DJs are not regulated by the music they play for a private event (weddiings, parties, birthdays, etc) But they are regulated by Occupational Safety and Health Administration for their equipment set up (including lighting, lasers and other special effects), electrical usage also the sound levels :
Amplifier, rock, 4-6' 120dB
Rock music peak 150dB
When we provide sound and stage we must aquire a permit (in Florida), the rig is inspected and one pet peeve of theirs, if any of our power cords do not have the manunfacturer's warning tag on them they are removed by the state municipality or OSHA if they are onsite.
OSHA did a sweep in Central Florida about two years ago because strobe lights set off an epileptic seizure in a young female that caused her to fall and she received a serious head injury. This was at a private youth function where the DJ was aware of the young ladies vulnerability but used the effect anyway. OSHA shut down the venue, until an investigation was completed consiquently the venue sued the DJ. Lawsuit was pending from the family of the young lady also citing an OSHA finding "the lighting effect was not used in the manner specified by the light manufacturer". (the DJ had no insurance.)
Sooo, Beiber's music may not harmful but the equipment it's playing thru can be.
Paul