NRC Finds Radiation Poisoning DeliberateBy Brett Altschul
The Nuclear Regulatory Commission has officially concluded that the ingestion of an unusually high level of radioactive phosphorous-32 by a Center for Cancer Research employee in August was "most likely" a deliberate act performed to poison him.
The conclusions, released in a 130-page report Friday, were drawn by the investigative team formed in November to determine if the poisoning of Post-doctoral Fellow Yuqing Li was intentional or accidental ["Radiation Ingestion Prompts Concerns," Nov. 3].
The report showed that Li ingested between 500 and 750 microcuries of P-32, perhaps slightly higher than MIT's estimate of 579 microcuries ["Researcher Exposed to Above Normal Radiation Levels," Oct. 20].
The legal annual exposure limit for personnel working with radioactive materials is 600 microcuries.
According to the report, the MIT Radiation Protection Office's final calculations were accurate, but the uncertainties involved prevent the calculation of an exact figure.
An NRC medical consultant stated that no symptoms or acute effects should result from an intake of this level.
Report decries inadequate security
The report criticized the Center for Cancer Research and the Radiation Protection Office for inadequate security in the lab and weak oversight of the storage and control of radionuclides.
In response to the incident, the Institute has tightened security and locked freezers containing radioactive materials, said Director of the News Office Kenneth D. Campbell in a recent article in The Boston Globe.
Although it concluded that MIT's security was lacking, the report found that the Radiation Protection Office's response to the poisoning was acceptable.
The NRC also found that its own failure to release information about similar poisonings might have contributed to this event.
The report confirmed the NRC's preliminary finding that the contamination had probably occurred as the result of a deliberate act by a knowledgeable person because there was no evidence of any other contamination in the lab where Li worked.
Investigators have not ruled out the possibility that the poisoning was accidental or self-inflicted, according to the Globe.
The NRC is also still unable to determine either the precise circumstances of the poisoning or a person who might be responsible.
The incident remains under investigation, and Li could not be reached for comment.