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| | Fig. 3 Self-contained chemical treatment is a way to keep waterlines clean. |
The CDC has stated, “Exposing patients or dental health care personnel to water of uncertain microbiological quality, despite the lack of documented adverse health effects, is inconsistent with generally accepted infection control principles.”4
There are several approaches to improving the quality of dental unit water. These include:
• Installing a microbial filter close to the end of the waterline;
• Disconnecting from city water and installing a self-contained water system bottle (Fig. 3) that can supply special treatment water and allows for delivery of chemical treatments;
• Purifying the incoming water by a method that kills or removes microbes (e.g., filtration, high heat, UV light). This approach is associated with treatments that attack the biofilm.
Dental Products Report magazine and Web site have included products dealing with dental unit waterlines asepsis. The ADA also lists several water quality products.5
In summary, the EPA has set standards to help ensure safe drinking water in the United States. The CDC and ADA recommend that these drinking water standards be used in dentistry to help assure the safety of water used in dental treatment. Dental units that have not been treated to reduce microbial contamination in the waterlines likely do not provide water that is of drinking quality.
Chris H. Miller, PhD, is Professor Emeritus of Oral Microbiology and Executive Associate Dean Emeritus at Indiana University School of Dentistry, Indianapolis. Dr. Miller may be reached via e-mail at either chmille@iupui.edu or c/o ewhite@advanstar.com.
The Environmental Protection Agency (EPA) offers standards to help ensure safety and potability of water in the United States.2
After reviewing health effects studies, EPA sets a Maximum Contaminant Level Goal (MCLG), the maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur. This allows an adequate margin of safety.
After determining the MCLG, EPA sets an enforceable standard. In most cases, the standard is a Maximum Contaminant Level (MCL), the maximum permissible level of a contaminant in water that is delivered to any user of a public water system.
When no reliable economically or technically feasible method exists to measure a contaminant at particularly low concentrations, a Treatment Technique (TT) is set instead of an MCL. A TT is an enforceable procedure or level of technological performance that public water systems must follow to ensure contaminant control.
Besides setting drinking water MCLs or TTs for at least 80 organic and inorganic chemicals, the EPA also has established standards for microbial contaminants.
For microbial contaminants that present a potential public health risk, the MCLG is set at zero, for ingesting just one protozoan, virus, or bacterium may adversely affect health. The EPA currently is studying whether a safe level above zero exists.
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