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

Workers for the Safe Streets violence interruption project including Gardnel Carter, center, talk with Baltimore residents in 2010. Kenneth K. Lam/MCT via Getty Images hide caption

itoggle caption Kenneth K. Lam/MCT via Getty Images

A package of synthetic marijuana, or spike. Steve Featherstone hide caption

itoggle caption Steve Featherstone

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

itoggle caption Spencer Platt/Getty Images

Donetta Held unloads needles and pipes confiscated from a contaminated meth home. She owns an environmental decontamination company and says meth tests are their most demanded service. Barbara Brosher/WFIU hide caption

itoggle caption Barbara Brosher/WFIU

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

Tom Robichaud launched his business, Discreet Intervention, six months ago. Here, he works his dog in a vacant office building, hitting on a cylinder containing cocainelike drugs. Pat Greenhouse/Boston Globe via Getty Images hide caption

itoggle caption Pat Greenhouse/Boston Globe via Getty Images

A man walks past a fresh grave in the Kamar Kulagh slum outside of Herat. David P. Gilkey/NPR hide caption

itoggle caption David P. Gilkey/NPR

Joaquin "El Chapo" Guzman is escorted to a helicopter in handcuffs by Mexican navy marines at a navy hanger in Mexico City on Saturday. A senior U.S. law enforcement official said that Guzman, the head of Mexico's Sinaloa Cartel, was captured alive overnight in the beach resort town of Mazatlan. Eduardo Verdugo/AP hide caption

itoggle caption Eduardo Verdugo/AP