VA: “Exposure = contamination field + bioavailability.”
The term exposure was redefined (from the VA perspective, not by regulatory authorities or industrial standards nor any other peer-reviewed action) to include bioavailability,VA's objective being evasion of requirements in the law for providing exposure care to C-123 veterans. The flyers’ exposures were redefined away with VA’s novel redefinition of exposure. No bioavailability = no exposure =denied claim.
The VA redefinition of exposure was apparently first utilized at the VA’s poster display for Society of Toxicology 2012, where the line appeared as part of the historical perspective of Agent Orange, the focus of the poster. It was an official VA poster, with none of the usual disclaimers about not necessarily reflecting agency typical…indeed, usually recommended, on such scientific displays. After SOT 2012, VA continues to deny veterans’ claims insisting the veterans failed to prove bioavailability.
In fact, the bioavailability requirement was grasped by VA’s Post Deployment Health and included by them in the VA’s poster, Agent Orange: 50 Years of History which staff of Post Deployment Health presented themselves. The VA need for a creative redefinition of exposure became apparent when the Federal Register of 31 August 2010 carried a VA statement that the Department would provide “presumptive service connection” to non-Vietnam War veterans able to prove their exposure to Agent Orange.
Post Deployment Health was faced with either treating the exposed veterans, which policy opposed, plus yet another significant impact on the Department’s health care budget...or VA could create some ways preventing C-123 exposure from being acknowledged.
Thus was born the VA redefinition of a fundamental toxicological term. The VA redefinition is unique, not used elsewhere in science, medicine or government. VA has no statutory or regulatory authority to define such terms. The agencies which do have such authority include the CDC/Agency for Toxic Substances and Disease Registry, and the National Institutes of Health/National Toxicology Program. Both agencies have taken exception to the VA’s redefinition.
In particular, objections were voiced by Dr. Linda Birnbaum, Director of the National Toxicology Program. She wrote,” In all my years as a toxicologist, I have never heard bioavailability as part of the exposure field. Exposure is skin contact (or inhalation or ingestion) with a chemical of any type.”
|courtesy of Professor. R.S. Pollenz, Univ. South Florida|
Bioavailability itself MUST follow exposure , but not all exposures have the subsequent event of bioavailability. Further, bioavailability is a complex concept based on the chemical nature of the agent. There is also the major concept of biotransformation since nearly all compounds are metabolized once they enter the body. TCDD and PCBs however, are somewhat resistant to the biotransformation, since humans do not have enzymes that are able to remove the CL molecules (this is one reason why CL is used as a halogenating agent in creating T45T and other chemicals that kill stuff).
Readers may be able to find similar schematics on line and in some of the toxicology text books. Note that the connections may not be linear and are different for each chemical, but this gives the various terms to keep in mind and the complexity of the process. If there has been an adoption of any term PRIOR to exposure, or definition of exposure to include another subsequent toxicological event as a required component, this is not correct because one MUST be exposed before anything can happen.
Perhaps, VA has been focusing on the bioaccumulation from a standpoint of whether the amount that someone may carry is BIOAVAILBLE to do anything. This has always been a hot area regarding the risk assessment of these halogenated compounds.