Environmental risk transition is the process by which traditional communities with associated environmental health issues become more economically developed and experience new health issues. In traditional or economically undeveloped regions, humans often suffer and die from infectious diseases or of malnutrition due to poor food, water, and air quality. As economic development occurs, these environmental issues are reduced or solved, and others begin to arise. There is a shift in the character of these environmental changes, and as a result, a shift in causes of death and disease.
Risk transition framework
Several transition frameworks have been established to better understand the impacts of socioeconomic development. Of these, the oldest and most well-known framework is the Demographic transition framework, which was established in the 1940s. This describes the shift from high fertility and high mortality in underdeveloped societies to lower fertility and mortality rates as a result of development. Then around 1970, the Epidemiological transition framework was used to characterize changes in the health of societies during development. To better categorize causes of death and disease when studying the epidemiological shifts more well-defined categories were created to describe illnesses and injuries:
I. Traditional, infectious, nutritional, perinatal, and maternal causes
II. Modern, cancer, heart, neuro-psychiatric, chronic lung, diabetes, and congenital causes III. Non-transitional injuries, both unintentional and intentional
In 1990, environmental health researcher Kirk R. Smith at the University of California, Berkeley proposed the "risk transition" framework in relation to the established demographic and epidemiological transition frameworks. This theory was based on the concept that there must be a shift in risk factors leading up to a shift in causes of death and disease. In efforts to prevent, rather than respond to diseases, the risk transition was further studied and quantified. Figure 1 shows the relationship between risk, epidemiological, and demographic transition, in which risk factors change to affect patterns of disease and health, which in turn affects the demographic. However, a shift in population also impacts the risk factors, and so these three frameworks all show significant impact on one another.
The "environmental risk transition" framework further developed by Smith then more specifically categorizes the risks as traditional and modern as well as spatially. Based on the framework, during the first stages of development, environmental health issues concentrated in the household, such as poor sanitation, are resolved by shifting them into the community, causing issues such urban pollution. This can be labeled as traditional and modern risks, respectively. Then, upon further development, these risks in the community are decreased and shifted to the global environment, creating concern for changes such as heightened greenhouse gas emissions, etc. Modern risks, in contrast to traditional risks, tend to be accrued over time in which adverse effects do not have single identifiable causes. These categorizations were made since it was found that the majority of environmental risks associated with category I diseases presented itself in the household, and as these were resolved with development, the impact of environmental causes of category II diseases became more significant and emerged at the community level. This concept is illustrated in Figure 2.
Quantifying
Utilizing data from the Global Burden of Disease Study (GBD) and the Comparative Risk Assessment (CRA) managed by the World Health Organization (WHO), empirical data was gathered to test the environmental risk transition framework.
Measuring development
Well established metrics of quantifying development in a society include income per capita adjusted for local purchasing power in 2000. This is termed dollars of gross domestic product/capita, adjusted for purchasing power ($PPP/capita). Similarly, the Human Development Index (HDO), utilizes a combination of purchasing power income per capita, life expectancy, and education level in 2000 to measure development in a population.
Risk metric
To understand the effects of environmental risks internationally, a per capita measure of a risk factor's impact is more useful, so risks were quantified in percent of total disease burden measured in % Disability-adjusted life years (DALYs) and burden per capita (DALYs per 1000 capita).