OBJECTIVES The study aimed at developing a model for the retrospective assessment of exposures in epidemiologic studies when little or no data on past exposures are available.

METHODS A deterministic model was developed for the level of exposure by industrial hygienists involved in an international study on cancer risks among phenoxy herbicide or chlorophenol manufacturing workers and pesticide sprayers. The general source-receptor model was used as the conceptual framework for the model.

RESULTS The model included variables related to job, the emission of chemicals, contact with chemicals, personal protection, and other relevant determinants of exposure. Cumulative dose indices were calculated from the duration of exposure (from the work histories) and the level of exposure (from the model).

CONCLUSIONS Deterministic modeling in complex exposure situations may provide more valid and reliable results than its conventional alternative, subjective assessment by an expert.