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Q. When I asked my new roommate if we could switch to regular dishwashing liquid from our pure castile soap, she said she would rather not because she was “bug friendly.” I’m a fond lover of the flora and fauna myself, but I don’t want to get a foodborne disease that would be avoided by using a stronger soap. I even wonder if the awful cold I caught from her was from not using disinfecting soap on our dishes. Why is my roommate insisting on using castile soap? Does it work?

Dishwashing Dilemma
San Francisco, CA

A. Dearest DD,

You’ve identified what I think is a common concern among the eco-conscious. Of course we want to choose nontoxic, non-polluting products … but do natural cleaning alternatives actually, you know, work? This is especially acute when health issues — not to mention matters of domestic tranquility — are on the line.

Get ready for a cooling of tensions in the kitchen, DD: Your pure castile soap is just fine for dish duty. To explain why, let’s reacquaint ourselves with the purpose of soaps, whether they’re meant for your hands, body, or the pot with the burned-on crud stuck to the bottom. It’s not to kill pathogens. Rather, soap chemically binds with grease and germs, then yanks the offending nasties down the drain in a swirl of hot water. (It does this so effectively, simple handwashing is the centerpiece of a global campaign from the World Health Organization.) And castile soap, a veggie-based and biodegradable concoction, stands right there with your “regular” varieties.

I’m in no position to definitively explain your roommate’s soap preferences, but I can speculate. (And while we’re speculating, I’m assuming you’re talking about antibacterial dish soap when you say “disinfecting.”) Guess  No. 1: Antibacterial soap isn’t really necessary, say the Centers for Disease Control and Prevention and the Food and Drug Administration. The stuff just hasn’t been proven to prevent illness any better than the usual lathers.

Guess No. 2: Antibacterial soaps have some disturbing side effects. Most get their germ-busting chops from none other than triclosan, an antibacterial chemical that’s been getting a lot of bad press lately (we’ve recently touched on the substance’s role in toothpaste and shampoo). The charges: disrupting hormones, building up in our rivers and oceans, and contributing to the development of antibiotic-resistance bacteria. In fact, just today the FDA announced that makers of antibacterial soaps have a year to prove their ingredients are safe — or the antimicrobial chemicals therein must be pulled from the products. It could be your roomie has run her own odds and decided scrubbing up with antibacterial suds is a dirty business.

But you’re worried about spreading illnesses around your happy home, DD. (I don’t blame you, and neither does anyone else who’s ever come down with a bad case of the green-apple two-step.) Science says that antibacterial soaps won’t keep your hands or your dishes any cleaner than the regular stuff, but there are some steps you can take to keep the bugs from crashing your next dinner party.

Using hot water is key to battling any germs clinging to your forks — a dishwasher is best (and saves water!), but handwashing is okay too. Sponges and dish towels are like Club Med for bacteria, so boil or wash them in hot water frequently and let dishes air-dry when you can. You can also use a bleach solution to further sanitize your flatware, but really, this is overkill unless someone in the house has a compromised immune system.

As to your question about catching your roommate’s cold — well, there are about a million ways you could have come in contact with her pathogens beyond the dishes, including touching pretty much any surface in your home or standing too close to her last sneeze. This is also a good place to point out that colds are caused by viruses, which wouldn’t have been killed by antibacterial dish soap anyway. So wash those hands even more often than you wash those dishes — castile soap works just fine here too — and try not to worry too much. Stress does weaken the immune system, after all.

Microbially,
Umbra