Commercial dishwashers come with a risk: potentially toxic substances from rinse aids can remain on the dishes, according to a new study published in The Journal of Allergy and Clinical Immunology.


Commercial dishwashers are those meant to wash, clean and dry plates, glasses and cutlery on a large scale, for use in restaurants, schools or barracks etc. These are different from consumer dishwashers, used in many homes for cleaning such objects.


The study was conducted by researchers at the Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich (UZH).


How does a commercial dishwasher work?


They noted that a typical commercial dishwasher works by circulating hot water and detergent for around 60 seconds at high pressure, after which there is another 60-second cycle for washing and drying, during which water and a rinse agent are applied. In many appliances, there is no additional wash cycle to remove the remaining rinse aids. With this in mind, the scientists examined the health effects of the components of commercial detergents and rinse agents.


The researchers worked with a newly developed technology, which uses human intestinal organoids and intestinal cells on microchips. Using various biomolecular methods, the team analysed the effect that commercial detergents and rinse aids have on these cells.


They looked specifically at the epithelial barrier in the gut, a layer of cells that lines the intestinal tract. Defects in this epithelial barrier are associated with food allergies, gastritis, diabetes, liver cirrhosis and various other conditions.


How do dishwashers pose health risks?


The scientists diluted the chemicals from detergents and rinse agents, so that these would reflect the amounts that would be present on dry dishes. They found that high doses of rinse agents killed the intestinal epithelial cells, while lower doses made it more permeable.


Also, one component of the rinse agent – alcohol ethoxylates – was found to activate several genes and proteins, which could trigger inflammatory responses.


“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. It is important to inform the public about this risk, since alcohol ethoxylates seem to be commonly used in commercial dishwashers,” a press release from UZH quoted Professor Cezmi Akdis, who led the study, as saying.