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Risk AssessmentRisk Assessment

Acceptable Risk

Time for SH&E professionals to adopt the concept By Fred A. Manuele

THETERMACCEPTABLERISK is frequently used in standards and guidelines throughout the world, yet a substantial percentage of those with SH&E respon- sibilities are reluctant to adopt or use it. Evidence of this reluctance often arises in discussions surround- ing the development of new or revised standards or technical reports. The aversion may derive from: •a lack of awareness of the nature of risk; •concern over the subjective judgments made

and the uncertainties that almost always exist when risks are assessed; •the lack of in-depth statistical probability and

severity data that allows precise and numerically accurate risk assessments; •insufficient real-world experience in more haz-

ardous environments where nontrivial risks are nec- essarily accepted every day. However, in recent years, the concept of accept-

able risk has been interwoven into international standards and guidelines for a broad range of equip- ment, products, processes and systems. This has occurred in recognition of the fact that risk-related decisions are made constantly in real-world applica- tions and that society benefits if those decisions

achieve acceptable risk levels. This primer is designed to

help readers gain an under- standing of risk and the con- cept of acceptable risk. The far-reaching premise presented is fundamental in dealing with risk. Several examples of the use of the term acceptable risk as taken from the applicable lit- erature. Discussions address the impossibility of achieving zero risk levels, the inadequacy of minimum risk as a replace- ment term for acceptable risk, and the shortcomings that may result from designing only to a

standard’s requirements. Finally, the “as low as rea- sonably practicable (ALARP) concept” is presented with an example of how it is applied in achieving an acceptable risk level.

Fundamental Premise The following general, all-encompassing premise

is basic to the work of all personnel who give coun- sel to prevent injury, illness and damage to property and the environment. The entirety of purpose of those responsible for safety, regardless of their titles, is to identi- fy, evaluate, and eliminate or control hazards so that the risks deriving from those hazards are acceptable. That premise is supported by this theory: If there

are no hazards, if there is no potential for harm, risks of injury or damage cannot arise. If there were no risks, there would be no need for SH&E profession- als. (Note: For simplicity, the terms hazard, risk and safety apply to all hazard-related incidents or expo- sures that could cause injury or illness, or damage property or the environment.)

Use of the Term Acceptable Risk The more frequent use over time of the term

acceptable risk in standards and guidelines is notable, as the following citations show. SH&E per- sonnel reluctant to adopt the concept implied by the term should consider the breadth and implication of this evolution. The term acceptable risk is becoming the norm. The following (intentionally lengthy) list of citations shows how broadly the concept of acceptable risk has been adopted. 1) Lowrance (1976) wrote, “A thing is safe if its

risks are judged to be acceptable.” 2) The following citation, from a 1980 court deci-

sion, is significant because it has given long-term guidance with respect to Department of Labor poli- cy and to the work performed by NIOSH.

Fred A. Manuele, P.E., CSP, is president of Hazards Limited, which he formed after retiring

from Marsh & McLennan where he was a managing director and manager of M&M Protection Consultants. He is the author of several books, including Advanced Safety

Management: Focusing on Z10 and Serious Injury Prevention, On the Practice of Safety, Innovations

in Safety Management: Addressing Career Knowledge Needs and Heinrich Revisited: Truisms

or Myths.Manuele was also coeditor of Safety Through Design. He is an ASSE Fellow, a

professional member of the Northeastern Illinois Chapter and a member of the Engineering

Practice Specialty. He is a former board member of ASSE, BCSP and National Safety Council.

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3) International Organization for Standardization (ISO) and International Electrotechnical Commis- sion (IEC) (1990) issued guidelines for including safety aspects in standards. These guidelines pro- vide standardized terms and definitions to be used in standards for “any safety aspect related to people, property or the environment.” The second edition, issued in 1999, contains the following definitions:

Safety: freedom from unacceptable risk (3.1). Tolerable risk: risk which is accepted in a given

context based on the current values of society (3.7). 4) Fewtrell and Bartram (2001), in a document for

World Health Organization, address standards relat- ed to water quality. They offer the following guide- lines for determining acceptable risk.

Arisk is acceptablewhen: it falls below an arbi- trary defined probability; it falls below some level that is already tolerated; it falls below an arbitrary defined attributable fraction of total disease burden in the community; the cost of reducing the risk would exceed the costs saved; the cost of reducing the risk would exceed the costs saved when the “costs of suf- fering” are also factored in; the opportunity costs would be better spent on other, more pressing, public health problems; public health professionals say it is acceptable; the general public say it is acceptable (or more likely, do not say it is not); politicians say it is acceptable.

5) OSHA (2003) set forth requirements for organ- izations seeking certification under the agency’s Vol- untary Protection Programs (VPP):

The Supreme Court’s benzene decision of 1980 states that “before he can promulgate any per- manent health or safety standard, the Secretary [of Labor] is required tomake a threshold find- ing that a place of employment is unsafe—in the sense that significant risks are present and can be eliminated or lessened by a change in practices” (Industrial Union Department, AFL- CIO v. American Petroleum Institute U.S. at 642). The Court broadly describes the range of risks OSHA might determine to be significant: It is the agency’s responsibility to determine in the first instance what it considers to be a “signifi- cant” risk. Some risks are plainly acceptable and others are plainly unacceptable (emphasis added). For example, if the odds are 1 in 1 billion

that a person will die from cancer by taking a drink of chlorinated water, the risk clearly could not be considered significant. On the other hand, if the odds are 1 in 1,000 that reg- ular inhalation of gasoline vapors that are 2% benzene will be fatal, a reasonable person might consider the risk significant and take appropriate steps to decrease or eliminate it. The Court further stated:

The requirement that a “significant” risk be identified is not a mathematical straitjack- et. Although the agency has no duty to cal- culate the exact probability of harm, it does have an obligation to find that a significant risk is present before it can characterize a place of employment as “unsafe” and pro- ceed to promulgate a regulation.

Abstract: The term acceptable risk is becoming the norm. The more frequent use over time of the term acceptable risk in standards and guidelines is notable. SH&E personnel reluctant to adopt the concept implied by the term would do well to focus on the breadth and implication of this evolution, and recon- sider their views.

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Acceptable risk:An acceptable level of risk for regulations and special permits is established by consideration of risk, cost/benefit and pub- lic comments. Relative or comparative risk analysis is most often used where quantitative risk analysis is not practical or justified. Public participation is important in a risk analysis process, not only for enhancing the public’s understanding of the risks associated with hazardous materials transportation, but also for ensuring that the point of view of all major segments of the population-at-risk is included in the analyses process. Risk and cost/benefit analysis are important

tools in informing the public about the actual risk and cost as opposed to the perceived risk and cost involved in an activity. Through such a public process PHMSA establishes hazard clas- sification, hazard communication, packaging and operational control standards.

12) ANSI/PMMI B155.1-2006 on packaging machinery and packaging-related converting machinery contains this definition: “Acceptable risk: risk that is accepted for a given task or hazard. For the purpose of this standard the terms acceptable risk and tolerable risk are considered synonymous (3.1).” 13) In the 2007 revision of BS OHSAS 18001:2007

on occupational health and safety management sys- tems, British Standards Institution (BSI) made a sig- nificant change. Specifically, the term tolerable risk was replaced with the term acceptable risk (3.1). 14) In the introduction of IEC 60601-1-9 (2007),

which addresses medical equipment design, IEC states, “The standard includes the evaluation of whether risks are acceptable (risk evaluation).” 15) A machinery safety document issued in 2009

by the Institute for Research for Safety and Security atWork and the Commission for Safety and Security at Work in Quebec, Canada, states, “When machine- related hazards . . . cannot be eliminated through inherently safe design, they must then be reduced to an acceptable level.” 16) ASSE’s (2009) technical report on prevention

through design includes the following information:

Scope and Purpose 1.3 The goals of applying prevention through design concepts are to:

1.3.1 Achieve that state for which risks are at an acceptable level.

Definitions Acceptable risk: That risk for which the probabil- ity of a hazard-related incident or exposure occur- ring and the severity of harm or damage that may result are as low as reasonably practicable (ALARP) and tolerable in the setting being con- sidered. ALARP: that level of risk which can be further lowered only by an increment in resource expen- diture that is disproportionate in relation to the resulting decrement of risk.

Worksite Analysis.Ahazard identification and analysis system must be implemented to sys- tematically identify basic and unforeseen safety and health hazards, evaluate their risks, and pri- oritize and recommendmethods to eliminate or control hazards to an acceptable level of risk.

6) ANSI/ASSE Z244.1-2003(R2009) on lockout/ tagout states, “A.2: Acceptable level of risk: If the evaluation in A.1.6 determines the risk to be accept- able, then the process is completed. . . .” 7) UN (2009) offers this definition when address-

ing basic terms of disaster risk reduction: “Accept- able risk: The level of potential losses that a society or community considers acceptable given existing social, economic, political, cultural, technical and environmental conditions.” 8) The online Sci-Tech Dictionary (accessed at

www.answers.com/topic/acceptable-risk-geo physics) provides this definition of acceptable risk as the term is used in geology:

Acceptable risk: (geophysics) In seismology, that level of earthquake effects which is judged to be of sufficiently low social and eco- nomic consequence, and which is useful for determining design requirements in structures or for taking certain actions.

9) Australia/New Zealand AS/NZS 4360: 2004 risk management standard uses this definition (in 1.3.16): “Risk acceptance: An informed decision to accept the consequences and the likelihood of a par- ticular risk.” 10) ANSI/AIHAZ10-2005 contains the following

citations with respect to acceptable risk.

E5.1.1: Often, a combination of controls is most effective. In cases where the higher order of controls (elimination, substitution and implementation of engineering controls) does not reduce the risk to an acceptable level, lower order controls may be necessary. Appendix E (Informative), Assessment and

Prioritization (Z10 Section 4.2): The last sen- tence in Step 7 in a Hazard Analysis and Risk Assessment Guide says: “The organization must then determine if the level of risk is acceptable or unacceptable.” A definition of residual risk follows the hazard

analysis and risk assessment guide in Z10: Risk can never be eliminated entirely, though it can be substantially reduced through appli- cation of the hierarchy of controls. Residual risk is defined as the remaining risk after con- trols have been implemented. It is the organi- zation’s responsibility to determine whether the residual risk is acceptable for each task and associated hazard. Where the residual risk is not acceptable, further actions must be taken to reduce risk. 11) DOT’s Pipeline and Hazardous Materials

Safety Administration (PHMSA, 2005) has issued risk management definitions, including this one:

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risk. One resource, the Framework for Environmental Health Risk Management (The Presidential Congres- sional Commission on Risk Assessment and Risk Management, 1997), was selected for citation because of its broad implications. Excerpts follow.

What Is “Risk” Risk is defined as the probability that a sub- stance or situation will produce harm under specified conditions. Risk is a combination of two factors: •the probability that an adverse event will

occur; •the consequences of the adverse event. Risk encompasses impacts on public health

and on the environment, and arises from expo- sure and hazard. Risk does not exist if exposure to a harmful substance or situation does not or will not occur. Hazard is determined by whether a particular substance or situation has the potential to cause harmful effects. Risk . . . is the probability of a specific outcome, generally adverse, given a particular set of conditions. Residual risk . . . is the health risk remain-

ing after risk reduction actions are implement- ed, such as risks associated with sources of air pollution that remain after implementation of maximum achievable control technology. Risk assessment . . . is an organized process

used to describe and estimate the likelihood of adverse health outcomes from environmental exposures to chemicals. The four steps are haz- ard identification, dose-response assessment, exposure assessment and risk characterization.

Zero Risk: Not Attainable It has long been recognized that zero risk levels

are not attainable. If a facility exists or an activity proceeds, it is impossible to realistically conceive of a situation that presents no probability of an adverse incident or exposure occurring. According to Lowrance (1976): Nothing can be absolutely free of risk. One

About the Foregoing Citations 1) Since it is almost always the case that

resources are limited, this phrase in the WHO citation, “the opportunity costs would be better spent on other, more pressing problems,” has a significant bear- ing on risk acceptance decision making and on priority setting. 2) Several citations relate to the fact that

residual risk cannot be eliminated entirely and that residual risk acceptance decisions are commonly and frequently made. Whenever a productionmachine is turned on, a residual risk level is being accepted. Every time a design decision is made or a product design is approved, thosemaking the decision approve a residual and acceptable risk level. 3) Definitions of acceptable risk nearly

identical to that in ANSI/PMMI B155.1- 2006 appear in ANSI B11-2008, General Safety Requirements Common to ANSI B11 Machines, and ANSI/AMTB11.TR7-2007,ANSI Technical Report for Machines: A Guide on Integrating Safety and Lean Manufacturing Principles in the Use of Machinery. 4) Replacing the term tolerable risk with acceptable

risk in BS OHSAS 18001 by an organization as influ- ential as BSI is noteworthy. In some parts of the world, because of requirements in contract bid situ- ations, companies must show that their safety man- agement systems are “certified.” BS OHSAS 18001 is often the basis of such certification. This modifica- tion by BSI indicates that the goal to be achieved is acceptable risk levels. As the cited references illustrate, the concept of

acceptable risk has been broadly adopted interna- tionally, and the term is becoming the norm. SH&E professionals who are reluctant to adopt this concept would do well to recognize that they have an obli- gation to be current with respect to the state of the art and reconsider their views.

The Nature & Source of Risk Risk is expressed as an estimate of the probabili-

ty of a hazard-related incident or exposure occurring and the severity of harm or damage that could result. All risks with which SH&E professionals deal derive from hazards without exception. A hazard is defined as the potential for harm. Hazards include all aspects of technology and activity that produce risk. Hazards include the characteristics of things (e.g., equipment, dusts, chemicals) and the actions or inactions of people. The probability aspect of risk is defined as the

likelihood of an incident or exposure occurring that could result in harm or damage—for a selected unit of time, events, population, items or activity being considered. The severity aspect of risk is defined as the degree of harm or damage that could reasonably result from a hazard-related incident or exposure. Comparable statements and definitions appear in

much of the current literature on risk and acceptable

Table 1Table 1 Occupations With High Fatality Rates

Note. Data from National Census of Fatal Occupational Injuries in 2007 (USDL 08-1182), by Bureau of Labor Statistics, U.S. Department of Labor, 2008, Washington, DC: Author.

aper 100,000 workers

Although the fatality rates among all employment cate- gories are highest for the occupations high- lighted in Table 1, the public has not demanded that the operations in which they occur cease. The inherent risks in the high-hazard cate- gories are considered tolerable.

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procedures, and plant and hardware come together at the worksite to perform a given task.” Start from the beginning in a process of creating a

new facility and the credibility of Stephan’s state- ment is validated. Consider, first, a site survey for ecological considerations, soil testing, then move into the facility’s construction and fitting. Thousands of safety-related decisions are made

in the processes that result in an imposed level of risk. Usually, those decisions meet (or exceed) appli- cable safety-related codes and standards with respect to issues such as the contour of exterior grounds, sidewalks and parking lots; building foun- dations; facility layout and configuration; floor materials; roof supports; process selection and design; determination of the work methods; aisle spacing; traffic flow; hardware; equipment; tooling; materials to be used; energy choices and controls; lighting, heating and ventilation; fire protection; and environmental concerns. Designers and engineers make decisions on these

issues during the original design processes. Those decisions establish what the designers implicitly believe to be acceptable risk levels. Thus, the occu- pational and environmental risk levels have been largely imposed before a facility begins operation. Indeed, if those employed in such settings conclude that the imposed risks are not acceptable, communi- cation systems should be in place to allow them to express their views and to have them resolved.

Minimum Risk as a Substitute for Acceptable Risk Those who oppose use of the term acceptable

risk often offer substitute terms. One frequent sug- gestion is to say that designers and operators should achieve minimum risk levels or minimize the risks. That sounds good, until one explores application of the terms. Minimum means the least amount or the lowest

amount. Minimization means to reduce something to the lowest possible amount or degree. Assume that the threshold limit value (TLV) for a chemical is 4 ppm. For $10 million, a system can be designed, built and installed that will operate at 2 ppm. For an additional $100 million, a 1 ppm exposure level can be achieved. Increase the investment to $200 million and the result is an exposure level of 0.1 ppm. At 2 ppm, the exposure level is acceptable, but

not minimum because a lower exposure level can be achieved. Requiring that systems be designed and operated to minimum risk levels, that risks be mini- mized, is impractical because the investments neces- sary to do so may be so high that the cost of the product required to recoup the investment and make a reasonable profit would not be competitive in the marketplace.

Designing to Standards as a Substitute for Acceptable Risk Developing consensus standards often involves

lively discussion, strong stances, much debate and many compromises. Some of these standards estab-

can’t think of anything that isn’t, under some circumstances, able to cause harm. Because nothing can be absolutely free of risk, nothing can be said to be absolutely safe. There are degrees of risk and, consequently, there are degrees of safety.

Similar comments appear in ISO/IEC Guide 51, under “The Concept of Safety” (section 5):

There can be no absolute safety: some risk will remain, defined in this guide as residual risk. Therefore a product, process or service can only be relatively safe. Safety is achieved by reducing risk to a tolerable level, defined in this guide as tolerable risk.

In the real world, attaining a zero risk level, whether in the design or redesign processes or in facility operations, is not possible. That said, after risk avoidance, elimination or control measures are taken, the residual risk should be acceptable, as judged by the decision makers. Also, one must recognize that inherent risks

which are acceptable and tolerable in some occupa- tions are not tolerable in others. For example, some work conditions considered tolerable in deep sea fishing (e.g., a pitching and rolling work floor, the ship’s deck) would not be tolerable in other work settings. In other situations, such as for certain chem- ical or radiation exposures designed to function at higher than commonly accepted permissible expo- sure levels, the residual risk will be judged as unac- ceptable and operations at those levels would not be permitted. Nevertheless, society accepts continuation of cer-

tain operations with high occupational and environ- mental risks. This is demonstrated by fatality rate data from the Bureau of Labor Statistics (Table 1, p. 33). The fatality rate (rounded) is the rate per 100,000 workers. The national average fatality rate for all pri- vate industries is 4.0. Although the fatality rates among all employ-

ment categories are highest for the occupations high- lighted in Table 1, the public has not demanded that the operations in which they occur cease. The inher- ent risks in the high-hazard categories are consid- ered tolerable. It should be recognized that considerable research has been undertaken to make those occupations safer.

Opposition to Imposed Risks Literature is abundant about people’s resistance to

being exposed to risks they believe are imposed on them. For some, the aversion to adopting the accept- able risk concept derives from their view that imposed risks are objectionable and are to be rebelled against. Conversely, they accept the significant risks of activities in which they choose to engage (e.g., ski- ing, bicycle riding, driving an automobile). This idea needs exploration, which commences

here with a statement that can withstand a test of good logic. As Stephans (2004) says, “The safety of an operation is determined long before the people,

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assessment and applied risk reduction literature. ALARA stands for as low as reasonably achievable; ALARP stands for as low as reasonably practicable. Use of theALARAconcept as a guideline originated in the atomic energy field. According to Nuclear Regulatory Commission (2007): ALARA . . . means making every reasonable effort to maintain exposures to ionizing radia- tion as far below the dose limits as practical, consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation

lish only minimum requirements. For example, the scope of ANSI/AIHA Z10-2005 states, “This stan- dard defines minimum requirements for occupation- al health and safety management systems.” Also, if a standard is obsolete, using it as a design base may result in designing to obsolescence and perhaps unacceptable risk levels. Semiconductor Equipment and Materials Inter-

national (2006) convincingly addresses the need to, sometimes, go beyond issued safety standards in the design process and to have decisions on acceptable risk levels be based on risk assessments. Compliance with design-based safety stan- dards does not necessarily ensure adequate safety in complex or state-of-the-art systems. It often is necessary to perform hazard analyses to identify hazards that are specific with the system, and develop hazard control measures that ade- quately control the associated risk beyond those that are covered in exist- ing design-based standards. Designing to a particular standardmay

achieve an acceptable risk level, or it may not. In any case, the results of risk assess- ments and subsequent amelioration actions, if necessary, should be dominant in deciding whether acceptable risk levels have been reached.

Considerations in Defining Acceptable Risk If the residual risk for a task or opera-

tion cannot be zero, for what risk level does one strive? Resources are always lim- ited, and there is never enough money to address every hazard identified. As a result, SH&E professionals must give counsel so that the greatest good to socie- ty, employees, employers and product users is attained through applying avail- able resources to obtain acceptable risk levels, practicably and economically. Determining whether a risk is accept-

able requires one to consider many vari- ables. ISO/IEC Guide 51 (1999) speaks to the concept of designing and operating for risk levels as low as reasonably practicable. Tolerable risk [acceptable risk] is deter- mined by the search for an optimal bal- ance between the ideal of absolute safety and the demands to be met by a product, process or service, and factors such as benefit to the user, suitability for purpose, cost effectiveness and con- ventions of the society concerned. Understanding cost effectiveness has

become a more important element in risk acceptance decision making. That brings the discussion to ALARA and ALARP, commonly used acronyms in the risk

Table 2Table 2 Risk Assessment Matrix

Incident or exposure probability descriptions Very low: Improbable, very unlikely Low: Remote, may occur, but not likely Moderate: Occasional, likely to occur sometime High: Probable, likely to occur several times Very high: Frequent, likely to occur repeatedly

Incident or exposure severity descriptions Very low: Inconsequential with respect to: injuries or illnesses, system loss or

down time, or environmental chemical release Low: Negligible: first aid or minor medical treatment only, non-serious

equipment or facility damage, chemical release requiring routine cleanup without reporting

Moderate: Marginal: medical treatment or restricted work, minor subsystem loss or damage, chemical release triggering external reporting requirements

High: Critical: disabling injury or illness, major property damage and busi- ness down time, chemical release with temporary environmental or public health impact

Very high: Catastrophic: one or more fatalities, total system loss, chemical release with lasting environmental or public health impact

Risk scoring and categories Combining probability values with severity descriptions yields a risk score.

That score can be categorized as follows.

Risk score Under 4 Category 1: Remedial action discretionary 4 to 8 Category 2: Remedial action to be taken at appropriate time 9 to 14 Category 3: Remedial action to be given high priority 15 or greater Category 4: Operation not permissible. Immediate action necessary

A risk assessment matrix that assigns numbers to risk levels demonstrates the application of the ALARP principle. Combining the severi- ty and occurrence probability values yields a risk score in the matrix.

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3) For items 1 and 2, deci- sion makers are to consider purpose of the undertaking; state of the technology; costs of improvements in relation to benefits to be obtained; and whether the expenditures for risk reduction in a given situa- tion could be applied else- where with greater benefit. Since resources are always

limited, spending an inordi- nate amount of money to reduce the risk only slightly through costly engineering and redesign is inappropriate, par- ticularly if that money could be better spent elsewhere. This premise can be demonstrated through an example that uses a risk assessment matrix as a part of the decision making.

Risk Assessment Matrix A risk assessment matrix

that assigns numbers to risk levels demonstrates the application of the ALARP principle. One must understand that the numbers in the matrix presented (Table 2, p. 35) are qualitative, not quantitative. They are relational and have mean- ing as they interact with each other. Many other risk assessment matrixes could be used as well. An SH&E professional may want to use other probabil- ity and severity descriptions and risk scoring cate- gories. Combining the severity and occurrence probability values yields a risk score in the matrix. Table 2 also includes information on categorizing the risks and action levels based on urgency. The following example illustrates how a team

used the matrix and applied the ALARP concept to make a decision about acceptable risk. 1) A chemical operation was built 15 years ago.

While engineering modifications have been made in the system over the years, management knows that its operations are no longer state of the art. 2) A risk assessment team is convened to consid-

er the chemically related risks in a particular process in the overall system. 3) In the deliberations, the group refers to its

established hierarchy of controls: a) Eliminate or reduce risks in the design and redesign processes.

b) Reduce risks by substituting less hazardous methods or materials.

c) Incorporate safety devices. d) Provide warning systems. e) Apply administrative controls (e.g., work methods, training, work scheduling).

f) Provide PPE. 4) The group first considers the possibility of

redesigning and replacing the process. Substitution of materials or methods is considered, but the group

to utilization of nuclear energy and licensed materials in the public interest (10 CFR 20.1003). The implication that decision makers are to

“[make] every reasonable effort to maintain expo- sures to ionizing radiation as far below the dose lim- its as practical” provides conceptual guidance in striving to achieve acceptable risk levels in all class- es of operations. ALARP seems to be an adaptation fromALARA.

It has become the more frequently used term for operations outside the atomic arena and it appears more often in the literature. ALARP is that level of risk which can be further lowered only by an incre- ment in resource expenditure that is disproportion- ate in relation to the resulting decrement of risk. The concept embodied in these two terms applies

to the design of products, facilities, equipment, work systems and methods, and environment controls. In the real world, benefits represented by the amount of risk reduction to be obtained and the costs to achieve those reductions are important factors. Trade-offs are frequent and necessary. An appropriate goal in the decision-making

process is to have the residual risk be ALARA. Paraphrasing the terms contained in the definition of ALARAhelps explain the process: 1) Reasonable efforts are to be made to identify,

evaluate, and eliminate or control hazards so that the risks deriving from those hazards are acceptable. 2) In the design and redesign processes for phys-

ical systems and for the work methods, risk levels for injuries and illnesses, and property and environ- mental damage, are to be as far below what would be achieved by applying current standards and guidelines as is economically practicable.

Unacceptable region

ALARP region Steps must be taken to reduce risks to as low as reasonably prac!cable.

Having less importance or urgency

•Immediate ac!on required. Opera!on not permissible, except in rare and extra- ordinary circumstances.

Risk category 4

•Remedial ac!on is to be given high priority.

Risk category 3

•Remedial ac!on to be taken at appropriate !me.

Risk category 2

•Remedial ac!on is discre!onary. Procedures are to be in place to ensure that this risk level is maintained.

Risk category

1

Figure 1Figure 1 The ALARP Principle

ALARP promotes a management review, the intent of which is to achieve acceptable risk levels. Several depictions of the

ALARP concept begin with an inverted triangle because it indicates that risk is greater at the top and much less at the bottom.

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that the definition of acceptable risk included in this article represents the development of and practical use of the term over the past several years.

Social Responsibility: An Emerging Opportunity Formal consideration of social responsibility by

senior executives is a fairly recent development. What is social responsibility?An Internet search will reveal a large number of definitions. This article focuses on two. 1) The World Business Council for Sustainable

Development (2000) defines corporate social respon- sibility as “the continuing commitment by business to behave ethically and contribute to economic development while improving the quality of life of the workforce and their families as well as of the local community and society at large.” 2) Gap Inc. states, “[S]ocial responsibility is fun-

damental to show how we do business. It means everything from ensuring that workers are treated fairly to addressing our environmental impact.” It is logical to suggest that if a company initiates a

social responsibility endeavor which is to include the well-being of workers, the environment and the com- munity at large, knowledge and application of accept- able risk principles would inform its decisionmaking. The result would be efficient allocation of resources, fewer injuries and illnesses and property damage inci- dents, and serving the community well. That seems to present opportunities for SH&E professionals.

The State of the Art in Risk Assessment SH&E professionals must understand that risk

assessment is as much an art as science and that sub- jective judgments—educated, to be sure—are made on incident or exposure probability and the severity of outcome to arrive at a risk category. Also, one must recognize that economically applicable risk assessment methodologies have not been developed to resolve all risk situations. For example, when asked, “How would you

assess the cumulative risk in an operation in which there was an unacceptable noise level and toluene was used in the process?” one would hope that resource material such as EPA’s (2003) Framework for Cumulative Risk Assessment would provide an answer. It does not. The agency is cautionary about cumulative risk assessment methods. It should be acknowledged by all practitioners of cumulative risk assessment that in the cur- rent state of the science therewill be limitations in methods and data available (p. 31). Finding a commonmetric for dissimilar risks

is not an analytical process, because some judg- ments should be made as to how to link two or more separate scales of risks. These judgments often involve subjective values, and because of this, it is a deliberative process (p. 55). Calculating individual stressor risks and

then combining them largely presents the same challenges as combination toxicology but also adds some statistical stumbling blocks (p. 66).

determines that such opportunities have already been addressed. Safety devices and warning sys- tems are considered state of the art, and mainte- nance is considered superior. 5) Occurrence probability for a chemically related

illness is judged to be moderate (3) and the severity level is moderate (3). Thus, the risk score is 9, which is in Category 3 and remedial action is to be given high priority. 6) The team recognizes that to reduce the risk fur-

ther, appropriate training must be delivered and repeated, and standard operating procedures and the use of PPE must be rigidly enforced. 7) Management agrees to fund the necessary ad-

ministrative improvements. 8) Assuming that these improvements are made,

the risk assessment group decides that the probabil- ity of occurrence of an illness from a chemical expo- sure would be low (2) and that the severity of harm expected would be low (2). Thus, the risk score is 4, in Category 1. 9) Reengineering and replacing the process would

reduce the probability level to very low (1) and the severity level to very low (1), thereby achieving a risk score of 1, also is in Category 1. The estimated cost of redesigning and replacing the process, $1.5 million, was considered disproportionate with respect to the amount of risk reduction to be obtained. 10) The risk assessment group tells management

that it would prefer having the money spent on a wellness center.

The ALARP Principle ALARPpromotes amanagement review, the intent

of which is to achieve acceptable risk levels. Practical, economic risk trade-offs are frequent and necessary in the benefit/cost deliberations that occur when deter- mining whether the costs to reduce risks further can be justified “by the resulting decrement in risk.” Several depictions of the ALARP concept begin

with an inverted triangle (Figure 1) because it indi- cates that risk is greater at the top and much less at the bottom. Figure 1 shows the concept combined with elements in the risk assessment matrix.

Defining Acceptable Risk This author’s definition of acceptable risk is

included in ASSE TR-Z790.001-2009. Risk acceptance is a function of many factors and varies considerably across industries (e.g., mining vs. medical devices vs. farming). Even at locations of a single global compa- ny, acceptable risk levels can vary. Company culture and the culture of the country in which a facility is located influence risk acceptability, according to col- leagues working in global companies. Training, expe- rience and resources also can influence acceptable risk levels. Risk acceptability is also time dependent, in that what is acceptable today may not be accept- able tomorrow, next year or the next decade. A sound, workable definition of acceptable risk

must encompass hazards, risks, probability, severity and economic considerations. This author believes

ALARP is that level of risk which can be further lowered only by an incre- ment in resource expenditure that is dispro- portionate in relation to the resulting decrement of risk.

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38 PROFESSIONAL SAFETY MAY 2010 www.asse.org

British Standards Institution (BSI). (2007). Occupational health and safety management systems: Requirements (BS OHSAS 18001:2007). London: Author.

Bureau of Labor Statistics. (2008, Aug. 20). National census of fatal occupational injuries in 2007 (USDL 08-1182). Washington, DC: U.S. Department of Labor, Author.

DOT. (2005). Risk management definitions. Washington, DC: Author, Pipeline and Hazardous Materials Safety Administration. Retrieved March 19, 2010, from http://www.phmsa.dot.gov/haz mat/risk/definitions.

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Fewtrell, L. & Bartram, J. (Eds.). (2001).Water quality: Guide- lines, standards and health. London: IWAPublishing for World Health Organization.

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Health and Safety Executive.ALARP “at a glance.” London: Author. Retrieved March 19, 2010, from http://www.hse.gov.uk/ risk/theory/alarpglance.htm. Industrial Union Department, AFL-CIO v. American

Petroleum Institute U.S. at 642. Institute for Research for Safety and Security at Work & The

Commission for Safety and Security at Work in Quebec. (2009). Machine safety: Prevention of mechanical hazards. Quebec, Canada: Author. Retrieved March 19, 2010, from http://www .irsst.qc.ca/files/documents/PubIRSST/RG-597-Pref-TCont -Intr.pdf.

International Electrotechnical Commission (IEC). (2007). International standard for environmentally conscious design of medical equipment (IEC 60601-1-9). Geneva: Author.

International Organization for Standardization (ISO)/IEC. (1999). Safety aspects: Guidelines for their inclusion in standards [ISO/IEC Guide 51:1999(E)]. Geneva: Author.

Lowrance, W.F. (1976). Of acceptable risk: Science and the deter- mination of safety. Los Altos, CA: William Kaufman Inc.

Manuele, F.A. (2008). Advanced safety management: Focusing on Z10 and serious injury prevention. Hoboken, NJ: John Wiley & Sons.

Manuele, F.A. (2003). On the practice of safety (3rd ed.). Hobo- ken, NJ: John Wiley & Sons.

Manuele, F.A. & Main, B. (2002, Jan.). On acceptable risk. Occupational Hazards. Retrieved March 19, 2010, from http://ehs today.com/news/ehs_imp_35066.

Nuclear Regulatory Commission. (2007). 20.1003 Definitions: ALARA. Washington, DC: Author. Retrieved March 19, 2010, from http://www.nrc.gov/reading-rm/doc-collections/cfr/part 020/part020-1003.html.

OSHA. (2003). Voluntary Protection Programs: Policies and procedures manual (archived). Washington, DC: U.S. Department of Labor, Author. Retrieved March 19, 2010, from http://www .osha.gov/pls/oshaweb/owadisp.show_document?p_table =DIRECTIVES&p_id=2976.

Presidential/Congressional Commission on Risk Assess- ment and Risk Management. (1997). Framework for environmental health risk management.Washington, DC: Author.

Semiconductor Equipment and Materials International (SEMI). (2006). Environmental, health and safety guideline for semiconductor manufacturing equipment (SEMI S2-0706). San Jose, CA: Author.

SEMI. (1996). Safety guideline for risk assessment (SEMI S10- 1996). Mountain View, CA: Author.

Standards Association of Australia. (2004). Risk management standard (AS/NZS 4360: 2004). Strathfield, NSW, Australia: Author.

Stephans, R.A. (2004). System safety for the 21st century. Hobo- ken, NJ: John Wiley & Sons.

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Where multiple, diverse hazards exist, the practi- cal approach is to treat each hazard independently, with the intent of achieving acceptable risk levels for all. In the noise and toluene example, the hazards are indeed independent. Complex situations, or when evaluating competing solutions to complex systems, may require the assistance of specialists with knowl- edge of more sophisticated risk assessment method- ologies such as hazard and operability analysis or fault tree analysis. For most applications, however, the author does not recommend that diverse risks be summed through what could be a questionable methodology.

Conclusion Risk acceptance is the deliberate decision to

assume a risk that is low enough with respect to the probability of a hazard-related incident or exposure occurring and the severity of harm or damage that may result, and which is considered tolerable in a given situation. Management’s decision to accept a risk should be deliberate and the criteria for the deci- sion should be documented. In an ideal world, all personnel who are impacted should be involved in or be informed of risk acceptance decisions. Use of the term acceptable risk has arrived. It is

becoming a norm. In organizations with advanced safety management systems, the idea of achieving practicable and acceptable risk levels throughout all operations is a cultural value. It is suggested that SH&E professionals adopt the concept of attaining acceptable risk levels as a goal to be embedded in every risk elimination or reduction action proposed. To achieve that goal, SH&E professionals must edu- cate others on the benefits of applying the concept. SH&E professionals also must be able to work

through the greatly differing views people can have about risk levels, incident and exposure probabili- ties, and severity. Workers may have differing views about risk and they should be considered for their value. With respect to environmental risks, commu- nity views must be considered as well. In arriving at acceptable risk levels where the

hazard/risk scenarios are complex, it is best to gath- er a team of experienced personnel for their contri- butions and for their buy-in to the conclusions. �

References ANSI/AIHA. (2005). American national standard for occupa-

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Management’s decision to accept a risk should be

deliberate and the criteria for the decision should be

documented.

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http://www.asse.org
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