It comes from the love of nature and the nature of the work. Biologists have a heightened awareness of surface contamination and a preference for eco-friendly decontamination methods. It’s more important than ever to connect that awareness to effective lab practices.
There are good reasons to review disinfectant practices. Panic-driven, excessive use of disinfectants over the past couple of years will have long-term environmental outcomes. There have been upsetting immediate consequences of wildlife deaths from outdoor disinfectant use. Unfortunately, excessive outdoor spraying of disinfectants continues in some parts of the world. The U.S. EPA is in the midst of developing protocols to study the environmental risks of these pollutants.
At the same time, small studies in healthcare and clinical microbiology laboratory-based settings show that nearly half of cleaned and disinfected surface samples still carried microbes, viruses or associated nucleic acid contaminates. It’s concerning. Not only do we want to prevent infection, but the best laid experimental plans can be laid waste by contamination.
What’s going on here?
Effective use can prevent excessive use
Sustainability researchers are highlighting that while chemistry improves our lives poor health, scientific and ecological outcomes result from improper use. Let’s review best practices for the most common lab surface disinfectants; bleach and ethanol.
Alcohols disinfectants work by coagulating and denaturing proteins fast but it isn’t precisely instantaneous. The study Dong-Wook Kim et al Evaluation of Efficacy about Disinfectants in Biological Containment Facilities (2021) Jrnl. of Bacteriology and Virology demonstrated that how disinfectants are used matters in biological laboratories. Spraying 70% alcohol solutions alone was ineffective for bacteria and viruses. To be effective, a 70% to 95% diluted ethanol spray should be left for two minutes and then must be wiped away by a non-woven fabric. Whiles some reports claim sufficient mechanism with isopropanol solutions in less than sixty seconds, the two-minute soak method followed by fabric wipe is also the EPA COVID-19 guideline for ethanol disinfectants. I know I’ve been guilty of wiping down benchtops and cell culture hoods too quickly. How about you?
Sodium hypochlorite inhibits DNA synthesis and cellular activity by oxidation. Sodium hypochlorite is highly toxic, but it is also extremely reactive so does not bioaccumulate or persist in the environment with proper dilution with water. Increased concentrations of bleach can still be eco-toxic. Using bleach involves a lot of “nevers” and like ethanol - using the right concentration for the right amount of time. Regular surface disinfection time with a 0.1% bleach disinfectant solution is ten minutes. The CDC recommends making fresh 0.1% chlorine solution each day for disinfection.
Typically there are safety systems in place in labs that account for specialized bleach decontamination. Biology labs use 10% solutions of lab bleach, which actually works out to 1.25%, to decontaminate cultured cells and viruses for at least thirty minutes in vacuum flasks. Molecular biology labs also often decontaminate equipment with high concentration bleach solutions. Lab wastewater systems are engineered to neutralize bleach before it reaches municipal wastewater. Residuals are measurable at a lab facility’s wastewater outlet to meet water standards.
Scientists working in labs can take heart in that and focus on refreshing themselves on safety. There are important “nevers” associated with bleach. Never store bleach solutions in direct sunlight. Never autoclave bleach solutions. Never apply it to metal surfaces or your skin. Avoid aerosolization which can cause respiratory irritation. Never mix bleach with alcohols or acids which risks dangerous fumes and wastewater byproducts.
Protect yourself and the environment
Proper disinfection calls for goggles, gloves, and good ventilation. While ventilation is a key feature of labs, the current stumbling block can be the gloves. There is still a massive lab glove supply chain problem. According to a CNN investigation, Tens of Millions of Filthy, Used Medical Gloves Imported Into the US an ongoing scam sells gross used lab gloves in fake packaging with reputable brand names. Ug.
Whenever your work doesn’t necessitate lab gloves, hand washing with biodegradable soap is better for your skin and the environment than ethanol-based sanitizers. Synthetic soap is mainly petroleum-based and can impact aquatic organisms through wastewater. Alcohol-based hand sanitizers have also been linked with infectious disease outbreaks. On the other hand, pun intended, biosurfactants are safe and useful in both pharmaceutical and biomedical work. Just keep in mind that biodegradable soaps do not rinse away easily if you are washing room surfaces instead of your hands. A follow-up rinse is needed to prevent sticky areas that could accumulate food sources for bacteria or fungus.
Ecologically speaking moderation is key. Discharge of disinfectants and their mixing to form by-products in sewage and freshwater can impact aquatic life and foster long-term health problems in people. Increased disposal over time leads to natural selection for alcohol or bleach-resistant bacteria. Biodegradable soaps can be a great alternative to synthetic soaps in labs. Disinfectant application time, concentration, and wastewater setup feed into effective, eco-friendly usage. Environmental science findings on disinfectants should reinforce our commitment to their proper use.
Thank you for being labconscious!
