This story was originally published by The Trace, a nonprofit newsroom covering gun violence in America. Sign up for newsletters from The Trace here.

Correction: An earlier version of this story by The Trace misrepresented the study’s findings by not including a per capita calculation. It has been updated to indicate that the firearm suicide rate in California actually increased by 6% for every 20 ghost guns recovered per 100,000 people.

People who attempt suicide, nine out of 10 times, will survive — if they don’t use a gun. But suicide attempts with a firearm are almost always fatal: nine in 10 attempts end in death. 

For years, researchers have been sounding the alarm on the deadly connection between firearms and suicide risk, emphasizing that the danger of suicide is also a matter of access. Now that research is going a step further, linking increases in firearm suicide to ghost guns, a type of unserialized firearm assembled from kits typically bought online.

Using data from The Trace’s Gun Violence Data Hub, researchers at New York University analyzed California’s gun recoveries in conjunction with data from the Centers for Disease Control and Prevention. The study found that for every 20 ghost guns recovered per 100,000 people, the firearm suicide rate increased by about 6% across the state.

The authors said the findings, published last month, are the first empirical evidence linking ghost gun recovery rates to firearm suicide rates, laying an initial groundwork for understanding the health risks associated with homemade guns.

“Ghost guns are not just a law enforcement problem, they are a public health problem,” Jemar Bather, a biostatistician at NYU and the study’s lead author, told The Trace via email. “[They] can be acquired without background checks or waiting periods, bypassing the very safeguards designed to create a pause between intent and action, which makes them particularly consequential for individuals seeking means for self-harm.” 

Although the findings showed an association between gun suicide and ghost gun recoveries, there was no statistical difference in homicides, which the authors said are epidemiologically distinct crimes that necessitate more research. 

So-called ghost guns are built from 3-D-printed and kit-built components sold online, and they are not serialized, making them extremely difficult to trace. They first began circulating about 15 years ago, particularly in California, where the study originated. Because of their easy assembly and relative affordability, the market for the weapons was booming by 2016, and between 2017 and 2021, the Bureau of Alcohol, Tobacco, Firearms, and Explosives recovered 37,000 of them; more than half were recovered in California.

Last year, the Supreme Court upheld the Biden administration’s restrictions, which mandated that manufacturers serialize their kits, required sellers to have a license, and enforced background checks. The regulations seemed to be slowing down the availability of ghost guns, as police are recovering fewer of them. 

“Practitioners and policymakers alike should consider strengthening ghost gun regulations as a component of comprehensive suicide prevention strategies,” said Bather.

To inform those policies, researchers said there needs to be improvements in effective and real-time data collection on firearm shootings and deaths, made especially difficult in the case of untraceable guns. Although California is known for a high volume of homemade firearm recoveries, it’s also one of the few states that publishes extensive law enforcement data that could help clarify the connections between availability, access, and gun suicide. 

“This is not data that is collected everywhere and is difficult data to get,” said Diana Silver, a professor of global health and health policy at NYU, and one of the study’s authors. “Although we can’t generalize from this study beyond California, it does give us some insight into the landscape of gun ownership and ghost guns.”

The study’s authors acknowledged that their findings are likely extreme undercounts, as they represent a single state, but that it’s important to understand them as associations rather than causes. Still, developing the field of ghost gun research is crucial to saving lives and determining effective, specific reduction strategies, they said.

“We don’t know why people are turning to ghost guns to commit self-harm,” said Silver. “Breaking down these things is really important in this research because they aren’t the same; there are different reasons that go into these tragedies.”

Bather, the study’s lead author, said the paper has the potential to serve as a template in an area that direly needs attention.  

“This study is part of a broader effort to bring rigorous, data-driven evidence to an understudied area of firearm violence,” he said. “Gun recoveries have surged nationally, and there is a real need to replicate this work in other states and at the national level.”