What is ACCEPTABLE Risk?

In this week’s blog I go out on a limb, the topic is ACCEPTABLE RISK.

More than a few years ago, a then newly minted PhD, friend and colleague; Jack Hamilton asked my opinion about rules one might use to set a level of exposure and risk as ACCEPTABLE.   Being older and a lot grayer than Jack, I got to render my opinions.  I decided to share these opinions with you in this week’s blog to hopefully stimulate some discussion.  I do not pretend to have all, or maybe any, of the answers but I am willing shared my opinions to shine a light into this somewhat dark area in the hopes of bringing out additional discourse from you, my intelligent readers.

Finding and declaring ACCEPTABLE Risk Levels are almost never easy.   If it were easy we would have a life that was more dull and more people could do our jobs.  The question of risk acceptability is political and social.  Acceptable to who?  When?  The answer(s) always has (have) been a mix of politically recognized and derived subjective VALUES.

I have heard some folks on the extreme political left declare that Risk Assessment is a “Tool of the Capitalist Devil”.   I believe that to the extent that anyone independently determines what is "acceptable"for OTHER stakeholders this harshly worded judgment may have a ring of truth.  

Perhaps my most important mentor as I was learning and developing in this field was Dr. Irv Rosenthal.  Irv was a wonderfully intelligent and wise person and a gifted teacher.  Irv reminded me that we often ask permission to pass someone in a narrow hallway.  We say “excuse me” or “peg your pardon”.  Why then, Irv asked, would we not seek their permission to render them at risk (however small) from exposure to compounds we introduce into their environment?  Why can't they participate in drawing the line relative to their own exposures and the putative consequences?

The situation with Human Health is such that we look for consensus among industrial colleagues, academics, regulators and judges as to what are historically "acceptable" levels of risk.  We get benchmarks like 1 in 1000 lifetime risk for carcinogens exposure to workers and 1 in 1,000,000 for non-workers.  This has been evolving somewhat in the courts (e.g., US Supreme Court Benzene decision) but I do not think it has ever been put directly to the ultimate stakeholders, those being exposed.  These folks personally deal with exposure and risk and my sense is that, properly educated and, much more important, properly empowered, I think they would come up with doable and workable limits.  

I mentioned this possibility at an American  Industrial Hygiene National Conference in a Forum on Risk Assessment in the 1990s and the reaction was somewhat predictable.  Very few expressed a willingness to open the process up to these type of potential complications and "problems."  I admit that it will not be easy - I just think it will be ultimately necessary to make the process more politically viable, legitimate and inherently ethical.

So to answer Jack’s question succinctly, I advised him to use his skill to determine the quantitative level of exposure and risk as best he could.  I suggest that, if pressed, he leave the issue of “acceptability” to the first viable choice from the following rough hierarchy.

    1. A "Gold Standard" or criteria you were given by the client or that the client agreed to.   Note:  This is also known as “Rendering unto Caesar those things belonging to Caesar”.

    2. A criteria that is acceptable to some standard-setting or regulatory authority AND seems to make sense to you.

    3. An unwritten but generally accepted "rule of thumb" or common practice that you can refer to and makes sense to you. 

    4. Your "gut feel" on what it should be. 

In every case above, it would be beneficial to identify which line of the above hierarchy was used and the reasoning for using it within the report.   Doing so is particularly important for #4.  Indeed, my advice to Jack was to avoid using #4 unless you are asked specifically to do so by the client OR you have an overwhelming personal need to make your opinion known.   We should always to keep in mind that the determination or declaration of ACCEPTABLE risk is a somewhat subjective risk management function and it is not strictly speaking risk assessment.

Finally, I believe that there should be a new line at the top of this hierarchy that does not exist yet:

Acceptable risk defined in quantitative terms by consensual agreement among all the principal stakeholders.   My sense is that this is a worthy goal.