TUESDAY, Oct. 24, 2017 (HealthDay News) -- Gun shows held in Nevada are not subject to any regulations, and they take place in a state that features some of the least restrictive gun laws in the country.
But on the heels of the Oct. 1 shooting massacre in Las Vegas, a troubling new investigation reveals that when gun shows have been staged in Nevada, the neighboring state of California has seen gun-related injuries and fatalities jump by nearly 70 percent in communities that are an easy drive to the Nevada border.
What's more, the spike endures for at least two weeks after the show.
"We found that there were acute increases in firearm deaths and injuries in California following gun shows in Nevada, but not gun shows in California itself," explained study author Ellicott Matthay.
"We also found that this association for Nevada gun shows was driven mainly by increases in firearm deaths and injuries due to interpersonal violence, as opposed to self-harm or unintentional injuries," he added.
Matthay is a Ph.D. candidate and research data analyst at the University of California, Berkeley's School of Public Health.
The Las Vegas shooting was carried out by what appears to have been a lone gunman who fired into a crowd of outdoor concertgoers from his perch on the 32nd floor of the Mandalay Bay hotel. In the end, 58 people were killed, and 546 were injured, many seriously. To date, no clear motive has been determined.
The California researchers pointed out that roughly 4 percent to 9 percent of all U.S. gun sales take place at gun shows, of which about 4,000 take place every year in the United States.
Many states, such as Nevada, deem such sales to be private, unregulated transactions, and therefore do not require background checks on site. Other states, such as California, heavily regulate both firearms in general and gun show sales in particular (during which all gun sales require background checks).
To explore the potential impact of unregulated gun shows, the study team sifted through date and location information for Nevada-based and California-based gun shows held between 2005 and 2013. All the information had been published in a comprehensive gun trade magazine called the Big Show Journal.
In all, 275 Nevada-based gun shows were identified, most of which had been staged in either Las Vegas or Reno. In the same timeframe, California hosted 640 such shows.
California-based firearm violence was tallied based on state death records, emergency department records, inpatient hospital records and hospital discharge records.
The researchers said they determined that California saw no gun-violence spikes in areas adjacent to California-based gun shows.
But after focusing on 161 Nevada-based shows, the study authors concluded that whenever Nevada hosted gun shows, the gun-related injury rate in nearby regions of California rose. It went from just 0.67 per 100,000 people to 1.14 per 100,000 people.
The study was published in the Oct. 23 issue of the Annals of Internal Medicine.
While the findings are "not definitive," Matthay said, the investigation suggests that stricter gun show laws "may be effective in preventing short-term increases in firearm deaths and injuries following gun shows." In contrast, more lax regulations may undermine gun safety, even in neighboring jurisdictions that have strict laws on the books, she said.
"It is important to note that the California areas that are near Nevada gun shows are sparsely populated, so a 69 percent increase in the rate translates to about 30 additional deaths and injuries," Matthay added.
"However, there are thousands of gun shows in the United States each year, most of them in relatively unregulated states," she noted. "If we extended this study nationwide, it is possible that the number of deaths and injuries associated with gun shows would be far greater."
The National Rifle Association did not respond to a request by HealthDay for comment on the findings.
Dr. Frederick Rivara, co-author of an editorial that accompanied the study, suggested the findings serve as a cautionary tale.
"The important implications," he said, "are that gun shows without universal background checks on all sales can result in guns being sold to people who then go out and use these to shoot other people."
Rivara is a faculty member of the Harborview Injury Prevention and Research Center, and serves as vice chair of the department of pediatrics at the University of Washington in Seattle. He is also editor-in-chief of JAMA Pediatrics.
"Gun laws do matter and do work," Rivara said, "even in places where you can drive your car across a state border. We must work together as a country to reduce access to guns by people who are going to commit harm with them."
There's more on gun violence at the American Public Health Association.