View source for Sentinel species

{{Short description|Organisms used to detect risks to humans}}
{{hatnote|"Canary in a coal mine" redirects here. For the 1980 song by ''the Police'', see [[Zenyatta Mondatta]].}}

[[File:Canario amarillo.png|thumb|upright|[[Domestic canary]], historically used to detect gas in [[coal mines]]]]

'''Sentinel species''' are [[organism]]s, often animals, used to detect risks to humans by providing advance warning of a danger. The terms primarily apply in the context of environmental hazards rather than those from other sources. Some animals can act as sentinels because they may be more susceptible or have greater exposure to a particular hazard than humans in the same environment.<ref name="national research council">National Research Council (U.S.). Committee on Animals as Monitors of Environmental Hazards, "Animals as Sentinels of Environmental Health Hazards: Committee on Animals as Monitors of Environmental Hazards," National Academy Press: 1991, {{ISBN|0309040469}}.</ref> People have long observed animals for signs of impending hazards or evidence of environmental threats. Plants and other living organisms have also been used for these purposes.

== Historical examples ==
[[File:Strasbourg-16 rue du 22 Novembre (4).jpg|thumb|Miner with a canary in a cage|alt=Depiction of a miner with a canary in a cage]]

Many observations of animals point to toxicity in food, water or air that would or could harm humans.
=== Canaries ===
The classic example is the "[[domestic canary|canary]] in the [[Coal mining|coal mine]]". The idea of placing a warm-blooded animal in a mine to detect [[carbon monoxide]] was first proposed by [[John Scott Haldane]] in 1895,<ref>{{cite journal |author1= Haldane, John Scott |date=1895 |title=The Action of Carbonic Oxide on Man |journal=[[The Journal of Physiology]] |volume=XVIII |issue= 5–6|pages=448 |doi= 10.1113/jphysiol.1895.sp000578|pmid= 16992272|pmc= 1514663}}</ref> and canaries were used as early as 1896.<ref>{{cite journal |author1= Haldane, John Scott |date=1896 |title=The Detection and Estimation of Carbonic Oxide in Air |journal=[[The Journal of Physiology]] |volume=XX |issue= 6|pages=521–522 |doi= 10.1113/jphysiol.1896.sp000635|pmid= 16992351|pmc= 1512612}}</ref><ref name="acott">{{cite journal |last=Acott |first=C. |title=JS Haldane, JBS Haldane, L Hill, and A Siebe: A brief resume of their lives. |journal=South Pacific Underwater Medicine Society Journal |volume=29 |issue=3 |year=1999 |issn=0813-1988 |oclc=16986801 |url=http://archive.rubicon-foundation.org/6016 |archive-url=https://web.archive.org/web/20110727224432/http://archive.rubicon-foundation.org/6016 |url-status=usurped |archive-date=July 27, 2011 |access-date=2008-07-12 }}</ref><ref>{{cite journal |last1=Boycott |first1=A. E. |first2=G. C. C. |last2=Damant |first3=J. S. |last3=Haldane |title=Prevention of compressed air illness |journal=J. Hygiene |volume=8 |issue=3 |pages=342–443 |year=1908 |url=http://archive.rubicon-foundation.org/7489 |archive-url=https://web.archive.org/web/20080917041924/http://archive.rubicon-foundation.org/7489 |url-status=usurped |archive-date=September 17, 2008 |access-date=2013-09-05 |doi=10.1017/S0022172400003399 |pmc=2167126 |pmid=20474365}}</ref><ref>{{The Timetables of Science|pages=411}}</ref> Countries such as Britain, the United States, and Canada used canaries as a sentinel species.<ref>{{Cite web |last1=Magazine |first1=Smithsonian |last2=Eschner |first2=Kat |title=The Story of the Real Canary in the Coal Mine |url=https://www.smithsonianmag.com/smart-news/story-real-canary-coal-mine-180961570/ |access-date=2022-10-17 |website=Smithsonian Magazine |language=en}}</ref> Well into the 20th century, coal miners brought canaries into coal mines as an early-warning signal for toxic gases, primarily carbon monoxide.<ref>David A. Bengston, Diane S. Henshel, "Environmental Toxicology and Risk Assessment: Biomarkers and Risk Assessment", ASTM International, 1996, {{ISBN|0803120311}}, p 220.</ref> The birds, being more sensitive, would become sick before the miners, who would then have a chance to escape or put on protective [[respirators]]. In some cases, the canaries were kept in cages with dedicated oxygen tanks so the birds could survive after their illness provided a warning.<ref name="pollard">{{Cite web |last=Pollard |first=Lewis |date=2018-03-27 |title=The canary resuscitator |url=https://blog.scienceandindustrymuseum.org.uk/canary-resuscitator/ |access-date=2021-10-13 |website=Science and Industry Museum blog |language=en-GB}}</ref> "Canary in the coal mine" is now used as an idiom for a person or thing that warns people of danger.<ref>{{Cite web |last=ShareAmerica |date=2014-11-12 |title=Idiom in the news: Canary in the coal mine |url=https://share.america.gov/english-idiom-canary-coal-mine/ |access-date=2022-10-17 |website=ShareAmerica |language=en-US}}</ref><ref>{{Cite web |last=Forsaith |first=Carly |date=2022-09-22 |title='Canary in a Coal Mine': Definition, Meaning, and Examples |url=https://writingtips.org/canary-in-a-coal-mine/ |access-date=2022-10-17 |website=Writing Tips |language=en-US}}</ref>

=== Cats ===
In [[Minamata Bay]], Japan, [[Domestic cat|cats]] developed "[[Minamata disease|dancing cat fever]]" before humans were affected due to eating mercury-contaminated fish.<ref name="withrow">Stephen J. Withrow, David M. Vail, ''Withrow and MacEwen's Small Animal Clinical Oncology'', Elsevier: 2007, {{ISBN|0721605583}}, p. 73-4.</ref> 

=== Dogs ===
Dogs were recognized as early as 1939 to be more susceptible to tonsil cancer if they were kept in crowded urban environments.<ref name="withrow" /> Studies similarly found higher disease rates in animals exposed to [[tobacco smoke]].<ref name="withrow" /> 
===Poultry===
[[Yushō disease]] was discovered when poultry began dying at alarming rates due to [[polychlorinated biphenyl]] (PCB) poisoning, although not before approximately 14,000 people were affected.

== Characteristics ==
Animal sentinels must have measurable responses to the hazard in question, whether that is due to the animal's death, disappearance, or some other determinable aspect.<ref name="national research council" />{{rp|34}} Many of these species are ideally [[Endangered species|unendangered]] and easy to handle. It is important that the species' range overlap with the range being studied.<ref name="bds" /> Often the ideal species is determined by the characteristics of the hazard.

For example, [[honey bee]]s are susceptible to [[air pollution]].<ref name="national research council" />{{rp|35}} Similarly both [[bats]] and [[swallows]] have been used to monitor pesticide contamination due to their diet of insects that may have been affected by the chemicals.<ref name="national research council" />{{rp|35}} By the same token, aquatic animals, or their direct predators, are used as sentinel species to monitor [[water pollution]].<ref>{{Cite web |title=Sentinel Species - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/immunology-and-microbiology/sentinel-species |access-date=2023-05-13 |website=www.sciencedirect.com}}</ref>

Some species may show effects of a contaminant before humans due to their size, their reproductive rate, or their increased exposure to the contaminant.<ref name="bds">Arthur D. Bloom, Frederick de Serres, ''Ecotoxicity and Human Health: A Biological Approach to Environmental Remediation'', CRC Press: 1995, {{ISBN|1566701414}}, page 76.</ref>

== Specific applications ==

=== Toxic gases ===
[[File:Canary coal mine.jpg|thumb| Mining foreman R. Thornburg shows a small cage with a canary used for testing carbon monoxide gas in 1928.]]
Canaries were iconically used in [[coal mines]] to detect the presence of [[carbon monoxide]]. The bird's rapid breathing rate, small size, and high metabolism, compared to the miners, led birds in dangerous mines to succumb before the miners, thereby giving the miners time to take action.

=== Air and water pollution ===
A number of animals have been used to measure varying kinds of air pollution. These include [[honey bee]]s for air pollution, [[bivalve molluscs]]<ref>{{Cite web |url=http://molluscan-eye.epoc.u-bordeaux1.fr/index.php?rubrique=accueil&lang=en |title=Molluscan eye |access-date=2014-01-25 |archive-date=2016-11-13 |archive-url=https://web.archive.org/web/20161113173444/http://molluscan-eye.epoc.u-bordeaux1.fr/index.php?rubrique=accueil&lang=en |url-status=dead }}</ref> for online water-quality survey and [[pigeon]]s for atmospheric lead.<ref name="national research council" />{{rp|35}} Bats and swallows have been used to monitor pesticide contamination due to their diet of insects that may have been affected by the chemicals.<ref name="national research council" />{{rp|35}}

Aquatic [[DDT]] pollution has been quantitatively measured in [[California]] fish. [[Polychlorinated biphenyl|PCB]] has been measured through the analysis of fish livers.<ref name="national research council" />{{rp|82}} [[Toxaphene]] concentrations were discovered far from the area of its use through analysis of [[trout]] in the [[Great Lakes]].<ref name="national research council" />{{rp|85}} The evidence of atmospheric transport of the substance influenced the subsequent prohibition of its widespread use. [[Alligators]] may have been used to warn of hazardous contamination in [[Centreville, Mississippi]] retention ponds.<ref>{{Citation |author=Eugene Love Fair Jr. |date=May 28, 2013 |title=Christmas v. Exxon Mobil |work= [[Mississippi Court of Appeals]] |url=https://caselaw.findlaw.com/ms-court-of-appeals/1632483.html |access-date=January 3, 2014}}</ref>

Scientists also monitor [[crayfish]] in the wild in natural bodies of water to study the levels of pollutants there.<ref name="Brewery" /><ref name="Missouri">{{cite magazine|url=https://mdc.mo.gov/conmag/2008/11/clean-water|title=Clean Water|magazine=Missouri Conservationist Magazine|publisher=Missouri Department of Conservation|date=November 2008|volume=69|issue=11|access-date=1 November 2019}}</ref><ref name="Meuse">{{Cite journal | first1 = P. A. E. L. | last1 = Schilderman | first2= E. J. C. |last2=Moonen|first3=L. M.|last3=Maas|first4=I.|last4=Welle|first5=J. C. S.|last5=Kleinjans | year=1999 | title = Use of Crayfish in Biomonitoring Studies of Environmental Pollution of the River Meuse | journal = Ecotoxicology and Environmental Safety | volume = 44 | issue = 3 | pages = 241–252 | doi =10.1006/eesa.1999.1827 | pmid = 10581118 | issn = 0147-6513}}</ref>

The Protivin brewery in the [[Czech Republic]] uses crayfish outfitted with sensors to detect any changes in their bodies or pulse activity in order to monitor the purity of the water used in their product. The creatures are kept in a fish tank that is fed with the same local natural source water used in their brewing. If three or more of the crayfish have changes to their pulses, employees know there is a change in the water and examine the parameters.<ref name="Brewery">{{cite news|url=https://www.reuters.com/article/us-czech-crayfish-water-purity/crayfish-staff-help-czech-brewery-keep-its-water-as-pure-as-can-be-idUSKCN1C22GP|archive-url=https://web.archive.org/web/20191025221438/https://www.reuters.com/article/us-czech-crayfish-water-purity/crayfish-staff-help-czech-brewery-keep-its-water-as-pure-as-can-be-idUSKCN1C22GP|title=Crayfish staff help Czech brewery keep its water as pure as can be|work=[[Reuters TV]]|last=Hanrahan|first=Mark|date=27 September 2017|archive-date=25 October 2019|access-date=1 November 2019}}</ref>

=== Infectious diseases ===
The discovery of [[West Nile virus]] in the Western Hemisphere was heralded by an outbreak of disease in crows and other wild birds. Other emerging diseases have demonstrated linkages between animal health events and human risk, including [[monkeypox]], [[SARS]], and [[avian influenza]]. In outbreaks of bubonic plague, rats begin dying out before humans. {{citation needed|date=October 2021}}

=== Household toxins ===
[[Dog]]s may provide early warning of [[lead poisoning]] hazards in a [[home]], and certain cancers in dogs and [[cat]]s have been linked to household exposures to [[pesticide]]s, [[cigarette]] smoke, and other [[carcinogens]]. {{citation needed|date=October 2021}}

==Cultural references==
* [[Kurt Vonnegut]] in an interview compared the function of artists in human society to coal-mine canaries; see [[:q:Kurt Vonnegut|Wikiquote]].<ref>Interview "Physicist, Purge Thyself" in the Chicago Tribune Magazine (22 June 1969)</ref>
* "Canary in a Coalmine" is the title of a non-single track on [[The Police]]'s 1980 album [[Zenyatta Mondatta]].<ref>{{Cite web |title=Christmas Day lost and found: Police's 'Canary in a Coalmine' |url=https://www.tampabay.com/archive/2013/12/25/christmas-day-lost-and-found-police-s-canary-in-a-coalmine/ |access-date=2022-10-17 |website=Tampa Bay Times |language=en}}</ref>
* "Canary in a Coalmine" is the title of a non-single track on [[The Crane Wives]]’ 2012 album [https://www.thecranewives.com/music-fool The Fool in Her Wedding Gown]

== See also ==
* [[Guard dog]]
* [[Indicator species]]
* [[Stack canary]]
* [[Warrant canary]]

== References ==
{{reflist|30em}}

==Further reading==
* {{cite journal
 |author1=van der Schalie WH |author2=Gardner HS Jr |author3=Bantle JA |author4=De Rosa CT |author5=Finch RA |author6=Reif JS |author7=Reuter RH |author8=Backer LC |author9=Burger J |author10=Folmar LC |author11=Stokes WS. | title = Animals as sentinels of human health hazards of environmental chemicals | journal = [[Environ Health Perspect]] |date=Apr 1999 | volume = 107 | issue = 4 | pages = 309–315 | doi=10.1289/ehp.99107309 |pmid=10090711 |pmc=1566523 }}
* {{cite journal |author1=O'Brien DJ |author2=Kaneene JB |author3=Poppenga RH | title = The use of mammals as sentinels for human exposure to toxic contaminants in the environment | journal = Environ Health Perspect |date=Mar 1993 | volume = 99 | pages = 351–368 | pmid = 8319652 | pmc=1567056 | doi=10.1289/ehp.9399351 }}
* {{cite journal |author1=Backer LC |author2=Grindem CB |author3=Corbett WT |author4=Cullins L |author5=Hunter JL | title = Pet dogs as sentinels for environmental contamination | journal = Sci Total Environ | date  = 2001-07-02 | volume = 274 | issue = 1–3 | pages = 161–169 | doi  = 10.1016/S0048-9697(01)00740-9 |pmid=11453293 |bibcode=2001ScTEn.274..161B |url=https://zenodo.org/record/1259733 }}
* {{cite journal |author1=Rabinowitz P |author2=Gordon Z |author3=Chudnov D |author4=Wilcox M |author5=Odofin L |author6=Liu A |author7=Dein J. | title = Animals as sentinels of bioterrorism agents | journal = Emerg Infect Dis |date=Apr 2006 | volume = 12 | issue = 4 | pages = 647–652 | pmid = 16704814 | doi=10.3201/eid1204.051120 | pmc=3294700}}
* {{cite journal |author1=Meselson M |author2=Guillemin J |author3=Hugh-Jones M |author4=Langmuir A |author5=Popova I |author6=Shelokov A |author7=Yampolskaya O | title = The Sverdlovsk anthrax outbreak of 1979 | journal = [[Science (journal)|Science]] | date = 1994-11-18 | volume = 266 | issue = 5188 | pages = 1202–1208 | pmid = 7973702 | doi  = 10.1126/science.7973702 |bibcode=1994Sci...266.1202M }}
* {{cite journal | author = Kahn LH | title = Confronting zoonoses, linking human and veterinary medicine
 | journal = Emerg Infect Dis |date=Apr 2006 | volume = 12 | issue = 4 | pages = 556–561 | doi=10.3201/eid1204.050956 | pmid = 16704801
 | pmc = 3294691 }}

== External links ==
* [http://canarydatabase.org The Canary Database: Animals As Sentinels of Human Environmental Health Hazards]
* Online biomonitoring of water quality by a permanent record of bivalve molluscs' behavior and physiology (biological rhythms, growth rate, spawning, early warning), 24/7, worldwide: the [http://molluscan-eye.epoc.u-bordeaux1.fr/index.php?rubrique=accueil&lang=en MolluSCAN ''eye''] project

[[Category:Environmental conservation]]
[[Category:Mine safety]]