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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Estradiol was studied for ready biodegradability in three different CO2 evolution tests (according to OECD 301B and US FDA test guideline  TAD 3.11.
The test substance estradiol was incubated in an aqueous solution including nutrients with microorganisms from a municipal sewage treatment plant for 28 days.In the tests under TAD 3.11 the inoculum from the sewage treatment plant is mixed with garden soil and preincubated for 14 days.
The test substance estradiol was incubated in triplicate.Additionally, a reference substance (sodium acetate) was tested according to the same
procedure, in order to verify the viability and activity of the degrading microorganisms. Furthermore, a blank control was tested in triplicate without any test or reference substance. One further set was incubated with sodium acetate plus estradiol representing a toxicity control.
In the tests according to TAD 3.11. the reference substance was aniline.
Results: Estradiol showed a degradation of 67-69 %. However, it was not ready biodegradable, since 60 % biodegradation was not reached after
10 days following the start of the degradation (i.e. when 10% degradation was reached). However, estradiol was mineralized to a significant extent. It was not toxic to the microbes of activated sludge.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

The studies were conducted according to GLP (reports A05658, A05659, A05814)