Identification of determinants of exposure: consequences for measurement and control strategies

xposure to chemical, physical, and biological agents in the workplace is difficult to characterise.A worker's exposure is never constant over time.Workers within groups with similar tasks and working environments are rarely uniformly exposed.Hence, assigning workers to ''exposed'' and ''unexposed'' groups or to exposure categories becomes a problem.Insight is required into the reasons why exposure variability exists, how large this variability is, and which factors determine differences in exposure levels among workers.This knowledge is essential in design, conduct, and interpretation of epidemiological studies and workplace intervention programmes.In recent years statistical techniques have become available that allow simultaneous evaluation of the magnitude of variance components as well as determinants of this variability.These techniques are powerful instruments in the design of measurement strategies in epidemiological studies and in implementation of control and prevention strategies to reduce hazardous exposure.