Abstract
In the absence of current and/or historical monitoring data, qualitative and semiquantitative methods have been used for estimating historical exposure to chemicals in retrospective occupational studies. Two semiquantitative exposure assessment methods—the Job Exposure Matrix (JEM) and the Interview-Based Evaluation (IBE)—were introduced in the early 1980s. Both methods have some advantages and disadvantages in terms of accuracy and feasibility. In order to overcome the disadvantages of these earlier methods, three semiquantitative methods are proposed as possible alternative methods to the JEM and the IBE methods for estimating historical exposures. Two of the proposed methods—the Exposure Source Evaluation (ESE) and the Job Function Evaluation (JFE) methods—are based on information of current and historical working conditions, which can be obtained from walk-through surveys and interviews with long-term employees. The third method—the Parallel Agent Evaluation (PAE) method—is based on the availability of exposure data to an agent different from the agent under consideration.
In this study, historical exposures to phenol were estimated for selected job titles from five different phenol-formaldehyde plants using the three proposed methods. For the PAE method, existing historical exposure data on formaldehyde were employed to estimate retrospective exposures to phenol. Estimates were evaluated in terms of agreement among the proposed methods. Direct exposure assignment was made for each job title/area/plant/year combination, and quantitative estimates were developed after reviewing monitoring data and conducting walk-throughs at the study plants.
Comparison of the semiquantitative methods was carried out in terms of the number of estimates required by the methods, the level of complexity of the decision-making processes, and the amount of the time spent by the industrial hygienist who applied the methods. Advantages and disadvantages of each approach are discussed.