The immune system plays a central role in the health of the individual. It protects us from disease by recognizing and eliminating or removing foreign material from our bodies. Exposure to a variety of chemicals can effect this system adversely; putting us at risk for illness and disease. Allergy is caused by an oversensitive immune system, which leads to a misdirected immune response. The immune system normally protects the body against harmful substances, such as bacteria and viruses. In contrast, an allergic reaction is when the immune system reacts to substances (allergens) that are generally harmless and in most people do not cause an immune response.