Re:Babies Affected by Dads' X-Ray Exams

["John Moulder" <jmoulder@post.its.mcw.edu>]

> it makes me wonder what kind of Journal can publish stuff like this.

It's a main line epidemiology journal, and like most such journal's it is full 
of studies that report "associations" without any real concern about 
statistical significance, biological significance, or the rationality of the 
underlying hypothesis.  That's what a lot of epidemiology is like these days.

At least in this case (unlike Environ Health Persp and Wing et al) they did 
not issue the press release until after publication and distribution of the 
issue.  The Wing et al article, by the way, has still not been published.

This article is:  KM Shea & RE Little, Is there an association between 
preconception parental x-ray exposure and birth outcome?  Amer J Epidem 
145(6):546-551, 1997.

> The scientific evidence is so weak that even they admit the 
> differences observed are not significant...

Correct, the results reported are not statistically significant, the p values 
for the 3 measures they used were 0.064, 0.078 and 0.12.

The effect is also not biologically significant.  The adjusted (sex, maternal 
smoking, etc) birth weights were:
Exposed:   3.32 (95% cl: 3.24-3.39) kg
Unexposed: 3.39 (95% cl: 3.37-3.40) kg

There is no dose-response, as they did not make any attempt to estimate dose.

> Is this the same Journal which published the Wing study???

No.

> Yet another example of preconceived opinion, masquerading as science. 

No, I think it's another example of "risk factor" epidemiology that looks for 
associations in large data bases without any real concern for hypotheses.

These people have a large data base of birth outcomes and a broad range of 
environmental factors, social factors, psychological factors and genetic 
factors that might be associated with "adverse" birth outcome.  They can and 
will mine "mine" this database for hundreds of different associations.



John Moulder (jmoulder@its.mcw.edu)
Radiation Biology Group
Medical College of Wisconsin