Description of Major Groups of Chemical Pesticides

Class of Chemical First Used Examples Types Current Status Effects Pesticides

Organochlorines 1942 aldrin; chlordane; dieldrin; insecticide, Lindane, methoxychlor and Persistent, bioaccumulative, endrin; heptachlor; lindane; acaricide, pentachlorophenol are registered affect the ability to reproduce, methoxychlor; toxaphene; HCB & PCP in Canada. The other products develop, and to withstand hexachlorobenzene (HCB); are fungicides have been discontinued in environmental stress by pentachlorophenol (PCP); Canada, but they are still used in depressing the nervous, DDT developing nations endocrine and immune systems Organophosphates Very early schradan; parathion; insecticide, Schradan was discontinued in Non-persistent, systemic 1940s malathion acaricide 1964 and resulted in a move (cholinesterase-inhibiting), not toward less toxic groups (e.g. very selective, toxic to human malathion, parathion) Carbamates First appeared carbaryl; methomyl; propoxur; fungicide, Aldicarb was discontinued in Non-persistent, cholinesterase- in 1930 but aldicarb insecticide, 1964; the others are registered inhibiting, not very selective, large-scale acaricide in Canada toxic to birds and fish use in mid- 1950s Although carbamates share a mode of action with the organophosphates, their effects are reversible and they are biotransformed in-vivo Phenoxy Large-scale 2,4-D herbicide 2,4-D is widely used Selective effects on humans marketing and 2,4,5-T and mammals are not well distribution 2,4,5-T banned in Canada known began in 1946 2,4-D: potential to cause cancer in laboratory animals

2,4,5-T: is the source of a toxic contaminant dioxin Pyrethroids 1980 fenpropanthrin; deltamethrin; insecticide Fenpropanthrin is not registered Target-specific: more selective cypermethrin in Canada, unlike the two other than the organophosphates or pesticides carbamates, generally not acutely toxic to birds or mammals but particularly toxic to aquatic species