Environmental Decisions in the Face of Uncertainty (2013) / Chapter Skim
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4 Uncertainty and Decision Making: Lessons from Other Public Health Contexts
4 Uncertainty and Decision Making: Lessons from Other Public Health Contexts
Pages 107-146
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From page 107... ...
. However, not all of those interventions were unanimously accepted when first proposed or implemented, primarily due to uncertainties surrounding the possible benefits, risks, costs, feasibility, and public values.
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From page 108... ...
agencies play important public health roles that involve weighing evidence and taking into account uncertainties in the making of a policy or regulatory decision that affects public health. Table 4-1 summarizes the processes and methods used by different public health agencies and organizations to evaluate the human health risks and benefits and other factors influencing the decisions, along with their inherent uncertainties.
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From page 109... ...
depending on the nature of The uncertainty analyses of human the exposure (for example, health risk estimates often includes inhalation exposure vs. the uncertainties in the ingestion)
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. estimates of human health risks and benefits.
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WHO–FAO Has published detailed Detailed discussions of the guidance and assessments for uncertainties in estimates of microbial risk characterization health risks and analyses of those in food that include uncertainties. Some assessments qualitative, semiquantitative, discuss economic factors in decisions, and quantitative human including uncertainties in economic health risk assessments.
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and the Center for Food Safety and Nutrition (CFSAN) at FDA have published -- individually and jointly -- a number of assessments of the health risks associated with chemical or biological agents in different foods.
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The committee did not attempt to develop a thorough evaluation or critique of each case; rather, it focused on aspects of the different cases that demonstrate useful approaches to evaluating and considering uncertainty in regulatory or policy decisions.2 SECONDHAND SMOKE Smoking bans that limit exposures to secondhand smoke (SHS) have been enacted in many places despite some stakeholders pointing to uncertainties in economic and other data as well as to uncertainties in estimates of health risks as a reason not to enact bans.
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From page 114... ...
. Similarly, public comment periods on health risk assessments and proposed policies and regulations were often dominated by individuals or groups criticizing the studies who were often allied with the tobacco industry, and tobacco industry documents indicate that they had a strategy of maintaining the scientific debate around the health effects of secondhand smoke (Bryan-Jones and Bero, 2003)
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From page 115... ...
Legislatures were left to make decisions on environmental controls for SHS exposure in the face of large uncertainty and intense lobbying. As smoking bans were enacted and implemented, studies have looked at the economic consequences of the bans, for example, on restaurants and bars (Glantz and Charlesworth, 1999)
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From page 116... ...
Researchers took advantage of some of those bans to investigate whether they were associated with any health effects, to study the public reaction to the bans, and to see whether the bans had any economic consequences on establishments covered by the bans. Epidemiology studies indicated that smoking bans or restrictions were associated with decreases in adverse cardiovascular events (Barone-Adesi et al., 2006; Bartecchi et al., 2006; Cesaroni et al., 2008; IOM, 2010a; Juster et al., 2007; Khuder et al., 2007; Lemstra et al., 2008; Pell et al., 2008; Sargent et al., 2004; Seo and Torabi, 2007; Vasselli et al., 2008)
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monocytogenes. In this section, the committee discusses that risk assessment and the uncertainty analyses in it and also discusses how FDA has used the results of that risk assessment to refine its policies around the control of L
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From page 118... ...
. Human Health Risks The 2003 FDA/FSIS risk assessment was designed to predict the relative risk of listeriosis from eating certain ready-to-eat foods among people in three age-based groups: perinatal (16 weeks after fertilization to 30 days after birth)
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. Rather than providing a single risk estimate, the health risk assessment provided a range of estimates using sensitivity analyses and probabilistic methods for the different food categories, the populations with different susceptibilities to listeriosis, and the strains of L
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From page 120... ...
Decisions in the Face of Uncertainty: Lessons Learned The assessment of L monocytogenes and FDA's use of that assessment highlight how analyses of health risks that account for uncertainties -- such as those for different food types, different storage conditions, and different susceptible populations -- can provide decision makers with information to help design policies that target mitigation strategies to the greatest risks, either for specific foods with a higher likelihood of being associated with human illness, or for populations that are more susceptible to illness.
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From page 121... ...
For example, deli meats are considered very high risk because they were in the high cluster for both per-serving and per-annum consumption. BOVINE SPONGIFORM ENCEPHALOPATHY Bovine spongiform encephalopathy (BSE)
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From page 122... ...
For example, the sensitivity analyses demonstrated that the model is very sensitive to the rate of either accidental or intentional misfeeding of cattle with feed containing ruminant protein but that there is a large uncertainty in the rate at which that misfeeding occurs. Changing the incubation time also affects the model outputs; TABLE 4-2 Estimates of Infected Cases of BSE in the 20 Years Following Introduction of 500 Infected Animals into the United States Percentile Label Mean 5th 25th 50th 75th 95th Base Case 180 33 98 160 240 400 Sensitivity 1 200 38 110 180 270 440 Sensitivity 2 2,600 1,200 1,900 2,500 3,200 4,400 Sensitivity 3 240 38 130 210 330 530 Sensitivity 4 180 33 97 160 240 400 Sensitivity 5 190 36 100 170 260 420 Sensitivity 6 43 6 13 24 60 130 Sensitivity 7 180 33 97 160 240 400 Sensitivity 8 180 33 97 160 240 400 NOTES: Explanations of the sensitivity analyses: Sensitivity 1 – Pessimistic MBM/feed production mislabeling and contamination assumptions Sensitivity 2 – Pessimistic misfeeding assumptions Sensitivity 3 – Pessimistic render reduction factor assumptions Sensitivity 4 – Higher assumed beef on bone consumption rates Sensitivity 5 – Pessimistic antemortem inspection BSE detection rates Sensitivity 6 – Longer incubation period Sensitivity 7 – Evaluate the importance of the proportion of cattle showing no clinical signs of diseases that are nonambulatory Sensitivity 8 – Evaluate the importance of the proportion of clinical animals that are nonambulatory Abbreviations: BSE = bovine spongiform encephalopathy; MBM = meat and bone meal.
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From page 123... ...
Economic Factors and Public Sentiment FSIS implemented a number of rules to protect the public's health in the wake of finding a BSE-positive cow in the United States,4 and it also conducted a regulatory impact analysis of those rules. The analyses used probabilistic models to estimate the "costs and revenues changes (a partial budget analysis)
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From page 124... ...
The agency's actions demonstrate an adaptive management process used in the face of deep uncertainty about the health risks of BSE and the appropriate mitigation strategies necessary to protect against it. FSIS implemented emergency regulations and modified them, as appropriate, after a full regulatory impact assessment was conducted.
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. When the contamination occurred, there was a great deal of uncertainty surrounding the human health risks from melamine.
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. Infant Formula In September 2008 FDA learned that some infant formula from a Chinese manufacturer might contain melamine.
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From page 127... ...
Decisions in the Face of Uncertainty: Lessons Learned As was the case in the contamination of the food supply with melamine, agencies sometimes have to make regulatory decisions in the face of deep uncertainties about the health risks and -- because of the potential for imminent public health consequences -- with little or no time to investigate those risks. The responses to contamination of the food supply demonstrate how, even in the absence of probabilistic modeling of uncertainty, a human health risk assessment can provide information for an important regulatory decision.
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From page 128... ...
Premarketing Benefit and Risk Assessments Before a pharmaceutical can be marketed, it must undergo a lengthy approval process involving the review of clinical trial data on efficacy, toxicity data, and pharmacokinetic profiles. But the information available, especially related to the safety of the drug, is limited at the time of approval.
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As is typically the case given the nature of the data for evaluating drugs, no formal quantitative uncertainty analysis was conducted. In describing the uncertainty, the director of FDA's Center of Drug Evaluation and Review (CDER)
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Those documents present a detailed analysis of the uncertainties in data and the differing opinions that agency scientists had about the policy options available to the agency decision makers. FDA decision makers, in the absence of quantitative analyses of those uncertainties beyond the presentation of different scientific opinions, made the regulatory decision.
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From page 131... ...
Those decisions might have to be made for relatively low-probability, high-consequence events, such as vaccinations to avoid a pandemic, as well as for relatively highprobability events with potentially high consequences, such as vaccinations to prevent infection with the human papillomavirus (HPV) ,7 the causative agent for cervical cancer.
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From page 132... ...
Because of the time period required to develop and administer a vaccine, decisions about how to respond to emerging information occur with great uncertainty about various issues, such as whether the strain identified is circulating widely, whether it is a strain that would incur serious morbidity and mortality, whether a vaccine could be developed in time to mitigate the virus, whether the vaccine would be safe, and whether citizens would get vaccinated. LESSONS FROM HISTORY The government's swine flu program that began in March 1976 and ended in March 1977 illustrates some of the problems of making decisions when there is great uncertainty.
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. The uncertainty about vaccine availability has also led to intensive efforts to model the effects of community containment (such as school closures, the discouragement of public gatherings, and such hygienic measures as the use of respiratory masks and advice about hand washing)
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The Human Papillomavirus Vaccine During the past 20 years researchers have identified HPV as the causative agent in cervical cancer and have characterized the virus and its components (see IOM, 2010b, for an overview) , and pharmaceutical companies have developed, tested, and marketed a vaccination against the virus (Baer et al., 2002; Carter et al., 2000; Harper et al., 2004; Harro et al., 2001; Petter et al., 2000)
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From page 135... ...
conducted sensitivity analyses for various factors, including the optimal vaccination age, universal vaccination of adolescent girls versus targeting high-risk girls, the probabilities of occurrence and progression of HPV, squamous cell lesions and cervical cancer, the probability of death, and the costs and quality of life with various health states. Elbasha et al.
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. CDC's ACIP was faced with making recommendations about whom and when to vaccinate with a newly available, but expensive, vaccine against HPV that could prevent cervical cancer.
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Decisions in the Face of Uncertainty: Lessons Learned The USPSTF guidelines demonstrate how, for some types of decisions, simple, qualitative descriptions of the uncertainty can be helpful for the decisions. KEY FINDINGS • Some agencies, such as FSIS and FDA, have conducted quantitative uncertainty analyses on public health estimates.
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From page 138... ...
That decision also highlights how quantitative uncertainty analyses are not always needed to make an informed decision. • All of these examples provide some characterization of uncertainty -- some quantitative, some qualitative, some using safety factors -- some in public health factors only and some in costs and economic impacts as well.
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2000. Comparison of human papillomavirus types 16, 18, and 6 capsid antibody re sponses following incident infection.
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2011b. Recommendations on the use of quadrivalent human papillomavirus vaccine in males -- Advisory Committee on Immunization Practices (ACIP)
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http://www. fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ ucm226956.htm (accessed January 2, 2013)
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2003b. Quantitative assessment of relative risk to public health from foodborne Listeria monocytogenes among selected categories of ready-to-eat foods.
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2011. Prevalence of genital human papillomavirus among females in the United States, the National Health and Nutrition Examination Survey, 2003–2006.
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2007. Quadrivalent human papillomavirus vaccine.
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2004. Evaluating human papillomavirus vaccination programs.
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