ABSTRACT
When the effects of a toxicant are less obvious than death, assessment of its toxicity is
guaranteed to be a contentious enterprise. The notion that toxins could produce important
health outcomes short of fatality was slow to develop and only recently accepted. The
discipline of toxicology, after all, began as an offspring of the widespread clandestine
practice of poisoning one’s rivals. One of its more prominent exponents was Nero’s
mother, Agrippina. It is only recently that toxicologists abandoned as the main metric of
potency the LD50, the dose that killed half of one’s experimental animals. At about the
same time, case reports of lethal exposures in humans became rare, and were replaced with
epidemiological investigations of toxicity at doses below the fatal.
