Bleach is an effective agent against E. coli, a bacterium commonly found in various environments that can pose health risks. Understanding how bleach works and how to use it properly is important for effective disinfection.
How Bleach Eliminates E. coli
Bleach, specifically its active ingredient sodium hypochlorite, functions as a powerful disinfectant by initiating a chemical process known as oxidation. When sodium hypochlorite comes into contact with bacterial cells like E. coli, it releases hypochlorous acid (HOCl) and hypochlorite ions (OCl-). These compounds are highly reactive and readily penetrate the cell walls of the bacteria.
Once inside the bacterial cell, these oxidizing agents disrupt the cell’s integrity by denaturing proteins and enzymes that are necessary for the bacterium’s survival and replication. This denaturation involves altering the three-dimensional structure of these biological molecules, rendering them inactive. The disruption extends to the cell membrane, making it permeable and leading to leakage of cellular contents. This widespread damage to the cellular machinery and structure ultimately results in the death of the E. coli bacteria.
Using Bleach Effectively Against E. coli
Achieving effective disinfection with bleach requires proper preparation and application. Before applying any bleach solution, it is important to clean surfaces of visible organic matter, such as food particles or dirt, using soap and water. Organic material can inactivate bleach, reducing its disinfecting power.
For general disinfection of non-porous surfaces like countertops and cutting boards, mix 5 tablespoons (1/3 cup) of household bleach per gallon of room temperature water, or 4 teaspoons of bleach per quart of room temperature water. Use cold water for dilution, as hot water can cause the sodium hypochlorite to decompose more rapidly, reducing its effectiveness.
After cleaning, apply the diluted bleach solution to the surface, ensuring it remains visibly wet for the necessary contact time. For most disinfection purposes, a contact time of at least 1 minute is recommended. Some sources suggest a longer contact time of 6 minutes for general disinfection against organisms like E. coli. After the contact time has elapsed, surfaces should be rinsed with clean water and allowed to air dry to remove any bleach residue.
Safety Considerations When Disinfecting
When handling and using bleach, ensuring adequate ventilation is important to prevent the inhalation of fumes. Opening windows and doors allows fresh air to circulate, diluting any airborne chemicals. Wearing protective gear, such as nitrile rubber gloves and eye protection, is also recommended to prevent skin and eye irritation from direct contact with the solution.
Never mix bleach with other cleaning products, especially those containing ammonia or acids. Combining bleach with ammonia can produce dangerous chloramine gases, while mixing it with acids can release toxic chlorine gas. These gases can cause severe respiratory issues or even be fatal. If a surface requires cleaning with another product, it should be thoroughly rinsed with water before applying bleach.
Undiluted household bleach has a shelf life of about six months to one year when stored properly. After this period, the sodium hypochlorite active ingredient begins to degrade, becoming less effective. Diluted bleach solutions should be prepared fresh daily, as their disinfecting properties diminish significantly after 24 hours. Bleach should be stored in a cool, shaded place, away from direct sunlight and out of reach of children, to maintain its efficacy and prevent accidental ingestion.