A brief but concisely investigative look at a health issue much in the news as of late. Nicely explanatory quotes from credible sources. The links are helpful and informative. Well-written sans bias. The scientific terminology is accessible and readily understandable. A worthwhile read, particularly for those who partake in the referenced activity. (Important Reader Note: UPI (United Press International is owned by News World Corporation which was founded by Sun Myung Moon, of the Unification Church, which is considered in some quarters to be a cult. Also, in 1982 Moon was convicted in the United States of filing false federal income tax returns and conspiracy).