Organic acids, such as citric acids from lemons, generally lack good cleaning capability and fail to dissolve greasy substance. Further, they do not exhibit detergent like properties because they do not contain polar and non-polar portions within their chain. It is possible to increase the acid concentration to improve cleaning capabilities, however it would sacrifice other key characteristics desired of modern disinfectant products. Overall, in their typical disinfection concentration, organic acids do not exhibit strong cleaning behavior.
The germicidal efficacy of the various organic acid disinfectants is aslo a detrimental feature. They typically lack a broad spectrum of kill compared to higher level disinfectants such as bleach and hydrogen peroxide. Their mode of disinfection depends on the interaction of dissociated protons with microbial surfaces. Microbial membranes lose integrity in the reaction with free protons in solution. You may be thinking “Hey, wait! Vinegar and acetic acid have been used for hundreds of years as methods of disinfection and sanitization.” However, it is important to note that these only show strength against relatively easy to kill organisms such as pseudomonas. There is no current data that concludes that organic acids bolster a broad spectrum of kill.
From a safety perspective, the higher the concentration of the acid, the more dangerous it is. For instance, concentrate forms of acetic acid, citric acid and lactic acid are all extremely hazardous and can cause serious health problems to many parts of the body. However, they are safe to consume in the concentrations encountered in some of the foods we enjoy. The concentration of acetic acid in vinegar or citric acid in lemons is typically 4% to 8%. That being said, the safety is mainly dependent on the concentration and the type of organic acid.
Organic acids cause minimal toxicity in the environment at the concentrations they are used as disinfectants. This is because of their high solubility in water. When introduced into aquatic environments, the acids become diluted and thus less toxic. Furthermore, they cannot bio-accumulate within organisms or the environment because of this high water solubility. Finally, the degradation products of organic acids do not pose any threat to the environment, and are deemed “readily biodegradable” by the EPA.
This is how we would rate organic acid disinfectants based on the key decision making criteria:
• Speed of Disinfection – C to D
o Contact times range based on concentration and type of organic acid. They range from 10 minutes to hours for contact time.
• Spectrum of Kill – D
o This is the most daunting feature of organic acids because there is not enough data to show efficaciousness against a wide variety of both easy and difficult to kill organisms.
• Cleaning Effectiveness – C to D
o Organic acids do not exhibit high detergency properties, however it is closely tied to the concentration of the product.
• Safety Profile – B to C
o Organic acids are generally safe compounds as encountered, however they can become hazardous at high concentrations.
• Environmental Profile – A to B
o These disinfectants are readily biodegradable and easily dissolved in water, making them preferable to the environment.
• Cost Effectiveness – A to B
o Due to their availability, organic acids are usually cost effective methods; however price increases as concentration rises.
**For more in-depth scientific information about Organic acids and other disinfectant chemistries, stay tuned to www.infectionpreventionresource.com.