SCHOOL authorities and parents have blamed a body image obsession among teenage boys for a steroids scandal that has rocked the elite St Joseph's Nudgee College.

Pressure to compete with imported sporting talent may also be driving students to steroids, which parents suspect are being bought through personal trainers at off-campus gyms.

Nudgee College yesterday confirmed two students were charged by police and expelled, and a third was cautioned after steroids were found on school grounds on Tuesday.

Principal Daryl Hanly sought to distance the bust from the school's renowned sporting program and described the questioning of multiple students as an "isolated incident".

"The college is satisfied on the basis of police advice that this incident has no links to the college sports program," Mr Hanly wrote in a statement.

"This incident, while serious, highlights the issues associated with body image for young men."

As the school appeared to close the door on further investigation, parents told of their concerns about access to steroids through personal trainers at outside gyms.

"To be honest we're all just gutted by it because they're just really nice kids who have made a very misguided attempt at self improvement," one Nudgee mother told The Courier-Mail.

"They're teenage boys. They've got Instagram and they've got Facebook and all the girls are commenting.

"It's a minefield and there's a million different motivations for them to do it."

An Australian supplement retailer, Serious Supplements, blamed sports stars involved in doping scandals for a growing acceptance of steroid use.

General manager Sami Chamoun - who condemned steroid use - believes Australia is one of the fastest-growing steroid markets in the world.

The steroids cost as much as $1000 a month but students from wealthy families can afford the pills and dodgy supplement shops, and personal trainers are able to supply them.