The phrase “leading causes of death” might bring to mind cancer, heart disease, suicide and drug overdose. But new research published this month in the Proceedings of the National Academy of Sciences finds that young American men are at a surprisingly high risk of being killed by a police officer.

Among men of all races, ages 25 to 29, police killings are the sixth-leading cause of death, according to a study led by Frank Edwards of Rutgers University, with a total annual mortality risk of 1.8 deaths per 100,000 people. Accidental death, a category that includes automotive accidents and drug overdoses, was the biggest cause at 76.6 deaths per 100,000, and followed by suicide (26.7), other homicides (22.0), heart disease (7.0), and cancer (6.3).

The data used in this study do not differentiate between police killings that were later determined to be justified and those that were not. FBI data, which is widely acknowledged to be incomplete, shows that 400 to 500 homicides each year are determined to be justified, which is defined as “the killing of a felon by a law enforcement officer in the line of duty.” Those deaths represent about half of the roughly 1,000 annual police killings that independent tallies, including those by The Washington Post and The Guardian, have found.

For a black man, the risk of being killed by a police officer is about 2.5 times higher than that of a white man. “Our models predict that about 1 in 1,000 black men and boys will be killed by police over the life course,” the authors write.

In the 20 to 24 age group, black men represent nearly 2% of such deaths, compared with 0.5% for whites. A 40-year-old black man has about the same risk of being killed by a police officer as a 20-year-old white man.

Because no reliable federal data exist for police killings, the authors turned to the data compiled by Fatal Encounters, a project that uses news reports, public records requests and crowdsourced information to tally officer-involved fatalities. The authors note that Fatal Encounters was “endorsed as a sound source of data” by the federal Bureau of Justice Statistics in a 2016 report, but they warn that the data likely undercount the number of officer-involved killings.

Police killings are far more common in the United States than in other advanced democracies. That’s partly because the U.S. has a much higher homicide rate — “25.2 times higher” — than economically similar countries, according to a 2016 study. One of the prime drivers of that difference, research shows, is the nation’s high rate of gun ownership: Americans make up 4% of the global population but own nearly half the guns in the world.

The nation’s high rates of violence and gun ownership make many police fearful for their lives, research shows.

Data compiled by the National Law Enforcement Officers Memorial Fund show that, in recent years, 100 to 200 officers are killed annually in the line of duty. And other research shows that police are more likely to be killed in the line of duty in states with more permissive gun laws.

Officers can respond to the threat of violence by using lethal force of their own: More than half the 544 people shot and killed by police to date in 2019 were found to be carrying firearms, according to data compiled by The Washington Post.