During mixing, loading and application of pesticides, the skin is the most likely body surface to come into contact with the product. Many pesticides can be absorbed through the skin into the blood, and can cause toxic effects. The amount of pesticide absorbed through the skin may be enough to produce severe toxic reactions including death.
In addition, pesticides can also injure the skin directly, a process known as cutaneous toxicity. Skin irritation and skin rashes produced by irritating chemical substances are a very noticeable type of chemical toxicity. Skin infections by fungi (ringworm, athlete's foot, etc.), bacteria, or parasites are also very common medical problems and often have the same symptoms as skin irritation caused by chemical exposure. We live in a world filled with substances which can be irritating to our skin, and we use many of these irritating substances every day without great concern, because we have learned how to restrict our exposure.
The skin and the mucous membranes which cover the openings of our bodies to the external environment (such as in the nose and mouth), form protective barriers which keep water inside the body, and keep the outside (filled with bacteria, fungi, dust, dirt, etc.) from coming in. The skin is really an organ of the body, and a large one at that. The skin is much more than just a simple covering, it is multi-layered, and underneath the surface (which is composed of dead cells), are other layers composed of living cells which react to irritants when they get through. When an irritant reaches these sensitive live skin cells, they can only respond in a limited number of ways, the first of which is a general response to any irritating chemical or physical agent (like sunlight); inflammation. Inflammation has four components; redness, pain, heat and swelling. The degree of inflammation is a direct result of the degree of chemical or physical irritation (dose-response). If the damage is great enough to cause cell death, then the response will be much more severe, and can result in areas of the skin becoming "denuded" (loss of the layers, with the deeper layers being exposed to the surface). Because the response of the skin to many different physical and chemical irritants is similar, the causes of skin irritation must usually be diagnosed by a physician who specializes in skin problems (a dermatologist).