Tea bags are a convenient method for brewing the world’s most popular beverage, but their materials have become a source of health concern. Whether tea bags are unhealthy is not about the tea itself, but rather the construction of the sachet holding the leaves. Modern tea bags come in two main forms: traditional paper-fiber squares and newer mesh or pyramid-shaped bags. Health concerns generally revolve around chemical residues leaching from the fiber-based bags and the physical release of plastic particles from the synthetic mesh bags. The materials used in manufacturing can introduce contaminants that enter the hot water during the steeping process.
Chemical Residues and Manufacturing Concerns
Traditional paper tea bags often contain epichlorohydrin, a chemical used as a wet-strength resin to prevent the paper from dissolving when submerged in hot water. This substance is classified as a probable human carcinogen based on animal studies, and it can hydrolyze, or change form, when it contacts water. Studies have shown that the levels of epichlorohydrin released into tea infusions can be significantly higher in bagged teas compared to loose leaf teas.
The paper used in many tea bags is bleached to achieve a clean, white appearance, which introduces another potential source of contamination. Older bleaching processes utilized chlorine, which can result in trace amounts of dioxins, known carcinogens and persistent environmental pollutants. Although manufacturers increasingly use Elemental Chlorine-Free (ECF) processes, the white color still indicates intensive chemical treatment. Unbleached paper, which has a tan color, avoids this chemical process entirely.
Beyond the bag material, the tea leaves themselves can carry residues that transfer into the final drink. Tea is often treated with pesticides during cultivation, and these residues remain on the dried leaf material. Testing has revealed that many commercially available teas contain multiple pesticides. These agricultural chemicals can then infuse into the hot water along with the tea’s beneficial compounds.
Microplastic Release from Synthetic Tea Bags
A distinct concern arises from the newer, mesh or pyramid-shaped tea bags, which are frequently made from synthetic materials like nylon or polyethylene terephthalate (PET). These plastic polymers are used because they are durable and allow the tea leaves more room to expand. However, when these synthetic bags are steeped in near-boiling water (around 95 °C), they release an enormous quantity of microscopic plastic particles.
Scientific research has demonstrated that a single plastic tea bag can release approximately 11.6 billion microplastic particles and 3.1 billion nanoplastic particles into a cup of tea. These levels are significantly higher than plastic loads previously reported in other foods and beverages. Microplastics are small particles measuring less than 5 millimeters, while nanoplastics are even smaller. The long-term health effects of ingesting these high concentrations are still being studied, but this represents a physical contaminant unique to these synthetic materials.
Identifying Safer Materials and Alternatives
Consumers seeking to reduce their exposure to these contaminants have several options, starting with examining the bag material. The most straightforward alternative is to switch to loose leaf tea, which eliminates the bag entirely and requires only a reusable strainer or infuser. This method ensures that the only thing steeping in the cup is the tea leaf itself.
For those who prefer the convenience of single-serving portions, certain tea bag materials are generally considered safer.
Safer Tea Bag Materials
- Look for bags that are explicitly labeled as unbleached, which avoids the chemical bleaching process.
- Choose bags made from natural materials like organic cotton.
- Select bags made from non-GMO corn starch Poly Lactic Acid (PLA), often referred to by the trade name Soilon. While PLA is a bioplastic, it is derived from fermented plant starch and is intended to be biodegradable, though it requires specific industrial composting conditions to fully break down.
- Choosing tea brands that specify their bags are heat-sealed without glues or staples also helps to avoid potential trace chemical migration.
- Selecting certified organic tea leaves, whether bagged or loose, further reduces the likelihood of pesticide residues transferring into the final brew.