Establishing Similar Exposure Groups Lecture 4 IH&S 725 Dr. Myers, C.I.H.
Why? • Not needed for OSHA compliance sampling • So why do it? • Represents best practice IH&S 725 Dr. Myers C.I.H.
The goal….. • To assess the exposures and occupational health risks for all workers to all environmental agents on all days IH&S 725 Dr. Myers C.I.H.
The challenge…… • Is to do it accurately and efficiently, despite the diversity of exposures across workers and across time. IH&S 725 Dr. Myers C.I.H.
The how to….. • One strategy for meeting these challenges is to assemble workers, thought to have similar exposures, into a group • Qualitative or quantitative characterization of the exposure of one or a few in the group is then considered "representative" of the exposures of everyone in the group IH&S 725 Dr. Myers C.I.H.
The benefit…. • Stratification of workers into "similar exposure groups" (SEGs) allows limited resources to be better used to characterize the many exposures that may be present in a particular workplace over different periods of time. IH&S 725 Dr. Myers C.I.H.
The definition….. • Similar exposure group (SEG) are groups of workers having the same general exposure profile because of the similarity and frequency of the tasks that they perform, the materials and processes with which they work, and the similarity of the way that they perform the tasks IH&S 725 Dr. Myers C.I.H.
Two general methodologies for defining a SEG • Observational approach IH&S 725 Dr. Myers C.I.H.
Two general methodologies for defining a SEG • Operational and sampling approach IH&S 725 Dr. Myers C.I.H.
A “workable approach” to develop and use SEGs • Use the observational approach as the primary, default approach to defining SEGs • Assess exposures for the SEGs formed by observation IH&S 725 Dr. Myers C.I.H.
A “workable approach” to develop and use SEGs • Identify critical SEGs for which the consequences of misclassifying an individual worker's exposure are very severe • Use exposure monitoring and statistical analysis to check and refine critical SEGs using the sampling approach IH&S 725 Dr. Myers C.I.H.
Establishing Similar Exposure Groups by Observation • Established by using the information gathered during the basic characterization of the workplace, workforce and exposure agent(s) • Observational approach allows the IH to make initial judgments about exposures to form SEGs and prioritize them for further action IH&S 725 Dr. Myers C.I.H.
Establishing Similar Exposure Groups by Observation • SEGs established by observation are generally described by….. IH&S 725 Dr. Myers C.I.H.
Hierarchical strategies for establishing SEGs by observation • Classifying by process and exposure agent • Classifying by process, exposure agent, and job and/or task • Classifying work teams • Classifying non‑repetitive work IH&S 725 Dr. Myers C.I.H.
Establishing Similar Exposure Groups by Sampling • Measured exposure values are used to classify workers into SEGs • Workers grouped with a given amount of similarity and a given amount of confidence • Has the advantage of objectivity • Can be more accurate than classification by observation IH&S 725 Dr. Myers C.I.H.
Establishing Similar Exposure Groups by Sampling • Good idea but…… IH&S 725 Dr. Myers C.I.H.
Some summary thoughts….. • SEGs are needed to efficiently assess the exposures for each and every worker, each and every day • SEGs are generally described by the following determinants IH&S 725 Dr. Myers C.I.H.
Some summary thoughts….. • An exposure assessment program will be forced by problem scope and limited resources to group workers into SEGs and prioritizing those SEGs for further information gathering or health hazard control • In doing so the industrial hygienist will accept the risk of possibly miss classifying some workers. IH&S 725 Dr. Myers C.I.H.
Some summary thoughts….. • As the exposure assessment and management system matures the IH can identify those SEGs where the risk posed by individual misclassification is a concern • Those critical SEGs can then be targeted for more extensive exposure monitoring using statistical analysis of the monitoring data to check the SEGs and re‑assign individuals as necessary. IH&S 725 Dr. Myers C.I.H.