Tea is one of the most widely consumed beverages in the world, enjoyed by billions of people every day. However, a recent scientific review suggests that a simple cup of tea might contain more than just brewed leaves. Researchers have found that some tea bags can release massive numbers of tiny plastic particles during the brewing process.
The review analyzed findings from 19 different scientific studies and explored how microplastics and nanoplastics may enter tea. These particles, collectively referred to as MNPs, are extremely small. Microplastics measure between one micrometer and five millimeters, while nanoplastics are even smaller than one micrometer, making them invisible to the human eye.
Scientists say these particles can reach tea through several pathways, including packaging materials, production processes, brewing equipment, and even airborne contamination. However, tea bags themselves appear to be one of the most significant sources.
Many tea drinkers assume that tea bags are made entirely from paper, but this is not always the case. Some tea bags, especially pyramid-shaped sachets, are made from plastic mesh materials. Others combine plant fibers with plastic components, while some cellulose tea bags contain polypropylene used as a heat-seal layer to keep the bag closed when placed in hot water.
Even products labeled as compostable or biodegradable may still contain plastic elements. In several studies, scientists dissolved the cellulose components of certain tea bags and still detected remaining plastic particles.
Some of the findings from these experiments are striking. In one laboratory test, a single plastic tea bag released around 14.7 billion micro and nanoplastic particles during brewing. Another study reported approximately 1.3 billion particles released from a single bag under similar conditions.
The exact numbers vary widely between studies because researchers use different laboratory methods. For example, filters used to collect particles may have different pore sizes. Larger filters capture bigger plastic pieces but allow smaller ones to pass through, while finer filters detect much smaller particles. This difference alone can significantly affect the final counts.
Scientists also emphasize that detecting microplastics is technically challenging. Researchers must not only collect particles but also confirm that they are actually plastic and determine the specific polymer type. Laboratory contamination is another concern, as fibers from clothing, plastic lab equipment, or dust in the air can accidentally enter samples.
Beyond the particles themselves, researchers are also examining chemicals associated with plastics. Many plastics contain additives used to improve durability, flexibility, or color. Some studies detected plastic-related chemicals such as plasticizers and bisphenol-type compounds in brewed tea.
However, experts stress that the presence of these particles does not automatically mean they are harmful to human health. The review did not include clinical trials involving people. Instead, it referenced early laboratory experiments conducted on small aquatic organisms and human cell models.
In one study, tiny aquatic organisms called *Daphnia* were exposed to water containing particles that had leached from nylon and PET tea bags. Scientists observed changes in body structure and swimming behavior at higher exposure levels, although other substances from tea leaves may also have influenced the results.
Another experiment tested bioplastic particles from PLA tea bags on human intestinal cells. Researchers found that the cells interacted with the particles, but short-term tests did not show significant cell damage or structural harm at the concentrations studied.
Experts say these findings should not cause immediate alarm but rather encourage further investigation. The details of brewing conditions, tea bag materials, and testing methods all influence the results. While tea remains a popular and generally safe beverage, scientists believe understanding how packaging materials interact with hot liquids is important for consumer health and product design.
The full research review discussing these findings was published in the scientific journal Food Chemistry.