The company Exide owns a battery recycling plant in East Los Angeles that’s been closed for years. But the plant spewed lead, arsenic and other carcinogens known to cause serious health problems — such as increased risk of cancer, breathing diseases, and learning disabilities — into nearby communities for decades. But things have become more complicated in recent weeks after a federal judge approved Exide’s bankruptcy plan, raising questions about how the state will pay for the continued cleanup of some 6,000 homes and properties.