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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The ptBP was found to be moderately toxic to aquatic algae with a 72h-ErC50 value of 14 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
14 mg/L
EC10 or NOEC for freshwater algae:
0.32 mg/L

Additional information

The growth inhibition effect of ptBP on Selenastrum capriconutum was assessed over a period of 72 hours, and the study was conducted in compliance with the OECD Guidelines for the Testing of Chemicals No. 201, and in accordance with the Principles of GLP (NIVA, 2001). The test was conducted with eight nominal concentrations of the test material (0.32, 0.56, 1.0, 1.8, 3.2, 5.6, 10 and 18 mg/L), with three replicates, and under static conditions. Significant effects on the growth rate were observed above 0.32 mg/L (72 h NOEC), and the 72h ErC50 was 14 mg/L. Growth inhibition was not complete at 18 mg/L, which was the highest concentration tested.

In a similar 72h algae toxicity study, performed according to the OECD Guidelines for the Testing of Chemicals No. 201, and conducted under static conditions, five different concentrations of ptBP (9.53, 17.2, 30.9, 55.6, and 100 mg/L) were used (Hüls AG, 1985, cited in the EU Risk Assessment). The test concentrations were analytically monitored, and a solubilizer was used to increase the solubility of the test material. Biomass inhibition was used as an endpoint with a 72h EC50 value of 22.7 mg/L, based on nominal concentrations. The NOEC and LOEC were identified as 9.53 mg/L and 17.2 mg/L, respectively.