Glossary / Ecology
PNEC
A PNEC, or Predicted No-Effect Concentration, is the concentration of a substance in an environmental compartment, such as fresh water, sediment or soil, below which adverse effects on organisms are not expected. It is derived from ecotoxicity data with safety factors applied.
Explanation
To set a PNEC, assessors begin with the most sensitive reliable result from tests on fish, invertebrates and algae, such as an EC50 or a no-observed-effect concentration. They then divide by an assessment factor that reflects how much data exist and how uncertain extrapolation from lab to field is. Less data means a bigger factor and a lower PNEC.
PNECs are set for separate compartments: fresh water, marine water, sediment, soil, sewage treatment plants and sometimes predators through the food chain. The risk is judged by comparing the predicted environmental concentration from releases with the PNEC. If the ratio is below one, the risk is considered controlled.
PNEC is the environmental counterpart of the DNEL, which protects people. Both are concepts from REACH and appear in chemical safety reports and extended safety data sheets. They are not binding limits in themselves, but companies use them to design controls and to justify the conditions of use they recommend.
For a facility, PNECs explain why some discharge or release controls are so strict for particular products. If the SDS lists a very low PNEC, small leaks and drain disposal are a real concern.
What to do and watch for
- Treat a very low PNEC as a signal to prevent any release to drains or water.
- Check which compartment the value covers.
- Use the supplier's recommended risk management measures for the use.
Where it appears on an SDS
- Section 12: Ecological information. Ecotoxicity data that PNEC values are based on, with PNECs sometimes given in extended SDSs.
- Section 8: Exposure controls / personal protection. Environmental exposure controls and, for REACH substances, PNEC values in the exposure control details.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.