03 November 2011

Agent Orange & the C-123 - A Toxicology Review for Aircrews

The VA has explained, during our October 27 teleconference, that aircrews weren't exposed to dioxin even though the Air Force determined our airplanes to be "heavily contaminated, extremely dangerous, extremely hazardous, and a danger to public health." Their mission, pursued with great dedication, is prevention of our claims for Agent Orange exposure...we advance our claims because we've been exposed and must seek medical care! 

Consider...the VA did not challenge the Air Force studies which established the dioxin contamination...instead, they claimed that we could not have been exposed to the contamination. A fine point, emphasized with the VA key word of PROBABILITY.

So let's sit back and review toxicology, contamination and dioxin and how all this mess affects us and our VA claims.

I believe we can make clear the PROBABILITY of our Agent Orange exposure. Dr. Fred Berman, Director of the Toxicology Department of Oregon Health Sciences University agrees that we have been exposed. Somehow, we need to challenge the DOD and VA positions with a convincing argument.

A while back, I wrote the US Agency for Toxic Substances and Disease Registry for help answering the VA's objections. The Director of the ATSDR responded, complimented our research, and recommended that DOD carefully investigate the situation. Today I started reading documents in the ATSDR collection, and this posting is to cover a few of the basics, as best I can understand them, of Agent Orange contamination and exposure.

This is from the ATSDR's documents explaining how dioxin contaminants can cause exposure.

Human Exposure Pathways 
To determine whether people are or could be exposed to contaminants associated with a property, ATSDR evaluates the environmental and human components that lead to human exposure. An exposure pathway contains five major elements: 

1) a source of contamination, 
2) contaminant transport through an environmental medium, 
3) a point of exposure, 
4) a route of human exposure, and 
5) a receptor population. 
An exposure pathway is considered a complete pathway if there is evidence that all five of these elements are, have been, or will be present at the property.
But dioxin can be found everywhere and while it is dangerous, there must be a point below which no action need be taken, and a contamination point above where action should be taken. 

We all have some amount of dioxin in our bodies. Eating animal fat is the major route of exposure for most people...which is why the AF should have alerted crews of our Agent Orange exposure back in '94...we'd have known to take precautions! For most people, eating a varied, balanced, low-fat diet results in reduced dioxin exposure via ingestion...it will also help your blood pressure, diabetes risks and certain cancers. 

Here is the decision chart upon which the ATSDR bases its approach on how much dioxin is too much dioxin:

ATSDR's Decision Framework for Sites Contaminated with Dioxin and Dioxin-Like Compounds.

Screening Level

£ 50 ppt TEQs
Evaluation Level

>50 ppt but < 1,000 ppt TEQs
Action Level

³ 1,000 ppt TEQs
Health effects are unlikely and further evaluation is not necessary, unless there are community health concerns.Evaluation of site-specific factors, such as
  • Bioavailability
  • Ingestion rates
  • Pathway analysis
  • Soil cover
  • Climate
  • Other contaminants
  • Community concerns
  • Demographics
  • Background exposure
Potential public health actions considered, such as
  • Surveillance
  • Research
  • Health studies
  • Community education
  • Exposure investigations
(De Rosa et al. 1997a)

When contamation is considered, one must also consider the amount of time spent subjected to that contamination at that helps determine exposure. The ATSDR states: 

There are three exposure periods - 
  • acute (less than 15 days) 
  • intermediate (15–364 days)
  • chronic (365 days or more)
In the case of our aircrews, we fall into the "chronic" period regarding contamination exposure because of the full decade we flew the contaminated C-123s.

The VA position is that our crews couldn't have been exposed by contact with the airplane's dioxin-contaminated surfaces...Post Deployment Health stated that the skin is an effective barrier to dioxin. So, if the VA eliminates our dermal exposure, that means they are saying the Vietnam vets were exposed solely via inhalation and ingestion. Sorry, VA...there way too many government studies showing that the principal method of suspected exposure in Vietnam was physical contact with dioxin-contaminated surfaces.

The ATSDR defines exposure pathway:

The route a substances takes from its source (where it began) to its end point (where it ends), and how people can come into contact with (or get exposed to) it. An exposure pathway has four parts:

  •  a point of exposure, such as surface, water well, structure
  •  an environmental media an transport mechanism, such as movement through air or water
  •  a point of exposure, such as eating, drinking, breathing or touching
  •  a receptor population (people potentially or actually exposed)

When all four parts are present, the exposure pathway is termed a completed exposure pathway.

So it seems to me, we have met all four parts of the requirements for a completed exposure pathway. Therefore, we have been exposed. And our exposure was chronic!

Now let's look at the ways we were exposed. First, by physical contact of our skin to dioxin-contaminated surfaces. The 1994 study of Patches made clear its contamination, with dioxin 800% greater than standards for reentering buildings after fires. The EPA reports the absorption of dioxin through the skin has been estimated to range from 0.5 to 3.0% (EPA, 1992a), with assessments typically (conservatively) assuming 3.0%. The 1994 Patches report identified  an average of 617 nanograms per square meter...the "safe" average should be about 85 nanograms per square meter!

Another method of exposure is via inhalation. Dioxin deadly attaches to dust, which then gets kicked up and breathed in.

The final method of exposure likely to happen to aircrews is ingestion...eating the stuff. This would come from eating food which had been in contact with a dioxin-contaminated surface, or drinking water into which dioxin-contaminated dust may have settled. Or one of those great Monsanto Agent Orange Candy Bars!

Of these three methods of exposure, the most likely and the most intense route for aircrews is probably dermal...skin contact. The oils naturally present on our skin readily permit contamination, even though the skin is normally a good protective barrier.

Note that exposure is cumulative. Exposure via the three pathways, exposure for ten years...it all adds up. And there is nothing in the literature from EPA, CDC, ATSDR or any other alphabet department which considers dioxin- contaminated surfaces (such as we had in the C-123) safe...to the contrary, they are identified as unsafe.

For the VA to describe dioxin-contaminated C-123s as aircraft which did not EXPOSE crews to dioxin is stretching science all out of shape. We were exposed. We were exposed. We were exposed!

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