The Agency has decided to utilize these protective action guides as the basis for monitoring foods sampled under field assignments issued on the subject of radionuclides in imported foods. For foods produced in the United States the protective action guides provide a set of control measures that can be taken to alter the domestic food production process so that contaminated foods do not reach the market place. This document also provides an emergency level of concern above which responsible officials should take appropriate action to remove domestic products from channels of commerce. FDA's monitoring efforts in the U.S. utilize radioactive iodine in milk as the primary indicator of whether or not a public health risk exists. This approach is used for several reasons.
Radioactive iodine is more toxic than many other radionuclides.
Radioactive iodine is expected to occur in greater abundance in fallout from a nuclear reactor accident of this type than other radionuclides. Radioactive iodine appears in milk within 3-4 days of deposition and milk reaches consumer markets faster than most other foods with the potential for contamination from fallout. In addition milk can be the sole source of nutrition for infants which is the most sensitive group to radioactive iodine. Therefore, the monitoring of milk serves as an early warning system for judging the health risk to consumers. If the predicted peak of contamination for milk reaches 15,000 picocuries per liter from I-131, responsible officials should take immediate preventive measures to alter the food production process such as removing cattle from pasture.