The "Secondhand" Risks of Gun Ownership

After decades of research, we know that exposure to secondhand smoke markedly increases a non-smoker’s chance of heart disease, cancer, and premature death. But to date we have known little about what it means to be exposed to ‘secondhand’ gun ownership. In other words, what risks or benefits do people who don’t own guns experience when they live with someone who does?

A study funded by the National Collaborative on Gun Violence Research found that people who live with a handgun owner (but don’t themselves own a gun) are nearly twice as likely to die by homicide than those living in gun-free homes. Women—who make up two-thirds of those who live with handgun owners—faced especially high chances of being fatally shot at home by their spouse or intimate partner.

The study was conducted by researchers from Stanford University, University of California at Davis, and Northeastern University. To estimate the effects of household exposure to handguns, the cohort study followed nearly 18 million non-gun owning California residents over a 12-year period, comparing homicide rates between those who lived with a gun owner and those who didn’t. The analyses controlled for gender, age, race, neighborhood, and the presence of long guns (rifles or shotguns) in homes. Higher homicide rates among people living with handgun owners were attributable largely to higher rates of gun deaths (rather than other types of homicide), and the risks were centered on homicides that occurred in the victim’s home. In other words, guns in the home were associated with an increase—not a decrease—in the risk of fatal assault.

“Our lack of understanding of the secondhand risks of something that more than a third of Americans are exposed to is an unacceptable gap in scientific knowledge,” said David Studdert, the principal author of the study. “While there is a growing body of evidence regarding the risks of firearm ownership, we know next to nothing about the risks faced by the tens of millions of Americans who live with gun owners, except that women account for most of that population.”

This exploration of the secondhand risk of exposure to gun ownership adds to the body of research funded by the collaborative. It follows the largest ever study on the association between suicide and gun ownership. Drawing on the same large sample of California residents, that study, published in June 2020 in the New England Journal of Medicine, revealed that gun owners were almost four times as likely to die by suicide than non-gun owners, even after controlling for gender, age, race and neighborhood.

Looking ahead, Studdert and his colleagues hope to update the California cohort (which ended in 2016) used in both studies so that they can examine how gun ownership patterns changed during the pandemic, and the incremental risks associated with the spike in gun purchasing over the past two years.

The National Collaborative on Gun Violence Research was established with seed funding from Arnold Ventures, and is supported by philanthropic donations. The collaborative is administered by the RAND Corporation under direction of a research advisory committee.

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