DENVER (CN) — Denver sued Philip Morris USA and several other tobacco companies in state court Friday seeking to recover the costs of cleaning up litter from nonbiodegradable cigarette filters discarded around the city. Philip Morris’ own website warns “there could be more cigarette butts than fish in the oceans” by the end of the decade. Modern cigarette filters are made from cellulose acetate, “a synthetic plastic polymer that does not biodegrade under ordinary environmental conditions." It wants the court to order the defendant tobacco companies to pay for the costs of cleaning up cigarette litter. Instead, the lawsuit seeks to recover the public costs the city alleges have been imposed on Denver because of those products," Schnieders said.