Docs, what's causing brain tumours in children?

We don't know: The only known cause for brain tumors is ionizing radiation (atomic bombs, radiation treatment for cancer). A few genetic syndromes raise the risk of brain tumors (neurofibromatosis types 1 ; 2, von hippel-lindau syndrome, li-fraumeni syndrome, turcot syndrome). There's not enough data to show that radiowaves (cellphones) or electromagnetic waves (power lines) cause brain tumors in anyone.