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Linking side effects that develop many years after an exposure to the exposure

Posted Feb 26 2012 12:10am
Over the past two weeks, several people asked me about illnesses they developed a number of years after exposures to the Gulf War, to anthrax vaccine, and to other toxic products.  Because this is an extremely complex subject, and a recurring issue, I thought I should address it in the blog, rather than try to discuss it separately with each person who approached me.

Here are the big questions embodied by the issues raised, imho
  1. Did the exposure cause (or perhaps contribute to) the illness?
  2. Is there is a convincing way to link the original exposure to an illness that only became known many years later?
  3. What kinds of compensation might the person be eligible for?
Some illnesses are known to only be caused by specific exposures, but they are a small minority of illnesses.  An example:  eosinophilia myalgia syndrome, caused by a contaminant in the supplement L-Tryptophan, manufactured by the Showa Denko company of Japan.  This happened to be an early product made from genetically engineered bacteria.  It was a new illness caused by a new toxicant.  This is a very rare occurrence.

Some illnesses are related to a toxic exposures, but not everyone with the illness is known to have been exposed.  Parkinson's disease is much more common in farmers and others exposed to pesticides, but also occurs in the absence of a pesticide exposure.   This probably reflects the general idea that illnesses are due to an interaction between exposures, genetic predispositions, and other factors, such as nutritional state.

Both the VA and wikipedia list the illnesses that have been assigned, over time, as due to Agent Orange (contaminated with the dioxin TCDD) for purposes of a VA disability rating and medical treatment.  Congress granted veterans the "presumption" of disability if they served in Vietnam and developed a designated illness. 

This VA benefit is distinct from an initial settlement of $180 million made by the manufacturers of Agent Orange and attorneys for a Vietnam Veteran class action in 1984. 

Per wikipedia
In 1991, the US Congress enacted the Agent Orange Act , giving the Department of Veterans Affairs the authority to declare certain conditions 'presumptive' to exposure to Agent Orange/dioxin, making these veterans who served in Vietnam eligible to receive treatment and compensation for these conditions. [63] The same law required the National Academy of Sciences to periodically review the science on dioxin and herbicides used in Vietnam to inform the Secretary of Veterans Affairs about the strength of the scientific evidence showing association between exposure to Agent Orange/dioxin and certain conditions. [64]
Through this process, the list of 'presumptive' conditions has grown since 1991, and currently the U.S. Department of Veterans Affairs has listed prostate cancer, respiratory cancers, multiple myeloma, type II diabetes, Hodgkin's disease, non-Hodgkin's lymphoma, soft tissue sarcoma, chloracne , porphyria cutanea tarda, peripheral neuropathy, chronic lymphocytic leukemia, and spina bifida in children of veterans exposed to Agent Orange as conditions associated with exposure to the herbicide. This list now includes B cell leukemias, such as hairy cell leukemia, Parkinson's disease and ischemic heart disease, these last three having been added on August 31, 2010.
Note that diseases were still being added to this list as recently as 18 months ago, for exposures that occurred 40-50 years earlier!

My point is that it can take a long time to identify a statistical relationship and make a causality assessment between an exposure and an illness.  And it can take a long time to develop a related illness after exposure.  In the case of Agent Orange (and probably related herbicides) the connections were only made because of federal legislation that asked the National Academy of Sciences to keep looking into possible connections.

Similar legislation does not exist for most other exposures.  So potential connections are not being made.  And the scientific research that might be used to make them may be sponsored by the manufacturer of the putative toxic substance, with the goal of obscuring a relationship.  For example, despite overwhelming evidence to the contrary, Showa Denko tried to blame overuse of L-tryptophan , rather than a contaminant, for cases of eosinophilia myalgia syndrome.

So it all comes down to politics.  Did Congress face enough pressure to investigate the potential linkage?  Was legislation passed to provide some type of compensation?  Was a viable mechanism set up to review the medical literature in order to identify any linkage?

In the case of illnesses meeting the definition of Gulf War syndrome, if you were physically in the Gulf, and later developed the condition, veterans are eligible for disability benefits and care.

In the case of anthrax vaccine, Congress has provided no remedy for vaccine-related injuries.  There as yet exist no standards for what constitutes an anthrax vaccine injury.  It is difficult or impossible to perform the necessary studies in an unbiased manner, as the Defense Department will not share its data.  And since only soldiers currently receive anthrax vaccine, there is no other modern data.  The Gulf War studies maybe confounded by multiple other exposures, and suffer from the long time that elapsed between the exposures and the self-reports of vaccinations and injuries.

Unless and until the US public demands access to the scientific data it paid for, I see no remedy for this state of affairs.
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