Thomas B. Borak
Projects
Skin Cancer Project
Comparing the risks for skin cancer and lung cancer from 222Rn decay products. There has been a suggestion that ambient conditions in underground mines might cause cancers at sites
other than the lung. Specifically, it was suggested that radon daughters in the ambient air might be
responsible for an excess risk of skin cancer. This project determined the dose and risk to basal cells
in the epidermis from plate-out of Rn daughters on the skin as a function of Working Level Month (WLM).
This is then compared to the projected risk of lung cancer per WLM. Fig.1 is the depth dose distribution
for alpha particle emitters uniformly deposited on a surface. Fig.2 is the distribution of basal cells as
a function of depth below the surface of the skin. Click here
to view the figures.
Combining these results and with plate out characteristics of 218Po and 214Po and including attenuation
from moisture and dust on the surface of the skin, we obtain a result of 16 mSv/ WLM for the effective dose.
The lifetime risk of fatal skin cancer following whole body exposure to the skin is
2x10-4 /Sv [ICRP 60 p 139]. The risk from radon decay products deposited on the skim would be
approximately 3x10-6/WLM. The lifetime risk for lung cancer from inhalation of radon daughters is
2x10-4/WLM [ICRP 60 p 139]. From this dosimetric analysis, the risk of skin cancer is more than 60
times smaller that the risk of lung cancer for the same exposure to radon daughters.
Research Project 1 - Microdosimetry of high energy heavy particles.
This research, sponsored by NASA, is related to dosimetry of cosmic radiation during manned space
missions. We are measuring the response of tissue equivalent proportional counters (TEPC) to beams
of particles such as 56Fe, 18Si, 12C, 4He, and high energy neutrons that are produced at the NASA Space
Radiation Laboratory in Brookhaven National Laboratory and the Heavy Ion Medical Accelerator at the
National Institute of Radiological Sciences (NIRS) in Japan. This work is in collaboration with
physicists from the Lawrence Berkeley National Laboratory and NIRS.
Fig. 1 shows the arrangement used during a recent experiment at HIMAC.
Mailing Address
Environmental & Radiological Health Sciences
