Chelsea Shover, PhD,

Epidemiologist & Health Services Researcher, the University of California Los Angeles

We sat down with Chelsea Shover, PhD, to talk about her amazing work on substance use and drug checking using the FTIR (Fourier-Transform Infrared Spectrometer), which is a resource provided through the UCLA AIDS Institute and the UCLA-CDU CFAR.


“I’m an Assistant Professor in the School of Medicine here at UCLA. I did my training in epidemiology here at the School of Public Health. And that’s when I first started working in HIV-related research in grad school before I did a postdoc, and now I’m on the faculty. I’ve really gotten into the substance use side of things while always keeping that connection with the intersection of substance use and infectious diseases.

I do a couple of different kinds of work. I do a lot of data science related to predicting and preventing overdose. I also conduct community-based work. I’ve done that around COVID. I worked for a few years as an epidemiology assistant during grad school at the Los Angeles LGBT Center. Now I am focusing on community-based work that involves using the FTIR to analyze illicit drugs and testing for main ingredients and potential contaminants.

Chelsea Shover


What got me interested in substance use was that it’s always been something that’s compelling to me. Like many of us, I had friends and family who struggled with substance use disorders. I’ve seen how people who use drugs often receive worse medical care and worse care from social services. I wanted to focus on an issue that is highly stigmatized, but that also has very good treatments and good prevention/harm reduction initiatives. This is a very big problem, but there are a lot of solutions that can make people’s lives better. That was my motivation for it.

In Los Angeles, where I do most of my work, we’ve always had a lot of methamphetamine-related deaths compared to other parts of the country. But now, half of those deaths also involved fentanyl. And there is a tremendous overlap there. This is one of the biggest problems we have to tackle right now in public health.


The resource that I’ve used with the CFAR has been the FTIR which was donated by the James B Pendleton foundation with an equipment grant. It’s a very expensive piece of technology, it’s not something I would’ve been able to buy on my own. It has been great to access and use it.

One of the things that I was interested in when I heard that the UCLA AIDS Institute was considering purchasing one for use by CFAR Investigators, was the potential to use it for community-based drug checking. Working with Pamina Gorbach, DrPH, MHSc, Steve Shoptaw, PhD, and Gigi Simmons, MD, of the Translational Research on Substance Use SWG leadership, I was able to assemble a team to roll out community-based drug checking. Drug checking basically means that people have, usually an illicit drug, or pill that they got through some type of social media interaction like Snapchat, but they don’t really know what it is. They bring it and you take a very small, grain of rice-sized sample and you run the FTIR on it. It generates spectra that are unique to the main compounds and allows you to find out things that can be detected in them. This is important, because if you detect something that someone wasn’t expecting that’s a really good place to provide education and help someone make an informed decision to provide harm reduction.

For example, if you had a sample that the person thinks is going to be cocaine but it’s actually fentanyl, they might decide not to use it. They might decide to use it only with other people or with naloxone on hand. It really depends on the individual. At the time, that was not a service that existed in Los Angeles. The kind of drug checking we had was just fentanyl test strips, which are very helpful if you don’t want to use fentanyl. But only if you use it correctly. Those test strips are cheap and easy to use once you know how. But they only tell you one thing: yes there’s fentanyl or no there’s not. They don’t tell you what else the sample might contain. So that’s limited when people want to know about the presence of other substances.

I think drug checking is very promising as something that can be offered as a wanted service that also provides the natural opportunity for people to engage in other kinds of services. It’s compelling to think about in Los Angeles, that we can offer it in places where we will reach people who might also not be engaged in HIV prevention and care, Hep C prevention and care, or housing services. If we’re able to say, hey we have this thing that is cutting edge technology and very fast. It only takes about a minute for it to analyze the results and five minutes to interpret them. You’re able to tell someone, hey the sample you brought contains methamphetamine and XYZ. That’s a good opening for other conversations about other kinds of services people might need because you’re establishing that base of trust and respect. Like, “oh we know you want this, and now that you’re here and we’re having this dialogue, is there anything else we can help you with?” I’m excited about the FTIR for those reasons. This is a clear mission of the Translational Research on Substance Use SWG and the Community Engagement and Clinical Informatics Core.

Dr. Shover’s research staff, Ruby Romero, left, and Caitlin Molina are the lead technicians using the FTIR for community-based drug checking.


When it arrived in the fall, I put together a training1 where we invited UCLA students, faculty, and community partners who were all interested and we did a two-day training program that included: 1) How to use the FTIR, 2) what are its strengths, and limitations and 3) what else do you need to do to implement the use of the FITR? I think that was a nice opportunity to engage with a lot of different groups such as the SF AIDS Foundation, attendees from UCLA Schools of Medicine and Public Health, CSULB, Community Health Project Los Angeles, LA County Dept of Health Services, Department of Veterans Affairs, and more. And that’s something we continue to do as we prepare to roll out community-facing programs through the SWG and Community Engagement and Clinical Informatics Core. That two-day training we had was also building on a year or so of active engagement in the broader drug-checking scientific community.

We first had the in-person training with the lead technician from San Francisco’s community-based drug checking. We then spent another six weeks doing more intensive practice, where the two main technicians and I would run samples and as needed would get feedback on our interpretation from the broader scientific drug-checking community. As we’re rolling out, now that we’ve gotten a solid understanding, we’re also training other people. In order to scale the number of people who can perform the testing, we do this via supervised field-based learning. There was a lot of front-end investment in terms of time and money. But now that we know how to use the instrument, it may be something that we may be able to help other researchers with.


I first just want to note that It’s a pre-print study, it has not been peer-reviewed. It’s at a journal now, undergoing peer review.

The question “Are pharmacies in Mexico selling counterfeit pills that contain fentanyl” came about because of my colleagues who had been doing ethnographic2 research in Mexico for many years. They started hearing through the course of their ethnographic work that participants thought that counterfeit pills were being sold in pharmacies.

Once the FTIR arrived, we felt like we could actually investigate this. Fentanyl test strips are useful, but they can only go so far. We also knew that counterfeit Adderall and Xanax were showing up in the U.S. We decided that we were not just going to look for fentanyl, we were also going to look for those two because we know that those are pharmaceuticals that are often counterfeited. The FTIR allowed us to do those other tests as well.

We obtained samples from pharmacies in Northern Mexico3. Then we tested them with both the FTIR and test strips (fentanyl, benzo, meth, and amphetamine test strips). From that process, we were able to confirm that while a number of the oxycodone samples were actually oxycodone, some contained fentanyl. 4 But the really interesting thing that we were able to do with the FTIR that we couldn’t have done with test strips, was that we found three pills that contained heroin. That was the most surprising thing to me. Fentanyl in the U.S. has largely displaced heroin. It just seems like a ton of effort to get heroin and make it into a pressed pill that is then sold as oxycodone or something else. That was a big surprise to me. The issue for public health there is that if someone were to get that pill and they take a fentanyl test strip just to make sure, that would come back negative, but it actually is heroin. So that was a really unique contribution that we were able to make by having this extra technology.


When thinking about CFAR resources that others can use, the listserv for early-stage investigators is a great place to learn about funding opportunities. It seems like there is a lot that comes through there and that seems really helpful for early-stage investigators. I found the communication with CFAR staff to be very efficient, helpful, and fast, which is always great. In terms of finding which services are available and how you use them, I think that makes it a really good resource. A lot of my colleagues who are focused on solid HIV work have taken advantage of some of the other services. Because it’s part of a network of CFARs, it’s a way to connect with investigators at other universities. In my experience, it has been a nice community of researchers to be a part of.”

Article Footnotes


  1. They have trained about 35 people to date.
  2. Ethnography is a type of long-term qualitative research, where researchers immerse themselves in the environment they are studying, forming long-term relationships with research participants. It can include formal and informal interviews and making observations about evolving events. Researchers take copious notes about the social dynamics they are studying and record interviews with participant permission. Researchers at UCLA’s Center for Social Medicine use ethnography to study evolving public health issues in Mexico and around the world.
  3. All the samples were sold as single pills.
  4. The FTIR can only detect compounds that are present at 5% or more. That amount of fentanyl is still enough for someone who doesn’t have an opioid tolerance to have a fatal overdose, so following up with fentanyl test strips (which are much more sensitive and can detect very minuscule amounts) is important.