Registration Dossier
Registration Dossier
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EC number: 221-259-8 | CAS number: 3048-64-4
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
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=2.21; ChV=1.12.
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
Analysis for the read across substance ENB:
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.
Justification for using read across substance ENB:
US EPA ECOSAR software (v1.00a) estimates the 96 -hr fish EC50 for VNB substance to be 2.38mg/l and the surrogate read across substance ENB to be 2.21 mg/L, based on structure activity relationship models for neutral organic compounds. Since the QSAR predicts the toxicity of ENB and VNB to be similar with the former the marginally more toxic, it seems both reasonable and conservative to select the key parameter from the measured data using the read across substance ENB.
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