Disodium 2-[4-[[1-[[(2-methoxy-5-methyl-4-sulphonatophenyl)amino]carbonyl]-2-oxopropyl]azo]phenyl]-6-methylbenzothiazole-7-sulphonate

Toxicity to aquatic plants other than algae

Description of key information

The growth of Lemna gibba exposed to the test item was investigated in a 7 day static test (BASF SE, W/26/16, 2016) according to OECD 221 (2006). The ErC10/7 d was determined to be higher than 117 mg/L and the NOEC/7 d was determined to be higher than or equal to 117 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for marine water plants:

117 mg/L

Additional information

The growth of Lemna gibba exposed to the test item was investigated in a 7 day static test according to OECD 221 (2006). The test was performed in glass beakers containing 400 mL of each treatment per replicate. In the test Lemna gibba of initial three plants of three fronds were exposed to five test item concentrations of 7.31, 14.63, 29.25, 58.5, 117 mg/L plus the control (what corresponds to 6.25, 12.5, 25, 50 and 100 mg/L of main ingredient). Additional control with ammonium added was done to determine the impact of ammonium on test organism. During exposure, in all test item concentrations no distinctive changes from the normal development of plants in the control were observed. Moreover, in the additional control with ammonium added no distinctive changes from the normal development of plants in the control were observed. The content of main ingredient in the test item concentration was determined with a validated spectrophotometric method. In the samples collected at exposure initiation the determined main ingredient concentrations were in the range of 89.8 - 95.5% of nominal concentration. Therefore, the results confirm correct preparation of the test item concentrations. In the samples collected at exposure termination the determined main ingredient concentrations were in the range of 88.1 - 90.7% of nominal concentration. The test item concentrations were stable under test conditions. The endpoint values were determined based on the nominal test item concentration.

The ECx values were calculated with a probit method. To make calculations and to conduct statistical analyzes, the ToxRat Professional commercial software was used. The median concentration causing 50% inhibition of growth rate of Lemna gibba culture based on frond number ErC50/7 d is higher than 117 mg/L. The ErC10/7 d is higher than 117 mg/L. The test item concentration at which no growth inhibition effect is observed, i.e. the NOEC/7 d is higher than or equal to 117 mg/L.

The median concentration causing 50% of yield inhibition of Lemna gibba culture based on frond number EyC50/7 d is higher than 117 mg/L. The EyC20/7 d is higher than 117 mg/L and the EyC10/7 d is higher than 117 mg/L. The test item concentration at which no yield inhibition effect is observed, i.e. the NOEC/7 d is higher than or equal to 117 mg/L.