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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

EC50 (7 d) = 110 µg a.i./L (Lemna gibba, growth rate, OPPTS 850.4400, mean measured)

NOEC (7 d) = 9.57 µg a.i./L (Lemna gibba, growth rate, OPPTS 850.4400, mean measured)

Key value for chemical safety assessment

EC50 for freshwater plants:
110 µg/L
EC10 or NOEC for freshwater plants:
9.57 µg/L

Additional information

One experimental study is available investigating the effects of the substance to aquatic plants (M-107686-01-1). The study was performed according to OPPTS 850.4400 (GLP) under static conditions using Lemna gibba as test organism.

The duckweed Lemna gibba G3 was exposed for 7 days to the nominal (mean measured) concentrations: control (<1.00), 4.69 (4.14), 9.38 (9.57), 18.75 (18.6), 37.5 (33.1), 75.0 (74.2) and 150 (152.5) µg a.i./L. Growth was determined by frond counts on days 0, 3, 5, and 7. Samples of the test item solutions, including controls, were taken on Day 0 (new solutions) and Day 7 (old solutions) to measure actual exposure concentrations.

The mean measured concentrations were 4.14, 9.57, 18.6, 33.1, 74.2, and 152.5 μg a.i./L for the 4.69, 9.38, 18.75, 37.5, 75.0, and 150 μg/L nominal concentrations, respectively. The measured concentrations were in the range of 88 to 102% of the nominal test concentrations. Observations revealed reduced frond size in the highest four treatment groups (18.6, 33.1, 74.2, and 152.5 µg a.i./L) as well as brown and transparent fronds in the highest three treatment groups (33.1, 74.2, and 152.5 µg a.i./L). The NOEC and LOEC in the 7-day exposure of Lemna gibba G3 to the test item were 9.57 and 18.6 µg a.i./L, respectively for the standing crop, growth rate and frond dry weight endpoints. Frond dry weight was the most sensitive endpoint. The NOEC and EC50 for this endpoint were 9.57 and 30.2 µg a.i./L, respectively. However, since growth rate is the preferred endpoint according to ECHA Guidance R.7b (ECHA, 2016) it was used as the key value (EC50 (7 d): 110 µg/L; NOEC (7 d): 9.57 µg/L). All endpoints were based on the mean measured concentrations.