Researchers discover incredible link between dishwashers and chronic illnesses
[June 14, 2023: Cezmi A. Akdis, University of Zurich]
Residue from rinse agents is left behind on dishes after they are cleaned in professional-grade dishwashers. (CREDIT: Creative Commons)
A new study by researchers at the Swiss Institute of Allergy and Asthma Research (SIAF), an associated institute of the University of Zurich (UZH), has revealed the toxic effect of one ingredient in commercial rinse agents on the gastrointestinal tract. The study’s findings have implications for public health, as the toxic substance could trigger the onset of many chronic diseases.
Commercial dishwashers are widely used in various settings, from restaurants to barracks, to wash plates, glasses, and cutlery. A typical cycle in these machines involves circulating hot water and detergent for around 60 seconds at high pressure. In the second 60-second washing and drying cycle, water and a rinse agent are applied.
The study discovered that many appliances do not have an additional wash cycle to remove the remaining rinse aid, allowing potentially toxic substances to remain on the dishes, where they then dry in place. When these dishes are used again, the dried chemical residue can easily end up in the gastrointestinal tract.
The research team under Cezmi Akdis, UZH professor of experimental allergology and immunology and director of SIAF, investigated the effect of the components of commercial-grade detergents and rinse agents on the epithelial barrier in the gut.
The epithelial barrier is the layer of cells that lines the intestinal tract and controls what enters the body. A defect in this barrier is associated with conditions such as food allergies, gastritis, diabetes, obesity, cirrhosis of the liver, rheumatoid arthritis, multiple sclerosis, autism spectrum disorders, chronic depression, and Alzheimer’s disease.
To conduct the study, the researchers used human intestinal organoids and intestinal cells on microchips, a newly developed technology. The tissue forms a three-dimensional clump of cells that is very similar to the intestinal epithelium in humans.
The team used various biomolecular methods to analyze the effect that commercial detergents and rinse aids have on these cells. They diluted these substances to reflect the amounts that would be present on dry dishes (1:10,000 to 1:40,000).
Dose-dependent cytotoxicity in Caco-2 cells in response to professional dishwasher detergent and rinse aid. A, Cytotoxicity of monolayer-cultured Caco-2 cells treated with professional dishwasher detergent and rinse aid alone or as a mixture for 24 hours in different dilutions. (CREDIT: The Journal of Allergy and Clinical Immunology)
The study found that high doses of rinse agents killed the intestinal epithelial cells, and lower doses made it more permeable. Researchers also observed the activation of several genes and cell signaling proteins that could trigger inflammatory responses. A more detailed analysis showed that one component of the rinse agent – alcohol ethoxylates – was responsible for this reaction.
The researchers warn that the effect they found could mark the beginning of the destruction of the gut’s epithelial layer and trigger the onset of many chronic diseases. Akdis calls for an immediate response: “It is important to inform the public about this risk, since alcohol ethoxylates seem to be commonly used in commercial dishwashers.”
The rinse aid decreased TEER and increased PF in differentiated Caco-2 cells. A, C, and E, TEER was measured every 24 hours for 9 days for cells treated with detergent and rinse aid alone or as a mixture. B, D, and F, PF was measured in response to 72 hours of exposure to the detergent and rinse aid alone or as a mixture. (CREDIT: The Journal of Allergy and Clinical Immunology)
The connection between defective epithelial barriers and chronic illnesses has been explored in numerous studies. As Akdis explains, many additives and chemicals that we encounter in everyday life can damage these layers.
“We assume that defective epithelial barriers play a role in triggering the onset of two billion chronic illnesses,” he says. This connection is explained by the epithelial barrier hypothesis, which Akdis has helped develop during his more than 20 years of research in this field.
Rinse aid alters mRNA expression of major TJ and AJ genes. A and B, Genes that are significantly changed in response to rinse aid vs unexposed (log2 ratio). ∗P < .05. ∗∗P < .01. ∗∗∗P < .001. (CREDIT: The Journal of Allergy and Clinical Immunology)
The findings of the study have significant implications for public health, as commercial dishwashers are widely used in various settings. The toxic effect of one ingredient in commercial rinse agents on the gastrointestinal tract could trigger the onset of many chronic diseases. It is, therefore, crucial to inform the public about this risk and take immediate action to prevent the negative health effects of these substances.
Ismail Ogulur, Yagiz Pat, Tamer Aydin, Duygu Yazici, Beate Rückert, Yaqi Penq, Juno Kim, Urszula Radzikowska, Patrick Westermann, Milena Sokolowska, Raja Dhir, Mubeccel Akdis, Kari Nadeau, Cezmi A. Akdis. Gut epithelial barrier damage caused by dishwasher detergents and rinse aids. The Journal of Allergy and Clinical Immunology.
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Note: Materials provided above by University of Zurich. Content may be edited for style and length.
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