Tens of thousands of people received emails this week to warn them that wristbands distributed in the weeks preceding UJA Federation of Greater Toronto’s annual Walk with Israel may be hazardous.

The wristbands, or “slap bracelets,” are blue with white writing – “walkwithisrael.com” and the date of the walk, “05 26 13.”

The email said the item should be disposed of immediately and explained that if the plastic is torn away, “a sharp metal piece is exposed which can pose a danger.”

Steven Shulman, federation’s campaign director and counsel, that his organization only became aware of the issue May 27, after receiving a call from a concerned parent.

“As soon as we became aware that this could be a hazard… we wanted to make sure as quickly as possible that parents were aware of it,” Shulman said.

An estimated 16,000 people took part in the walk. More than $440,000 was raised to support UJA projects in Israel, according to the walk’s website.