Tom Smith, chair of Taser International, says despite the risks, Tasers do help prevent death and injuries based on police statistics. (CBC)

The chair of Taser International defended his company's stun guns on Monday when he appeared at a public inquiry in Vancouver examining police use of the weapons.

"Are Tasers risk free? No they are not. They do incapacitate and cause you to fall to the ground," Tom Smith told the inquiry led by Justice Thomas Braidwood.

Despite the risks, Tasers do help prevent death and injuries, said Smith, pointing to statistics from a study done by Peel Regional Police in Ontario that found a 37 per cent reduction in officer injuries and 47 per cent reduction in suspect injuries and deaths over a two-year period after Tasers were introduced.

Smith also took aim at what he called the myths about Tasers, saying there are no studies that prove they lead to heart problems, such as ventricular fibrillation.

The inquiry also heard from Liberal MP Ujjal Dosanjh, who was B.C.'s attorney general in 2000 when Tasers were introduced to Canadian police in Victoria under a pilot program he approved.

Liberal MP Ujjal Dosanjh says he wasn't given accurate information when he was B.C. attorney general and approved a pilot program for Tasers nearly a decade ago. (CBC)

Dosanjh, now the federal Liberal critic for the public safety ministry, said the assurances he was given about the safety, research record and amount of use stun guns would get all proved to be misleading.

"In fact, what has happened has been contrary to all assurances I was given," he testified.

Dosanjh said he was assured in 2000 that the Taser was "absolutely safe," had been "thoroughly researched" and would only be used sparingly.

The politician said there has been significant "usage creep" and Tasers are now being used where they were never intended to be used.

The Braidwood Taser inquiry was called after the Oct. 14 death of Robert Dziekanski, a Polish immigrant who was shocked by a Taser used by RCMP officers at the Vancouver airport. Dziekanski's ordeal, caught on videotape by a civilian witness, unleashed international outrage.

Smith challenged the notion that his company has sponsored most of the research into the devices, saying Taser International has only sponsored about 20 per cent of the research done on the electronic stun guns.

Previously Smith has insisted publicly that Tasers have been tested on 600,000 police officers and more than 400,000 ordinary citizens like himself, and no serious health complications arose.

Smith himself was challenged by some members of the inquiry, who wanted to know why Tasers come with a warning that the devices can kill.

"Everything's on the table," Braidwood told CBC News when the inquiry began May 5. "It means it could be banned or very severely limited as to when they can be used."

Cardiologist called Tasers unsafe

Monday's testimony comes after a San Francisco cardiologist and electrophysiologist brought forward damning evidence against Tasers at the inquiry, testifying on Friday that the stun guns pose potentially fatal heart risks by inducing cardiac arrhythmia.

Dr. Zian Tseng said any normal, healthy person could die from a Taser jolt if the shock was given in the right area of the chest and during the vulnerable point in the beating of the heart. He said the number of jolts a person receives increases the likelihood he or she will suffer serious health problems.

He stressed the risk of death is far greater if there is adrenaline or illicit drugs coursing through the body, or if the person has a history of heart or other medical issues, and he said that more real-world studies are needed on the use of the weapon, instead of using healthy police officers to test the device.

Tseng said that when he started researching Tasers three years ago and made his findings public, he was contacted by Taser International officials, who asked him to reconsider the statements he was making to the media.

"They even offered to support [my] research, to give me grant funding," Tseng said, adding he declined the offer in order to remain independent.

With files from the Canadian Press