Lung uranium

Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of the element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/1. 

Uranium can enter the human body orally, by inhalation, and through the skin and mucous membranes. Uranium compounds, both soluble and insoluble, ate absorbed most readily from the lungs. In the blood of exposed animals, uranium occurs in two forms in equiUbrium with each other as a nondiffusible complex with plasma proteins and as a diffusible bicarbonate complex (242). 

Radon (Rn) and Radon Decay Products Radon is a radioactive gas formed in the decay of uranium. The radon decay products (also called radon daughters or progeny) can be breathed into the lung where they continue to release radiation as they further decay. 

Plutonium has a much shorter half-life than uranium (24.000 years for Pu-239 6,500 years for Pu-240). Plutonium is most toxic if it is inhaled. The radioactive decay that plutonium undergoes (alpha decay) is of little external consequence, since the alpha particles are blocked by human skin and travel only a few inches. If inhaled, however, the soft tissue of the lungs will suffer an internal dose of radiation. Particles may also enter the blood stream and irradiate other parts of the body. The safest way to handle plutonium is in its plutonium dioxide (PuOj) form because PuOj is virtually insoluble inside the human body, gi eatly reducing the risk of internal contamination. 

Kunz E., Sevc J. And Placek V., 1978, Lung Cancer Mortality in Uranium Miners, Health Phys., 35, 579-580. 

Sevc J., Kunz E. and Placek V., 1976, Lung Cancer in Uranium Miners and Long-Term Exposure to Radon Daughter Products, Health Phys.,... 

Whittmore A.S. and McMillan A., 1983, Lung Cancer Mortality Among U.S. Uranium Miners A Reappraisal, J.Nat.Cancer Inst. 71, 489-499. 

The histological types of lung cancer seen to excess in uranium miners reflect those in the population at large (Masse, 1984). These occur almost entirely in bronchial airways. Approximately 207 are adenocarcinomas which occur in peripheral bronchioles (Spencer, 1977) where there are no basal cells. Squamous cell cancers predominate in miners exposed early in life to relatively low concentrations of radon daughters (Saccomanno et aJL., 1982). These are considered likely to arise from the secretory small mucous granular cells which undergo cell division and extend to the epithelial surface (Masse, personal communication). Division of these cells is accelerated after irritation by toxicants such as cigarette smoke or infectious diseases (Trump et a L., 1978). 

S. Wood and R. Mick, Age Factor in Histological Type of Lung Cancer in Uranium Miners, a Preliminary Report, in Radiation Hazards in Mining (M. Gomez, ed) pp. 675-679, Society of Mining Engineers, New York (1982). 

In order to establish a causal relationship rather than a pure association between the suspected carcinogen Rn-d and the induced effect lung cancer it is most important to know the individual Rn-d exposure. This is the particular weakness of all these studies since these measurements were not carried out fifteen to thirty years ago, this essential information cannot be provided by any of the available retrospective studies with a sufficient degree of reliability and accuracy (Steinhausler, in press). Therefore they have to rely on indirect estimation of past Rn-d exposure levels, using e.g. inference from uranium ore content. 

Whittemore, A. S. and A. McMillan, Lung cancer mortality among U. S. uranium miners A reappraisal, JNCI 71 489-499 (1983). 

Cross, F., Palmer, R., F. and Busch, R., H., Influence of Radon Daughter Exposure Rate and Uranium Ore Dust Concentration on Occurrence of Lung Tumors, in Proc. of the Specialist Meeting on the Assessment of Radon and Radon Daughter Exposure and Related... 

However, most of it was still in the thorax (either in lung or lymph nodes). The 144Ce in this case may have been serving only as a tracer for the vehicle, uranium, as did the l44Ce in fused aluminosilicate particles. 

Roscoe R et al Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters.262 629, 1989... 

Kusiak RA, Ritchie AC, Muller J, et al Mortality from lung cancer in Ontario uranium miners. BrJ Ind Med 50 920-928, 1993... 

After inhalation exposure, the primary route of excretion is in the feces following ciliary clearance from the lungs to the gastrointestinal tract (Wrenn et al. 1981). Fecal excretion may account for as much as 97% of total excretion (Fisher et al. 1983). Higher levels of thorium-230 were excreted in the feces by active crushermen (uranium mill workers exposed to uranium ore dust in the crusher building) compared to retired workers or controls (Fisher et al. 1983). Levels of thorium-230 in the urine were comparable to those of retired workers, and the levels in both were significantly greater than controls. 

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