Reaction mass of 3-(difluoromethyl)-1-methyl-N-[(1RS,4SR,9RS)-1,2,3,4-tetrahydro-9-isopropyl-1,4-methanonaphthalen-5-yl]pyrazole-4-carboxamide and of 3-(difluoromethyl)-1-methyl-N-[(1RS,4SR,9SR)-1,2,3,4-tetrahydro-9-isopropyl-1,4-methanonaphthalen-5-yl]pyrazole-4-carboxamide; isopyrazam

Toxicity to aquatic plants other than algae

Description of key information

Freshwater, 7-d EC50 > 500 μg/L and NOEC = 500 μg/L, Lemna gibba, OECD TG 221 and EPA 850.4400, Everett 2007

Additional information

One study is available for this endpoint. The toxicity of the test substance to the aquatic plant (Lemna gibba) was determined in a 7-day semi-static test. The study was performed according to OECD TG 221 and EPA 850.4400, and in compliance with GLP. The Lemna were exposed to nominal concentrations of 31.3, 62.5, 125, 250 and 500 μg/L, alongside a dilution water control and a solvent control (acetone). The initial frond number was 11 fronds (3 plants) per replicate. Assessments of frond number were made on days 0, 3, 5 and 7. Fronds were harvested for measurement of dry weight after 7 days. The initial dry weight was determined using a sample of 11 fronds identical to that used to inoculate the test. Temperature was measured continuously, light intensity was recorded at test start and end and pH was recorded on days 0, 3, 5 and 7 days. The test conditions were: 23.4 – 24.1°C, pH 7.88 – 9.23, light intensity 7490 – 9100 lux. The test concentrations were verified by chemical analysis of syn-isomer at days 0 (fresh solutions), 3 (fresh and used solutions), 5 (fresh and used solutions) and 7 (used solutions), using GC-MSD.

The concentrations of the test item in the fresh solutions ranged from 74 to 108 % of the nominal values on day 0, 46 to 87% on day 3 and 96 to 144% on day 5. The concentrations of the test item in the used solutions ranged from 62 to 90 % of the nominal values on day 3, 77 to 112% on day 5 and 75 to 89% on day 7. As the geometric mean measured concentration of the highest test concentration was 83% of nominal, nominal concentrations were used for reporting the results. No signs of toxicity were observed up to the highest tested concentration. The 7-day ErC50 and EyC50 could not be calculated as there was no inhibition of growth. For frond number, the 7-day EyC50 and ErC50 were both > 500 μg/L, based on nominal concentrations. For dry weight, the 7-day EyC50 and ErC50 were both > 500 μg/L, based on nominal concentrations. The 7-day NOEC was determined to be 500 μg/L, based on nominal concentrations, while the LOEC could not be determined.