San Francisco's skyrocketing pension costs are untenable and both unions and politicians are to blame for abusing the system by negotiating extraordinary pension and retirement benefits without considering the unfair burden on future generations, according to a report issued Thursday. City officials acknowledged that San Francisco has some challenges. But Supervisor Sean Elsbernd, who has worked extensively on the issue, said the civil grand jury report grossly overstates the city's risk. He noted that voters, not politicians, have the ultimate say on the approval of retirement benefits. And because of that, he said, San Francisco is in a far better...