People like to drink and take drugs at big gatherings, and the great solar eclipse of 2017 was no exception. According to a new study in the journal Science of the Total Environment, the rare event was linked to a dramatic spike in drug use, which the researchers discovered while taking a close look at public sewage following the big event.

In the paper, published August 15, a team of researchers at Murray State University in Kentucky present evidence that drug use during the solar eclipse of 2017 as well as on the fourth of July, was significantly higher than during the rest of the year. The study’s authors presented their findings on Monday at the annual meeting of the American Chemical Society.

“We found that during the Independence Day holiday and the solar eclipse day, people consumed cocaine, methamphetamine, amphetamine, and cannabis in higher levels than on a typical day,” Bikram Subedi, Ph.D., an assistant professor of analytical chemistry at Murray State University and the paper’s corresponding author, tells Inverse. He and his colleagues also found that, while levels of cocaine consumption more or less matched what the researchers presumed, people used amphetamine and methamphetamine at two to four times the rate that researchers assumed.

Solar Eclipse #7
Yeah, but have you ever watched a solar eclipse ... on methamphetamine??

Because people are not eager to fill anyone — even nonjudgemental scientists — on the details of their drug use, researchers have had to get sneakier about tracking drug use patterns at the community level. They’ve done so by using wastewater to track trends in drug use and potentially even identify new drugs of abuse. The evidence presented in the new study shows that traditional methods of assessing drug use could be underestimating the true public health burden of illicit drugs.

In the study, the researchers set up equipment that automatically took a sample of wastewater every 15 minutes for 24 hours at two wastewater treatment plants in western Kentucky, resulting in a sample that gave them an average for the day. After bringing these samples back to the lab, the team compared samples collected on Independence Day and the day of the solar eclipse to samples collected on non-holiday weeks. Unsurprisingly, they found that people used a lot more drugs on the big days than on typical days. These drugs included cocaine, methamphetamine, amphetamine, methadone, morphine (which can also indicate the presence of heroin), and THC.

And even though the two communities are only 50 miles apart, the levels of drugs between them differed substantially. Subedi says that this preliminary evidence could hint at disparities in how the communities’ law enforcement officers approach illegal drug use.

Instead of testing individuals' urine, sewage epidemiology tests an entire community's.

The advantage of this method is that, even though it doesn’t capture data about individuals, it has the potential to be a lot more accurate than self-reporting methods.

“I’m not saying there’s no alternative methods,” says Subedi, referencing self-reporting surveys and hospital admissions data as two of the other main ways that public health researchers track the burden of drug use. “The problem with those techniques is that they typically underestimate consumption rates.”

Subedi hopes that sewage epidemiology will become a complementary tool for law enforcement and public health officials to get a more accurate picture of community-level drug use. He says that this technique can be useful in filling in blindspots in intelligence-gathering on the ways people are using drugs. What’s more, sewage epidemiology studies can be conducted nearly in real-time, taking days rather than months or years as other survey methods can take.

“We can see how much drugs were consumed yesterday in a community, and even today,” Subedi says.

One of the major drawbacks of sewage epidemiology, of course, is that it can only gather data on an entire community since the water being tested is in a central location. Subedi says eventually they may be able to go upstream to get a higher level of resolution on the scale of neighborhoods, but for now they’re limited to the water at a centralized wastewater treatment plant.