Environmental pollutants such as PCB's contaminate oceans and other aquatic systems. Plankton in the ocean become contaminated by PCB's and pass this along through the food chain. A pregnant woman has been cautioned to limit her consumption of food that may be high in PCBs. If she consumes food from a nearby contaminated ocean, we would expect that the most contaminated foods would be a shrimp that eats plankton. b fish that eat shrimp. c kelp and other ocean plants. d clams that filter and eat plankton.

The food chain is constructed from complex food web and demonstrates how food connects organisms according to their consumption and each level discuss different tropic level. As every food chain starts from producer organisms and ends by top predators. Here, toxic chemical released from industrial activities like PCB (polychlorinated biphenyls) which are insoluble in water.

Therefore, sink to the bottom and link with sediments and consumed by small organism like plankton, while shrimps consumes plankton and small fish consumes shrimps, bigger fish consumes smaller fish and contain huge amount of PCBs therefore finally these fishes are consumed by apex predators like humans or whale. Therefore, a pregnant woman is being cautioned in limiting her consumption of food that might be high in PCBs.