It is known that the effect of biological magnification increases with higher trophic levels. Since, we are at the top of the food chain, how much are we affected by it? Is there any proof of humans affected by biomagnification? And should we be worried?
Thank you, for your attention!
Edit: Before posting here I had searched on Google Scholar about 'effect of biological magnification on humans'. Not only I couldn't find anything specifically about humans, whatever I found were too complex for me to comprehend. (I'm not a student of Biology). Yet, some of those which I understood stated that, accumulation of substances upto hazardous levels poses health risk. What I am trying to know is that, have there been cases where we know biomagnification to have hurt humans?
Biomagnification is the process by which chemical contaminants increase at a far greater rate than thermodynamics would predict. Specifically looking at organic / lipid soluble compounds. A very basic explanation is that as food is digested and the lipids are absorbed, chemical concentration (see Fugacity) within the food increases as it travels along the gastro-intestinal tract. As we consume more of the contaminated food it accumulates in our bodies, and if a threshold is passed can result in negative physical effects in our bodies.
Have humans been affected?
Agent Orange - the US sprayed a significant amount of Vietnam with agent Orange, which contained dioxin. The persistent nature of the compound caused it to accumulate in the soil and vegetation, and eventually the contaminated vegetation was either consumed directly by the people, or by wildlife which in turn, could be eaten. The result was that even though the compound itself was relatively harmless to humans, as it travelled up the food web, the concentration increased via the mechanism described above. The same mechanism is what resulted in pesticides like DDT being banned in the 1970’s.
Should we be worried? (Opinion)
Of course it is something that we should be aware of, and there are some guidelines with eating seafood / fish. Aquatic and marine systems typically can support a higher number of trophic levels and as such we should pay much more attention to seafood. For example, around where I live we have Fish Consumption Guidelines ) that encourage people to limit the number of fish meals per month, especially for women who are or planning to get pregnant. This allows time for our bodies to remove the accumulating compounds before reaching dangerous levels. Therefore, you do not need to eliminate higher trophic organisms from your diet, just enjoy them in moderation and not excess. Knowing where your food comes from also helps in making these decisions.