Narrator: This is Science Today. A recent report in an environmental journal has found butter may be one way to monitor airborne pollution. According to the scientists involved in the study, PCBs and other compounds migrate from the atmosphere to the ground, where they are eaten by cows and, in turn, accumulate in dairy fat. Environmental scientist, Thomas McKone of the University of California, Berkeley, says this type of pollutants are what's called persistent organic pollutants.
McKone: Persistent organic pollutants are a class of pollutants that tend to last a very long time. They don't break down in the environment. Some of these last so long that we see them migrating northward into the Artic and starting to show up in terrestrial or aquatic food webs, so they show up in the whales or the seals that live in the Artic Circle because they're so long-lived in the environment.
Narrator: McKone says there is a large, international effort to restrict the use of persistent pollutants.
McKone: Most of the industrialized, and a large fraction of the developing countries have signed onto this treaty to quit making and using persistent pollutants.
Narrator: For Science Today, I'm Larissa Branin.