Radioactive Mercury Distribution in Biological Fluids and Excretion in Human Subjects after Inhalation of Mercury Vapor

Abstract

The distribution of mercury in red blood cells (RBCs) and plasma, and its excretion in urine and feces are described in five human subjects during the first 7 days following inhalation of radioactive mercury vapor. A major portion (98%) of radioactive mercury in whole blood is initially accumulated in the RBCs and is transferred partly to the plasma compartment until the ratio of mercury in RBCs to plasma is about 2 within 20 hr. The cumulative urinary and fecal excretion of mercury for 7 days is about 11.6% of the retained dose, and is closely related to the percent decline in body burden of mercury. There is little correlation between either the urinary excretion and plasma radioactivity of mercury, or the specific activities of urine and plasma mercury, suggesting a mechanism other than a direct glomercular filtration involved in the urinary excretion of recently exposed mercury. These studies suggest that blood mercury levels can be used as an index of recent exposure, while urinary levels may be an index of renal concentration of mercury. Howver, there is no reliable index for mercury concentration in the brain.

Relation of mercury exposure to elemental mercury levels in the urine and blood.

“…In the stud y by Nakaaki et al (10), inorganic mercur y taken up in the body was excreted rather slowly; an increase in urinary excretion became evident after 10 d of exposure at 40-60 j.lg /m ' . Cherian et al (2) also found that mercury is pooled in the kidney before entering the urine, and the biological half-time for mercury loss from the kidney is approximately 64 d. As numerous investigators have already noted, urinary concentrations of inorganic mercury would tend to reflect levels of chronic exposure , perhaps kidney accumulation of mercury, rather than those of recent exposure. It appears therefore that the urinary excretion of elemental mercury is faster than that of inorganic mercury and, moreo ver, can be expected to reflect the levels of individual exposure on that same day.…”

Blood mercury levels of dental students and dentists at a dental school

“…22 This circulating mercury is partitioned between packed cells and plasma. 23 Improvement of technical equipment and better standards of hygiene, however, can reduce exposure significantly. The way in which amalgam is prepared, cleaning habits, and types of floor coverings have been pointed out to be important factors.…”

Mercury

“…before the steady state has been reached, has not been extensively described in the literature. At least 50% of the mercury in the blood compartment is cleared with a half life of about three days (2). Blood, therefore, probably indicates recent exposure.…”