Biological magnification, or biomagnification, is the process where a substance, most commonly something toxic like pesticide, increases in concentration in organisms as it moves farther down the food chain. For example, a small fish may ingest some toxic substance. Then when a larger fish eats that fish, the large fish ingests some of the toxic substance as well. This continues and concentration increases and higher members of the food chain eat. Pesticide is one of the most common substances to go through this process.