New study finds that closing the toilet lid when flushing isn't all that effective for cutting down viral contamination

Sorry, folks, I've got some real shitty news for you. Turns out that closing your toilet lids when flushing isn't all that effective for cutting down viral contamination. At least, that's what a team of researchers reported in a recently published study in the American Journal of Infection Control, entitled, "Impacts of lid closure during toilet flushing and of toilet bowl cleaning on viral contamination of surfaces in United States restrooms." 

It's widely known that flushing the toilet sends plumes of aerosols into the air. And we also know that aerosol plumes can contain fecal matter, pathogenic material such as viruses, and more. Conventional wisdom has led us all to believe that closing the toilet lid during flushing is a good way to reduce the contamination created by flushing toilets. According to the authors of this new study, this assumption hasn't been demonstrated empirically. They set out, then:

. . . to determine if closing the toilet lid prior to flushing actually reduces the viral contamination of household restrooms, as has been suggested, and if cleaning of the toilet bowl has an impact. This information will inform the potential benefit of these risk mitigation strategies for use as environmental surface hygiene interventions during future viral outbreaks, including those associated with enteric viruses such as noroviruses.

The study found that there is no statistically significant difference between leaving the toilet lid up and closing the toilet lid before flushing, with regard to contaminating bathroom surfaces. The authors did find, though, that disinfecting the toilet bowl does reduce the risk of cross-contamination of bathroom surfaces. Researchers Madison Goforth, Stephanie Boone, Justin Clark, Priscilla Valenzuela, Julie McKinney, M. Khalid Ijaz, and Charles Gerba summarize their paper:

Viral aerosols from toilet flushing pose a possible route of pathogen transmission.

Toilet lid closure prior to flushing is believed to mitigate cross-contamination.

We show toilet lid closure prior to flushing does not mitigate cross-contamination.

Brushing toilet bowl without disinfectant results in contamination of surfaces.

The use of a disinfectant during bowl cleaning reduces cross-contamination of surfaces.

The study concludes:

Our study demonstrated that lid position (up or down) prior to flushing of household or public toilets of United States design seeded with MS2 bacteriophage had no significant effect on the MS2 cross contamination of household restroom surfaces. MS2 was recovered from all restroom surfaces tested, and lid closure had no impact on the results. The most effective strategies for reducing restroom cross-contamination associated with toilet flushing include the addition of a disinfectant to the toilet bowl before flushing and the use of disinfectant/detergent dispensers in the toilet tank. To reduce the risk associated with exposure to contaminated fomites in the restroom, regular disinfection of all restroom surfaces following toilet brushing, and/or use of a disinfectant that leaves residual microbicidal activity is suggested particularly when the household is occupied by an individual with an active infection with a virus, such as norovirus, causing acute gastroenteritis. Because many viral infections may be asymptomatic, this is even more important in health care facilities where immunocompromised individuals are often present.

I think I'll go get one of those toilet bowl disinfectants that sits in the tank and is activated with every flush. Seems like it can't hurt, and possibly might help! I'll also continue to mask in public restrooms, thank you very much.

Read the entire article here.