Mobility Patterns of Migrant Farmworkers in North Carolina: Implications for Occupational Health Research and Policy.

Occupational health research often relies on longitudinal data to link exposures and health outcomes. Studies of migrant and seasonal farmworker health face special challenges. Farmworkers are difficult to track, and many occupational health outcomes require considerable time to develop. Using data from two longitudinal studies of farmworker health in North Carolina, we: 1) describe migration during one summer (amount, reasons, destinations); and 2) discuss the implications of these patterns for conducting different types of environmental and occupational health research. Approximately 30 percent of farmworkers migrated over the course of the summer. Analysis of specific work sites revealed both in- and out-migration. Work availability and work-related illness were major causes of out-migration. These data suggest that failing to document reasons for migration may result in underestimation of the occupational illnesses and injuries under study. If research on migrant farmworkers is to be used to establish worksite health and safety policies, traditional research designs and data analysis techniques must be adapted to the realities of worker migration.