More than 70 doctors and academics are calling for a ban on tackling in rugby matches played in UK and Irish schools.
In an open letter to ministers, they say injuries from this “high-impact collision sport” can have lifelong consequences for children.
They argue two-thirds of injuries in youth rugby and most concussions are down to tackles and urge schools to move to touch and non-contact rugby.
Supporters say rugby builds character and other forms are less challenging.
The concerns have been raised as a seven-year programme headed by the Rugby Football Union is on target to introduce rugby to a million children in state schools across England.
The RFU’s programme, which began in 2012 and is running until 2019, has so far reached 400 schools, with 350 to follow.
‘Fractures and dislocations’
But, in their letter to ministers, chief medical officers and children’s commissioners in England, Scotland, Wales, Northern Ireland and the Republic of Ireland, doctors say the risks for players aged under 18 are high.
They say many secondary schools in the UK deliver contact rugby as a compulsory part of the physical education curriculum from the age of 11.
“The majority of all injuries occur during contact or collision, such as the tackle and the scrum,” the letter says.
“These injuries, which include fractures, ligamentous tears, dislocated shoulders, spinal injuries and head injuries can have short-term, lifelong and life-ending consequences for children.”
The letter says concussion is a common injury and repeat concussion is most likely in players with a history of having suffered it previously.
“A link has been found between repeat concussions and cognitive impairment and an association with depression, memory loss and diminished verbal abilities, as well as longer term problems,” it adds.
“Children take longer to recover to normal levels on measures of memory, reaction speed and post-concussive symptoms than adults.”
The experts say injuries from rugby can also “result in significant time loss from school”.
They say that under the UN Convention on the Rights of the Child, governments have a duty to inform children about risks of injury.
PE teacher’s view
Jonny Cross, a PE teacher at Congleton High School in Cheshire – where rugby is compulsory from the age of 11 – says the sport provides a challenge.
Mr Cross says children wear gum-shields and are taught how to maintain the proper posture in scrums to avoid injury, a technique known as “tower of power”.
“Contact rugby helps build character. They are putting their body on the line in a match. The risk factor is part of it.
“It’s not taking risks for the sake of it – the point is not to be tackled. But they are pitting their mind, body and will against the other side.
“They enjoy the contact element. There is a ‘boy factor’ – it’s partly about developing masculinity. They would be more likely to be bored by touch rugby.
“I would say that some students need it. It provides a challenge, where challenge is being taken out of everyday life.”
One of the signatories of the open letter is Prof Allyson Pollock, from Queen Mary University of London, who has long campaigned about the dangers of rugby.
“Children are being left exposed to serious and catastrophic risk of injury,” she said.
“As a signatory to the UN Convention on the Rights of the Child, the UK and Irish governments should ensure the safety of rugby, by removing the contact from the children’s game in schools.”
The RFU said it took player safety “extremely seriously” and it was currently undertaking a large-scale injury surveillance and prevention project in schools.
A spokeswoman added: “We believe that rugby is a fantastic sport for children with many physical and social benefits, which can include an increase in confidence, self-esteem and self-discipline, as well as getting enjoyable physical exercise while working as part of a team.
“Teachers frequently comment on notable off-pitch improvements when the sport is introduced in their schools.”
The Association for Physical Education said contact versions of the game should only be introduced and managed by “suitably experienced staff” following recognised guidelines.
“The wearing of personal protective equipment (mouth guards and head protectors where appropriate) is recommended at all times,” the association said.
“Parents should be aware of what sports are taught in the schools they choose to send their children to – if rugby is taught, then parents send their children to the school in the knowledge that they are likely to be asked to play rugby at some level.”