Evaluation of Concomitant Biological and Air Monitoring Results

Abstract

The quantitative estimation of dose in epidemiological studies is characterized by two main types of difficulties. The dose often changes widely over time, making its exact estimation a long and costly process for chronic diseases. Although systematic, long-term changes can be dealt with quite easily, short-term, random fluctuations have to be treated statistically. On the other hand, one must admit that target dose can only be measured directly on rare occasions because the biological receptors are, in most cases, inaccessible in studies on workers. Surrogates of target dose, therefore, have to be used, i.e., air exposure or biological indicators. This paper examines advantages and disadvantages of these two approaches, with respect to the difficulties mentioned.

For exposure fluctuations over time, air and biological monitoring are compared, taking into account the half-life of the chemical in the body and also some measure of the biological individual variability. Plots are given to describe how these parameters affect the estimation of long-term exposure by biological monitoring. This is, furthermore, statistically compared to the results that would be obtained by air monitoring.

Considering both air and biological monitoring as surrogates of target dose, various factors are discussed that could modify their respective results: skin exposure, physical workload, aerosol solubility, fate of the chemical in the body. Each of these factors are discussed using pharmacokinetic concepts, and examples are given. A simple model for the prediction of skin absorption compared to respiratory exposure is discussed. Droz, P.O.; Berode, M.; Wu, M.M.: Evaluation of Concomitant Biological and Air Monitoring Results. Appl. Occup. Environ. Hyg. 6:465–474; 1991.