The proclivity of normal tissues for various metals may also shed some fight on the carcinogenic process. Studies on the distributions and concentrations of trace elements in human tissues and especially the accumulation of unusual metals seem to indicate that these phenomena are possibly a function of the age of the vital organs. Spectroscopic studies reveal that many of these metals are absent in corresponding tissues of still born babies. In addition to the better known elements usually associated with biochemical reactions, many others are concentrated by specific tissues. The presence of some metals like aluminum in lung tissue and cadmium in kidney may be the result of environmental factors.

Trace element distribution in the fiver and blood has also been examined. Lower than normal values were found for copper and iron in fatty fivers, and in the blood manganese was variable in concentration, whereas copper and magnesium were constant. Abnormal elements have been considered as possibly important in chronic diseases, and the interactions of abnormal and normal metals have been discussed in sclerosis. Rates of metal turnover in tissues have also been investigated. By use of activation analysis it was shown that the copper content increased in the spleens of tumor bearing animals. More work on trace element content of vital organs during disease states would be useful. Activation analysis could be used to obtain this information.

It may be possible that aging tissue may have different ratios or combinations of metals from those of younger tissue. Reports state that the nickel content of hair increases as its color changes to grey. This seems too pat an answer to a complicated process; furthermore, these results were not corroborated by other groups.