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Ecotoxicological information

Toxicity to aquatic plants other than algae

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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 ErC50 based on dry weight was determined to be 3.49 mg/L, the ErC10 based on dry weight was determined to be 0.97 mg/L and the NOEC was determined to be 0.63 mg/L

Key value for chemical safety assessment

EC50 for freshwater plants:
3.49 mg/L
EC10 or NOEC for freshwater plants:
0.97 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 following 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, 16-fold diluted filtrate of a loading of 2.5 mg/L plus the control. 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 test item is a complex mixture. Every constituent of the mixture 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 24 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 analyzed. 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 renewals and at exposure termination analyses were performed in samples of the filtrate of a loading of 10 mg/L, 16-fold diluted filtrate of a loading 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 3.19 – 6.28 mg C/L in the test item concentrations. At the first renewal, in spent 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 3.05 – 6.19 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) – 1.12 mg C/L in the control, in the range of 2.84 – 3.33 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 5.25 – 6.26 mg C/L in the test item concentration: filtrate of a loading of 10 mg/L. During exposure, in spent samples the analysed total organic carbon concentration were: below the LoQ value (<1.0 mg C/L) in the control, in the range of 2.42 – 3.13 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 4.93 – 6.14 mg C/L in the test item concentration: filtrate of a loading of 10 mg/L. 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 3.49 mg/L, the ErC10 based on dry weight was determined to be 0.97 mg/L and the NOEC was determined to be 0.63 mg/L.