0.0972 and 0.194 mg/L. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were also used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration according to Williams Multiple Sequential t-Test Procedure. The following values were determined: ErC 50: 0.4042 mg/L and ErC 10: 0.016 mg/L. As analytical monitoring was carried out, the results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 65.5-69.1% of nominal values at 0 hours, and from 49.0-52.1% of nominal values at 72 hours, respectively. This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute algae study.

 

No toxicity at the limit of solubility in water was therefore noted in either study, and it is proposed that the substance does not cause algistatic effects at the limit of solubility.