[ RadSafe ] Hormesis effect in a case-controlled indoor radon study

[Jim Otton]

RADSAFERS,

 

This is a forward of a study posted by Bill Field to the RADONPROFESSIONALS
LIST.

The results suggest a hormetic effect to exposures up to about 4 pCi/L (150
Bq/m3), then an enhanced effect at about 7 pCi/L (250 Bq/m3).

 

Jim Otton

U.S. Geological Survey

Uranium, radium, radon specialist

 

  _____  

From: International Web Resource for Radon Professionals
[mailto:RADONPROFESSIONALS at LIST.UIOWA.EDU] On Behalf Of Field, R W
Sent: Friday, February 15, 2008 1:12 AM
To: RADONPROFESSIONALS at LIST.UIOWA.EDU
Subject: [RADONPROFESSIONALS] Thompson et al .Radon Study

 

My guess is that there will likely be quite a few letters-to-the-editor
commenting on this recently published study (attached).

 

Thompson et al.

 

Abstract-A study of lung cancer risk from residential radon

exposure and its radioactive progeny was performed with 200

cases (58% male, 42% female) and 397 controls matched on

age and sex, all from the same health maintenance organization.

Emphasis was placed on accurate and extensive year-long

dosimetry with etch-track detectors in conjunction with careful

questioning about historic patterns of in-home mobility.

Conditional logistic regression was used to model the outcome

of cancer on radon exposure, while controlling for years of

residency, smoking, education, income, and years of job exposure

to known or potential carcinogens. Smoking was accounted

for by nine categories: never smokers, four categories

of current smokers, and four categories of former smokers.

Radon exposure was divided into six categories (model 1) with

break points at 25, 50, 75, 150, and 250 Bq m_3, the lowest

being the reference. Surprisingly, the adjusted odds ratios

(AORs) were, in order, 1.00, 0.53, 0.31, 0.47, 0.22, and 2.50

with the third category significantly below 1.0 (p < 0.05), and

the second, fourth, and fifth categories approaching statistical

significance (p < 0.1). An alternate analysis (model 2) using

natural cubic splines allowed calculating AORs as a continuous

function of radon exposure. That analysis produces AORs

that are substantially less than 1.0 with borderline statistical

significance (0.048 < p < 0.05) between approximately 85 and

123 Bq m_3. College-educated subjects in comparison to highschool

dropouts have a significant reduction in cancer risk after

controlling for smoking, years of residency, and job exposures

with AOR _ 0.30 (95% CI: 0.13, 0.69),

RADONPROFESSIONALS - http://list.uiowa.edu/archives/radonprofessionals.html
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