Pesticides, or insecticides, are chemicals used to control infestation in a garden, farm or living area. According to Penn State University, these chemicals must be biologically active, or toxic, to affect the pests. Although targeted toward insects, insecticides may have many other undesirable effects.
Acute toxicity is applied to insecticides which, with one exposure, can cause injury to a person or animal. This may cause either long-term or short-term effects. According to Penn State University, there are four routes of insecticide exposure: dermal (skin), inhalation (lungs), oral (mouth) and the eyes. Acute toxicity is measured according to the absorptive qualities of the chemical in one of the four entry points. Acute effects will usually appear within the first 24 hours of exposure. If treated, the effect will likely be reversible, although if not treated, acute effects may lead to serious neurological breakdown and potentially death.
According to the University of Missouri, some people will develop an allergic reaction to a pesticide soon after exposure. This is called sensitization. Asthma, skin, eye and nose irritation are all potential allergic effects. Some people are more susceptible than others to allergic reactions, while others develop allergic reactions during prolonged exposure. These may be categorized as delayed effects.
Chronic effects, according to the University of Missouri Extension, are classified as those effects that persist over long periods or do not appear until several years after exposure to the chemical. Reproductive damage, tumors, cancer and changes to the body's chromosomes are some of the potential dangers and symptoms of delayed effects. These will not appear until at least 24 hours after exposure and are hard to treat if the person exposed to the insecticide was unaware of exposure.