Ingestion was a surprise that shouldn't have been. Along with iodine, milk and greens both concentrate strontium-90 and a couple of others. That they were tracing I-131 exposure to milk, and not so much Sr-90 was the surprise to me, because Sr-90 in milk is a text book issue due to the Sr's love of Ca. Standard precautions against exposure to fallout, along with decontamination and runoff containment, were not as well followed as they should have been. At least not according to what I've read.