
Radiation
Risk To Low Fluences of Alpha Particles May Be Greater Than We Thought
Center for Radiological Research, College of Physicians and Surgeons
and Environmental Health Sciences, School of Public Health, Columbia
University August 2001
This study provides clear evidence that a single alpha particle
can induce mutations and chromosome aberrations in cells that received
no direct radiation exposure to their DNA. These findings imply that
the target for radiation-induced genetic damage is larger than an
individual cell. The observation is important in formulating risk
assessment models because, for alpha particles, a cell cannot receive
a dose lower than a single traversal and these hit cells are a minority
population in lung tissue exposed to environmental radon.
The observation that irradiation of as few as 10% of a cell population
results in a mutagenic yield similar to that when all of the cells
in the population are hit indicates that low dose alpha particle
irradiation can induce a huge bystander mutagenic response in neighboring
cells not directly traversed by alpha particles. These results are
of considerable importance in reassessing the potential genotoxic
effect of low dose radiation and suggest that the assumption of direct
proportionality in radiation may significantly underestimate the
risk.