Abstract
With the deteriorating situation caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes novel coronavirus disease 2019 (COVID-19), it is not surprising that there has been a tremendous rise in the purchase and use of disinfectants. The virus spreads by human-to-human interactions and exposure to coughing, sneezing, respiratory droplets and aerosols from an infected person, in addition to, interactions with contaminated surfaces.1,2 On contaminated surfaces such as metal, glass, and plastic, human coronaviruses can survive from several hours up to 9 days, highlighting the need to disinfect surfaces effectively. 2 Hence, there is a wide range of marketed disinfectants such as household bleach, alcohol, and hand sanitizers that can be used to prevent and control the spread of the virus. Although disinfectants can be effective, if misused, they can also be hazardous to humans as well as to the environment. 3 The active biocidal ingredients of these products range from natural materials such as ethanol, L-lactic acid, citric acid, and hydrogen peroxide to synthetic substances such as sodium hypochlorite, hypochlorous acid, quaternary ammonium compounds, octanoic acid, peroxyacetic acid, and glycolic acid at different concentrations.3,4 Table 1 presents some of the most widely used natural and synthetic surface and hand disinfectants approved by the Environmental Protection Agency for the prevention of SARS-CoV-2. 4 Although all of these products should be used with the manufacturers' recommended precautions, the utmost care must be used with some due to their potentially high level of toxicity and risk to human health. 7
Commonly Marketed Disinfectants Against SARS-CoV-24- 6
The National Institute for Occupational Safety and Health recommended exposure limits for up to a 10-hour time weighted average.
American Conference of Governmental Hygienists.
Abbreviation: ppm, parts per million.
Risk of Disinfectant Use on Health
According to Chang et al, 7 the National Poison Data System reported a substantial increase in cases of disinfectant poisoning during the present COVID-19 outbreak. Notably, cases related to poisoning exposure showed that bleach products (62.1 %) accounted for the largest percentage of poisoning prior to and during COVID-19, followed by nonalcohol disinfectants (36.7%) and hand sanitizers (36.7%). The main route of exposure reported was by inhalation, which increased substantially by 35.3% during the first few months of the COVID-19 pandemic. 7
Commonly known bleach (chlorine) is a surface disinfectant made of sodium hypochlorite. It is recommended for use at a concentration of 0.1% or 1,000 parts per million (1 part of 5% strength household bleach to 49 parts of water). Alcohol at 70% to 90% strength can also be used for surface disinfection. 8 However, these are also known to cause irritation of the skin and eyes, irritation to the respiratory tract, and asthma in some individuals. 3 Moreover, the use of bleach results in the formation of toxic halogenated volatile organic compounds in the indoor air including carbon tetrachloride, chloroform, 1,1-dichloroethene and 1,1-dichloroethane, and chlorobenzene. 9 The concentrations of these chemicals detected in the air 30 minutes after application were higher than those detected before application, indicating that the use of bleach may be an important source of inhalation exposure for these compounds. 9
Hand disinfection (sanitizers) has been considered critically important, as SARS-CoV-2 can be transmitted by touch and last on hands from 10 min up to 2 hours. 10 The Centers for Disease Control and Prevention recommends that a minimum of 60% ethanol can maintain hand hygiene and effectively reduce the number of pathogens present in the hands. Alternatively, some hand sanitizers contain benzalkonium chloride (or quats), a quaternary ammonium compound that can irritate the skin and respiratory system and may induce asthma in some individuals.10,11 Unsurprisingly, hand sanitizer use has been at a peak during this pandemic. While people have been using hand sanitizers on a daily basis, often multiple times a day, it is important to investigate whether those chemicals are safe at that level of exposure, especially for pregnant women and children. What has also been evident is that consumers have been inadvertently exposed to hand sanitizers that can be highly detrimental to health. For example, the US Food and Drug Administration has recalled many sanitizers containing methanol, which can cause vomiting, headaches, blurred vision, permanent blindness, seizures, coma, permanent damage to the nervous system, or death. 12 In Canada, hand sanitizers have been recalled because they contain industrial-grade ethanol, which is not authorized for use on hands. 13 In the United Arab Emirates, hand sanitizers have been recalled due to low alcohol content (≤60% alcohol), which is considered ineffective for fighting viruses. 14
Additionally, there are concerns that using antibacterial hand sanitizers can contribute to antibiotic-resistant bacteria as well as the loss of a barrier to protect against the coronavirus. 15 It is, therefore, clear that there is a need to formulate safe and effective disinfectants and raise consumer awareness to potential health hazards. The ideal disinfectant should have a low toxicity profile with short- and long-term exposure. Since the majority of the disinfectants are able to kill or inactivate a wide range of microorganisms, it is crucial to understand the exposure time needed to target specific pathogens of interest with minimal risks.
Conclusions
In summary, disinfection is crucial in the prevention and spread of COVID-19; however, disinfection should be carried out with appropriate precautions to reduce exposure to harmful byproducts. A compound recently added to the Environmental Protection Agency's list 5 is thymol, a natural phenolic compound obtained from thyme oil. Such alternative measures can include the use of less toxic chemical disinfectants such as naturally occurring substances, which include thymol, ethanol, and hydrogen peroxide, to limit risks to humans and the environment. Since these substances are used in low concentrations or decompose rather rapidly, they leave no toxic residues. 16 Moreover, appropriate personal protective equipment should be worn to avoid inhalation, and careful consideration must be given to chemical use, concentrations, room ventilation, and application technique. 17 In the case of hand disinfection, nonirritating soaps and alcohol-based hand sanitizers should be used instead of detergents and hand sanitizers containing benzalkonium chloride, which can exacerbate skin damage and irritation. 10 Use of hand sanitizers, though, should be limited, as they can raise the risk of infection by disrupting the normal flora and irritating the skin, which normally acts as a barrier to harmful agents. Although no safe chemicals exist, there is a continued need to enhance consumer awareness and develop disinfectants that are less harmful to humans and the environment.