The increasing levels of U.S. heroin use, which has reached epidemic proportions during the past five years, stems from a corresponding spike in abuse of prescription opiate-based painkillers, such as oxycodone, Drug Enforcement Administration officials said.
Many individuals who start out abusing oxycodone turn eventually to heroin as they build up a tolerance to the pain pills and find that they can buy heroin far more cheaply than prescription medications on the black market, the officials said.
"Oxy is much more expensive to get than heroin," said Sarah Pullen, a special DEA agent in Los Angeles. "Prescription drug abuse really took hold about 10 years ago, and about five years ago, we really started to see heroin abuse pick up."
The amount of heroin seized annually along America's Southwestern border has increased nearly four-fold between 2008 and 2012, from 558.8 kg (1,232 lb) to 2,091 kg (4,610 lb) per year, a sign that smuggling operations are on the rise, the DEA said.
Ninety-five percent of the heroin smuggled into the United States originates in South America, much of it in Mexico, the agency said.
Meanwhile, fatal heroin overdoses have increased 45 percent from 2006 to 2010, with 3,038 such deaths reported that year, and numbers are believed to still be on the rise, the agency said.
Possible reasons cited for the rise in heroin deaths include a general increase in abuse of the drug, an increase in the availability of high-purity heroin at the street level, and a growing number of people using the narcotic at a younger age.
Authorities in the Northeast said they have seen a rash of fatal overdoses in recent months attributed to a deadly brand of heroin laced with fentanyl, an opioid that is 50 to 100 times more potent than morphine and 30 to 50 times more powerful than heroin.
Law enforcement sources told Reuters investigators were trying to determine whether the heroin that is suspected of killing Philip Seymour Hoffman, 46, might have been laced with fentanyl.
The Oscar-winning actor, who had a history of substance abuse, was found dead in the bathroom of his Manhattan apartment on Sunday, with a syringe stuck in his arm. New York City police sources familiar with the case said 50 small bags of what appeared to be heroin were found in his home.
An autopsy of the actor's body was performed on Monday, but it was not known when results would be released.
Dr. Marvin Seppala, the chief medical officer at the Hazelden drug addiction treatment centers, said heroin and other opioids lend themselves to overdose and death because they directly act on the parts of the brain that control breathing.
Erin Mulvey, a DEA special agent in New York City, said additives such fentanyl are added to heroin at local distribution centers where pure heroin smuggled into the United States is processed and packaged for street sales.
She said 17 percent of all heroin seized by authorities in recent years has been confiscated in New York, a sign that the city is a major U.S. distribution hub for the drug.
The DEA had no nationwide data quantifying the incidence of overall heroin use independent of overdose deaths.
But the Los Angeles Times cited figures from a neuropharmacology professor at Washington University in St. Louis, who said the percentage of addicts seeking treatment for heroin abuse at 150 drug treatment centers across the country has increased from about 10 percent in 2011-2012 to between 20 and 25 percent over the past year.