Bioaccumulation and biomagnification refer to the increasing concentration of pollutants like pesticides, mercury, and other chemicals as they move up the food chain. Bioaccumulation is when an organism absorbs more of a substance than it eliminates, resulting in increasing concentration over time. Biomagnification occurs when concentrations increase at each trophic level, so organisms at the top of food chains face greater exposure. Pollutants like DDT, PCBs, and mercury are especially prone to bioaccumulation and biomagnification due to their persistence and ability to concentrate in fatty tissues. This can negatively impact wildlife and pose risks to human health through consumption of contaminated fish and seafood.