Immunotoxicity of Pesticides

Publisher Summary This chapter appraises the reaction of the human immune system when it is exposed to different types of pesticides. Chemicals such as pesticides have the potential to alter the immune system, making an individual more susceptible to infection. There are four potential outcomes to pesticide exposure. The first outcome, and the most common, is no alteration to the immune system as a result of pesticide exposure. The second potential outcome is an increase in activation of the immune system with the potential to develop into an autoimmune disease. A third possible outcome of pesticide exposure is a decrease in the immune system activity resulting in immunosuppression. The final potential outcome is the development of hypersensitivity. Depending on the pesticide, these alterations can include a decrease in neutrophil and macrophage function, a decrease in the number of thymocytes, a decrease/increase in mitogen-induced proliferation, a decrease in antibody-dependent cell cytotoxicity, and a decrease/increase in cytokine secretion. As in other types of pesticide-induced toxicities, the route of exposure, length of exposure, dose, and timing of exposure of a pesticide must be taken into consideration when evaluating the potential of a pesticide to be immunotoxic. In addition, these factors can also influence whether a pesticide is immunosuppressive or potentiates the immune system.