Abstract
Epidemiology is increasingly coping with problems correlated with exposures which may have small relative risks. In fact, many chronic diseases, as the most recent common diseases all over the world, may have unknown etiology but also potentially related to environmental exposures. Environmental epidemiology considers the effect of environmental factors on health. More exposure with increasing number of potential environmental hazards has changed the initial application of environmental epidemiology. As a consequence, nowadays it is strongly emphasized on some fields such as molecular epidemiology, but some others have discussed about the importance of its population dimension and the reintegration of epidemiology into public health. Environmental epidemiology research, as a very substantial scope of epidemiology, can consider risk assessments, development of standards and other risk management activities. In addition, it could estimate the co- benefits and co-harms of policies designed to reduce global environment changes, including policies implemented in other sectors (e.g. food and water) affecting human health.1 Environmental epidemiology has indeed several unique features that could make these debates very important.