Scientific Proof

“Salmonella bacteria were isolated from the biofilm in the toilet bowl below the waterline for up to 50 (days) after seeding.”

“Four out of six households tested, Salmonella bacteria persisted in the biofilm material found under the recess of the toilet bowl rim which was difficult to remove with household toilet cleaners.”

“In addition, as common intestinal pathogens, norovirus and rotavirus can spread easily through the fecal–oral route because their main symptoms are acute diarrhea and vomiting"

"Numerous past studies have demonstrated that human coronaviruses (which are considered a major global public health threat), such as the severe acute respiratory syndrome-related coronavirus (SARS-CoV) and the Middle East respiratory syndrome-related coronavirus (MERS-CoV), are characterized by fecal–oral transmission.6,7 "

"Faced with these alarming results, we advocate several safe procedures to adopt when using a toilet:

Put the Lid Down Before Flushing

Clean the toilet seat before using it, since floating virus particles could have settled on its surface.

Wash hands carefully after flushing, since virus particles may be present on the flush button and door handle.”

“Nevertheless, many faecal–oral pathogens such as norovirus, rotavirus, Campylobacter and E. coli 0157 have infective doses as low as 10–100 micro‐organisms (Dupont et al. 1972; LeBaron et al. 1990; Tauxe 1992; Caul 1994; Griffin et al. 1994; McDonnell et al. 1995) and we speculate that surface‐to‐hand‐to‐mouth transfer could occur with the levels of contamination that we found on the surfaces surrounding the toilet.”

“ The risk of environmental contamination occurring in the bathroom is likely to be greatest during acute diarrhoeal illness when billions of micro‐organisms are being flushed down the toilet. During such episodes faecal material is likely to contaminate not only the bowl water but also the porcelain surfaces within the toilet bowl. Flushing produces aerosols from the force of the water running down the surfaces of the bowl and from the turbulence caused by mixing with water contained in the bowl.”

 “Many individuals may be unaware of the risk of air‐borne dissemination of microbes when flushing the toilet and the consequent surface contamination that may spread infection within the household, via direct surface‐to‐hand‐to mouth contact. Some enteric viruses could persist in the air after toilet flushing and infection may be acquired after inhalation and swallowing.”/p>

“Although a single flush reduced the level of micro‐organisms in the toilet bowl water when contaminated at concentrations reflecting pathogen shedding, large numbers of micro‐organisms persisted on the toilet bowl surface and in the bowl water which were disseminated into the air by further flushes.”

“Viruses are a significant cause of gastroenteritis worldwide and virtually all children aged 3–5 years acquire a rotavirus infection. Individuals with acute diarrhoea may shed >1010 infectious rotavirus particles per ml of faeces (Hart and Cunliffe 1999) and toilet flushing could spread aerosols containing the virus onto surfaces in the bathroom.”

“We also found that the recess under the rim of the toilet was heavily colonized with the test organisms.The recess under the rim of the toilet bowl has previously been found to be an area where Salmonella persisted in domestic homes where a family member had recently suffered an attack of salmonellosis with acute diarrhoea (Barker and Bloomfield 2000).”

“Multiple trips to the toilet during diarrhoea are likely to result in large numbers of pathogens persisting in the toilet, both on the porcelain surfaces and in the bowl water. Our studies have shown that such contamination is likely to result in continuing air‐borne spread on subsequent flushes. It would not be unreasonable to suggest that the persistence of enteric viruses within the air could be a potential infection risk via inhalation and swallowing. Air‐borne contamination could help to explain the high level of secondary spread of norovirus, within closed communities.”

“In our opinion the health risk of using the toilet is likely to arise during acute episodes of gastroenteritis with the shedding of large numbers of pathogens. In this investigation, we were able to show when simulating loose stool that material deposited both on the sidewalls and in the bowl water were involved in the dissemination of micro‐organisms into the air and onto surrounding surfaces. Epidemiological studies from recurrent outbreaks of norovirus infection in successive cohorts of guests in hotels and on cruise ships (Ho et al. 1989; Gellert et al. 1994; Cheesbrough et al. 2000), suggests spread from infected persons after vomiting by settling of aerosol particles onto surfaces which are then touched by hands. In addition, these studies suggested that splashing or aerosol generation during toilet flushing may spread virus particles onto contact surfaces such as the toilet seat or flush handle. Combined with our experimental data we believe that the potential spread of enteric disease by contact with surfaces in bathrooms harboring pathogens cannot be ignored and must be regarded as a serious infection risk”.

“ Another important viral pathogen is the SARS coronavirus (SARS CoV), which is known to be shed in both feces58, 59, 60 and vomit.60 A number of studies (discussed below) have suggested that it can be spread by the airborne route,61, 62, 63, 64 and, although not presently a common disease, it has demonstrated its potential for explosive spread and high mortality… Epidemiologic, experimental, and modeling studies of SARS are among the most compelling indicators of the potential for toilet plume to cause airborne disease transmission.”

“Disinfection is particularly important because many studies have shown that microbial surface contamination (including C difficile, vancomycin-resistant Enterococcus, and methicillin-resistant Staphylococcus aureus [MRSA]) may persist even after cleaning.”

“It may be concluded from the above that flush toilets produce substantial quantities of toilet plume aerosol capable of entraining microorganisms at least as large as bacteria, that sufficiently small microbe-laden droplets will evaporate to form droplet nuclei bioaerosols small enough to be inhaled deep into the lung, and that these bioaerosols may remain viable in the air for extended periods and travel with air currents. Production of these bioaerosols during multiple flushes after contamination suggests a long-term potential for a contaminated toilet to be an infectious bioaerosol generator.”

“A number of studies have demonstrated the contamination of toilet seats and lids, the surrounding floors, and the nearby surfaces by toilet flush aerosols.3, 6, 9, 10, 12, 13, 16 Because both the vomit and feces of infected persons may contain extremely high pathogen concentrations, eg, 105 to 109 Shigella,17 104 to 108 Salmonella,17 and 108 to 109 norovirus18 per gram of stool and at least 106 norovirus per milliliter of vomit,19 some fraction of the aerosol droplets produced during toilet flushing may be expected to contain microbes.20” C difficile was recovered from air sampled at heights up to 25 cm above the toilet seat and up to 90 minutes after flushing, at concentrations 12-fold greater with the lid up than with the lid down. They concluded that lidless conventional toilets increase the risk of C difficile environmental contamination and thus discouraged their use. In the United States, however, this would contradict current Uniform Plumbing Code specifications regarding toilet seat design and the installation of toilet seat lids on health care and other public facility “water closets”14 As well as similar requirements for gap-front seats without cover for water closets in the US Veterans Administration specifications often cited for health care facility design.”

“Studies of the 2009 H1N1 pandemic have conclusively shown airborne transmission via droplet nuclei, and the primary transmission mode is still considered to be by contact with large particle respiratory droplets or contaminated surfaces… that indicate a potential for airborne transmission via toilet plume… diagnosed during the 2009 pandemic H1N1 influenza outbreak. It has been measured in respirable-size aerosol in health care and other facilities,67, 68 has been detected in both stools and urine of H1N1 patients even in the absence of significant GI symptoms,69 and has shown a potential for extended virus shedding in stool.”

“A report on the 2003 SARS outbreak in Hong Kong's Amoy Gardens apartment complex concluded that exposure and disease propagation was likely due to virus-laden aerosols originating in the sanitary system.64 The system was contaminated with SARS CoV when the index patient, who was suffering from diarrhea, visited one of the apartments and used the toilet. Sewer drain bioaerosol was believed to be drawn through dry floor drain U-tube traps into the bathrooms of other apartments by bathroom exhaust fans, and some may have then been exhausted to the outside of the multistory building and carried upward to other apartments. Prevailing winds were thought to be responsible for carrying the infectious aerosol to nearby buildings where cases also occurred.63, 75 These studies suggest that SARS CoV droplet nuclei bioaerosols produced from contaminated sewage may have been highly infectious for significant periods and over long distances. Because the infectious waste, whether feces or vomit, is most concentrated in the toilet bowl and substantial quantities of aerosol are known to be produced during flushing, it might reasonably be expected that infectious SARS CoV droplet nuclei bioaerosol would also be produced during toilet flushing.To date, however, this has not been either experimentally or epidemiologically demonstrated.”

“The most significant toilet plume airborne infection risks are likely to be due to viruses, and perhaps the most significant of these is norovirus. Norovirus accounts for 73% to 95% of nonbacterial gastroenteritis outbreaks and half of all gastroenteritis outbreaks, worldwide.53 It may also be transmitted in aerosol and has a low infectious dose.54 It is shed both before and after—sometimes long after—the symptomatic phase of infection, is resistant to inactivation, and can persist on environmental surfaces for extended periods.55, 56, 57 Diarrhea and vomiting are both common with norovirus AGE, so both the use of toilets by infected persons and the toilet disposal of feces or vomit by other persons could produce norovirus bioaerosols.”

“For this study, toilets were seeded with microbe-size microbial surrogates and with Pseudomonas fluorescens or Clostridium difficile bacteria and flushed up to 24 times. Contamination still was present 24 flushes post contamination… This study shows that toilet bowl water will remain contaminated many flushes initial contamination, posing a risk of recurring environmental contamination and associated infection incidence.”

“It has been observed that toilet bowl water will remain contaminated for at least several flushes after the initial contamination, and microbial contamination can persist for days or weeks. Barker and Bloomfield (2000) detected residual microorganisms in bowl water 12 days after seeding the toilet with Salmonella, and in biofilm below the bowl waterline for 50 days after the seeding, suggesting a possible role of biofilm as a long-term reservoir and source of pathogenic organisms in the bowl water. Contaminated toilets will produce microbe-carrying aerosols during each flush (Barker & Jones, 2005; Darlow & Bale, 1959; Gerba et al., 1975; Yahya et al., 1992), with associated environmental re-contamination”.

“The potential for airborne transmission of sewage-related infectious disease was experimentally demonstrated over 100 years ago by Horrocks (1907), who found that sewage flowing smoothly in pipes as well as bursting bubbles in sewage would produce airborne microbes that could be transported substantial distances in the sewer system air while remaining viable”.

“Our results and those of previous investigators present a consistent body of data that demonstrates the potential for generation of infectious droplet nuclei bioaerosols when a contaminated toilet is flushed. Pathogens including Shigella, E. coli, Clostridium difficile, SARS coronavirus, and norovirus (Thomson 1955; Caul 1994; Atmar et al. 2008) can be present in vomit or stools of infected persons and can survive on surfaces for weeks or even months.”

“Both the vomit and feces of some infected persons may contain extremely high pathogen loads—concentrations of 105–109 Shigella (Thompson 1955), 104–108 Salmonella (Thompson 1955), and 108–109 norovirus (Atmar et al. 2008) per gram of stool and at least 106 noroviruses per milliliter of vomit (Caul 1994) have been reported.”

“Experimental work has clearly shown that droplet nuclei toilet plume aerosols are capable of entraining microorganisms as large as bacteria (Barker and Jones 2005), can migrate well away from the toilet (Jessen 1955; Darlow and Bale 1959; Barker and Jones 2005), and can remain viable for extended periods while airborne (Jessen 1955; Gerba et al. 1975; Barker and Jones 2005).”

“In the United States, 1.7 million immunocompromised patients contract a healthcare-associated infection, annually. These infections increase morbidity, mortality, and costs of care. A relatively unexplored route of transmission is the generation of bioaerosols during patient care.”

“Particle concentrations measured before and after the flush were found to be significantly different (0.3–10 μm). Bioaerosol concentrations when flushing fecal waste were found to be significantly greater than background concentrations (p-value = 0.005). However, the bioaerosol concentrations were not different across time (p-value = 0.977) or distance (p-value = 0.911) from the toilet, suggesting that aerosols generated may remain for longer than 30 min post flush.”

“Surface contamination may also occur from bioaerosols generated from infected patients or contaminated equipment. Studies examining healthcare settings have measured bioaerosol concentrations and characterized their composition to understand the generation source of bioaerosols during patient care [15,16,17,18,19,20,21]. The bioaerosols measured were composed primarily of bacteria identified as normal flora or infectious organisms [15,16,17,18,19,20,21]. Some of the identified organisms cause gastrointestinal illness, raising the concern that toilets are aerosolizing fecal waste.”

“SARS-CoV-2 is a non-segmented positive-sense RNA virus causing the third betacoronavirus outbreak of this century, which appears to have a higher transmission rate but is less deadly than the previous two; SARS-CoV 2003 and Middle East Respiratory Syndrome (MERS) 2012.3, 4 Prior studies demonstrated that the genome sequence of SARS-CoV-2 is 79.5% identical to SARS-CoV, whereas it shares 96.2% of its identity to the Coronavirus RaTG13 found in bats.”

“While patients infected with SARS-CoV-2 typically present with fever and respiratory symptoms, a rapidly increasing number of studies report patients presenting with a variety of gastrointestinal symptoms such as diarrhoea, vomiting and abdominal pain.”

“This study aims to (1) critically assess the clinical relevance of testing stool samples and anal swabs and (2) provide a critical overview of the available literature regarding the faecal-oral transmission of SARS-CoV-2.”

“The majority of the included studies were performed in China (74 (77%)), other studies were conducted in Korea (6), Singapore (2), the United States of America (5), Italy (4), France (1), Germany (1), Thailand (1) and Austria (1). All included studies had a case report/case series design. In most study populations, the subpopulation on which stool and/or anal testing were conducted was considerably lower. In total, stool samples or anal swabs (from now on collectively named as GI specimens) from 2175 patients were tested for SARS-CoV-2 RNA. Four studies were included for qualitative analysis, but due to the lack of necessary (follow-up) information, these studies were excluded before final quantitative analysis. 17-20 Therefore, 2149 patients were included for final analysis.”

“Twelve studies discussed the association between positive GI specimens and GI symptoms.13, 14, 19, 38-46 In all studies, the majority of patients with GI symptoms tested positive in GI specimens, but the association was not statistically significant in most studies. In the study by Han et al, it was observed that patients with GI symptoms were significantly more likely to test positive for SARS-CoV-2 in a stool test (P = 0.033).44 Furthermore, Cheung et al found that the proportion of positive stool tests and the stool viral load was higher in patients with diarrhoea than without (P = 0.019 and 0.06 respectively).”

“Coronaviruses are a family of single-stranded enveloped RNA viruses that are divided into four major genera. The genome sequence of SARS-CoV-2 is 82% similar to severe acute respiratory syndrome coronavirus (SARS-CoV),1 and both belong to the β-genus of the coronavirus family.2 Human coronaviruses such as SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), are known to cause respiratory and enteric symptoms.”

“In the SARS outbreak of 2002–03, 16–73% of patients with SARS had diarrhoea during the course of the disease, usually within the first week of illness.3 SARS-CoV RNA was only detected in stools from the fifth day of illness onwards, and the proportion of stool specimens positive for viral RNA progressively increased and peaked at day 11 of the illness, with viral RNA still present in the faeces of a small proportion of patients even after 30 days of illness.4 The mechanism for gastrointestinal tract infection of SARS-CoV is proposed to be the angiotensin-converting enzyme 2 (ACE2) cell receptor”.

“The 107 surface samples comprised 37 from toilets, 34 from other surfaces in isolation rooms (ventilated at 30-60 L/s), and 36 from other surfaces outside isolation rooms in the hospital. Four of these samples were positive, namely two ward door-handles, one bathroom toilet-seat cover and one bathroom door-handle; and three were weakly positive, namely one bathroom toilet seat, one bathroom washbasin tap lever and one bathroom ceiling-exhaust louvre. One of the 46 air samples was weakly positive, and this was a corridor air sample. The two exhaled condensate samples and the two expired air samples were negative.”

“The number of aerosols released ranged from 105 to 107 per flush from the toilets or per minute from the lab-scale models, and the total volume of aerosols generated by these systems was ∼10–9 to 10–7 mL per flush or per minute in all cases.”

"Particle concentrations measured before and after the flush were found to be significantly different."

"Toilet flushing aerosolizes fecal waste from the movement of toilet water (i.e., bubbling, swirling, splashing) during a flushing event [25]. Hutchinson (1956) isolated bacterial species found in fecal matter from toilets and bathroom surfaces. To determine how those surfaces are contaminated, several studies have aerosolized bacteria seeded in toilets".

"Particle and bioaerosol concentrations were measured in hospital bathrooms across three sampling conditions; no waste no flush, no waste with flush, and fecal waste with flush. Particle and bioaerosol concentrations were measured with a particle counter bioaerosol sampler both before after a toilet flushing event at distances of 0.15, 0.5, and 1 m from the toilet for 5, 10, 15 min".

"The particles aerosolized include microorganisms remaining from previous use or from fecal wastes. Differences in bioaerosol concentrations across conditions also suggest that toilet flushing is a source of bioaerosols that may result in transmission of pathogenic microorganisms."

"In situ testing of fecal suspensions of C. difficile detected the bug at heights of 25 cm above a toilet seat for as long 90 minutes after all the splashing and stirring of the environment that occurs when a toilet is flushed with its lid up (J Hosp Infect 2012;80[1]:1–5)."

"So gown, glove, hover, close (if the toilet has a lid), flush and run, because it appears that lids-down toilet flushing policies… aren’t exactly high on the priority list of hospital infection- control measures."

"Both patients had been hospitalized in the same room (room 1) of the hematology unit, 5 months apart. Air filtration systems with HEPA filters were used to control the environment of the unit. Water from the sink in each room and from the shower, shared by all of the unit’s patients, was filtered through 0.1-µm pore filters. Both patients were provided only bottled water and did not take showers during their hospital stay. In addition, there was no cooling tower within the hospital."

"It has been estimated that cross-infection contributes to 40% of cases of healthcare-associated infections and hand hygiene compliance represents an essential step in minimizing such infections."

"Viral pathogens such as Norovirus are thought to have a low infectious dose and can be shed in large numbers in faeces (Gerhardts et al. 2012). In a review, Kampf and Kramer (2004) cited studies that show that viruses can survive on the hands for varying times; Influenza and CMV (10–15 min), HSV (up to 2 h), Adenovirus (for many hours), Rhinovirus (7 days) and Rotavirus and HAV (up to 60 days).”

"It has been estimated that cross-infection contributes to 40% of cases of healthcare-associated infections and hand hygiene compliance represents an essential step in minimizing such infections."

"Viral pathogens such as Norovirus are thought to have a low infectious dose and can be shed in large numbers in faeces (Gerhardts et al. 2012). In a review, Kampf and Kramer (2004) cited studies that show that viruses can survive on the hands for varying times; Influenza and CMV (10–15 min), HSV (up to 2 h), Adenovirus (for many hours), Rhinovirus (7 days) and Rotavirus and HAV (up to 60 days).”

“Salmonella bacteria were isolated from the biofilm in the toilet bowl below the waterline for up to 50 (days) after seeding.”

“Salmonella enteritidis persisted in one toilet for 4 weeks after diarrhea had stopped, despite the use of cleaning fluids.”

“Four out of six households tested, Salmonella bacteria persisted in the biofilm material found under the recess of the toilet bowl rim which was difficult to remove with household toilet cleaners.”

“Salmonellas were NOT ISOLATED from normally dry areas such as the toilet seat, the flush handle and door handle.”

“Although a single flush reduced the level of micro‐organisms in the toilet bowl water when contaminated at concentrations reflecting pathogen shedding, large numbers of micro‐organisms persisted on the toilet bowl surface and in the bowl water which were disseminated into the air by further flushes”.

“Viruses are a significant cause of gastroenteritis worldwide and virtually all children aged 3–5 years acquire a rotavirus infection. Individuals with acute diarrhoea may shed >1010 infectious rotavirus particles per ml of faeces (Hart and Cunliffe 1999) and toilet flushing could spread aerosols containing the virus onto surfaces in the bathroom.” 

“Nevertheless, many faecal–oral pathogens such as norovirus, rotavirus, Campylobacter and E. coli 0157 have infective doses as low as 10–100 micro‐organisms (Dupont et al. 1972; LeBaron et al. 1990; Tauxe 1992; Caul 1994; Griffin et al. 1994; McDonnell et al. 1995) and we speculate that surface‐to‐hand‐to‐mouth transfer could occur with the levels of contamination that we found on the surfaces surrounding the toilet”.

“ The risk of environmental contamination occurring in the bathroom is likely to be greatest during acute diarrhoeal illness when billions of micro‐organisms are being flushed down the toilet. During such episodes faecal material is likely to contaminate not only the bowl water but also the porcelain surfaces within the toilet bowl. Flushing produces aerosols from the force of the water running down the surfaces of the bowl and from the turbulence caused by mixing with water contained in the bowl.”

“We also found that the recess under the rim of the toilet was heavily colonized with the test organisms. The recess under the rim of the toilet bowl has previously been found to be an area where Salmonella persisted in domestic homes where a family member had recently suffered an attack of salmonellosis with acute diarrhoea (Barker and Bloomfield 2000)”. 

“Multiple trips to the toilet during diarrhoea are likely to result in large numbers of pathogens persisting in the toilet, both on the porcelain surfaces and in the bowl water. Our studies have shown that such contamination is likely to result in continuing air‐borne spread on subsequent flushes. It would not be unreasonable to suggest that the persistence of enteric viruses within the air could be a potential infection risk via inhalation and swallowing. Air‐borne contamination could help to explain the high level of secondary spread of norovirus, within closed communities”. 

“In our opinion the health risk of using the toilet is likely to arise during acute episodes of gastroenteritis with the shedding of large numbers of pathogens. In this investigation, we were able to show when simulating loose stool that material deposited both on the sidewalls and in the bowl water were involved in the dissemination of micro‐organisms into the air and onto surrounding surfaces. Epidemiological studies from recurrent outbreaks of norovirus infection in successive cohorts of guests in hotels and on cruise ships (Ho et al. 1989; Gellert et al. 1994; Cheesbrough et al. 2000), suggests spread from infected persons after vomiting by settling of aerosol particles onto surfaces which are then touched by hands. In addition, these studies suggested that splashing or aerosol generation during toilet flushing may spread virus particles onto contact surfaces such as the toilet seat or flush handle. Combined with our experimental data we believe that the potential spread of enteric disease by contact with surfaces in bathrooms harbouring pathogens cannot be ignored and must be regarded as a serious infection risk”.

Please keep in mind these findings are from 2012….

“Studies of the 2009 H1N1 pandemic have conclusively shown airborne transmission via droplet nuclei, and the primary transmission mode is still considered to be by contact with large particle respiratory droplets or contaminated surfaces… that indicate a potential for airborne transmission via toilet plume… diagnosed during the 2009 pandemic H1N1 influenza outbreak. It has been measured in respirable-size aerosol in health care and other facilities,67, 68 has been detected in both stools and urine of H1N1 patients even in the absence of significant GI symptoms,69 and has shown a potential for extended virus shedding in stool”.

“Another important viral pathogen is the SARS coronavirus (SARS CoV), which is known to be shed in both feces58, 59, 60 and vomit.60 A number of studies (discussed below) have suggested that it can be spread by the airborne route,61, 62, 63, 64 and, although not presently a common disease, it has demonstrated its potential for explosive spread and high mortality”. Epidemiologic, experimental, and modeling studies of SARS are among the most compelling indicators of the potential for toilet plume to cause airborne disease transmission. A report on the 2003 SARS outbreak in Hong Kong’s Amoy Gardens apartment complex concluded that exposure and disease propagation was likely due to virus-laden aerosols originating in the sanitary system.64 The system was contaminated with SARS CoV when the index patient, who was suffering from diarrhea, visited one of the apartments and used the toilet. Sewer drain bioaerosol was believed to be drawn through dry floor drain U-tube traps into the bathrooms of other apartments by bathroom exhaust fans, and some may have then been exhausted to the outside of the multistory building and carried upward to other apartments. Prevailing winds were thought to be responsible for carrying the infectious aerosol to nearby buildings where cases also occurred.63, 75 These studies suggest that SARS CoV droplet nuclei bioaerosols produced from contaminated sewage may have been highly infectious for significant periods and over long distances. Because the infectious waste, whether feces or vomit, is most concentrated in the toilet bowl and substantial quantities of aerosol are known to be produced during flushing, it might reasonably be expected that infectious SARS CoV droplet nuclei bioaerosol would also be produced during toilet flushing. To date, however, this has not been either experimentally or epidemiologically demonstrated.”

“A number of studies have demonstrated the contamination of toilet seats and lids, the surrounding floors, and the nearby surfaces by toilet flush aerosols.3, 6, 9, 10, 12, 13, 16 Because both the vomit and feces of infected persons may contain extremely high pathogen concentrations, eg, 105 to 109 Shigella,17 104 to 108 Salmonella,17 and 108 to 109 norovirus18 per gram of stool and at least 106 norovirus per milliliter of vomit,19 some fraction of the aerosol droplets produced during toilet flushing may be expected to contain microbes.20” C difficile was recovered from air sampled at heights up to 25 cm above the toilet seat and up to 90 minutes after flushing, at concentrations 12-fold greater with the lid up than with the lid down. They concluded that lidless conventional toilets increase the risk of C difficile environmental contamination and thus discouraged their use. In the United States, however, this would contradict current Uniform Plumbing Code specifications regarding toilet seat design and the installation of toilet seat lids on health care and other public facility “water closets”14 As well as similar requirements for gap-front seats without cover for water closets in the US Veterans Administration specifications often cited for health care facility design.15”

“A critical determinant of the infection risk posed by a deposited pathogen will be the organism’s ability to survive on a surface.21 Many pathogens, including Shigella, E coli, C difficile, severe acute respiratory syndrome (SARS) coronavirus, and norovirus can survive on surfaces” 

“disinfection is particularly important because many studies have shown that microbial surface contamination (including C difficile, vancomycin-resistant Enterococcus, and methicillin-resistant Staphylococcus aureus [MRSA]) may persist even after cleaning.”

“The most significant toilet plume airborne infection risks are likely to be due to viruses, and perhaps the most significant of these is norovirus. Norovirus accounts for 73% to 95% of nonbacterial gastroenteritis outbreaks and half of all gastroenteritis outbreaks, worldwide.53 It may also be transmitted in aerosol and has a low infectious dose.54 It is shed both before and after—sometimes long after—the symptomatic phase of infection, is resistant to inactivation, and can persist on environmental surfaces for extended periods.55, 56, 57 Diarrhea and vomiting are both common with norovirus AGE, so both the use of toilets by infected persons and the toilet disposal of feces or vomit by other persons could produce norovirus bioaerosols”.

“Seeded a gravity-flow toilet with Salmonella enteritidis PT4 and collected surface wipe and air samples after flushing. They observed contamination of the toilet seat and the underside of the lid and also cultured Salmonella from the air sample. They detected Salmonella in the bowl water after 12 days and in bioofilm below the bowl waterline for 50 days after seeding”

“More recently, airborne transport of the SARS coronavirus by such sewage-related bioaerosols was proposed as the likely disease transmission mode in the 2003 SARS outbreak at the Amoy Gardens apartment complex in Hong Kong (Yu et al. 2004; Hong Kong Special Administrative Unit Department of Health 2011). Production of both large droplet and droplet nuclei bioaerosols during toilet flushing has been shown for a variety of toilet types and microorganisms”

“All three modern toilets produced hundreds to thousands of droplet nuclei “bioaerosol” particles with each flush, though there were differences across toilets in droplet nuclei aerosol production as measured by mean airborne concentration produced.. but it is difficult to imagine that such transmission is not occurring. Separating the incidence of disease transmission by contact and droplet routes from that by the airborne route is a challenge that remains to be met”.

“Our results and those of previous investigators present a consistent body of data that demonstrates the potential for generation of infectious droplet nuclei bioaerosols when a contaminated toilet is flushed. Pathogens including Shigella, E. coli, Clostridium difficile, SARS coronavirus, and norovirus (Thomson 1955; Caul 1994; Atmar et al. 2008) can be present in vomit or stools of infected persons and can survive on surfaces for weeks or even months (Kramer et al. 2006). As has been shown, hundreds to thousands of potentially infectious bioaerosol particles, capable of remaining airborne for extended periods and migrating with air currents, may be generated in a single flush of a toilet contaminated with these organisms. Whether a subsequent bioaerosol exposure results in disease would of course depend on the organism’s viability under existing environmental conditions, the number of organisms inhaled and their virulence, and the exposed person’s immune status among other factors (Cox 1987), but it is difficult to imagine that such transmission is not occurring”.

“It has been observed that toilet bowl water will remain contaminated for at least several flushes after the initial contamination, and microbial contamination can persist for days or weeks. Barker and Bloomfield (2000) detected residual microorganisms in bowl water 12 days after seeding the toilet with Salmonella, and in biofilm below the bowl waterline for 50 days after the seeding, suggesting a possible role of biofilm as a long-term reservoir and source of pathogenic organisms in the bowl water. Contaminated toilets will produce microbe-carrying aerosols during each flush (Barker & Jones, 2005; Darlow & Bale, 1959; Gerba et al., 1975; Yahya et al., 1992), with associated environmental re-contamination”.

“Surface contamination may also occur from bioaerosols generated from infected patients or contaminated equipment. Studies examining healthcare settings have measured bioaerosol concentrations and characterized their composition to understand the generation source of bioaerosols during patient care [15,16,17,18,19,20,21]. The bioaerosols measured were composed primarily of bacteria identified as normal flora or infectious organisms [15,16,17,18,19,20,21]. Some of the identified organisms cause gastrointestinal illness, raising the concern that toilets are aerosolizing fecal waste”.

“Toilet flushing aerosolizes fecal waste from the movement of toilet water (i.e., bubbling, swirling, splashing) during a flushing event [25]. Hutchinson (1956) isolated bacterial species found in fecal matter from toilets and bathroom surfaces. To determine how those surfaces are contaminated, several studies have aerosolized bacteria seeded in toilets. The target bacteria were detected in the air suggesting toilets are generators of bioaerosols”.

“In addition, as common intestinal pathogens, norovirus and rotavirus can spread easily through the fecal–oral route because their main symptoms are acute diarrhea and vomiting”

“Numerous past studies have demonstrated that human coronaviruses (which are considered a major global public health threat), such as the severe acute respiratory syndrome-related coronavirus (SARS-CoV) and the Middle East respiratory syndrome-related coronavirus (MERS-CoV), are characterized by fecal–oral transmission.6,7 “

“Faced with these alarming results, we advocate several safe procedures to adopt when using a toilet

1. Put the toilet lid down before flushing, which can basically prevent virus transmission.

2. Clean the toilet seat before using it, since floating virus particles could have settled on its surface.

3. Wash hands carefully after flushing, since virus particles may be present on the flush button and door handle.”

“Crystal Violet dye was added to both the bowl and tank water, and after covering the bowl with a sheet of white absorbent paper the toilet was flushed”.

“The number of bacteria and phage ejected from a toilet during a flush was found to be directionally proportional to the amount present at the time of a flush”