Scientific Study: Double Dipping Is As Gross As You Think It Is

If you object to George Costanza’s habit of double dipping—now you have a scientific study to back it up.

The study was conducted by Prof. Paul L. Dawson, a food microbiologist, who decided to experiment with “double dipping” after watching a Seinfeld re-run in which a character named “Timmy” objects to George’s dubious dipping habits.

Professor Dawson told the New York Times that he expected “little or no microbial transfer” as a result of double dipping.

He was wrong.

Double dippers are just as gross as you’ve always suspected:

The team of nine students instructed volunteers to take a bite of a wheat cracker and dip the cracker for three seconds into about a tablespoon of a test dip. They then repeated the process with new crackers, for a total of either three or six double dips per dip sample. The team then analyzed the remaining dip and counted the number of aerobic bacteria in it. They didn’t determine whether any of the bacteria were harmful, and didn’t count anaerobic bacteria, which are harder to culture, or viruses.

There were six test dips: sterile water with three different degrees of acidity, a commercial salsa, a cheese dip and chocolate syrup.

On average, the students found that three to six double dips transferred about 10,000 bacteria from the eater’s mouth to the remaining dip.

Each cracker picked up between one and two grams of dip. That means that sporadic double dipping in a cup of dip would transfer at least 50 to 100 bacteria from one mouth to another with every bite.

Yuck. So, what now? “The way I would put it is, before you have some dip at a party, look around and ask yourself, would I be willing to kiss everyone here? Because you don’t know who might be double dipping, and those who do are sharing their saliva with you,” says Professor Dawson.

Dip Once or Dip Twice? [NYT via WSJ Health Blog]


Edit Your Comment

  1. Szin says:


    Man, gotta love these studies in the name of SCIENCE!

  2. Wow, so double dipping is worse than backwash. Science, it’s FANTASTIC!

  3. bobpence says:

    I sometimes dip the other end of the item to be dipped, after the initial dip: Dip, bite, rotate, dip, munch. Germs move slowly.

  4. MercuryPDX says:

    There’s now a market for “No Double Dipping” signs, just like the “No Fishing” ones in the bottom of fishbowls.

  5. shan6 says:

    I should have kept my head in the sand on this one!

  6. MercuryPDX says:

    Damn… shoulda googled first:

  7. matt says:

    “Would I be willing to kiss everyone here?”

    At some parties…..I can get that way.

  8. B says:

    Also gross as you think it is: Eating food out out of the garbage and peeing in the shower.

  9. frankieman70 says:

    I should not have read this, My wife is right, :(

  10. floydianslip6 says:

    Well yeah the bacteria from your mouth gets in the dip… but who gives a shit? For a double dipper it’s no surprise that the bacteria is in there, I just don’t care. Gives the ol’ immune system a work out.

    Aside from that, 3 seconds seems like a real long dip time.

  11. coan_net says:

    And my wife got mad at me when I coughed on the dip – now I can tell her – SEE, at least I did not double dip! :-)

  12. floydianslip6 says:

    @B: Peeing in the shower isn’t dirty. It’s all waste water and urine is sterile.

    • floraposte says:

      @floydianslip6: Urine is sterile in the bladder, so long as the person has no infections. Urine picks up microorganisms as it comes in contact with the skin and leaves the body, and, of course, it may not have been sterile in the first place.

      So, not so much.

  13. B says:

    @floydianslip6: Pee in your own shower then, and stay out of my gym.

  14. lincolnparadox says:

    According to a Swedish study on Oral Hygiene, performed by their state pharm agency, up to 40,000 parasites (bacteria, viruses, etc.) can be transferred through one mintue of “French kissing.”

    Now, I couldn’t find the original reference for this, but personally, I’d be more worried about the coliform bacteria on people’s hands from their last bathroom trip, rather than whatever is in their spit.

  15. floydianslip6 says:

    @B: well a PUBLIC shower has the issue of other peoples personal feelings. I ain’t peeing in a public shower out of consideration for others. But it still ain’t dirty.

  16. Ozyman says:

    I wonder about the peeing in the shower bit. I know urine is sterile, but it is also a great fertilizer. Is it possible that peeing in the shower will promote growth of that nasty stuff (mold, mildew, fungus???) that makes the bottom of the shower sticky?

  17. ClayS says:

    Did they really need to do a study to know that bateria is going to be transferred into the dip? What could be more obvious?

  18. cobaltthorium says:

    I love peeing in the shower – it’s so efficient. Of course, I have the common courtesy not to do it in other people’s showers.

  19. ncboxer says:

    Have the also done a study to figure out how many bacteria is transferred during oral sex? I would say double dipping is a lot safer.

  20. snoop-blog says:

    yeah i could just finish peeing, get in the shower, and have to go again. it’s like it was supposed to be.

  21. Antediluvian says:

    And this is the general reason I cringe when I see people pick up ice cubes with their hands, grab a big handful of chips or crackers, or pick up M&M’s from a bowl. It’s not just the lips that are bacteria-laden, folks. Hands will transfer them too, and sometimes more interesting critters: Hep A, fecal coliform, etc. That’s why hand washing is important.

    It’s also why I no longer put out bowls of M&M’s or similar candies, only wrapped ones, and always have tongs or a cup in an ice bucket. I’m also wary of bowls of chips.

  22. cobaltthorium says:

    I love oral sex – it’s so efficient. Of course, I have the common courtesy not to do people in public.

  23. DavidS722 says:

    IIRC, the exact same study published a couple of months ago with the complete opposite conclusion.

  24. ClayS says:


    Double-dipping during oral sex? That could be a number of things.

  25. Antediluvian says:

    @ncboxer: That’s why orgies are awkward — all the body part washing in between partners.

    Like the old Mainer joke, found here in Newfie form. Just replace Newfie with the ethnicity or region you dislike, and enjoy.


    The 80 year-old manager of a rodeo needed a new bull, so he perused the newspaper and found a farmer selling one. Upon contacting the farmer, he was informed that the bull would cost $1500. The manager agreed, and drove out with a vet to inspect the bull. The vet declared the bull to be healthy, so the manager purchased the bull.

    Three months later, the bull suddenly went cross-eyed. The manager, in a panic, phoned the vet, who recommended he contact the farmer. So the manager phoned the farmer, who said to come on out, that he could fix the bull right up. When the manager arrived with the bull, the farmer went into the barn and returned with a rubber garden hose. The farmer proceeded to insert one end of the hose into the bull’s anus, put his mouth to the other end, and blow hard. The bull’s eyes instantly became un-cross-eyed. The farmer told the manager that it would be $50, so the manager paid the farmer.

    Three months later, the manager noticed the bull had gone cross-eyed again, so he went to see the farmer again. The farmer repeated the routine, and charged him another $50.

    Three months later, the manager again saw that the bull was cross-eyed. However, this time, instead of going to see the farmer, he grabbed his Newfie rodeo-hand and decided to do it himself. The Newfie and the manager went to the storage closet and grabbed a garden hose, and went to the bull. The manager said, “You go ’round in front and watch his eyes, and tell when he’s fixed.” So the Newfie went in front and the manager went behind, inserted the hose into the bull’s anus, and blew as hard as he could. However, being 80, that wasn’t hard enough, and despite blowing and blowing, he finally gave up.

    “You try blowing,” said the manager to the Newfie. So the Newfie came to the back and the manager went in front.

    After a few minutes of nothing happening, the manager went to see what the Newfiew was doing. He was shocked to see the Newfie removing the hose from the bull’s ass and turning it around. “What are you doing?!?” demanded the manager, “He’s not fixed yet!”

    The Newfie looked up and replied, “What? You think I’m going to put my lips on the same end you used?”

  26. RvLeshrac says:


    Peeing in someone else’s shower is less disgusting than using someone else’s shower. Urine is sterile, your body is not.

  27. RvLeshrac says:


    Cups and tongs in an ice bucket are no more sanitary than just reaching in with your hands.

    This is why health departments have rules against leaving the scoop in the ice machine.

  28. Kenneth says:

    OK, I get that double dipping transmits bacteria, and fingering the M&M bowel is sketchy too. I don’t double dip in public. But seriously folks, a little bacteria is not going to kill you. A few germs every now and then will build up your immune system. No wonder our kids are so allergic to everything.

  29. ncboxer says:

    @ClayS: No, double dipping for chips/crackers.

  30. faust1200 says:

    @Kenneth: So you won’t mind if i take a dump on your post in the name of biotic health. ::squirtch::

  31. Kenneth says:

    @faust1200: eww grossssss!! Seriously, within the context of the discussion please. Besides, I’m not into that.

  32. lostalaska says:

    Double dipping in a communual bowl is gross. There was some low end news journal show on TV that did a test on like 40 different businesses ice cubes from their soda machines for fecal matter. The findings was that 70% of the businesses tested had fecal particulate in the ice cubes from soda machines they said this is most often caused by employees not washing their hands before handling the soda fountains. The scary thing is how long it lasts in those machines if they aren’t cleaned up really well.

    Mmmm it’s just about lunch I’m gonna go get a sandwich and some diet fecaloda.

  33. RandomHookup says:

    This study has Ig Nobel Prize written all over. Alert the jurors!

  34. nardo218 says:

    I wonder how much bactria you swap when you kiss someone. Because 50-100 of a microscopic single celled organism doesn’t sound very dangerous.

  35. NefariousNewt says:

    @nardo218: Not sure how much, but boy it sure is fun swapping them.

  36. HykCraft says:

    Gross. It’s like teabagging.

  37. PatrickIs2Smart says:

    @B: Ahh, the lessons in life that Seinfeld has taught us…

  38. savvy999 says:

    @nardo218: Exactly. Every second of every day our bodies’ immune systems are staving off infection from trillions of microorganisms; double-dipping adding another 100 isn’t going to do squat. A reasonable estimate is that the human body has about 10^14 (that’s 100,000,000,000,000!) bacteria present in or on it at any given time. []

    Except for the terminally OCD or those suffering from an auto-immune disorder, this is an utter non-issue. I would gladly eat double or even triple-dipped guacamole with all of you.

  39. urban_ninjya says:

    @bobpence: That’s even more gross. Your dirty fingers touched the end of that thing.

  40. Antediluvian says:

    @RvLeshrac: I was thinking cups and tongs for ice at parties, not at McDonald’s or the local Motel 6.

    I’m personally fine with double-dipping with people I have sex with. I figure it’s kinda like foreplay, but slightly removed.

  41. TechnoDestructo says:


    You keep right on saying that until you get mouth herpes from cheese dip.

  42. faust1200 says:

    What ARE germs? Check out this informative short film.


  43. AcidReign says:

        This is an amusing topic! I tend to side with the folk above who believe that you can’t live in a sterile bubble. You push open a door at the supermarket, or touch the cart, and you’re infected. Hopefully, your immune system is tuned up, and will handle it!

        On the other hand, I’m not volunteering to lick a spittoon. Salsa’s tomato-based, isn’t it? That acid should kill germs pretty quickly.

        Most parties I go to have pretty rancid dips, anyway. You’d think people could put out salsa, or even an easy/sinful ranch/sour cream dip, but nooooo. Most of the dips I’ve seen this year resemble coarsely chopped colon. Ick. Mix me another scotch on the rocks, instead.

  44. firefoxx66 says:

    50 to 100 bacteria!??!?! OH NOES!!!

    You probably inhale that much every hour. calm down everybody. unless someone you’re double-dipping with has some fairly virulent, nasty disease, you’ll be cool.

    Swiffer Anti-bacterial and Purell would like you to think differently, but we DO have an immune system. And, it works.

  45. @firefoxx66: i was going to say the same thing. 10,000 bacteria are *nothing*. it’s just a fu**in’ appetizer to our immune system.

  46. geek22 says:

    According to this slate article Americans are too hygienic and have a weakened immune system as a result.


  47. MercuryPDX says:

    @faust1200: DUCK and COVER!

  48. reviarg says:

    This really doesn’t seem like a lot of bacteria. Seeing the original paper would be nice as well since I don’t see anything written about a set of control dips. Bacteria may have arrived in the dip just due to exposure to air or if somebody put their finger on a chip and then dipped the end of the chip they touched. This is interesting work though and it would be interesting to read the final paper if it gets published.

  49. DrGirlfriend says:

    You know, the thing is, I could care less about double dipping. It doesn’t bother me.

  50. Ghede says:

    Oh my. How terrifying. Bacteria. As long as the person double dipping isn’t sick, what harmful bacteria from their mouth will endanger your mouth? Make no mistake, it is gross to others and it is courtesy to not double dip. However, most bacteria is perfectly harmless.

    Unless you decide to go overseas. Then they are all flesh-eating, highly-contagious, and as soon as you arrive, the locals lick your scalp. Then they jab you with needles and laugh.

    @geek22: Yeah. I never get sick and I eat food off the floor (Five second rule is BS, but I use it as an excuse anyways.)

  51. shoegazer says:

    Meh. Your immune system needs practice.

  52. theblackdog says:

    *shrug* I take reasonable precautions against bacteria, such as washing my hands and making sure the cutting boards are cleaned in hot soapy water after use. However, I know there’s bacteria out there and so picking up a few more from a dip aren’t going to matter much.

    Anyone remember the Mythbusters where they tested for the fecal coliform bacteria on toothbrushes in various places in the bathroom? Even the “control” toothbrushes that were kept in a sealed container in a completely different room tested positive for the bacteria.

    Hell, I think one of the reasons I rarely get sick these days is because I wasn’t doused in all the antibacterial crap from day one.

  53. floydianslip6 says:

    @TechnoDestructo: Looks like someone has been to the players ball.


  54. Witera33it says:

    According to OSHA, 1 out of 4 people who have hepatitis know that they have it. It is a very easy to transfer virus and it lives forever.
    I said it before and I’ll say it again. Hand washing is the single best way to prevent the spread of anything.
    OSHA approved method of hand washing: Wet hands, apply soap, lather for at least 2 rounds of “row your boat”making sure to get thumbs and wrists, rinse with hot water. Turn off spigots with towel and open towel with towel.

  55. jmschn says:

    damn..i was eating my lunch while reading…well, that wraps up my half uneaten food…

  56. bhall03 says:

    I am surprised that nobody thought it interesting that someone would dip a chip or cracker for 3 seconds…were they trying to drown it?

  57. bhall03 says:

    @jmschn: Can I have the rest of your food?

  58. theoxygenthief says:

    50 bacteria is more likely to do you good than harm you…..

  59. metalmarious says:

    It only really matters if the bacteria cause illness because your mouth has its own bacterial flora anyway,

    I hate double dipping(and other similar ways of sharing food) but bacteria are all over the place, you rarely get sick from this.