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EC number: 457-320-2 | CAS number: -
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
Description of key information
In an algal growth inhibition study of EC# 434-650-5, the 72-hour NOELR based on cell number was 4.05 mg/litre (nominal loading rate).
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 9.62 mg/L
- EC10 or NOEC for freshwater algae:
- 4.05 mg/L
Additional information
No toxicity to aquatic algae and cyanobacteria studies are available for EC# 457-320-2; however, one study is available for the structurally and chemically similar substance EC# 434-650-5: a 72-hour algal growth inhibiton study conducted to GLP and in accordance with OECD Test Guideline 201. Due to the poor solubility of the test material (which was 87% pure EC# 434-650-5) in solvents that would not affect algal growth, test waters were prepared as Water Accomodated Fractions (WAFs) of nominal loading rates of active ingredient (i.e. EC# 434-650-5). WAFs were sampled and analysed for molybdenum (Mo) content, and the concentrations of EC# 434-650-5 calculated.
Nominal loading rates were 0, 4.05, 8.89, 19.7, 43.1 and 94.6 mg a.i./litre. Based on the measured levels of Mo at 0 and 72 h (0.0124, 0.0451, 0.0547, 0.127 and 0.517 mg Mo/litre), the actual concentrations of active ingredient were calculated to be 0.135, 0.492, 0.597, 1.38 and 5.64 mg/litre; however, since the Mo content of the water-soluble portion of the test material is not known, these values should be treated with caution.
The test material caused a concentration-related inhibition of algal growth. The no-observed-effect loading rate was 4.05 mg a.i./litre, based on cell number, and the EbL50 and EtL50 were 9.62 and 14.0 mg a.i./litre, respectively, based on area under the growth curve and average specific growth rate.
In view of the structural and chemical similarities, it is considered that the results of this study can be used for read-across to EC# 457-320-2.
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