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Re: Alleged Deadly toll of Chernobyl

Please take this also into consideration:

http://www.iaea.org/worldatom/inforesource/bulletin/bull383/cardis.html

Long-term health effects
Report by E. Cardis, International Agency for Research on Cancer, France,
who served as Scientific Secretary of Topical Session 3: "Longer-term
effects", Prof. A.E. Okeanov, Centre for Medical Technology, Belarus, who
served as the Session's Vice-Chairman, and by V.K. Ivanov, Medical
Radiological Research Centre, Russian Federation, and A. Prisyazhniuk,
Scientific Centre for Radiation Medicine, Ukraine, who both served on the
Session's Expert Committee.*



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If the experience of the survivors of the Japan atomic bombing and of other
exposed populations is applicable, the major expected radiological impact of
the Chernobyl accident will be deaths from cancer. The total lifetime
numbers of excess cancer deaths will be greatest among the "liquidators"
(emergency and recovery workers employed in 1986-87) and among the residents
of "contaminated" territories. Any estimate of this excess is very unclear
because of uncertainties in individual doses and in the exact magnitude of
effects of low-dose protracted radiation exposure. Currently, however, our
best estimates are: some 2000 extra cancer deaths lifetime among almost
200,000 liquidators from 1986 and 1987; and 4600 deaths among some 6.8
million residents of contaminated territories. Increases of this magnitude
would be extremely difficult to detect epidemiologically against an expected
background number of 41,500 and 800,000 cancer deaths, respectively, among
the two groups.

On the basis of the data from other populations exposed to radiation, the
major radiological impact expected to date (i.e. within the first ten years
after the accident) is leukaemia. The increase is mainly expected among
liquidators; indeed, if the experience of the atomic bomb survivors is
applicable, the increase in this population should be detectable
epidemiologically. Increases in leukaemia among liquidators have been
reported, but they are not consistent. They are, moreover, difficult to
interpret: the cases have not all been verified yet and the increases may
reflect the effect of increased surveillance of the liquidators and
under-registration of cases in the population in countries where systematic
centralized cancer registration was limited at the time of the Chernobyl
accident. No consistent increase has been reported to date. However, the
present reports concern only a two-year period and the ability to detect
such an increase is much reduced.

Increases in thyroid cancer among those exposed as children were observed in
the more heavily contaminated regions of Belarus, Ukraine, and Russia, at
rates much higher than predicted from previous studies. These increases may
reflect either particular sensitivity of the population, due to host or
environmental factors; or under-estimation of doses to the thyroid; or a
higher carcinogenic potential of very short-lived iodine isotopes. Increases
in thyroid cancer are now also reported among liquidators and the general
population; for reasons mentioned above, these must, however, be verified
before attributing them to the Chernobyl accident.

There is a tendency to attribute fluctuations and/or increases in cancer
rates over time to the Chernobyl accident. It should, however, be noted that
increases in the incidence of several neoplasms have been observed in some
countries in the last decades, prior to the accident. A general increase in
mortality has been reported in recent years in many regions of the former
USSR which does not appear to be related to radiation levels. This must be
taken into account when interpreting the results of studies.

Increases in the frequency of a number of non-specific detrimental health
effects other than cancer among exposed populations, particularly among
liquidators, have been reported. It is difficult to interpret these findings
because exposed populations undergo a much more intensive and active health
follow-up than the general population.

Based on results of animal experiments, it is possible that in addition to
cancers, a small increase in hereditary disorders may occur following
radiation exposure. On the basis of these data, the predicted occurrence of
genetic effects induced by radiation from the accident would be very low,
ranging from 0 to 0.03% of all live births and from less than 0.1% to 0.4%
of all genetic disorders among the live births to the exposed population.

When considering predictions of the likely health effects of radiation from
the Chernobyl accident, it is important to recognize that the current
estimates of doses to exposed populations are uncertain; in particular,
doses received early after the accident are not well known. The exposures
received by populations due to the Chernobyl accident are, moreover,
different (in type and pattern) from those of the survivors of the atomic
bombing of Japan. Predictions derived from studies of those populations are
therefore uncertain. Although an increase in thyroid cancer in children as a
result of the Chernobyl accident was envisaged, the extent of the increase
was not foreseen. Only ten years have passed since the accident, and on the
basis of epidemiological studies of other populations, any increases in the
incidence of cancers other than leukaemia are usually not visible until at
least ten years after exposure. Therefore it is essential that monitoring
the health of the population be continued to assess the public health impact
of the accident, even if an increase in cancers caused by radiation from
Chernobyl (except leukaemia among liquidators and thyroid cancer) may be
difficult to detect.

Epidemiological studies of selected populations and diseases are also needed
in order to study observed or predicted effects; careful studies may in
particular provide important information on the effect of exposure rate and
exposure type in the low to medium dose range and on factors which may
modify radiation effects. As such, they may have important consequences for
the radiation protection of patients and of the general population in the
event of any future accidental exposure. Both cohort and case control
studies are generally much more powerful than descriptive studies for
investigating dose relationships. To be informative, however, studies of the
consequences of the Chernobyl accident must fulfill several important
criteria: they must cover very large numbers of exposed subjects; the
follow-up must be complete and non-selective; and precise and accurate
individual dose estimates (or markers of exposure) must be available. In
particular, the feasibility and the quality of epidemiological studies
largely depend on the existence and the quality of basic population-based
registers, and on the feasibility of linking information on a single
individual from different data sources.

In conclusion, ten years after the Chernobyl accident, there is, apart from
the dramatic increase in thyroid cancer in those exposed as children, no
evidence of a major public health impact to date of radiation exposure as a
result of the Chernobyl accident in the three most affected countries. No
major increase in all cancer incidence or mortality has been observed that
could be attributed to the accident. In particular, no major increase has
been detected in rates of leukaemia - even among liquidators - one of the
major concerns after radiation exposure. This is generally consistent with
predictions based on studies of other radiation-exposed populations, in
particular the survivors of the atomic bombings in Japan.



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* The authors are indebted to L. Anspaugh, Lawrence Livermore National Lab,
United States, a member of the Expert Committee, and to consultants K.
Mabuchi, Radiation Effects Research Foundation, Japan, and I. Lichtarev,
Department of Scientific Centre for Radiation Medicine, Ukraine.

----- Original Message -----
From: Norman & Karen Cohen <norco@bellatlantic.net>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Sent: Monday, April 24, 2000 10:36 PM
Subject: Re: Alleged Deadly toll of Chernobyl


> To Radsafers:
>
> Thanks for all the replies about Chernobyl. There's much here to read and
digest.
> I appreciate the tone of your letters. While we may never agree on many
issues, there is no reason not to have dialogue.
>
> I'll be back with some comments and questions in a couple of days.
>
> Peace,
> Norm Cohen
>
>
>
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> The RADSAFE Frequently Asked Questions list, archives and subscription
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