The toxicity of chemicals are determined by their LD50 value. LD50 is an abbreviation for the Lethal Dose 50% or median lethal dose. It indicates the amount of substance required to kill 50% of the test population. It is measured by milligrams of chemical to kilograms of body weight.
The smaller the LD50 value, the more toxic the chemical.
Two commonly used synthetic pyrethroids are Deltamethrin and Bifenthrin. Deltamethrin is used for quarantine in the export of wild flowers from WA and Tas. And Bifenthrin is registered for use on apples, bananas, carnations, cotton and roses.