Movies like Contagion and antibiotic-resistant germs like MRSA don't help assuage fears of rampant germ proliferation; but if you tend to reach for the hand sanitizer every time you touch an elevator button, doorknob, or dumbbell, curb your enthusiasm. There's good reason to take it easy with these chemical-laden germ killers. They frequently contain triclosan, a chemical that many consider to be an obesogen—i.e., one that can potentially cause weight gain by disrupting the body's endocrine system.

"Animal studies indicate that triclosan can affect thyroid function," says Tom Zoeller, an endocrinologist and professor of biology at the University of Massachusetts--Amherst. "It's plausible that triclosan can interfere with thyroid hormones in people, though it's not been well studied." The chemical structure of triclosan is similar to that of the thyroid hormone itself—one reason it could interfere with the body's natural thyroid levels. Thyroid hormones control metabolism, so if you reduce thyroid function, you can gain weight—not a situation you want to unwittingly create as you try to stay healthy, fit, and germ-free.

To cut down on exposure, wash your hands with good old soap (not the anti-bacterial variety, which often contains triclosan, too) and water whenever possible, and choose a triclosan-free sanitizer when on the go. These options, below, kill germs with natural, botanical agents:

• CleanWell All-Natural Hand Sanitizing Wipes

Available in individual-use totables, these wipes rely on oil extracted from the thyme plant rather than triclosan to kill germs—and they're safe for the face, too. Stick them in your gym bag, and occasionally use them to wipe down your grimy phone.

• Burt's Bees Aloe & Witch Hazel Hand Sanitizer

Here, the witch hazel acts as an antiseptic, while the aloe moisturizes your skin. The combo claims to obliterate 99.99 percent of germs—you can't get much better than that.

• Artemis Antiseptic Foam Hand Sanitizer

Serious-sounding sanitizing comes from this "USA FDA category III compliant" germ zapper. The moisturizing formula kills E. coli, MRSA, and other common germs. Translation for you: Healthier, softer hands.

• Clean George Hand Purifier

This synthetic-free spray of Manuka, tea tree, and peppermint oils eliminates germs without stripping the good bacteria from your skin. A three-pack of Grapefruit n'Sage, Lovin' Lavender, and Mint-alyptus keeps you scented and sanitary.

• Honest Hand Sanitizer

Safe for babies, kids, and you, this gel from Jessica Alba's natural products company has an alcohol base (thickened with vegetable glycerin and wood cellulose). Added for moisture are aloe and vitamin E, but no harsh chemicals.

For more information about triclosan, the Environmental Working Group, a nonprofit focused on the environment and public health, offers a guide.

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