WASHINGTON -- The ongoing availability in Canada of an abuse-prone pharmaceutical may be having a spillover effect far beyond its borders.

A form of OxyContin that was banned in the United States last year is still showing up in distant corners of the country, according to data presented at a conference in San Diego.

The suspicion is that pills are getting in from Canada.

The claim comes as Canada weighs whether to follow the American lead in banning the older form of the opioid painkiller that's easier to crush in order to achieve an instant high.

There's pressure from the U.S. to ban the generic form of the drug and switch to the next-generation -- a tamper-resistant version produced exclusively by U.S. drug-maker Purdue Pharma under a new patent.

Purdue was one of the participants at the San Diego Bio-Pharma conference last month, where statistics about Canadian-style OxyContin were distributed.

A drug-abuse researcher said data supplied by users pointed to evidence of Canadian pills in 11 states.

They were reportedly purchased 39 times in various pockets of the country, with the most concentrated cluster centred in New Mexico and surrounding southwestern states. The information was culled from a crowdsourcing website, Street Rx, where users can plug in details about the price they've been charged for drugs.

In an interview, the researcher who presented the findings attempted to put the numbers in context.

He called it fascinating that the pills kept turning up in so many places far from the Canadian border, during the survey period that wrapped up last Dec. 31.

But he made it clear that the data points to a trickle of Canadian product, not a gusher.

"The U.S. is not being flooded by this product -- don't get me wrong," said Dr. Rick Dart, of the Researched Abuse, Diversion and Addiction-Related Surveillance group.

"But it's consistent... It's a continuing event. This isn't one suitcase (being smuggled in)."

The crowdsource site is run by Dart's group -- which, in turn, was launched by Purdue Pharma in 2001. But the RADARS group has since become part of the public health authority in Denver, now works with a variety of companies including Purdue, and swears off any conflict-of-interest on the issue.

Its research was presented just before the Canadian government announced a 60-day public consultation period on regulatory changes involving oxycodone, the opioid ingredient in OxyContin.

Canada has faced high-profile pressure on the issue.

Not only has the new U.S. customs boss, Gil Kerlikowske, pushed for changes, but the governors of six New England states sent Canadian ambassador Gary Doer a letter in April calling prescription drugs an "urgent and pressing matter of public health."

The U.S. Centers for Disease Control reported in 2011 that drug overdose death rates in the United States had more than tripled since 1990, to unprecedented levels. It said that in 2008, more than 36,000 people died from drug overdoses in the U.S., and most of those deaths were caused by prescription drugs.

Among the governors who wrote to Doer was Vermont's Peter Shumlin, who recently dedicated the entirety of his annual state-of-the-state speech to opiate abuse.

In an event at the White House last month, Shumlin described the devastation caused by drugs in his state. He blamed oxycodone for getting people hooked on opioids, leading many to make the transition to a cheap and potent alternative: heroin.

A federal study concluded in 2011 that, among all U.S. states, Vermont had the highest percentage of residents who had used illegal drugs in the previous month -- at 15.28 per cent. The rate was 9.2 per cent in next-door New York State.

But some people have called talk of a growing heroin epidemic overblown.

The same U.S. federal agency indicated in 2011 that the number of people who had used heroin in the past month across the country -- 0.1 per cent -- was identical to the 0.1 per cent of a decade earlier.

Meanwhile, lots of addictive opiate pharmaceuticals remain readily available in the U.S. -- including Zohydro, Vicodin, and even larger-sized OxyContin pills.

So why the new regulations, aside from protecting Purdue Pharma's exclusive new patent?

One opioid specialist says he's delighted by the switch.

"At least the bottle with the prescription doesn't have my name on it when they find the body of the college student who took pills and drank alcohol at the same time," said Gilbert Fanciullo of the Dartmouth-Hitchcock Medical Center, based in New Hampshire.

"It took a very popular, potentially lethal drug out of the hands of people who could get hurt by it. It may be just the first step to make all OxyContin tamper-resistant. I personally think all prescription opioids should be tamper-resistant -- period."