🍵O Estudo do Chá Com "11 Bilhões de Microplásticos" Estava Errado por 1000x
Aquele estudo que assustou todo mundo dizendo que cada xícara de chá libera 11 bilhões de partículas de microplástico? A agência alemã de segurança alimentar refez o experimento e encontrou 1.000 vezes menos partículas. --- O problema estava no método: os pesquisadores originais evaporaram a água do chá para examinar o resíduo. Quando a água evaporou, resíduos químicos dissolvidos do processo de fabricação da saquinha secaram e endureceram em pequenas partículas. O microscópio contou essas partículas como plástico - mas elas eram químicos dissolvidos, não plástico flutuando no chá. Além disso: o estudo testou só as saquinhas de seda piramidal de nylon e PET, que representam 5% do mercado. A saquinha retangular comum que a maioria usa é feita de polpa de madeira.
Germany’s food safety agency called this study’s lab method “completely unsuitable for testing for microplastics.” When they repeated the experiment properly, they found 1,000 times fewer particles. Here’s what happened. The “11.6 billion particles” number comes from a single 2019 study at McGill University in Canada. The researchers steeped plastic tea bags in hot water, then evaporated all the water so they could examine what was left under an electron microscope. The problem is that when the water dried, dissolved chemical residue from the bag’s manufacturing process hardened into tiny specks. The microscope counted those dried-out specks as plastic particles, even though they were dissolved in the liquid like sugar dissolves in coffee. They were never actually floating around as pieces of plastic in your tea. Germany’s Federal Institute for Risk Assessment (BfR), their version of the FDA for food safety, caught this in 2020. They repeated the experiment but used a method that checks each particle one by one to confirm whether it’s actually plastic. They found 5,800 to 20,400 particles per bag. Not 11.6 billion. A 2025 review paper co-authored by BfR researchers straight up called the original numbers “preparation artifacts,” meaning the particles only showed up because of how the lab samples were prepared, not because of the tea. Two more things the tweet leaves out. First, the study only tested premium silky pyramid bags made from nylon and PET plastic. Those bags represent about 5% of the tea bag market. The flat rectangular tea bag most people actually use is made from wood pulp and abaca fiber, a plant from the banana family. Brands like Bigelow, Numi, Stash, Yogi, and Traditional Medicinals all use plant-based bags. Bigelow alone makes 2.2 billion tea bags a year with zero plastic. Second, the total weight of all those “billions” of particles in the original study was 16 micrograms. That’s 16 millionths of a gram. A single grain of sand weighs about 50 times more. No major health authority, not Germany’s BfR, not the European Food Safety Authority, not the WHO, has concluded that microplastics in food cause health problems at the levels people are currently exposed to. The study is real. The number is probably wrong by a factor of 1,000. And it tested a product most tea drinkers don’t use.
— @AnishA_Moonka View on X