The epidemiological transition that has taken place over the last two centuries in industrialized countries has consecrated the reign of chronic diseases (cancers, cardiovascular and neurodegenerative diseases, etc.). Despite the impact of epidemics, these diseases are now the main cause of death in Europe. A great deal of progress has been made in understanding the mechanisms (or proximal causes) of these chronic diseases : these mechanisms involve oxidative stress, chronic inflammation, epigenetics, disruption of signalling pathways, and so on. This pathophysiological research in the tradition of Claude Bernard is central to the development of therapeutics.
In addition, studies into the more distant causes - in relation to the organism and in time - of disease gained in visibility from the 19th century onwards (Villermé, John Snow) and in the 20th century, with the rise of epidemiology and toxicology. These studies constitute the field of environmental health research. In particular, toxicology has helped to demonstrate that many factors outside the body can trigger or contribute to the pathophysiological mechanisms mentioned, and induce oxidative stress or inflammation, for example. These more distant, or environmental, causes of disease, whether physical, chemical, infectious or social in nature, external to the organism and present before the onset of pathology, constitute a lever for preventive action. The epidemiological transition, to which many prevention initiatives have greatly contributed, demonstrates their role in public health, which is less visible than that of therapeutics, but often at a lower cost per life-year saved. In this respect, environmental health research is to prevention what pathophysiology is to therapy.
The beginnings of the epidemiological transition coincide with those of theAnthropocene (an era that can be traced back to the Industrial Revolution, at the end of the 18th century), which saw the proportion of people living in urban areas rise, the number and quantity of compounds in the environment to rise sharply (to more than 23 000 chemical substances currently registered on the European market) and the so-called " lifestyle factors " to change (sedentary lifestyle, smoking, diet, etc.), posing new challenges for the environment.), posing new challenges for prevention. Environmental health research, at a certain level, can be seen as accompanying societal and technical evolutions, and can help to distinguish, among these evolutions, which ones present a danger, or a benefit, for health.