Many of the former nuclear facilities produced significant environmental damages during their years of activity, and since the 1990s have been Superfund sites of cleanup and environmental remediation. Hanford is currently the most contaminated nuclear site in the United States and is the focus of the nation's largest environmental cleanup. Radioactive materials are known to be leaking from Hanford into the environment. The Radiation Exposure Compensation Act of 1990 allows for U.S. citizens exposed to radiation or other health risks through the U.S. nuclear program to file for compensation and damages.