Editing Radon (section)

==== Absorption and ingestion from water ====
The effects of radon if ingested are unknown, although studies have found that its biological half-life ranges from 30 to 70 minutes, with 90% removal at 100 minutes. In 1999, the US [[National Research Council (United States)|National Research Council]] investigated the issue of radon in drinking water. The risk associated with ingestion was considered almost negligible;<ref>[http://www.nap.edu/openbook.php?isbn=0309062926 Risk Assessment of Radon in Drinking Water]. Nap.edu (2003-06-01). Retrieved on 2011-08-20.</ref> Water from underground sources may contain significant amounts of radon depending on the surrounding rock and soil conditions, whereas surface sources generally do not.<ref>{{cite web |url=http://water.epa.gov/lawsregs/rulesregs/sdwa/radon/basicinformation.cfm |title=Basic Information about Radon in Drinking Water |access-date=2013-07-24 }}</ref> Radon is also released from water when temperature is increased, pressure is decreased and when water is aerated. Optimum conditions for radon release and exposure in domestic living from water occurred during showering. Water with a radon concentration of 10<sup>4</sup>&nbsp;pCi/L can increase the indoor airborne radon concentration by 1&nbsp;pCi/L under normal conditions.<ref name="Thad. Godish 2001" /> However, the concentration of radon released from contaminated groundwater to the air has been measured at 5 orders of magnitude less than the original concentration in water.<ref>{{Cite web |last=Johnson |first=Jan |date=28 October 2019 |title=Answer to Question #13127 Submitted to "Ask the Experts" |url=https://hps.org/publicinformation/ate/q13127.html |access-date=2024-09-23 |website=Health Physics Society}}</ref><!--The ocean surface only carries about {{val|e=-4}} <sup>226</sup>Ra, where measurements of <sup>222</sup>Rn concentration have been 1% over various continents.<ref name="agupubs.onlinelibrary.wiley.com" />--> 

Ocean surface concentrations of radon exchange within the atmosphere, causing <sup>222</sup>Rn to increase through the air-sea interface.<ref name="agupubs.onlinelibrary.wiley.com">{{Cite journal|url=https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/JC080i027p03828|doi=10.1029/JC080i027p03828|title=Radon 222 from the ocean surface|year=1975|last1=Wilkening|first1=Marvin H.|last2=Clements|first2=William E.|journal=Journal of Geophysical Research|volume=80|issue=27|pages=3828–3830|bibcode=1975JGR....80.3828W}}</ref> Although areas tested were very shallow, additional measurements in a wide variety of coastal regimes should help define the nature of <sup>222</sup>Rn observed.