Radiation Health Effects: Compiling the Data"
March 19, 1998
by Radiation, Science, and Health, Inc.,
Edited by J. Muckerheide
Emeritus Bernard L. Cohen, in the principle report in a series of papers
and analyses correlating 272,000 home radon measurements vs. lung cancer
by county in the US, considering and responding to all concerns
about alternative explanations and confounding factors, (1995) shows:
In age-adjusted lung cancer mortality rates for white males and
vs. average radon level in living areas of homes, lung cancer mortality
tends to decrease with increasing radon levels. This is in sharp contrast
to the increase expected from the fact that radon is believed to cause
and Chairman Emeritus Dr. T.D. Luckey, Dept. of Biochemistry of the
U. Missouri-Columbia School of Medicine concurs (1994) with Cohen's
conclusions on the health effects of home radon: "There is a strong negative correlation between
the radon in homes and lung cancer mortality in males, p<0.001. About
90% of the population of the United States resides in the 1730 counties
represented. Cohen obtained comparable data with both males and females.
His results were comparable with corrections for smoking."
Luckey also reports (1995) that: "The optimum chronic
radon (with progeny) concentration for the reduction of lung cancer
mortality appears to be greater than 8 pCi/L. As a public health issue,
BEIR IV states that there are 350 lung cancer mortalities per million
person-WLM (working level month). Radiation from one WL is equivalent
to 100 pCi radon with progeny. Their model suggests home radon would
cause 700 lung cancer deaths per million persons at 100 pCi per liter
of radon and progeny and 70 per 10 pCi/L. In contrast, Cohen's data
indicate that one million people would have 250 fewer lung cancer deaths
at 5 pCi/L radon (with progeny) than at 0.5 pCi/L."
Emeritus Dr. Sohei Kondo discusses (Kondo 1993, Section 4.2.1) Cohen's
earlier work and confounding factors: Cohen tested the
linear no-threshold hypothesis on data covering 411 US counties vs.
age-adjusted mortality rates for lung cancer in 1950-69 for white females
and males. Then, women were not heavy cigarette smokers, spent a large
fraction of their lives at home and seldom migrated from one place to
another. Ecological studies are susceptible to confounding. Cohen carried
out multiple regression analyses of potential confounding factors. Cigarette
smoking is the most important cause of lung cancer. When cigarette sales
by state were applied, the negative slope for dependence on radon levels
was essentially unchanged. Residents of Misasa [Japan], an urban area
where there are radon spas, showed significantly lower mortality from
cancers at all sites than residents of the suburbs of Misasa."
Sadao Hattori, Vice President of CRIEPI reports (1994) that:
Cancers in the people of Misasa villages, with high radon levels in
drinking water, were compared adjacent villages and all Japan. The negative
correlation result was significant.
Emeritus Myron Pollycove, MD, of Laboratory Medicine and Radiology,
UCSF, reports (1994) on radon and lung cancer that: BEIR
IV predicts that lifetime mortality risk of lung cancer is increased
by 10.8% per pCi/L. However, no epidemiologic evidence supports BEIR
IV. To the contrary, studies in the US, Sweden, Finland, and China with
radon up to 12 pCi/L, as well as in areas below the average radon concentration
of 1 pCi/L, have demonstrated a negative correlation of lung cancer
with radon. Cohen's 1992 study addresses 54 socio-economic variables
(SEV) as confounding factors, and all criticisms of these studies, with
excellent statistical power. An unrecognized confounding factor requires:
(1) strong correlation with lung cancer, comparable to cigarette smoking,
but still unrecognized; (2) strong correlation, of opposite sign, with
radon levels; (3) not strongly correlated with any of the 54 SEV; and
(4) it must apply to many
geographic areas and be independent of altitude and climate. It must
have increased by orders of magnitude, and be more important in males,
since the beginning of this century, with effects on females rapidly
catching up in recent years. These properties are most difficult to
meet singly, while to satisfy the four simultaneously becomes incredible.
The more likely explanation of the results is that stimulated biological
defense mechanisms more than compensate for the radiation 'insult' and
are protective against cancer in a low dose, low dose rate range.
Emeritus, and Member of the UN Scientific Committee on the Effects of
Atomic Radiation (UNSCEAR), of the Central Laboratory for Radiological
Protection, Dr. Zbigniew Jaworowski also discusses (1995a) home radon
and lung cancer: Epidemiological studies of a relation
between the radon levels in homes and lung cancer seem to also disagree
with the non-threshold principle, and may suggest a hormetic effect.
In the US, Cohen's study covering 89% of the population. the people
living in houses with radon air concentration higher than average level
were found to have a lower mortality from lung cancer (Cohen 1993).
an abstract, Drs. D. J. Etherington, D. F. Pheby , F. I. Bray also report
(1996) on radon and cancer: The incidence of 14 major cancers
in Devon and Cornwall were examined vs radon levels. Lung cancer incidence
was very similar across all domestic radon categories. Only non-melanoma
skin cancers, showed a significant increase in incidence in the high-radon
vs low-radon sectors, for both sexes. The remaining 12 cancer sites
showed no significant trend with increasing radon concentration. There
was no significant difference in corrected survival rates for any cancer
site between the low-and high-radon areas.
From the abstract of a study on childhood cancers, Parker and
Craft report (1996) that: The effective radiation doses received
by children living in high radon areas are similar to those which have
been associated with an excess risk of malignant disease elsewhere.
However, the only cancer known to be associated with radon is lung cancer,
a disease which is not a condition of childhood.
T. Sobue of the National Cancer Center Institute and his collegues in
Japan report (1997) on the Misasa radon area: Misasa town
was divided into high and low exposure areas. Compared to Tottori prefecture,
the incidences from cancer were generally low, though not statistically
significant except that for female in high exposure area (SIR=0.76,
95% CI=0.62-0.91). Stomach cancer in the high exposure area was significantly
lower for males (SIR=0.72, 95% CI=0.53-0.96). Caution is needed since
individual exposure level was not measured and major confounding factors,
such as smoking, could not be controlled in this study.