Publisher Health

“You smoke weed?” Eufamia Lopez asked the half-dozen young men lounging on benches in a public housing courtyard in the South Bronx.

The soft September air reeked of the obvious answer.

Ms. Lopez, who works for a New York University health support program, plunged into her spiel. Street drugs — meth, coke, molly, Xanax, heroin and even marijuana — are being cut with fentanyl these days, she said, which can kill you. But you can test your supply before using it to see whether there’s any fentanyl in it. She was giving out free kits.

She had their attention, and not just because she is 5-foot-10, frank but ebullient, with cascading black curls scarcely held in check by a brightly colored scarf. The neighborhood, Mott Haven, has one of New York City’s highest overdose rates. After she recited the simple instructions, each man readily accepted a kit with three fentanyl test strips. One asked for a second kit.

“I appreciate you,” she said, rewarding him with a smile.

The spread of fentanyl, a cheap synthetic opioid 50 times as lethal as heroin, into most kinds of illicit drugs has pushed fatal overdoses to record highs in the United States. Fentanyl test strips have become a popular but contentious tool in response. Supporters say they help drug users make lifesaving decisions. Opponents contend that they facilitate drug use.

Test strips are a part of a broader approach called harm reduction, which holds that ending the overdose crisis can be achieved only by first ameliorating the deadliest risks of drug use, then taking steps to curb behavior, such as addiction treatment. President Biden is the first president to embrace harm reduction, and he has made fentanyl test strips a key component in his proposed $307 million harm-reduction drug-control strategy. Within the past year, about 10 states — including Louisiana, Tennessee, Alabama and Georgia, where hard-line abstinence views are more typically favored — have legalized test strips and made them more available.

But test strips are illegal in about 20 states — including Florida, Texas, Kansas and Kentucky — classified as “drug paraphernalia.”

Critics say test strips encourage drug use by giving users the green light if the supply is free of fentanyl. To some opponents, the test strips are even more objectionable than other forms of harm reduction, like distributions of clean syringes, because those at least prevent the spread of H.I.V., hepatitis and other dangerous infections to users and nonusers.

In May, Kansas legislators blocked a proposal to legalize the strips. “Fentanyl strips don’t save lives. Let’s be clear. There are individuals that want fentanyl in the drug that they’ve purchased or acquired,” Molly Baumgardner, a Republican state senator, said at the time, according to the Kansas Reflector, which reports on state government.

The Biden administration’s drug czar refutes such criticism. “There is no scientific evidence to support this notion that harm-reduction services like fentanyl test strips somehow encourage drug use, but there is significant evidence to support the fact that these tools can save lives,” said Dr. Rahul Gupta, director of the federal Office of National Drug Control Policy.

In fact, there is not yet a substantial body of evidence that directly shows test strips have saved lives. Results have been mixed from a handful of relatively small studies looking at whether the strips deter sustained drug use.

A 2020 study of 68 female sex workers in Baltimore found that after receiving the strips, 84 percent tested their drugs and 69 percent subsequently took precautionary measures, such as asking someone to check on them or using smaller amounts. But a 2018 study looked at a supervised drug injection site in Vancouver, British Columbia, where users were asked whether they wanted to check their drugs (usually heroin) for fentanyl. Scarcely 1 percent chose to do so. Nearly 80 percent of those samples indeed tested positive for fentanyl.

In a 2021 study, researchers at the Johns Hopkins Bloomberg School of Public Health, among others, surveyed 225 drug users in Baltimore and Delaware who had been given strips at two syringe distribution programs. About three-quarters reported having used them. In Delaware, 69 percent said that when results were positive for fentanyl, they subsequently took risk-reduction measures; in Baltimore, just 23 percent did so.

Certainly acceptance of the strips has soared among casual drug users. This summer, Chicago officials urged people attending the Lollapalooza music festival to pick up free kits from the city. The nonprofit TACO (Team Awareness Combating Overdose) has given away thousands of strips to students on at least a dozen college campuses. Many emergency rooms provide strips to overdose patients upon discharge.

Ms. Lopez said she had even persuaded some drug sellers to try the strips.“I’ve had drug dealers tell me, ‘I don’t have any fentanyl in my stuff!’” she said. “And I say, ‘Well, how do you know?’”

Regular use of strips by dealers could make a difference, said Corey S. Davis, who directs the Harm Reduction Legal Project at the Network for Public Health Law. “People are already there to buy heroin, so if a dealer can say, ‘Hey, I’ve tested it, and I’m actually selling you what you think you’re buying,’ that’s a good thing,” he said. “Dealers are making sure they’re not poisoning their customers with a much more dangerous drug.”

The divergent messaging on fentanyl test strips gets translated into inconsistent practices even within the same state. Kentucky considers them drug paraphernalia but gives decision-making authority to local health departments. So in cities like Lexington and Louisville, mobile units or clinics readily hand out the strips, said Jim Thacker, project director of Target4, an H.I.V.-prevention and harm-reduction program at the University of Kentucky. But in many rural counties, he said, police officers have detained program participants and confiscated the kits.

Mr. Thacker said that particularly in the Bible Belt, resistance to harm reduction springs from a stigma that still attaches to drug use.

“Addiction is not seen by a lot of people as an illness,” he said. “It is seen as a moral failure. I’ve heard multiple times that ‘the best way to solve the drug problem in Kentucky is to gather up all the drug users and lock them in a big space and supply all the drugs they could possibly want and let them all overdose and die.’ ”

Even where test strips are easily obtained, they have limitations. They measure the presence of fentanyl, but not its concentration. While many clinics, pharmacies and drug treatment programs provide them free, in locations where access is difficult or banned, they must be purchased online for about a dollar or two each, a cost that can add up quickly for a regular user.

The effectiveness of the testing, in which a small drug sample is dissolved in scarcely a capful of water into which a strip is then dipped, relies completely on the user’s compliance. That’s why outreach workers like Ms. Lopez try to engage users directly, clambering under bridges to find them and perusing parks near high schools.

The tests require even more diligence from people who buy counterfeit versions of pills like Xanax, OxyContin or Percocet through social media or street dealers. Cartels that press the pills salt them haphazardly with fentanyl filler. So while one pill might test negative, others could be contaminated. Each pill should be tested.

But such rigor is antithetical to young people looking to party, or to people who struggle with addiction, said Kevin Sabet who, with former congressman Patrick Kennedy, is a founder of the Foundation for Drug Policy Solutions.

“Addiction is chaotic and disturbing,” said Mr. Sabet, who thinks the strips’ utility is modest. “It hijacks the brain. So the idea that while you are in active addiction you are going to make a lot of rational choices with regard to your drugs sort of goes against the very notion of what addiction is.”

Ms. Lopez disagreed with that broad-brush view, saying she knows functioning heroin users who use the strips responsibly because they fear an inadvertent fentanyl overdose.

But she acknowledged that people who are deeply in addiction tend to reject the strips. “They want fentanyl,” she said, “because their goal is being high. Their lives have become so empty that they figure that even if they die in the pursuit of that goal, it’s worth it to them.”

So she looks for people who can be at least persuaded to carry strips for the sake of saving others. Sussing out who might be receptive is a subtle skill, a blend of observation, intuition and street-wise experience.

Ms. Lopez and her co-worker Stephanie Llivichuzhca walked along 149th Street toward the Hub, a Bronx commercial center dense with drug traffic. Clusters of men leaned against storefronts, casually thumbing wads of cash.

As Ms. Lopez approached, she offered icebreaker inducements. To men chatting outside a barbershop: “Papi! How y’all doing? Need some condoms?” (Throughout the day, every man, young or old, responded: “You got Magnums?”) Then she would pivot to her test-strip pitch.

A thin, worn-looking woman sat alone at a cafe table, staring vacantly. “How you doing, Mama?” Ms. Lopez called, pulling out a hygiene kit from her bag.

As she headed toward the bustling spoke of the Hub, a man plunged a needle in his arm. She swerved away. “This is crazy to me!” she sputtered angrily. “Before Covid I don’t remember people feeling comfortable enough to shoot up in front of everybody. The world has definitely changed for poor people. They were borderline desperate before, but now they’re full-on desperate. ”

By the end of the shift, the women had distributed about 20 fentanyl test kits in addition to hygiene kits, condoms and Narcan, which reverses overdoses. Their program, New York City Communities for Health, run by the Silver School of Social Work at N.Y.U., also distributes kits in other neighborhoods in the Bronx and Manhattan.

The late-afternoon sun ducked behind clouds, and a chill breeze kicked up. How would Ms. Lopez find recipients when the weather turned wintry?

She was not daunted. “We should try to get people while they’re waiting for the subway,” she said to Ms. Llivichuzhca. “We would totally rock it!”