Most big medical studies today are based more on statistical analysis, than any kind of direct cause and effect scientific proof. (Probably all kinds of studies do this now).
So you get a million or two veteran medical records, DNA samples, and answered questionnaires, and dump it all in a big database, and then you can say that PTSD (or whatever) is more prevalent in this DNA type (and other things) than others.
VA (for veteran pay and medical treatment) presumes whole laundry lists of diseases result from radiation exposure (nuke weapons, accidents, storage or propulsion), or asbestos exposure (mostly shipyards and ships), or herbicide (agent orange) exposure. The vast majority of these legal presumptions are entirely based on statistical studies, with no direct medical proof that A actually causes B at all. (And while I've never seen the actual numbers, I know that these presumptions are based on rather small percentages, not huge statistical anomalies)
Of the entire list of diseases presumed by VA to be causally related to herbicide exposure*, only the skin diseases of
porphyria cutanea tarda (extreme sun sensitivity) (PCT) and Chloracne are known and proven to result from physical exposure to herbicide agents, and they have to show up to a degree of 10 percent disabling within one year after actual exposure for service connection to be granted. All the other diseases presumed by VA to be related to herbicide exposure are based solely on statistical studies.
Statistical studies are certainly relevant, but I find it amazing that the big medical institutions like the National Institutes of Health, VA, CDC, with all their technology, expertise and big funding have never been able to actually provide simple proof that A causes B in so many things.
If you develop any other disease on this extensive list (besides PCT or Chloracne), at any time after service (like 50 years later), if you were exposed to herbicide agent during service (set foot in Vietnam for one minute changing planes, or at other listed locations at certain times), then it is presumed your exposure caused that disease for VA pay and medical treatment coverage. It's pretty generous (and liberal).
Interestingly, one minute on the ground in Vietnam will presume exposure, but a full tour on a Naval vessel in Yankee Station will not do it. B-52 pilots flying over Vietnam are also out.
*
https://www.publichealth.va.gov/exposures/agentorange/conditions/index.aspAnd Agent Orange was never orange in color.
The other interesting thing (to me) is this: In the whole world of left and right polarized politics, I cannot think of one other area where both sides strongly advocate for veteran's benefits, care and coverage, survivors benefits, education benefits, burial, and VA guaranteed loans.
Apparently neither side finds anything to gain in a ....
lets screw the Veterans platform.
They even got together and created an entirely new Federal Court for Veterans appeals.
Not that Veterans don't deserve their Country's gratitude, but it seems unique in American politics.
