Kinetic considerations in monitoring exposure to chemicals

The aim of biological exposure monitoring is to estimate the amount of the chemical absorbed in the body of each individual worker. As the concentration of any foreign chemical in body fluids is not constant, but shows an exposure-related fluctuation, this estimation may be successful only when based on knowledge of the behaviour of the chemical in the body, i.e., its kinetics. Skin absorption is one of the reasons for performing biological monitoring of exposure. However, when the absorbed chemical is being monitored in the blood, skin absorption may be a source of considerable error since the concentration of the chemical in the blood specimen collected from the cubital vein does not represent the whole body but only the arm. It should be borne in mind that the errors caused by kinetic variations are similar, independent of the type of measurement performed; thus, they pertain equally to the measurements of chemicals by traditional chemical analytical means and to measurements of the character of the chemical, e.g., mutagenicity.