Each day people are exposed to a wide variety of agents and stressors that have the potential to impact human health and well-being. Environmental health is the study of those environmental factors and how they may contribute to human health and disease. An individual’s environment is one of the most important contributors to one’s overall wellness and quality of life. Environmental factors play a role in at least 85 percent of all human diseases. More importantly, an individual’s environment is the most easily modified aspect of one’s overall health. Understanding the impact of the external environment, how it interacts with biological processes, and what can be done to eliminate or mitigate negative effects provides better protection for human populations from deleterious health outcomes. Traditionally, science has looked at environmental factors by using a risk-based approach. In this model, information on an agent’s potential to cause harm, as depicted by a dose-response relationship for a given adverse effect, is integrated with an individual’s potential to be exposed to that hazard in order to characterize the likelihood and severity of health risk. As we move into a new era of environmental-health research, scientists are thinking about environmental impacts on human health in new ways. It’s no longer as simple as “the dose makes the poison,” where high doses of a chemical are bad and lower doses are not as bad. While there are still many instances of high-concentration exposures to toxic heavy metals, pesticides, or other substances, a new understanding of how low-level exposures contribute to the development of common disorders such as diabetes, developmental delays, and other modern epidemics is changing the traditional paradigm of toxicology. Timing of exposure during fetal and early-childhood development, mixture effects from combined exposures, impacts on genetic and epigenetic gene regulation, and individual human susceptibilities can result in increased disease incidence or severity. Further, these effects are seen not only in exposed individuals, but also in their direct offspring and potentially subsequent generations. The study of environmental health provides opportunities to mitigate or prevent a wide range of human disease and disability from an individual, community, and policy perspective. We can’t change our genes, but we can change our environment, behaviors, and exposures. This article describes the ways we are exposed to stressors in our environment, the primary fields that contribute to our understanding of environmental health, and some emerging issues that require 21st-century approaches to promoting healthy environments and preventing human disease.
The Impact of Nutrition and Environmental Epigenetics on Human Health and Disease
