Researchers at UC Davis found in a mouse study that chemicals commonly found in disinfectant sprays may be more harmful than once thought.
Photo Credit: Towfiqu Barbhuiya
Scientific Frontline: Extended "At a Glance" Summary: Inhaled Quaternary Ammonium Compounds (QACs) Toxicity
The Core Concept: Inhaling common disinfectant chemicals known as quaternary ammonium compounds (QACs) is profoundly more toxic than oral ingestion, causing severe lung injury at exposure levels frequently found in humans.
Key Distinction/Mechanism: Unlike oral or dermal exposure, where QACs do not efficiently penetrate the gut or skin, inhalation via aerosolized sprays provides a direct pathway into the bloodstream. Once inhaled, these compounds cause 100-fold more lung damage and lethality compared to ingestion, largely by impairing mitochondrial energy production within the cells.
Major Frameworks/Components:
- Quaternary Ammonium Compounds (QACs): The primary active chemical agents found in disinfectant sprays, herbicides, mouthwashes, and fabric softeners.
- Mitochondrial Dysfunction: The cellular mechanism of toxicity wherein elevated QAC levels in the bloodstream correlate directly with decreased energy output in cellular mitochondria.
- Inhalation Toxicity Modeling: The application of murine (mouse) models to prove that respiratory exposure to QACs yields blood chemical concentrations mirroring human exposure levels, resulting in acute pulmonary injury.
Branch of Science: Environmental Toxicology, Biochemistry, Pharmacology, and Public Health.
Future Application: These findings are positioned to drive the reevaluation of occupational safety standards and environmental regulations regarding aerosolized cleaning products. The data will likely influence the development of safer, non-volatile disinfection alternatives to prevent chemically induced respiratory damage.
Why It Matters: Given the ubiquitous use of QAC-based disinfectant sprays in domestic and clinical environments, this research highlights a severe public health vulnerability. It suggests that routine airborne exposure may directly contribute to the onset or exacerbation of chronic respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD).
Breathing in common disinfectant chemicals known as quaternary ammonium compounds, or QACs, may be far more harmful than swallowing them, according to a mouse study led by researchers at the University of California, Davis. The study found significant lung injury at blood QAC exposure levels similar to those measured in humans.
The findings raise questions about whether airborne exposure from disinfectant sprays and cleaning products could contribute to respiratory disease such as asthma or chronic obstructive pulmonary disease (COPD). The study was published in Environmental Science and Technology.
“The surprising result of this study was that these compounds, when inhaled, caused 100-fold more lung injury and 100-fold more lethality compared to oral ingestion,” said lead author Gino Cortopassi, a biochemist and pharmacologist with the UC Davis Weill School of Veterinary Medicine.
Widespread use and growing concerns
Quaternary ammonium compounds have been widely used as disinfectants since the 1940s, under trade names Lysol and Roccal. While not very volatile, meaning they don’t make fumes by themselves, they are commonly used in disinfectant sprays, which can enter the lungs. The compounds are also found in some herbicides, eye drop disinfectants, nasal sprays, mouthwash, dryer sheets and fabric softeners.
While it was once thought that these compounds didn’t make it into the bloodstream, in 2021 Cortopassi and colleagues found that 80% of study participants had detectable concentrations of QACs in their blood. They also observed that those participants with highest total QAC levels in their blood had the lowest levels of energy in their mitochondria, the parts of the cells that produce energy. Since QACs do not penetrate the skin or gut well, researchers thought breathing in QACs might explain why the chemicals were showing up in human blood.
Link to human exposure
The new study found when mice breathe in QACs doses at levels that harm their lungs, the amount of these chemicals that ends up in their blood is similar to QAC levels found in human blood. This suggests that breathing in these chemicals — such as from spray cleaners — may be one way they enter the human body.
“We have to question whether we really want to have all of these QAC-based disinfectant sprays in the environment given their proven lung toxicity in mice,” Cortopassi said.
Funding: The study was funded by the National Institutes of Health's National Institute of Environmental Health Sciences.
Published in journal: Environmental Science and Technology
Title: Differential and Sex-Specific Toxicity of Aspirated Quaternary Ammonium Compounds
Authors: Lauren Adcock, Claire B. Montgomery, Sepehr Barkhordari, Sandipan Datta, Laura Van Winkle, Ryan Seguin, Libin Xu, Kyoungmi Kim, and Gino Cortopassi
Source/Credit: University of California, Davis | Amy Quinton
Reference Number: env033026_01
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