Increase of concentration of non biodegradable pollution at each trophic level .This phenomenon is called biomagnification
Biomagnification, also known as bioamplificationor biological magnification, is the increase in concentration of a substance that occurs in a food chain as a consequence of:Persistence (can't be broken down by environmental processes)Food chain energeticsLow (or nonexistent) rate of internal degradation/excretion of the substance (often due to water-insolubility)
90 percent loss of energy gets lost at each step in a food chain, and when any consumer has to eat far more food than it ultimately stores as body tissue. If the food contains some material which is not metabolized and cannot be excreted (usually fat soluble rather than water soluble) that material will accumulate in the consumer's body. A carnivore eating the first consumer will receive a high dose of the material, which it, in turn will retain and pass on to the next level if eaten.