60 likes | 231 Views
PESTICIDES. a discussion of the health hazards associated with chemicals used for control of various pests. General Considerations. Substances used to kill unwanted “pests” Algae-, herb-, insect-, rodent- Selective toxicities Resistance of target species Bioconcentration
E N D
PESTICIDES a discussion of the health hazards associated with chemicals used for control of various pests
General Considerations • Substances used to kill unwanted “pests” • Algae-, herb-, insect-, rodent- • Selective toxicities • Resistance of target species • Bioconcentration • Environmental persistence
Red Squill (extract from “sea onion”) Sodium fluoroacetate Thallium salts Norbormide Warfarin Fumigants (MeBr, phosphine, etc.) Rodenticides
Insecticides CHLORINATED HYDROCARBONS • Organic based structure • Chlorine in the base molecule • Unknown toxic action in the insects • Moderate-to-long persistence • Accumulation in fatty tissue • Toxic action on CNS==>tremors==>death • Some are cancer suspects
Alternatives to Insecticides • Other chemicals • Bacterial insecticides • Growth regulators • Sex attractants • Sterile males • Insect-resistant crops • Questioned effectiveness of insecticides
Herbicides • Usually used to kill broad-leaf weeds and/or defoliate • Most work on basis of action on plant hormones (auxins) • Examples: 2,4-D and 2,4,5-T • Highly toxic byproduct: “dioxin” • Toxicities of dioxin