z ard ous ▁he ating ▁under ▁conf in ement ▁cannot ▁be ▁ex cluded ▁in ▁the ▁industrial ▁use ▁of ▁mus k ▁x yl ene , ▁as ▁opposed ▁to ▁its ▁transport , ▁and ▁so ▁it ▁is ▁necessary ▁to ▁warn ▁potential ▁users ▁of ▁the ▁risk . ▁ ▁Car cin ogen icity ▁ ▁Mus k ▁x yl ene ▁also ▁demonstr ates ▁some ▁of ▁the ▁problems ▁of ▁class ifying ▁subst ances ▁as ▁car cin og ens . ▁It ▁has ▁been ▁placed ▁into ▁Group   3 ▁(" not ▁class ifiable ▁as ▁to ▁their ▁car cin ogen icity ▁to ▁humans ") ▁by ▁the ▁International ▁Agency ▁for ▁Research ▁on ▁Can cer ▁( I AR C ), ▁and ▁is ▁class ified ▁in ▁the ▁European ▁Union ▁as ▁category   3 ▁car cin ogen ▁(" c ause ▁concern ▁for ▁man ▁ow ing ▁to ▁possible ▁car cin ogen ic ▁effects ▁but ▁in ▁respect ▁of ▁which ▁the ▁available ▁information ▁is ▁not ▁ade qu ate ▁for ▁making ▁a ▁satisf actory ▁assess ment ") ▁under ▁the ▁D anger ous ▁Sub st ances ▁Direct ive ▁and ▁a ▁category   2 ▁car cin ogen ▁(" s us pected ▁human ▁car cin ogen ") ▁under ▁the ▁C LP ▁Reg ulation . ▁ ▁These ▁class ifications ▁are ▁based ▁mainly ▁on ▁a ▁single ▁study ▁of ▁or al ▁expos ure ▁to ▁mus k ▁x yl ene ▁in ▁B 6 C 3 F 1 - stra in ▁m ice . ▁The ▁m ice ▁showed ▁a ▁highly ▁significant ▁increase ▁in ▁li ver ▁ad en omas ▁and ▁car cin omas ▁at ▁median ▁di et ary ▁int akes