Annual Review of Public Health - Volume 34, 2013

A new science of human development is emerging, which has the capacity to transform the way we understand the origins of health and disease; to increase the public health significance of early child development; and to call into question how and when society should act on a range of health problems. It builds on the multidisciplinary evidence that social environments and experiences during sensitive periods in brain and biological development affect health for the balance of the life course through a process called biological embedding. Despite the fact that biological embedding has established credibility in the scientific literature, the transformative power of the new science has yet to be fully realized in policy and practice. To further this transformation, this symposium offers a public health perspective on biological embedding.

Maturation of long-running birth cohort studies has fostered a life course approach to adult health, function, and disease and related to conceptual frameworks. Using broad concepts of human development including physical, cognitive, and emotional function, birth cohorts provide insights into the processes across the life course and between generations that link to adult outcomes. We discuss findings on the determinants and health consequences of lifetime trajectories of body size, cognitive and emotional function, and socioeconomic position. Findings from the studies suggest that, for some adult health outcomes, explanations will be incomplete unless exposures and processes from across the life course are taken into account. New birth cohort studies are poised to delineate further the nature and timing of life course relationships in contemporary generations of children.

Exposure to toxic stress accelerates the wear and tear on children's developing bodies and leaves a lasting mark on adult health. Prior research has focused mainly on children exposed to extreme forms of adversity, such as maltreatment and extreme neglect. However, repeated exposure to less severe, but often chronic stressors is likely to play as large, if not larger, of a role in forecasting children's future mental and physical health. New tools from neuroscience, biology, epigenetics, and the social sciences are helping to isolate when and how the foundations for adult health are shaped by childhood experiences. We are now in the position to understand how adversity, in both extreme and more mundane forms, contributes to the adult health burden and to identify features in children's families and environments that can be strengthened to buffer the effects of toxic stressors. We are also positioned to develop and implement innovative approaches to child policy and practice that are rooted in an understanding of how exposure to toxic stressors can become biologically embedded. The stage is set for the creation of new interventions—on both grand and micro scales—to reduce previously intractable health disparities.

Health consequences of relative or absolute poverty constitute a definitive area of study in social medicine. As demonstrated in the extreme example of the Dutch Hunger Winter from 1944 to 1945, prenatal hunger can lead to adult schizophrenia and depression. A Norwegian study showed how childhood poverty resulted in a heightened risk of myocardial infarction in adulthood. In England, a study of extended impaired prenatal nutrition indicated three different types of increased cardiovascular risk at older ages. Current animal and human studies link both adverse and enriched environmental exposures to intergenerational transmission. We do not fully understand the molecular mechanisms for it; however, studies that follow up epigenetic marks within a generation combined with exploration of gametic epigenetic inheritance may help explain the prevalence of certain conditions such as cardiovascular disease, schizophrenia, and alcoholism, which have complex etiologies. Insights from these studies will be of great public health importance.

Causal inference has a central role in public health; the determination that an association is causal indicates the possibility for intervention. We review and comment on the long-used guidelines for interpreting evidence as supporting a causal association and contrast them with the potential outcomes framework that encourages thinking in terms of causes that are interventions. We argue that in public health this framework is more suitable, providing an estimate of an action's consequences rather than the less precise notion of a risk factor's causal effect. A variety of modern statistical methods adopt this approach. When an intervention cannot be specified, causal relations can still exist, but how to intervene to change the outcome will be unclear. In application, the often-complex structure of causal processes needs to be acknowledged and appropriate data collected to study them. These newer approaches need to be brought to bear on the increasingly complex public health challenges of our globalized world.

Large nutritional epidemiology studies, with long-term follow-up to assess major clinical end points, coupled with advances in basic science and clinical trials, have led to important improvements in our understanding of nutrition in primary prevention of chronic disease. Although much work remains, sufficient evidence has accrued to provide solid advice on healthy eating. Good data now support the benefits of diets that are rich in plant sources of fats and protein, fish, nuts, whole grains, and fruits and vegetables; that avoid partially hydrogenated fats; and that limit red meat and refined carbohydrates. The simplistic advice to reduce all fat, or all carbohydrates, has not stood the test of science; strong evidence supports the need to consider fat and carbohydrate quality and different protein sources. This article briefly summarizes major findings from recent years bearing on these issues.

Our objective is to provide a current perspective on the avoidable causes of global and US cancer incidence and mortality. Cancer registry–based incidence patterns, population behavioral risk-factor survey data, and systematic reviews of epidemiologic studies are the basis for estimates of relative risk, the prevalence of exposures to various lifestyle and environmental risk factors, and their impact expressed as population attributable fractions (PAFs). Of the total 59 million global deaths in 2008, 12–13% were attributed to cancer. The increasing burden of cancers in low- and middle-income countries (LMICs) is attributable in part to increasing urbanization, expansion of the adult population at risk, and increasing or persistent exposures to infectious agents, tobacco, and dietary deficiencies. Attributable fractions for lifestyle and environmental risk factors are summarized for the United States, the United Kingdom, and France. Assuming minimal overlap in the distribution of risk factors in the population and discounting the potential for interaction in their combined effects, we estimate that a maximum of 60% of cancer deaths in the United States may be attributed to eight risk factors: tobacco, alcohol, ionizing and solar radiations, occupations, infectious agents, obesity, and physical inactivity.

Epidemiological data are reviewed on the prevalence, course, socio-demographic correlates, and societal costs of major depression throughout the world. Major depression is estimated in these surveys to be a commonly occurring disorder. Although estimates of lifetime prevalence and course vary substantially across countries for reasons that could involve both substantive and methodological processes, the cross-national data are clear in documenting meaningful lifetime prevalence with wide variation in age-of-onset and high risk of lifelong chronic-recurrent persistence. A number of sociodemographic correlates of major depression are found consistently across countries, and cross-national data also document associations with numerous adverse outcomes, including difficulties in role transitions (e.g., low education, high teen childbearing, marital disruption, unstable employment), reduced role functioning (e.g., low marital quality, low work performance, low earnings), elevated risk of onset, persistence and severity of a wide range of secondary disorders, and increased risk of early mortality due to physical disorders and suicide.

Substantial population exposure to endocrine disrupting chemicals, combined with available biomarkers and public concern, has resulted in an explosion of human health effects research. At the same time, remarkable shifts in the regulations governing the composition of some consumer products that contain endocrine disruptors (EDs) has occurred. However, important questions remain as to the weight of evidence linking EDs to human health end points. In this review, we critically examine the literature linking ED exposures to child neurodevelopment, focusing in particular on two model exposures to demonstrate issues related to bioaccumulative [e.g., polychlorinated biphenyls (PCBs)] and rapidly metabolized (e.g., phthalates) compounds, respectively. Issues of study design, confounding, and exposure measurement are considered. Given widespread exposure to these compounds, the potential public health consequences of even small effects on human health are substantial. Therefore, advancing our understanding of any impact calls for careful attention to the principles of causal inference.

Energy use is central to human society and provides many health benefits. But each source of energy entails some health risks. This article reviews the health impacts of each major source of energy, focusing on those with major implications for the burden of disease globally. The biggest health impacts accrue to the harvesting and burning of solid fuels, coal and biomass, mainly in the form of occupational health risks and household and general ambient air pollution. Lack of access to clean fuels and electricity in the world's poor households is a particularly serious risk for health. Although energy efficiency brings many benefits, it also entails some health risks, as do renewable energy systems, if not managed carefully. We do not review health impacts of climate change itself, which are due mostly to climate-altering pollutants from energy systems, but do discuss the potential for achieving near-term health cobenefits by reducing certain climate-related emissions.

In the face of growing world human and animal populations and rapid environmental change, the linkages between human, animal, and environmental health are becoming more evident. Because animals and humans have shared risk to health from changing environments, it seems logical to expand the perspective of public health beyond a single species to detect and manage emerging public health threats. Mitigating the effects of climate change, emerging pathogens, toxicant releases, and changes in the built environment requires a retooling of global public health resources and capabilities across multiple species. Furthermore, human and animal health professionals must overcome specific barriers to interprofessional collaboration to implement needed health strategies. This review outlines the relationships between human, animal, and ecosystem health and the public health challenges and opportunities that these links present.

Background: Asbestos-related diseases are still a major public health problem. The World Health Organization (WHO) has estimated that 107,000 people worldwide die each year from mesothelioma, lung cancer, and asbestosis. We review what is known about asbestos use, production, and exposure and asbestos-related diseases in the world today, and we offer predictions for the future. Although worldwide consumption of asbestos has decreased, consumption is increasing in many developing countries. The limited data available suggest that exposures may also be high in developing countries. Mesothelioma is still increasing in most European countries and in Japan but has peaked in the United States and Sweden. Although the epidemic of asbestos-related disease has plateaued or is expected to plateau in most of the developed world, little is known about the epidemic in developing countries. It is obvious that increased asbestos use by these countries will result in an increase in asbestos-related diseases in the future.

This article investigates various ways that transportation policy and planning decisions affect public health and better ways to incorporate public health objectives into transport planning. Conventional planning tends to consider some public health impacts, such as crash risk and pollution emissions measured per vehicle-kilometer, but generally ignores health problems resulting from less active transport (reduced walking and cycling activity) and the additional crashes and pollution caused by increased vehicle mileage. As a result, transport agencies tend to undervalue strategies that increase transport system diversity and reduce vehicle travel. This article identifies various win-win strategies that can help improve public health and other planning objectives.

Implementation science studies the use of strategies to adapt and use evidence-based interventions in targeted settings (e.g., schools, workplaces, health care facilities, public health departments) to sustain improvements to population health. This nascent field of research is in the early stages of developing theories of implementation and evaluating the properties of measures. Stakeholder engagement, effectiveness studies, research synthesis, and mathematical modeling are some of the methods used by implementation scientists to identify strategies to embed evidence-based interventions in clinical and public health programs. However, for implementation science to reach its full potential to improve population health the existing paradigm for how scientists create evidence, prioritize publications, and synthesize research needs to shift toward greater stakeholder input and improved reporting on external validity. This shift will improve the relevance of the research that is produced and provide information that will help guide decision makers in their selection of research-tested interventions.

Adolescent behavior problems such as substance use, antisocial behavior problems, and mental health problems have extremely high social costs and lead to overburdened mental health and juvenile justice systems in the United States and Europe. The prevalence of these problems is substantial, and at-risk youth often present with a combination of concerns. An understanding of risk and protective factors at multiple levels, including the child, family, peer, school, and community, has influenced intervention development. At the individual and family levels, the most effective and cost-effective programs work intensively with youth and their families or use individual and group cognitive-behavioral approaches. However, there is a paucity of careful studies of effective policies and programs in the juvenile justice system. Research is needed that focuses on adoption, financing, implementation, and sustainable use of evidence-based programs in public service systems. In addition, the field needs to understand better for whom current programs are most effective to create the next generation of more effective and efficient programs.

The target for TB elimination is to reduce annual incidence to less than one case per million population by 2050. Meeting that target requires a 1,000-fold reduction in incidence in little more than 35 years. This can be achieved only by combining the effective treatment of active TB—early case detection and high cure rates to interrupt transmission—with methods to prevent new infections and to neutralize existing latent infections. Vigorous implementation of the WHO Stop TB Strategy is needed to achieve the former, facilitated by the effective supply of, and demand for, health services. The latter calls for new technology, including biomarkers of TB risk, diagnostics, drugs, and vaccines. An important milestone en route to elimination will be reached when there is less than 1 TB death per 100,000 population, marking entry into the elimination phase. This landmark can be reached by many countries within 1–2 decades.

The success of public health has been its ability to understand contemporary health problems, to communicate the needs successfully, to identify solutions, and to implement them through programs and policies. In the past 50 years, those successes can be attributed largely to control of infectious disease, improved maternal and child health, delivery of other personal health care services, and changes in behaviors, particularly smoking. Yet health is primarily a product of our social, cultural, and physical environments. To continue to improve the nation's health and reduce disparities, public health needs to return to its historical roots and engage with other sectors to create healthier communities. To do so requires expanding public health skills in areas such as quantitative policy analysis, communication, and community engagement.

Women's vulnerability to HIV infection is influenced by contextual factors in the risk environment that operate at multiple levels (i.e., physical, social, economic, policy). We present three case studies that illustrate combination approaches to HIV prevention among women who are at heightened risk for infection, especially sex workers, in low- and middle-income countries (LMICs). Lessons learned from these case studies are consistent with international literature promoting interventions that combine sexual risk reduction, condom promotion, and improved access to sexually transmitted infection (STI) treatment in the context of structural interventions, including policy change and empowerment of sex workers to reduce their vulnerability to HIV/STIs. We suggest avenues for future research and new intervention targets as well as a more nuanced approach to understanding the structural and social vulnerability of women to HIV infection in these settings.