Canadian ecosystems support significant biodiversity, with approximately 80,000 plant and animal species known to exist in Canada and potentially more yet to be discovered. Some species are more sensitive to particular substances while others may be less affected due to differences in their physiology, behaviours, or geographic distributions.
The Government of Canada publishes water quality guidelines (guidelines) and also develops predicted no-effect concentrations (PNECs) in their ecological risk assessments. These aim to identify the concentration of a substance in the environment below which adverse effects are unlikely to occur, typically following chronic or long-term exposure.