Senior Lecturer on Industrial Hygiene
Dr. Herrick’s primary research focus is on the nature and properties of occupational exposures. Rapid global industrialization has created working environments in which people encounter a wide array of physical, chemical, biological, and psychosocial stresses. While there are a few examples of workplace exposures which pose distinctive and readily identifiable disease risks, such as asbestos and vinyl chloride, the association between exposure and work-related impairments, diseases, and injuries is rarely so clear. This research is directed to improving our ability to identify these associations where they exist, to evaluate their strength, and to use this information in developing methods of exposure control to prevent occupational disease and injury.
When exposure is studied as a risk factor for occupational disease, it can be thought of as a process of human interaction with a source of a potential hazard. This way of thinking leads to the development of exposure assessment methods which capture the characteristics of exposure having physiologic significance for the health effect being studied. For example, painters using epoxy-based coatings are exposed to aerosols containing reactive epoxy resin molecules. These epoxy compounds are associated with toxic effects including sensitization and mutagenesis. The painters’ exposure is a complex mixture containing epoxy resin molecules in various stages of reaction. A measurement method which is sensitive only to the final, fully-reacted product can seriously underestimate the effective total epoxy exposure. Limitations such as these may compromise the value of exposure measurements when we consider exposure as a possible cause of the health effects seen in epidemiologic studies of painters. Our method of fully characterizing the reactive properties of the aerosols will improve the value of the exposure measures as a risk factor for disease.
This approach to exposure assessment also evaluates the influence of individual behaviors on the exposure process. We have begun to recognize that inter-individual variability in exposure is much greater than had been supposed, and the failure to account for this variability may result in substantial exposure misclassification in epidemiologic studies. Our research in this area is developing a task-centered approach to characterizing exposure by identifying specific work tasks, and the associated exposures with each to evaluate the variability between individual workers, as well as changes in the composition and intensity of exposure over time. In addition to providing better exposure information for classifying workers in epidemiologic studies, the task-based approach also helps identify specific operations and activities which make the greatest contribution to exposure for a work task, allowing the development of effective, targeted intervention methods to control exposure.
S.D., 1987, Harvard School of Public Health