Wastewater-based epidemiology, the process of monitoring health indicators through sewage, has become a common way to track the spread of SARS-CoV-2, the virus that causes COVID. But before 2020 scientists were using the technology to follow a different public health threat: the opioid crisis. Just as sewage data can fill gaps in SARS-CoV-2 tracking, this public dumping ground can provide up-to-date, population-level information about which illicit drugs are being used in a community and whether prevention strategies are having an impact.
Thanks to the expansion of wastewater testing in the last four years, opioid monitoring efforts have gained new interest, culminating last fall in a program run by wastewater testing startup Biobot Analytics. Biobot, which has worked with national and local U.S. agencies on COVID tracking, recently announced that it is testing sewage samples from 70 sites across the U.S. for opioids and several other common drugs, as well as the opioid overdose treatment naloxone. This pilot program aims to demonstrate how researchers and health officials can use wastewater data to inform overdose prevention efforts, says Nora Volkow, director of the National Institute on Drug Abuse, which funded Biobot’s work.
“We need something that is sensitive and timely for detecting what drugs people are exposed to,” Volkow says. “Wastewater provides an incredible opportunity to do that.” The data are reported in close to real time and reflect everyone in a public sewershed. In contrast, other sources for tracking drug use often lag by months or years and are limited by how people engage with the health care system. For health officials, wastewater data may be valuable in planning naloxone distributions, outreach campaigns and harm-reduction efforts.
For scientists, opioid monitoring represents a new frontier in a field that’s gained significant attention and recruited many new researchers since 2020. As interest in COVID testing has waned—despite the fact that current levels of the virus are high, according to recent wastewater data—scientists have been “moving back to where we were in 2018 and ’19,” says Erin Driver, an environmental engineer at Arizona State University who started working on this testing before the pandemic began. “But now that people actually are aware of all this [research], I think we’re going to see more pushing into novel things,” she adds—for example, testing for other chemicals that serve as health indicators, such as stress hormones.
To identify patterns from sewage, scientists take samples from wastewater treatment plants, which process waste from a community’s homes and businesses. In Biobot’s drug monitoring program, company scientists work with treatment plant staff to collect samples using automated machines that pull in waste once an hour over the course of a day, says Kait Jimenez, lead scientist on Biobot’s chemistry team. Treatment plants then mail the samples to Biobot’s lab. “When we receive the samples, they’re typically really gross,” Jimenez says, because chunks of vegetables, bugs and other items people have flushed down their drains can be mixed in with human waste.
In the lab, Jimenez and her colleagues filter out the solid waste and then isolate the specific chemicals that they want to test from the remaining liquid. After that, the samples are ready for an analytical chemistry technique called liquid chromatography-mass spectrometry. Driver describes the technique as akin to sifting through a bowl of Halloween candy: the liquid chromatography machine “separates the candy into various piles—M&Ms here, Starbursts here.” Then the mass spectrometry machine counts up the piles—or quantifies how much of each chemical is present based on its molecular signature.
Liquid chromatography-mass spectrometry machines are advanced candy-sorters, capable of looking for “hundreds, if not thousands” of different chemicals, Jimenez says. Biobot’s monitoring program tests each sample for five targets: the opioids fentanyl and xylazine (also known as “tranq”), the stimulants methamphetamine and cocaine, and the medication naloxone. Scientists look for both the drugs themselves and their metabolites—the chemical end products that people excrete after consuming the drugs—to track how consumption patterns may be changing over time. These end products tell scientists that people actually used the drugs as opposed to flushing them down the toilet, Jimenez explains.
Under Biobot’s current agreement with NIDA, sites in its program will continue to collect samples once a week through the end of August 2024, with the potential to extend the program if this pilot goes well. After scientists test and analyze the samples, they share the results with local public health agencies, where the data will add to existing systems for tracking substance abuse. Gale Burstein, commissioner of health in Erie County, New York—one county participating in the program—is looking forward to a data set that includes the entire community, not just statistics that are captured by the health system through overdose deaths or 911 calls, she says. Existing data sets only show “the tip of the iceberg” of overdoses and other health impacts, she says.
Burstein and her colleagues may use the results from Biobot’s program to inform outreach efforts, both for health care and emergency response workers and the public at large, she says. For example, if the data show increasing amounts of fentanyl in the county’s waste, Erie County officials may encourage people who use drugs to employ fentanyl test strips to check for the opioid’s presence or use the drugs “with a friend who has Narcan,” Burstein says, referring to over-the-counter doses of naloxone. Health officials who are participating in the program will also be able to see naloxone trends in wastewater, which may help them assess how much of the treatment people in the community are using, says Cameron Colby, Biobot’s program manager for this project.
Because this program is geared toward research, not public-health surveillance, Biobot won’t publish resulting data on a dashboard like the one on its popular COVID-tracking site, Colby says. These data are also more sensitive than SARS-CoV-2 data because they display people’s use of illicit substances; officials must carefully consider how to share the results. Neither Biobot nor NIDA has yet publicly shared a list of the 70 sites participating in monitoring. San Francisco’s public health department is one of a few that has advertised its participation in the wastewater program. Still, maintaining the anonymity of wastewater data is important, says Jeffrey Hom, director of population behavioral health at San Francisco’s public health agency. “We cannot trace the data back to one neighborhood, much less one household or an individual person,” he says.
While projects testing wastewater for high-risk drugs predate the pandemic, COVID monitoring helped public health officials understand its potential. The pandemic allowed wastewater to “prove its value of being able to understand the burden of an illness at a population level,” Hom says. The next step for scientists and health officials who monitor drug use, SARS-CoV-2 or other public health indicators, he says, is to determine, “How is it that we can best leverage wastewater testing, interpret the data and ultimately make it actionable?”