BOSTON—Because both criminal violence and gun rights have become contentious political topics, research on the health and safety aspects of gun ownership in the US is barely funded. In fact, many have questioned whether it should be studied at all. But Northeastern University's Matthew Miller used a talk at the meeting of the American Association for the Advancement of Science to argue that there's an area where the data shows a clear link between gun access and public health and that this topic reveals some hints as to how to better manage safety.

The issue in focus is suicide.

While the focus on gun safety has been in terms of violent crimes, suicide is actually a larger problem. In 2015, it was the 10th leading cause of death, and half of the suicides occurred through the use of firearms. That's roughly 22,000 of them—4,000 more than were killed in all forms of homicide. This large difference has held steady for several decades.

While surveys indicate the mental distress that triggers suicide is similar in all states, the suicide rates vary dramatically. The primary driver of this? The state's gun ownership rate. States with high rates of gun ownership average nearly seven times the suicide rate as those with low gun ownership, while non-gun suicides show no real pattern among the states. This trend has been identified in 20 different independent studies. Overall, the risk of death through suicide is estimated to be three times higher if there's a gun in the house.

While the data is correlative, the strength of the correlation makes any other explanation unlikely, Miller argued. For some other factor to explain the data, it would have to be present in 80 percent of the houses where guns are present and only within 10 percent of the houses without guns. So far, alternative explanations have come up short. It isn't that gun owners are especially prone to suicide—studies have indicated that gun owners are no more likely to experience the sort of mental distress that triggers suicide attempts.

Instead, Miller suggested two things contributed to these findings. The first is that suicide is an impulsive act, and access to a means of suicide makes a big difference. In support of this, he showed statistics from survivors that indicate that 70 percent of them took less than an hour between making the decision to try their attempts. The second is that using a gun is highly effective. Suicide attempt rates don't vary by state, but attempts using firearms are fatal 90 percent of the time. Those using pills or cutting only result in death about five percent of the time.

If the data is so persuasive, why isn't anyone treating it as the public health issue it is? Miller detailed misconceptions about the issue at nearly every level. To begin with, the public doesn't realize the extent of the problem. Polling data indicates that the public thinks that the homicide rate is much larger than the suicide rate rather than the converse. Rather than viewing it as an impulsive act, the public views suicide as a commitment: as if once someone decides to do it, they'll find a way.

Miller illustrated this with a polling question about putting an effective, well-designed suicide barrier on the Golden Gate Bridge. Most respondents didn't think the barrier would make much difference, since people would just find alternative ways to kill themselves. Surprisingly, about half the physicians answered the same way—and they're the ones treating suicidal patients. So, it's not surprising that only about 20 percent of the physicians who have suicidal patients have ever talked about gun ownership with them.

All of that's unfortunate, because this is where public health data can actually help us target interventions. It turns out that 90 percent of the guns used in suicides were purchased more than two weeks before they were used, many much earlier than that. So, trying to intervene at the level of gun sales probably won't do much good. Hand guns and long guns are used with equal frequency, so targeting a class of weapons won't be effective, either. Instead, in keeping with the impulsive nature of the act, the way the gun is stored makes a big difference: Miller indicated there's data that either keeping the gun in locked storage or storing it unloaded can cut suicide risk by about two-thirds.

With more research, it might be possible to identify other factors that can influence access to guns by the most vulnerable. But Miller thinks it's going to take a cultural change to have these make a difference. The example he used was drunk driving; it didn't used to be common to set a designated driver or take people's keys away, but they're both now part of social norms. It might be time, he suggested, to start shifting the social norms on things like how guns are stored. Given that the number of drunk driving fatalities is now much lower than the number of suicides, it doesn't seem to be an unreasonable hope.

If you or someone you know is struggling with suicidal thoughts or ideation, please take advantage of the National Suicide Prevention Hotline at 1-800-273-8255 in the US, or the Samaritans at 08457 90 90 90 in the UK.