Influence of individual factors and personal habits on the levels of biological indicators of exposure.

The progressive improvement of hygienic conditions in the workplace has increased the importance of obtaining detailed information on extra-occupational factors that might influence the levels of the biological indicators. This information is indispensable both when subjects belonging to the general population are selected for establishing 'reference values' and when subjects occupationally exposed to specific chemical substances are studied. In non-occupationally exposed subjects the biological indicator levels may be influenced by circumstances which enhance absorption of the substance in question. Examples of interference factors considered for biological indicators of main metals are: gender, age, smoking habits, alcohol consumption and dietary habits. In occupationally exposed subjects the levels of the biological indicators can be influenced by factors that interfere with the metabolism of the substances absorbed in the workplace. In particular, factors such as alcohol, drugs and tobacco appear to play an important role in modifying the biological indicator levels in the occupationally exposed. Ethanol can inhibit as well as induce the metabolism of solvents. Inhibition occurs after excessive ingestion of ethanol, whereas induction occurs in subjects who regularly consume alcohol. There are several examples of inhibition of the metabolism of solvents by alcohol in man, occurring at levels of exposure frequently encountered in the workplace, also within the 'occupational exposure limits', (OEL). Conversely, there are very few studies on the effects of induction, which presumably occur only when the exposure levels greatly exceed OEL. Among drugs, analgesics seem to play a particular role in interfering with the metabolism of solvents. Since cigarette smoking is frequently associated with alcohol ingestion at present it is difficult to extrapolate the isolated effect of smoking on the metabolism of solvents. In order to facilitate interpretation of the results of biological monitoring, we propose to prepare informative sheets for the main substances which will contain information on factors that can influence the levels of the indicators.