Many factors affect the scope of toxicity . Factors other than toxicants which add to irritation. Injury or irritation get more of the allergen into skin Occlusion enhances absorption. Characteristics of toxicant and exposure-size, concentration, polarity. Factors which affect response to toxicants.
Some people react more or maybe notice irritation more once exposed.
There are several classifications of allergic reaction. The two most common dermally-related allergies are Types IV and I. Remember, all allergic reactions require a sensitization process, even though the sensitization process is described in detail only for delayed type hypersensitivity. This is the most common allergic reaction. Binding of antigen to carrier protein Presentation of antigen by macrophages to T-lymphocyte in skin or lymph node. Formation in lymph node of effector and long-lived memory cells.