Whyever would someone do that?

But cancer is not simply a clonal disease; it is a clonally evolving disease.

The 2,4,5-T used by Courtney and co-workers … was contaminated with approximately 30 ppm of 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin). … The present work describes the results of our teratogenic studies on hamsters with samples of 2,4,5-T containing varying amounts of dioxin and with samples of 2,4-D from different manufacturers.

Audio and video codecs are important in making multimedia files small enough to distribute and simple to play back.