What Is It?

Quaternary ammonium compounds (often referred to as ‘quats’ or ‘QACs’) denotes a category of ingredients composed of permanently charged ions. They constitute a class of several hundred compounds. Classes of quats include dialkyldimethylammonium compounds (DAD-MACs), alkyltrimethylammonium compounds (ATMACs), and benzalkonium compounds (BACs)[2].

Quats are mostly used as disinfectants (and many are, in fact, registered pesticides with the EPA), but the structure may allow ingredients that wouldn’t otherwise combine to do so in a formulation. By modifying the ingredient’s molecular chains (alkyl chains), different properties result, giving quats the ability to act in products in different capacities, including as antibacterials, surfactants, anti-statics, preservatives, hair conditioning agents, and moisturizers[3].

Why It Matters

Quaternary ammonium compounds, commonly known as quats or QACs, encompasses a large category of chemicals found in various personal care products. The chemicals in this group are widely recognized for their use as disinfectants.

The COVID-19 pandemic resulted in a significant increase in the use of quaternary ammonium compounds due to their prevalence in cleaners recommended by the Environmental Protection Agency (EPA) for their ability to kill bacteria and viruses.

Research on this group of chemicals has also increased in recent years. In one study, the level of quaternary ammonium compounds in household dust was observed to have roughly doubled when compared to pre-COVID levels[1].

Where It’s Found

Ammonium quaternary compounds may be found in disinfectant wipes and sprays, household and industrial/medical cleaners, hand sanitizers, hand soaps, moisturizers, shampoos and conditioners, baby wipes, mouthwashes, and more. Many products contain a mixture of two or more quats.

Found In

Disinfectant wipes and sprays
Household cleaners
Personal care products
Baby wipes
Hand sanitizers
Hand soaps
Mouthwashes

The Health Concern

There are multiple potential routes of exposure to quaternary ammonium compounds. Exposure to quats can occur through inhalation or dermal exposure, depending on a product’s purpose and how it’s applied or used. Ingestion is also a means of exposure to quaternary ammonium compounds, even aside from ingestion during use of a mouthwash containing QACs.

After a surface has been disinfected with a quat-based cleaner (or even utensils or equipment cleaned with quat-based detergents and other products), it can have residues of the compounds, and these residues can ultimately travel to food and become ingested[7].

Similarly, if food packaging contains quats, they can migrate to the food they are in contact with. Some quats, such as benzalkonium chloride, are linked to developmental and reproductive toxicity in mice[8].

Research on quats suggests that two of the most commonly used quats, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyldiemethylammonium chloride (DDAC), may be endocrine active ingredients that impact fertility in mice from ambient exposure[9].

The EPA and European Union also classify ABDAC and DDAC as skin and eye irritants under acute exposures, and some quats are recognized to be skin sensitizers as a result of long-term exposures[7]. A more recent study investigated these two compounds in combination at low, environmentally relevant doses. Synergistically, they exhibited the formation of neural tube birth defects in mice and rats in early gestation and decreases in pup size and survivability in late gestation[10].

Animal studies can be important indicators of potential impacts on humans due to the biological and genetic similarities between humans and mammals. While more research is needed to fully understand the potential harm of quats on humans, specifically, the negative effects seen in the animal data is a cause for concern and a case that further investigation is essential.

Some quats are known to accumulate in human blood[7][11], and thirteen quaternary ammonium compounds have been found in human breast milk, suggesting a plausible pathway for quats to reach infants[2][12]. There are also concerns that quats can give rise to bacteria and viruses resistant to antimicrobials; exposure to high concentrations of quats in an isolated laboratory setting has shown bacterial resistance to quats and antibiotics[13].

Other quats are “formaldehyde releasers” meaning they can release formaldehyde, a known carcinogen[14][15][16], within the formulation.

How to Avoid It

Identifying quaternary ammonium compounds on ingredient labels can be a difficult task, considering they are a large class of chemicals with varying names which may not easily indicate they are a quat compound. To get started, avoid the example quats listed above. To avoid the uncertainty surrounding difficult-to-pronounce ingredients, start here:

Avoid any ingredients with “quaternium” in the name, followed by a number (e.g., quaternium-15)

Avoid any ingredients with “ammonium chloride” in the name or any names ending in “-onium” (e.g., didecyldimethylammonium chloride, benzethonium chloride).

Also avoid any ingredients with “ammonia” or “ammonium” in the name – while these do not always represent quats, it is generally best to avoid all ammonia and ammonium compounds.

Avoid using conventional disinfectants and opt for simple ethanol, hydrogen peroxide, or citric acid-based cleaners when disinfecting surfaces. These are safer active ingredients that are registered with the EPA to be effective against numerous bacteria and pathogens, including SARS-CoV-2.

Be aware that quats are active ingredients in more than 200 disinfectants registered with the EPA to be effective against many bacteria and viruses, making it imperative to read product labels. Wash hands with plain soap and water. This is one of the most important steps you can take to avoid spreading germs and getting sick.