Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. 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. when a dangerous substance finds its way into the environment and it finds a body of water then the water is contaminated and all of the fish swimming and living in that water also become contaminated. then other animals eat the fish including us humans and we also eat those other animals. So the more toxins we are putting in the environment the more it builds up in the food web and the more organisms become contaminated.

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