What Dose Makes the Poison? Where Expert Cannot Say, Eleventh Circuit Affirms Summary Judgment

A central tenet of toxicology is that “the dose makes the poison.” Every chemical is toxic if enough of it is consumed, and every chemical has some dose – even if miniscule – at which it poses no significant risk. A chemical must be given in sufficient amount – something exceeding the “threshold dose” – before it will cause effects. This has obvious implications for toxic tort litigation, where a plaintiff who alleges injury from exposure to a toxic chemical must prove at minimum that he or she was exposed to enough of the chemical to produce the alleged injury. This poses a problem for plaintiffs who have been exposed only to very small doses of the chemical at issue. What is a plaintiff to do when their exposure falls below the threshold dose? One approach that generally does not work is to reject the very concept of a threshold dose altogether.