Guns play role in shorter life expectancy in the U.S.

The researchers reviewed an array of studies over the years. They estimated that homicide and suicide together account for about a quarter of the years of life lost for U.S. men compared to those in those peer countries. Homicide, they noted, is the second leading cause of death among adolescents and young adults aged 15-24. The large majority of those homicides involve firearms.

The researchers said there is little evidence that violent acts occur more frequently in the United States than elsewhere. It's the lethality of those attacks that stands out.

"One behavior that probably explains the excess lethality of violence and unintentional injuries in the United States is the widespread possession of firearms and the common practice of storing them (often unlocked) at home. The statistics are dramatic," the report said.

For example, the United States has the highest rate of firearm ownership among peer countries — 89 civilian-owned firearms for every 100 Americans, and the U.S. is home to about 35 to 50 percent of the world's civilian-owned firearms, the report noted.

Woolf said that researchers had expected that homicide would be an important factor in explaining the health disadvantage that existed in younger adults in the U.S., particularly among young men.

"The size of the health disadvantage was pretty stunning. The fact that our risk of death from homicide is seven times higher and from shootings 20 times higher is pretty dramatic, but I would add that was probably just as important to us was the extent of the health disadvantage in young Americans that had nothing to do with violent injuries."

Woolf cited the statistics regarding premature babies and the high prevalence of illness among teenagers as equally disturbing as the statistics on guns and violence.