What we know from World War I is that some of our troops had acute symptoms of exposure to chemicals, had bad health and died because of chemical exposure in World War I.
There's another issue here - and I have some limits as to what I can say - but there's some real question as to the viability of the chemical masks, the protective gear used by our soldiers.
The bottom line is that the CIA knew before the war, during and war, and after the war where most of these chemicals were and most of these biological agents.
The bottom line to this is, there are few doctors who have any expertise in chemical exposure.
Chemical exposure can heighten and quicken other illnesses and make them more acute.