Abstract This commentary describes developments in occupational exposure science over the last 30 yr, highlighting theoretical descriptions of inhalation, dermal, inadvertent ingestion, and ocular exposure in the workplace and how they are intertwined. In particular, the way that we define “exposure” in the theory determines what is and is not measured in workplace investigations, and what contextual information about the work and the environment is recorded alongside the exposure measurements. Central to all the theoretical models described is the unifying concept of uptake, or the mass of hazardous substance entering the body by different routes over a workday. Measurement of uptake is currently practicable for inhalation exposure, although further methodological developments are needed to allow uptake measurement for the other relevant exposure routes. Little attempt has been made to date to try to integrate worker behaviour into exposure assessment, despite this clearly being an important determinant of exposure. It is argued that adopting a new exposure paradigm, centred on uptake, would bring many advantages and provide new insights into workplace exposures.