Biomagnification refers to inc in concentration of the toxicants at successive trophic levels.
Organisms at the top of the food chain are at higher risk of damage due to biomagnification.
It affects human as we are at the top of the food chain, so the accumulation of toxic substances like Hg or DDT is high in us, as we eat everything from primary producer/consumer to tertiary consumer in a food chain.
These toxic substances are carcinogenic in nature, harmful to the reproductive system and the immune system.
It can be represented in a diagrammatic way.