Radon - recent articles supporting risk at residential exposures

["John Williams" <JohnWi@law.com>]

Radiat Prot Dosimetry 2001;97(1):69-73 



Biomarkers specific to densely-ionising (high LET) radiations.



Brenner DJ, Okladnikova N, Hande P, Burak L, Geard CR, Azizova T.



Center for Radiological Research, Columbia University 630 West 168th 

Street, New York, NY 10032, USA. djb3@columbia.edu



There have been several suggestions of biomarkers that are specific 

to high LET radiation. Such a biomarker could significantly increase 

the power of epidemiological studies of individuals exposed to 

densely-ionising radiations such as alpha particles (e.g. radon, 

plutonium workers, individuals exposed to depleted uranium) or 

neutrons (e.g. radiation workers, airline personnel. We discuss here 

a potentially powerful high LET biomarker (the H value) which is the 

ratio of induced inter-chromosomal aberrations to intra-arm 

aberrations. Both theoretical and experimental studies have suggested 

that this ratio should differ by a factor of about three between high 

LET radiation and any other likely clastogen, and will yield more 

discrimination than the previously suggested F value (ratio of inter-

chromosomal aberrations to intra-chromosomal inter-arm aberrations). 

Evidence of the long-term stability of such chromosomal biomarkers 

has also been generated. Because these stable intra-arm anld inter-

chromosomal aberrations are (1) frequent and (2) measurable at long 

times after exposure, this H value appears to be a practical 

biomarker of high LET exposure, and several in vitro studies have 

confirmed the approach for unstable aberrations. The approach is 

currently being tested in a population of Russian radiation workers 

exposed several decades ago to high- or low LET radiation.







CA Cancer J Clin 2001 Nov-Dec;51(6):337-44, 322; quiz 345-8   



Radon.



Frumkin H, Samet JM.



Department of Environmental and Occupational Health, Rollins School 

of Public Health, Emory University, Atlanta, GA, USA.



Residential and occupational exposure to radon is the second leading 

cause of lung cancer after cigarette smoking. As many as eight 

million homes in the US have elevated radon levels according to 

Environmental Protection Agency estimates. High exposure levels in 

homes are largely a result of radon-contaminated gas rising from the 

soil. This makes it an unusual indoor air pollutant in that it has a 

natural source. This study examines the synergism between smoking and 

radon, what levels are considered safe, and what to do to safeguard 

against overexposure to radon.

: Ann Oncol 2001 Oct;12(10):1341-51 Books, LinkOut  





Radon: a likely carcinogen at all exposures.



Darby S, Hill D, Doll R.



Clinical Trial Service Unit, University of Oxford, UK. 

sarah.darby@ctsu.ox.ac.uk



BACKGROUND: Radon is a well-established lung carcinogen that has been 

extensively studied. Very high concentrations can occur in some 

underground mines. Concentrations also tend to build up in homes. 

MATERIALS AND METHODS: Epidemiological studies of radon-exposed 

miners and of residential radon and lung cancer are reviewed. 

Quantitative estimates of the risk of lung cancer, based on the 

experience of the miners, are applied to residential radon exposures 

in the United Kingdom. Strategies for the prevention of lung cancer 

induced by residential radon are discussed. RESULTS: Estimates are 

uncertain, but residential radon is probably responsible for about 

2000 lung cancer deaths per year in the United Kingdom, or around 6% 

of the total, making it the second biggest cause after smoking. Over 

80% of the deaths are estimated to occur at ages less than 75 and 

over 80% in smokers or ex-smokers. Around 90% of radoninduced deaths 

in the United Kingdom probably occur as a result of exposures to 

radon concentrations below the currently recommended action level of 

200 Bq m(-3). CONCLUSIONS: Further work is needed to obtain more 

reliable estimates of the risk of lung cancer associated with 

residential radon and on the cost-effectiveness of various 

intervention strategies before the most appropriate policies can be 

developed for managing exposure to this natural carcinogen





Phys Med 2001;17 Suppl 1:157-60 Books 



The role of promotion in carcinogenesis from protracted high-LET 

exposure.



Curtis SB, Luebeck EG, Hazelton WD, Moolgavkar SH.



Fred Hutchinson Cancer Research Center, Seattle WA 98109, USA.



Recent analysis of epidemiological studies using the two-stage clonal 

expansion (TSCE) model has shown that radiation-induced promotion 

dominates radiation-induced initiation for protracted exposures to 

radon. This strong promotion effect (i.e. enhanced proliferation of 

already-initiated cells) causes a pronounced 'inverse dose-rate 

effect', but by a mechanism completely different from those usually 

discussed in this connection. This rather startling result is 

discussed along with implications to extended space missions that 

include a significant amount of high-LET radiation. It is suggested 

that the effect might be caused by a 'Bystander Effect' by which 

normal cells in the vicinity of initiated cells are hit by alpha 

particles and send out signals that modify the cell kinetics of the 

already-initiated clones.





Rev Environ Health 2001 Jul-Sep;16(3):151-67 Books 



A review of residential radon case-control epidemiologic studies 

performed in the United States.



Field RW.



College of Public Health, Department of Epidemiology University of 

Iowa, Iowa City, Iowa 52242, USA. bill-field@uiowa.edu



Lung cancer is the leading cause of cancer death in the United States 

for both men and women. Although most lung cancer deaths are 

attributable to tobacco usage, even secondary causes of lung cancer 

are important because of the magnitude of lung cancer incidence and 

its poor survival rate. This review summarizes the basic features and 

major findings from the published U.S. large-scale residential radon 

case-control studies performed in New Jersey, Iowa, and Missouri (two 

studies). The methodology from an unpublished study covering 

Connecticut, Utah, and Southern Idaho is also presented. Overall, the 

higher categorical risk estimates for these published studies 

produced a positive association between prolonged radon exposure and 

lung cancer. Two studies (Missouri-II and Iowa) that incorporated 

enhanced dose estimates produced the most compelling evidence 

suggesting an association between prolonged residential radon 

exposure and lung cancer. The prevailing evidence suggests that the 

statistically significant findings may be related to improved 

retrospective radon exposure estimates. The general findings from the 

U.S. studies, along with extrapolations from radon-exposed 

underground miners, support the conclusion that after cigarette 

smoking, prolonged residential radon exposure is the second leading 

cause of lung cancer in the general population.







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