Final answer:
Biomagnification is the process where toxic substances like DDT, PCBs, and mercury increase in concentration at higher trophic levels, from primary producers to apex consumers, affecting both ecosystems and human health.
Step-by-step explanation:
The phenomenon of biomagnification refers to the increasing concentration of persistent, toxic substances in organisms as one moves up through each trophic level of a food chain, from the primary producers to apex consumers. A classical example of a substance that undergoes biomagnification is the pesticide DDT, which led to the thinning of eggshells in bird species, as documented in Rachel Carson's book Silent Spring. Other substances that exhibit biomagnification include PCBs and heavy metals like mercury, which can have serious impacts on both aquatic ecosystems and human health, influencing dietary recommendations.