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Polychlorinated biphenyls in Mexican cereals and their packings.

The content of polychlorinated biphenyls in Mexican cereals and in their packaging materials was determined. All the samples had polychlorinated biphenyls. In all the food samples and in 73% of the packings, the concentrations of polychlorinated biphenyls exceeded the tolerance limits established by the U.S. Food and Drug Administration. A correlation was found between the values for polychlorinated biphenyls in the cereals and those in their packings, therefore, it is concluded that the main source of polychlorinated biphenyls in Mexican cereals is the transference of those present in the recycled paperboard used for the packings.