Editing Sievert (section)

==Health effects==
{{Further|Radiobiology}}
Ionizing radiation has [[deterministic]] and [[stochastic]] effects on human health. Deterministic (acute tissue effect) events happen with certainty, with the resulting health conditions occurring in every individual who received the same high dose. [[Stochastic]] (cancer induction and genetic) events are inherently [[random]], with most individuals in a group failing to ever exhibit any [[causal]] negative health effects after exposure, while an indeterministic random minority do, often with the resulting subtle negative health effects being observable only after large detailed [[epidemiology]] studies.

The use of the sievert implies that only stochastic effects are being considered, and to avoid confusion deterministic effects are conventionally compared to values of absorbed dose expressed by the SI unit gray (Gy).

===Stochastic effects===
Stochastic effects are those that occur randomly, such as [[radiation-induced cancer]]. The consensus of nuclear regulators, governments and the [[UNSCEAR]] is that the incidence of cancers due to ionizing radiation can be modeled as increasing linearly with [[effective dose (radiation)|effective dose]] at a rate of 5.5% per sievert.<ref name="ICRP103" /> This is known as the [[linear no-threshold model]] (LNT model). Some argue that this LNT model is now outdated and should be replaced with a threshold below which the body's natural cell processes repair damage and/or replace damaged cells.<ref>{{cite journal | last=Tubiana | first=Maurice | title=Dose–effect relationship and estimation of the carcinogenic effects of low doses of ionizing radiation: The joint report of the Académie des Sciences (Paris) and of the Académie Nationale de Médecine | journal=International Journal of Radiation Oncology, Biology, Physics | publisher=Elsevier BV | volume=63 | issue=2 | year=2005 | issn=0360-3016 | doi=10.1016/j.ijrobp.2005.06.013 | pages=317–319| pmid=16168825 | doi-access=free }}</ref><ref>{{cite book | last=Allison | first=Wade | title=Nuclear is for life: a cultural revolution | publisher=Wade Allison Publishing | publication-place=Aylesbury | year=2015 | isbn=978-0-9562756-4-6 | oclc=945569856}}</ref> There is general agreement that the risk is much higher for infants and fetuses than adults, higher for the middle-aged than for seniors, and higher for women than for men, though there is no quantitative consensus about this.<ref name="peck">{{cite web |last1=Peck |first1=Donald J. |title=How to Understand and Communicate Radiation Risk |url=http://www.imagewisely.org/Imaging-Professionals/Medical-Physicists/Articles/How-to-Understand-and-Communicate-Radiation-Risk.aspx |archive-url=https://web.archive.org/web/20101208060102/http://www.imagewisely.org/Imaging-Professionals/Medical-Physicists/Articles/How-to-Understand-and-Communicate-Radiation-Risk.aspx |url-status=dead |archive-date=8 December 2010 |publisher=Image Wisely |access-date=18 May 2012 |last2=Samei |first2=Ehsan }}</ref><ref name="UNSCEAR">{{cite book |author=United Nations Scientific Committee on the Effects of Atomic Radiation |title=Effects of ionizing radiation: UNSCEAR 2006 report to the General Assembly, with scientific annexes |year=2008 |publisher=United Nations |location=New York |isbn=978-92-1-142263-4 |url=http://www.unscear.org/unscear/en/publications.html |access-date=18 May 2012 }}</ref>

===Deterministic effects===
[[File:Effectofselfrepair.svg|thumb| This is a graph depicting the effect of [[dose fractionation]] on the ability of [[gamma rays]] to cause cell death. The blue line is for cells which were not given a chance to recover; the radiation was delivered in one session. The red line is for cells which were allowed to stand for a time and recover with the pause in delivery conferring [[radioresistance]].]]
The deterministic (acute tissue damage) effects that can lead to [[acute radiation syndrome]] only occur in the case of acute high doses (≳&nbsp;0.1&nbsp;Gy) and high dose rates (≳&nbsp;0.1&nbsp;Gy/h) and are conventionally not measured using the unit sievert, but use the unit gray (Gy).
A model of deterministic risk would require different weighting factors (not yet established) than are used in the calculation of equivalent and effective dose.

===ICRP dose limits===

The ICRP recommends a number of limits for dose uptake in table 8 of report 103. These limits are "situational", for planned, emergency and existing situations. Within these situations, limits are given for the following groups:<ref>{{cite journal|last1=ICRP|title=Report 103|pages=Table 8, section 6.5}}</ref>

* Planned exposure – limits given for occupational, medical and public 
* Emergency exposure – limits given for occupational and public exposure 
* Existing exposure – All persons exposed

For occupational exposure, the limit is 50&nbsp;mSv in a single year with a maximum of 100&nbsp;mSv in a consecutive five-year period, and for the public to an average of 1&nbsp;mSv (0.001&nbsp;Sv) of effective dose per year, not including medical and occupational exposures.<ref name="ICRP103" />

For comparison, natural radiation levels inside the [[United States Capitol]] are such that a human body would receive an additional dose rate of 0.85&nbsp;mSv/a, close to the regulatory limit, because of the uranium content of the [[granite]] structure.<ref name="FUSRAP">{{cite web |last=Formerly Utilized Sites Remedial Action Program |title=Radiation in the Environment |url=http://www.lrb.usace.army.mil/fusrap/docs/fusrap-fs-radenvironment-2008-09.pdf |publisher=US Army Corps of Engineers |access-date=18 May 2012 |archive-url=https://web.archive.org/web/20120211162419/http://www.lrb.usace.army.mil/fusrap/docs/fusrap-fs-radenvironment-2008-09.pdf |archive-date=11 February 2012 |url-status=dead}}</ref> According to the conservative ICRP model, someone who spent 20 years inside the capitol building would have an extra one in a thousand chance of getting cancer, over and above any other existing risk (calculated as: 20&nbsp;a·0.85&nbsp;mSv/a·0.001&nbsp;Sv/mSv·5.5%/Sv ≈ 0.1%). However, that "existing risk" is much higher; an average American would have a 10% chance of getting cancer during this same 20-year period, even without any exposure to artificial radiation (see natural [[Epidemiology of cancer]] and [[cancer rates]]).