No drug has fueled the current spike in overdose deaths more than fentanyl. The synthetic opioid claimed two thirds of the record 64,000 such fatalities in the U.S. in 2016.

Up to 100 times more potent than morphine, this compound has played a significant role in reducing Americans’ life expectancy for the second straight year. In three states—Rhode Island, New Hampshire and Massachusetts—the drug was found responsible for at least 70 percent of opioid-related deaths, in what drug-harm reduction specialists have described as “slow-motion slaughter.”

Jess Tilley, a harm-reduction veteran in Northampton, Mass., deploys several outreach teams to rural areas. They pass out clean syringes and the overdose-reversal drug naloxone—and refer people to detox programs. But Tilley’s most in-demand item is a $1 testing strip that accurately detects the presence of fentanyl, which dealers sometimes add to boost the strength of illicit drugs.

In 2016, when the overdose rate in western Massachusetts doubled in a year, Tilley bought a thousand fentanyl testing strips—a low-tech device that resembles a pregnancy test—from a Canadian company, and began distributing them to drug users. She says the response was immediate. As demand skyrocketed, she also began asking low-level drug dealers to test their supplies for fentanyl. Tilley says they began regularly pulling tainted supplies from the market. “When people get a tangible result, it changes behavior,” says Tilley, executive director of the nonprofit New England User's Union. “I’ve been able to track behavior trends. People say when they get results [from the strips], they’re cutting back half of what they’re doing, or they’re making sure they have someone with them when they get high.”

A study released in February reinforces Tilley’s anecdotal accounts. Conducted by Johns Hopkins and Brown universities, the study examined three technologies for testing fentanyl in street drug supplies, and looked at how such testing influenced fentanyl use behavior. The strips (based on an immunoassay, which uses the bonding of an antibody with an antigen to detect the presence of fentanyl) proved most reliable according to the study, detecting fentanyl with 100 percent accuracy in drug samples from Baltimore and 96 percent accuracy in those from Rhode Island.

Another testing method, the Bruker Alpha machine, uses infrared light to pinpoint the various chemical properties of a substance. An analytics program then reads the scan and matches it to a library of hundreds of substances. The $20,000 machine provides a full spectrum of a drug's properties and breaks down its composition in percentages. In the study Bruker Alpha also showed high rates of sensitivity (when fentanyl was present) and specificity (when fentanyl was not present)—but its rates were still reported as lower than those of the strips.

The third device the study examined, the TruNarc machine, uses spectroscopy to detect molecular vibrations in drugs and thus establish their chemical makeup. As TruNarc’s name implies, law enforcement agencies often use it to scrutinize substances obtained in drug seizures. Although it is user-friendly—it is handheld and has an LED screen—study co-authors said it typically detects only the two most prevalent drugs in a substance.

“It’s an important study, and it shows that the fentanyl test can be really used as a point-of-care test within harm-reduction programs,” says Jon Zibbell, a public health scientist at nonprofit research organization RTI International. “The one limitation of the test strips is that they are not quantitative—they don't tell you how much product is there.”

Zibbell, a former health scientist at the U.S. Centers for Disease Control and Prevention who was not involved in the new study, says he is working on his own fentanyl-testing research. He believes the logical next step for opioid-deluged communities would be to set up local facilities where users can have their drugs subjected to a more quantitative and qualitative analysis. “If we really want to deal with the myriad of drugs that are in these products,” he says, “we need to have labs where people can drop their stuff off and have a result in real time. That would increase knowledge, increase safety and, at the end of the day, reduce overdose fatalities.”

The Johns Hopkins researchers indeed found 70 percent of the 355 users interviewed for the study said that if they knew a substance contained fentanyl, they would either not consume it at all, would use it more slowly or would use it in the company of someone who has naloxone—an overdose-reversal medication that can be injected or sprayed through the nostrils.

All three testing technologies are available to public health service providers—and that is where the study’s authors see the most promise. “I think the strips will be scaled up because they’re relatively inexpensive. You’re enabling [users] to do something safely that they’re already doing, and keeping them alive long enough to go to treatment,” says study co-author Susan Sherman, a professor at the Johns Hopkins Bloomberg School of Public Health. “We’re at this critical point in the epidemic where the same-old is not working. The point is there are a lot of answers.”

With the fentanyl crisis showing no signs of relenting, several states are aggressively looking for unconventional solutions—some of which operate in gray areas with regard to federal drug laws. New York State makes public money available for several needle exchanges to buy fentanyl-testing strips, an approach mirrored by California’s Department of Public Health.

And there are signs of shifting attitudes toward addressing the overdose epidemic. Cities across the U.S. are eyeing safe consumption spaces, an approach some European countries have used for decades to reduce deaths and infectious diseases. San Francisco’s Health Commission recently voted to open two safe injection sites this summer. Philadelphia announced similar plans in January. Harm reductionists say these proposed consumption spaces would be ideal locations for the Bruker Alpha machine and the fentanyl testing strips.

Alex Kral, an epidemiologist and Zibbell’s colleague at RTI, says the testing strips are already being distributed at a secret drug injection facility in a major U.S. city. Its location remains undisclosed because the federal government does not sanction it. Besides that, Kral says an increasing number of social services agencies across the country are now handing out the fentanyl test strips.

“I see the strips as one avenue,” says Kral, who was not involved in the new study. “The overdose epidemic right now, in part, is a poisoning epidemic. People are using [fentanyl] without knowing that they’re using it. That’s really the key component here. So the more we can have people know whether their drug is poisoned or not, that’s a good thing.”