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Re: Hormesis?
Radsafers,
Forgive my bit of agitation/frustration/confusion. On the one hand we have
opinions, based on certain observations, and stated forcefully, that
radiation (quite a bit) is potentially good for you, and on the other hand
the assertion, based on other observations, that one gamma-photon or alpha
may cause cancer. Where on earth does the truth lie? I suspect that the
latter assertion may, or may not, describe a smaller or bigger part of a
mechanism. Stated blandly like this, it negates (or, at least, does not
quantify) the coefficient expessing the probability for a resulting cancer,
which must be an exceedingly small number ('may' = ten to a large negative
exponent). "Radiation, after all, is a weak carcinogen". There are
'anecdotal' reports from very high natural background areas where the
inhabitants are purportedly alive and well. Can somebody please provide
references to scientific studies to back this up. I notice on a slide
presented at a conference on the Wismut remediation in Saxony, Germany,
that time-integrated radon measurements in about 20% of the houses in ten
affected towns would equate to effective annual doses above the radiation
worker yearly limit, and almost 1% were in excess of 10 times this limit.
Does anybody have references to scientifically studied health effects?
Think of the zillions of potential cancer-causing alphas in more than 15000
Bq/m^3 (equated to > 240 mSv/a). After generations, how is it possible
that anyone emerged alive? Have they? A proper evaluation of possible
health effects in such a situation with relatively reliable occupational
records would surely make more sense than statistically marginal studies in
other situations. Can anybody supply references to such studies?
My own thoughts.
Chris Hofmeyr
chofmeyr@nnr.co.za
Quote from
NECNP <necnp@necnp.org>
2001/01/23 17:56
>Snip
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- -- - - - -
>The new British study was conducted by the Radiation and Genome Stability
Unit at Harwell in association with Mount Vernon Hospital in London. Groups
of human blood cells were exposed to a single alpha particle in the
laboratory and left to divide a dozen times or more.
Researchers found that 25% of the daughter cells had distinctive patterns
of broken and bent chromosomes. This effect, christened "radiation-induced
genomic instability", is thought to be part of the complex chain of
biological events that can end up as cancer. "This work shows directly for
the first time that even a single alpha particle can induce genomic
instability in a cell. That may be important in assessing risks of cancer
from alpha-emitting radionuclides in the body," said the Harwell unit's
director, Professor Dudley Goodhead.
"It suggests that even the smallest amount carries some, very small, risk.
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Snip
Further:
"Harry Hinks"
<harryhinks@hotmai To: Multiple recipients of list
l.com> <radsafe@romulus.ehs.uiuc.edu>
Sent by: cc: (bcc: Christoph Hofmeyr/CNS1)
radsafe@romulus.eh Subject: Hormesis?
s.uiuc.edu
2001/02/07 18:17
Please respond to
radsafe
I read most of Mr. Muckerheide's abstracts he referenced. Overall they all
come from the same institute and are sight permutations of each other.
They
also involve whole body x-ray irradiation. Is there any evidence that
alpha
particle irradiation to the lung is beneficial. These recent articles do
not appear to support that.
Br J Cancer 2001 Jan;84(1):134-140
Lung cancer in lifetime nonsmoking men - results of a case-control study in
Germany.
Kreuzer M, Gerken M, Kreienbrock L, Wellmann J, Wichmann HE
BfS - Federal Office of Radiation Protection, Institute of Radiation
Hygiene, Ingolstaedter Landstrasse 1, Neuherberg, 85764
Epidemiological studies of lung cancer among nonsmoking men are few. This
case-control study was conducted among lifetime nonsmoking men between 1990
and 1996 in Germany to examine lung cancer risk in relation to occupation,
environmental tobacco smoke, residential radon, family history of cancer
and
previous lung disease. A total of 58 male cases with confirmed primary lung
cancer and 803 male population controls who had never smoked more than 400
cigarettes in their lifetime were personally interviewed by a standardized
questionnaire. In addition, 1-year radon measurements in the living and
bedroom of the subjects' last dwelling were carried out. Unconditional
logistic regression was used to calculate odds ratios (OR) and 95%
confidence intervals (CI). Having ever worked in a job with known lung
carcinogens was associated with a two-fold significantly increased lung
cancer risk (OR = 2.2; Cl = 1.0-5.0), adjusted for age and region. The
linear trend test for lung-cancer risk associated with radon exposure was
close to statistical significance, demonstrating an excess relative risk
for
an increase in exposure of 100 Bq m(-3)of 0.43 (P = 0.052).
Nonsignificantly
elevated effects of exposure to environmental tobacco smoke in public
transportation and in social settings were observed. No associations with a
family history of cancer or previous lung diseases were found. Our results
indicate that occupational carcinogens and indoor radon may play a role in
some lung cancers in nonsmoking men. Copyright 2001 Cancer Research
Campaign.
------------------------------
Proc Natl Acad Sci U S A 2001 Jan 9
Direct evidence for the participation of gap junction-mediated
intercellular
communication in the transmission of damage signals from alpha -particle
irradiated to nonirradiated cells.
Azzam EI, de Toledo SM , Little JB
Department of Cancer Cell Biology, Laboratory of Radiobiology, Harvard
School of Public Health, Boston, MA 02115.
It has generally been considered that important biological effects of
ionizing radiation arise as a direct consequence of DNA damage occurring in
irradiated cells. We have examined this hypothesis by exposing cells to
very
low fluences of alpha-particles, similar to those emitted by radon gas,
such
that as few as 1% of the cells in a population are traversed by a particle
and thus receive any radiation exposure. By using the endpoints of changes
in gene expression and induction of DNA damage, we show that nonirradiated
"bystander" cells participate in the overall response of confluent
density-inhibited populations of cultured fibroblast and epithelial cells.
By in situ immunofluorescence techniques and the use of cells genetically
compromised in their ability to perform gap junction intercellular
communication, we present direct evidence for the involvement of
connexin43-mediated intercellular communication in the transmission of
damage signals to nonirradiated cells. Induction of the stress-inducible
p21(Waf1) protein in aggregates of neighboring cells far exceeding the
fraction of cells whose nucleus has been traversed occurred in gap
junction-competent cells only. These changes in p21(Waf1) expression
correlated with both the induction of DNA damage (as measured by
micronucleus formation) as well as increased Ser-15 phosphorylation of p53.
-------------------------------------
J Epidemiol Community Health 2000 Nov;54(11):822-6
Childhood leukaemia in areas with different radon levels: a spatial and
temporal analysis using GIS
Kohli S, Noorlind Brage H , Lofman O
Department of Medical Informatics, Faculty of Health Sciences, Public
Health
Centre, University Hospital, S-581 85, Linkoping, Sweden.
OBJECTIVES: To evaluate the relation between exposure to ground radon
levels
and leukaemia among children using existing population and disease
registers. DESIGN: Ecological correlation study. SETTING: The county of
Ostergotland in Sweden. METHODS: Every child born in the county between
1979
and 1992 was mapped to the property centroid coordinates by linking
addresses in the population and property registers. Population maps were
overlaid with radon maps and exposure at birth and each subsequent year was
quantified as high, normal, low or unknown. This was analysed with data
from
the tumour registry. Standardised mortality ratios (SMRs) were calculated
using the age and sex specific rates for Sweden for the year 1995. RESULTS:
90 malignancies occurred among 53 146 children (498 887 person years) who
formed the study population. SMRs for acute lymphatic leukaemia (ALL) among
children born in high, normal and low risk areas were 1.43, 1.17 and 0.25
respectively. The relative risk for the normal risk group and high risk
group as compared with the low risk group was 4.64 (95% CI 1.29, 28.26) and
5. 67 (95% CI 1.06, 42.27). The association between ALL and continued
residence at normal or high risk areas showed a similar trend. No
association between radon risk levels and any other malignancy was seen.
CONCLUSION: Children born in and staying at areas where the risk from
ground
radon has been classified as low are less likely to develop ALL than those
born in areas classified as normal and high risk.
Harry Hinks
harryhinks@hotmail.com
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