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Ecotoxicological information

Endpoint summary

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To evaluate the aquatic toxicity of the test substance several studies on fish, aquatic invertebrates and algae and cyanobacteria were performed. The following results are based on the worst case endpoint of each taxonomic group.

Short-term toxicity to fish

The short term toxicity of the test substance to fish was tested in freshwater and in marine water studies. In a 96 -hour static acute toxicity freshwater study with the test substance (free acid of Diflufenzopyr sodium salt) with rainbow trout (Oncorhynchus mykiss) the LC50 value was 106 mg a.i./L. The 96 -hour no observed effect concentration, determined by a visual examination of the mortality data, was 80 mg a.i./L

In a marine water key static study, the 96-hour LC50 value for sheepshead minnows exposed to the test substance (free acid of Diflufenzopyr sodium salt) was > 138 mg a.i./L, the highest concentration tested. The 96-hour no mortality concentration and NOEC were 138 mg a.i./L.

Long term toxicity to fish

In a 21-d long term toxicity study to fathead minnows (Pimephalespromelas) under static-renewal conditions with the test substance (Diflufenzopyr sodium salt), the LOEC for the study, based on dry weight, was 10 mg a.i./L. and the NOEC was 5.0 mg a.i./L.

Short-term toxicity to aquatic invertebrates

The acute toxicity of the test substance (free acid of Diflufenzopyr sodium salt) was tested in a 48 -hour short term toxicity study to aquatic invertebrates. The 48h-EC50 value for the Daphnia magna exposed was >130 a.i. mg/L.

Long-term toxicity to aquatic invertebrates

In a 21 -d long term toxicity study to aquatic invertebrates of the test substance, the daphnia magna exposed to 15 mg a.i./L had statistically reduced survival. In this study, the most sensitive endpoints were reproduction and growth. The NOEC for reproduction was considered to be 1.9 mg a.i./L. The LOEC for reproduction is 3.8 mg a.i./L. The LOEC and the NOEC for growth were determined to be 3.8 mg a.i./L and 1.9 mg a.i./L, respectively.

Toxicity to algae and cyanobacteria

The toxicity of the test substance to algae and cyanobacteria was tested in a freshwater and in marine algae. In a key study of freshwater diatom, the 5-day EC50 was calculated to be 0.10 mg A.E.(acid equivalent)/L (95% confidence limits of 0.033 and 0.36 mg A.E.(acid equivalent)/L.

The 5-day No-Observed-Effect Concentration (NOEC) was determined to be 0.0030 mg A.E.(acid equivalentt)/L.

In a key study of marine water diatom, the effects of the test substance observed on the growth of Skeletonema costatum were clearly concentration related and yielded a 5-day EC50 value, based on cell density, of 0.14 mg A.E. (acid equivalent)/L. The 5-day No-Observed-Effect Concentration (NOEC) was determined to be 0.0064 mg A.E.(acid equivalent)/L

Toxicity to aquatic plants other than algae

Based on mean measured concentrations of the test substance (diflufenzopyr sodium salt), the 14-day EC50 for frond density was estimated to be >0.35 mg A.E.(acid equivalent)/L. The 14 -day No-Observed-Effect Concentration (NOEC) for frond density was determined to be 0.0039 mg A.E.(acid equivalent)/L. Based on mean measured concentrations, the 14-day EC50 based on frond biomass was estimated to be >0.35 mg A.E. (acid equivalent)/L, the highest concentration tested. The No-Observed-Effect Concentration (NOEC) for frond biomass was determined to be 0.35 mg A.E.(acid equivalent)/L.