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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

All test results for 7 days.  EC50 values:
Lemna gibba: #plants: 4432; #fronds: 4816; biomass: 5967mg/l
Lemna minor (all biomass end points only, clones shown): 6591: 4880mg/l, 7101: 5771mg/l; 7102: 18308mg/l; 7136: 10789mg/l
All test results for 7 days. NOEC values:
Lemna gibba: #plants and #fronds: 280mg/l; biomass: 1296mg/l
Lemna minor (all biomass end points only, clones shown): 6591: 778mg/l, 7101: 467mg/l; 7102: 1296mg/l; 7136: 6000mg/l

Key value for chemical safety assessment

EC50 for freshwater plants:
4 432 mg/L
EC10 or NOEC for freshwater plants:
280 mg/L

Additional information

In a well reported study that was carried out to guideline, five species of duckweed (Lemna gibba and 4 clones of Lemna minor, 6591, 7010, 7102 and 7136) were exposed to ethanol over a concentration range of 1 to 21000mg/l over a 7 day period. The measures of growth inhibition used to assess toxicity were number of plants, number of fronds and total dry biomass at the end of the study compared to controls. The measures of number of plants in particular but also the number of fronds to a lesser extent proved highly variable with some species, as shown by the very large confidence intervals.  The lowest results were obtained with Lemna gibba, which also showed lower variability in the values, and is therefore used as the key study.