Selenium in the blood of South Dakotans.

Determinations of blood selenium levels of the normal human population in and around the state of South Dakota were made and related to known seleniferous areas. With two exceptions, the highest mean values were obtained in regions where animal selenosis has been observed, but whether any of the samples contained enough selenium to indicate a chronic toxicosis cannot be stated. Data on blood, hair, and urine of four Rapid City residents showed no seasonal differences, and the average blood concentrations were consistent with previous findings. Urine concentrations were variable within limits. Hair was found to be unreliable in evaluating the selenium status of people because of the general use of antidandruff shampoos containing the element.