D. Hazards

Date: 2015-10-07; view: 512.

All isotopes and compounds of uranium are toxic, teratogenic, and radioactive. It has been shown that some compounds of uranium could cause renal damage, but no conclusive evidence has yet been produced.

No deaths are causally associated with prolonged occupational exposure to inhaled uranium compounds. Although accidental inhalation exposure to a high concentration of uranium hexafluoride has resulted in human fatalities, those deaths were not associated with uranium. On the basis of the available data, exposure to environmental uranium or to uranium at levels found at hazardous waste sites will not be lethal to humans.

Radiological effects are generally local because this is the nature of alpha radiation, the primary form from U-238 decay. Uranium compounds in general are poorly absorbed by the lining in the lungs and may remain a radiological hazard indefinitely. Uranyl (UO₂⁺) ions, such as from uranium trioxide or uranyl nitrate and other hexavalent uranium compounds have been shown to cause birth defects and immune system damage in laboratory animals.

Finely-divided uranium metal presents a fire hazard because uranium is pyrophoric, so small grains will ignite spontaneously in air at room temperature.

A person can be exposed to uranium (or its radioactive daughters) by inhaling dust in air or from smoking tobacco products which have been grown using certain phosphate fertilizers, or ingesting water and food. The general population is exposed to uranium primarily through food and water; the average daily intake of uranium from food ranges from 0.07 to 1.1 micrograms per day. The amount of uranium in air is usually very small; however, people who live near government facilities that made or tested nuclear weapons, or facilities that mine or process uranium ore or enrich uranium for reactor fuel, may have increased exposure to uranium. Houses or structures which are over uranium deposits (either natural or man-made slag deposits) may have an increased incidence of exposure to radon gas, a radioactive carcinogen.

Uranium can enter the body when it is inhaled or swallowed, or under rare circumstances it may enter through cuts in the skin. Uranium does not absorb through the skin, and alpha particles released by uranium cannot penetrate the skin, so uranium that is outside the body is much less harmful than it would be if it were inhaled or swallowed. When uranium enters the body it can lead to kidney damage. Uranium itself is not a chemical carcinogen.

Uranium mining carries the danger of airborne radioactive dust and the release of radioactive radon gas and its daughter products (an added danger to the already dangerous activity of all hard rock mining). As a result, without proper ventilation, uranium miners have a dramatically increased risk of later development of lung cancer and other pulmonary diseases. There is also the possible danger of groundwater contamination with the toxic chemicals used in the separation of the uranium ore.