Iowa Code § 194.9: Unlawful milk.

Milk, which from the standpoint of organoleptic examination is not acceptable, or which contains excessive extraneous matter or which by three out of five bacterial estimate tests is classified in excess of three hundred thousand, or which contains material evidencing production from a mastitic cow, or which contains chemicals, medicines, or radioactive agents deleterious to health, is unlawful for the manufacture of dairy products for human consumption.