Use of disinfectants and sanitizers in heating, ventilation, air conditioning, and refrigeration systems. (Technical Briefs).

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This month's Technical Brief reprints a letter addressed to a wide range of groups that use treatment products for HVAC systems. The letter is dated March 14, 2002, and was written by Marcia Mulkey, director of the Office of Pesticide Programs at the U.S. Environmental Protection Agency (U.S. EPA). Ms. Mulkey discusses U.S. EPA's concerns about antimicrobial products used in HVAC systems.

The purpose of this letter is to bring to your attention several concerns that the agency has regarding the possible use of sanitizer and/or disinfectant products, and possibly other types of antimicrobial products, to treat the surfaces of heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, typically as part of air duct cleaning. First, although the directions for use of most of these products permit use on hard, nonporous surfaces, such directions may not specifically include the use of the product in HVAC&R systems.

We are particularly concerned about this possibility because the agency has not assessed the potential exposure and risks to building occupants or applicators from the use of these products in or on any surfaces that are part of HVAC&R systems in circumstances where the labels do not specifically authorize use in HVAC&R systems. Also, the agency has not assessed whether such products are efficacious when used in HVAC&R systems. Therefore, users cannot assume that U.S. EPA registration of these products reflects any conclusions about their safety or effectiveness in this situation. Even in circumstances where labels do list HVAC&R systems as a possible use, we are concerned that the agency has not received and reviewed data adequate to fully evaluate risks to building occupants or product efficacy in that use pattern.

An additional source of concern arises because some pesticide products also bear labels that identify the product as HVAC&R "cleaners," which could further increase the likelihood that users incorrectly make pesticidal use of such products or make incorrect assumptions about the status of U.S. EPA review, evaluation, and conclusions about them.

We believe that all these factors may contribute to possibly unlawful and/or uninformed use of these products, which could have implications for public health and safety and for consumer protection.

In the absence of adequate data and the associated review and evaluation of the registration process, use of these products in HVAC&R systems could lead to significant exposures in indoor environments with potentially unreasonable adverse effects. One indication of the potential scope of the problem is the fact that the National Antimicrobial Information Network has reported to us that it received about 150 calls related to the possible application of antimicrobial pesticide products in HVAC&R systems in a recent 18-month period.

We are writing to you because we believe you would share our concerns about the possibility that these products may be being used as pesticides in a manner not authorized by the label and not contemplated by the pesticide registration process. We also believe that you wish to ensure that these products are not being used in a manner that might be harmful to applicators and/or building occupants.

We recommend that you advise your members not to apply disinfectant, sanitizer, or other antimicrobial products to treat HVAC&R systems if such product does not include specific directions for HVAC&R use. The agency believes it is important that you ensure that members of your association are not applying products to HVAC&R systems that are not registered for that use. We intend to further evaluate this use to determine the potential exposure and risks as well as the efficacy criteria that are required before pesticide products are registered to be used in HVAC&R systems.

We recognize that it is important to address the labeling of these products, and we intend to work with pesticide registrants to ensure that these product labels clearly communicate the uses that U.S. EPA has (and has not) authorized. We also expect to ensure that appropriate evaluations of risk and effectiveness accompany any authorized uses in these systems. However, we felt it was important to inform you of these issues promptly, without waiting for any further revisions of these product labels and the conditions for their registration.

Editor's Note: For more information, readers may wish to consult the following U.S. EPA Web sites:

<http://www.epa.gov/pesticides/citizens/antimic.htm> and <http://www.ext.vt.edu/pubs/housing/356-650/356-650.html>.