PESTICIDES a discussion of the health hazards associated with chemicals used for control of various pests

General Considerations l Substances used to kill unwanted “pests” l Algae-, herb-, insect-, rodent- l Selective toxicities l Resistance of target species l Bioconcentration l Environmental persistence

Rodenticides l Red Squill (extract from “sea onion”) l Sodium fluoroacetate l Thallium salts l Norbormide l Warfarin l Fumigants (MeBr, phosphine, etc.)

Insecticides CHLORINATED HYDROCARBONS l Organic based structure l Chlorine in the base molecule l Unknown toxic action in the insects l Moderate-to-long persistence l Accumulation in fatty tissue l Toxic action on CNS==>tremors==>death l Some are cancer suspects

Alternatives to Insecticides l Other chemicals l Bacterial insecticides l Growth regulators l Sex attractants l Sterile males l Insect-resistant crops l Questioned effectiveness of insecticides

Herbicides l Usually used to kill broad-leaf weeds and/or defoliate l Most work on basis of action on plant hormones (auxins) l Examples: 2,4-D and 2,4,5-T l Highly toxic byproduct: “dioxin” l Toxicities of dioxin