On the value of measuring mercury and cadmium concentration in urine.

In connection with "maximum allowable concentrations in biological materials ", I should like to express some views on the value of measuring mercury and cadmium concentrations in urine. These remarks are based on findings in human subjects and in experimental animals. Mercury which is absorbed into the body is largely excreted in the urine. From this. aspect, therefore, determination of the urinary output of mercury might be assumed to be a useful measure of the exposure to mercury. Many investigations have, in fact, demonstrated a correlation between the amount of mercury in the urine and the exposure to mercury, although this relationship has not yet been fully elucidated from the quantitative viewpoint. I should like in this connection to draw attention to some sources of error which are associated with assessment of exposure based on urine analysis.