UZH Professor Akdis: 'The effect that we found could mark the beginning of the destruction of the gut’s epithelial layer'

A study conducted by researchers with the Swiss Institute of Allergy and Asthma Research (SIAF), an associate of the University of Zurich (UZH), found that a common ingredient in the commercial rinse agents used in professional-grade dishwashers can negatively impact the gastrointestinal tract, according to a UZH News article.

During a typical commercial dishwasher cycle, hot water and detergent are circulated at high pressure for approximately 60 seconds. This is followed by a second minute-long washing and drying cycle in which water and a rinse agent are applied.

“What’s especially alarming is that in many appliances, there’s no additional wash cycle to remove the remaining rinse aid,” said study leader Cezmi Akdis, who is also a UZH professor of experimental allergology and immunology and director of the SIAF. “This means that potentially toxic substances remain on the dishes, where they then dry in place.”

When the dishes are reused, the dried chemical residue can end up in the gastrointestinal tract.

Inspired by these concerns, Akdis' team began investigating the impact of commercial-grade detergents and rinse agents on the gut's epithelial barrier, or the layer of cells that lines the intestinal tract and controls what enters the body. A barrier defect is associated with multiple health conditions including the following: food allergies, gastritis, diabetes, obesity, cirrhosis of the liver, rheumatoid arthritis, multiple sclerosis, autism spectrum disorders, chronic depression, and Alzheimer’s disease.

Similar protective layers also exist in the skin and lungs. Numerous studies have found that additives and chemicals found during daily life can harm these barriers, the article said.

“We assume that defective epithelial barriers play a role in triggering the onset of two billion chronic illnesses,” said Akdis.

The connection is explained by the epithelial barrier hypothesis, which Akdis helped to develop during his 20-plus years of research in his field.

As a part of their study, the researchers used a newly developed technology: microchips carrying human intestinal organoids and intestinal cells. They also used multiple biomolecular methods to analyze commercial detergents' effect on the cells. They then diluted the substances to reflect the amounts that would usually be present on dry dishes (1:10,000 to 1:40,000).

The researchers found that high doses of rinse agents killed the intestinal epithelial cells and lower doses made them more porous. The team also observed the activation of several genes and cell signaling proteins that could trigger inflammatory responses. Further analysis revealed that alcohol ethoxylates, one component of the rinse agent, were responsible for the reaction.

“The effect that we found could mark the beginning of the destruction of the gut’s epithelial layer and trigger the onset of many chronic diseases,” Akdis said. “It is important to inform the public about this risk, since alcohol ethoxylates seem to be commonly used in commercial dishwashers.”