The persistence of a substance reflects the potential for the substance to reach the marine environment and to be transported to remote areas as well as the potential for long-term exposure of organisms. 
Persistence is one of 3 important criteria used to asses the environmental impact of a chemical substance. The other 2 are bioaccumulation and toxicity. According to OSPAR criteria a substance should be considered persistent, if it is likely to end up in the marine environment with a half-life above 50 days. 
- OSPAR CONVENTION 2005, Cut-Off Values for the Selection Criteria of the OSPAR Dynamic Selection and Prioritisation Mechanism for Hazardous Substances Citefout: Ongeldig label
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