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

itoggle caption Tamika Moore/AL.com/Landov

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

itoggle caption Maddie McGarvey for NPR

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

itoggle caption Ben Allen/WITF

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

itoggle caption Courtesy of Christina Smolke/Stanford University

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

itoggle caption Meredith Rizzo/NPR

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

itoggle caption Spencer Platt/Getty Images

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

itoggle caption Dimitar Dilkoff/AFP/Getty Images

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

itoggle caption Bobby Caina Calvan/Heartland Reporting Project

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

itoggle caption Ben Allen/WITF

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

itoggle caption Laurel Morales/KJZZ

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

itoggle caption David Guttenfelder/AP/National Geographic

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

itoggle caption Karen Brown/WFCR

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

itoggle caption Seth Herald/Nurphoto/Corbis