Persistent, Bioaccumulative, Toxic (PBT) and very Persistent, very Bioaccumulative (vPvB)
An important part of the approval process for pesticides involves screening for PBT (Persistent, Bioaccumulative, Toxic) and vPvB (very Persistent, very Bioaccumulative) behaviour. If a chemical exhibits some or all of these properties its availability on the market may need to be restricted:
Persistent is a term applied to chemicals that do not break down easily in the environment. Such chemicals can be transported long distances through air and ocean currents. They can remain in the environment for extended periods, be absorbed by plants and microorganisms and enter the food chain.
Bioaccumulation is the accumulation of a toxic chemical in the fatty tissues of an individual organism either directly or indirectly from the environment. The chemical accumulates in these tissues more quickly than they can be metabolized. This poses a threat to these organisms and others higher up in the food chain, including humans, where they can continue to concentrate to toxic levels.
Toxicity includes harm not only to humans but also to individual animals and entire food chains. Toxic effects may include cancers, physical or behavioural reproductive problems, or damage to the endocrine and nervous systems, among others.