SAN FRANCISCO San Francisco may become the first city in the nation to charge shoppers for grocery bags. The city's environmental commission is expected to ask the mayor and board of supervisors Tuesday to consider a 17-cent-per-bag charge on paper and plastic grocery bags. Their goal is to reduce plastic bag pollution. Environmentalists say plastic bags jam machinery, pollute waterways and often end up in trees. Officials believe that the city spends five-point-two cents per bag annually for street litter pickup and one-point-four cents per bag for extra recycling costs. But grocers and bag manufacturers argue that many people already...