Sites with Special Exposure Cohort (SEC) Status:
- Iowa Ordnance Plant, 1949-1974 (Burlington, Iowa) (a/k/a Burlington Ordnance Plant; Iowa Army Ammunition Plant; Mason & Hanger; Silas Mason Co.)
- Joslyn Manufacturing and Supply Company, 1943-1947 (Ft. Wayne, IN)
- Kellex/Pierpont, 1943-1953 (Jersey City, New Jersey) (a/k/a Kellex Corp.; Vitro Corp of America)
- Lake Ontario Ordnance Works (LOOW), 1944-1953 (Niagara Falls, New York) (a/k/a Niagara Falls Storage Site (NFSS))
- Lawrence Berkeley National Laboratory, 1942-1961 (Berkeley, California) (a/k/a Lawrence Radiation Laboratory; LBL; Radiation Laboratory)
- Lawrence Livermore National Laboratory, 1950-1973 (Livermore, California) (a/k/a California Radiation Laboratory)
- Linde Ceramics Plant, 1942-1969 (Tonawanda, New York) (a/k/a Linde Air; Praxair; Tonawanda Laboratory)
- Los Alamos National Laboratory (LANL), 1943-1975 (Los Alamos, New Mexico) (a/k/a Los Alamos Scientific Laboratory)
- Mallinckrodt Chemical Company, Destrehan Street Plant, 1942-1958 (St. Louis, Missouri) (a/k/a Mallinckrodt Chemical Works; MCW; St. Louis Downtown Site)
- Massachusetts Institute of Technology (MIT) – Hood Building only, 1946-1963 (Cambridge, Massachusetts) (a/k/a Hood Building)
- Medina Modification Center (formerly Medina Facility), 1958-1966 (San Antonio, Texas)
- Metallurgical Laboratory, 1942-1946 (Chicago, Illinois) (a/k/a Eckhardt Hall (+ West Stands, New Chem. Lab and Annex, Ryerson Physical Lab, Kent Chem. Lab); Met Lab)
- Metals and Controls Corp., 1952-1967 (Attleboro, Massachusetts) (a/k/a M & C; Texas Instruments; M&C Nuclear; Metals and Controls Nuclear Corp.)
- Monsanto Chemical Company, 1943-1949 (Dayton, Ohio) (a/k/a Dayton Project; Old Schoolhouse; Runnymeade Playhouse; Units I, III and IV)
- Mound Plant, 1949-1980 (Miamisburg/Dayton, Ohio) (a/k/a Dayton Project; Miamisburg Closure Project; Miamisburg Environmental Management Project (MEMP); Monsanto Research Corp.; MOUND; Mound Site; Units I, III and IV)