THINKING ABOUT THE GREEN

After paclitaxel received FDA approval in 1992, supply became a major problem. Each slow-growing yew tree produces only about 10 pounds of bark, and collecting bark can kill the tree. A 1991 study estimated that it would take 625,000 pounds of dried bark to treat 12,000 patients (the number of American women who were dying from ovarian cancer each year). That comes out to 62,480 trees to yield that 55 pounds of pure paclitaxel-about three trees per person. Another study estimated six trees. Today paclitaxel comes from the branches and needles of the Pacific yew trees, which are grown on huge plantations. This method causes no harm to the trees, making it good for business and the environment, the best of both worlds. (Of all the plants native to North America only a few, such as the Pacific yew, have yielded modern drugs.)