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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

Effects on frond number: ErC50 (7 d) > 482 mg/l (Probit regression model)

Effects on dry weight: ErC50 (7 d) > 482 mg/l (Probit regression model)

Key value for chemical safety assessment

EC10 or NOEC for freshwater plants:
5.47 mg/L

Additional information

No data on target substance was available, thus acute toxicity to aquatic invertebrates was assessed using data on Similar Substance 02. Details on the read across are attached in section 13.

The substance was tested for toxicity on freshwater aquatic plants, i.e. Lemna minor, according to OECD guideline 221 under static exposure conditions.

Initial measured concentrations were 31.5, 59.3, 125, 245 and 490 mg/l of active ingredient. Concentrations at day 7 in % of initial value showed a decrease at the lower concentrations, possibly due to some adsorption to the roots. The significant decrease at low concentrations suggests that roots can only adsorb a small quantity of test item, thus “adsorption” effect is only visible in solution where less material is present; on the contrary, the small loss on the highest concentration is not be measurable.

In order to account for the decrease of test concentrations, geometric means over 7 days of measured concentrations were used in the assessment.

Plants at concentrations up to 125 mg/l were similar to control, in terms of number of fronds and length of roots. At 250 and 500 mg/l, there was a dose-dependent decrease in the size and number of fronds and in the length of roots.

Effects concentrations (EC10 and EC50), based on growth rate and yield, were determined using Probit regression model.

No observed effect concentrations (NOEC) were estimated by Williams multiple sequential t-test.

The EC50 values after 7 days resulted to be:

- > 482 mg/l of active ingredient, referred to the growth rate of frond number,

- > 482 mg/l of active ingredient, referred to the growth rate of dry weight.

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