RE: "Scientific Evidence"

["Wright, Will (DHS-PSB)" <WWright2@dhs.ca.gov>]

The P53 gene offers a good model for this discussion in that a great deal is
known about the molecular genetic process. To jump from a possible cause(rad
dose) to a multistep dependent outcome cannot be applied across the
molecular board.  The P53 process is multistep beginning with a point
mutation and ultimately leading to chromosome deletion.  The retinoblastoma
case is a single step point process assuming the affected individual is
initially heterozygous  for the mutation or a two step process assuming the
initial event was environmental or spontaneous and a second spontaneous
homogenotizing event occurred to cause the cancer.  In this second example
and using population probabilities one can make a very convincing case on
either cause or not cause as a population or person event; as to molecular
cause?
		-----Original Message-----
		From:	Sandy Perle [mailto:sandyfl@earthlink.net]
		Sent:	Wednesday, July 26, 2000 12:26 PM
		To:	Multiple recipients of list
		Subject:	Re: "Scientific Evidence"

		Jerry,

		> I wonder just what would constitute "scientific evidence".
Suppose, for
		> example, that a person received a small radiation exposure
(<10 rem) at
		> their work, and years later developed cancer. Since
radiogenic cancer is
		> generally  indistinguishable from other cancers how could
radiation etiology
		> be either proved or disproved?

		A very good question, and, I don't have a very good answer
to it 
		either. I would venture to answer this in the following way.
If the 
		illness can't be distinguished based on either radiation
exposure, as 
		compared to other cancer causative factors, and, then one
would haver 
		to look to the statistics of the extremely large number of 
		occupationally exposed workers, where the database is
extensive, and 
		look at the incidence of cancers (types and time on-set),
look at the 
		cumulative dose history, and, the rate of dose cumulation,
and, look 
		at the families history of cancer and other illness, and the

		individual's habits, such as drinking, smoking and work with
other 
		cancer causing agents, and then determine the "likelihood"
of the 
		cancer being caused by the exposure to radiation, compared
to the 
		other potential causes (similar to a court of law where the 
		preponderance of the evidence is assessed.

		I agree that it is almost impossible to categorically state
the 
		causative factor, in that it may be a combination of
factors.

		On the other hand, I have a personal problem simply stating
that by 
		only having worked in a radiation environment, and the onset
of 
		cancer, or other illness that can also be caused by
radiation, that 
		the cause was the radiation and that the individual receives

		financial compensation.

		As I started this reply, I don't have a concrete answer, but
have 
		provided the best I can at this point.

	
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		Sandy Perle					Tel:(714)
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		Director, Technical				Extension
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