Virucidal Efficacy of Household Dishwashers

Not only since SARS-CoV-2, have transmission routes of viruses been of interest. Noroviruses e.g., can be transmitted via smear infection, are relatively stable in the environment and very resistant to chemical disinfection. Some studies determined the virucidal efficacy of laundering processes, but few studies focused on the virucidal efficacy of dishwashing processes. Here, especially consumer related conditions are of interest. Households for example are a hotspot of norovirus infection and thus a sufficient reduction of these and other viruses from dishes must be insured to avoid an infection via this route. The likelihood of such an event should not be underestimated, since it was shown that the washing machine can be a reservoir for the transmission of extended spectrum beta-lactamase producing bacteria in newborns. Although viruses do not replicate in these devices a transmission via contaminated cutlery e.g., cannot be excluded. Using a consumer related approach to determine the virucidal efficacy of dishwashers, we found a combination of a bleach containing dishwasher detergent, a cleaning temperature of 45 °C for 45 min and a rinsing temperature of 50 °C, to be sufficient to reduces viral titer of bovine corona virus, murine norovirus and modified vaccinia virus by 4.8, 4.2 and 3.8 logarithmic stages respectively.

Simple, Low-cost and Semi-permanent Film for Virus Inactivation Using Avian Coronavirus Model as Challenge

COVID-19 infection, caused by SARS-CoV-2, is inequitably distributed and more lethal among populations with lower socioeconomic status. Direct contact with contaminated surfaces has been one of the virus sources, as it remains infective up to days. Several disinfectants have been shown to inactivate SARS-CoV-2 but they rapidly evaporate, are flammable or toxic and may be scarce or inexistent for the vulnerable populations. Therefore, we are proposing a simple, easy to prepare, low-cost and efficient antiviral films, made with wide available dishwasher detergent, which can be spread in hands and inanimate surfaces and maintains virucidal activity for longer periods than the current sanitizers. Avian coronavirus (ACoV) was used as model of challenge to test the antivirus efficacy of proposed films. Polystyrene microplates were covered with a thin layer of detergent formula. After drying, the films were exposed to different virus doses for 10 minutes and virus infectivity were determined using embryonated chicken eggs and RNA virus quantification in allantoic fluids by RT-qPCR. The films showed to inactive the ACoV (ranging from 103.66 to 106.66 EID50), which is chemically and morphologically similar to SARSCoV-2 and may constitute an excellent alternative to minimize the spread of Covid-19.

Scalding Water Temperatures

Tap water scald burns are the most frequent cause of nonfatal burn injuries in United States children. Most of these burns occur in the home, and hot water heater thermostat settings below 60°C (140°F) significantly decrease the risk of such burns in young children. The American Academy of Pediatrics and other safety-promotion organizations recommend that thermostats be set at 49 to 53°C (120 to 130°F), and ordinances encouraging lower hot water temperatures exist in some localities. We advise our pediatric colleagues that consumer products manufacturers do not always follow these recommendations in their published guidelines for product use. Specifically, we have found that four of five major manufacturers of automatic dishwasher detergent recommend hot water thermostat settings of 60°C or higher. (See Table.)

In Reply: Scalding Water Temperatures

The observations by Lukefahr and Ezekiel regarding scald burns and the potentially harmful recommendations by some manufacturers of automatic dishwasher detergent brands are well taken. The American Academy of Pediatrics has supported changes in building codes to stipulate that water heaters be set at safe temperature levels (125 to 130°F) when installed and model state legislation was drafted requiring all water heaters leased or sold to be preset at 120°F. Manufacturers' acceptance and adherence is anticipated.