A new study suggesting Tasers pose little risk to those receiving the shocks has sparked further debate over their safety.
The research, which was presented at the American College of Emergency Physicians' Research forum in Seattle, arrives amid a number of high-profile reports of police incidents involving Tasers in recent weeks.
Lead study investigator Dr. William Bozeman, an emergency medicine specialist at Wake Forest University in Winston-Salem, N.C., emphasizes that, when used in appropriate situations, Tasers are much better than alternative means.
"This is the first real-world application study regarding the injury incurred by these weapons, because previous studies have encompassed either human volunteers or animals," he says.
In his research of 597 past situations in which Tasers were used by police officers, Bozeman found that serious injuries were rare, occurring only 0.3 percent of the time.
Bozeman adds that he was anticipating a higher level of injury -- injuries that might require hospital admission or incur long-term disability.
Dr. Gary Vilke, professor of clinical medicine at the University of California at San Diego agrees with the findings.
"Research with police officers shows only minor injuries, such as those related to muscle contractions, no electrical injuries and one vertebral injury," he says. "I do not see any future problems."
But Dr. Corey Slovis, professor and chairman of emergency medicine at Vanderbilt University, says other recent research suggests that the weapons may be dangerous for some.
"I think that Tasers in normal subjects are safe," he says, "but I am concerned that emerging evidence may show that they may change the underlying heart rhythm of individuals who do not have a normal conduction system -- such as those using cocaine, those who are dehydrated, agitated, hypoxic or those taking anti-psychotics."
While Slovis says he once concurred with the conclusions presented in the current research regarding Taser safety, he now harbors some concerns, many of which stem from recent research on pigs.
In the research Slovis cites, the heart activity of the pigs was studied as they were being zapped with a Taser. What this study showed was that the heart rates of the animals jumped to more than 130 beats per minute at the time they were shocked -- a finding that leads Slovis to wonder whether the same kind of dangerous, racing rhythm occurs in human hearts as well.
"Tasers save lives, but Tasers are not perfectly safe," he says. "A Taser should not be used unless force is absolutely necessary. I am no longer convinced that Tasers are blameless."
However, Dr. Michael Lutes, assistant professor of emergency medicine at the Medical College of Wisconsin, notes that the pig study "did not tell much about the safety of the device."
He adds that law enforcement officers, before they are authorized to use the device on other people must endure a Taser shock themselves. Despite this requirement, no adverse effects have yet been reported by any of these officers.
But Slovis says that the ability of police officers in prime health to endure a Taser shock would not necessarily represent that of the people most likely to receive such a shock -- many of whom may have systems weakened by drugs, agitation or other factors.