4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol

Endpoint summary

Additional information

Acute toxicity tests for Mortrace SB Conc. were available with two species of fish (Cyprinus carpio and Danio rerio), an invertebrate (Daphnia magna), and an aquatic algae (Scenedesmus subspicatus). The key parameters for these acute toxicity tests were a 96-hour LC50 of 10 μg/L for the acute fish study with carp, a 48-hour EC50 of 10 μg/L (based on an initial loading rate of 45 mg/L and an assumption of measured concentrations approximating those in the acute fish toxicity study) for D. magna, and a 72 -hour ErC50 for the algae of 6.7 μg/L (based on an estimation of inhibition of growth rate). While there were no measured concentrations of Mortrace SB Conc in the acute study with Daphnia magna, the toxic potency of Mortrace SB Conc for D. magna was in the same range of water accommodated fractions as was observed in the fish toxicity test, and these water accommodated fractions corresponded to a Mortrace SB concentration approximating the minimum detection level of 10 μg/L. Of these toxicity values, the 72-hour ErC50 of 6.7 μg/L for growth inhibition in the algae was the lowest value reported, and this data point was used in the development of the PNECaqua.

Additionally, one toxicity to microorganisms study with Mortrace SB Conc was available. A 30-minute EC50 value of > 100 mg/L was reported for Mortrace SB Conc based on only slight levels of respiration inhibition (10.4%) at the highest tested concentration of 100 mg/L (initial nominal loading rate). Additionally, the respiration rate of aerobic waste water bacteria was not inhibited when exposed to the lowest test concentration of 10 mg/L, so 10 mg/L is the NOEC in this study.