A correct answer would explain bioaccumulation of organochlorines in individual organisms. Then it would talk about how concentrations of organochlorines could biomagnify as you went up a food chain. Then you'd need to finish by saying where meat, fish, poultry and dairy are on the food chain, and where we are. Your answer would need to include an explicit statement of why they are the largest contributors of organochlorines to our diets, based on all this reasoning. An assay is a test of the biological activity of a biological or chemical substance.
Epidemiology is the study of diseases in large populations.
Explain the following diagram. The explanation for the diagram can be found in its caption on p. 350 of the Nebel and Wright book. It illustrates the phenomenon of biomagnification.