[ RadSafe ] Residential Radon and Risk of Lung Cancer: A Combined Analysis of 7 North American Case-Control Studies

[niton at mchsi.com]

I thought this may be of interest.  

Residential Radon and Risk of Lung Cancer: A Combined Analysis of 7 North 
American Case-Control Studies. 

Epidemiology. 16(2):137-145, March 2005.
Krewski, Daniel; Lubin, Jay H.; Zielinski, Jan M.;  Alavanja, Michael; Catalan, 
Vanessa S.; Field, R William ; Klotz, Judith B.; Letourneau, Ernest G.; Lynch, 
Charles F.; Lyon, Joseph I.; Sandler, Dale P.; Schoenberg, Janet B.; Steck, 
Daniel J.; Stolwijk, Jan A.; Weinberg, Clarice; Wilcox, Homer B.  
Abstract: 

Background: Underground miners exposed to high levels of radon have an excess 
risk of lung cancer. Residential exposure to radon is at much lower levels, and 
the risk of lung cancer with residential exposure is less clear. We conducted a 
systematic analysis of pooled data from all North American residential radon 
studies.

Methods: The pooling project included original data from 7 North American case-
control studies, all of which used long-term [alpha]-track detectors to assess 
residential radon concentrations. A total of 3662 cases and 4966 controls were 
retained for the analysis. We used conditional likelihood regression to 
estimate the excess risk of lung cancer.

Results: Odds ratios (ORs) for lung cancer increased with residential radon 
concentration. The estimated OR after exposure to radon at a concentration of 
100 Bq/m3 in the exposure time window 5 to 30 years before the index date was 
1.11 (95% confidence interval = 1.00-1.28). This estimate is compatible with 
the estimate of 1.12 (1.02-1.25) predicted by downward extrapolation of the 
miner data. There was no evidence of heterogeneity of radon effects across 
studies. There was no apparent heterogeneity in the association by sex, 
educational level, type of respondent (proxy or self), or cigarette smoking, 
although there was some evidence of a decreasing radon-associated lung cancer 
risk with age. Analyses restricted to subsets of the data with presumed more 
accurate radon dosimetry resulted in increased estimates of risk.

Conclusions: These results provide direct evidence of an association between 
residential radon and lung cancer risk, a finding predicted using miner data 
and consistent with results from animal and in vitro studies.

(C) 2005 Lippincott Williams & Wilkins, Inc. 
--------------------------
Radiat Prot Dosimetry. 2005 Jan 18 

  
THREE MILE ISLAND EPIDEMIOLOGIC RADIATION DOSE ASSESSMENT REVISITED: 25 YEARS 
AFTER THE ACCIDENT.

Field RW.

Department of Occupational and Environmental Health, Department of 
Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242.

Over the past 25 years, public health concerns following the Three Mile Island 
(TMI) accident prompted several epidemiologic investigations in the vicinity of 
TMI. One of these studies is ongoing. This commentary suggests that the major 
source of radiation exposure to the population has been ignored as a potential 
confounding factor or effect modifying factor in previous and ongoing TMI 
epidemiologic studies that explore whether or not TMI accidental plant 
radiation releases caused an increase in lung cancer in the community around 
TMI. The commentary also documents the observation that the counties around TMI 
have the highest regional radon potential in the United States and concludes 
that radon progeny exposure should be included as part of the overall radiation 
dose assessment in future studies of radiation-induced lung cancer resulting 
from the TMI accident.

PMID: 15657112 [PubMed - as supplied by publisher] 

Bill Field