In Washington state, six workers at the Hanford nuclear site have undergone medical evaluations for possible exposure to chemical vapors. In total, more than 30 workers are being evaluated for possible exposure to vapors resulting from radioactive waste from the U.S. nuclear weapons program, which is stored in underground tanks at the site. Last month it was revealed thousands of gallons of radioactive waste had leaked between two walls of one of the tanks, an incident a former worked called “catastrophic.”