Criteria for Judging Epidemiology on the Web

[dj_strom@ccmail.pnl.gov (Daniel J Strom)]

RADSAFErs,

Al Tschaeche <xat@inel.gov> asked, "What are the criteria you use to 
judge the weight of epidemiologic evidence?"

Here is a partial answer to Al's request.  With permission from Federal 
Focus, Inc., Bruce Busby has kindly agreed to put the London principles 
from "Principles for Evaluating Epidemiologic Data in Regulatory Risk 
Assessment.  Developed by an Expert Panel at a Conference in London, 
England, October 1995" (Washington, DC: Federal Focus Inc.) on the web:

http://www.sph.umich.edu/group/eih/UMSCHPS/epidprin.htm

There is much more in the "Principles..." book (address at the web 
site), so please consult it as well.

----

Those are some of the criteria I use to judge the weight of 
epidemiologic evidence for radiation risk management purposes.  
Additionally, one should consider, as John Moulder did yesterday, the 
"Bradford Hill criteria:"

Some of the major factors to consider before inferring that a 
statistical association is a causal one (adapted from Austin Bradford 
Hill, "The Environment and Disease:  Association or Causation?"  Proc. 
Roy. Soc. Med. 58:295-300, 1965):

1.   Strength:  a large effect, e.g., 32-fold lung CA increase in heavy 
smokers.

2.   Consistency:  is effect consistently observed across studies?

3.   Specificity:  specific workers, particular sites and types of 
disease.

4.   Temporality:  exposure must precede disease.

5.   Biological gradient:  dose-response curve.

6.   Plausibility:  biological plausibility depends to some extent on 
how much biology one knows.

7.   Coherence:  cause and effect inference should not seriously 
conflict with generally known facts of the natural history and biology 
of the disease.

8.   Experiment:  does intervention reduce or prevent?

9.   Analogy:  do other, similar agents produce the effects?

BOTTOM LINE:  STRONG STATISTICAL ASSOCIATION ALONE DOES NOT PROVE 
CAUSATION.

----

We all must remember that managing radiation risks goes way beyond the 
scientific basis.  Beyond the science, there are social values, 
traditions, political concerns, financial concerns (which have 
encouraged inaction on indoor radon), national security concerns, and 
regulatory concerns, to name a few.  All come into play in the USA in 
radiation risk management.

- Dan 

The opinions expressed above are my own, and have not been reviewed or 
approved by Battelle, the Pacific Northwest National Laboratory, or the 
U.S. Department of Energy.

Daniel J. Strom, Ph.D., CHP
Staff Scientist
Health Protection Department K3-56
Pacific Northwest National Laboratory
Battelle Boulevard, P.O. Box 999
Richland, WA 99352-0999 USA