








key: cord-295034-em6z8mlu
authors: Daverey, Achlesh; Dutta, Kasturi
title: COVID-19: Eco-friendly hand hygiene for human and environmental safety
date: 2020-11-11
journal: J Environ Chem Eng
DOI: 10.1016/j.jece.2020.104754
sha: 
doc_id: 295034
cord_uid: em6z8mlu

The Coronavirus disease-2019 (COVID-19) outbreak is caused by a highly pathogenic novel coronavirus (SARS-CoV-2). To date, there is no prescribed medicine for COVID-19. Frequent handwashing with soap and the use of alcohol-based hand sanitizers is recommended by WHO for hand hygiene and to prevent the spread of COVID-19. However, there are safety concerns associated with the use of soaps and alcohol-based hand sanitizers. Therefore, the review aims to highlight the health and environmental concerns associated with the frequent use of soaps/detergents and alcohol-based hand sanitizers amid COVID-19. The potential of some of the natural detergents and sanitizing agents as eco-friendly alternatives to petrochemical-based soaps and alcohol-based hand rubs for hand hygiene are discussed. The market of soaps and hand sanitizers is expected to grow in the coming years and therefore, future research should be directed to develop eco-friendly soaps and hand sanitizers for human and environmental safety.

Coronavirus Diseases 2019 (COVID- 19) , which was first reported in Wuhan city (China) J o u r n a l P r e -p r o o f hydrogen peroxide (0.125% v/v as a preservative to inactivate bacterial spores) and glycerol (1.45% v/v as a humectantmoisturizing agent) diluted with sterilized distilled water or boiled water (WHO, 2010). In commercial products, propylene glycol is being used as a humectant. A viscosity enhancer such as alkyl acrylate cross-polymer, tetrahydroxypropyl-ethylenediamine, etc. is usually added in alcohol-based hand-rub gels. The cost of alcohol-based liquid and gel sanitizers is ranged around US$ 2.5-5.4 and US$ 8, respectively (WHO, 2010).

The mechanism of killing the microorganisms by soaps or detergents relies on the fact that they disrupt the lipophilic membrane of the cell wall of bacteria and other microorganisms including enveloped viruses (Ijaz et al., 2020) . Similarly, alcohol also dissolves the lipid membrane of microorganisms. Literature suggests that ethanol is highly effective (within 30 s) against almost all clinically relevant enveloped viruses including coronaviruses (SARS-CoV i.e. Severe Acute Respiratory Syndrome Coronavirus and MERS-CoV i.e. the Middle East Respiratory Syndrome Coronavirus, which belong to the same class of viruses as SARS-CoV-2), and influenza viruses (Kampf, 2018; Golin et al., 2020) . Therefore, alcohol-based hand sanitizers with alcohol content >60% v/v are popular and recommended by WHO and other national organizations such as CDC (Centers for Disease Control and Prevention), USA (CDC, 2020). The recent study by Kratzel et al. (2020) reports that SARS-CoV-2 was efficiently inactivated by ethanol and 2-propanol at a concentration of >30% v/v and by the two preparations recommended by WHO in 30 s. That's why frequent hand washing with soaps and hand hygiene with alcohol-based hand sanitizers has been recommended. The simplified mechanism of soaps/detergents and alcohol-based hand sanitizers are presented in Fig. 1 . pandemic is yet to be quantified.

The general safety issues associated with alcohol-based hand sanitizers are flammability of alcohol and toxicity due to the accidental ingestion of the sanitizer. In a recent review by Though the key components of hand sanitizers, alcohol and H 2 O 2 are in general not toxic externally, there is a concern of skin damage due to excessive use of hand sanitizers, which can lead to an inability of the skin to protect against other microorganisms or viruses (Mahmood et al., 2020). Younger kids (12-year-old children or younger) are at high risk due to accidental ingestion. In children, even a small dose of alcohol can cause alcohol poisoning. Therefore, the American Association of Poison Control Center (AAPCC) regarded hand sanitizers as emerging hazards. In the first six months (January to June 2020), 11,363 cases of exposure due to hand sanitizer have been reported according to AAPCC (https://aapcc.org/track/hand-sanitizer).

Methanol contamination has also been found in hand sanitizers probably due to the high demand for ethyl alcohol and isopropyl alcohol during this pandemic. FDA (U.S. Food & Drug Administration) found methanol contamination in several tested hand sanitizers (77 products as on July 23, 2020) and advises consumers not to use hand sanitizers from certain manufactures (FDA, 2020). Therefore, there is a dire need to replace alcohol-based hand sanitizers with nontoxic or low-toxic hand sanitizers for human and environmental safety.

Antimicrobial resistance due to the rampant use of antibiotics and other antimicrobial agents has become one of the major concerns worldwide. Apart from antimicrobials (antibiotics, antivirals, and antiparasitics), excessive use of surfactants, alcohol, and hydrogen peroxides are also known to cause resistance to microorganisms (Singer et 

Many microorganisms (bacteria, yeasts, and fungi) and plants produce surface-active agents called biosurfactants. Chemically they are amphiphilic compounds i.e. have both lipophilic and hydrophilic moieties in their structure. The biosurfactants possess similar properties as their chemical counterpart. For example, they efficiently reduce the surface and interfacial tensions between two phases, act as emulsifiers, and have foaming properties. Therefore, biosurfactants are potential agents to replace synthetic surfactants in soaps and detergents.

Based on their chemical structure microbial biosurfactants are classified as glycolipids, In the Kumaun region of Uttarakhand (India) 22 plant species have been used as traditional soaps and detergents. Different plant parts such as seeds, seed coats, barks, leaves, and young shoots, roots, ash have been used for washing and bathing purposes by the local people (Mehta and Bhatt, 2007) . Overall, all these properties of plant-derived natural soaps and detergents have the potential to replace the synthetic detergents and alcohol-based sanitizers. However, in-vitro J o u r n a l P r e -p r o o f activities of these natural biosurfactants against coronaviruses and SARS-CoV-2 has to be tested before using for hand hygiene.

Propylene glycol is the most commonly used humectant in hand sanitizers due to its low cost. A viscosity enhancer such as carbomer hydroxyethyl cellulose, sodium carboxymethyl cellulose, etc. is also added in the hand rubs. Aloe vera gel, a transparent mucilaginous jelly-like material (Lin et al., 2017) . Lemon balm oilan essential oil, which inhibits the enveloped herpes simplex virus and phenolic compounds from the Isatis indigotica, which inhibits coronavirus, could also inactivate SARS-CoV-2 (Jahan and Ahmet, 2020). However, the low-yield of essential oils and phenolic compounds could be a major factor for their commercial application in hand-sanitizers.

The main raw material used in soaps and hand sanitizers is petrochemicals based surfactant and 

Good hand hygiene prevents the spread of various diseases including COVID-19. Handwashing with soaps and the use of hand sanitizers to clean hands have increased immensely during the COVID-19 pandemic. The global market of detergents and hand sanitizers is expected to grow in the coming days. However, considering the harmful effects of chemical detergents and hand sanitizers, it is high time to replace them with eco-friendly natural agents. Several microbial J o u r n a l P r e -p r o o f biosurfactants and plant secondary metabolites possess detergent, antimicrobial and antiviral activities. Being non-toxic and biodegradable, these eco-friendly agents have tremendous potential to replace conventional soaps and hand sanitizers. Economical production of biosurfactants and extraction of bioactive antimicrobial agents from the plants will play a crucial role in their commercial application and sustainability as eco-friendly soaps and hand sanitizers and therefore further research is needed in this direction. 

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