Sunday, July 27, 2014

Banning or Applying ALARA to “Evil” Chemicals

According to the National Research Council’s Glossary: ALARA is an acronym for controlling exposure to a chemical "as low as (is) reasonably achievable,”.  It is just slightly higher on the scale of ultimate controls that culminates in outright banning.   The word “reasonably” as used here is clearly open to interpretation. 

I recently wrote a blog about using dose-response modeling to assess the risk of contact allergy.  This particular blog resulted in quite a bit of spirited discussion/debate over whether the technique had any value at all.    One responder suggested that exposure to any and all allergens should be controlled using ALARA especially for highly induced or sensitized individuals. 

Indeed, on the face of it, it is hard to argue that the exposure to the specific allergens for these folks should be keep as low as “reasonably” achievable.   Indeed, there’s that  r-word again! 

Let us take the case of Type IV contact allergens (of which poison ivy is a well-known example of a “natural” allergen of this type).  I have worked in this area for many years and my understanding is that many of the preservative employed to keep our water-based products fresh (including cosmetics) is a Type IV contact allergen.   Is the amount of these preservatives in products as low as reasonably achievable?   Some would argue that it is not.   These products definitely deliver a dose of allergen every day to any person with dermal exposure to them.   It also gets into the air from these products and other treated products (like treated wood or treated water) which also exposes people.

We could BAN the use of allergens in these products so that the amount of these clearly identified allergens could be ZERO and the risk of Type IV contact allergy from their exposure would be ZERO as well.  But is that truly reasonable?   What are the economic implications of having all of these products with dramatically and perhaps unreasonably reduced or essentially eliminated useful shelf-life?

My sense is that this is exactly why we do human health risk assessment and why we use dose-response modeling to predict the risk of common environmental exposure levels.   If we are smart, we do not rely on modeling alone but also on historical, clinical and epidemiological data to tell us if these models are an appropriate portrayal of reality.   In the case of the model I discussed in the blog, it does not have or assume a threshold of response or risk.   There is always some finite risk predicted at any exposure above ZERO.   Some number of folks on the hypersensitive end of the population curve would be predicted to respond.

How large this subpopulation of hyper-susceptible persons might be is clearly a matter for debate and deliberation by the stakeholders (i.e., a proper democratic/political process).   What I believe is not open to debate is that it should not be ZERO; that is, the product should not be banned.

In my opinion banning any product is equivalent to declaring it to be evil.   That is, attributing a malevolent characteristic to an inanimate object.    This is a form of animism or a belief that inanimate objects have spirits which has generally been rejected by modern Western Society.
My sense is that we should be using the rational assessment of risk by applying the best tools available to us while considering the uncertainty.  If the risk is considered too high politically at any particular concentration then it should be used at a lower concentration determined to present a risk which is not unacceptable.  In the example we have been discussing, if that concentration is not effective as a preservative then the material would not be used in that application.  This is rational, analysis-based restriction, not banning.

Clearly, folks on the hypersensitive end of the spectrum – those who might be expected to react at concentrations allowable for the general population – will want to take steps to lower their exposure even more.   I would certainly support product labeling requirements to facilitate this process.   

I believe that it all comes down to doing the best for the most and drawing the lines (as risk managers) or informing the position of the lines as risk assessors. 

Question for Group Discussion:  What is your “gut check” for an exposure/ risk that is not unacceptable?   My answer:   Any exposure that I would allow my children to experience.

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