A dorado shimmers below the surface, flitting its radioactive blue fins and flicking its yellow tail as it circles a vertical net dangling from the Hespérides. The dorado is the largest animal we have seen since leaving the African coast. It might see our nets as competition, or as a handily packaged snack. An open ocean predator, the dorado is probably laced with polychlorinated biphenyl (PCBs), one of the compounds subject to limits by the Stockholm Convention on Persistent Organic Pollutants (POPs).
Despite successful international efforts to limit the use of early pollutants such as dichlorodiphenyltrichloroethane (DDT), people continue to invent new substances which leak from everyday use into the wider environment. Some of those chemicals break down quickly under the sun’s ultraviolet rays or by mixing with water. They pose little long-term threat. Researchers refer to more durable chemicals as persistent. It’s a good word for the pollutants.
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