Learn More About Pesticides

Classes of Pesticides

fruites and vegetablesThe term pesticide is a very broad term that covers a large number of more accurate names of pesticides based on usage. Pesticides are economically justifiable poisons needed for both public health (e.g., malaria prevention) and crop production as the human population continues to grow. In residential scenarios, pesticides can improve quality of life, help maintain infrastructure, and improve the aesthetic appeal of property. However, all pesticides must be used according to label instructions and relative toxicity of pesticides can vary widely, meaning education and responsible application must always be used or potential adverse effects increases in non-target species.

There are 5 major classes of pesticides:

  1. Herbicides: used to mitigate nuisance plant species (example: atrazine, 2,4-D)
  2. Insecticides: used to mitigate nuisance insect species (example: malathion)
  3. Fungicides: used to mitigate nuisance fungal species (example: azoxystrobin)
  4. Biocides: used to mitigate nuisance viral, bacterial, and protozoan species (example: disinfectants)
  5. Rodenticides: used to mitigate nuisance rodent species (example: warfarin)

The development and diversity of pesticides has increased over the decades and now there are also other classifications of pesticides used such as fumigants, molluscicides, nematocides, etc. that also act on a particular species (e.g., molluscs, nematodes respectively) or are used in gas or vapor form (i.e., fumigants).

Of the pesticide classes listed, insecticides pose the greatest risk to mammals and overall ecological health as some - such as organophosphate pesticides - are non-target specific, similar in chemical structure, and therefore have a similar mode of action on an acute basis (i.e., neurotoxicity) on numerous organisms.

Some insecticides are more target-specific (e.g., BTI), and induce a range of effects (e.g., growth inhibition, interference with molting) increasing safety to non-target organisms. There are several classes of insecticides including:

  • Organochlorines (OCs) (examples: DDT, endosulfan)
  • Organophosphates (OPs) (examples: malathion, diazinon)
  • Carbamates (examples: carbaryl, aldicarb)
  • Pyrethrins and Pyrethroids (example: permethrin)
  • Insect Growth Regulators (IGR) (example: methoprene)
    Ballantyne B, Marrs TC, Syversen T. (eds.). 1999. General and Applied Toxicology, 2nd Edition. John Wiley and Sons, Inc. New York, NY.

The decision-making tool's relative cumulative evaluation for all pesticides is based on acute and chronic toxicity values (i.e., hazard data) and physical and chemical properties (i.e., environmental fate and transport characteristics) of pesticides and is derived from the U.S. EPA data in an effort to maintain consistency in comparing the compounds as well as follow the structure of the current U.S. regulatory framework.

For More Information:

USEPA's Pesticide Page

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