re: cancer clusters

["Sandy Perle" <sandyfl@EARTHLINK.NET>]

Please respond to Gerald Nicholls directly at:

gnicholl@dep.state.nj.us



For most of us, who were educated primarily in the "hard" sciences of

biology, chemistry, physics or engineering, many things that

epidemiologists do in their discipline seem simplistic and even

unscientific.  Others who contribute to this list have been even less

charitable in characterizing their work.  Having spent the last six

years trying to understand a childhood "cancer cluster" in Toms 

River,

New Jersey I think a few thoughts are worth sharing in view of Kai's

question.  If there is a causative agent, radiation is just one of 

the

possibilities.  Some studies have associated leukemia with other

factors.



For example, in the Toms River epidemiological study conducted by the

New Jersey Department of Health and Senior Services and the Agency 

for

Toxic Substances and Disease Registry, leukemia in female children 

under

the age of five was associated with the mother's prenatal consumption 

of

 drinking water from a particular set of wells and proximity to a

Superfund site.  I want to stress the word "associated", no causation

was shown despite many years of diligent work.



Epidemiologists, or, at least the ones I like to listen to, talk 

about

additional factors beyond statistical significance in assessing the

linkage between an environmental factor and an untoward occurrence 

such

as childhood cancer.  Among them are (1) biological plausibility, (2)

dose response effect and (3) agreement of results with other studies. 



Unfortunately, in the Toms River study, the association of the 

mother's

exposure to environmental factors and the incidence of leukemia in

female children under five was not supported by these concepts.  No

argument has been advanced as yet for biological plausibility (why

weren't male children so affected?).  There was not a clear increase 

in

incidence with increasing exposure, and, no other study has shown 

this

particular association.



Perhaps we have to regard epidemiology, when applied to retrospective

studies such as this (and is the case with most radiation studies), 

as a

science that is still pretty much in its infancy.  As technology and

statistical tools improve perhaps so will the science.  If

epidemiologists do not have the opportunity to study "cancer 

clusters",

the technology and the tools will likely never improve, and, neither

will the science. 



My opinions only!



Gerald Nicholls 

gnicholl@dep.state.nj.us



>>> Kai Kaletsch <info@eic.nu> 07/17/02 01:13PM >>>

What is the currently accepted theory behind the leukemia clusters? 

Is

it that they are statistical outliers?



I thought it was that it was viruses introduced by a mobile workforce

into isolated communities. I thought the clusters were reproduced in

other instances where mobile workers came into stable, immobile

communities.



This is not a very pleasant theory. It promotes xenophobia and, to

avoid stigmatizing cancer, bacterial and viral causes are not in 

fashion

("Cancer is not contagious"). It is much easier to blame it on

radiation.



Kai



-------------------------------------------------

Sandy Perle

Director, Technical

ICN Worldwide Dosimetry Service

ICN Plaza, 3300 Hyland Avenue

Costa Mesa, CA 92626



Tel:(714) 545-0100 / (800) 548-5100  Extension 2306

Fax:(714) 668-3149



E-Mail: sandyfl@earthlink.net

E-Mail: sperle@icnpharm.com



Personal Website: http://sandy-travels.com/

ICN Worldwide Dosimetry Website: http://www.dosimetry.com/



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