Some COLORED inks contained mercury,cadmium and lead.That was from years ago.That was why there was warnings against using colored printed papers for starting cooking fires.also this could leave toxic deposits in fireplace chimneys.
for those interested in the history of paper shredders and paper shredding-started about WW2.I can't get the link to work-try www. papershredders info.com They mentioned paper shredders(strip cut) came about in WW2 and crosscut about 1959.The "level 6" machines came about after the Watergate incident.