San Francisco supervisors have unanimously approved a ban on plastic straws and takeout containers treated with fluorinated chemicals.

The vote Tuesday followed a ban on plastic straws and stirrers that took effect in Seattle this month. The San Francisco legislation requires a second vote next week.

The legislation also makes napkins and utensils with takeout or delivery available only on request unless there is a self-serve station.

Starting Jan. 1, 2020, food and drink vendors in San Francisco must use carryout containers and food wrappers that are free of fluorinated chemicals.

The chemicals ward against grease and water, but proponents of the ban say the chemicals are harmful and do not break down in compost.