To other federal agencies, exposure is defined as contact between a chemical (of any type) and the outer boundary of an organism. CDC, in about the same manner, defines exposure as:
Exposure: Contact with a substance by swallowing, breathing, or touching the skin or eyes.OHSA defines occupational exposure...the kind experienced by C-123 aircrews, as:
Occupational Exposure means reasonably anticipated skin, eye, mucous membrane, or parenteral contact with blood or other potentially infectious materials that may result from the performance of an employee's duties.But the VA needed to create its own definition. Not that there was anything incorrect or unscientific in standard medical or scientific definitions of exposure...its just that VA needed to create a definition to prevent exposure claims. All the other, scientifically correct definitions were, in fact, accurate but that was exactly why VA needed to create its own. Accuracy, and scientific correctness, were what VA saw as the problem in standard definitions of exposure.
VA needed to change the meaning of the word to prevent exposed veterans from qualifying for treatment of Agent Orange exposures. Here's what the VA invented in their Post Deployment Health Section of Veterans Health Administration, in response to staff members insisting that no C-123 veterans would be permitted to have their Agent Orange exposure claims approved:
VA's Office of General Counsel explained, VA hasn't needed to define the word "exposure" before. There hadn't been any need, because for one thing, VA never pretended to have the regulatory or scientific authority, or the need, to create its own unscientific and policy-oriented definition of the word. For nearly every situation, the standard reference of Dorlands Medical Illustrated Dictionary was ideal for every occasion.
But that need to come up with VA's own definition, however unscientific, arose just as soon as C-123 veterans pointed out the 1991 Agent Orange Act, and the multiple postings in the Federal Register all very clearly specify "exposure' as the single qualification for veterans to be able to seek VA medical care for Agent Orange-related illnesses.
So VA couldn't easily escape the obligation, oft-repeated, of honoring exposure claims and thus it simply changed the definition of the word...at least, within the VA. That's how the DOD, USPHS, CDC,NIEHS, EPA, NIH, OSHA, WHO, and all other government agencies consider C-123 veterans to have been exposed to Agent Orange, but the VA uses its private, and very unique, redefinition just so that the vets' claims can be denied.