TORONTO -- Several T-shirts making fun of suicide once sold on Amazon.ca appear to no longer be available after a Toronto man's petition gained traction online.

Mark Henick, 28, launched a petition on Change.org that garnered nearly 50,000 online "signatures" in three days.

While some of the shirts appear to have been removed from the Canadian site, at least one of the shirts remains. And Henick said that more are still available on the website's French and U.K. counterparts.

The remaining shirt appears to encourage people to act on suicidal thoughts, which Henick said is unacceptable.

He said the shirts may seem like a joke, but they can trigger bad memories for people who've lost a family member or friend to suicide, or those who may have had suicidal thoughts in the past.

The shirts were sold by a private vendor on Amazon, and it's not immediately clear whether they were removed by that vendor or Amazon itself.

The online retailer has been quiet on the issue so far, which Henick said is disappointing.

He said that even though the company doesn't manufacture the shirts, it should be held accountable for making them available.

"It was probably an oversight," he said. "But Amazon holds the responsibility here, too. They're the ones with the massive, worldwide platform."

He said that ideally, he'd like to see Amazon donate money to a suicide prevention campaign.

Amazon did not respond to a request for comment.