No abstract

Five human subjects inhaled a mixture of stable and radioactive mercury vapor for periods of 14 to 24 minutes. The subjects retained an average of 74% of that inhaled. Evidence is submitted to show that the retention occurred almost entirely in the alveoli. For 3 days after exposure, the exhaled breath was passed at intervals through activated charcoal traps for sampling periods of 10 to 35 minutes. The data indicated that an average of 7% of the retained mercury was lost in the expired breath, with a half time of 18 hours. Examination of the subjects in a whole body counter yielded average half times for mercury clearance from different parts of the body as follows: lung, 1.7 days; head, 21 days; kidney region, 64 days; chest, 43 days; and whole body, 58 days.

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.

No abstract

No abstract

On the assumption that the potassium content of the lean body mass is constant, it should be possible to estimate fat content in living man from a measurement of potassium-40 activity in the whole-body scintillation counter. A series of such measurements on children and young adults shows good correlations with skin-fold thickness and weight/height ratio as indices of fatness.

Four experiments were performed in which two subjects on two occasions drank approximately 1 pc radon plus daughters in 100 ml of water. Measurements on radon loss in expired air, whole body Radium C content, and radon in the blood permit the calculation of an (MPC), of 2.0 x lo-* pc/ml for occupational exposure. This is based on the stomach as the critical organ, but doses to the lung, kidney, and liver are estimated.

No abstract