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Toxicity to aquatic algae and cyanobacteria

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Description of key information

Based on the results of this study, the 72-hour and 96-hour EC50(algae) of ITC 288/S, based on biomass and on growth rate, was found to be > 100 mg/L. The  72-hour and 96-hour NOEC values, based on biomass and on growth rate, was found to be >= 100 mg/L.

Therefore, ITC 288/S should not be considered as harmful to the aquatic organisms tested.

Key value for chemical safety assessment

Additional information

One study to assess the effect of the test material ITC 288/S to the growth of Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) is available. The method followed that described in the OECD Guidelines for Testing of Chemicals (1984) No. 201 and the US EPA Code of Federal Regulations Title 40, Part 797, Section 1050. The test was performed according to the GLP.

The test species were cultured under continuous illumination on an orbital shaker at 24°C for 96 hours, and were exposed to the test material at a nominal concentration of 100 mg/L under static test conditions. Growth was recorded after 24, 48, 72 and 96 hours by spectrophotometry. By comparison with control, the test substance showed no inhibition of the growth rate nor the biomass. Therefore, the effect concentrations were determined as follows:

72 -hr EbC50 > 100 mg/L

96 -hr EbC50 > 100 mg/L

72 -hr ErC50 > 100 mg/L

96 -hr ErC50 > 100 mg/L

72 -hr NOEC >= 100 mg/L based on biomass and growth rate

96 -hr NOEC >= 100 mg/L based on biomass and growth rate

Verification of test concentration showed that the concentrations were within the desired limits (i.e. >= 80% of nominal values) and therefore, the nominal test concentrations were used for the estimation of EC50 values.

The study has been performed in 1992. At that time, only one validity criteria was reported in the OECD TG 201, which requested that the cell density in the control cultures should have increased by a factor of at least 16 within three days. This validity criteria has been fulfilled as the biomass in the control cultures has increased by a factor of 99 and 180 within the 72-hour and 96-hour test periods respectively.

There is a lack of raw data to check the two additional validity criteria reported in the OECD TG 201 published in 2006. Therefore, this study is considered as reliable with restriction.