Hydrogen [3-[(4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo]-2-hydroxy-5-nitrobenzenesulphonato(3-)]hydroxychromate(1-), compound with 3-[(2-ethylhexyl)oxy]propylamine (1:1)

Toxicity to aquatic plants other than algae

Description of key information

The toxicity of the test substance to Lemna gibba was determined in a study (Institute of Industrial Organic Chemistry, 2017) according to the principles of OECD 221 (2006). After 7 days, the ErL50 based on dry weight was determined to be 1.44 mg/L, the ErL10 based on dry weight was determined to be 0.39 mg/L and the NOEC was determined to be 0.16 mg/L

Key value for chemical safety assessment

EC50 for freshwater plants:

1.44 mg/L

EC10 or NOEC for freshwater plants:

0.39 mg/L

Additional information

The toxicity of the test substance to Lemna gibba was determined in a study (Institute of Industrial Organic Chemistry, 2017) according to the principles of OECD 221 (2006). The growth of Lemna gibba exposed to the test item was investigated in a 7 day semi-static test with daily renewals. The definitive test was performed using seven test item concentrations: filtrate of a loading of 10 mg/L, filtrate of a loading of 5 mg/L, filtrate of a loading of 2.5 mg/L, 2-fold diluted filtrate of a loading of 2.5 mg/L, 4-fold diluted filtrate of a loading of 2.5 mg/L, 8-fold diluted filtrate of a loading of 2.5 mg/L and 16-fold diluted filtrate of a loading of 2.5 mg/L plus the control (with a spacing factor of 2.0). The test item concentrations were split up into three replicates, the control was split up into six replicates. The test was performed in glass crystallizers containing 150 mL of each treatment per replicate. The dilutions of the loading rate 2.5 mg/L were denominated 1.25 mg/L, 0.63 mg/L, 0.31 mg/L and 0.16 mg/L, respectively. The test item is a complex mixture. Every constituent contributes to a different degree to overall solubility, depending on its own individual solubility and its mass fraction in the test item. For this reason, the loading rates were prepared by using the water accommodated fraction (WAF) approach followed by filtration. The test item loading rates were prepared by mixing the proper amounts of the test item with the 20X AAP medium. The test item loading rates and the control were mechanically shaken for 48 hours, followed by a 24 hours settling phase and filtration, first through a conditioned paper filter and next through a conditioned nitrocellulose membrane filter. The conditioning was by pre-filtering a small volume of either test item concentrations or the control to saturate the filter (and disposing it) before filtering the volumes for exposure. The preparation of the lowest four exposure levels was not technically feasible in form of separate loading rates. That is why they were prepared as sequential dilutions of the loading rate 2.5 mg/L with 20X AAP medium. In the definitive test, total organic carbon (TOC) was analysed. This analytical approach did not account for any degradation or metabolisation effects which may have occurred during exposure. The results were corrected by the value determined for the control sample in a series and presented as the concentrations of total organic carbon (TOC). At exposure initiation and at the first renewal analyses were performed in samples of each test item concentration and the control. On the following renewal and at exposure termination analyses were performed in samples of the filtrate of a loading of 10 mg/L, 16-fold diluted filtrate of 2.5 mg/L and the control. At exposure initiation, in fresh samples the analysed total organic carbon concentration was below the LoQ value (<1.0 mg C/L) in the control and in the range of 2.83 – 7.17 mg C/L in the test item concentrations. At first renewal, in old samples the analysed total organic carbon concentration was below the LoQ value (<1.0 mg C/L) in the control and in the range of 2.76 – 6.86 mg C/L in the test item concentrations. During exposure, in fresh samples the analysed total organic carbon concentration were: below the LoQ value (<1.0 mg C/L) – 1.04 mg C/L in the control, in the range of 2.55 – 4.06 mg C/L in the testitemconcentration: 16-fold diluted filtrate of a loading of 2.5 mg/L and in the range of 5.43 – 6.99 mg C/L in the test item concentration: filtrate of a loading of 10 mg/L. During exposure, in old samples the analysed total organic carbon concentrations were: below the LoQ value (<1.0 mg C/L) in the control, in the range of 2.40 – 3.35 mg C/L in the test item concentration: 16-fold diluted filtrate of a loading of 2.5 mg/L and in the range of 5.10 – 6.25 mg C/L in the test item concentration: filtrate of a loading of 10 mg/L. The endpoint values were determined as loading rates of the nominal test item concentration.A blank control with the test solution without test material and a reference control with the reference substance 3,5-dichlorophenol were performed. After 7 days the ErC50 of the reference substance 3,5-dichlorophenol was determined to be 9.94 mg/L. The validity criteria were fulfilled. After 7 days, the ErC50 based on dry weight was determined to be 1.44 mg/L, the ErL10 based on dry weight was determined to be 0.39 mg/L and the NOEC was determined to be 0.16 mg/L