The study of immune dysfunction is called Immuno toxicology. It is due to exposure of an organism to foreign chemical substance identified within a creature that is not usually produced by or estimated to be existent within that organism. Immune dysfunction may effect in the decline of the action of the immune system. Immunotoxic substances, such as chemicals, pesticides, or drugs, can have adversarial effects on the working of the immune system. The well-known effects comprise enlarged susceptibility to infections or tumors as a result of humoral and/or cellular immunity being co-operated (immunosuppression), autoimmune diseases, chronic inflammation, and progress of allergies.