refers to the accumulation of substances, such as pesticides, or other chemicals in an organism.[1] Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. Thus, the longer the biological half-life of the substance the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high.[2] Bioaccumulation, for example in fish, can be predicted by models.[3] Hypotheses for molecular size cutoff criteria for use as bioaccumulation potential indicators are not supported by data.[4] Biotransformation can strongly modify bioaccumulation of chemicals in an organism.[5]