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Classes of Disinfectants: Making the Best Choice by Understanding Regulations, Efficacy, and Methods

By now, most people recognize that proper disinfection is crucial for health and safety. But with so many classes of disinfectants available, it seems like a daunting task to figure out which ones are the best for your facility.

This article outlines the main classes of disinfectants, explains the best methods for using them, discusses their efficacy, and offers a guide for choosing the best disinfectants for your needs. By recognizing the classifications of disinfectants and understanding how disinfectants work, you can effectively protect your facility and staff against infections and the spread of germs.

Recognizing disinfectant classes and their regulations

A chemical germicide, or disinfectant, falls into one of several main categories based on its mode of action, antimicrobial activity, and uses. Whether used alone or in combination, disinfectants contain chemicals that destroy microbes and kill bacteria and viruses. Because some of these chemicals can be harmful if used incorrectly, governments regulate the sale and use of disinfectants.

Classification of disinfectants

According to the Centers for Disease Control and Prevention (CDC), the safest, most effective, and most commonly used disinfectants fall into the classes of chlorine, hydrogen peroxide, and quaternary ammonium compounds. Yet there are many other classes of chemical germicides to consider:

  1. Alcohols (ethyl alcohol or isopropyl alcohol)

Commonly used as an antiseptic and for sterilization of small instruments, alcohol-based disinfectants denature the proteins of bacteria, fungi, and viruses and disrupt their cell walls. However, they are ineffective at killing all germs, don’t destroy bacterial spores, tend to dry and compromise rubber and plastic, and require extended exposure times.

  • Aldehydes (formaldehyde, glutaraldehyde, and ortho-phthalaldehyde)

Aldehydes alter the RNA, DNA, and protein synthesis of harmful microorganisms. They are effective at killing bacterial spores and vegetative bacteria as well as fumigating closed areas and disinfecting medical equipment. However, you must use caution when using these disinfectants—especially formaldehyde—as they contain carcinogenic properties and emit potentially harmful fumes.

  • Halogens or hypochlorites (chlorine, chlorine compounds, chlorine dioxide, and iodine)

An aqueous solution of sodium hypochlorite, otherwise known as household bleach or chlorine bleach, has many modes of action against germs. Chlorine-based disinfectants are affordable, work quickly, and effectively disinfect medical equipment, hard surfaces, and areas with small spills of urine or blood. This makes them ideal for use in health care and food preparation areas. Mouthwashes and antiseptic skin rubs also use chlorhexidine gluconate to treat bacteria.

  • Hydrogen peroxide

Listed by the US Food and Drug Administration (FDA) as an effective disinfecting agent, hydrogen peroxide attacks cell membranes and DNA of bacteria, yeasts, fungi, viruses, and spores. Under normal conditions, hydrogen peroxide disinfectants are stable, safe, and environmentally friendly. A wide range of facilities use these to spot-treat fabrics, small surfaces, and equipment.

  • Phenolics

The antimicrobial activity of disinfectants containing phenol penetrates and disrupts the cell walls of harmful microorganisms. The Environmental Protection Agency (EPA) registers these products for low-level use on environmental surfaces and noncritical medical devices. Phenolics are also effective for precleaning and decontamination before high-level disinfecting.

Many facilities use quaternary ammonium compound disinfectants for environmental, nonmedical surface cleaning of floors, furniture, and walls. The EPA also registers this class of disinfectant as appropriate for use by medical facilities to treat equipment, including those that contact skin.

To determine what class a disinfectant falls under, check the label on each product; the active ingredients listed on the label will tell you which class the disinfectant belongs to. The EPA also provides a convenient chart and a search tool for identifying common disinfectants and their active ingredients.

Regulations for disinfectant manufacturing and use

To ensure disinfectants are both safe and effective, three main government bodies regulate their production and use: the EPA, FDA, and CDC. While the EPA focuses mostly on disinfectants used on environmental surfaces, the FDA regulates those for medical use because they target living tissue. Using scientific evidence, the CDC guides and informs the public about disinfectant use, safety, and efficacy.

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) of the EPA, all substances intended for preventing, exterminating, or repelling any pests, including any microorganism or bacterium, must be registered. This responsibility is that of manufacturers, who must rigorously test the products to safeguard against any harmful effects.

While registering and testing disinfectants are the responsibilities of manufacturers, users have the responsibility of understanding and following all regulation guidelines. The FIFRA requires users to explicitly follow all directions listed on labels and includes a standard statement on all products about proper handling and use. Users who fail to follow directions are subject to enforcement.

Considering factors that affect the efficacy of disinfection and sterilization

When considering the efficacy of disinfectants, it’s important to remember the significant difference between sanitizing and disinfecting. Sanitizing helps keep germs at bay but doesn’t necessarily kill or fully remove germs. Disinfecting is what kills germs and prevents their spread by using a chemical agent and active germicidal ingredients.

Factors that affect the efficacy of disinfection

Although manufacturers design disinfectants to kill germs, many factors affect disinfectant efficacy:

  • Number of germs: The amount of germicide used directly affects how well it works on the microorganisms present in an area or on a surface.
  • Restricted flow: Hard-to-reach areas such as sharp bends, crevices, folds, or corners must contact the disinfectant for proper efficacy.
  • Compatibility: The treatment surface and disinfectant type must be compatible; porous or soft surfaces require different types of disinfectant than nonporous, hard surfaces.
  • Method of application: Whether you spray, wipe, or scrub affects the contact time of disinfectants as does the amount of surface water present.
  • Resistance of germs and potency of disinfectant: Highly resistant microorganisms require stronger potency or higher concentrations of chemicals.
  • Physical and chemical factors: Temperature, humidity, and pH all affect the performance of disinfectants.
  • Organic vs. inorganic matter: Some disinfectants do not work well in the presence of organic matter such as blood, urine, or lubricants.

The labels on disinfectants provide detailed information about best use for effectiveness. Read all labels carefully to be sure the one you choose is most efficient for your needs.

Levels of disinfectant effectiveness

In addition to understanding the factors that impact efficacy, consider the varying levels of disinfection:

  1. A low-level disinfectant treats noncritical items and surfaces, including intact skin, shared devices, and common areas, such as waiting rooms. Disinfectant wipes and quaternary ammonium compounds are examples of low-level, common disinfectants.
  2. An intermediate-level disinfectant treats both critical and noncritical items such as clothing and operatory surfaces. Common types of intermediate-level disinfectants are quats, sodium hypochlorite bleaches, and hydrogen peroxide–bleach hybrids.
  3. A high-level disinfectant treats semicritical and critical items that contact open skin or wounds. Examples of a high-level disinfectant are peracetic acid, hydrogen peroxide, glutaraldehyde, and ortho-phthalaldehyde classes. These products can include potentially harmful ingredients if not handled correctly, so they require handling by trained health care workers.

Each level of disinfection requires specific procedures for use and exposure time, and each depends upon the type of surface or item being treated. The CDC provides a detailed chart for each level and class. If you follow these recommendations and those on the labels, you’ll increase disinfectant efficacy.

The importance of exposure time

Length of exposure plays a distinct role in the efficacy ofa chemical disinfectant for disinfection and sterilization. A germicide must contact a surface long enough for the active ingredient(s) to complete a sterilization cycle by either destroying the structure of infectious microorganisms or compromising their reproductive capabilities. The longer the exposure time, the higher the probability of completing the sterilization process.

Alcohol-based disinfectants represent a good example of why germicide exposure time matters. Even when mixed with water, alcohol evaporates quickly. With less time adhering to surfaces, disinfectants in this class cannot properly break down the proteins of bacteria. Consequently, they are ineffective at killing bacterial spores and treating organic matter such as blood.

Every disinfectant has a recommended exposure time based on thorough testing by manufacturers and successful registration with the EPA. While one disinfectant solution may need thirty minutes to kill bacteria, another may need three hours. Check labels for recommended exposure time.

Determining which disinfectant to use and the methods for using it

Methods for disinfection depend on many factors, including surface type, chemicals used, exposure time, and potency. Regardless of which disinfectant you use, always start by cleaning and sanitizing surfaces and spaces before disinfecting. Dirt, grime, grease, or debris can block chemicals from penetrating surfaces.

What are common methods of disinfection?

Some products must be mixed with water, while others are diluted disinfectants and ready to apply. Some are better for spraying, while others are better for wiping or rubbing. Always check the labels for proper use. The CDC provides detailed information regarding disinfection methods for each class of disinfectant.

To ensure proper disinfection methods, follow these general guidelines:

  1. Develop a plan by determining what needs to be cleaned and what resources you need.
  2. Protect yourself and others by wearing PPE and properly training staff.
  3. Thoroughly read and follow all instructions on product labels.
  4. Wash your hands before and after disinfecting.
  5. Choose safe and nonallergenic disinfectants; check the EPA List N.
  6. For soft surfaces, laundry, electronics, and outdoor areas, use alternative methods such as applying hot water and soap or using wipeable covers.

How do you determine the proper disinfectant for your work environment?

When comparing different disinfectants, first consider the types of germs you need to treat. Then consider efficacy, safety, and ease of use:

  • Types of germs and their characteristics: Do you need to target bacteria, viruses, or fungi? Is the pathogen known to have high resistance? Which type(s) of germs does the product target? Be sure to choose one with the right active ingredients. Products listed as broad-spectrum disinfectants are a good choice because they are effective against both gram-positive and gram-negative bacteria, such as Staphylococcus aureus and Salmonella enterica, respectively.
  • Safety: Will people or animals have close or long-term exposure to the chemicals in the disinfectant? Are any of the chemicals in the product known to cause allergic reactions? Does the product stain, is it corrosive, or does it have a nasty odor? Check the labels, and opt for disinfectants labeled as safe for human and animal exposure.
  • Ease of use: Is the disinfectant solution ready to use, or does it require mixing, dilution, or repeated applications? How often do you need to disinfect? Does the recommended application method work for your needs? Check how quickly the disinfectant kills a specific pathogen and how long the items or surfaces need to be exposed.

Staying safe and healthy by using disinfectants

With the variety of classes of disinfectants available, understanding how each functions can help you make the best decision for preventing the spread of germs in your facility. If you read labels, follow regulations, and practice best methods, you’ll play a significant role in keeping everyone safe and healthy.

Visit Spruce Industries to learn more about the surface-cleaning products we offer or ask us questions about what products are right for your business.

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