Are humans really at the top? Yes. We are the top of the food chain (unless we are eaten by a shark!), but is it always beneficial to be at the top of the food chain?
Usually food chemicals that we eat are used by our bodies and any waste is exhaled, defecated and urinated out of us. However, some chemicals such as heavy metals like lead and mercury can't be expelled from plants and animals so they build up in the plant and animal bodies. This is called
biomagnification (biological magnification) because the amounts can accumulate more and more in animals further along the food chain till they reach a toxic level.
In human-made environments, radio-active chemicals such as uranium are a problem because the time they take to break down (half-life) can be thousands of years.
