Bioaccumulation is the gradual accumulation of drugs, like pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost by catabolism and excretion. Thus, the longer the biological half-life of a toxic substance, the greater the danger of chronic poisoning, albeit environmental levels of the toxin isn't very high. Bioaccumulation, for instance in fish, is often predicted by models. Hypotheses for molecular size cutoff criteria to be used as bioaccumulation potential indicators aren't supported by data. Biotransformation can strongly modify the bioaccumulation of chemicals in an organism.
