The scientists who sequenced the marijuana plant say they hope the next generation of pot will have stronger therapeutic compounds. JUAN MABROMATA/AFP/Getty Images hide caption

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An increase in toxic chemicals in cigarettes may also be to blame for the high risk of bladder cancer for women who smoke. iStockphoto.com hide caption

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A vendor sells betel leaf wrapped in silver foil in Lucknow, India. AJAY KUMAR SINGH/ASSOCIATED PRESS hide caption

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Dr. Paolo Macchiarini, of Karolinska University Hospital, implants a synthetic windpipe. Karolinska Institute hide caption

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Katie Couric at the "Make That Call" For Colon Cancer Screening campaign launch in New York in March. Slaven Vlasic/Getty Images hide caption

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From left, Priscilla Howard, Crystal Hanna and Nancy Haunty, all breast cancer patients, listen at a Food and Drug Administration hearing on Avastin in Silver Spring, Md., on Tuesday. Joshua Roberts/Bloomberg via Getty Images hide caption

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