Germs Away!

Out of disinfectant wipes? Many people are struggling to find disinfectant wipes in stock. The shortage is terrible timing for the current wave of COVID-19 cases overwhelming the world. With the coronavirus running rampant yet again, it is important to keep surfaces clean to avoid transmitting the virus. Even though the virus isn’t likely spread through physical contact, it doesn’t hurt to be safe. But how do disinfectants kill bacteria and viruses?

Before we discuss that, let’s go over what a disinfectant actually is. Subtle differences exist between cleaners, sanitizers, disinfectants, virucides, and sterilants:

Cleaners

Cleaners help eliminate germs from a surface. Soap is an example of a cleaner; soap assists water in removing any germs from your hands.

Sanitizer

Sanitizer reduces the number of bacteria on a surface. Hand sanitizer is aptly named—it doesn’t kill every single bacterial being on your hands.

Disinfectant

Disinfectant destroys bacteria (but not their spores), viruses, and fungi on hard surfaces. Most Lysol and Clorox products are considered disinfectants by the Environmental Protection Agency (EPA). There are different levels and types of disinfectants, but we won’t go into that.

Virucide

Virucide either terminates viruses or renders them inactive. Some bleaches are considered virucidal, but it depends on the manufacturer.

Sterilant

Sterilant eradicates all microorganisms, including fungi, viruses, and all forms of bacteria and their spores. Sterilants are less common in everyday use; with the correct concentrations and contact periods, hydrogen peroxide can work as a sterilant.

As the agents become more effective against microbial life, they also grow more dangerous. Consequently, it is imperative to read the directions and warnings before using these products. Although disinfectant wipes are convenient and generally safer to use, their effectiveness depends on what they are made of and how they are used.

Fun Fact: Mycobacterium tuberculosis, which causes tuberculosis, is one of the most resistive microorganisms, so if a disinfectant is tuberculocidal (meaning it can kill Mycobacterium tuberculosis), it is effective against most pathogens because we can assume that the disinfectant can eliminate any other microorganisms of lower resistance.

The EPA keeps track of all disinfectants. Depending on the active ingredient(s), each disinfectant is effective against a specific microorganism or group of microorganisms. Disinfectants need the surface to stay wet for some time to kill off the pathogens—this is called the dwell time or contact time. It is also critical to note that some disinfectants can be harmful to certain surfaces. Here is EPA’s list of disinfectants effective against SARS-CoV-2: List N Tool: COVID-19 Disinfectants | US EPA. EPA registration numbers are found on the product packaging, typically on the back in small font. Below the picture of the EPA registration number is the corresponding search result in EPA's list of COVID-19 disinfectants.

Different disinfectants use different chemical agents to impair the pathogens’ cells; most of them work best at a certain concentration. Let’s take a lot at some common types of disinfectants:

Hydrogen Peroxide

You might have used hydrogen peroxide before to prevent infection in your cuts and scrapes. By forming “destructive hydroxyl free radicals,” this compound targets key cell constituents such as membrane lipids and DNA. 3% is a standard concentration for hydrogen peroxide as an antiseptic. However, using hydrogen peroxide for skin wounds is no longer advised because this compound can be dangerous at high concentrations and/or large amounts, ingested or touched. Scientists have been exploring its potential to be a sterilant at higher concentrations (6%-25%).

Chlorine

Ever heard of bleach? Household bleach uses about a 5-6% concentration of sodium hypochlorite, which is a chlorine compound. Through oxidation, chlorine compounds attack vital metabolic enzymes. When using bleach, remember that it can be very harmful if used incorrectly. Never mix chlorine bleach with ammonia or vinegar—those combinations can form chlorine gas, which is poisonous. Don’t combine chlorine bleach with anything—just to be safe.

Fun Fact: If you've bleached your hair before, you may have used one of the following: chlorine bleach (sodium hypochlorite), oxygen bleach (hydrogen peroxide—not a chlorine compound), or bleaching powder (calcium hypochlorite). These agents sever the chemical bonds of the chromophores (the molecules responsible for color), causing them to lose their color.

Quaternary Ammonium Compounds

Nicknamed “quats,” quaternary ammonium compounds are widely used as disinfectants. In fact, the active ingredient of Clorox disinfecting wipes is a quaternary ammonium compound. The primary effect of these compounds is the denaturation of essential proteins. Denaturation forces a protein to revert back to its primary structure, rendering it useless.

Alcohol

Alcohols are used to disinfect various surfaces by denaturing proteins. Isopropyl alcohol, more commonly known as rubbing alcohol, is typically applied to the skin before a medical shot to disinfect that patch of skin. However, it is not advised to apply rubbing alcohol on an open wound since it could cause further damage. Because they are not the most potent disinfectants, alcohols aren’t utilized as much as other disinfectants to clean medical instruments. Their inability to eliminate bacterial spores prevents them from being ranked higher than an intermediate-level disinfectant. Alcohols are most effective at 60-90% concentrations because they require a certain portion of water to work effectively.

Fun Fact: CDC recommends using alcohols of at least 70% concentration to combat the SARS-CoV-2 virus.

Now that you’ve learned the magic of disinfection, make sure you stay safe out there! It is crucial to clean—not disinfect!—your hands and disinfect surfaces, especially during a pandemic. I hope you learned something new today! Keep a lookout for the next post!