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NRC Investigators Report Irradiation Not Accidental

By A. Arif Husain
Associate News Editor

The irradiation of post-doctoral researcher Yuqing Li was not an accident, according to a report by the Nuclear Regulatory Commission Wednesday.

Li, a researcher in the Center for Cancer Research for Professor of Biology Susumu Tonegawa, reported high radiation levels during a self-examination several days after working with a radioactive phosphorus isotope. The chemical is commonly used as a tracer in biological systems.

The incident occurred in August, and Li has since been monitored by the Medical Department and the Radiation Protection Office ["Researcher Exposed to Above-Normal Radiation Levels,"Oct. 20].

Federal investigators based their recent conclusion on the finding that no trace of radioactivity was detected in the lab, as would be expected after a spill or accidental mishandling, said John Glenn, the head of the incident team.

Officials suspect that phosphorus-32 may have been added maliciously to Li's food or drink, which was kept in a nearby room. It was also found that during off-hours, some areas of the lab in Building E17 "can be entered without a key and without a challenge," even though radioactive materials are stored there, Glenn said.

A separate NRC team will remain at the Institute to explore the issue of whether Li deliberately ingested the substance, or was poisoned by someone else.

The team will pass its findings on to the federal Justice Department for a decision on whether to prosecute, said NRC spokesman Diani Screnci.

Li was not present Wednesday when the NRC investigation team held its final hearing on campus.

Poisoning showed effects

The Radiation Protection Office found that Li's intake was no more than 579 microcuries of radioactive material, which is within the 600 microcurie acceptable limit for single-event and annual exposure to the chemical.

According to a News Office release earlier this month, Li was examined by the Medical Department and Environmental Medical Services several times, and "no health effects were noted."

However, the Washington Post reported yesterday that a source with detailed knowledge of the case said Li has complained of "vomiting and aches and pain."

Similarity prompted investigation

Investigators were motivated by the incident's close similarity with another phosphorus-32 poisoning reported at the National Institutes of Health in June. In both cases researchers were of Chinese descent, and ingested similar doses of the chemical.

The quantity of phosphorus Li ingested was below the level that would require reporting to the NRC. Glenn said the NRC decided to investigate, however, because of the similarity to the NIH case and the rarity of phosphorus-32 poisoning. He said the last previous ingestion occurred at Brown University in the early 1980s.

This article was compiled in part from wire service reports.