Re: HP Newsletter - Effects of Low Doses

[Bernard L Cohen <blc+@pitt.edu>]

On Mon, 15 Sep 1997, Bob Flood wrote:

> risk increase is evident at 20 rem and above. He also says that a more
> recent study (Pierce et al., 1996) found "substantial" risk at 5 to 10 rem.

	--Using Pierce's data, there is no evidence for a cancer risk
from radiation below 20 rem. In fact, there is a 30% probability that
doses in that range are protective against cancer.

> Later he says that the Oxford Study of Childhood Cancer (1970) found
> increased cancer among children up to age 15 following in utero exposure at
> dose between 1 and 2 rem.

	--This is a long and complicated story, and there are several
other studies. For example, there was no evidence for increased childhood
cancers among the Japanese A-bomb survivors.
> 
> Doesn't this idea apply to the aggregate of low-dose epidemiological
> studies? I have not (personally) compiled a summation of study results, but
> it seems to me that I've seen about as many negative coreletion results as
> positive, and most can't find any corelation. If no relationship existed
> between low doses and cancer risk, that's exactly what I would expect from
> a variety of studies where the ambient cancer rate is significant.
> 
> It seems to me that a citation of one particular study from the multitude
> of studies is selecting only the data that fit the hypothesis, and excludes
> the data that don't. Am I over-simplifying?

	--I strongly agree with you.