While the latest figures from the National Highway Traffic Safety Administration (NHTSA) seem to indicate that speeding and drunk driving are the culprits for a recent uptick in traffic fatalities, a Bloomberg article suggests that federal regulators are underestimating the impact of smartphone use on the numbers.

“Safety regulators and law enforcement officials certainly understand the danger of taking – or making – a phone call while operating a piece of heavy machinery,” Kyle Stock, Lance Lambert and David Ingold explain in the Bloomberg article. “They still, however, have no idea just how dangerous it is, because the data just isn’t easily obtained. And as mobile phone traffic continues to shift away from simple voice calls and texts to encrypted social networks, officials increasingly have less of a clue than ever before.”

Still, the authors assert that a deeper dive into the fatality data points to the conclusion that “mobile phones are far deadlier than NHTSA spreadsheets suggest.”

Aside from the fact that an estimated 81 percent of Americans now own a smartphone, several NHTSA data points offer clues: In 2016, motorcyclist, pedestrian and bicyclist deaths were up. “All of whom are easier to miss from the driver’s seat than, say, a 4,000-pound SUV – especially if you’re glancing up from your phone rather than concentrating on the road,” the authors add.

For more, read “Smartphones Are Killing Americans, But Nobody’s Counting.”