Monday, June 22, 2015

Exposure Modeling Research - The Time is Now

For someone who has been advocating the modeling of exposure estimation for many years, it is very heartening to see research in this area taking root and growing.

Twenty-four years ago this spring, a friend and colleague, Neil Hawkins, suggested that I meet with a young woman who was an IH working for Dow Corning.  Her name was Susan Arnold and Neil said that she was very bright with a lot of energy and that I should talk with her about exposure modeling.   I contacted Susan and we went out to dinner at the AIHA Annual Conference in Salt Lake City in the spring of 1991.    We have been friends and colleagues ever since and Susan has worked as a modeler ever since.   Indeed, she received her Master’s Degree with a modeling project and will defend her PhD thesis on modeling at the University of Minnesota later this summer.  Suffice it to say that Neil and I are very proud of Susan and her accomplishments.  

At this month’s conference of the American Industrial Hygiene Association in Salt Lake City, I and many of my colleagues were treated to some of the excellent work coming out of the University of Minnesota under the leadership of Dr. Gurumurthy Ramachandran or, as many of us know him, Ram.  

On the 24th anniversary of our first meeting in Salt Lake City, Susan presented three papers on modeling which I will mention very briefly here and send her slides to whomever asks for them.

For many years Susan, Ram, Perry Logan, John Mulhausen and others have been interested in investigating the nature, power and accuracy of “expert judgement” within the realm of industrial hygiene.    Indeed, since the beginning of the profession the mantle or cloak of “expert judgment” has been invoked most times an IH would declare  a particular exposure scenario to be “safe” or in need or further investigation.   The term was so ubiquitous that it begged to be defined.  This was done in the latest (and I believe earlier editions of) AIHA Exposure “Strategies Book”.  The quote below is from the 3rd Edition:
“The application and appropriate use of knowledge gained from the formal education, experience, experimentation, inference, and analogy.  The capacity of an experience professional to draw correct inferences from incomplete quantitative data, frequently on the basis of observations, analogy and intuition.”   

The nature of professional judgment of Industrial Hygienists has been put to the test by asking them to use their judgment to characterize well-described exposure scenarios (without monitoring data) by placing them in one of 4 bins; namely, less than 10% of the OEL,  10-50% of the OEL, 50 – less than 100% of the OEL and greater than or equal to the OEL.  When asked to do this without information provided by modeling they systematically underestimated the true exposure.

Note: Even when you have monitoring data, characterizing or placing the exposure  in the correct bin is challenging.  If you do not believe me, read a previous blog on the Smart Phone App:  IH DIG (  Play IH DIG and you will understand. 

Susan’s three presentations get into the issue of professional judgment aided by modeling while putting some of the most popular models through their paces in both the laboratory and real world.   The titles of the three talks she presented are:

  • Evaluating Model Performance under Highly Controlled Conditions
  • Evaluating Model Performance under Real World Conditions
  • Predicting Construction Related Silica Exposure Using Input from Chamber and Field Studies

 As mentioned above, send me an email request ( and I will send you these slides.

Research into exposure assessment modeling is really just getting started; there is still plenty of room for folks to get involved in this growing field.  Indeed, as Susan wrote in the last conclusion of one of her talks:  “A very young science… there is still much to learn!

No comments:

Post a Comment