On February 7, 2000, the National Institute for Occupational Safety and Health (NIOSH) received a request from Teamsters Local 89 for a health hazard evaluation (HHE) at the South Plant of United Catalysts, Inc. (UCI), which is owned by Sud Chemie, in Louisville, Kentucky. The request stated that employees may be experiencing adverse health effects, such as cancer and respiratory problems, due to exposure to a variety of metals, including nickel and depleted uranium. On March 3, 2000, NIOSH investigators visited the South Plant for an opening conference and walk-through inspection. NIOSH investigators spoke to UCI's contract medical provider regarding annual medical surveillance. They also reviewed UCI documents: criteria for clearing employees for respirator use, cancer surveillance studies conducted by the University of Louisville (UL) for UCI, and the Occupational Safety and Health Administration (OSHA) Log and Summary of Occupational Injuries and Illnesses from 1998 and 1999. UCI air sampling data for the years 1998-2000 were reviewed, and a walk-through inspection in buildings 1 and 2, and MAC-3 was conducted. We found that nickel exposures are consistently above the NIOSH recommended exposure limit (REL) in blending and batch operations, kiln- and dryer-related operations, lab work, product finishing/screening/packaging, and cleanup/maintenance. Uranium exposures in MAC-3 are well documented for radiologic hazard, but no sampling is performed to assess the chemical hazard. Over 10% of air samples collected by UCI in MAC-3 show radioactivity levels in excess of the legal limit. Annual medical surveillance consists of very broad screening, not all of which is related to occupational exposures. Determination of worker's ability to wear a respirator is primarily determined by spirometry, and the results of the spirometry are conveyed to management. The ongoing UL cancer study has not found elevated rates of cancer among UCI employees. The level of respiratory protection for nickel catalyst bagging operations needs to be increased immediately until improved engineering controls lower exposures there. UCI should determine how uranium exposures in the MAC-3 area compared to exposure limits (REL, threshold limit value [TLV], and permissible exposure limit [PEL]) set to protect workers from chemical hazards. In communicating medical results to the workforce, UCI should distinguish between general medical screening and screening done specifically to evaluate potential occupational exposures at UCI. Spirometry results should not be interpreted as a strict criterion to determine whether a worker is able to wear a respirator, and results of any medical tests should remain confidential. Nickel exposures are consistently above the NIOSH REL in blending and batch operations, kiln- and dryer-related operations, lab work, product finishing/screening/packaging, and cleanup/maintenance. The level of respiratory protection for bagging operations should be modified immediately to full facepiece PAPRs/supplied air respirators. Uranium exposures in MAC-3 are well documented for radiologic hazard but should be determined to assess the chemical hazard there. Over 10% of air samples collected by UCI in MAC-3 show radioactivity levels in excess of the legal limit.