Analysis of biological material in industrial toxicology.

INTRODUCTION Occupational hazards have existed since the beginning of technology and they have always been considered part of the job. At the present time a different idea and a modern concept about the importance of each individual's health among the working class, has brought about a transcendental change in labour legislation. However, the workmen's compensation laws are not effective enough from either the sanitary or the toxicological point of view. It is necessary to think of detecting any possibility of physiological changes or metabolic disturbances leading to an industrial poisoning, at an early stage, in order to apply corrective technical measures in the working atmosphere thus avoiding the disease long before the symptoms appear. And there is only one way to achieve this purpose: taking advantage of the numerous new laboratory tests which are constantly being developed. Sometimes, months or years of exposure may elapse before toxic manifestations appear. In the meantime the offending agent will be acting upon the sensitive receptors, causing a series of small insults—usually not perceptible—to a group of cells. None of us ignore the extraordinary and ever increasing significance attributed to the enzymes. The understanding of these protein molecules will allow us to know the metabolic activities of living organisms and throw some light into the biological mechanisms by means of which health or disease will show as their dominant feature. When an injurious chemical agent is present in the atmosphere of a working place, the workers are exposed to an occupational disease. An equilibrium is generally established between absorption and excretion, the result of which will be the presence of the chemical and or its metabolites in tissues and body fluids. The determination of the injurious agent in air samples and body fluids may give an indication of the effectiveness of the preventive measures, especially in cases where a good correlation exists between air, blood and urine levels. When complete information is needed in order to give a "biochemical diagnosis", invaluable for the early detection of an occupational disease during the asymptomatic stage, it is necessary to include more apt tests to reveal the slight changes occurring in enzymatic activity due to the presence of small amounts of that injurious agent in the cells. The use of various biochemical tests for the study of the mechanism of action of poisons is taking an ever greater importance in modern toxicology. Of course, the use of such methods requires highly qualified interpretation. The limits of harmless fluctuation, lying within the range of physiological variation, have been set for a number of enzymatic systems. This information may be used to evidence any change in their activity as a consequence