At a cotton gin in the San Joaquin Valley, in California, a boxy machine helps to spray a fine mist containing billions of molecules of DNA onto freshly cleaned Pima cotton.
That DNA will act as a kind of minuscule bar code, nestling amid the puffy fibers as they are shuttled to factories in India. There, the cotton will be spun into yarn and woven into bedsheets, before landing on the shelves of Costco stores in the United States. At any time, Costco can test for the DNA’s presence to ensure that its American-grown cotton hasn’t been replaced with cheaper materials — like cotton from the Xinjiang region of China, which is banned in the United States because of its ties to forced labor.
