The four stages of the disposition of a toxic compound to evaluate its toxicity are absorption via membranes in a system, the distribution all through the system, the excretion and removal from the system and lastly, the metabolic fate of the chemical. By using these four stages evaluate the toxicity on DDT. I would also like to know how DDT is transported via the cell membranes. Is it passive diffusion, facilitated diffusion, filtration, active transport and so on?