Mass shootings trigger accidental deaths

The surge in firearm sales that can follow a mass shooting may result in more deaths than the shooting itself, according to a new study.

It was already known that mass shootings could drive up gun sales, thanks to research led by David Studdert of Princeton University that found handgun sales in the US shot up after the Sandy Hook and San Bernardino mass shootings. Studdert put the effect down to heightened fear about personal safety and security.

A new analysis of the Sandy Hook killings, published in the journal Science, confirms the surge in firearm sales and also finds a spike in accidental deaths by gunshot.

The authors, health economists Phillip Levine and Robin McKnight, from Wellesley College and the National Bureau of Economic Research, Massachusetts, US, studied Google search data to estimate exposure to guns in the US after Sandy Hook.

They theorised that people who entered “buy gun” into a Google search were more likely to purchase a new firearm, and those who typed “clean gun” were more likely to bring an existing gun out of storage.

The researchers found the frequency of both searches spiked immediately after the shooting.

Those searches spiked again five days later when President Obama proposed tighter gun laws; there is some evidence the threat of imminent regulation spurs gun purchases by people hoping to beat the clampdown.

The researchers then estimated actual gun sales based on the number of background checks – mandatory for anyone buying a gun from a federally licensed dealer – conducted in the five months after the shooting. They found an additional 3 million guns were purchased during that period.

Credit: levine et al., science (2017)

These combined data, write the authors, “show that exposure to firearms increased substantially in the post–Sandy Hook window”.

The researchers then used the National Vital Statistics system, which records every death in the US, to estimate death rates from accidental shootings during that five-month window.

Their finding is sobering; an additional 60 people, 40 adults and 20 children, died as a result of accidental firearm discharge in the wake of the Sandy Hook tragedy.

In a further analysis, the researchers divided US states into those, post-Sandy Hook, that had an increase in gun sales either greater or less than 1000 per 100,000 head of population.

The highest child death rates from accidental firearm discharge, they find, were concentrated in states with the greatest increase in gun sales.

The authors go on to pre-empt concerns their data only show correlation and not cause.

“Unless it happened to be the case that something else occurred that caused an increase in accidental firearm deaths at exactly the same time as Sandy Hook and in those locations where the gun-exposure spikes were largest, our approach will have generated causal estimates,” they write.

In a related article, public policy researchers Philip Cook and John Donohue argue robust gun research is on the rise in the US, despite underfunding that traces back to the 1996 Dickey amendment, which limited federal funding of injury prevention research that promoted gun control.

They detail recent research suggesting the winding back of laws against a “right-to-carry” guns has increased gun violence.

They also welcome innovations such as California’s Armed and Prohibited Persons System, which retrieves guns from people no longer permitted to own them due, for example, to a criminal conviction. That program’s effectiveness is, however, still being evaluated.

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