Persistence (environmental)

Chemicals disappear from the environment through several routes: breakdown by microorganisms, reaction with sunlight, hydrolysis in water and other chemical reactions. A substance that resists all of these lingers. Because exposure continues for as long as it is present, persistence multiplies other hazards such as toxicity and bioaccumulation.

Persistence is often described using half-life, the time for half the amount to degrade, but a single figure rarely captures it. Breakdown in a warm, oxygen-rich river is not the same as in cold deep sediment, so half-life depends on the compartment and conditions.

Regulators treat persistence as a key screening property. Under REACH, a substance that is persistent, bioaccumulative and toxic is a particular concern, and the same combination features in several national programs. Persistence also affects whether a release is considered a long-term environmental problem rather than a short-lived one.

For users, persistence is a reason for careful disposal. A persistent chemical washed to drain or soil may remain in water supplies or ecosystems well beyond the time of your work. The SDS entry is a starting point rather than a full environmental assessment.