National Academies Press: OpenBook

WIC Nutrition Risk Criteria: A Scientific Assessment (1996)

Chapter: 8 Conclusions and Recommendations

« Previous: 7 Predisposing Nutrition Risk Criteria
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 335
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 336
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 337
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 338
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 339
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 340
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 341
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 342
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 343
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 344
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 345
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 346
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 347
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 348
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 349
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 350
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 351
Suggested Citation:"8 Conclusions and Recommendations." Institute of Medicine. 1996. WIC Nutrition Risk Criteria: A Scientific Assessment. Washington, DC: The National Academies Press. doi: 10.17226/5071.
×
Page 352

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

CONCLUSIONS AND RECOMMENDATIONS 335 8 Conclusions and Recommendations The concept of nutrition risk assessment is integral to the design and operation of the WIC program. Nutrition risk is a criterion for program eligibility, and nutrition risk criteria are used to assign a priority level to women, infants, and children. By serving those at the highest priority levels first, the WIC priority system is used to allocate limited program resources among eligible individuals. In addition, the nutrition risk assessments are used to tailor the WIC intervention and, in some cases, to monitor the health and nutrition status of program participants. This report is a scientific assessment of the WIC nutrition risk criteria as they are currently used to establish WIC eligibility and the priority of the WIC eligible individuals. Based on this scientific assessment, this final chapter provides general conclusions, recommendations for specific nutrition risk criteria, and recommendations for future research and action. The framework that was used in the scientific assessment conducted for this report has two key features. The first is the exposition and utilization of the concept of potential to benefit from the delivery of interventions and services provided by the WIC program. This concept differs from the approach that has guided the development of risk criteria used by the WIC program, namely, assessment of the individual's risk of a poor outcome. This application of the concept of potential to benefit moves the program focus from curative (tertiary prevention) to risk reduction (secondary prevention). Utilizing such an approach can provide for more efficient targeting of the scarce resources available to the WIC program and also improve outcomes. A second important feature of the analytical framework is the explicit consideration of the concepts of yield of risk, yield of benefit, and sensitivity of the

CONCLUSIONS AND RECOMMENDATIONS 336 nutrition risk criteria used by the WIC program. These concepts, in conjunction with the concepts of indicators of risk and indicators of benefit, have implications that underlie both the assessments of the nutrition risk criteria used by the WIC program and the development of the report's conclusions and recommendations. In particular, risk indicators and cutoff points should be chosen such that the highest proportion of those who are truly at risk can be identified and the highest proportion of those identified can benefit from WIC program participation. With limited program resources, cutoff points should be set with less than perfect sensitivity to increase yield, recognizing that as cutoff points become more restrictive, some individuals who could benefit from WIC services will not be served. The decision process presented in Chapter 3 can be used to review other risk criteria that the WIC program may be asked to approve in the future. GENERAL CONCLUSIONS The committee reached seven general conclusions about the WIC nutrition risk criteria and priority system: • A body of scientific evidence supports a majority of the nutrition risk criteria used by the WIC program. For some of the risk criteria, however, there are serious gaps in the evidence. • Nutrition risk criteria used by many states have a high sensitivity and low yield of benefit. This is because the prevalence of many of the risk conditions is low and the cutoffs used are generous, resulting in both the selection of many of those who have the risk condition (high sensitivity) and the selection of many individuals who do not have the risk condition (low yield of risk, which results in low yield of benefit). • Use of generous cutoff points or loosely defined conditions in categories designated by federal regulation to receive high priority for eligibility may result in denial of services to individuals who are actually at higher nutrition risk. When resources are limited, individuals in lower priority categories may not be served even if their true risk is very high, while those in high priority categories must be served. Very generous cutoff points produce a low yield of benefit without any increase in sensitivity (serving more of those truly at risk). Loosely defined risk conditions are those that encompass a broad range of medical problems with varying degrees of nutrition risk or potential to benefit from WIC participation. Such loosely defined nutrition risk criteria include endocrine disorders, renal disease, chronic and recurrent infections, food allergies, and genetic and congenital disorders. • There is some inconsistency between the WIC program's goals, design, and implementation. The goal of the WIC program is one of primary prevention —to prevent the occurrence of health problems. Through the use of nutrition

CONCLUSIONS AND RECOMMENDATIONS 337 risk criteria, the WIC priority system is designed in principle to be a secondary/tertiary prevention program to reduce or cure identified risk. However, through the use of generous cutoff points, loosely defined risk conditions, and a priority system that places pregnant women and infants at the highest priorities, in general, the WIC program operates as a primary prevention program for pregnant women and infants and a secondary and tertiary prevention program for children and postpartum women. • The WIC priority system should be reexamined. Many individuals now classified in low priority categories have more potential to benefit from WIC services than some individuals placed in higher priority categories. For example, a child of a mentally retarded parent (currently priority VII) or an anemic child age 3 years with a very low hemoglobin (currently priority III) may have a greater potential to benefit than an infant classified as anemic (currently priority I) by a criterion with a too generous cutoff point. • It is important that the WIC program reevaluate the criteria in use every 5 to 10 years and change cutoffs and incorporate new criteria as necessary. This is because the yield of risk of a criterion increases as the prevalence of the risk in the population increases, and it decreases as the prevalence of the risk in the population decreases. For example, the yield of risk of the nutrition risk criterion for poor growth has decreased over time as the prevalences of wasting and stunting have declined. The addition of homelessness as a nutrition risk criterion by the WIC program reflects, in part, increases in the prevalence of homelessness. • There is a need to identify or develop additional nutrition risk criteria that select those individuals who are at risk of developing specific health and nutrition problems if they do not receive WIC benefits. Since the WIC program is believed to be a major contributor to the decline in the prevalence of health and nutrition problems (for example, iron deficiency anemia), it is important to identify practical indicators of the risk of developing the problem so that the WIC program can maintain its preventive function. Dietary risk criteria or predisposing risk criteria may do this, but data are limited. Setting high cutoff points for anemia or poor growth does not effectively identify those at risk of developing the problem. In addition, the committee emphasizes the importance of the systematic collection of data about the prevalence of individuals meeting specific WIC nutrition risk criteria. RECOMMENDATIONS FOR SPECIFIC NUTRITION RISK CRITERIA Table 8-1 summarizes the committee's recommendations for use of nutrition risk criteria, cutoff values, and the segments of the population to which they apply. For greater specificity, the name of the criterion used occasionally

CONCLUSIONS AND RECOMMENDATIONS 338

CONCLUSIONS AND RECOMMENDATIONS 339

CONCLUSIONS AND RECOMMENDATIONS 340

CONCLUSIONS AND RECOMMENDATIONS 341

CONCLUSIONS AND RECOMMENDATIONS 342

CONCLUSIONS AND RECOMMENDATIONS 343

CONCLUSIONS AND RECOMMENDATIONS 344

CONCLUSIONS AND RECOMMENDATIONS 345

CONCLUSIONS AND RECOMMENDATIONS 346 differs from that used by the WIC program. The recommendations are intended to apply to all states unless otherwise indicated. Exceptions may be made if the meaning of the criterion in a particular context is different or the condition (e.g., pica) is common in one state and uncommon in another. Brief supplementary information about these recommendations follows for each of the categories of nutrition risk criteria. The full report provides the basis for each recommendation. For convenience, Table 8-2 lists those nutrition risk criteria that the committee recommends adding and those that it recommends discontinuing. Anthropometric Risk Criteria Anthropometric risk criteria are used in the WIC program to assess individuals for nutrition risk and to monitor their nutrition status or their response to WIC program interventions over time. The committee's review indicated that the WIC anthropometric risk indicators are predictors both of nutrition and health risks and of benefit from participation in the WIC program. The cutoff points used for anthropometric risk indicators among WIC programs vary substantially, however, with resulting effects on yield. Therefore, the committee recommends that cutoff points for anthropometric measures be limited to those that are scientifically justified. It further points out that there is no obvious justification for the use of symmetric cutoff points (for example, at the 5th and 95th percentiles). Risk criteria for which there was very little evidence of nutrition risk or benefit from WIC participation include maternal short stature, abnormal postpartum weight change, and infants large for gestational age. Therefore, the committee recommends discontinuing use of these nutrition risk criteria. Biochemical and Other Medical Risk Criteria In general, the biochemical and other medical risk criteria predict nutrition and health risk, with varying degrees of benefit. The most common concern of the committee was the lack of scientific justification for the generous cutoff points for biochemical and certain other medical risk criteria currently used by many state WIC agencies. Of the biochemical and other medical risk criteria, anemia is used most frequently in the WIC program to establish the eligibility of women, infants, and children to participate in the program. Cutoff values for anemia vary substantially among state WIC agency programs, with little or no scientific justification for variation from standard definitions. The committee recommends

CONCLUSIONS AND RECOMMENDATIONS 347 that anemia continue to be used as a risk criterion in the WIC program but discourages the use of high cutoff points because of the resulting low yield from increasing their iron intake. That is, the high cutoff values for anemia used by many state WIC programs result in the inclusion of many who do not have and are not at risk of anemia and, thus, are unlikely to benefit from provision of WIC's supplemental food. TABLE 8-2 Committee Recommendations for Changes in Risk Criteria Nutrition Risk Criteria That Should Be Added: Dietary Food insecurity Predisposing Maternal depression Nutrition Risk Criteria That Should Not Be Used: Anthropometric Maternal short stature Large for gestational age Abnormal postpartum weight change Medical Arthritis, general Asthma Bronchitis Food intolerance, except lactose intolerance High parity History of neonatal loss History of postterm delivery Nausea and vomiting, mild Otitis media Placental abnormalities Preeclampsia and eclampsia Pregnancy age older than 35 years Prematurity for children Pyloric stenosis Upper respiratory infection Urinary tract infection except chronic pyelonephritis with persistent proteinuria Dietary Inadequate diet Excessive caloric intake Excessive caffeine intake Vegetarian diets except vegan Predisposing Passive smoking Many biochemical and other medical nutrition risks are documented as the result of diagnosis by a medical care provider of an existing medical condition

CONCLUSIONS AND RECOMMENDATIONS 348 that affects nutritional needs or may be improved by dietary management. These diagnosed conditions are reported to WIC program staff. The committee recommends that most of these nutrition risk criteria continue to be used in the WIC program, using cutoff points that generally are documentation or diagnosis of the disease or disorder. Maternal cigarette, alcohol, and drug use among pregnant and lactating women pose significant health risks but uncertain benefit from participation in the WIC program. On an interim basis, the committee recommends that these nutrition risk indicators be used in the WIC program, with a cutoff of ''any use."1 Risk criteria for which there was risk and benefit only under specific conditions included long-term drug-nutrient interactions and chronic and recurrent infections. The committee feels that these criteria were too vague to be useful in their current form. It recommends that a listing of drugs for which there are clear drug-nutrient interactions or potential for misuse be developed. The use of other medications would not be associated with nutrition risk or benefit, and thus their use would not provide a basis for eligibility. For chronic and recurrent infections, evidence of risk and benefit was available only for certain chronic infections for which there were documented nutrition deficits, and the committee recommends that states should clearly define "chronic" or "recurrent" in determining cutoff points for these indicators. Risk criteria for which there was very limited evidence of nutrition risk or benefit from participation in the WIC program included food intolerance other than lactose intolerance, high age at conception, previous placental abnormalities, history of postterm delivery, high parity, preeclampsia and eclampsia, and prematurity as a risk criterion for children ages 1 to 5 years. The committee recommends that these nutrition risk criteria no longer be used in the WIC program. Dietary Risk Criteria Three major categories of dietary risk criteria are reviewed: inappropriate dietary patterns, inadequate diets, and food insecurity. Risk criteria classified as inappropriate dietary patterns are listed in Table 8-1. The committee found that there are clear health and nutrition risks associated with selected inappropriate dietary patterns and that the potential to benefit from participation in the WIC program is high. For women and for children at least 2 years of age, failure to 1 Three committee members preferred to set higher cutoff points that would more clearly delineate women whose substance use places them at higher risk for poor outcomes. Barbara Abrams and Barbara Devaney preferred to set higher cutoff points for cigarette and alcohol use; Roy Pitkin preferred a higher cutoff point only for alcohol use.

CONCLUSIONS AND RECOMMENDATIONS 349 meet Dietary Guidelines for Americans is a dietary risk criterion that receives increased attention in this report. As long as the food provided by the supplemental food package is eaten, the WIC program is likely to improve the diets of those WIC participants with inadequate diets. In the WIC setting, however, diet recalls and food frequency questionnaires that compare estimated nutrient intake with Recommended Dietary Allowances have poor ability to ascertain who actually has inadequate diets. Thus, even though the WIC program is likely to improve dietary intake, the committee recommends discontinuing use of inadequate diets as a nutrition risk criterion because it has a very low yield. Nonetheless, diet recalls or food frequency questionnaires are useful in the WIC program for identifying foods commonly consumed and providing a starting point for nutrition education. Food insecurity is defined as the lack of predictable, sustainable access in socially acceptable ways to enough food of adequate quality to sustain health. Although this risk criterion is just beginning to be used by state WIC agencies, and there is limited evidence to evaluate causal links to nutrition and health risk, the committee believes that there is a fundamental value to addressing the risk to health and nutrition related to a lack of access to food. The benefit of participation in the WIC program for those at risk of food insecurity is high. Therefore, the committee recommends use of food insecurity as a nutrition risk criterion in the WIC program. At present, however, there is insufficient scientific evidence on which to select a cutoff point that would identify those most likely to benefit from the WIC program. Predisposing Nutrition Risk Criteria Currently, predisposing nutrition risk criteria receive a low priority within the WIC program. The use of predisposing nutrition risk criteria warrants additional attention. If an individual has a predisposing risk but no other risk, he or she will be placed in a priority category that is usually unserved by the WIC program. This may limit the WIC program's ability to serve as a preventive program. Additional attention to the predisposing nutrition risk criteria is warranted because (1) they have a high yield for risk and a high, but as yet unknown, potential for benefit from WIC services, and (2) the prevalence of some of these factors (e.g., homelessness) is increasing, thus increasing the overall yield of these criteria. The committee supports the use of most of the predisposing risk criteria that have been used in the WIC program for women, infants, and children (see Table 8-1). The committee recommends that a diagnosis of depression be added as a predisposing risk criterion for women, and that diagnosed maternal depression be added as a predisposing risk criterion for infants and children. Because of the

CONCLUSIONS AND RECOMMENDATIONS 350 lack of evidence that nutrition will benefit those exposed to passive smoking, the committee recommends that this risk criterion no longer be used in the WIC program. RECOMMENDATIONS FOR FUTURE RESEARCH AND ACTION Research Recommendations Regarding the nutrition risk criteria reviewed in the report, the committee recommends the following areas for future research: • Develop anthropometric standards (including weight change velocity) for pregnant and lactating women, including adolescents. These standards should be suitable to assess the likelihood that these women would benefit from nutrition intervention and to achieve improved reproductive outcomes. • Evaluate whether the use of a combination of criteria (e.g., an anthropometric risk criterion plus a dietary risk criterion) may be more effective than the use of a single risk criterion in predicting a benefit from participation in the WIC program. • Evaluate whether overweight or obese mothers and their infants and children benefit from current WIC program interventions. The prevalence of overweight and obesity among low-income women, infants, and children is increasing over time, and the health and nutrition risks of obesity are well- documented. • Evaluate the yields of benefit for the various cutoff points used for anthropometric risk criteria—recognizing that there is no obvious justification for symmetric high and low cutoff points. It is possible that current cutoff points are so generous that the yield of benefit from WIC program interventions is low. • Examine how the WIC program affects nutrition outcomes for individuals with selected medical risk factors. • Determine the extent to which women who use cigarettes, alcohol, and/or illegal drugs benefit from the WIC program and the level of use of these substances that should be set as the cutoff point, if applicable. • Invest in the development and validation of practical dietary assessment instruments that can be used across WIC programs for the identification of inappropriate dietary patterns, inadequate dietary intake, and food insecurity, recognizing that adaptations may be needed for culturally diverse populations. • Examine the utility of predisposing factors (such as homelessness, migrancy, low level of maternal education, child abuse and neglect, and maternal depression) as predictors of benefit from WIC program services.

CONCLUSIONS AND RECOMMENDATIONS 351 Action Recommendations In addition to these research recommendations, the committee recommends the following actions be taken by the Food and Consumer Service, U.S. Department of Agriculture, to provide guidance to state WIC agencies in the development of nutrition risk criteria: • Adopt scientifically justified cutoff values for anemia and for anthropometric criteria among women, infants, and children, realizing that they may be different across populations as prevalences change. • Define preterm consistently as delivery before the end of the 37 th post- menstrual week for both mothers and their infants. • Adopt scientifically justified cutoff points for young maternal age (chronological or gynecological, or both), because increased risks associated with births to these women cannot be entirely explained by poverty. • Distinguish among some of the broadly defined medical and dietary conditions used by the WIC program in order to identify eligible WIC participants truly at high nutrition risk. These broad nutrition risk categories include endocrine disorders, renal disease, chronic and recurrent infections, food allergies, and genetic and congenital disorders. They include a broad range of medical problems with varying degrees of nutrition risk or potential to benefit from participation in the WIC program. Similarly, the category inappropriate diet includes some behaviors for which little nutrition risk is evident. The list in Table 8-1 distinguishes among criteria in the broad nutrition risk categories. • Appoint an expert committee to provide guidance on cutoff points for cigarette, alcohol, and illegal drug use that will identify pregnant and lactating women who are most likely to benefit from the WIC program. Members of the expert committee should have expertise in substance abuse during pregnancy and lactation, assessment and treatment of substance abuse, public policy, nutrition, and epidemiology. • Identify the specific drugs that place individuals at nutrition risk with prolonged use and for which WIC program interventions could provide some benefit. The current nutrition risk criteria drug-nutrient interactions and inappropriate use of medications are too broadly defined and likely to produce very low yield of benefit. • Disseminate information about risk criteria widely. • Consider changing the current WIC priority system to give higher priority to those nutrition risk criteria identified in this report as having strong relationships to risk and potential to benefit and lower priority to nutrition risk criteria with weaker relationships to risk and potential to benefit.

CONCLUSIONS AND RECOMMENDATIONS 352 1. Risk criteria that merit higher priority: vegan diets, highly restrictive diets, selected aspects of inappropriate infant feeding, food insecurity, homelessness, child of a mentally retarded parent. 2. Risk criteria that merit higher priority among children: nutrient deficiency diseases, failure to thrive, gastrointestinal disorders, inborn errors of metabolism. 3. Risk criteria that merit lower priority: mild nausea and vomiting during pregnancy; lack of prenatal care; cigarette, alcohol, and illegal drug use.2 Such a change in the priority system would require disaggregating the current categories (anthropometric, medical, dietary, and predisposing) that are used for ranking each risk criterion into one of seven priorities. It would also mean that in some cases children could be given priority over pregnant women. Such a change should improve the targeting of the program in terms of both risk and benefit. 2 Three committee members (Barbara Abrams, Barbara Devaney, and Roy Pitkin) prefer retaining high priority for the criteria alcohol use and illegal drug use. Barbara Abrams and Barbara Devaney prefer retaining the high-priority level for the criterion cigarette use as well. See footnote 1 concerning cutoff points for these criteria.

Next: Appendix A Participants at the First Public Meeting May 19, 1994 »
WIC Nutrition Risk Criteria: A Scientific Assessment Get This Book
×
 WIC Nutrition Risk Criteria: A Scientific Assessment
Buy Paperback | $53.00 Buy Ebook | $42.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

This book reviews the scientific basis for nutrition risk criteria used to establish eligibility for participation in the U.S. Department of Agriculture's Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). The volume also examines the specific segments of the WIC population at risk for each criterion, identifies gaps in the scientific knowledge base, formulates recommendations regarding appropriate criteria, and where applicable, recommends values for determining who is at risk for each criterion. Recommendations for program action and research are made to strengthen the validity of nutrition risk criteria used in the WIC program.

READ FREE ONLINE

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!