Blackening of surface of printable dvd-r

hi

I have a number of white surfaced dvd-r's that have developed black discoloration of the surface. Is this due to leakage of the black cd pen used to label the disc or could it be because they are in close proximity to the back of my crt tv and exposed to some sort of radiation?

Thanks
Sam

 

well i guess it must be something to do with the radiation released from the back of the tv since my other discs written with the same marker seem fine.

Lesson learned: Keep discs away from back of tv