Update: Hand sanitizers (with at least 60% alcohol content) are effective at killing SARS-CoV-2. However, they should not be consumed. There has been a 79% in U.S. poison control calls related to children unintentionally consuming hand sanitizer. Remember to keep these products away from children!
We have all seen disinfecting agents in sparse supply at retail outlets. Given that disinfecting agents have powerful active ingredients, we need to know when and how to use them to avoid trading infectious disease for known (disinfecting) poison. This impacts our home health and indoor air quality because these compounds persist on surfaces and in our air for anywhere from minutes to months!
Why does it matter if we inhale these compounds? Many of the constituents of disinfectants can be absorbed from the lungs into the bloodstream and be distributed to the rest of the body. Think of anesthetic gases: we inhale them and they reach our brains for us to fall asleep! A less positive example: smoking cigarettes increases the risk of bladder cancer from constituents that we believe are absorbed in the lungs that ultimately reach the bladder.
First: why disinfect? If you’re staying home and not bringing any virus into the house (ie you are correctly sheltering in place), you don’t need to routinely disinfect surfaces in your house UNLESS there is a sick member in the household. If someone is sick, disinfecting high-traffic areas (such as bathrooms, kitchen, shared spaces, etc.) is incredibly important, among other safety measures (discussed in previous posts).
Even if you are correctly sheltering in place, you may still leave the house for essential functions, or you may consider disinfecting any delivered goods, even if you don’t leave the house. These are also appropriate times to consider using disinfecting products.
Next: how do we safely disinfect surfaces that may harbor virus? To best answer this question, let us define several criteria:
- Effectiveness of disinfecting agent at destroying SARS-CoV-2
- Appropriateness of disinfecting agents for the intended surface
- Toxicity of the disinfecting agent to humans and the environment
- Toxicity of inactive ingredients in the disinfecting agent to humans and the environment
- Safety of the disinfecting agent where it may contact humans (skin, nose, eyes, lungs, etc.)
- Potential of the disinfecting agent to linger in the environment (air, surfaces, etc.)
- Practicality: minimizing anxiety from balance of infectious risk and toxicities
Using this framework we can try to navigate the very complicated waters of safe home cleaning.
The easiest answer is to use soap and water: it is effective, safe, and does not linger appreciably in the environment. Of course, the soap you use must not contain inactive ingredients that may be toxic! For example, fragrances are a common inactive ingredient to avoid.
Given that soap and water may not be appropriate for every surface, there are innumerable other products available for disinfecting. Let’s go through them using our criteria from above.
We are still learning about what chemicals will inactivate SARS-CoV-2, but fortunately we know that coronaviruses are readily destroyed by many chemicals. The EPA has provided general guidance for what we suspect will be effective in destroying SARS-CoV-2 (see reference below). To summarize:
- Sodium hypochlorite (“bleach”): effective
- Quaternary ammonium (“QUAT”): effective
- Alcohol (>60% concentration); ethanol or isopropanol: effective
- Hydrogen peroxide (0.5% concentration): effective
- Benzalkonium chloride (a particular quaternary ammonium): suspected less effective (based off SARS and MERS data)
- Chlorhexidine digluconate: suspected less effective (based off SARS and MERS)
- Vinegar: NOT EFFECTIVE
Kampf, Günter, et al. “Persistence of coronaviruses on inanimate surfaces and its inactivation with biocidal agents.” Journal of Hospital Infection (2020).
Appropriateness for the intended surface
Certain agents may destroy particular surfaces (paint, plastics, leather, silk). Perhaps not a direct health concern, but important to consider.
Toxicity of the disinfecting agent
This is a significant topic, and we must recognize that many concerns are vague because it is difficult and unethical to perform randomized clinical trials of products suspected to be highly toxic yet ubiquitous in our environments. To summarize: we can characterize side effects easily surmised (skin and eye irritation) but more severe toxicities are rarely well studied and likely remain unknown. In fact, one of the few ways we know severe side effects is from catastrophic historical occupational accidents. To summarize what we do know:
- Sodium hypochlorite (“bleach”): severe eye, skin, lung irritation; question of chlorine resulting in decreased smell/taste (!)
- Quaternary ammonium: severe skin and lung irritation; association with asthma
- Alcohol-based: likely safer than above
- Hydrogen peroxide: likely safer than above
- Benzalkonium chloride: concerns for carcinogenicity
- Many of these disinfecting agents have potential side effects including the development of cancer and hormonal disruption. As stated above, it is very difficult to prove these toxic side effects because randomized clinical trials would be unethical to perform!
- Bleach should never be mixed with acid because of the development of chlorine gas (highly toxic). Don’t mix with anything other than water!
- There is concern for changes in smell and taste sensation related to chlorine exposure. This has been reported in occupations that heavily rely on disinfecting agents, as well as in swimmers and pool cleaners. As stated above, it is very difficult to systematically test for this toxicity, but given the importance of smell and taste for the pleasures of life (and to warn of smoke, gas leaks, or rotting food!), I personally am very conservative about protecting these senses! I recommend we all take these (however rare) reports seriously.
Take home: try to opt for alcohol- and hydrogen peroxide- based disinfectants.
Kim, Hyun Joo. “Two cases of anosmia suspected to be caused by chronic chlorine exposure in cleansing works.” Korean Journal of Occupational and Environmental Medicine 17.2 (2005): 155-159.
Toxicity of inactive ingredients
Many inactive ingredients are added to our disinfectants, such as for fragrance (parfum) or ease of application (aerosol cans). Unfortunately, these may not be fully listed under a product’s ingredients, or they may be hidden under a “proprietary” listing. Inactive ingredients can pose significant harm to our bodies and our environments. UCSF has provided an easy to read list (not exhaustive) of inactive (and some active) ingredients to avoid when possible, which includes:
- 2-butoxyethanol (or ethylene glycol monobutyl ether) and other glycol ethers
- Alkylphenol ethoxylates (some common ones are: nonylphenol and octylphenol ethoxylates, or octoxynols)
- Bisphenol A
- Dyes (may be listed as FD&C or D&C)
- Ethanolamines (common ones to look out for are: monoethanolamine [MEA], diethanolamine [DEA], and triethanolamine [TEA])
- Pine or citrus oil
- Quaternary ammonium compounds (look out for these: alkyl dimethyl benzyl ammonium chloride (ADBAC), benzalkonium chloride, dodecyl-dimethylbenzyl ammonium chloride; lauryl dimethyl benzyl ammonium chloride; benzyl-C10-16- alkyldimethyl, chlorides; benzyl-C12-16-alkyldimethyl, chlorides; benzyl-C12-18-alkyldimethyl, chlorides; benzyl-C16-18-alkyldimethyl, chlorides; and didecyl and didecyl dimethyl benzyl ammonium chloride)
- Triclocarban and Triclosan
- Bleach or sodium hypochlorite
Note that benzalkonium chloride (the active ingredient in many Lysol products) is still awaiting a formal safety review by the FDA, despite being readily available over-the-counter.
I want to point out that “fragrances” and “parfum” sound innocuous, but may pose serious health risk, and should be avoided whenever possible. Take home: always try to purchase unscented cleaning items, largely to avoid the inclusion of “fragrances”.
Safety of where disinfectants contact humans
We may come in contact with disinfectants across our:
- Skin (wear gloves)
- Eyes (wear protective eyewear)
- Lungs (open all windows to ensure maximal ventilation, avoid aerosol cans that spray small particles that can potentially travel deep in our lungs)
- Mouths (children placing the disinfected objects in their mouths: rinse any cleaned toys with soap/water)
It is important to remember that many compounds can readily pass through our skin and lungs to enter our bloodstream and be distributed to the rest of our bodies. As a simple example, think of anesthetic gases that we inhale that reach our brains to put us to sleep! Everything else we inhale in our environment similarly has the potential to reach our brains and the rest of our bodies.
I also want to point out that we should not be using aerosol sprays if at all possible because the very small particle size allows these contents to both linger in the environment (air) and travel deeply into our bodies (theoretically reaching deeper parts of our lungs where they may cause more damage). Furthermore, additional inactive compounds may be added to aerosols to facilitate the active ingredient being aerosolized from the can (butane, etc.). This problem can easily be avoided by using pump sprays instead of aerosol sprays.
Aerosolized materials may linger far longer suspended in the air, as well, as they are not as heavy as water droplets that readily fall to the ground. This only works to prolong our exposure to them in our lung tissue.
Lastly, do not forget that these disinfecting agents should generally not be used on our skin or on the fur of our pets! Soap and water is the way to go for cleaning ourselves whenever possible (exception: hand sanitizer can be valuable at the grocery store).
Take home: Avoid aerosols and opt for pump sprays instead. Try to always wear gloves, protective eyewear, and open all windows to ensure maximal ventilation whenever using disinfecting products. Be sure to wipe any disinfected surfaces with soap and water, particularly if they may come in contact with childrens’ mouths!
How long disinfecting agents persist in our environments
Practical considerations are how long the disinfecting agent remains suspended in the air (where we may inhale it and have it potentially travel deep into our lungs) and how long compounds remain on surfaces that we disinfect.
Aerosols can remain in the air for a long period of time: think of spraying Lysol in the air and how long you can still smell the sent for!
With regards to compounds that remain on hard surfaces (whether sprayed or wiped): there are far too many compounds to summarize here. The practical approach is to wipe down any disinfected surfaces with soap and water, particularly if they may come in contact with children!
Take home: avoid aerosol cans and wipe down any disinfected surfaces with soap and water to remove potentially toxic compounds.
Minimizing anxiety and practical take-home
This covered a lot of information, and I’ve summarized the take-home messages in each section. Creating an “action plan” about how to approach disinfecting during this pandemic can significantly help reduce the burden of anxiety. Remember: incomplete data instigates anxiety and stress because our brains naturally love to plan for the future (which we cannot do with incomplete information). Also keep in mind that single/one-time exposures are different than continuous/occupational exposures: the general principle in medicine is that effects are dose-dependent (not always but usually).
Having general guidelines that we can solidly fall back on can help us navigate through this challenging time:
- If no one is sick at home, and nobody is leaving or entering the house, surfaces generally do not need to routinely be disinfected
- Never discount the power of soap and water
- Always seek out unscented products (avoid anything with fragrance or parfum)
- Try to opt for alcohol- and hydrogen peroxide-based active ingredient disinfectants (versus bleach- and quaternary ammonium-based)
- Vinegar is not effective against COVID-19
- Avoid aerosol cans and opt for pump spray bottles
- Always open windows to maximize ventilation when using disinfecting products (and keep open!). If you can still smell the product in the air, it may be reaching deep in your lungs and the rest of your body!
- Wear gloves and protective eyewear
- Try to wipe down any disinfected surfaces with soap and water when possible, especially if it will come in contact with children!
- If a less-than-optimal cleaner is used (particularly in the setting of product shortages like we have currently) remember that one-time exposures are typically far less consequential than persistent exposures (“dose-dependence”): don’t let anxiety from a less-than-ideal product get the better of you in this challenging time (if only used for a short duration!)
While there is so much information about disinfecting products, your peace of mind is critical to protect! A stressed and weakened immune system doesn’t do you any favors!