What is the minimum amount of chlorine needed for general household sanitation? I usually scrub my kitchen sink with a chlorine bleach cleanser at least 4 or 5 times a week, and wipe down all exposed kitchen surfaces with a weak aqueous solution of Clorox at the same time. I also add Clorox to the rinse water when I am washing the dishes. Unfortunately, many people find the smell of chlorine highly offensive, and some people are also acutely sensitive to it. What is the weakest solution of chlorine that I can use to safely sanitize my kitchen and bathrooms?
I haven’t been able to come up with a definitive answer to this question, because figures vary widely across the board. This is a quote from *Pharmacology in Nursing * by Hahn, Barkin, and Oestreich:
One part of chlorine in 10,000 parts of air causes irritation of the respiratory tract, and exposure to a 1:1000 concentration is fatal after 5 minutes. It causes spasm and pain of the muscles of the larynx and bronchial tubes, coughing, a burning sensation, fainting, unconsciousness, and death. Its extensive use for the purification of water, however, makes it one of the most widely used disinfectants. One part of chlorine in 1 million parts of water will destroy most bacteria in a few minutes. Chlorine is effective against amebas, viruses, organisms of the colon-typhoid group, and many of the spore-forming pathogens.
1 ppm sounds pretty dilute—I’m guessing that would amount to half a teaspoon of Clorox or less in a sink full of water. But here are some other figures: municipal tap water is usually chlorinated to a level of one half of one ppm, or 500 parts per billion. A swimming pool is generally about 3 ppm, and a Jacuzzi is about 10 ppm. All of these levels are tolerable to almost everybody. However, a sanitation engineer who works for the US National Park Service told me several years ago that a chlorination level of 200 ppm is needed to kill hard shelled microorganisms such as cryptosporidium and Giardia lamblia. And the instructions on a bottle of Clorox call for a whopping three fourths of a cup of Clorox per gallon of water for general disinfecting purposes! That must translate to several thousand ppm. :eek:
So what is the most dilute solution that I can effectively use? And does the length of time that the solution stays in contact with the surface alter its effectiveness? Can I get away with a weaker solution if I wipe the surface when the surrounding air is coolest and let the water evaporate naturally?
Bleach 1:100 is very commonly used for disinfection.
With undiluted bleach being a 5% hypochlorite solution (50,000 ppm), 100:1 works out to 0.05% or 500ppm.
I should mention that if it is your intention to do surgery in your kitchen, then you need to look into Phenol-based or gluteraldahyde based disinfectents. (I work as a Sterile Processing Tech in training at a hospital.) Those disinfectants kill EVERYTHING.*
But then those high-power disinfectants are not widly available outside of health care. Here is a website with information on several high-level disinfectants.
I think you should probably spend more effort in overcoming your fear of germs, but then I’m no psychiatrist.
*Including you if you do not use them properly. I have to wear heavy gloves, an isolation gown, a face shield and unimpregnable shoe covers when using the Phenol based disinfectant on the surgical instruments…
Plus, you’ll just start creating an immunity. Although I think the whole “superbugs” thing is more hysteria and less science, it is possible to slowly evolve bacteria and the like so that more and more are resistant to bleach. Or antibiotics, which is where the “superbugs” thing really takes off.
A solution of 1/2 cup each of old-fashion borax and plain old salt in a gallon of water will disinfect just fine and is much less toxic and safer for the environment.
The ratio of bleach to water does not directly translate to the chlorine ratio in the air. That will vary, depending on the water temperature, air movement, air temperature, and the humidity already present in the air. Consider also that Clorox bleach is only 5.25% sodium hypochlorite.
A ratio of 1 part bleach to 10 parts water is the absolute, HIV-contaminated-blood-spill, maximum you ever would need to use. The average home use solution should never be nearly that strong.
Another thing to note: If you mix up your own solution of water and bleach, and then let it sit on your shelf, it will quickly lose potency. You should only make enough for your immediate needs.
This is incorrect. Bleach kills bacteria by ripping their cell walls apart. It’s not something they can easily evolve an immunity to. However, your point stands for antibiotics and antibacterial cleansers.
By contrast, some (many? most? all?) cleaning and hygiene products labeled “antibacterial” contain triclosan and/or triclocarbon, which work by blocking use of a specific enzyme that bacteria need create fatty acids that they need to live. It is possible for a mutation to change the production or use of this enzyme (this has been demonstrated in the lab), so use of these products can encourage the evolution of resistant bacteria. (Cite.)
In short, the old-school disinfectants that rip bacteria apart by brute force are not likely to cause the evolution of resistant strains, but new-fangled antibacterial agents, which targed specific internal processes inside the bacteria, can foster resistance, especially if they are present at low levels, i.e. not enough to quickly kill off all the bacteria that are present.
Sorry to be so picky, asterion, but this is an area of common confusion, and a public heath issue to boot, so I think it’s worth being thorough.
