2,6-di-tert-butylphenol

Endpoint summary

Description of key information

The most sensitive endoints were:

short-term: 48h-Daphnia magna EC50: 0.45 mg/L

long-term: 21d-Daphnia magna NOEC: 0.035 mg/L

Additional information

The environmental hazard assessment for (fresh-) water organisms and sediment habitats is supported by several acute studies (pelagic compartment), a chronic Daphnia reproduction study, NOEC values for algal tests and by using scientific argumentation (sediment dwelling organisms).

For the environmental hazard assessment of 2,6-DTBP acute toxicity studies for freshwater fish, invertebrates (Daphnia magna and Gammarus fasciatus), freshwater algae and STP microorganisms are available. In addition, a long-term Daphnia reproduction study and 96h-NOEC data from algae studies is available. A long-term study for fish is waived since a long-term study is available for the more sensitive group, e.g., the daphinds. Experimental information about toxicity on marine organisms is not available.

The short-term EC50/LC50 values for fish, Daphnia, algae and microorganisms were 1.4, 0.45, 1.2 and > 1000 mg 2,6 DTBP/L, respectively. In addition, a 96h-test with the sediment dweller Gammarus fasciatus is available resulting in a 96h-EC50 of 0.6 mg/L. Gammarus fasciatus is less sensitive than Daphnia magna.

The daphnids (Daphnia magna) were the most sensitive trophic level/species in short-term tests having an EC50 of 0.45 mg/L. Consequently, this species was used also for chronic testing. The long-term test with Daphnia magna resulted in a 21 day-NOEC (mortality, reproduction, growth) of 0.035 mg/L. This value of 0.035 mg/L will be used for the risk assessment of aquatic organisms.

2,6-DTBP has a log Pow of < 5, and the calculation of the PEC/PNEC ratios using the EPM resulted in values < 1. Consequently sediment toxicity tests do not need to be conducted. This is supported by the finding that In an acute 96h-study Gammarus fasciatus is less sensitive when compared to Daphnia magna.