Note: Radioactive particles produced from a terrorist event travel to pastures as fallout. If the fallout contains radioactive iodine, some of it eaten by the cow would be passed into the cow's milk. Consumption of contaminated fresh milk must be controlled during the first few weeks of an emergency. However, products made with contaminated milk, e.g., cheeses and canned milk, which can be stored for several months, may then be consumed safely.
Source: Armed Forces Radiobiology Research Institute.