Episode 135: Hidden Nasties

Air Date: December 16, 2009

It is feasible for a soda can to be contaminated with rat urine and subsequently transmit deadly viruses to humans.


To create a control sample, Adam and Jamie spread out 1,000 aluminum soda cans, cleaned the top surfaces of the cans, and released 40 rats to walk on them for 90 minutes. Viewing the cans under a black light clearly showed that many of them became contaminated with rat urine. Next, they collected 1,000 cans from a variety of locations across San Francisco. Viewing these cans under a black light revealed that most of them also had organic substances on them, but it was not clear what those substances were. To find out what was on the cans, Adam and Jamie took swabbed samples to UC Berkeley, where a mass spectrometer was used to identify the chemical compounds. As expected, the control contained 15 proteins that indicated rat urine. However, the test sample did not contain any compounds indicating rat urine. Furthermore, a professor of epidemiology at UC Berkeley explained that any dangerous viruses contained in rat urine would not survive on the exposed tops of aluminum cans.

Many objects that people touch every day are dirtier than a toilet seat.


Adam and Jamie chose a total of 8 objects to test for cleanliness: toilet seat, money, kitchen sponge, hotel room remote, computer keyboard, light switch, cell phone, and shopping cart. They swabbed each surface for 10 seconds and created Petri dishes from the swabs that incubated overnight. Their first method of measurement was to count the number of microorganism colonies on each dish. They found that the toilet seat sample actually had the fewest colonies, while the kitchen sponge sample had more than they could count:

  1. kitchen sponge (most colonies)
  2. money
  3. light switch
  4. computer keyboard
  5. hotel remote
  6. shopping cart
  7. cell phone
  8. toilet seat (fewest colonies)

However, they always wanted to account for the “nastiness” or harmfulness of the types of organisms on each Petri dish, so they had a microbiologist re-rank the samples. The list was as follows.

  1. kitchen sponge (most nasty)
  2. money
  3. light switch
  4. computer keyboard
  5. toilet seat
  6. cell phone
  7. shopping cart
  8. hotel remote (least nasty)

Finally, Adam and Jamie decided they needed a larger sample size to provide better results. They enlisted a group of biology students at UC Berkeley to collect more samples from the top five dirtiest surfaces. After collecting and analyzing these samples, the final list was as follows.

  1. kitchen sponge (most dirty)
  2. money
  3. computer keyboard
  4. toilet seat
  5. light switch (least dirty)

At 50 mph (80 kph), a sports car can launch off a small ramp and skip across a 100 ft (30 m) lake.


To test this myth, Tory, Grant, and Jessi built dug a 100 ft trench at the end of a test track and filled it with water. They did not have the means to use a Lamborghini, as shown in the movie, but settled for a car of similar size and weight. They equipped the car to drive by remote control and drove it off a small ramp at 50 mph. Rather than skipping, the car hit nose-first and flipped end-over-end. Grant explained that the stunt in the movie was likely achieved with a platform just under the surface of the water and with weights in the car to keep it level.

(This myth came from the movie Cannonball.)

At high speeds, a sports car can skip across a 100 ft (30 m) lake.


Tory, Grant, and Jessi again substituted an average car for a sports car, but equipped it with a nitrous oxide system to increase its top speed. Small scale tests showed that skipping worked better without a ramp, so no ramp was used for the full scale test. When the team drove the car onto the artificial lake, it skipped twice and continued driving on the other side.


  1. eric plunkett says:

    the lambo engine is not mounted in the front of the car unlike the one used in the show, that has a major effect on why the front of the car dropped and the car flipped

    • Clayton says:

      I just finished watching this ep and I had the same exact issue. While the 2 cars may weigh the same. Their weight distribution is different due to where the engines are located. Seeing that the lambo’s trunk is in the front and engine is in the back.. It’s definitely not going to dive off the ramp

      • Nour says:

        Great list. Oh Lordy.This is not helping my prolebm.I really need to de-clutter my blogroll, not add to it. Thank you, Robin. Thank you. Why do you have such great taste?!?!?! I LOVE me some not for church ladies fun . Been reading that since the first time you suggested it. Oh, those ladies are hilarious.

    • chefmo32986 says:

      I was thinking the same thing they need to redo that one

    • Kori Township says:

      Didn’t they use a Pontiac fiero? Mid engine vehicle. I thought it was a pretty close reconstruction.

  2. Frank Ferrara says:

    Thank you Eric. I have always enjoyed watching Mythbusters however they do make numerous mistakes. In this case, the mid mounting position of the Lamborghini engine. The episode even showed them removing the mid mounted engine from the Lamborghini model on the scale test. I am also surprised that they did not consider the depth of the water or the underpannel(skidplate) layout on any of the cars. They got lucky becuase the second car they tested with happened to be mid engine. It would be nice to see a little more accuracy in their tests.

  3. Matt says:

    Eric and Frank, the MythBusters claimed that their test car had the same weight distribution as a Lamborghini – at least showing that they did consider this.

  4. Wiscfan says:

    For the car skipping across the water, if you look at the movie clip you can see that there is not an actual ramp. Rather, the road is elevated a little higher than the water. I think they need to revisit this and find the minimum speed needed to skip the car across the water without a ramp.

  5. rgra66 says:

    Eric the full size cars they used were both fieros all production fiero were mid engine not front engine cars.

    • lyallstyle says:

      thats right. i’m surprised that it took anyone this long to notice this

  6. chuck says:

    Love your show,theirs some guy’s that are trying to immitate but none even come close ,hope you guys keep me intertained for years to come,Thanks Guys and Kari-Really need to get her back My family never misses a show…

  7. Drtracr16 says:

    First, I wanted to say, I love your show and think you do an outstanding job!
    In the movie, there were no ramps used. If you look more carefully, there was a DIP! The dip dropped down then back up above the water level slightly. What that did was; when the car dropped down in the dip and started back up in that of short distance, it loaded the front springs on the car, to make it rise higher than the rear. When you make that happen it does not matter where the engine is located or how deep, the water is for the first few skips. Although, I am sure a rear mounted engine would be better but no skid plates
    When it was re-enacted on TV, the ramp did not load the front springs as much as it did the rear, making it nose dive! I was watching the show almost yelling; that is not the way it was on the movie
    Please watch this scene and consider trying it again

    • Joshua says:

      I completely agree! The launch was entirely dissimilar, and in no way a reasonable test. They need to make contact with the water at an angle and velocity similar to that of the movie scene they’re testing.

  8. michael says:

    i would like to say hi and ive heard a myth that sound waves can make somthing float so i thought i would submit the myth and im australian

    • Al says:

      I think it was radio waves.

  9. john degeorge says:

    will you use less gas if the tailgate is down on a pick-up truck while driving on the highway ?????

  10. Sophie says:

    is time travel possible?

    • HolmeBass says:

      Absolutely. We all travel in time all the time- constantly moving forward into the future. Time travel to the past is not possible- please refer to works by Einstein and Hawking for the complicated but thorough explanations as to why.

      • dylan says:

        Einstien explains that time travel may be possible if we discover how to use outer space wormholes..which we are very far from doing.

  11. Hannah says:

    heyy myth busters,
    i have a science fair project to do in a month and i have no idea what to do for it… can u help me out??

  12. jim spath says:

    Love your show. The lengths you floks go to in order to satisfy your fans is awesom! Glad to see Miss Combs on the show. She IS a really good metal worker. When is Kari comiong back?

  13. bsheldon says:

    they already did the tailgate down mileage myth several times.. turns out better mileage with the tailgate up.

  14. Eric says:

    I still think they should do this again….they flashed up a pretty weak diagram of the two cars. What I got from it, was that the cars weighed the same…they may have said “weight distribution” but I want a test with a rear heavy car and no ramp. And I hate how precise they are…I mean, if you have to go an extra 10 mph to get it to work, do it. Who cares if that is not what your “analysis of the film” found the speed to be.

  15. Dray says:

    to Sophie:
    is time travel possible?
    I am not trying to be a smartypants, but you are traveling throught time right now on the journey of your life. Maybe a better question to ask is, “Is Time Travel to the past or future possible?”

    • Andrew says:

      I’m traveling to the future right now…one second at a time. I would, however, like to travel to the distant future!

  16. Bertie the Bunyip says:

    Hydroplaning is pretty simple, really.
    It’s almost entirely dependent on tire pressure. The square root of the tire pressure in PSI x 10 will give you the approximate speed in MPH that the tire will hydroplane. So a car with a typical tire pressure of 30 PSI will hydroplane at a speed of about 54 mph. At any speed below that it is going to penetrate the surface of the water.
    At speeds above that it will hydroplane, but the impact of the tire on the water will dictate the speed at which hydroplaning will be supported. In short, the higher the vertical speed when contact is made, the faster you have to be going to sustain hydroplaning. This is down to the surface tension of the water contributing to hydroplaning. hitting the surface hard will break surface tension, taking it momentarily out of the equation.

    • Andrew says:

      Breaking the surface of the water is why tires have tread. If you put on, say…racing slicks all the way around, you will not have as much surface breaking through. This is why surfboards are smooth!

  17. Dad says:

    I agree that the water skipping sports car needs to be revisited with no ramp. Hang on, was that not what the second test confirmed? Any road up. I consider the first test invalid in that the movie scene had no ramp, so it is irrelevant to bust a ramp version of the test. Sez-me.net

  18. Dad says:

    The sound wave suspending objects suggestion from Michael, sounds (pun was unintentional) like the vibrating plate agitation of dust and sand experiment. Perhaps it looks like it is floating above the plate. Due to the vibration being so fast you do not see much of the plate hitting the sand particles momentarily. Possibly. A big loadspeaker with ball bearings or BB pellets might make some interesting patterns.

  19. vw autoworks says:

    Looks like in the movie. I could be wrong , but it seems they have dug out a bit of land before the jump so the suspension and gravity were less of a concern. There’s is a slight dip that is long enough to let the gravity of the car to become lighter. Watch the dip as the car rises it the advantage of traveling not level but upwards with relaxed suspension. Since water is level this would be considered a small fall. What do you think?

  20. John Cory says:

    So the kitchen sponge was the most nasty but I’m curious, would the use of anti-bacterial soap make a difference in the results?

  21. Bernie says:

    In skipping the car the testers seemed to go about it the wrong way with the first car.
    1 Did they examine the under side of a Lambo? I would think it would be much smoother and flater than production car they used. With the final test car they “Woke up ” by modifying the under side.
    2 They mentioned that the test cars weight was the same as the Labmo but did not concider the rear to front weight comparison – I would think the Lambo rear weight to be front weight ratio would be much higher than the test car.
    3 VW autoworks has a good point. Starting with a ramp was not a good idea – I could not see a ramp in the movie.

  22. Rudolf says:

    How do you scale weight, length (was 1:12 here), speed; how are the factors interrelated?
    You cannot scale gravity, so how do they do all this correctly so you get an accurate scaled down result?

    • svenistoros says:

      You are absolutely correct. Only extreme circumstances allow for the scaling of gravity. To compensate for scale one must increase the Vi of a given ballistic object.

  23. Lennox says:

    The car that is in the film was mid engin and had a rea wing to drop the rea of the car down.

  24. joe says:

    what type of car did they use in the car skipping myth?

  25. DK says:

    Too many things wrong with this one… GRR!! The primary concern (NEVER addressed) is surface area vs. smoothness as skipping is an effect of surface tension far more than an effect of the whole “mass of displaced water pushing the car back up” explanation the show presented. Yes, that matters, but not nearly as much as the other considerations
    1) The underside of a lambo chassis is purposefully smooth for aerodynamic effect. The Fiero, not so much.
    2) While small scale models are cute, you cannot scale SPEED! Water resistance as tested is an effect of surface tension, which is affected by smoothness and area
    3) Anyone who has ever jumped any vehicle will tell you that you can dramatically affect it’s flight characteristics with the throttle while in air. If Grant kept the throttle pinned after hitting the ramp, he quite likely did as much to case the car to nose over as any weight distribution. If he had coasted, or, better yet, been in neutral, it likely would have done better at keeping level.

    • joe says:

      In #3, when you said that flooring the gas in the air would change the conclusion is not relevant. the ramp was the real problem.

  26. storm says:

    i never would have guessd money would be that nasty.

  27. jay says:

    the lambo has the engine in the front but the car
    had its engine in the front caused the car to flip forward they need a car with a engine in the back and the myith could happen

  28. Zach says:

    Id like to point out that if u watch it in slow motion the car isn’t skipping on water in the movie. there are 2 land pieces in the water. the car bounces on land. It doesn’t skip. so u should remake the episode lol. see if a car can skip on land :p. cause the movie isn’t showing it skipping on water.

    • Sanju says:

      Gosh I am behind the times! Very beatled congratulations Huma!!!These are beautiful! I made an un-iced four tier sponge wedding cake with jam and buttercream dressed with fresh flowers for a friend’s country garden wedding and with good doweling it was structurally sound enough to be displayed outside in some pretty strong winds! I love decorating cakes but I have to say their is something so very pretty about the simplicity of a sponge cake without icing.Good luck with all the preparations!!!Megxx

  29. Phil says:

    I agree with Zach who just ripped off my answer.
    I think I even saw a small shrub on the island.
    I expect then that the suspension was beefed up, because the car took off pretty quickly after the first bounce.

  30. Mike says:

    For the kitchen sponge I would like to know if there is a different result comparing a J-Cloth – cotton rag to the sponge and if you use hot water and dish sopt to rinse out the sponge does this remove azll tghe bacteria.

    • Julia says:

      Mike, I heard of a study that determined that bacteria were still present in a sponge after soaking it in bleach for some amount of time, I don’t remember how long, but it was at least 24 hours. When I heard about *that*, that’s when I stopped using sponges for my dishes or kitchen counters. (I no longer *have* sponges in the kitchen because visitors would use them on those surfaces.)

      A cotton rag will probably retain a lot less bacteria with proper washing. I use cotton rags (flatfold diapers, actually) right and left for cleaning things I used to use sponges for. For scrubbing dishes, I get nylon net at the fabric store, cut it into pieces about 1′ on a side, and those work fairly well as scrubbers, don’t scratch, and come clean in the dishwasher.

      I think the problem with sponges is that there’s an awful lot of surface area in them, and it doesn’t all get hit with whatever cleaning method anyone might try.

  31. tesfuw says:

    kitchen sponges are unrecognised yet center for pathogenic microorganisms. any way now i am dealing about kitchen sponge for my thesis.

  32. jupmod says:

    Well, to play devil’s advocate, the toilet gets cleaned often. Therefore, the amount of bacteria one will find in a *clean* toilet will obvious be less than the light switch, shopping cart, or other items that do not get cleaned like the toilet. The myth pretty much IMO makes no sense in light of the differences.

  33. zonefloor says:

    what year were those Fiero’s? Quite the durable ride, eh?

  34. bonzo mcgill says:

    Would love to see the rank of dirty places. Like Schools, Airports, automobiles, portable potty, day cares. Could be done statistically by people numbers yet there may be surprises there.

    Did you check children’s toys at day care.

  35. Tim says:

    They should check the dirtiness of things like “automatic” sinks, paper towel dispensers, toilet flushers, light switches, etc…

  36. MikeA says:

    As a microbiologist I can unequivocally say that the only myth is that a kitchen sponge is the dirtiest thing in your house. I would ask what sponge was swabbed? Was it a properly kept and maintained kitchen sponge or the dirtiest one you could find?

    Here are the facts:
    1) A kitchen sponge should be sudsed with a dish cleaner, rinsed, and squeezed dry throughout the day.
    2) The sponge should be stored out in the open. For instance, store it in the sponge holder of your dish rack (not in the drawer under the sink – or anywhere that is dark and damp).
    3) The sponge should be made thoroughly wet and microwaved for two minutes after each use on raw food items; and at least once a day if no raw food is being cleaned. BTW, microwaving does work. What nonsense to say that it’s ok to microwave chicken in order to kill all potential salmonella but you can’t do the same thing with a sponge. As long as the sponge is thoroughly wet, and you microwave for two minutes it will become sterile. Remember, microwaves work by exciting water molecules and a sponge is great at holding water – as such proper microwaving will clean it thoroughly.
    4) The sponge should be discarded and replaced on a weekly basis.

    If you follow all the steps above the kitchen sponge will be amongst the cleanest item in your house. In fact, I challenge anyone to culture the sponge in my kitchen (with me to over see the collection process and in the lab to assure proper scientific standards are being met) and find more cultures than the water that you drink.

    Let’s bust a real myth. Sponges are safe as long as they are properly maintained.

    • Tammy says:

      So, Mike, help me out. What were the colonies found on their sponge? And what exactly can it cause? I had never heard of either one they showed. I do microwave my sponge daily, and change it sooner than once a week, but there are times when my children use it when I’m not around (and for what God only knows).

      • Not Mike says:

        So I’m not Mike, but I doubt Mike will be back to look at this (or Tammy for that matter, but someone else may stumble on this like I did and wonder :) and I’m not a licensed microbiologist (yet) but I play one on TV….

        I have the episode paused in front of me right now with the “final” list of bacteria genus (aka, “type” of bacteria, not individual species which is more what you are asking I think) found on the sponges. Actually I would bet there are a ton MORE than what they have listed, but they didn’t have room to list them all.

        The biggie nasties they found on the sponges are these five types of bacteria, but note that none of these are really “bad”, most of them you have on you or inside you RIGHT NOW :) It is possible to get an infection from them, but most of the time such infections happen because the person has a weakened immune system. So don’t panic too much. :)

        1. Acinetobacter – This is what they showed as being found on the first sponge they tested, but it is also on their final result. Acinetobacter baumanii is the most commonly cited species, it has been associated with a lot of sickness in veterans returning from Iraq – Wikipedia has more on it and the other bugs if you really care. Just search Wikipedia with the genus names I’m listing. Or, for more medical/illness information you can also search Medscape, they have nice easy summaries of types of infections from these bugs.

        2. Enterobacter – A bacteria that is commonly found in your very own intestines, living a quiet life of retirement and bliss. But it can also cause disease, especially respiratory or urinary tract infections. A common one is Enterobacter cloacae

        3. Klebsiella – Also normal flora, commonly found on our skin and inside us. Again though it can be an opportunistic pathogen like the others – one species of note is Klebsiella pneumoniae which can cause, well, pneumonia.

        4. Pseudomonas – Again, yes, it is a common bug that is usually not harmful but can affect people with weakened immune systems. Pseudomonas aeruginosa is the most common one discussed, and it is EVERYWHERE. On you, on the soil, in the water, you name it. But it can also cause a rather nasty infection if someone does get sick from it, so it’s categorized as a “nasty” like the rest of these. Fun fact: these bugs can fluoresce with a nice yelllow-green color, especially the one named, well, Pseudomonas fluorescens!

        5. Stenotrophomonas – A rather boring bug usually, surprised they are listing it as a “nasty” at all, but the name of one species in the family is rather fun to say three times fast: Stenotrophomonas maltophilia (“malto-” for the suger maltose, which it can metabolize, and “-“-“-philia” which means it not only can metabolize it but it LIKES it! :)

        So there’s the five “nasties” that they decided to list – unless you have HIV though I’m not too concerned about my kitchen sponge potentially having a few of any of these. That being said, though, I do disinfect my sponges in the microwave on a regular basis because there’s no sense in keeping the bugs around either: they’ll just mooch off the free rent, breed, build up resistance from their recliners, and plot new battle tactics together. ;)

  37. MikeA says:

    One more thing the article neglects to mention. All this sponge hysteria has people using rags to clean their dishes. Because they believe rags are safe (since sponges are believed not to be safe) they don’t take care to assure the rag is maintained. As such, the filthy kitchen rag will be far more infectious than a properly maintained kitchen sponge.

  38. Steve says:

    Just saw the rerun of the car skipping. One factual error … The second car was a 1986 Pontiac Fiero GT -a mid-engined, V-6, two-seat car. One of the testers referred to it as a 15-year-old car. Try the math again … In 2009 this is a 23-year-old car.

  39. Ryan says:

    A Pontiac fiero is not a countach! Plain and simple they both have mid engines and that where they stop having anything in common. One is a vey expensive light weight car made of aluminum and fiberglass while they other is steel and other heavy materials. QThey are not the same length as the replica builders know you have to stretch a fiero frame to mount a countach kit kar body. They are not the same width as another modifaction needed for axle length when building replica lamborghini’s. Countach isn’t as tall as a fiero etc etc so therefor in no way is a fiero gonna hit the wind the same way, touch the water the same way, leave the Same wake and so on. Countach also has a aluminum belly pan that makes the entire under side smooth which the fiero does not. Case set before you? The pond skipping was never actually tested and unless someone is prepared to shell out hundreds of thousands to crash lamborghini’s all day it will never be tested. I honestly do not believe it would ever work like the movie no matter how you try so I doubt it would he worth investigating I just hate how the show constantly uses cheap junk cars like tempo’s fiero’s and taurus’s claiming it’s a control test with a common vehicle when those cars are rotting in the junk yards not filling our streets. No one seems to realize that different cars would do you test with conflicting results so unless your going to test vehicle myths with 80 different cars or shelling out the money to use the actual cars in the myth please avoid declaring them plausible or busted. I do love the show It just hurts my brain watching some things on it and my throat is sore from trying to scream at the tv loud enough for you to hear me explain what your doing wrong. Kari I love you!!!!!

  40. Vance A Leland says:

    I definitely want to see a revisit to the lambo skipping across a pond due to the engine placement that tory should have realized while dismantling the small model.

  41. James says:

    Quite happy with the Fiero skipping but would love to see it on a much bigger pond. It skipped once, was about to skip again but they ran out of water. How many skips would they get from the Fiero? 5? 6? Give it max water and find out.

  42. Dheen says:

    I would like to see a revisit to the Lambo skipping the lake but this time why don’t you guys use the rockets from the first episode of Mythbusters the Jaddle Rocket myth .With that type of power and a bigger lake the car might go further

  43. Joe says:

    This experiment should be redone with the correct weight distribution with the motor in the rear like the lambo is in real life so disappointed you guys didn’t notice this mistake before hand I mean really

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