Editing Radon (section)

=== Domestic-level exposure ===
Radon has been considered the second leading cause of lung cancer in the United States and leading environmental cause of cancer mortality by the EPA,<ref>{{cite web |date=February 27, 2024 |title=Health Risk of Radon |url=https://www.epa.gov/radon/health-risk-radon |access-date=August 15, 2024 |website=[[Environmental Protection Agency]]}}</ref> with the first one being [[smoking]].<ref>{{cite journal |vauthors=Schabath MB, Cote ML |date=October 2019 |title=Cancer Progress and Priorities: Lung Cancer |journal=Cancer Epidemiol Biomarkers Prev |volume=28 |issue=10 |at=Radon |doi=10.1158/1055-9965.EPI-19-0221 |pmc=6777859 |pmid=31575553}}</ref> Others have reached similar conclusions for the United Kingdom<ref name="Darby05" /> and France.<ref name="Catelinois">{{cite journal |author=Catelinois O. |author2=Rogel A. |author3=Laurier D. |last4=Billon |first4=Solenne |last5=Hemon |first5=Denis |last6=Verger |first6=Pierre |last7=Tirmarche |first7=Margot |date=2006 |title=Lung cancer attributable to indoor radon exposure in france: impact of the risk models and uncertainty analysis |journal=[[Environmental Health Perspectives]] |volume=114 |issue=9 |pages=1361–1366 |doi=10.1289/ehp.9070 |pmc=1570096 |pmid=16966089|bibcode=2006EnvHP.114.1361C }}</ref> Radon exposure in buildings may arise from subsurface rock formations and certain building materials (e.g., some granites).<ref name="Todorovic">{{Cite book |last1=Todorović |first1=N. |title=Radon: geology, environmental impact and toxicity concerns |last2=Nikolov |first2=J. |last3=Petrović Pantić |first3=T. |last4=Kovačević |first4=J. |last5=Stojković |first5=I. |last6=Krmar |first6=M. |date=2015 |publisher=Nova Science Publishers, Inc. |isbn=978-1-63463-742-8 |editor-last1=Stacks |editor-first1=Audrey M. |pages=163–187 |chapter=Radon in Water - Hydrogeology and Health Implication}}</ref> The greatest risk of radon exposure arises in buildings that are airtight, insufficiently ventilated, and have foundation leaks that allow air from the soil into basements and dwelling rooms.<ref name="RECR" /> In some regions, such as [[Niška Banja]], Serbia and [[Ullensvang]], Norway, outdoor radon concentrations may be exceptionally high, though compared to indoors, where people spend more time and air is not dispersed and exchanged as often, outdoor exposure to radon is not considered a significant health risk.<ref>{{Cite journal |last1=Čeliković |first1=Igor |last2=Pantelić |first2=Gordana |last3=Vukanac |first3=Ivana |last4=Krneta Nikolić |first4=Jelena |last5=Živanović |first5=Miloš |last6=Cinelli |first6=Giorgia |last7=Gruber |first7=Valeria |last8=Baumann |first8=Sebastian |last9=Quindos Poncela |first9=Luis Santiago |last10=Rabago |first10=Daniel |date=2022-01-07 |title=Outdoor Radon as a Tool to Estimate Radon Priority Areas—A Literature Overview |journal=International Journal of Environmental Research and Public Health |volume=19 |issue=2 |pages=662 |doi=10.3390/ijerph19020662 |issn=1661-7827 |pmc=8775861 |pmid=35055485 |doi-access=free}}</ref>

Radon exposure (mostly radon daughters) has been linked to lung cancer in case-control studies performed in the US, Europe and China. There are approximately 21,000 deaths per year in the US (0.0063% of a population of 333 million) due to radon-induced lung cancers.<ref name="epa">{{cite web |url=http://www.epa.gov/radon/pubs/citguide.html |title=A Citizen's Guide to Radon |date=October 12, 2010 |work=www.epa.gov |publisher=[[United States Environmental Protection Agency]] |access-date=January 29, 2012}}</ref><ref>{{Cite web |url=https://www.census.gov/quickfacts/fact/table/US/PST045221.html |title=QuickFacts |date=2022-07-01 |work=www.census.gov |publisher=[[United States Census Bureau]] |access-date=2023-03-08}}</ref> In Europe, 2% of all cancers have been attributed to radon;<ref name="Ngoc-2022">{{Cite journal |last1=Ngoc |first1=Le Thi Nhu |last2=Park |first2=Duckshin |last3=Lee |first3=Young-Chul |date=2022-12-21 |title=Human Health Impacts of Residential Radon Exposure: Updated Systematic Review and Meta-Analysis of Case–Control Studies |journal=International Journal of Environmental Research and Public Health |volume=20 |issue=1 |pages=97 |doi=10.3390/ijerph20010097 |doi-access=free |issn=1661-7827 |pmc=9819115 |pmid=36612419}}</ref> in [[Slovenia]] in particular, a country with a high concentration of radon, about 120 people (0.0057% of a population of 2.11 million) die yearly because of radon.<ref>{{Unbulleted list citebundle|{{Cite web|title=Žlahtni plin v Sloveniji vsako leto kriv za 120 smrti|url=https://www.24ur.com/novice/preverjeno/zlahtni-plin-v-sloveniji-vsako-leto-kriv-za-120-smrti.html|access-date=2021-11-02|website=www.24ur.com|language=sl}}|{{Cite web |url=https://www.stat.si/StatWeb/en/News/Index/9212 |date=2021-01-01 |title=Population, Slovenia, 1 January 2021 |publisher=Republic of Slovenia Statistical Office (Source: SURS) |access-date=2023-03-08 |work=www.stat.si |archive-date=2022-01-11 |archive-url=https://web.archive.org/web/20220111171853/https://www.stat.si/StatWeb/en/News/Index/9212 |url-status=dead }}}}</ref> One of the most comprehensive radon studies performed in the US by epidemiologist [[R. William Field]] and colleagues found a 50% increased lung cancer risk even at the protracted exposures at the EPA's action level of 4&nbsp;pCi/L. North American and European pooled analyses further support these findings.<ref name=RECR>{{Cite report|archive-url=https://web.archive.org/web/20100528010149/http://deainfo.nci.nih.gov//advisory/pcp/pcp08-09rpt/PCP_Report_08-09_508.pdf |url=http://deainfo.nci.nih.gov//advisory/pcp/pcp08-09rpt/PCP_Report_08-09_508.pdf |title=Reducing Environmental Cancer Risk&nbsp;– What We Can Do Now |publisher=US Department of Health and Human Services |chapter=Exposure to Environmental Hazards from Natural Sources |pages=89–92 |date=April 2010 |archive-date=May 28, 2010}}</ref> However, the conclusion that exposure to low levels of radon leads to elevated risk of lung cancer has been disputed,<ref>{{Unbulleted list citebundle|{{cite journal |last=Fornalski |first=K. W. |author2=Adams, R. |author3=Allison, W. |author4=Corrice, L. E. |author5=Cuttler, J. M. |author6=Davey, Ch. |author7=Dobrzyński, L. |author8=Esposito, V. J. |author9=Feinendegen, L. E. |author10=Gomez, L. S. |author11=Lewis, P. |author12=Mahn, J. |author13=Miller, M. L. |author14=Pennington, Ch. W. |author15=Sacks, B. |author16=Sutou, S. |author17=Welsh, J. S. |pmid=26223888 |title=The assumption of radon-induced cancer risk |year=2015 |journal=Cancer Causes & Control |doi=10.1007/s10552-015-0638-9 |issue=26 |volume=10 |pages=1517–18|s2cid=15952263 }}|{{cite journal |last=Becker |first=K. |pmid=19330110 |title=Health Effects of High Radon Environments in Central Europe: Another Test for the LNT Hypothesis? |year=2003 |journal=[[Nonlinearity in Biology, Toxicology and Medicine]] |issue=1 |volume=1 |pages=3–35 |pmc=2651614|doi=10.1080/15401420390844447 }}|{{cite journal |author=Cohen B. L. |title=Test of the linear-no threshold theory of radiation carcinogenesis for inhaled radon decay products |journal=[[Health Physics (journal)|Health Physics]] |volume=68 |issue=2 |year=1995 |pmid=7814250 |url=http://www.phyast.pitt.edu/%7Eblc/LNT-1995.PDF |doi=10.1097/00004032-199502000-00002 |pages=157–74|s2cid=41388715 }}}}</ref> and analyses of the literature point towards elevated risk only when radon accumulates indoors<ref name="Nunes-2022" /> and at levels above 100&nbsp;Bq/m<sup>3</sup>.<ref name="Ngoc-2022" />

Thoron (<sup>220</sup>Rn) is less studied than {{Sup|222}}Rn in regards to domestic exposure due to its shorter half-life. However, it has been measured at comparatively high concentrations in buildings with earthen architecture, such as traditional [[Timber framing#Half-timbering|half-timbered houses]] and modern houses with [[clay]] wall finishes,<ref>{{Cite journal|first1=Stefanie |last1=Gierl |first2=Oliver |last2=Meisenberg |first3=Peter |last3=Feistenauer |first4=Jochen |last4=Tschiersch |doi=10.1093/rpd/ncu076 |title=Thoron and thoron progeny measurements in German clay houses |journal=[[Radiation Protection Dosimetry]] |volume=160 |date=April 17, 2014 |issue=1–3 |pages= 160–163|pmid=24743764 }}</ref> and in regions with thorium- and [[monazite]]-rich soil and sand.<ref name="Ramola-2020">{{Cite journal |last1=Ramola |first1=R.C. |last2=Prasad |first2=Mukesh |date=December 2020 |title=Significance of thoron measurements in indoor environment |url=https://linkinghub.elsevier.com/retrieve/pii/S0265931X20306998 |journal=Journal of Environmental Radioactivity |language=en |volume=225 |pages=106453 |doi=10.1016/j.jenvrad.2020.106453|pmid=33120031 |bibcode=2020JEnvR.22506453R }}</ref> Thoron is a minor contributor to the overall radiation dose received due to indoor radon exposure,<ref>{{Cite journal |last=Chen |first=Jing |date=2022 |title=Assessment of thoron contribution to indoor radon exposure in Canada |journal=Radiation and Environmental Biophysics |volume=61 |issue=1 |pages=161–167 |doi=10.1007/s00411-021-00956-0 |issn=0301-634X |pmc=8897316 |pmid=34973065|bibcode=2022REBio..61..161C }}</ref> and can interfere with {{Sup|222}}Rn measurements when not taken into account.<ref name="Ramola-2020" />

==== Action and reference level ====
WHO presented in 2009 a recommended reference level (the national reference level), 100&nbsp;Bq/m<sup>3</sup>, for radon in dwellings. The recommendation also says that where this is not possible, 300&nbsp;Bq/m<sup>3</sup> should be selected as the highest level. A national reference level should not be a limit, but should represent the maximum acceptable annual average radon concentration in a dwelling.<ref>{{Cite book|url=http://whqlibdoc.who.int/publications/2009/9789241547673_eng.pdf |date=2009 |title=WHO Handbook on Indoor Radon |publisher=World Health Organization |archive-date=March 4, 2012 |archive-url=https://web.archive.org/web/20120304001907/http://whqlibdoc.who.int/publications/2009/9789241547673_eng.pdf |isbn=978-92-4-154767-3}}</ref>

The actionable concentration of radon in a home varies depending on the organization doing the recommendation, for example, the EPA encourages that action be taken at concentrations as low as 74&nbsp;Bq/m<sup>3</sup> (2&nbsp;pCi/L),<ref name="EPA radon">{{cite web |title =Radiation Protection: Radon |publisher=[[United States Environmental Protection Agency]] |date=November 2007 |url=http://www.epa.gov/radiation/radionuclides/radon.html |access-date =2008-04-17}}</ref> and the [[European Union]] recommends action be taken when concentrations reach 400&nbsp;Bq/m<sup>3</sup> (11&nbsp;pCi/L) for old houses and 200&nbsp;Bq/m<sup>3</sup> (5&nbsp;pCi/L) for new ones.<ref>{{cite web |url=http://www.euro.who.int/__data/assets/pdf_file/0006/97053/4.6_-RPG4_Rad_Ex1-ed2010_editedViv_layouted.pdf |title=Radon Levels in Dwellings: Fact Sheet 4.6 |date=December 2009 |publisher=European Environment and Health Information System |access-date=2013-07-16 }}</ref> On 8 July 2010, the UK's Health Protection Agency issued new advice setting a "Target Level" of 100&nbsp;Bq/m<sup>3</sup> whilst retaining an "Action Level" of 200&nbsp;Bq/m<sup>3</sup>.<ref name="HPA radon">{{cite web |title=HPA issues new advice on radon |publisher=[[UK Health Protection Agency]] |date=July 2010 |url=http://www.hpa.org.uk/NewsCentre/NationalPressReleases/2010PressReleases/100708Newadviceonradon/ |archive-url=https://web.archive.org/web/20100714170654/http://www.hpa.org.uk/NewsCentre/NationalPressReleases/2010PressReleases/100708Newadviceonradon/ |url-status=dead |archive-date=2010-07-14 |access-date=2010-08-13}}</ref> Similar levels (as in the UK) are published by Norwegian Radiation and Nuclear Safety Authority (DSA)<ref>{{Cite web|title=Radon mitigation measures|url=https://dsa.no/en/radon/radon-mitigation-measures|access-date=2021-07-12|website=DSA|language=no}}</ref> with the maximum limit for schools, kindergartens, and new dwellings set at 200&nbsp;Bq/m<sup>3</sup>, where 100&nbsp;Bq/m<sup>3</sup> is set as the action level.<ref>{{Cite web|url=https://www2.dsa.no/publication/strategy-for-the-reduction-of-radon-exposure-in-norway.pdf|title=Strategy for the reduction of radon exposure in Norway, 2010|accessdate=14 March 2023|archive-date=20 November 2021|archive-url=https://web.archive.org/web/20211120103812/https://www.dsa.no/publication/strategy-for-the-reduction-of-radon-exposure-in-norway.pdf|url-status=dead}}</ref>

==== Inhalation and smoking ====
Results from epidemiological studies indicate that the risk of lung cancer increases with exposure to residential radon. A well known example of source of error is smoking, the main risk factor for lung cancer. In the US, cigarette smoking is estimated to cause 80% to 90% of all lung cancers.<ref>{{cite web |title=What Are the Risk Factors for Lung Cancer? |url=https://www.cdc.gov/cancer/lung/basic_info/risk_factors.htm |website=Centers for Disease Control and Prevention |access-date=3 May 2020 |date=18 September 2019}}</ref>

According to the EPA, the risk of lung cancer for smokers is significant due to [[Synergy|synergistic]] effects of radon and smoking. For this population about 62 people in a total of 1,000 will die of lung cancer compared to 7 people in a total of 1,000 for people who have never smoked.<ref name="epa" /> It cannot be excluded that the risk of non-smokers should be primarily explained by an effect of radon.

Radon, like other known or suspected external risk factors for lung cancer, is a threat for smokers and former smokers. This was demonstrated by the European pooling study.<ref name="bmj38308">{{cite journal |doi=10.1136/bmj.38308.477650.63 |pmid=15613366 |pmc=546066 |title=Radon in homes and risk of lung cancer: Collaborative analysis of individual data from 13 European case-control studies |journal=BMJ |volume=330 |issue=7485 |pages=223 |year=2005 |last1=Darby |first1=S. |last2=Hill |first2=D. |last3=Auvinen |first3=A. |last4=Barros-Dios |first4=J. M. |last5=Baysson |first5=H. |last6=Bochicchio |first6=F. |last7=Deo |first7=H. |last8=Falk |first8=R. |last9=Forastiere |first9=F. |last10=Hakama |first10=M. |last11=Heid |first11=I. |last12=Kreienbrock |first12=L. |last13=Kreuzer |first13=M. |last14=Lagarde |first14=F. |last15=Mäkeläinen |first15=I. |last16=Muirhead |first16=C. |last17=Oberaigner |first17=W. |last18=Pershagen |first18=G. |last19=Ruano-Ravina |first19=A. |last20=Ruosteenoja |first20=E. |last21=Rosario |first21=A. Schaffrath |last22=Tirmarche |first22=M. |last23=Tomášek |first23=L. |last24=Whitley |first24=E. |last25=Wichmann |first25=H.-E. |last26=Doll |first26=R. }}</ref> A commentary<ref name="bmj38308" /> to the pooling study stated: "it is not appropriate to talk simply of a risk from radon in homes. The risk is from smoking, compounded by a synergistic effect of radon for smokers. Without smoking, the effect seems to be so small as to be insignificant."

According to the European pooling study, there is a difference in risk for the [[Histology|histological]] subtypes of lung cancer and radon exposure. [[Small-cell lung carcinoma]], which has a high correlation with smoking, has a higher risk after radon exposure. For other histological subtypes such as [[adenocarcinoma]], the type that primarily affects non-smokers, the risk from radon appears to be lower.<ref name="bmj38308" /><ref>{{cite web |first=R. William |last=Field |location=Charleston, South Carolina |url=https://www.aarst.org/images/PCPanelRadonTest.pdf |title=President's Cancer Panel, Environmental Factors in Cancer: Radon |date=December 4, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20130829005508/http://www.aarst.org/images/PCPanelRadonTest.pdf |archive-date=August 29, 2013 |publisher=The American Association of Radon Scientists and Technologists (AARST)}}</ref>

A study of radiation from post-[[mastectomy]] [[radiotherapy]] shows that the simple models previously used to assess the combined and separate risks from radiation and smoking need to be developed.<ref>{{cite journal |last1=Kaufman |first1=E. L. |last2=Jacobson |first2=J. S. |last3=Hershman |first3=D. L. |last4=Desai |first4=M. |last5=Neugut |first5=A. I. |date=2008 |title=Effect of breast cancer radiotherapy and cigarette smoking on risk of second primary lung cancer |journal=[[Journal of Clinical Oncology]] |volume=26 |issue=3 |pages=392–398 |doi=10.1200/JCO.2007.13.3033 |pmid=18202415|doi-access=free }}</ref> This is also supported by new discussion about the calculation method, the [[linear no-threshold model]], which routinely has been used.<ref>{{cite journal |doi=10.1093/rpd/ncq141 |title=Review and evaluation of updated research on the health effects associated with low-dose ionising radiation |date=2010 |last1=Dauer |first1=L. T. |last2=Brooks |first2=A. L. |last3=Hoel |first3=D. G. |last4=Morgan |first4=W. F. |last5=Stram |first5=D. |last6=Tran |first6=P. |journal=[[Radiation Protection Dosimetry]] |volume=140 |issue=2 |pages=103–136 |pmid=20413418}}</ref>

A study from 2001, which included 436 non-smokers with lung cancer and a control group of 1649 non-smokers without lung cancer, showed that exposure to radon increased the risk of lung cancer in non-smokers. The group that had been exposed to tobacco smoke in the home appeared to have a much higher risk, while those who were not exposed to passive smoking did not show any increased risk with increasing radon exposure.<ref>{{cite journal |last1=Lagarde |first1=F. |last2=Axelsson |first2=G. |last3=Damber |first3=L. |last4=Mellander |first4=H. |last5=Nyberg |first5=F. |last6=Pershagen |first6=G. |date=2001 |title=Residential radon and lung cancer among never-smokers in Sweden |journal=Epidemiology |volume=12 |issue=4 |pages=396–404 |doi=10.1097/00001648-200107000-00009 |jstor=3703373 |pmid=11416777|s2cid=25719502 |doi-access=free }}</ref>

==== 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.