2-[4-[[2-(cyanoimino)hexahydro-4,6-dioxo-5-pyrimidyl]azo]phenyl]-6-methylbenzothiazole-7-sulphonic acid, compound with 2,2',2''-nitrilotris[ethanol] (1:1)

Short-term toxicity to fish

Description of key information

The acute toxicity of the read across substance (DY137_Similar Substance 01) to Zebrafish (Danio rerio) was determined in a study (BASF SE, 2018) according to OECD 203 (1992) under GLP conditions. The 96 hour LC50 of the test substance was determined to > 111.2 mg/L based on the mean measured concentrations.

Additional information

In a 96 hour acute toxicity key study, zebrafish (Danio rerio) were exposed to the read across substance (DY137_Similar Substance 01) at nominal concentrations of 0 (control) and 250 mg/L under static conditions in accordance with the OECD 203 (1992) and in compliance with GLP principles (BASF SE, 2018). The water pH, temperature and dissolved oxygen were within acceptable guideline specifications. The initial measured concentration of the test substance was 44 % of the expected nominal concentration at the start of exposure and 45 % of the expected nominal concentration at the end of the exposure. This deviation from the nominal value is likely due to the poor solubility of the test chemical in test medium. Undissolved test substance was removed by a centrifugation step prior to analysis. After 96-hours of exposure, the measured concentration was 100 % of the initial measured value. Thus, the test substance was stable in solution under test conditions and mean measured concentrations are an accurate representation of exposure levels maintained throughout the test period. The results in this study are consistent with all validity criteria and the test is valid according to the guidelines of this study. No deviations from test guidelines or other incidents occurred during the course of the reported test which may have influenced the results. The 96 hour LC50 was > 250 mg/L based on the nominal concentration of the test substance and > 111.2 mg/L based on the mean measured concentrations. The test substance had no observable acute effect on fish up to 111.2 mg/L in test media and under test conditions.

In addition the acute toxicity of the read across substance (DY137_Similar Substance 01) to bluegill sunfish Lepomis macrochirus Refinesque was determined according to OECD 203 under GLP conditions in a supporting study (UCCES, 1979). Groups of ten fish were exposed for 96 hours to nominal concentrations of 180, 320, 560, 1000 and 1800 mg/L of the read across substance. At the beginning of the test and every 24 hours thereafter dissolved oxygen and pH of the control and each test concentration, and temperature of the water bath, were determined. Mortalities and abnormal behavioral responses were recorded every 24 hours. As a result, no mortalities occurred; therefore, the LC50 was determined to be greater than 1800 mg/L. As fish of all test groups showed behavioral abnormalities (swimming near the surface), the NOEC was found to be < 180 mg/L.

Furthermore, the LC50 (96 h) was determined to be greater than 1000 mg/L in a supporting study (BASF SE, 1985) conducted with the test item on zebra fish. As only limited details are available and the concentration of the test substance in the preparation was not clear, the validitiy of the study was regarded as not assignable.