In Discus when am I allowed to use Chalk?

I went to a Junior Olympic regional meet last year in Discus and before the throwing started they checked everyones hands for "Tape" so I was wondering if I am allowed to use Chalk or Talc cause I see pro's using it but they said were not allowed to use any tape. So I ended up using spit which worked ok. So I was trying to figure out if your allowed to use Chalk or not?