In addition to having general knowledge of potential microorganisms present in a water damage restoration project, restorers should have an understanding of the proper use of agents that can help control the growth of these microorganisms and reduce potential risks associated with some of their metabolic by-products (e.g., endotoxins, mycotoxins). The intent of this article is to provide a general overview of technology, regulatory considerations, product application, and safety and risk management.
Microbiological growth is inevitable when moisture, nutrients, and moderate-to-warm temperatures are present. It is important to recognize that not all water intrusions warrant the use of biocides. Thus, it is important for restorers to evaluate whether biocide application is likely be beneficial.
There are several steps in the restoration process that restorers can perform or facilitate, which might return the structure to a sanitary condition without using biocides. These steps can include: stopping the source of moisture intrusion, removing contaminated materials, thorough cleaning, and rapid, drying of affected materials, systems and contents to acceptable moisture content (MC). Note, however, that unless otherwise agreed to by materially interested parties, it is the responsibility of the property owner, not the restorer, to correct the source of the water intrusion, or to engage appropriate specialized experts to do so.
There are potential benefits to biocide use. In situations where drying a space is slow or difficult, a biocide might extend the time before microorganisms would ordinarily begin to grow. Further, controlling microbial growth prevents the amplification of bacteria, allergenic debris, irritants, and endotoxins, which can have human health implications. Biocides can also be part of a decontamination process when pathogenic organisms are present. Along with other cleaning products and processes, biocides can play an important role in limiting the spread of bio-contamination and disease. Because of the reasons discussed in this paragraph, biocides are at times used in a preventative or curative role.
There are also factors that might preclude the use of a biocide. Most biocides are deactivated by organic matter in water or on surfaces (e.g., chlorine-based formulations, alcohol, peroxide, quaternary ammonium compounds); therefore, pre-cleaning is usually an essential first step. In addition, most biocides require physical contact with affected surfaces for substantial periods of time (10-30 minutes) to be effective. Some biocides, which can be strong irritants or sensitizers, might not be appropriate for application in close proximity to building occupants who could be exposed and adversely affected. Finally, products with strong odors can be undesirable to some customers or occupants. In all cases, biocides should be applied following label instructions. In determining biocide use, restorers should weigh the benefits of using biocides against the risks associated with their use, and any client or customer concerns or preferences.
Definition and Regulation
Antimicrobials are substances used to destroy (biocides) or suppress growth (growth inhibitors/static agents) of microorganisms (i.e., bacteria, viruses, or fungi) on inanimate objects, surfaces, and materials. The United States Environmental Protection Agency (USEPA) Antimicrobials Division registers and regulates antimicrobial products (which the Agency refers to as pesticides) under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). Some jurisdictions require commercial applicators of antimicrobial products to be licensed, certified, or to be specially trained.
Classes of antimicrobial products include sanitizers, disinfectants, sterilizers (sporicides), and growth inhibitors:
Sanitizers: Products used to reduce, but not necessarily eliminate, microorganisms from the inanimate environment to levels considered safe as determined by public health codes or regulations.
Disinfectants: Products that kill or inactivate at least 99.9% of disease-producing (pathogenic) microorganisms on inanimate objects. Used to destroy or irreversibly inactivate infectious fungi and bacteria but not necessarily their spores.
Sterilizers (sporicides): Products used to destroy or eliminate all forms of microbial life including fungi, viruses, and all forms of bacteria and their spores.
Growth Inhibitors (bacteriostats, fungistats): Products used to treat surfaces or be incorporated into materials to suppress or retard future vegetative bacterial and fungal growth under moist conditions.
Other commonly used terms and their definitions include the following:
Antimicrobial: Substances that kill or control microorganisms (such as bacteria, fungi, viruses) or inhibit growth of microorganisms.
Bacteriostat: A compound that suppresses bacterial growth when used according to label directions. The suffix "-stat" means to inhibit growth without necessarily killing targeted organisms.
Biocide: Any substance that kills living organisms. The term is used commonly within the water damage restoration industry to describe an agent that kills microorganisms or controls amplification. Descriptions of products specific to a target group of living things generally include the suffix "-cide," meaning "to kill" (e.g., bactericide, fungicide).
FIFRA: The Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) regulates the registration, distribution, use and sale of pesticides within the United States.
Fungicides: Substances that kill vegetative fungi and some fungal spores (including blights, mildews, molds, and rusts).
Pesticide: The USEPA defines a pesticide as any substance that is intended for "preventing, destroying, repelling or mitigating any pest" or for "use as a plant regulator, defoliant or desiccant." Pests are defined as insects, rodents, worms, fungi, weeds, plants, viruses, bacteria, microorganisms and other animal life.
Biocide and Antimicrobial Chemistry
There are several general chemical classes of compounds commercially available for use as biocides. These products encompass a wide range of physical and performance characteristics. Whether a biocide is appropriate for a specific use depends on the objectives of the application; e.g., long-term preservation of a material or the need to sanitize surfaces. Therefore, adherence to label instructions is extremely important, since effective use of a biocidal or antimicrobial product depends upon proper handling; i.e., dilution concentration, pH, contact time, and condition of the surface or material to be treated (e.g., most registered products are required to be used on pre-cleaned surfaces).
Source: Chapter 8 - “Biocide and Antimicrobial Technology” - The Clean Trust Reference Guide for Professional Water Damage Restoration (The Clean Trust S500)