Iodine in Cow's Milk Produced in the USA in 1980-1981 1.

In 378 samples of milk collected from farms and silos outside California, iodine varied from 30 to 3484 μg/kg and averaged 499 μg/kg. In a previously reported study, iodine in 1021 samples of milk collected from farms in California varied from 22 to 4048 μg/kg and averaged 328 μg/kg. Of samples collected outside California, 68.0% were below 500 μg/kg; of samples collected in California 83.4% were below. Volume weighted averages were calculated for both sets of samples. The volume weighted average outside California was 438 μg/kg and inside California was 316 μg/kg. While some farms do produce milk containing high (more than 500 μg/kg) concentrations of iodine, dilution of that milk with milk lower in iodine results in finished fluid and manufactured products low in iodine; thus it is unlikely that any population group purchasing processed dairy foods at the retail level in the USA will be exposed to excessive concentrations of iodine in the dairy products they consume. However, it is possible that some farm families using only the milk produced on their farms might be at risk.