**Preface to "Environmental Exposure to Toxic Chemicals and Human Health"**

It was recently reported that pollution was responsible for 9 million premature deaths in 2015, making it the world's largest environmental risk factor for disease and premature death. Throughout life, people are exposed to both naturally occurring and human-made chemicals. Human health can be influenced by many factors, including exposure to physical, chemical, biological, and radiological contaminants in the environment. These exposures are a root cause of a significant disease burden that could be prevented by reducing or removing chemical exposure. In recent decades, the awareness of toxic chemicals among citizens has been a topic of interest, particularly concerning national and international policy decision makers, expert/scientific platforms, and health protection organizations (WHO, UNEP, CDC, EFSA, IPEN, etc.).

As a complex field, researchers continue to wrestle with important issues, which require an integrative and multidisciplinary research approach to this problem, resorting to complementary methodologies to measure human exposure to environmental chemicals and assess their health effects.

Biomonitoring studies are a good example of this complementarity, encompassing the measurement of internal levels of chemicals/metabolites in easily accessible biological fluids or tissues, which help us to understand environmental health threats and to assist policy measures, namely in susceptible populations.

Preventing diseases arising from chemical environments requires the development of a consistent and rational approach to human biomonitoring as a complementary tool to assist in providing evidence-based public health and environmental measures, confirming the health effects of toxic chemical exposures, and validating regulatory actions and policies.

> **Virg´ınia Cruz Fernandes and Diogo Pestana** *Editors*
