Pesticide poisoning
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Synonyms and keywords: Pesticide intoxication; pesticide exposure; insecticide poisoning; insecticide intoxication; insecticide exposure
Overview
Pesticides are chemicals, either naturally occurring or synthetically produced, which may be used to eliminate unwanted plants, animals, or other organisms. They are used extensively in the agriculture industry as well as in the household and can be classified into five categories, namely: insecticides, rodenticides & avicides, fungicides, herbicides, and cross-classified pesticides. While pesticides are meant to be lethal to various unwanted organisms, they are also generally toxic to humans as well. Roughly 7 million people are poisoned by pesticides annually causing more than 350,000 deaths each year, making it a major issue to be considered for emergency physicians.[1] . This article covers the mechanism of toxicity, clinical presentation and diagnosis, and treatment of intoxicated patients for the major pesticides within each category of pesticide.
Historical Perspective
Classification
Pesticides are classified into groups based on their targets. While some texts may discuss anti-bacterial and other anti-microbial agents, article will focus on the five major categories of pesticides. These are as follows:
- Herbicides
- Insecticides
- Rodenticides & Avicides
- Fungicides
- Major Cross-classified Pesticides
Pathophysiology
The mechanism of toxicity of various pesticides which patients may be poisoned with vary considerably between different categories of pesticides and among the agents within each category. This section will be divided into each category and will discuss the mechanisms of toxicity for the most common agents within each category.
Herbicides
Glyphosate
While commercially produced glyphosate herbicides are generally highly toxic, the active ingredient, glyphosate, has been engineered to be relatively non-toxic to humans. Unfortunately, most commercially produced glyphosate herbicides are packaged with surfactants to increase the effectiveness of the product. Polyethoxylated tallow amine (POETA) is one such surfactant, which is understood to be a primary factor in the toxicity of glyphosate herbicides.
POETA has been shown to cause membrane disruption and inhibition of cellular respiration leading to cell necrosis in patients poisoned by glyphosate herbicides.
2,4-Dichlorophenoxyacetic acid
2,4-Dichlorophenoxyacetic acid has been studied and observed to act in a myriad of pathological mechanisms.
2,4-Dichlorophenoxyacetic acid has been shown in animal studies to uncouple the mitochondrial electron transport chain with inhibition of cytochrome c reductase and succinate dehydrogenase resulting in damage to hepatocyte respiration.
It has also been shown to cause damage to cell membranes by means of significant disturbances to the structure of the hydrophobic phospholipid bilayer resulting in echinocyte formation within erythrocytes and disorganization of the Golgi apparatus.
Further dysfunction of mycrotubules and inhibition of synthesis of complex gangliosides has been demonstrated in animal studies.
Finally, it has also been observed to act as a competitive inhibitor for acetylcholine by acting as a false neurotransmitter binding to acetylcholine receptors.
Paraquats and Diquats
Paraquats and diquats corrosive agents that are rapidly and efficiently absorbed through the mucosa when ingested, however they are not able to be absorbed through intact skin. Paraquats and diquats alike are bipyridyl herbicides which generate reactive oxygen species through successive redox reactions culminating in the generation of superoxide and hydroxyl radicals which are able to rapidly damage various tissue cells by means of lipid peroxidation. They are highly toxic to the liver, lungs, kidney and heart. The lungs are particularly vulnerable to paraquats which tend to accumulate within pneumocytes leading to pulmonary fibrosis.
Insecticides
Organophosphates
Carbamates
Pyrathroid Compounds
Organochlorides
Rodenticides & Avicides
Thallium
Coumarins
Calciferol
Chloralose
Sodium Fluoroacetate
Fungicides
Pentachloraphenol
Orgnaomercury Compounds
Organotin Compounds
Thiocarbamates
Cross-classified Pesticides
Chloropicrin
Metal Phosphides
Arsenic
Causes
Differentiating Pesticide poisoning from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies
Case Studies
External Links =
- http://www.cdc.gov/biomonitoring/insecticides_pesticides.html
- http://www.cdc.gov/niosh/topics/pesticides/
- ↑ Robets, Roberts, D. M., & Aaron, C. K. (2007). Management of acute organophosphorus pesticide poisoning. BMJ: British Medical Journal, 334(7594), 629.