Environmental Risk on Health. The UN Millenium Objectives for Development (MOD), adopted in 2000, consider that human health is the main condition of human and economic development, engaging all governments to improve health by preventing environmental decay, since lack of access to essential environmental resources (clean water supply; basic sanitation facilities; proper outdoor and indoor environment), exposure to physical, chemical and biological hazards in the environment (air and water pollution) and global environmental changes due to major climatic changes represent actual risks on human health. The environmental risk assessment comprises four distinct and essential components: hazard identification; exposure assessment; assessment of dose-response relationship and risk characterization, which ultimately lead to the identification of risk nature, importance and range. This assessment is very useful in mortality and morbidity charge studies, which reveal that environmental risk factors play an important role in health degradation.