GENEVA — Over 180 countries have opened a U.N.-backed conference on waste and hazardous chemicals amid hopes it could produce a sweeping agreement toward minimizing generation of plastic waste, which has formed a gigantic mass of litter floating in the ocean.

Rolph Payet of the United Nations Environment Program says he hasn’t heard “any serious objections” among participants in the two-week Geneva conference starting Monday to a proposal issued last year by Norway, which also aims to improve management of plastic waste flows between countries.

If approved, the proposal would require 186 countries who have agreed to the Basel Convention on hazardous waste to take steps toward those goals.

Attendees are also expected to consider a ban on perfluorooctanoic acid, or PFOA, that has been blamed for increased cancer risks.

The Associated Press