1. Social and Environmental Determinants of Population Health
Social and environmental conditions shape patterns of population health across the world. While diseases are influenced by a number of specific risk factors and agents, socioeconomically disadvantaged men and women and those who are socially excluded from full participation in their societies are almost without exception at increased risk for whatever diseases are prevalent in their society. Thus, while specific disease agents and risk factors come and go, the social and physical environment shapes both the distribution of risks as well as susceptibility and resilience to risk. Identification of these environmental conditions in both industrialized and developing countries and understanding the ways in which they become biologically embedded is a central aim of this theme. Poverty, economic inequality, social isolation and exclusion and job stress along with environmental conditions related to pollution, unsanitary living conditions and poor nutrition shape health in ways that the health care system will be hard pressed to fix. The recent WHO Commission on the Social Determinants of Disease illustrates both the scientific as well as practical significance of reducing health disparities through social and environmental changes. The Harvard Population Center is fortunate to have a number of epidemiologists and economists as well as physicians and other social scientists who can work together to explore issues that are often bound by distinct disciplinary approaches. In an area in which scientists often contest the methods and results of scientists in other fields, we are very fortunate to have a long history of collaboration across disciplines. For instance, epidemiologists and economists have often used different methods to explore similar issues and have different approaches to understanding causal inference. Our aim is to bring together faculty from these disciplines to engage in conversation about how to take the best and strongest methods and approaches to understanding causal processes.
2. Causes and Consequences of Health and Demographic Transitions
Human welfare is directly associated with health and demographic transitions. Mortality decline in the late 19th and 20th centuries, itself representing a huge gain in welfare, resulted in sharp increases in population growth rates and sharply younger populations, especially in the now developing world. The rapid fertility declines that followed, first in the now developed world but from the 1960s onward increasingly in the developing world as well, sharply reduced growth rates leading to rapidly aging populations. These changes in population size, dependency ratios and relative cohort sizes have had - and continue to have - dramatic effects on population distribution, living conditions, family structures, fiscal balances, and a whole host of other factors key to human welfare, including on the determinants of population change themselves. These dynamics will continue unabated in the future with consequences that will no doubt include both the expected and the unexpected. Good policy will require good evidence of likely causal connections, good monitoring of what is actually happening, and sound methodologies. HCPDS researchers are making important contributions in these areas.
3. Population Mobility: Migration in a Global Economy
Migration is a complex global phenomenon that has grown rapidly in recent decades. Estimates of the global total of international migrants rose from 75 million in 1965 to 120 million in 1990 and 175 million in 2000. The United States towers above all other countries in the number of immigrants received (35 million), followed by the Russian Federation (13.3 million), and Germany (7.3 million). The period since 1960 has witnessed a sharp growth of immigration to the US, Canada and Australia, as well as to the countries of Western Europe. These countries have all experienced a growth in the second generation-the children of the earlier immigrants, as well as continued flows of immigrants and refugees. Internal migration in China and India dwarfs these numbers with the current movement in China from the countryside to the city of 80-120 million people, described as the largest movement of people in human history.
These large migration flows and the resulting integration challenges have led to a great deal of research on immigrant identities, on transnational connections between sending and receiving societies, and on patterns of social, cultural and economic integration. In an interdependent world of growing geographic mobility, increasing regional integration, and fast and cheap communication migration is a field with tremendous demographic significance. Yet most research on immigrant and second generation integration has been conducted within a single nation state (with the vast majority done in the United States), with little comparative analysis. And much immigration research assumes a conventional view of migrants moving to a new country permanently and slowly adopting the culture of this new environment. This does not capture the reality of many immigration flows today. Many new immigrants are "transnationals" and truly live in two worlds - their country of origin and their new country. Many migrants move from the countryside to the city but do not cross international borders, while other highly skilled migrants in places like the European Union do cross internation borders but notice very little differences in their cosmopolitan lifestyles.
Critical will be the study of immigrant integration and identity in both the United States and other immigrant receiving societies in Western Europe and to facilitate comparisons of these processes that advance our theoretical and public policy understandings of these phenomena. This includes systematic comparisons of integration across different societies and examinations of similarities and differences between internal migration within developing countries such as China and India, and international migration from less developed nations to more developed countries.
4. Health Consequences of Labor Policies and Work Design
Traditional occupational health research focuses on the identification of physical and toxic exposures in the work place. Some estimates suggest that between 1933 and 1997, unintentional work related accidents and injuries were reduced by almost 90 percent as a result of occupational health and safety regulations. It is likely that today a number of labor protection policies - workers compensation, unemployment, minimum wage - also have an impact on health outcomes through entirely different mechanisms and pathways. We rarely study those policies and the impacts they may have on health. In addition, scientists have identified key aspects of the work environment that have to do with its social organization that have major impacts on health and well being. Job control and job demands for instance have been linked to cardiovascular risk and sickness absence in a number of studies. Job insecurity has recently been reported to have an impact on health in several countries. The evidence on job loss and retirement has been more controversial with some studies showing health risks and some showing null results. We suspect that other work conditions particularly those related to flexibility and work family balance will play an increasingly important role in shaping the health of the workforce and their families in coming decades. These workplace policies may be of particular importance to women, low and middle wage earners, immigrants and older workers. A central aim of the researchers working in this area will be to study the health impact of these social and economic work place policies.