Billed as a "less lethal" alternative to firearms, Tasers have experienced a meteoric rise to infamy since their introduction to the US police force. This week, the BMJ publishes a new report regarding the impact of Tasers on cardiac health.
The new report highlights the danger Tasers pose to cardiac health.
Tasers are currently in use by more than 16,000 police forces in 107 countries.
Globally, Tasers have shocked people more than 1.35 million times (650,000 during arrests and stops and 700,000 during police training).
According to the main manufacturer - Taser International - one of their devices is deployed, on average, every 2 minutes.
The most common Taser is the X26, designed and manufactured by Taser International in Scottsdale, AZ. Since 1994, the company has sold more than 800,000 Taser weapons.
Tasers use compressed nitrogen to fire a pair of barbed probes into the skin of the target individual. They are capable of delivering 50,000 volts, causing intense pain and muscle contraction.
In addition to the main function, the Taser has a "drive-stun" mode. This allows the unit to be held against the skin to deliver the shock, which stimulates pain but none of the contractions.
A pull of the trigger on the gun-shaped device delivers 5 seconds of shock - and more if the trigger is held down.
Health concerns over Taser use
A recent increase in the number of Taser uses on mentally ill patients in care homes and hospitals has prompted the UK's home secretary, Teresa May, to order a review of how they are used on these types of situations.
Known risks of Tasers already include eye injuries, seizures, collapsed lung (pneumothorax), tonic-clonic seizures, seizures in people with epilepsy, skin burns, and muscle, joint, and tendon injuries, plus a short-lived decline in cognitive functioning.
The biggest safety concern is head injuries sustained from an unguarded fall.
Much of the research into the safety of Tasers has been conducted by the companies that manufacture them, and as such, their neutrality has been called into question.
In 2011, the US Department of Justice released a report on "less lethal" weapon use by US police forces:
"More than 200 Americans have died after being shocked by Tasers. Some were normal, healthy adults; others were chemically dependent or had heart disease or mental illness."
Can Tasers affect heart function?
Evidence of the Taser's ability to cause injury are well known, but one further area of concern has not yet been fully unpicked: can Tasers have a terminal effect on cardiac health?
There are concerns that a Taser attack might induce long-lasting arrhythmias caused by myocardial capture (when an external electrical stimulus changes the heart's natural rhythm).
Taser International, during trials with an experimental Taser model, did report one instance of cardiac capture. The company altered the design and, from then on, have not reported any further cases.
Ventricle fibrillation - where the ventricles of the heart quiver rather than fully contract - has never been picked up during any of Taser's official studies.
This lack of fibrillation and cardiac capture in Taser International's trials might be due, in part, to the use of healthy volunteers without heart problems or drug addictions of any kind. And, of course, in a real-life confrontation, heart rates are naturally elevated at baseline.
A recent report published in Circulation looked into eight cases of Taser use and concluded:
"The animal and clinical data clearly support the conclusion that a TASER X26 shock can produce ventricular fibrillation in humans"
One death of particular note was that of 17-year-old Darryl Turner in North Carolina in March 2008. He was made redundant from his supermarket job and refused to leave the store. When a police officer arrived, Turner was "tasered" for 37 seconds and died shortly after from ventricular fibrillation.
Taser has a long history of fighting and defeating lawsuits, but in the case of Turner's death, they lost. It was established that the company had not made sufficiently clear the dangers of longer shocks and shocks to the chest area.
Taser appealed the decision, but the appeals court panel overruled them, saying that the X26:
"...had been the subject of several academic studies. (Taser International) knew about these studies, in which researchers had concluded that the device posed a risk of ventricular fibrillation, a cause of cardiac arrest, especially when the electrical current from the Taser was applied near the subject's heart.
Nevertheless, (Taser International) failed to warn Taser users to avoid deploying the Taser's electrical current in proximity to the heart."
More recently, the UK reported their first instance of death resulting from Taser. Jordon Begley, a factory worker from Greater Manchester, died just 2 hours after the police used a Taser on him in 2013.
An inquest concluded that punches he received from police officers, along with the 9-second Taser blast were to blame for his consequent cardiac arrest.
There is a clear necessity for further study into the effects of Tasers on long-term cardiac health and its implications for use on those with existing medical conditions. The author of the BMJ report, Owen Dyer, told Medical News Today:
"In both Britain and the US, firings of Tasers by police are going up quite steeply every year, even though rules of engagement have not been relaxed. So either more people are resisting arrest each year, which seems unlikely, or we are seeing Taser mission creep.
At first, Tasers are an alternative where guns might have been used. Then they're an alternative where truncheons might have been used. Finally they're an alternative where words might have been used.
Tasers were not designed to be cattle prods, and they will never be lifesavers in that role."
MNT recently covered research into how stressful situations increase police officers' risk of cardiac death.
Written by Tim Newman