Executive Office of the President Executive Office of the President 

Office of Management and Budget Office of Science and Technology Policy 

September 19, 2007 

M-07-24 

MEMORANDUM FOR THE HEADS OF EXECUTIVE DEPARTMENTS AND AGENCIES 

FROM: Susan E. Dudley 

 Administrator, Office of Information and Regulatory Affairs, 

 Office of Management and Budget 

 Sharon L. Hays 

 Associate Director and Deputy Director for Science, 

 Office of Science and Technology Policy 

SUBJECT: Updated Principles for Risk Analysis

 Federal agencies take a variety of actions to improve public health, safety, and the 

environment. Agency activities designed to reduce risks are influenced by numerous factors, 

including Congressional priorities, information on the degree of risk faced by different 

populations, entities, or individuals, resources available, and the ease of implementing chosen 

priorities. Development of these actions often begins with an assessment of the risks posed 

under certain conditions, as well as assessments of the potential changes in risk achievable due to 

different policy options. 

In 1995, an interagency working group, co-chaired by the Office of Management and Budget 

(OMB) and the Office of Science and Technology Policy (OSTP), developed a set of principles 

to guide policymakers in assessing, managing, and communicating policies to address 

environmental, health, and safety risks (the 1995 Principles).1

 The 1995 Principles, shared with 

regulatory agencies in a memorandum from Sally Katzen, then Administrator of OMB’s Office 

of Information and Regulatory Affairs (OIRA), remain valid today. 

This Memorandum reinforces the 1995 Principles with reference to more recent guidance 

from the scientific community, the Congress, and the Executive Branch. This Memorandum also 

benefits from feedback received on OMB’s Proposed Risk Assessment Bulletin issued in 2006 

(Proposed Risk Assessment Bulletin).2

 

 

1

 U.S. Office of Mgmt. and Budget (OMB), Memorandum for the Regulatory Working Group, Principles for Risk 

Analysis (1995), available at http://www.whitehouse.gov/omb/inforeg/regpol/jan1995_risk_analysis_principles.pdf. 2

 OMB, Proposed Risk Assessment Bulletin, (2006) [hereinafter Proposed Risk Assessment Bulletin], available at 

http://www.whitehouse.gov/omb/inforeg/proposed_risk_assessment_bulletin_010906.pdf. 
 2

 In January 2006, OIRA, in consultation with OSTP, released the Proposed Risk Assessment 

Bulletin for public comment and asked the National Academy of Sciences (NAS) to conduct an 

expert peer review. 3

 The NAS issued its report on the Proposed Risk Assessment Bulletin in 

2007 (the 2007 NAS Report on the Proposed Risk Assessment Bulletin). 4

 While supportive of 

the goal of “increasing the quality and objectivity of risk assessment in the federal government,” 

the NAS recommended an approach that would “outline goals and general principles of risk 

assessment.”5 After carefully evaluating these constructive recommendations from the NAS, as 

well as feedback from a rigorous interagency review, and public comments,6 we have decided 

not to issue the bulletin in final form. Rather, we are issuing this Memorandum to reinforce 

generally-accepted principles for risk analysis upon which a wide consensus now exists. 

Recognizing the diversity of documents that stem from risk analysis techniques, this 

Memorandum reinforces generally-accepted principles for risk analysis related to environmental, 

health, and safety risks.7 As a whole, the Memorandum endeavors to enhance the scientific 

quality, objectivity, and utility of Agency risk analyses and the complementary objectives of 

improving efficiency and consistency among the Federal family.8

 The general principles 

presented here should continue to assist and guide agencies as they conduct risk analyses, and 

thereby should enhance the multiple decisions that are based upon these analyses. 

The 1995 Principles were divided into five parts: general principles, principles for risk 

assessment, principles for risk management, principles for risk communication, and priority 

setting.9 This Memorandum reiterates each of these principles (in bold text) and, where 

appropriate, highlights and references more recent guidance (in plain text). OMB and OSTP will 

 

3

 See Press Release, OMB, OMB Requests Peer Review of Proposed Risk Assessment Bulletin (Jan. 9, 2006), 

available at http://www.whitehouse.gov/omb/pubpress/2006/2006-01.pdf. 4

 National Research Council, National Academy of Sciences, Scientific Review of the Proposed Risk Assessment 

Bulletin from the Office of Management and Budget (2007) [hereinafter 2007 NAS Report on the Proposed Risk 

Assessment Bulletin]. 

5 Id. at 6 - 7. 6

 OMB received 79 public comments on the Proposed Risk Assessment Bulletin. These comments are posted on 

OMB’s website, available at http://www.whitehouse.gov/omb/inforeg/comments_rab/list_rab2006.html. 7

 While many of the principles presented in this Memorandum may be relevant to other fields, such as financial or 

information technology risk analyses, the focus of this Memorandum is on those risk analyses related to 

environmental, health, and safety risks. 

8

 The enhancement of information quality, objectivity, transparency, and reproducibility is addressed in other OMB 

guidance as well. See OMB, Circular A-4 for Regulatory Review (2003) [hereinafter Circular A-4] (includes 

requirements for regulatory analysis as it relates to risk management decisions, particularly those required under 

Executive Order 12866), available at http://www.whitehouse.gov/omb/circulars/a004/a-4.pdf. In addition, pursuant 

to what is commonly referred to as the Information Quality Act (Sec. 515 of the Treasury and General Government 

Appropriations Act for FY 2001, Pub. L. No. 106-554), OMB issued government-wide Guidelines for Ensuring and 

Maximizing the Quality, Objectivity, Utility, and Integrity of Information Disseminated by Federal Agencies (2002), 

67 Fed. Reg. 8452 (Feb. 22, 2002) [hereinafter Information Quality Guidelines], available at

http://www.whitehouse.gov/omb/fedreg/reproducible2.pdf; and its Final Information Quality Bulletin for Peer 

Review (2004), 70 Fed. Reg.2664 (Jan. 14, 2005) [hereinafter Peer Review Bulletin], available at

http://www.whitehouse.gov/omb/memoranda/fy2005/m05-03.pdf. These documents were each issued first as a 

proposal for public comment. In addition, the Information Quality Guidelines were then implemented by agencies 

in their own agency-specific information quality guidelines. This Memorandum is intended to complement and 

support the Information Quality Guidelines. 

9

 This framework is consistent with the long-standing distinction between risk assessment, risk management, and 

risk communication. See National Research Council, National Academy of Sciences, Risk Assessment in the 

Federal Government: Managing the Process (1983). 
 3

work with Federal agencies to ensure consistency with the principles in this memorandum. 

Agencies should review their current risk analysis practices and guidelines and incorporate these 

principles as they develop, update, and issue risk analyses and guidelines. 

 Should you have any questions regarding this Memorandum, or would like to discuss it, 

please do not hesitate to contact either of us or our staff at 202-395-4852 (OIRA) or 202-456-

7116 (OSTP). 

General Principles

1. These Principles are intended to be goals for agency activities with respect to the 

assessment, management, and communication of environmental, health, and safety 

risks. Agencies should recognize that risk analysis is a tool—one of many, but 

nonetheless an important tool—in the regulatory tool kit. These Principles are intended 

to provide a general policy framework for evaluating and reducing risk, while 

recognizing that risk analysis is an evolving process and agencies must retain sufficient 

flexibility to incorporate scientific advances. 

The 2007 NAS Report on the Proposed Risk Assessment Bulletin recommended that OMB 

“develop goals for risk assessment that emphasize the central objective of enhanced scientific 

quality and the complementary objectives of efficiency and consistency among agencies 

evaluating the same or similar risks.” 10 Recognizing that “[r]isk assessment is not a monolithic 

process or a single method,” and that “[a]ll risk assessments share some common principles, but 

their application varies widely among domains,” the NAS recommended that “affected federal 

agencies develop their own technical risk assessment guidelines that are consistent with the 

OMB general principles.”11

2. The Principles in this document are intended to be applied and interpreted in the 

context of statutory policies and requirements, and Administration priorities. 

3. As stated in Executive Order No. 12866, “ In setting regulatory priorities, each agency 

shall consider, to the extent reasonable, the degree and nature of the risks posed by 

various substances or activities within its jurisdiction” [Section 1(b)(4)]. Further, in 

developing regulations, federal agencies should consider “...how the action will reduce 

risks to public health, safety, or the environment, as well as how the magnitude of the 

risk addressed by the action relates to other risks within the jurisdiction of the agency” 

[Section 4(c)(1)(D)].12 

Agencies should refer to Circular A-4 for expanded and updated guidance regarding best 

practices for agency regulatory analysis. 13

 

10 2007 NAS Report on the Proposed Risk Assessment Bulletin, supra note 4, at 110. 11 Id. at 106, 110-11. 12 See Exec. Order No. 12866, 58 Fed. Reg. 51,735 (Oct. 4, 1993), available at

http://www.whitehouse.gov/omb/inforeg/eo12866.pdf. See also Exec. Order No. 13132, 72 Fed. Reg. 2763 (Jan. 23, 

2007), available at http://www.whitehouse.gov/omb/inforeg/eo12866/index_eo12866.html. 13 See footnote 8. Circular A-4 refined OMB’s “Economic Analysis of Federal Regulations Under Executive Order 

12866” (1996) (a “best practices” guide to preparing a regulatory analysis), available at
 4

4. In undertaking risk analyses, agencies should establish and maintain a clear distinction 

between the identification, quantification, and characterization of risks, and the 

selection of methods or mechanisms for managing risks. Such a distinction, however, 

does not mean separation. Risk management policies may induce changes in human 

behaviors that can alter risks (i.e., reduce, increase, or change their character), and 

these linkages must be incorporated into evaluations of the effectiveness of such 

policies. 

5. The depth or extent of the analysis of the risks, benefits and costs associated with a 

decision should be commensurate with the nature and significance of the decision. 

Subsequent reports have re-affirmed this principal. The 1997 Presidential/Congressional 

Commission on Risk Assessment and Risk Management (referred to as the Presidential 

Commission on Risk) issued a two-volume report that stated as follows: 

The level of detail considered in a risk assessment and included in a risk characterization 

should be commensurate with the problem’s importance, expected health or environmental 

impact, expected economic or social impact, urgency, and level of controversy, as well as 

with the expected impact and cost of protective measures.

14

A 2007 NAS report on global change assessments evaluated lessons learned from relevant past 

global change assessments.15 The NAS, drawing on its analysis and the relevant literature, 

identified essential elements of effective assessments and included elements relating to the 

adequacy of funding and the balance between benefits of the assessment and the opportunity 

costs of producing it.16

 http://www.whitehouse.gov/omb/inforeg/riaguide.html. The “best practices” guide was issued as guidance in 2000, 

OMB’s Memorandum for the Heads of Departments and Agencies on Guidelines to Standardize Measures of Costs 

and Benefits and the Format of Accounting Statements (2000), available at

http://www.whitehouse.gov/omb/memoranda/m00-08.pdf; and reaffirmed in 2001, OMB’s Memorandum for the 

President’s Management Council on Presidential Review of Agency Rulemaking (2001), available at

http://www.whitehouse.gov/omb/inforeg/oira_review-process.html. Before finalization, Circular A-4 went through 

public comment, interagency review, and peer review.

14 Presidential/Congressional Commission on Risk Assessment and Risk Management, Framework for 

Environmental Health Risk Management, 1 Final Report 25 (1997) [hereinafter Risk Commission Report I]. 15 See National Research Council, National Academy of Sciences, Analysis of Global Change Assessments: Lessons 

Learned (2007) [hereinafter 2007 NAS Report on Global Change Assessments]. 16 Id., supra note 15, at 4 (two essential elements of effective assessments are “[a]dequate funding that is both 

commensurate with the mandate and effectively managed to ensure an efficient assessment process” and a “balance 

between the benefits of a particular assessment and the opportunity costs (e.g., commitments of time and effort) to 

the scientific community”). 
 5

Principles for Risk Assessment

1. Agencies should employ the best reasonably obtainable scientific information to 

assess risks to health, safety, and the environment. 

Risk analyses should be based upon the best available scientific methodologies, information, 

data, and weight of the available scientific evidence.17 The Presidential Commission on Risk 

observed: 

Because so many judgments must be based on limited information, it is critical that all 

reliable information be considered. Risk assessors and economists are responsible for 

providing decision-makers with the best technical information available or reasonably 

attainable, including evaluations of the weight of the evidence that supports different 

assumptions and conclusions.18

Congress emphasized using the best available scientific evidence for risk information in the 1996 

amendments to the Safe Drinking Water Act (SDWA).19 Pursuant to the SDWA, an agency is 

directed “to the degree that an agency action is based on science,” to use: 

 (i) the best available, peer-reviewed science and supporting studies conducted in 

accordance with sound and objective scientific practices; and (ii) data collected by 

accepted methods or best available methods (if the reliability of the method and the 

nature of the decision justifies use of the data).20 

Agencies have adopted or adapted this SDWA standard in their Information Quality Guidelines 

with regard to the analysis of risks to human health, safety, and the environment.21 

2. Characterizations of risks and of changes in the nature or magnitude of risks should 

be both qualitative and quantitative, consistent with available data. The 

characterizations should be broad enough to inform the range of policies to reduce 

risks. 

In the 1996 SDWA amendments, Congress adopted a basic quality standard for the 

dissemination of public information about risks of adverse health effects. Under the 1996 

 

17 In this Memorandum, “scientific” information includes information related to applied sciences (such as 

engineering) and technical information related to these fields. 18 Risk Commission Report I, supra note 14, at 38. The Risk Commission Report I provides examples of the kinds 

of considerations entailed in making judgments on the basis of the weight of the scientific evidence in a toxicity 

study: quality of the toxicity study, appropriateness of the toxicity study methods, consistency of results across 

studies, biological plausibility of statistical associations, and similarity of results to responses and effects in humans. 19 42 U.S.C. § 300g-1(b)(3)(A,B). 

20 42 U.S.C. § 300g–1(b)(3)(A). 

21 Links to agency specific information quality guidelines can be found in the OMB Draft 2007 Report to Congress 

on the Costs and Benefits of Federal Regulations, Appendix C, available at 

http://www.whitehouse.gov/omb/inforeg/2007_cb/2007_draft_cb_report.pdf. For specific examples of agency 

guidelines, see http://dms.dot.gov/submit/DataQualityGuidelines.pdf (Department of Transportation guidelines), 

http://aspe.hhs.gov/infoquality/Guidelines/index.shtml (Department of Health and Human Services guidelines), 

http://www.sti.nasa.gov/qualinfo.html (National Aeronautics and Space Administration guidelines), 

http://www.dol.gov/informationquality.htm (Department of Labor guidelines). 
 6

SDWA amendments, the Environmental Protection Agency is directed “to ensure that the 

presentation of information on public health effects is comprehensive, informative, and 

understandable.”22 The Information Quality Guidelines adapt this language and further direct 

the agencies to: 

in a document made available to the public in support of a regulation [to] specify, to the 

extent practicable— (i) each population addressed by any estimate [of applicable risk 

effects]; (ii) the expected risk or central estimate of risk for the specific populations 

[affected]; (iii) each appropriate upper-bound or lower-bound estimate of risk; (iv) each 

significant uncertainty identified in the process of the assessment of [risk] effects and the 

studies that would assist in resolving the uncertainty; and (v) peer-reviewed studies 

known to the [agency] that support, are directly relevant to, or fail to support any estimate 

of [risk] effects and the methodology used to reconcile inconsistencies in the scientific 

data.23 

Agencies have adopted or adapted this standard in their Information Quality Guidelines with 

regard to analysis of risks to human health, safety, and the environment.24 

In addition, the Information Quality Guidelines state that agency disseminations should be 

objective; these guidelines, as well as individual agency information quality guidelines, provide 

further discussion of objectivity and its application in agency disseminations.25 While risks 

should not be minimized nor exaggerated, the 2007 NAS Report on the Proposed Risk 

Assessment Bulletin stated that “[i]nformation on the variability of effects across potentially 

affected populations is essential to decision-making.”26 

When characterizing risk in its 1996 report on understanding risk and how it informs decisions, 

the NAS stated that “quantitative models to organize and interpret data are particularly important 

to risk characterization.”27 When a risk analysis is influential,28 increased efforts to provide 

useful quantitative estimates of risk are particularly important. Due to the inherent uncertainties 

associated with estimates of risk, presentation of a single estimate may be misleading and 

 

22 42 U.S.C. § 300g-1(b)(3)(B). 

23 See Information Quality Guidelines, supra note 8. 24 See footnote 21. 25 See Information Quality Guidelines, supra note 8. On a substantive level, objectivity ensures accurate, reliable 

and unbiased information. 

26 See 2007 NAS Report on the Proposed Risk Assessment Bulletin, supra note 4, at 63 (in referring to the Proposed 

Risk Assessment Bulletin’s statement that risk assessments should be presented such that they are “neither 

minimizing nor exaggerating the nature and magnitude of risks,” the NAS stated that this “could, however, degrade 

risk analysis if it were interpreted so as to deprive decision-makers of important information on sensitive 

subpopulations on the grounds that such information may generate risk estimates considerably higher than a central 

tendency or general population estimates.”). 

27 National Research Council, National Academy of Sciences, Understanding Risk: Informing Decisions in a 

Democratic Society 99-100 (1996) [hereinafter 1996 NAS Report on Understanding Risk and Informing Decisions]. 28 In this Memorandum, the term “influential” is defined in the same way as it is defined in the Information Quality 

Guidelines. Influential means that “the agency can reasonably determine that dissemination of the information will 

have or does have a clear and substantial impact on important public policies or important private sector decisions.” 

In their information quality guidelines, agencies have defined “influential” in ways appropriate for them given the 

nature and multiplicity of issues for which the agencies are responsible. 
 7

provide a false sense of precision.29 Expert panels agree that when a quantitative 

characterization of risk is provided, a range of plausible risk estimates should be provided.30 

When something more than a superficial analysis can be conducted, quantitative uncertainty 

analysis, sensitivity analysis, and a discussion of model uncertainty can greatly inform risk 

management decisions.31

 

Experts have recognized that when presenting risk information qualitatively, or quantitatively, 

agencies’ methodological approaches will likely vary and will depend upon the context for 

which the analysis is used.32 These methodologies are continuing to develop as the science 

associated with quantitative uncertainty analysis advances. As technical guidance continues to 

develop, so too should agencies’ presentation of quantitative risk information. 

 

29 See National Research Council, National Academy of Sciences, Models in Environmental Regulatory Decision 

Making 136 (2007) [hereinafter 2007 NAS Report on Environmental Decision Making] (“there are substantial 

problems in reducing the results of a large-scale study with many sources of uncertainty to a single number or even a 

single probability distribution. We contend that such an approach draws the line between the role of analysts and 

the role of policy makers in decision making at the wrong place.”); Id. at 7 (“Effective decision making will require 

providing policy makers with more than a single probability distribution for a model result (and certainly more than 

just a single number, such as the expected net benefit, with no indication of uncertainty). Such summaries obscure 

the sensitivities of the outcome to individual sources of uncertainty, thus undermining the ability of policy makers to 

make informed decisions and constraining the efforts of stakeholders to understand the basis for the decisions.”). 

See also 1996 NAS Report on Understanding Risk and Informing Decisions, supra note 27, at 66 (“Risk 

characterizations often fail because they attribute meaning to scientific estimates in ways that mislead participants in 

the risk decision process or are incomprehensible to them.”). 30 See 2007 NAS Report on the Proposed Risk Assessment Bulletin, supra note 4, at 37 (“The committee agrees 

with OMB that in some cases ‘presentation of single estimates of risk is misleading’ and that ranges of ‘plausible 

risk’ should be presented; however, the challenge is in the operational definitions of such words as central, expected, 

and plausible.”) (emphasis in original). 31 See 2007 NAS Report on Environmental Decision Making, supra note 29, at 6 (“A wide range of possibilities is 

available for performing model uncertainty analysis. At one extreme, all model uncertainties could be represented 

probabilistically, and the probability distribution of any model outcome of interest could be calculated. However, in 

assessing environmental regulatory issues, these analyses generally would be quite complicated to carry out 

convincingly, especially when some of the uncertainties in critical parameters have broad ranges or when the 

parameter uncertainties are difficult to quantify. Thus, although probabilistic uncertainty analysis is an important 

tool, requiring EPA to do complete probabilistic regulatory analyses on a routine basis would probably result in 

superficial treatments of many sources of uncertainty. The practical problems of performing a complete 

probabilistic analysis stem from models that have large numbers of parameters whose uncertainties must be 

estimated in a cursory fashion. Such problems are compounded when models are linked into a highly complex 

system, for example, when emissions and meteorological model results are used as inputs into an air quality 

model.”); Id. at 7 (“It is not necessary to choose between purely probabilistic approaches and deterministic 

approaches. Hybrid analyses combining aspects of probabilistic and deterministic approaches might provide the 

best solution for quantifying uncertainties, given the finite resources available for any analysis. For example, a 

sensitivity analysis might be used to determine which model parameters are most likely to have the largest impacts 

on the conclusions, and then a probabilistic analysis could be used to quantify bounds on the conclusions due to 

uncertainties in those parameters.”). 

32 Id. at 7-8 (“In some cases, presenting results from a small number of model scenarios will provide an adequate 

uncertainty analysis (for example, cases in which the stakes are low, modeling resources are limited, or insufficient 

information is available). In many instances, however, probabilistic methods will be necessary to characterize 

properly at least some uncertainties and to communicate clearly the overall uncertainties.”). 
 8

3. Judgments used in developing a risk assessment, such as assumptions, defaults, and 

uncertainties, should be stated explicitly. The rationale for these judgments and their 

influence on the risk assessment should be articulated. 

If important judgments are supported by, or conflict with, empirical data, that information should 

be discussed. The discussion should address the range of scientific and/or technical opinions 

regarding the likelihood of plausible alternate judgments and the direction and magnitude of any 

resulting changes that might arise in the analysis due to changes in key judgments.33 Every 

effort should be made to perform a quantitative evaluation of reasonable alternative 

assumptions.34 When an analysis combines multiple assumptions, the basis and rationale for 

combining the assumptions should be explicitly described.35 

Critical judgments are often made when choosing and presenting study results. Results based on 

different effects and/or different studies should be presented to convey how the choice of effect 

and/or study influences the analysis. The presentation of information regarding different 

scientifically plausible endpoints should allow for a robust discussion of the available data, 

associated uncertainties, and underlying science. In its 2007 report evaluating global change 

assessments, the NAS recommended that “[t]here should be a deliberate effort to clarify the 

importance of alternative assumptions and to illustrate the impacts of uncertainties.”36 When 

relying on data from one study over others, the agency should provide a clear rationale and/or 

scientific basis for its choice.37 

4. Risk assessments should encompass all appropriate hazards (e.g., acute and chronic 

risks, including cancer and non-cancer risks, to human health and the environment). 

In addition to considering the full population at risk, attention should be directed to 

subpopulations that may be particularly susceptible to such risks and/or may be 

more highly exposed. 

A good risk analysis should clearly summarize the scope of the assessment, including a 

description of: the agent, technology and/or activity that is the subject of the analysis; the hazard 

of concern; the affected entities (populations, subpopulations, individuals, natural resources, 

ecosystems, critical infrastructure, or other) that are the subject of the assessment; the 

exposure/event scenarios relevant to the objectives of the assessment; and the type of event-

 

33 See 1996 NAS Report on Understanding Risk and Informing Decisions, supra note 27, at 53 (“Simplifying 

assumptions generate especially serious problems when some of the assumptions are unreasonable in the face of 

information available to people outside the analytical process.”). 

34 Id. at 99 (“Without good analysis, deliberative processes can arrive at agreements that are unwise or not 

feasible.”). See also National Research Council, National Academy of Sciences, Health Risks from Dioxin and 

Related Compounds 7 (2006) (“Although EPA [in its dioxin assessment] addressed many sources of variability and 

uncertainty qualitatively, the committee noted that the Reassessment would be substantially improved if its risk 

characterization included more quantitative approaches. Failure to characterize variability and uncertainty 

thoroughly can convey a false sense of precision in the conclusions of the risk assessment.”). 

35 See Circular A-4, supra note 8, at 39 (“Inferences and assumptions used in your analysis should be identified, and 

your analytical choices should be explicitly evaluated and adequately justified.”). 

36 See 2007 NAS Report on Global Change Assessments, supra note 15, at 126. 37 See Circular A-4, supra note 8, at 39. 
 9

consequence or dose-response relationship for the hazard of concern.38 In the 2007 NAS Report 

on the Proposed Risk Assessment Bulletin, the NAS reaffirmed that including this information 

would improve the clarity of a risk analysis and is consistent with the recommendations of 

previous expert reports.39

More recent reports have reaffirmed that, in addition to considering the full population or entities 

at risk, the risk analysis should also consider subpopulations or sub-entities that may be 

particularly susceptible to such risks and/or may experience greater exposures.40 If a risk 

analysis is to address only specific subpopulations, the scope should be very clear about this 

limitation. 

Where there are known differences in risk for different individuals, subpopulations or 

ecosystems, analysts should characterize this variability. Risk managers will be better informed 

when an understanding of variability and the key contributors to the cause of this variability are 

presented in the risk analysis.41 As guidance on the presentation of risk information to the public 

continues to develop, so too will agencies’ presentation and discussion of variability. 

The President’s Commission on Risk stated: “A good risk management decision is based on a 

careful analysis of the weight of scientific evidence that supports conclusions about a problem’s 

potential risks to human health and the environment.”42 This may include consideration of both 

positive and negative studies, in light of each study’s technical quality. Agencies and the risk 

assessment community are continuing to develop techniques for weight of evidence evaluations. 

Agencies should consider confounding and/or synergistic factors. The scientific process of 

considering these elements may assist policy makers in developing a broader sense of how risk 

can be reduced significantly and the range of decision options that need to be considered in 

developing risk management approaches.43 

 

38 See Risk Commission Report I, supra note 14, at 24 (a list of questions should be addressed in a risk 

characterization). 

39 See 2007 NAS Report on the Proposed Risk Assessment Bulletin, supra note 4, at 62. 40 See Risk Commission Report I, supra note 14, at 24 (a list of questions that includes asking about individuals or 

groups that are at risk and if some people are more likely to be at risk than others). 

41 See 2007 NAS Report on the Proposed Risk Assessment Bulletin, supra note 4, at 80 (“information on the 

variability of effects across potentially affected populations--due to differences in sensitivity, exposure, or both--is 

essential to decision-making.”). 

42 See Risk Commission Report I, supra note 14, at 23; Id. at 23-24 (“It is important that risk assessors respect the 

objective scientific basis of risks and procedures for making inferences in the absence of adequate data. Risk 

assessors should provide risk managers and other stakeholders with plausible conclusions about risk that can be 

made on the basis of the available information, along with evaluations of the scientific weight of evidence 

supporting those conclusions and descriptions of major sources of uncertainty and alternative views.”). 43 Id. at 24 (a list of questions that includes asking about “[w]hat other sources cause the same type of effects or 

risks.”). 
 10

5. Peer review of risk assessments can ensure that the highest professional standards 

are maintained. Therefore, agencies should develop policies to maximize its use.

 

Agencies should refer to the Peer Review Bulletin for updated guidance regarding agency best 

practices for peer review.44 

6. Agencies should strive to adopt consistent approaches to evaluating the risks posed 

by hazardous agents or events. 

Principles for Risk Management

1. In making significant risk management decisions, agencies should analyze the 

distribution of the risks and the benefits and costs (both direct and indirect, both 

quantifiable and non-quantifiable) associated with the selection or implementation of 

risk management strategies. Reasonably feasible risk management strategies, including 

regulation, positive and negative economic incentives, and other ways to encourage 

behavioral changes to reduce risks (e.g., information dissemination), should be 

evaluated. Agencies should employ the best available scientific, economic and policy 

analysis, and such analyses should include explanations of significant assumptions, 

uncertainties, and methods of data development. 

Agencies should refer to Circular A-4 for updated guidance regarding agency best practices for 

regulatory analysis.45

2. In choosing among alternative approaches to reducing risk, agencies should seek to 

offer the greatest net improvement in total societal welfare, accounting for a broad 

range of relevant social and economic considerations such as equity, quality of life, 

individual preferences, and the magnitude and distribution of benefits and costs (both 

direct and indirect, both quantifiable and non-quantifiable). 

Agencies should refer to Circular A-4 for updated guidance regarding agency best practices for 

regulatory analysis.46

Principles for Risk Communication

1. Risk communication should involve the open, two-way exchange of information 

between professionals, including both policy makers and “experts” in relevant 

disciplines, and the public. 

In describing its approach to risk characterization in the 1996 NAS Report on Understanding 

Risk and Informing Decisions, NAS stated that “[t]he responsible organization’s staff should 

describe the stated and implicit purposes of the decision-making activity, the type of decision 

and general aims furthered by the activity, and the intended users of the risk characterization.”47 

 

44 See Peer Review Bulletin, supra note 8. 45 See Circular A-4, supra note 8. 46 Id. 47 See 1996 NAS Report on Understanding Risk and Informing Decisions, supra note 27, at 146; Id. (“Different 

types of decisions may require different types of knowledge and perspectives and hence require different 

participants in the analytic-deliberative process--both inside and outside the organization.”). 
 11

Agencies should provide this information as it will assist the readers and users in better 

understanding the questions that the analysis sought to answer and will help to ensure that the 

risk analyses are used for their intended purposes. This information is particularly important in 

cases where likely users of the risk analyses are not the original intended audience for the 

document. 

2. Risk management goals should be stated clearly, and risk assessments and risk 

management decisions should be communicated accurately and objectively in a 

meaningful manner. 

An executive summary that discloses the objectives and scope, the key findings of the analysis, 

and the key scientific limitations and uncertainties can be an important part of risk 

communication.48 In the 2007 NAS Report on the Proposed Risk Bulletin, the NAS commented 

that the inclusion of an executive summary could improve the clarity of risk assessments.49 

Presentation of information in a helpful and concise introductory section of the report will not 

only foster improved communication of the findings, but will also help ensure that the risk 

analysis is appropriately interpreted by diverse end users. 

To maximize public understanding and participation in risk-related decisions, agencies 

should: 

a. explain the basis for significant assumptions, data, models, and inferences used 

or relied upon in the assessment or decision; 

A high degree of transparency with respect to data, assumptions, and methods will increase the 

credibility of the risk analysis, and will allow interested individuals, internal and external to the 

agency, to understand better the technical basis of the analysis.50 

b. describe the sources, extent and magnitude of significant uncertainties associated 

with the assessment or decision; 

In the 1996 NAS Report on Understanding Risk and Informing Decisions, the NAS observed 

that “[t]here is strong agreement that risk analysts should explicitly summarize uncertainty, and 

 

48 Key limitations are those that are most likely to affect significantly the determinations and/or estimates of risk 

presented in the analysis. 

49 See 2007 NAS Report on the Proposed Risk Assessment Bulletin, supra note 4, at 64 (“These qualitative 

standards . . . [presented in an executive summary] could improve the clarity of risk assessment in the federal 

government if risk assessments do not implement them already (although the existence of such problems is not 

established by the bulletin.”)). 

50 See 1996 NAS Report on Understanding Risk and Informing Decisions, supra note 27, at 67; Id. at 100 (in a good 

quantitative analysis, “[a]ny assumptions used are clearly explained, used consistently, and tested for 

reasonableness,” “[c]alculations are presented in such a form that they can be checked by others interested in 

verifying the results,” and “[u]ncertainties are indicated, including those in data, models, parameters, and 

calculations.”). See 2007 NAS Report on Global Change Assessments, supra note 15, at 126 (NAS recommends 

that “[t]here should be a deliberate effort to clarify the importance of alternative assumptions and to illustrate the 

impacts of uncertainties.”). See also U.S. Environmental Protection Agency, Science Policy Council Handbook, 

Risk Characterization 15 (2000) [hereinafter EPA Risk Characterization Handbook] (“[Transparency] ensures that 

any reader understands all the steps, logic, key assumptions, limitations, and decisions in the risk assessment, and 

comprehends the supporting rationale that lead to the outcome.”). In the EPA Risk Characterization Handbook, 

EPA lists 10 elements of full disclosure. Id. at 15-16. 
 12

there are methods for doing so.”51 In the 2007 NAS Report on Global Change Assessments, 

when referring to critical elements of a credible, legitimate and salient assessment, the NAS 

included as one of four central elements: 

Deliberative and consistent methods of treating and communicating uncertainties add 

credibility and salience. Regardless of method (statistics, sensitivity analysis, scenario 

development, or expert judgment), each measure must be defined and communicated in a 

consistent manner.52 

In the same report the NAS also stated: 

An effective characterization of uncertainty in assessments requires determining what 

sorts of uncertainty information would be useful for decision makers as well as 

developing quantitative or qualitative measures of uncertainty . . . . The manner in which 

uncertainties are acknowledged and characterized will affect both the salience and 

credibility of the assessment.”53 

The agency also should identify the sources of the underlying information (consistent with 

sensitive information and confidentiality protections) and the supporting data and models, so that 

the public can evaluate whether there may be some reason to question objectivity.54 Data should 

be accurately documented, and error sources affecting data quality should be identified and 

disclosed.55 

c. make appropriate risk comparisons, taking into account, for example, public 

attitudes with respect to voluntary versus involuntary risk; and, 

When making risk comparisons, agencies should be careful to consider the perspectives, 

assumptions, attitudes and context that the public associates with each risk. Agencies may want 

to consult the risk communication literature when considering appropriate comparisons. 

Although the risk assessor has considerable latitude in making risk comparisons, the fundamental 

point is that risk should be placed in a context that is useful and relevant for the intended 

audience.56 Furthermore, effective communication of risk information can assist the public in 

 

51 See 1996 NAS Report on Understanding Risk and Informing Decisions, supra note 27, at 107 (“When uncertainty 

is recognizable and quantifiable, the language of probability can be used to describe it.”). See also EPA Risk 

Characterization Handbook, supra note 50, at 41 (“While it is generally preferred that quantitative uncertainty 

analyses are used in each risk characterization, there is no single recognized guidance that currently exists on how to 

conduct an uncertainty analysis. Nonetheless, risk assessors should perform an uncertainty analysis . . . . 

Uncertainty analysis should not be restricted to discussion of precision and accuracy, but should include such issues 

as data gaps and models.”). 

52 See 2007 NAS Report on Global Change Assessments, supra note 15, at 60. 53 Id. at 126. 54 See Information Quality Guidelines, supra note 8. 55 See OMB, Statistical Policy Working Paper No. 31, Measuring and Reporting Sources of Error in Surveys, 1-5 

(2001) (“The measurement and reporting of error sources is important for everyone who uses statistical data. For 

the analyst, this information helps data analyses through an awareness of the limitations of the data.”), available at

http://www.fcsm.gov/01papers/SPWP31_final.pdf . 56 See National Research Council, National Academy of Sciences, Improving Risk Communication 165-79 (1989). 

See also Risk Commission Report I, supra note 14, at 4 (the problems a regulation is intended to address should be 

placed in their “public health and ecological context.”). 
 13

balancing benefits and risks.57 As our understanding regarding the presentation of risk 

information to policy makers and the public continues to develop, so too will agencies’ 

presentation and discussion of risk comparison information. 

d. provide timely, public access to relevant supporting documents and a reasonable 

opportunity for public comment. 

Agencies should refer to OMB’s Final Bulletin for Agency Good Guidance Practices, as well as 

the Peer Review Bulletin, for updated guidance regarding best practices for increasing public 

access and public comment concerning guidance documents and influential scientific 

information.58 In addition, as noted in the OMB Information Quality Guidelines, influential risk 

analyses should be reproducible. 59 For guidance on how to provide the public with timely 

access to government information, Agencies should refer to OMB’s Circular A-130, which 

addresses the management of Federal information resources, and OMB Memorandum 06-02, 

which addresses improving public access to Federal information.60

Principles for Priority Setting Using Risk Analysis

1. To inform priority setting, agencies should seek to compare risks, grouping them in 

broad categories of concern (e.g., high, moderate, and low). 

2. Agencies should set priorities for managing risks so that those actions resulting in the 

greatest net improvement in societal welfare are taken first, accounting for relevant 

management and social considerations such as different types of health or 

environmental impacts; individual preferences; the feasibility of reducing or avoiding 

risks; quality of life; environmental justice; and the magnitude and distribution of both 

short- and long-term benefits and costs. 

3. The setting of priorities should be informed by internal agency experts and a broad 

range of individuals in state and local government, industry, academia, and 

nongovernmental organizations, as well as the public at large. Where possible, 

consensus views should be reflected in the setting of priorities. 

4. Agencies should attempt to coordinate risk reduction efforts wherever feasible and 

appropriate. 

 

57 See Institute of Medicine, National Academy of Sciences, Seafood Choices: Balancing Benefits and Risks 207 

(2006) (“In the committee’s judgment, it is important to conduct substitution analyses of the potential impacts of 

changes in consumption despite the uncertainties about the underlying nutrient and contamination levels.”). Id. at 

231 (in referring to guidance and information that can simplify such tradeoffs, the NAS lists considerations for 

guidance development). 

58 See OMB, Final Bulletin for Agency Good Guidance Practices (2007), available at

http://www.whitehouse.gov/omb/fedreg/2007/012507_good_guidance.pdf, and Peer Review Bulletin, supra note 8. 

59 See Information Quality Guidelines, supra note 8, 67 Fed. Reg. at 8460 (independent reanalysis of the original or 

supporting data using the same methods would generate similar analytical results, subject to an acceptable degree of 

precision). 

60 See OMB, Circular A-130, Management of Federal Information Resources (2000), available at

http://www.whitehouse.gov/omb/circulars/a130/a130trans4.pdf; OMB Memorandum No. 06-02, Improving Public 

Access to and Dissemination of Government Information and Using the Federal Enterprise Architecture Data 

Reference Model (2005), available at http://www.whitehouse.gov/omb/memoranda/fy2006/m06-02.pdf.