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ACUTE TOXICITY OP PESTICIDES http://orchard.uvm.edu/uvmapple/pest/9697neapmvtxcq•.html npPl.r.� •11n+¢rmret .aik IX 1996-1997 New England Apple Pest Management Guide ACUTE TOXICITY OF PESTICIDES Pesticide hazard to warm-blooded animals, including humans, is usually determined in relation to the way it enters the body. Methods of entry include the respiratory system, digestive system and skin. The greatest hazard is by pesticide entry via the respiratory system. Pesticide toxicity by this route is not much different from that of intravenous injection because membranes of the lungs that separate air from blood are extremely thin; therefore absorption is very rapid (this is also true for the eyes). Absorption through the digestive tract is the next most hazardous avenue for poisoning. The skin provides the most effective barrier against pesticides. However, there is considerable variation in the rate of penetration through the skin by different materials and formulations. The greatest hazard from pesticides occurs while mixing and applying, not from accidental ingestion. However, when spraying, many airborne spray particles are trapped in the secretions of the upper respiratory tract and swallowed, thereby providing exposure by ingestion. Assuming that the person applying the pesticide takes adequate precaution (respirator, goggles, etc.) to prevent this type of exposure, dermal toxicity is probably a more realistic index of occupational hazard than oral toxicity. DANGER-POISON, WARNING, CAUTION: One of these "signal words" appears on the label of every pesticide. Acute (or immediate, single dose) toxicity is reported as an LD50 value. See Table 8 for Acute Toxicity Ratings of some apple pesticides. The LD50 for a chemical is the dose which has been found in controlled experiments to kill 50% of a large number of test animals. The LD50 dose is usually expressed as the number of milligrams (mg) of pure active ingredient per kilogram(kg) body weight of the test animals. The lower the LD50, the more toxic the chemical. Because the LD50 is based on animal tests and does not account for individual sensitivity, it does not necessarily represent the toxic dose for an individual human. The LD50 of a chemical gives no information on the possible long term health effects from repeated exposure at low levels. In addition to oral or dermal acute toxicity, a pesticide may also carry the DANGER-POISON, or WARNING signal words because of other potential hazards, such as inhalation toxicity or the ability to cause severe eye or skin damage. Table 9. Acute Toxicity of Apple Pesticides. LD50 for test animals LD50 for test animals i (mg technical (mg technical chemical chemical per kg body weight) per kg body weight) Oral [Dermal Oral Dermal Chemical Oral – — I of 5/15/00 10:50 AM