Disinfectants: A Guide to Killing Germs and What Dangers to Be Aware Of

Person wearing gloves and spraying down a counter

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From drug-resistant bacteria to flu outbreaks and COVID-19, health scares dominates the news these days. In response, you may go searching for products that claim to eradicate bacteria, viruses and other germs.

Not all of these disinfectants are effective against every type of bacteria or bug, however. And although we may think these products are keeping us healthy, the truth is some may be harmful to both our health and the environment.

To help you choose the right disinfectant, we’ve provided how-to information for a variety of germ-busting agents. We've also added notes about the novel coronavirus SARS-CoV-2, which causes the disease known as COVID-19, as well any dangers to avoid.

This coronavirus seems to spread most commonly from person to person via respiratory droplets, according to the U.S. Centers for Disease Control and Prevention (CDC), usually between people who are within about 6 feet (1.8 meters) of each other. Transmission of the virus from contaminated surfaces has not yet been documented, the CDC notes, but current evidence does suggest the virus can remain viable "for hours to days on surfaces made from a variety of materials."

To disinfect surfaces, the CDC recommends a household bleach or alcohol solution (see below for details), and points to a list of disinfectant products registered by the U.S. Environmental Protection Agency (EPA) that have qualified for use against the novel coronavirus. Washing with soap or water is the best way to rid the virus from your hands, the agency adds, but if soap and water aren't available, an alcohol-based hand sanitizer with at least 60% alcohol may be used.

Bleach

Bleach is a relatively cheap and highly effective disinfectant. It kills some of the most dangerous bacteria, including staphylococcus, streptococcus, E. coli and salmonella — as well as many viruses, including the flu and the common cold. It should also work on the novel coronavirus, according to the CDC, which notes that "unexpired household bleach will be effective against coronaviruses when properly diluted."

In its guidance for COVID-19, the CDC advises using a bleach solution with 5 tablespoons (1/3 cup) bleach per gallon of water, or 4 teaspoons bleach per quart of water, and following manufacturer's instructions for application and ventilation.

What are the dangers?

While bleach can be an important disinfectant in some situations, it's also a potential hazard to human health, capable of not only irritating sensitive tissue in the eyes, skin, mouth and throat, but also contributing to long-term respiratory problems like asthma. Bleach can also be hazardous to pets, wildlife and ecological health. There are some safer alternatives in disinfecting wipes and cleaning sprays, although these eco-friendly choices may not be as effective in killing bacteria and viruses. Bleach and bleach alternatives should never be used on the skin.

Very importantly, bleach should never be combined with ammonia or vinegar. Mixing bleach and vinegar releases a toxic chlorine gas, reports Thought Co. Similarly, mixing bleach with ammonia or ammonia-based products produces extremely dangerous toxic vapors.

Soap and water

man washing hands
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Regular soap and water clean germs away rather than killing them, but that's still a key step in reducing infection, the CDC points out. Washing your hands with soap and water is one of the main recommendations for limiting the spread of the novel coronavirus, since it seems to spread primarily from person to person via respiratory droplets, which are often found on our hands and easily transferred to our faces.

What are the dangers?

Store shelves are also filled with products that boast antimicrobial properties, including antibacterial soap. There is a common misconception, however, that antibacterial soap is effective in eradicating all germs. Although antibacterial soap may kill some bacteria, there is little evidence that it's more effective than regular soap, and it offers no additional protection from viruses.

In fact, many health experts advise against using antibacterial products, as many contain a potentially harmful ingredient called triclosan, which some research suggests is an endocrine disrupter. Moreover, overuse of these products may contribute to antibiotic resistance and the rise of so-called superbugs.

Ammonia-based cleaners

Although it may be a more environmentally friendly cleaning solution than many other products, ammonia is not registered as a disinfectant by the EPA. Ammonia might kill salmonella and E. coli, but it is not an effective defense against dangerous staphylococcus bacteria.

What are the dangers?

A noted above, ammonia is highly dangerous when mixed with bleach.

Alcohol-based hand sanitizers

bottle of hand sanitizer with pump
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Alcohol has long been used as an antiseptic. Ethyl alcohol in particular is effective against a wide range of bacteria, and also some viruses, namely those known as "enveloped viruses." These viruses — including influenza and coronaviruses — are enveloped in a lipid membrane that can be disrupted by alcohol and other disinfectants, thus inactivating the virus. Alcohol may not be helpful, however, against viruses that lack this envelope, such as norovirus.

For disinfecting surfaces, the CDC advises using an alcohol solution with at least 70% alcohol. For hand sanitizers, it suggests using one with at least 60% alcohol, although it notes washing your hands with soap and water is preferable. The U.S. Food and Drug Administration (FDA) has warned the makers of some hand sanitizers against claiming their products can prevent infections like the flu, citing inadequate evidence. If you buy hand sanitizer, avoid products that contain triclosan. As an alternative to buying it, you could also make your own hand sanitizer at home.

What are the dangers?

Keep hand sanitizer away from small children. Because most sanitizers contain such a high amount of alcohol, swallowing even a little bit can lead to alcohol poisoning. The CDC reported a recent case where a preschooler was rushed to the hospital after drinking hand sanitizer that was left out on the kitchen table. Her blood alcohol level was 273 mg/dL (most state laws define drunk driving as 80 mg/dL). She spent 48 hours recovering in intensive care.

Vinegar

Vinegar can be used as a safer bleach alternative for some applications, such as cleaning, and research has shown it can be effective against some bacteria and viruses, including the flu. It is also biodegradable. Vinegar is not a registered disinfectant, however, and does not kill dangerous bacteria like staphylococcus.

What are the dangers?

As noted above, vinegar is highly dangerous if mixed with bleach.

Disinfectant products

There are dozens of sprays, cleaners and wipes sold to clean and disinfectant various areas of the home. The EPA offers an extensive list of disinfectant products that meets its criteria to combat SARS-CoV-2. The EPA says to make sure to follow the recommended contact time, which is the amount of time the product should remain on a surface before being wiped away.

What are the dangers?

Never combine products and never use them in any way other than as directed on the label. In late April, there were some misleading suggestions about how disinfectants might be used to combat COVID-19. The makers of Lysol responded with a statement saying, "As a global leader in health and hygiene products, we must be clear that under no circumstance should our disinfectant products be administered into the human body (through injection, ingestion, or any other route). As with all products, our disinfectant and hygiene products should only be used as intended and in line with usage guidelines. Please read the label and safety information."

Hydrogen peroxide

Hydrogen peroxide has antimicrobial properties and can be an effective household cleaner. It is also highly biodegradable.

What are the dangers?

Concentrated hydrogen peroxide is extremely dangerous and should only be used as a disinfectant at concentrations lower than 3%.

Baking soda

Although baking soda is often used a household cleaner, it is ineffective against most bacteria, including salmonella, E. coli. and staphylococcus. If you suspect there has been a contamination of any of these bacteria, ditch the baking soda in favor of a product registered as a disinfectant by the EPA.

What are the dangers?

Baking soda can be dangerous if swallowed in large amounts. It may cause irritation and redness if it gets into your eyes, reports The Spruce.

Tea tree oil

Tea tree oil is a natural, biodegradable antiseptic that can be useful for treating minor cuts and wounds. It may not be strong enough to kill viruses and more powerful bacteria, though.

What are the dangers?

Tea tree oil is poisonous if swallowed. It should not be used anywhere near the mouth.