Boba milk tea, also known as pearl milk tea or bubble milk tea, is a cold, sugary drink that usually contains little black balls of starch called tapioca. I admit: It is the drink I go to every time the weather is hot. Originally from Asia, it has become one of the most popular beverages among college-age students in the U.S. Teens and kids seem to love it as well. And why not? These little balls of starch, extracted from cassava plants, have a chewy texture and they taste sweet, but not overwhelming so.
Last fall, a report from Germany quenched many people’s thirst for this drink—after it suggested that tapioca pearls may cause cancer. Very quickly, media around the world picked this up and reported its conclusions as a factual discovery.
Let’s take a careful look at this study and the reporting on it. Researchers from the University Hospital Aachen tested tapioca balls from an unnamed Taiwanese chain, and found the chemicals styrene and acetophenone as well as non-specified substances attached to the element bromine. The lead researcher of the study and many media sources identified these substances as belonging to a class of compounds called PCBs (polychlorinated biphenyls). And that set the ball rolling because the U.S. Environmental Protection Agency has concluded long ago that exposure to PCBs can cause cancer in animals. Some studies on workers exposed to PCBs found that PCBs are associated with liver cancer and malignant melanoma. But, keep in mind that association does not mean cause.
The Taiwanese government soon became involved in this imbroglio—a lot of money was at stake. The Consumer Protection Committee in Taiwan did a round of testing, collecting 22 samples of tapioca pearls from seven manufacturers, and concluded that none contained styrene. The agency did find brominated biphenyls and acetophenone, but the quantity was too small to create any health concerns. Unfortunately, the sample size was very small and the details of their analysis have not been made available.
The U.S. Food and Drug Administration (FDA) also weighed in. According to Noah Bartolucci, an FDA spokesperson, acetophenone and styrene are not PCBs because they are neither chlorinated nor biphenyls. “Both acetophenone and styrene are aromatic compounds (PCBs are also aromatic), but being an aromatic compound is not, in and of itself, a reason for toxicological concern,” he said. In other words, both the investigators and the media incorrectly identified these substances as being part of a potentially dangerous class of compounds.
Not only are acetophenone and styrene not classified as PCBs, but they are legally permitted to be added to food as synthetic flavoring substances, and are regulated as such by the FDA. As Bartolucci explained, “The FDA conducted a safety assessment for each of these substances before they could be used in food intended for the U.S. market.”
As for the substances in the tapioca that contained bromine, the German report did not name them or specify their quantity. In fact, the researchers failed to note how much of any of the substances they found in the tapioca pearls, which is important because, as the phrase goes, it is the dose that makes the poison.
In addition, the German report was not published in a peer-reviewed journal, so the study itself was not evaluated by other scientific experts to ensure its accuracy. If a study is not published in a peer-reviewed medical or scientific journal, it's best to treat the findings with a grain of salt.