According to the 2009 National Survey on Drug Use and Health (NSDUH), 16.7 million people age 17 or older were current marijuana users, meaning they used the drug during the month prior to taking the survey. In 2009, there were 2.4 million new past-year users of marijuana, and the average age of initiation declined from 17.8 years old in 2008 to 17 years old in 2009. The rate of past-month marijuana use among 12-to-17-year-olds increased to 7.3 percent. The average potency of marijuana has more than doubled since 1998. Delta-9-tetrahydrocannabinol (THC), which is the main active ingredient in marijuana, acts upon specific sites in the brain called cannabinoid receptors, triggering a series of cellular reactions that produce the "high" users experience when they smoke the drug. Marijuana intoxication can cause distorted perceptions, impaired coordination, difficulty in thinking and problem solving, and problems with learning and memory. Studies have shown a link between chronic marijuana use and increased rates of anxiety, depression, suicidal thoughts, and schizophrenia. In order to reduce the prevalence of marijuana use, particularly among youth, the Federal Government is implementing multi-sector, community-based methods of prevention and intervention, such as the Drug Free Communities program; the National Youth Anti-Drug Media Campaign; and the implementation of the model of screening, brief intervention, and referral to treatment. Although there are no medications for treating marijuana abuse, behavioral interventions have proven effective in treating marijuana dependence. The increasing number of outdoor marijuana cultivation sites often result in the destruction of natural habitat due to diesel spills, pesticide runoff, and trash from cultivators. 25 notes