Domestic low-level exposure to radon gas is considered a major lung-cancer hazard, involving DNA damage to bronchial cells by alpha particles from radon progeny. At low radon levels, these cells are extremely rarely traversed by more than one alpha particle, whereas at higher levels, where cancer risks are assessable (in uranium miners), cells may experience multiple alpha traversals. Measuring the oncogenic effects of exactly one alpha particle without confounding effects of multiple traversals has not hitherto been feasible, resulting in uncertainty in low-dose radon risk estimates. Charged-particle microbeams irradiate individual cells with predefined exact numbers of particles; whilst previously too slow to assess small oncogenic risks, recent microbeam developments now permit irradiation of large cell numbers, allowing the first oncogenic risk measurements for exactly one alpha particle. Oncogenicity from exactly one alpha particle was significantly lower than for a Poisson-distributed mean of one alpha, implying that cells traversed by multiple alpha particles contribute most of the risk. If this applies generally, extrapolation from high-level radon risks (involving multiple alpha particles) overestimates low level (involving only single alpha particles) risks.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR011623-05
Application #
6346379
Study Section
Project Start
2000-09-01
Project End
2001-08-31
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
5
Fiscal Year
2000
Total Cost
$72,792
Indirect Cost
Name
Columbia University (N.Y.)
Department
Type
DUNS #
167204994
City
New York
State
NY
Country
United States
Zip Code
10032
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