Perhaps you wouldn't dream of microwaving plastic food containers, because you know the heating plastic can allow toxins to leach into your food. But you probably don't think twice before dunking your fancy mesh tea bag into boiling-hot water. Well, you may want to give that some thought right now.

Yes, those pyramid-shaped mesh sachets filled with pretty multi-hued leaves lend sophistication to your daily tea-drinking ritual.

But: Even though they're often called "silky," those bags aren't made from silk. Most are actually made from plastic, either polyethylene terephthalate (PED, polylactic acid (PLA, or "corn plastic") or food-grade nylon (indeed, nylon is a plastic).

PET, PLA and nylon are widely used for food packaging, and their safety as packaging materials has been tested. "However, when you subject plastics to stressors such as heat, the molecules begin to break down and they can leach-no matter whether it's a microwave oven or a cup of hot water that is warming the contents," said Sonya Lunder, MPH, a senior analyst at the Environmental Working Group, an environmental health research and advocacy organization. "So, is stuff leaching out of the plastic in the tea bag and getting into your beverage? The answer is yes."

Problems with plastics: No studies have looked specifically at leaching from plastic tea bags, so we don't yet know how much of any particular toxin might be getting into our tea. But past experience should teach us to be wary. After all, people used to think it was perfectly OK to microwave food in plastic containers-until we learned that certain plastics contain bisphenol-A (BPA), an endocrine disruptor that has estrogen-like effects on the body and that has been linked to breast cancer, prostate cancer, diabetes, obesity, heart disease, liver disease, thyroid dysfunction, in fertility, early puberty, and cognitive and behavioral problems in children!

The plastics used for tea bags don't contain BPA. But PET plastics can contain phthalates (not because these chemicals are used as ingredients in the plastic, but rather because they may originate from recycled content)- and phthalates are another type of endocrine disruptor that has been linked to birth defects. There is also some concern that PET may leach antimony trioxide, a heavy metal. "We just don't know whether the amount of various substances in PET, PLA and/or food-grade nylon might someday prove to have negative health effects," Lunder said. ''As yet, there is no scientific consensus about what is too much, who is at risk or what other health effects we may be seeing from plastic food packaging. But given the worrisome potential effects on our hormones, I advise that people avoid heating plastics at every opportunity."

It boils down to this: If you enjoy an occasional cup of tea made from a fancy "silky" tea bag, you probably don't need to worry too much-that once-in-a-while treat isn't likely to hurt your health. However, it's possible that your body may reach potentially harmful levels of various chemicals if you are drinking tea made from plastic tea bags multiple times each day-particularly if you try to be frugal by making a second cup from a single tea bag, given that repeated stress in the form of heat can make plastics leach even more.

What about good old paper tea bags? They might not be any better than plastic because many are treated with epichlorohydrin, a compound that has been linked to cancer, infertility and suppressed immune function.

Your best bet: Buy yourself a nice metal tea ball. They typically cost only a few dollars. When you want a cup of tea, fill the ball with your favorite organic loose-leaf tea and let it steep in the mug. When the drink is as strong as you like, remove the strainer and enjoy your tea-worry-free.

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