Development of a Hierarchical Exposure Coding System for Clinic-Based Surveillance of Occupational Disease and Injury

Abstract

The Association of Occupational and Environmental Clinics (AOEC) has developed a database containing standardized data on cases of occupational disease and injury seen in its 50 member clinics in the United States and Canada. AOEC case reports serve as a unique and broad-based surveillance tool to describe occupational and environmental diseases in relation to known agents, as well as to alert occupational health professionals to potential new health hazards. This article focuses on the development of a coding system for chemical, physical, and biological exposures believed to be causally related to each diagnosis. For a number of different reasons, exposure histories obtained in a clinical setting frequently identify classes of causative agents rather than specific exposure agents. The disorder may result from exposure to multiple agents, such as organic solvent-induced neurotoxicity. Even if a work-related condition is related to only one exposure, it may not be necessary to research the exact exposure in order to diagnose and treat the patient. Thus, it may not always be possible, or clinically necessary, or accurate to provide a specific compound as an exposure, and our exposure codes have to allow a certain level of generality. A further consideration in developing exposure codes was how exposures could be grouped to best summarize the cases reported to this large database. Exposure codes have been developed to: (1) be systematically organized by chemical structure or other determinants of toxicologic effect; (2) allow precise classification of discrete exposures likely to be reported by AOEC clinicians; (3) allow designation of codes for broad exposure classes when discrete exposures are not known; (4) be easy to use if the coder is not a chemist, toxicologist, or industrial hygienist; (5) be hierarchically organized to facilitate summary description and analysis either by precise exposures or by exposure groups; and (6) be compatible with development of a computerized exposure code look-up application. The new coding system assigns codes to approximately 750 chemical, biological, and physical exposures, grouped into 38 categories. Codes are numerical and hierarchically arranged to allow easy retrieval of discrete or grouped exposures. Most chemical exposure categories are based on chemical structure; however, some materials are grouped primarily according to use or toxicologic effect. Hunting, K.L.; McDonald, S.M.: Development of a Hierarchical Exposure Coding System for Clinic-Based Surveillance of Occupational Disease and Injury. Appl. Occup. Environ. Hyg. 10(4):317–322; 1995.