FRESNO, Calif. -- The nation's capital of intravenous drug use is not New York or Miami, not Chicago or Detroit -- but Fresno.
It is an unlikely distinction for a city of fewer than 500,000 people in the heart of one of the nation's richest agricultural regions.
The percentage of people shooting up heroin and other drugs in Fresno is nearly three times the national average, fueled by a boom in methamphetamine use, according to a study issued last month.
''This town is so full of meth," said Amy Wilson, 28, who was ordered into rehab after her daughter, now 3 months old, tested positive for methamphetamine at birth. ''My grasp on reality was gone," she said. She described drug use in California's Central Valley as ''like a cancer."
Law enforcement agencies and treatment counselors say they are overwhelmed by the scope of the problem, which is compounded by HIV and hepatitis C infections that come from sharing needles.
The Fresno area has become home to Mexican drug cartels that operate in its rural expanses, where the farm chemicals used to make meth are readily available and the noxious fumes are less easily detected. According to a 2001 estimate by the US Drug Enforcement Administration, 80 percent of the country's meth comes from the cartels.
Part of the problem in the Fresno area is also poverty, said Samuel Friedman, a research fellow at the National Development and Research Institutes in New York and primary author of the study in last month's Journal of Urban Health.
Fresno County, where farmworkers get paid rock-bottom, seasonal wages, is one of the poorest counties in the nation. More than 20 percent of its residents -- an estimated 165,000 people -- live in poverty, according to Census estimates, and the per capita income is $15,495 a year.
In the study, Fresno was found to have 173 IV drug users for every 10,000 people; the national average is 60 per 10,000 people. Three other urban areas within 200 miles also made it into the top 10 -- San Francisco, Stockton-Lodi, and Bakersfield.
It is a problem that has been costly for the government. Fresno County spends $20 million a year on drug treatment programs that served more than 9,000 people in 2002, and the programs are straining to keep up with demand.
''Now at least we have a waiting list," said Dennis Koch, administrator of Fresno County's Alcohol and Drug Program. ''Before, we used to not have these programs. There was nothing to wait for."
Meanwhile, the number of addicts who shoot up with dirty needles has placed a heavy burden on public health.
A recent Fresno County study found that 75 percent of the area's injection drug users had hepatitis C, compared with 2 percent of the general population. The county had 251 new HIV infections last year, a 17 percent increase from the previous year.
Last month, Governor Arnold Schwarzenegger signed a law that makes it easier for drug addicts to buy clean needles. Currently, hypodermic needles can be sold without a prescription in only a few circumstances, such as to diabetics who need insulin.
''We can't stop all the drug use in this community," Koch said, ''but there can be safer ways."