More than a million people in the US inject drugs frequently, at a cost to society in health care, lost productivity, accidents, and crime of more than $50 billion a year. People who inject drugs imperil their own health. If they contract HIV or hepatitis, their needle-sharing partners, sexual partners and offspring may become infected. It is estimated that half of all new HIV infections in the US are occurring among injection drug users (IDUs). For women, 61% of all AIDS cases are due to injection drug use or sex with partners who inject drugs. Injection drug use is the source of infection for more than half of all children born with HIV. Injection drug use is also the most common risk factor in persons with hepatitis C infection. Up to 90% of IDUs are estimated to be infected with hepatitis C, which is easily transmitted and can cause chronic liver disease. Hepatitis B is also transmitted via injection drug use. Needle exchange programs (NEPs) distribute clean needles and safely dispose of used ones for IDUs, and also generally offer a variety of related services, including referrals to drug treatment and HIV counseling and testing.