A generalized effective exposure modeling program for assessing dose-response in epidemiologic investigations.

The computer program OCMAP (occupational cohort mortality analysis program) has been extended to allow exposure indices for person-years to be calculated as time-dependent covariates rather than as the usual cumulative indices. The article develops a general formula for weighting exposures and describes the cumulative index, the lag, partial weight, and the lognormal models as specific examples. The implementation in OCMAP is flexible in that it permits these specific models or any other user-specified weighting scheme to be used. Several example schemes are applied to a cohort of workers exposed to arsenic.