What is PNEC and how is it calculated?

What is PNEC and how is it calculated?

PNEC (Predicted No-Effect Concentration) refers to the highest concentration used in environmental risk assessment of a substance and estimated not to have harmful effects in a specific environment (e.g. water, soil). PNEC is used in environmental risk assessments to determine the potential effects of a substance on the environment.

PNEC calculation generally includes the following steps:

Collection of Toxicological Data: Data obtained from laboratory tests are collected to determine the ecotoxicological effects of the substance. These data include parameters such as LC50 (Lethal Concentration 50), EC50 (Effective Concentration 50), NOEC (No Observed Effect Concentration).

Determination of Assessment Factor: The PNEC value is calculated by dividing the collected toxicological data by an assessment factor. The assessment factor varies depending on the reliability of the data and the scope of the tests.

PNEC Calculation: PNEC is usually calculated with the formula:

PNEC = (NOEC or EC50) / Assessment Factor

For example, if the NOEC value of a substance in the aquatic environment is 10 mg/L and the assessment factor is 100, the PNEC is calculated as follows:

PNEC = 10 mg/L / 100 = 0.1 mg/L

This calculation is used to assess the environmental risks of the substance and to determine safe concentration levels.