By Little Pro on 2016-08-11 Views: Update:2018-02-09
This is the answer to a quiz on how to derive predicted no-effect concentration (PNEC) for a substance (Koc=10) for 4 environmental compartments (water, soil, STP and sediment) based on available data. The original quiz and tutorial can be accessed here.
|PNEC-STP microorganism||EC50(activated sludge inhibition test)=20mg/L||AF=100||0.2mg/L|
|PNEC-soil||LC50 (earthworm acute toxicity) =500mg/kg||
Q2. If the concentration of the substance in water is 0.05mg/L, the risk is acceptable.
For PNEC-water, long-term results (NOEC) from three species are available. An assessment factor of 10 is assigned to the lowest NOEC value of the 3 species.
For PNEC-STP microorganism, only short-term EC50 from activated sludge respiratory inhibition study is available. An assesment factor of 100 is assigned to the EC50.
For PNEC-soil, only one acute test result with soil dwelling organisms is available. PNEC-soil is calculated on the basis of this result using both assessment factor approach and on the basis of the equilibrium partition method (EPM).
In the end, the lowest PNEC-soil value (0.029mg/kg) will be used for soil risk assessment.
For PNEC-sediment, no test data is available. Only EPM can be used.
If the concentration of the substance in water is 0.05mg/L and it is less than PNEC-water, the risk is acceptable.