RICHMOND, Va., June 13 /PRNewswire/ -- Opioid addiction, particularly to heroin, is a rapidly growing public health threat in the greater Washington, D.C. area. According to a recent government report, as many as 18,000 D.C. residents are addicted to heroin. Heroin is one of the three most frequently abused drugs in the District, and was the primary substance of abuse for more than 40% of substance abuse treatment admissions in 2003. Thousands more Washington-area residents also seek treatment for opioid dependence due to misuse of prescription painkillers such as oxycodone, hydrocodone, and morphine.