Disinfectants are mixed and do not significantly enhance virus-killing activity
Written by | Ling Jun
Source | "Medical Community" public account
"What if I can't buy alcohol?" "84 Can disinfectant and dishwashing agent kill COVID-19?" "Do I need to dilute?" "How many times should it be diluted?" During the epidemic at home, in the face of a variety of group purchases and express delivery items, how to correctly choose and use disinfectants?
Recently, scientists at the Peter Doherty Institute of Infection and Immunology in Melbourne published a paper in the professional virology journal Virauses entitled "The Efficacy of Ordinary Household Cleaners on the Control of New Coronavirus Infection", which evaluated several commonly used household disinfectants, which not only proved their effectiveness, but also provided scientific laboratory evidence for the effective use concentration of these disinfectants.
Several disinfectants tested include: vinegar, alcohol, household detergents, and bleach.
1
vinegar
Drink vinegar? Steamed vinegar? Spray vinegar?
Whether vinegar can be disinfected, at least in China, is an enduring topic during the epidemic of various infectious diseases.
This trial gave a regrettable result, although vinegar has been shown to inactivate the influenza A virus, but it may be ineffective for the new crown virus.
After using "home-cooked vinegar" to treat the new coronavirus, the researchers found that, whether diluted or not, there was little difference in their effect on the virus within 5 minutes and the control group, "water".
Even if vinegar is replaced with "pure" laboratory acetic acid, the results are not much better, only when the concentration of aqueous acetic acid solution is adjusted to 3.6% v/v, which is equivalent to "household vinegar" dilution to 90%, after 5 minutes can show a slight anti-virus effect.
Researchers therefore caution against vinegar disinfection of items suspected of being contaminated by the coronavirus.
2
alcohol
Alcohol is probably recognized worldwide as the most safe, accessible and effective civilian-grade disinfection product. Previous studies have demonstrated that medical alcohol with ethanol concentrations greater than 60% can effectively inactivate the new crown virus.
The researchers wanted to further explore whether alcohol was effective at lower concentrations, and they further diluted the alcohol solution as low as 10 percent.
The results showed that 50% ethanol solution could be very effective in inactivating the new crown virus in 30 seconds and 5 minutes, but when the concentration dropped below 30%, the phenomenon of the new crown virus killing cells began to appear again.
Therefore, the researchers speculate that 40% of the aqueous ethanol solution can prevent the spread of the new crown virus, but to ensure a safe margin of error, it is recommended that the public dilute to 60%-70% use.
At present, the concentration of ethanol in medical disinfectant alcohol on the market is generally 75%, and the results of this test provide some guidance for those residents who are isolated at home and have run out of alcohol to a certain extent.
3
Household detergent
If you really can't buy alcohol, you may not have to panic, you can first see if there are any types of detergents left at home.
In this trial, the researchers diluted household detergents (such as dishwashing agents) in water and formulated them into solutions of different concentrations, and the results showed that when the detergent concentration was diluted to 0.2%, whether it was 30 seconds or 5 minutes, the new crown virus exposed to it could not detect activity.
However, when diluted 5 times, that is, the concentration is 0.04%, even if it takes 5 minutes, the titer of the new crown virus is not significantly reduced.
The researchers said the assay showed that the detergent still had the effect of inactivating the virus when diluted to 0.2 percent in water, which was equivalent to diluting the original solution to 1/500.
4
bleacher
84 disinfectant is one of the most commonly used household bleaching agents, where the effective chlorine concentration is about 42.6 g/L.
Based on this concentration, the researchers further configured 7 groups of aqueous bleach solutions diluted to 1/50 to 1/1000.
The test found that when diluted to 1/200, the bleach can completely inactivate the virus within 30 seconds, and if the disinfection time is further increased to 5 minutes, dilution to 1/500 can also show anti-virus effect.
Interestingly, the test also tested the active ingredient in the bleach alone, sodium hypochlorite, and found that only 0.84 g/L of sodium hypochlorite solution, equivalent to a bleach solution diluted to 1/50, could show toxic activity at 5 minutes.
The researchers believe this suggests that in addition to sodium hypochlorite, there are other ingredients in household bleach that help kill the new coronavirus.
Mixed use of disinfectants,
It does not significantly enhance the viricidal activity
Given that sometimes combining cleaning products can produce additional antiviral effects, the trial also tested a "strong combination" of bleach and detergents.
The results show:
No cumulative effect was observed, and the combination of bleach and detergent at a minimum effective dose was similar to that of the detergent alone.
No cumulative effect was observed, and the combination of bleach and detergent at a minimum effective dose was similar to that of the detergent alone.
Not only did it not work, but the researchers warned that mixed disinfectants could produce toxic gases that pose a significant health risk to residents.
There are many such examples, such as the mixing of 84 disinfectant with alcohol or toilet cleaner, which may produce highly toxic chlorine gas.
At the same time, although the trial provides guidance on what kind of "COVID-19 disinfectants" residents should choose to buy, it does not further explore the best way to use them. Depending on the disinfectant and the different items required for disinfection, there are also differences in the way it is reasonably used.
For example, alcohol is suitable for wiping and soaking to disinfect, but it is not suitable for spraying in the air. @China Fire Department posted on Weibo on March 23 that alcohol is flammable and explosive, especially in the kitchen, and spraying alcohol carries the risk of explosion or fire.
Intimate clothing is more suitable for soaking with disinfectant and then thoroughly washing, and spraying disinfectant directly may cause health risks.
No matter how diluted the bleach is, it should not be used on utensils, food packaging and other items. When alcohol is not enough, it may be used instead of disinfecting items such as doorknobs, keys, and non-dietary courier boxes.
bibliography:
The Efficacy of Common Household Cleaning Agents for SARS-CoV-2 Infection Control，https://www.mdpi.com/1999-4915/14/4/715/htm
Source: Medical community
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