Twice as many Americans commit suicide in states where most households have a gun than in states with low rates of gun ownership, according to a new study.

Several studies have linked gun ownership to the risk of suicide by firearm, according to Dr. Matthew Miller, the new study's lead author from the Harvard School of Public Health in Boston.

But some critics question whether people living in states where lots of residents own guns are inherently more suicidal than those who live in places where ownership is less common.

To address that critique, Miller and his colleagues gathered state-by-state data on gun ownership, suicide attempts and suicide deaths from a variety of sources, including the U.S. Centers for Disease Control and Prevention (CDC) and health surveys.

They compared the 16 states with the highest gun ownership rates to the six states with the lowest rates. Both of those groups included about 62 million people.

In the high gun ownership group, 51 percent of adults lived in a household with firearms, versus 15 percent of adults in the low gun ownership group.

There were about 7,300 firearm suicides in the states with the most guns - including Alabama, Montana and West Virginia - in 2008 to 2009, according to findings published in the American Journal of Epidemiology.

That compared to 1,700 suicides by gun in the low ownership states, such as Hawaii, Massachusetts and New York.

The number of non-gun suicides in the two sets of states was similar, at about 4,200 and 4,300, respectively. What's more, state-wide rates of suicide attempts did not differ based on levels of household gun ownership.

"Living in a home with a gun greatly increases the risk of suicide, and that increased risk is not because people who live in homes with guns or in areas where guns are more prevalent are more suicidal," Miller told Reuters Health.

"They're not. It's because when people make suicide attempts with guns, they're much more likely to die than when they make attempts with other commonly used methods."

The increased suicide risk associated with gun ownership is not a pro-gun or anti-gun issue, he added.

"We're not going to legislate our way out of suicide very easily, and that's not the goal," he said. "The goal is to help people realize that there is a risk."

The study confirms that people with guns at home are no more likely to attempt to kill themselves - but they are more likely to succeed because they are more likely to use a gun, Dr. Eric Fleegler, a pediatric emergency medicine doctor at Boston Children's Hospital and instructor at Harvard Medical School, said.

For example, about three percent of people who attempt suicide with drugs or cutting actually kill themselves, he said. But about 90 percent of attempts using a firearm are successful.

According to the CDC, about 12 in every 100,000 Americans committed suicide in 2010 - half of them with a gun.

"It is unlikely that we're going to take guns away per se, but we do need to make people understand the risks that are associated with this," said Fleegler, who studies firearms and public health but did not participate in the new research.

People with guns at home can take safety precautions, he told Reuters Health, such as storing the gun in a lockbox and keeping the gun and ammunition in separate places.

The researchers agreed, however, that there hasn't been much funding available to study whether such gun safety measures are effective for suicide prevention.

After the Sandy Hook Elementary School shootings in Newtown, Connecticut, Miller noted, President Barack Obama announced he would make $10 million available to fund research on firearms and public health.

Right now, he added, the CDC spends about $100,000 on firearms-related research, and the National Institutes of Health spends "almost nothing."

Given that firearms are the second-leading cause of death among people under age 40 after car crashes, Miller said, even if that $10 million was made available every year it would still be "woefully inadequate."