Detergent presence after washing dishes in a washing machine

Abstract Background Currently, about half of the European population has a dishwasher for domestic use and, following the trend of the last decade, this number is expected to increase in the coming years. Various types of detergents are available on the market for these machines, including some that incorporate chemical substances in the formula that can be harmful to humans. If machines are not able to efficiently remove detergent at the end of washing, chemicals can enter the human food chain and cause long-term damage. Methods This study aims to evaluate the effectiveness of dishwashers in removing the detergents used during the washing. The study was carried out in the village of Friúmes, in Penacova - Coimbra, in dwellings that had a dishwasher, ten machines were selected at random, located in different residences. The sample collected represents the execution of thirty analyzes in dishes and thirty in glass, with a phenolphthalein indicator. Results As a result of the study, and after finishing the washing cycle, the presence of detergent was detected in 4 dishes (13.3%) and in 10 glasses (33.3%), demonstrating flaws in the removal of the chemical during the washing period. It is verified that the number of chemicals increases at the end of washing, in the glasses compared to the dishes. Conclusions The design of the glass can have an influence on the results. However, further studies are needed as the bioaccumulation of these products can pose risks to people's health.