High-End California Cotton Stays Pure Thanks to DNA Testing

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California Pima cotton, said to be some of the world's finest. (Ezra David Romero/KQED)

Kirk Gilkey is a farmer in Kings County, where drought and higher-priced crops are hurting California's cotton industry. Acreage has dropped from over 600,000 10 years ago to well under 200,000 today. Gilkey grows Pima cotton. He kept the crop because of its high price point.

"It's given us our only chance over the years," Gilkey says. "If I wasn’t growing Pima, I wouldn’t be in the cotton business anymore."

He says the higher price is enough to offset the costs of water and the lure of other crops.

After Gilkey's cotton is harvested, it’s packed into huge rectangles that look like giant sticks of butter from the roadside. It’s then trucked to his gin, where a pipe sucks the cotton from outside into the factory. A series of ceiling-high machines, dryers and saws rid the cotton of sticks, dirt and seeds.

But before the fluffy white cotton is compacted into 500-pound bales, a new step in the process was added last year at his gin. The cotton is sprayed with a DNA serum in the form of fog.


“That binds permanently to the cotton fiber,” says Jim Hayward, who leads Applied DNA Sciences, the company behind the product. “That allows us to track it to a point of origin to say this comes from the San Joaquin Valley.”

The DNA serum step was added because Hayward’s company led an independent study on cotton textiles. It found that sheets labeled "100 percent Pima" sold at popular American retailers had been cut with subpar fiber.

One of those retailers called up David Greenstein, CEO of the major textile producer Himatsingka, which sells Pima cotton sheets to retailers like Costco.

"The customer called me and said: Do you know that this product that you’re supplying us is not 100 percent pure?” Greenstein says. “We were unaware. We thought we were innocent, so we said that can’t be."

Greenstein oversees the supply chain that takes cotton to China where it’s spun into thread, to India where it’s made into fabric and then to American stores like Costco. Greenstein called Hayward, the scientist behind the DNA technology, and asked him for help. They came up with a way to test cotton fabric for the exact types of fiber in it.

“And then we started to understand how this DNA fiber typing works, and then we realized it was true,” says Greenstein.

He immediately knew where the problem was in his supply chain: Chinese spinners. They turn cotton into thread. So he hopped on a plane to China with a delegation of farmers, scientists and retailers to confront the company that was selling him the bogus thread.

Greenstein made a presentation to the Chinese spinners, outlining his evidence.

"They asked for time, and they left us in the room and went to talk among themselves, and they came back and told us they were ready to admit to certain things."

Prof. Lizhu Davis says DNA tagging technology could change the way supply chains are monitored in the textile industry.
Professor Lizhu Davis says DNA tagging technology could change the way supply chains are monitored in the textile industry. (Ezra David Romero/KQED)

Those things included mixing in cheap-quality cotton with more expensive types, like Pima.

Instead of firing them, Greenstein decided to continue using the spinners now that he could basically proof their work.

Now a handful of other California growers tag their cotton with the DNA serum, and Greenstein's company is using that cotton to make sheets under the brand PimaCott. Currently, PimaCott bedding can be bought only at Costco.

I brought a sample of the sheets to someone who knows a lot about fabric. Lizhu Davis manages a fashion merchandising program at Cal State Fresno.

“Wow, it’s very luxurious,” Davis says. “Feels just like silk.”

Davis hopes that this use of DNA technology to track products globally is just the beginning of a change in her industry. She suspects the DNA tagging system could also be used on silk and synthetic materials.