While the long-term public health impact of marijuana legalization is yet to be determined, many experts agree that marijuana use is risky for some people and addictive for others. Listen in as host William C. Moyers talks with psychiatrist Marvin D. Seppala, MD, about the health risks of marijuana (especially for teens), the difference between heavy use and marijuana addiction, and how to find help if you're concerned about marijuana use or dependence.