Changes

== Presence in environment ==

== Presence in environment ==

Polonium-210 is naturally present in all environmental media at very low concentrations. In soils, the concentration is similar to that of uranium, averaging about 1 pCi/g (or one trillionth curie per gram). Because polonium-210 is produced from the decay of radon-222 gas, it can be found in the atmosphere from which it is deposited on the earth’s surface. Average annual air concentrations

Polonium-210 is naturally present in all environmental media at very low concentrations. In soils, the concentration is similar to that of uranium, averaging about 1 pCi/g (or one trillionth curie per gram). Because polonium-210 is produced from the decay of radon-222 gas, it can be found in the atmosphere from which it is deposited on the earth’s surface. Average annual air concentrations

range from 0.005 to 0.04 pCi/m3. Polonium-210 is also emitted to the atmosphere during the calcining of phosphate rock as part of the production of elemental phosphorous. Although direct root uptake by plants is generally small, polonium-210 can be deposited on broad-leaved vegetables. Deposition from the atmosphere on tobacco leaves results in elevated concentrations of polonium-210 in tobacco smoke, resulting in greater intakes in smokers compared to non-smokers. It is estimated that the average Western diet includes from 1 to 10 pCi of polonium-210 per day. Polonium-210 can be significantly elevated in residents of northern lands who subsist on reindeer that consume lichens, which absorb trace elements from the atmosphere.

range from 0.005 to 0.04 pCi/m3. Polonium-210 is also emitted to the atmosphere during the calcining of phosphate rock as part of the production of elemental phosphorus. Although direct root uptake by plants is generally small, polonium-210 can be deposited on broad-leaved vegetables. Deposition from the atmosphere on tobacco leaves results in elevated concentrations of polonium-210 in tobacco smoke, resulting in greater intakes in smokers compared to non-smokers. It is estimated that the average Western diet includes from 1 to 10 pCi of polonium-210 per day. Polonium-210 can be significantly elevated in residents of northern lands who subsist on reindeer that consume lichens, which absorb trace elements from the atmosphere.

== In the human body ==

== In the human body ==