Contamination of Gluten-Free Foods
At this point, companies can say their products are gluten-free even if they contain significant amounts of gluten due to contamination in processing. Gluten-free labeling is currently unregulated in the United States (although final labeling standards are expected soon). No federal labeling standard exists for gluten.
This means that gluten-free doesn’t necessarily mean that a food product is fully free of gluten. The fact is that even naturally gluten-free foods can pick up trace amounts of gluten in processing and manufacturing.
Some companies use the same equipment to manufacture or package several different products. For example, a potato chip company may run chips with gluten-containing flavorings on the same conveyor belts as plain potato chips, causing the plain ones to be contaminated with gluten.
Laws require cleaning between runs, and many companies run gluten-containing products on different days from gluten-free products. They clean equipment well between runs and observe other safe practices.
Still, some people choose to eat only gluten-free foods that have been produced on totally separate lines or separate facilities altogether if gluten makes them severely sick — just to be on the safe side. You can call specific companies to confirm the processes used to manufacture and package the foods you question.
The Food and Drug Administration (FDA) has proposed that when gluten-free labeling requirements are implemented, only foods that test less than 20 parts of gluten per million will be able to claim to be gluten-free. According to most celiac experts, that trace amount is safe for people who must avoid gluten altogether, even after several servings throughout a day.