Story highlights Former football players are supporting new education initiative, Flag Football Under 14

"Please don't let your children play football until high school," one Hall of Fame player said

(CNN) Several former NFL players called Thursday for an end to tackle football for kids ages 13 and under.

Pro football Hall of Famers Nick Buoniconti and Harry Carson joined four-time Pro Bowl linebacker Phil Villapiano and researchers from Boston University to make the announcement. They're working with the Concussion Legacy Foundation to support a new parent education initiative, Flag Football Under 14, that pushes for no tackle football until the age of 14.

"I beg of you, all parents to please don't let your children play football until high school," said Buoniconti, 77, who has been diagnosed with dementia and probable chronic traumatic encephalopathy, a neurodegenerative disease.

"I made the mistake starting tackle football at 9 years old. Now, CTE has taken my life away. Youth tackle football is all risk with no reward."

Buoniconti helped the Miami Dolphins to three straight Super Bowl appearances, including two wins and an undefeated season in 1972, the only such season in all of NFL history. In November, he said he intended to donate his brain to research.