In toxicology, bioaccumulation is the process of accumulation of chemical substances in living organisms in such a way that they attain higher concentrations than the concentrations in the environment or in foodstuffs. Substances prone to bioaccumulation reaching increased concentrations as it progresses in the trophic level in the food chain. In function of each substance, this buildup can occur from abiotic sources 40, soil, air, water ) or biotic ( other living organisms ). The main routes of introduction of a chemical substance in a living organism are the respiratory and the digestive and the integumentaria.