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In a study conducted in 1969 and 1970 lactating cows were given oral or intravenous (I.V.) doses of radiotungsten. Blood, milk, urine and feces were collected and analyzed to measure transfer rate and quantity of tungsten eliminated over an extended period during and after exposure. Several lactating and nonlactating cows were sacrificed to measure tissue distribution of radiotungsten and several calves were sacrificed following oral administration of radiotungsten to determine the distribution in rapidly growing Young.The average per cent of administered dose secreted per liter of milk at peak activity was 0.01 and 0.1 for the groups receiving oral and I.V. doses, respectively. During the 84-hr period after dosing, 79% of the orally administered dose was recovered, with 64% recovered in the feces, 14.6% in urine and 0.4% in milk. In the same time period, 68% of the intravenous dose was recovered with 65% in urine, 2% in the milk and less than 1 % in feces.Tissue distribution results indicate the principal sites of short-term radiotungsten deposition were skin, liver and soft tissue. Long-term retention sites in mature cows were bone, muscle and skin. Long-term retention sites in calves were bone, adrenal, skin and spleen. INTRODUCIlONAs THE human young are dependent on milk as a staple food source, milk-borne radionuclides may be a significant source of exposure for this critical segment of the population. Studies with dairy cows designed to measure the milk transfer of various radionuclides provide important information for estimating the potential hazard from the milk link in man's nutrient chain. Of equal importance to the rapidly growing teenager and young adult is the protein derived from beef cattle. A study of the distribution and concentration of radionuclides in the tissues of beef cattle is a necessity if the populace is to be properly protected in the event of an accidental release of radionuclides.

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