Inappropriate parameterization of an exposure metric for the study of occupational and environmental hazards may lead to significant misclassification and biased results.

A model for identification of an optimal expression for cumulative exposure that includes exponentiated terms for concentration and time was developed.

When the values of the exponents are allowed to vary, an optimal expression for cumulative exposure may be identified.

The approach has advantages for the study of chronic hazards, in that it is flexible, limits the number of assumptions, and incorporates many of the models generally suggested in the literature.

In addition, the model results may be interpreted to suggest particular pathophysiologic mechanisms.