A nasal spray version of the overdose-reversing drug naloxone demonstrated at police headquarters in Quincy, Mass., in 2014. Gretchen Ertl/Reuters/Landov hide caption

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Health worker Nathan Fields (left), Rep. Donna Edwards and Dr. Leana Wen show people how to use naloxone on a street corner in Sandtown, a Baltimore neighborhood where drug activity is common. Andrea Hsu/NPR hide caption

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Heroin sold in the U.S., like this dose confiscated in Alabama last fall, is often cut with other drugs. Tamika Moore/AL.com/Landov hide caption

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A water tower in Marion, Ohio. The city has been gripped by heroin addition. Maddie McGarvey for NPR hide caption

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Cris and Valerie Fiore hold one of their favorite pictures of their sons Anthony (with the dark hair) and Nick. Anthony died from a heroin overdose in May 2014 at the age of 24. Cris Fiore's eulogy described his son's death as a shock, but "not a surprise." Anthony had been addicted to heroin for years. Ben Allen/WITF hide caption

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This genetically modified yeast can convert sugar into powerful opioid drugs. Scientists working with the modified yeast strains are required to register them with the Drug Enforcement Administration and keep the yeast under lock and key. Courtesy of Christina Smolke/Stanford University hide caption

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Leana Wen hands out awards to business owners for their efforts to support breastfeeding at the Baltimore City Health Department on Tuesday. Meredith Rizzo/NPR hide caption

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A user prepares drugs for injection in 2014 in St. Johnsbury, Vt. Spencer Platt/Getty Images hide caption

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A Bulgarian border policeman stands near a barbed wire wall on the border with Turkey in July 2014. Experts believe that about two-thirds of the heroin that enters Europe comes through Bulgaria, and that a third of that moves on to the United States. Dimitar Dilkoff/AFP/Getty Images hide caption

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Sabas Sanchez Jr. was better known among his neighbors in Madison, Neb., as "Gordo" — Spanish for chubby. He also had an oversized personality. His father keeps this tattered photo in his wallet. Bobby Caina Calvan/Heartland Reporting Project hide caption

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Stacy Emminger holds the death certificate for her son, Anthony, who was addicted to heroin. His death was marked as a multidrug toxicity in Pennsylvania. Ben Allen/WITF hide caption

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Shannon Rivers, a member of the Akimel O'odham tribe, lights a fire for the purification ceremony at the Coconino County jail. Inmates will help him put blankets over the sweat lodge structure, place heated rocks inside and pour water over them. Laurel Morales/KJZZ hide caption

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Families harvest poppy bulbs in the Badakhshan province of Afghanistan. To collect the opium, they score the bulbs and let the milky substance ooze out. The dried residue contains about 10 percent morphine. David Guttenfelder/AP/National Geographic hide caption

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Volunteer Patrick Pezzati searches yards in Turners Falls, Mass., for discarded heroin needles. Karen Brown/WFCR hide caption

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Volunteers search for needles and other drug paraphernalia along Church Street in Austin, Ind., in April. The region has recorded 142 new HIV cases since December, according to the state, in an outbreak tied to injected-opioid use. Seth Herald/Nurphoto/Corbis hide caption

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In Philadelphia, some drug users are selling clean needles from needle exchange programs on the street. Researchers say the black market isn't necessarily a bad thing. ImageZoo/Corbis hide caption

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Tina Wolf demonstrates the use of naloxone to community members in Lindenhurst, N.Y., during an overdose prevention training. Georgia Dolan-Reilly (left) of the Suffolk County Prevention Resource Center helped with the training. Kevin Hagen for NPR hide caption

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