Laser Technician (International Board of Electrologist Certification) IBEC Board Exam

What percentage of alcohol is typically used as a disinfectant?

1. 50%

2. 70%

3. 90%

4. 30%

The correct answer is: 70%

The use of 70% alcohol as a disinfectant is widely recommended because it effectively penetrates microbial cells, disrupting their ability to function and multiplying. This concentration demonstrates a balance that allows for optimal disinfection; it is low enough to ensure that the alcohol penetrates the cell wall of bacteria and viruses without causing immediate coagulation or denaturation of proteins, which can occur at higher concentrations. At percentages above 70%, such as 90%, the alcohol can evaporate too quickly to effectively kill pathogens because it does not remain in contact with the surfaces long enough. Lower concentrations, like 50% or 30%, may not provide the same efficacy in disrupting the cell membranes of microorganisms. Therefore, 70% alcohol is considered the standard concentration for disinfection in both clinical and non-clinical settings.