Environment includes prescription drugs, industrial chemicals, naturally occurring compounds, food and nutrients, physical agents such as heat and radiation, lifestyle choices and substance abuse, and social and economic factors that affect our health.
Individual susceptibility is controlled by our genes, gender and race.
Time refers both to our age and when we might be exposed to an environmental agent. Throughout our life these three elements interact in different ways that affect our health and independence. Of these three elements, only the environment is within our control. Understanding the environmental components of disease is important because environmental risk factors are associated with a wide range of diseases, such as cancer, birth defects, breathing disorders, and infertility.