Do industrial hygienists underestimate exposures by taking small sample bases?
At the AIHce 2018 Donald E. Cummings Memorial Award Lecture, Mark Stenzel, CIH, FAIHA, argued that industrial hygienists should place greater emphasis on estimating exposures relative to conducting sampling. Stenzel, an industrial hygiene consultant and the 2018 recipient of AIHA’s Cummings Award for outstanding contributions to the knowledge and practice of industrial hygiene, made his remarks on the final day of AIHce EXP 2018.
Stenzel’s lecture, “Modernization of the Exposure Assessment Process,” criticized what he described as a tendency of industrial hygienists to rely too heavily on a small number of samples to characterize exposures. This over-reliance reflects a mistaken belief that sampling and comparing the results to an occupational exposure limit represents the “gold standard” of exposure assessment, Stenzel said. Calling such an approach “heavily biased,” Stenzel argued that it causes industrial hygienists to underestimate exposures.
“This is a failure for the workers,” Stenzel said, because “we’re not going to be recommending protection when they really need it.”
Because sampling is a highly variable activity, small numbers of samples alone are likely to paint an incomplete picture of an exposure scenario.
“There’s workplace, work force, and work practice variability,” Stenzel said. “There’s variability if the same person is taking a sample at the same location 15 minutes apart.”
In many cases, Stenzel explained, not enough time or money is available to conduct sampling, which is expensive and time consuming. Employers often need industrial hygienists to deliver an exposure judgment in a matter of hours, while the process of sampling could take weeks to complete given the need to wait for laboratory analysis. And if a workplace is changing a work practice or introducing a new process, industrial hygienists will need to assess potential exposures in the absence of sampling.
Published peer-reviewed papers that show that even experienced industrial hygienists typically underestimate exposures when opportunities to conduct sampling are limited, according to Stenzel. One study suggested that a short training session on accurate estimation of exposures significantly improved industrial hygienists’ exposure judgments. Another study found no significant difference between inexperienced and experienced industrial hygienists in the quality of their exposure judgments.
Industrial hygienists often refer to the importance of “professional judgment,” yet Stenzel argued that the term is poorly understood. “There's a misconception that professional judgment is professional opinion,” he said. He clarified that professional judgment reflects the capacity of an experienced professional to draw correct inferences from incomplete quantitative data.
Stenzel called for the American Board of Industrial Hygiene, which administers the Certified Industrial Hygienist credential, to assess CIH candidates’ abilities to implement, administer, and effectively interpret the results of an exposure assessment process.
“If we keep doing what we're doing, we’re going to keep getting what we're getting,” Stenzel said.
An article on exposure judgment accuracy, “Judgment Day: How Accurate are Industrial Hygienists' Qualitative Exposure Assessments?” (AIHA member login required) appeared in the January 2014 Synergist.
Source: Ed Rutkowski, chief editor, The Synergist (a publication of the American Industrial Hygiene Association)