Table Of ContentVolume 4: s-z; Appendices; Index
EDITORS AND
CONSULTANTS
EDITOR IN CHIEF Eric Cohen Helen Nissenbaum
Carl Mitcham Ethicsand Public PolicyCenter Associate Professor, Cultureand Com-
munication,Computer Science, New
Professor, Liberal ArtsandInternational Stephen H. Cutcliffe
YorkUniversity
Studies, ColoradoSchool ofMines; Professor,History; Professor and Chair,
Faculty Affiliate,Center forScienceand Science, Technology, and SocietyPro- Roger A. Pielke, Jr.
Technology Policy gram,Lehigh University Professor, Environmental Studies;
Research, University ofColorado, Director, Center forScience andTech-
Paul T. Durbin
Boulder nology Policy Research,University of
Professor Emeritus,Philosophy, Univer-
Colorado, Boulder
sityofDelaware
ASSOCIATE EDITORS
Michael Ruse
Deni Elliott
Larry Arnhart LucyleT. Werkmeister Professor of
Poynter Jamison ChairinMedia Ethics
Professor, Political Science,Northern Philosophy, Florida StateUniversity
andPressPolicy, University ofSouth
Illinois University
Florida Daniel Sarewitz
Deborah G. Johnson Professor,ScienceandSociety;Director,
Franz Allen Foltz
Anne Shirley Carter OlssonProfessor of Consortium for Science, Policy,and
Associate Professor, Science, Technol-
Applied Ethics andChair, Science, Outcomes, Arizona StateUniversity
ogy, andSociety, Rochester Institute of
Technology, andSociety, University of A. George Schillinger
Technology
Virginia
Professor Emeritus, Management, Poly-
Robert Frodeman
Raymond E. Spier technicUniversity, Brooklyn
Associate Professor andChair, Philo-
Emeritus Professor, Scienceand Engi- Paul B. Thompson
sophyandReligionStudies,Universityof
neering Ethics, University ofSurrey
North Texas W.K.Kellogg Professor ofAgricultural,
Foodand CommunityEthics, Michigan
SPECIAL EDITORIAL Francis Fukuyama
StateUniversity
CONSULTANT Bernard L.Schwartz Professor in Inter-
Nancy Tuana
national Political Economy, Johns Hop-
Stephanie J. Bird Professor, Philosophy; Director, Rock
kins University
Editor, Scienceand Engineering Ethics EthicsInstitute, Pennsylvania State
Rachelle Hollander
University
CONSULTANTS Baltimore, Maryland
Vivian Weil
Robert H. Blank Sheldon Krimsky Professor, Ethics; Director, Centerfor
Professor, Public Policy, Brunel Professor,Urban andEnvironmental the Study ofEthicsin the Professions,
University Policyand Planning, Tufts University Illinois Institute ofTechnology
George Bugliarello Jose´ Antonio Lo´pez Cerezo Caroline Whitbeck
Professor,CivilEngineering;Chancellor, Professor,Philosophy ofScience, Uni- Elmer G.Beamer–HubertH.Schneider
Polytechnic University, Brooklyn versityofOviedo, Spain Professor inEthics, Case Western Re-
Ruth Chadwick Valerie Mike´ serve University
Professor, InstituteofEnvironment, ClinicalProfessor, Public Health, John Ziman
Philosophy, andPublic Policy, Lancaster WeillMedicalCollege ofCornell Emeritus Professor, Physics, Bristol
University, UK University University (dec.)
ii
EDITED BY
CARL MITCHAM
volume
4
s–z
appendices
index
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Encyclopediaof Science,Technology,andEthics
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S
SAFETY ENGINEERING theywereacceptedbyworkersandthepublicasaneces-
saryconcomitanttotechnologicalprogress.
(cid:1)(cid:1)(cid:1)
However,overthecourseofthenineteenthcentury
HistoricalEmergence
the protection of human safety became an increasingly
Practices
important priority for engineers, companies, and even-
tually federal and state governments. Indeed, the first
HISTORICAL EMERGENCE scientificresearchcontractfromthefederalgovernment
was issued to the Franklin Institute in Philadelphia in
The protection of people from harm increasingly has
1830toinvestigatethecausesofsteamboatboilerexplo-
been a focus of many fields of engineering since the
sionsandtoproposesolutions(Burke1966).
nineteenthcentury.AtthedawnoftheIndustrialRevo-
lution (c. 1750–1850) engineers, as the term is used As each new technology matured to the point
today, devoted their efforts almost entirely to making where advances in performance were incremental, a
devicesthatfunctionedreliablyandprofitably,butwith poor safety record became a barrier to increased public
littleattentiontosafety.OnenotableexceptionisJames acceptance and use. Workers began to organize into
Watt (1736–1819), the so-called inventor of the steam unions and insist that they be better protected from
engine.Despiteintroducingnumerousimprovementson workplacehazards.Engineeringsocieties,whoseoriginal
the Newcomen steam engine, Watt intentionally charters tended to stress the promotion and facilitation
resisted building a high-pressure engine because of the of the profession(cid:1)s work, by the mid-twentieth century
dangers it posed to those working with it. In fact, when began to impose safety as a primary ethical duty of the
Richard Trevithick (1771–1833) began experiments engineer. The end of the nineteenth century also wit-
with the high-pressure steam engine, which increased nessed the development of safety codes and standards
both efficiency and power, Watt (and his partner Mat- governing the use of natural gas and electricity, the
thewBoulton)petitionedParliamenttopassanactout- design of building and steam boilers, and the storage
lawingtheuseofsuchenginesasapublicdanger. anduseofexplosives.
The second generation masters of steam power for Inthetwenty-firstcenturynearlyeveryengineering
railroadsandsteamboatsthusbroughtwiththemboiler codeofethicsstressesthesafetyofworkersandthepub-
explosions, brakeman maimings, and wrecks causing lic. The American Nuclear Society(cid:1)s Code of Ethics
astonishing loss of life. In Life on the Mississippi (1883) (2003)states:
and again in Huckleberry Finn (1894) Mark Twain
We hold paramount the safety, health, and wel-
described in vivid detail the explosion of steam ships
fareofthepublicandfellowworkers,worktopro-
andthe resultant deathandinjuryofpassengers. Manu- tect the environment, and strive to comply with
factories too subjected workers (and often those living the principles of sustainable development in the
nearby) to industrial accidents, toxic fumes, and loss of performance of our professional duties. The first
hearing. Although those risks were hardly unknown, commitment in the Code of Ethics for the Insti-
1673
SAFETYENGINEERING
tute of Electrical and Electronic Engineers man- SEEALSO EngineeringEthics;SafetyFactors.
dates that members ... accept responsibility in
makingengineering decisionsconsistentwiththe BIBLIOGRAPHY
safety, health and welfare of the public, and to
Burke, John G. (1966). ‘‘Bursting Boilers and the Federal
disclosepromptlyfactorsthatmightendangerthe Power.’’ Technology and Culture 7:1(1–23). A widely rep-
public or theenvironment(InstituteofElectrical rinted article. For critical comment, see Richard N. Lan-
andElectronicEngineers1990). glois, David J. Denault, and Samson M. Kimenyi, ‘‘Burst-
ing Boilers and the Federal Power Redux: The Evolution
All licensed professional engineers are bound by of Safety on the Western Waters,’’ University of Connecti-
the Code of Ethics for Engineers promulgated by the cut Department of Economics Working Papers Series (May
1994).
NationalSocietyofProfessionalEngineers.BothFunda-
mental Canon No. 1 and the first Rule of Practice Joyce,MalcolmJ.,andDerekW.Seward.(2002).‘‘Innovative
M.Sc. in Safety Engineering—A Model for Industry-Based
impose on the engineer a duty to ‘‘hold paramount the
Courses in the 21st Century?’’ Engineering Education 2002:
safety, health and welfare of the public’’ (National
ProfessionalEngineeringScenarios2002/056:(2:28/6).
SocietyofProfessionalEngineers2003).
INTERNETRESOURCES
Apart from these commitments by long-standing
communities of engineers there are many engineers American Nuclear Society. Code of Ethics. (2003). Avail-
ableatwww.ans.org.
whose work is devoted entirely to the protection of the
AmericanSocietyofSafetyEngineers.(2004).VisionState-
public and workers from the hazards of technology and
ment.Availableatwww.asse.org.
natural phenomena: Fire protection engineering, auto-
Institute of Electrical and Electronic Engineers. Code of
mobile safety engineering, and industrial safety engi-
Ethics.(1990).Availableatwww.ieee.org.
neering are a few examples. Safety engineering is itself
National Society of Professional Engineers. Code of Ethics.
an engineering discipline; its practitioners attempt to
(2003).Availableatwww.nspe.org.
understandthewaysinwhichtechnologicalsystemsfail
and discover ways to prevent such failures. The Ameri-
can Society of Safety Engineers, founded in 1911 and PRACTICES
now numbering over 30,000 members, is devoted to
Safety is one of the primary goals of engineering. In
being ‘‘the premier organization and resource for those
most ethical codes for engineers safety is mentioned as
engaged in the practice of protecting people, property
an essential area of professional competence and
and the environment, and to lead the profession glob-
responsibility.
ally’’(AmericanSocietyofSafetyEngineers2004).
In everyday language, the term safety is often used
Theintertwiningofengineeringandsafetyprobably
todenoteabsolutesafety,thatis,certaintythataccidents
willintensifyinthefutureinresponsetoconstantlyris-
or other harms will not occur. In engineering practice,
ing public expectations. Two prominent engineering
safetyisanidealthatcanbeapproached,butneverfully
scholars in Lancaster University(cid:1)s Department of Engi-
attained. What can be achieved is relative safety, mean-
neering have observed the large gap between the safety
ing that it is unlikely but not impossible that harm will
expectations of today and those in the early days of
occur. The safety requirements in regulations and stan-
moderntechnologies:
dards represent different (and mostly high) levels of
Safety is rapidly becoming a means by which the relative safety. Industries with high safety ambitions,
public and governments judge the viability of such as airway traffic, are characterized by continuous
organisationsinvolvedinsafety-related processes, endeavorstoimprovethelevelofsafety.
possiblymoresothanenvironmentalissues.Many
large organisations could not afford a single, Theambiguitybetweenabsoluteandrelative safety
large-scaleincidentasaresultofaninferiorsafety is a common cause of misunderstandings between
culture, despite buoyant economics. This is a sig- experts and the public. Both concepts are useful, but it
nificant dynamic departure from past public isessentialtodistinguishbetweenthem.
acceptabilityoffatalincidents(JoyceandSeward
In decision theory, lack of knowledge is divided
2004).
into the two major categories: ‘‘risk’’and ‘‘uncertainty.’’
The dedication of the engineering profession to
Indecision-makingunderrisk,theprobabilitiesofpossi-
safety as a primary goal and an ethical duty is in accor-
ble outcomes are known, whereas in decision-making
dancewiththischangeinpublicexpectations.
under uncertainty, probabilities are either unknown or
WILLIAM M. SHIELDS known with insufficient precision. In engineering prac-
1674 EncyclopediaofScience,Technology,andEthics
SAFETYFACTORS
tice, both risk and uncertainty have to be taken into tions or pieces of equipment that were originally in
account. Even when engineers have a good estimate of excellent shape. Regular inspections by persons with
the probability (risk) of failure, some uncertainty sufficient competence and mandate are an efficient
remainsaboutthecorrectnessofthisestimate. meanstopreventthisfromhappening.
Safety has often been defined as the antonym of
Educated and responsible operators. Human mistakes
risk, but that is only part of the truth. In order to
areanimportantsourceofaccidents.Anefficientcoun-
achievesafetyinpracticalapplications,thedangersthat
termeasureistoeducateworkers,authorizethemtotem-
originate in uncertainty are equally important to elimi-
porarily stop processes they consider to be acutely dan-
nateorreduceasthosethatcanbeexpressedintermsof
gerous, and encourage them to take initiatives to
risk. Many safety measures in engineering are taken to
improvesafety.
diminish the damages that would follow from possible
unknown sources of failures. Such measures protect Incidence reporting. Experience from air traffic and
againstuncertaintyratherthanrisk. nuclearenergyshowsthatsystemsforreportingandana-
lyzing safety incidents are an efficientmeansto prevent
Several methods are used by engineers to achieve
accidents. Systems for anonymous reporting facilitate
safetyinthedesignandoperationofpotentiallydanger-
thereportingofhumanmistakes.
oustechnology.
Inherently safe design. The first step in safety engi- Safety management. Safety can be achieved only in
neering should always be to minimize the inherent dan- anorganizationwhosetopmanagementgivespriorityto
gersintheprocessasfaraspossible.Dangeroussubstances safetyandaimsatcontinuousimprovement.
orreactionscanbereplacedbylessdangerousones.Fire-
proofmaterialscanbeusedinsteadofflammableones.In SVEN OVE HANSSON
somecases,temperatureorpressurecanbereduced.
Safety reserves. Constructions should be strong
SEE ALSO Airplanes; Automobiles; Aviation Regulatory
enough to resist loads and disturbances exceeding those Agencies; Building Destruction and Collapse; Engineering
that are intended. In most cases, the best way to obtain Ethics; Fire; Regulatory Toxicology; Robot Toys; Safety
sufficient safety reserves is to employ explicitly chosen Factors.
safetyfactors.
BIBLIOGRAPHY
Negativefeedback.Dangerousoperationsshouldhave
negative feedback mechanisms that lead to a self-shut- Marshall, Gilbert. (2000). Safety Engineering, 3rd edition.
Des Plaines, IL: American Society of Safety Engineers.
downincriticalaccidentsituationsorwhentheoperator
General safety principles and their application on indus-
losescontrol.Twoclassicalexamplesarethesafetyvalve
trialworkplaces.
that lets out steam when the pressure becomes too high
inasteamboilerandthe‘‘deadman(cid:1)shandle’’thatstops
the train when the driver falls asleep. One of the most
SAFETY FACTORS
important safety measures inthe nuclear energyindustry
istoensurethata nuclearreactorclosesdownautomati- (cid:1)(cid:1)(cid:1)
callywhenameltdownapproaches.
A safety factor (also called an uncertainty factor or
Multiple independent safety barriers. In order to avert assessment factor) is a number by which some variable
serious dangers, a chain of barriers is needed, each of such as load or dose is multiplied or divided in order to
which is independent of its predecessors so that if the increase safety. Safety factors are used in engineering
firstfails,thenthesecondisstillintact,andsoon.Typi- design,toxicology,andotherdisciplinestoavoidvarious
cally the first barriers are measures to prevent an acci- typesoffailure.
dent, after which follow barriers that limit the conse-
The sources of failure that safety factors are
quencesofanaccident,andfinallyrescueservicesasthe
intended to protect against can be divided into two
lastresort.OneofthemajorlessonsfromtheTitanicdis-
major categories: (a) the variability of conditions that
aster(1912)isthatanimprovementoftheearlybarriers
influence the risk of failure, such as variations in the
is no excuse for reducing the later barriers (such as
strength of steel and in the sensitivity of humans to
accesstolifeboats).
toxic substances, and (b) the uncertainty of human
Maintenance and inspections. Many severe accidents knowledge, including the possibility that the models
have resulted from insufficient maintenance of installa- usedforriskassessmentmaybeinaccurate.
EncyclopediaofScience,Technology,andEthics 1675
SAKHAROV,ANDREI
Safety factors are used to obtain a safety reserve, a tionship), then the risk reduction will be proportionate
margin between actual conditions andthose that would to the safety factor. If the dose–response relationship is
lead to failure. Safety reserves can also be obtained nonlinear,thenthereductioninriskcanbeeithermore
withouttheuseofexplicitlychosensafetyfactors. or less than proportionate. Because the dose–response
relationship at very low doses is always unknown, the
At least since antiquity, builders have obtained
exact effect of using a safety factor cannot be known
safety reserves by adding extra strength to their con-
withcertainty.
structions.The earliest knownuse ofexplicit safety fac-
tors in engineering dates from the 1860s. In modern Natural organisms often have safety reserves that
engineering, safety factors are used to compensate for can be described in terms of safety factors. Structural
fivetypesoffailure: safety factors have been calculated for mammalian
bones,crabclaws,shellsoflimpets,andtreestems.Nat-
(1) higherloadsthanthoseforeseen,
uralsafetyreservesmaketheorganismbetterabletosur-
(2) worsepropertiesofthematerialthanforeseen, vive unusual conditions. Hence, the extra strength of
(3) imperfect theory of the failure mechanism in tree stems makes it possible for them to withstand
question, storms even if they have been damaged by insects. But
safety reserves also have their costs. Trees with large
(4) possiblyunknownfailuremechanisms,and
safetyreservesarebetterabletoresiststorms,butinthe
(5) humanerrorindesignorcalculations.
competition for light reception, they may lose out to
Thefirsttwoofthesecaningeneralbeclassifiedasvari- tenderandhightreeswithsmallersafetyreserves.
abilities,whereasthelastthreebelongtothecategoryof
At least two important lessons can learned from
(genuine)uncertainty.
nature in this context. First, resistance to unusual loads
In order to be an efficient guide for safe design, isessentialforsurvival.Second,abalancewillneverthe-
safety factors should be applied to all the integrity- less always have to be struck between the dangers of
threatening mechanisms that can occur. For instance, havingtoolittlereservecapacityandthecostsofhaving
onesafetyfactormayberequiredforresistancetoplastic an unused reserve capacity. Perfect safety cannot be
deformation and anotherfor fatigueresistance. Asafety obtained,butachosenbalancebetweensafetyandcosts
factor is mostcommonly expressed as the ratio between can be implemented with the help of safety factors and
ameasureofthemaximalloadnotleadingtothespeci- otherregulationinstruments.
fied type of failure and a corresponding measure of the
applied load. In some cases it may be preferable to SVEN OVE HANSSON
express the safety factor as the ratio between the esti-
mateddesignlifeandtheactualservicelife.
SEE ALSO BioengineeringEthics;EngineeringEthics;Safety
The use of explicit safety factors in regulatory toxi- Engineering.
cology dates from the middle of the twentieth century.
In 1954 Arnold J. Lehman and O. Garth Fitzhugh, two BIBLIOGRAPHY
U.S. Food and Drug Administration (FDA) toxicolo-
Dourson,MichaelL.,andJerryF.Stara.(1983).‘‘Regulatory
gists, proposed that ADIs (acceptable daily intakes) for HistoryandExperimentalSupportofUncertainty(Safety)
food additives be obtained by dividing the lowest dose Factors.’’ Regulatory Toxicology and Pharmacology 3(3):
causing no harm in experimental animals (counted per 224–238.Safetyfactorsintoxicology.
kilogram body weight) by 100. This value of 100 is still Randall, F. A. (1976). ‘‘The Safety Factor of Structures in
widely used. It is now often accounted for as being the History.’’ProfessionalSafety,January:12–28.Safetyfactors
inengineeringdesign.
product of two subfactors: one factor of 10 for interspe-
cies (animal to human) variability in response to the
toxicity and another factor of 10 for intraspecies
(human) variability in the same respect. Higher safety
factorssuchas1,000,2,000,andeven5,000canbeused
SAKHAROV, ANDREI
intheregulationofsubstancesbelievedtoinducesevere
toxiceffectsinhumans. (cid:1)(cid:1)(cid:1)
The effect of a safety factor on the actual risk Theoretical physicist and the ‘‘father of the Soviet H-
dependsonthe dose–responserelationship. Ifthe riskis bomb,’’AndreiSakharov(1921–1989),whowasbornin
proportionate to the dose (linear dose–response rela- Moscow on May 21, became a prominent human rights
1676 EncyclopediaofScience,Technology,andEthics
