, ▁T issue ▁Pap ers ▁Ltd . ▁became ▁the ▁international ▁distrib utor ▁of ▁Bun z l ▁& ▁B ia ch ' s ▁paper ▁and ▁pul p ▁products ▁and ▁as ▁a ▁result ▁changed ▁its ▁name ▁to ▁Bun z l ▁P ulp ▁& ▁P aper ▁Ltd . ▁in ▁ 1 9 5 2 . ▁ ▁International ▁expansion ▁followed ▁throughout ▁the ▁ 1 9 5 0 s : ▁a ▁filter ▁production ▁factory ▁was ▁opened ▁in ▁South ▁Africa , ▁while ▁a ▁separately - run ▁company ▁named ▁American ▁Fil tr ona ▁was ▁set ▁up ▁in ▁the ▁United ▁States ▁in ▁ 1 9 5 4 . ▁Use ▁of ▁cig aret te ▁filters ▁increased ▁marked ly ▁in ▁the ▁ 1 9 5 0 s ▁as ▁links ▁between ▁sm oking ▁and ▁cancer ▁were ▁established , ▁and ▁Bun z l ▁soon ▁became ▁the ▁exclusive ▁supp lier ▁to ▁both ▁Imperial ▁Tob acco ▁and ▁Gal la her ▁Group . ▁Between ▁ 1 9 5 6 ▁and ▁ 1 9 6 4 , ▁Bun z l ' s ▁production ▁of ▁filters ▁increased ▁by ▁a ▁factor ▁of ▁twelve . ▁▁ 1 9 5 7 ▁– ▁ 1 9 8 0 : ▁Public ▁listing ▁and ▁divers ification ▁ ▁The ▁company ▁flo ated ▁around ▁ 3 0 % ▁of ▁its ▁shares ▁on ▁the ▁London ▁Stock ▁Exchange ▁in ▁ 1 9 5 7 , ▁with ▁the ▁Bun z l ▁family ▁retain ing ▁a ▁majority ▁st ake ▁for ▁another ▁de cade . ▁As ▁the ▁growth ▁in ▁u pt ake ▁of ▁filter ▁c igare tt es ▁began ▁to ▁tail ▁off ▁at