Brad Harrison is a proud former NSW Waratah and president of one the largest junior rugby districts in Australia. But he won't be cheering on his 14-year-old son Luke in the Sydney Junior Rugby Union competition any longer – because he feels the sport has become "too dangerous".

"The landscape of junior rugby has changed significantly, children are maturing at different rates and what we are seeing is a huge discrepancy in the size of children between the ages of under 12 and under 14," said Mr Harrison who was a flanker for the Waratahs in the mid-nineties.

"It is a miracle it hasn't yet happened but, if the rules do not change, someone soon is going to suffer a catastrophic life-changing injury – and I did not want it to be my son. For that reason, I removed him from playing club rugby."

These are the views of a passionate rugby "tragic" who oversees the safety and welfare of more than 2000 children at Gordon Junior Rugby Union. But as a concerned parent now calling on the Australian Rugby Union (ARU) to introduce a safer, weight-for-age system, he is certainly not alone.

The ARU told Fairfax last week it is planning to respond with an "updated national policy" set to be introduced for the 2017 season.

While a spokesman refused to elaborate on how the strategy might work, he said a "panel of experts" had been assembled to review a "range of safety issues" associated with the junior game.

The panel are also analysing "existing research" and "international competition models" surrounding "weight and age" in grades under 19 and below.

In a letter to Sydney Junior Rugby Union last May, Mr Harrison spoke of the "increasing disparity" in the size and physical maturity of players, adding: "The most obvious concern is that we are breaching our duty of care to these young people due to an unacceptable safety risk."

He went on to cite current trends of "declining registrations" and an increasing number of matches being "forfeited" due to safety concerns. "If the unthinkable does occur ... then I fear for the future of our game," he said.

The ARU has previously refused to consider a weight category trial similar to the system adopted in New Zealand junior rugby which involves a preseason weigh-in and the possibility of teenagers playing in one of three possible age groups. It has, however, granted a discretionary policy that allows clubs to move players down from one level of age grade rugby to the level below.

Mr Harrison's son Luke is hoping he will end up as big as his father but for now, he's a 40-kilogram late developer who, until he was sidelined, was clashing with players his own age who weighed in excess of 100 kilograms.

"It didn't just bring a tear to my eye, I had tears rolling down my cheeks," said Mr Harrison of his "heartbreaking" decision to withdraw Luke from the Lindfield under-14s side.

Luke added: "I got the reasoning behind it because I was injured a fair bit last year. I got concussion twice. And there was a time before that when I ended up in the emergency ward at hospital. It can be pretty scary but like everyone my age, I just want to play the game and enjoy it."

Friend and under-14s teammate Angus Talbot is a fortnight younger than Luke but towers above him at 1.96 metres. He said there were often times on the field when he himself was concerned for smaller competitors. "With tackles, it does make you think twice," he said.

Another parent advocating the introduction of junior weight categories is Cecille Heath whose 13-year-old son Nicholas plays for both St Aloysius' College and Mosman Junior Rugby.

Mrs Heath, who was watching her son compete at the NSW Junior Rugby State Championships at Drummoyne yesterday, said: "He's fast, gutsy and very skilful but he is small for his age and sometimes, he is up against kids that are monstrous in size. It will take one innocent fall, one bad tackle, and we could be facing something extremely serious that changes our lives forever."

"Rugby at our school is dying," she added, referring to two teams that were reluctantly scrapped this year due to lack of interest. "Parents expect Australian Rugby to look after their children. Until it does so, those mums and dads will steer their kids into other sports and it will continue to die."

Another rugby parent cheering her son on yesterday, Julie, said she had "mixed feelings" about the concept. "I think moving kids up one year is fine but anything beyond that would be a completely different environment involving boys who are far more mentally developed."