5,5'-sulfonylbis(2-benzofuran-1,3-dione)

Short-term toxicity to aquatic invertebrates

Description of key information

Test results with pH adjustment at 100 mg/L: 
Based on the nominal concentrations of the test item 4,4‘-Sulfonyldiphthalic acid dianhydride (DSDA), the 48 hour-EC50 for Daphnia magna was > 100 mg/L. 
The NOEC after 48 hours was ≥ 100 mg/L. The LOEC after 48 hours was > 100 mg/L.

Additional information

At the pH-adjusted nominal test item concentration of 100 mg/L of the test item 4,4‘-Sulfonyldiphthalic acid dianhydride (DSDA) and the other concentration levels of 15.3 to 62.5 mg/L, which remained in a pH-neutral range (pH 6.09 - 7.70), effects could not be observed on immobilisation of Daphnia magna after 48 hours. At the concentration level of 100 mg/L in test media without pH adjustment with a resulting solution pH of 4.32 - 4.62, a 100 % immobilisation was observed after 24 hours. The test item remained in solution in pH-adjusted and pH–unadjusted solutions as recoveries of ≥ 85%, i.e., the hydrolysis product, after 48 hours range from 85 to 102%. Thus, Daphnia magna were exposed to the hydrolysis product in solutions with and without pH adjustment. Therefore, observed effects are assumed to be pH-related and are not assumed to be toxic effects of 4,4‘-Sulfonyldiphthalic acid dianhydride (DSDA). The absence of observed toxic effects at 100 mg/L in pH adjusted solutions indicates the lack of a hazardous potential since the pH of aquatic systems is typically well buffered.