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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

96 hr EC50 (biomass) in algae (Selenastrum capricornutum): 3.68 mg/L
96 hr EC50 (growth rate) in algae (Selenastrum capricornutum): 8.93 mg/L. NOEC<1.2mg/l
72 hr EC50 (biomass) in algae (Selenastrum capricornutum): 2.61mg/l. NOEC=0.852mg/l
QSAR prediction: EC50=2.3; ChV=0.87.

Key value for chemical safety assessment

EC50 for freshwater algae:
8.93 mg/L
EC10 or NOEC for freshwater algae:
0.852 mg/L

Additional information

In a guideline (OECD 201) and GLP study, LISEC reported the following toxicity results for ENB in the algae Selenastrum capricornutum.

96 hr EC50 (biomass): 3.68 mg/L

96 hr EC50 (growth rate) : 8.93 mg/L

96 hr NOEC <1.2 mg/L

In a guideline (OECD 201) and GLP study, the Environment Agency of Japan (1999) reported the following toxicity values for ENB in algae (Selenastrum capricornutum).

72 hr EbC50 = 2.61 mg/L

NOEC = 0.852 mg/L

The end point specific guidance on REACH (Guidance on information requirements and Chemical Safety Assessment, Chapter R7B) advises that EC50 values based on biomass should not be used. Therefore the only available EC50 based on growth rate is used as the key parameter. However, this study did not identify a true NOEC. A true NOEC was derived in the second study (lower than the LOEC from the first one). Since the issue of biomass versus growth rate is not significant for a NOEC, this value is used for the key parameter for this end point.