Bioassay- measurement of the potency of a substance by its effect on living cells. Toxicant- any substance that can cause a toxic effect. Xenobiotic- relating to or denoting a substance, typically a synthetic chemical that is foreign to the body or to an ecological system. Target organism- the unwanted pests you intend to kill. Therapeutic index- comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes death or toxicity. Fundamental laws of toxicity: no toxicity without exposure, dose makes the poison non-toxic, slightly toxic, very toxic. Hormesis- opposite effect in low doses as in high doses (threshold) Partition constant- ration of concentrations of a compound in a mixture of 2 immiscible phases at equilibrium ie. measure of the difference in solubility of the compound in these 2 phases. Kow- octanol and water partition constant; octanol has same c:o as most lipids; if 5000 likely to bioconcentrate.