This book brings together articles on the overarching theme of how the environment shapes the immune system.

The immune system is commonly assumed to respond to harmful pathogens such as bacteria and viruses. However, harmless bacteria, chemicals, stress, normal food and other factors can also trigger, shape or interfere with the immune system, often producing adverse effects. Yet, it is also becoming increasingly accepted that some of these interactions are physiological and necessary for a healthy immune system.

Examples of negative effects include the immunosuppressive effects of UV irradiation, or the immunotoxic effects of man-made chemicals such as ... Read morepolycyclic aromatic hydrocarbons. Autoimmunity or allergies can be the adverse consequences of interaction between the immune system and chemical compounds such as drugs. Positive effects can come from natural exposure levels to bacteria, healthy life-style or the diet.