At least 15 workers at a factory where X-ray machines and other medical devices are made were exposed to unacceptably high levels of radiation during the past five years, investigators said.
The discovery raised questions about how workers at the Mallinckrodt Inc. plant in Maryland Heights, Mo., have been handling radioactive materials and how they have been monitored for exposure.
The Nuclear Regulatory Commission (NRC) announced last month that it was investigating plant procedures after Mallinckrodt executives notified the agency of a worker''s high radiation exposure in March.
The worker''s error had exposed his left index finger and thumb to 2,000 rems of radiation -- 40 times the maximum exposure limit for fingers for an entire year.
"It''s one of the highest occupational radiation exposures I''ve heard of," said James Cameron, The NRC''s senior investigator for the region.
Further investigation has turned up 33 other instances of overexposure to plant employees since 1995, due to improper procedures that exposed workers'' fingers or thumbs to high radiation, the St. Louis Post-Dispatch reported yesterday.
According to preliminary documents from the NRC and Mallinckrodt, the cases discovered so far involve employees handling radioactive material without proper shielding.
Further, some of the exposures were overlooked for years because they were not detected by monitoring devices.
The NRC and state public health investigators will hold a public meeting June 23 to release their report.
This will mark the second time in three years that the commission has found serious enough safety problems at the company to warrant a public meeting.
The NRC will determine fines in a second phase that begins after the public meeting.
The plant, which manufactures medical imaging devices such as ultrasound and X-ray machines, is the largest materials licensee regulated by the NRC.
Nearly 300 people work in the facility; approximately 100 of them are radiation workers. Those workers exposed to higher than maximum allowable levels last year have been transferred to areas away from even small amounts of radiation, NRC officials said.
by Virginia Sutcliffe