"What's really driving the surge in overdoses is this increasingly poisoned drug supply," said Shannon Monnat, an associate professor of sociology at Syracuse University who researches geographic patterns in overdoses. "Nearly all of this increase is fentanyl contamination in some way. Heroin is contaminated. Cocaine is contaminated. Methamphetamine is contaminated.'' There's no current evidence that more Americans started using drugs last year, Monnat said. Rather, the increased deaths most likely were people who had already been struggling with addiction. Some have told her research team that suspensions of evictions and extended unemployment benefits left them with more money than usual. And they said "when I have money, I stock up on my (drug) supply," she said.