Toxicological considerations epidemiological studies

Hecdth effects data come from three types of studies clinical, epidemiological, and toxicological. Clinical and epidemiological studies focus on human subjects, whereas toxicological studies are conducted on animals or simpler cellular systems. Ethical considerations limit human exposure to low levels of air poUutants which do not have irreversible effects. Table 7-1 lists the advantages and disadvantages of each type of experimental informahon. 

In recent years life science researchers have become more earnest in their considerations that trace elements have important roles in physiology and pathology. So far, some of these experimenters have used activation analysis (1) to measure the elemental contents of biological tissues and fluids (2) to determine if a correlation exists between abnormal trace element concentration and certain types of diseases (3) as an investigational method for epidemiological functions (4) to measure metabolic functions (5) as a clinical and investigational method for toxicology (6) in total body in vivo studies (7) in in vivo studies with stable tracers and (8) in individual identifications for forensic requirements. 

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