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.
One reason why the media may have hyped this story on tapioca pearls is because Taiwan has been no stranger to controversies about contamination in food products. In 2011, a scandal broke outin Taiwan when traces of DEHP were found in drinks and other food products. DEHP, whose full chemical name is bis(2-ethylhexyl) phthalate, is one of a common class of plasticizers (used to enhance characteristics like flexibility and stretchability in plastics) that was classified as carcinogen in 1988 by the California Occupational Health and Human Services and is also suspected of being an endocrine-disrupting chemical. In this case, the Taiwanese government launched a major investigation in June 2011 and removed all products that may have contained DEHP.
The FDA also increased its surveillance of food products from Taiwan. As of July 2013, no further problems have been reported about food products imported from Taiwan.
This story is a classic example of how incomplete and incorrect information can go viral, causing unnecessary fear. I would certainly like to know the types and amounts of bromated compounds the German researchers found, along with many more details about their study. I would also like to know exactly what the Taiwanese government studied and the quantitative results.
Having said that, if, in the back of your mind, you’ve been worried about boba milk tea but haven’t stopped drinking it, you can stop worrying. Or, if you are avoiding boba milk tea or tapioca pearls because of concerns about cancer, you can resume buying the drink. This “study” simply does not warrant the kind of fear it has generated.
There are, however, other health factors to keep in mind. Tapioca pearls contain mostly carbohydrates from starch and have little nutritional value. A cup of pearls contains 540 calories, so adding ¼ cup of them to milk tea translates into an additional 135 calories. As with sugary drinks, consuming boba tea too often might undermine an otherwise healthy diet. A good balance is the key. As for me, I still buy (and enjoy) the drink—but only in moderation.