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Improving Mosquito Control (Adulticide) Labeling

Introduction: On Feb. 28 – Mar.1, 2001, EPA’s Region II office sponsored an Inter-Regional Mosquito Control Conference for EPA and State agency representatives. At this conference it was agreed that a work group made up of representatives of EPA’s Office of Pesticide Programs (OPP), Office of Enforcement and Compliance Assurance (OECA), EPA Regions and State lead agency volunteers would develop initial proposals for improving the clarity and enforceability of mosquito control product labels, with the focus at this time on adulticides only. The initial proposals would then be shared with a broader audience of regulatory and vector control agencies as well as pesticide registrants and other interested parties.

This paper presents the workgroup’s initial recommendations for comment and discussion by interested stakeholders. They are based on the main themes that emerged from the group’s review of a number of specific product labels which were identified as among those products most often used in public mosquito control programs. The recommendations presented here are intended to be generic recommendations for improving mosquito control product labels, and thus will have varying degrees of relevance to specific product labels now on the market.

Issue I. Mosquito control applications should be restricted to trained personnel.

Discussion: Public health vector control often involves treatment of residential areas and publically controlled lands and bodies of water. Correct use of equipment and application techniques for safe and effective treatment of such sites certainly require adequate training, but this use also requires a substantial degree of accountability to the public. For this reason, the workgroup would strongly prefer mosquito control products to be classified as Restricted Use Products (RUPs), since this is the best way States can ensure proper training and supervision of applicators as well as appropriate record-keeping.

Currently resmethrin products are federally classified as RUPs, and some States restrict other mosquito control products through State regulations. If a product is not classified as an RUP, it is still possible to limit use of the product to appropriate personnel in an enforceable manner, provided that the label language identifies a specific, verifiable group of applicators. For example, one State requires the statement “For application only by public health officials and trained personnel of Mosquito Abatement Districts”, which is enforceable (although the terms may not be appropriate for all States). It would not be effective to use a phrase that is ambiguous or subject to interpretation, such as “pest control professionals”.

Recommendation 1: Mosquito adulticides intended for public health applications should be voluntarily classified for restricted use. If not classified RUP, products should be labeled in a manner that effectively restricts use to trained personnel. For example: For use only by public health or vector control agency personnel, or persons licensed by such agencies to perform vector control, or persons certified in public health/mosquito control application.

Issue II. Many current products combine mosquito control and other uses on the same label, generating uncertainty about which directions and precautions are applicable to which uses.

Discussion: Having mosquito-control only products would solve this problem, but if that is not possible, it is essential to have clearly identified, separate sections of the label for mosquito control precautions, hazard statements and directions for use in order to avoid confusion as to which label statements apply to mosquito control use, and which do not.

Recommendation 2: Clearly distinguish and separate mosquito control directions from any other use allowed on the label.

Recommendation 3: Qualify the term “terrestrial uses” on labels by adding, after the terrestrial use statements, the statement “See separate directions and precautions for mosquito control.”

Discussion: EPA uses “terrestrial uses” on labels as a collective term for conventional agricultural and non-agricultural outdoor uses, but the term is not meant to include mosquito control, direct aquatic uses, greenhouses, indoor uses or aerial forestry applications. This information, however, is only explained in EPA’s Label Review Manual which is not readily available to product users. Thus, when the term “terrestrial uses” appears on a label followed by a series of environmental hazard precautions, it is generally not clear to users that these directions do not necessarily apply to all uses on that label. Part of the solution, as noted above, is to have separate sections of the label which clearly state the site or pests – e.g., for adult mosquitoes, for agricultural crops, for fly control, and so on, and puts both the directions for use and the appropriate precautions for that use in the same section of the label.

Issue III. Label precautions regarding applications “directly to” or “over” water are inconsistent among labels, and counterproductive in terms of effective public health applications.

Discussion: This is the single most confusing and controversial issue for mosquito control labeling, because of inconsistencies between labels, and differences of interpretation for the phrase “do not apply directly to water”. There are legal ramifications to this label statement, however, this paper does not attempt to address legal controversies. Historically, this statement was intended to apply to the agricultural and other non-mosquito control “terrestrial uses, ” and not to mosquito control directions, which were viewed as a type of aquatic use, and presumed to have their own set of aquatic precautionary statements. This point is not clear on labels themselves; it is only discussed in EPA’s Label Review Manual. Mosquito larvicides are an aquatic use, applied directly to water, but adult mosquito control is a unique use pattern which does not really fit the traditional meaning of either “terrestrial” or “aquatic” use. On the one hand, mosquito adulticide products applied as Ultra Low Volume (ULV) sprays or fogs kill the target pest by direct contact with airborne (swarming) mosquitoes, or when the insects are resting on vegetation, and both of these mosquito behaviors often occur in close proximity to bodies of water. Thus, effective targeting of the ULV sprays/fogs may require release of the pesticide over or very near a body of water, although the water itself is never the intended target. On the other hand, all the current mosquito adulticides do pose some degree of risk to aquatic organisms, and the synthetic pyrethroids are considered very toxic to aquatic life, so label precautions to warn of potential adverse effects are necessary. Debate arises over whether applications close to or over a body of water really constitute “direct application to” that body of water, because it is likely that some amount of pesticide residue, however small, will end up in the water, even though this is incidental to the intended application.

Inconsistencies among labels further complicate the issue of what aquatic precautions are appropriate. For example, some permethrin based mosquito control products have a statement not to apply the product within 100 feet of lakes or streams. This “buffer zone” was added to labels in the 1980's out of concern for aquatic toxicity, but not as a result of any actual data or assessment of risks associated with ULV mosquito control applications. (And some permethrin products for agriculture do not have a buffer zone for water, even though they are generally applied at rates 30 times greater than the ULV mosquito applications). Resmethrin product labels say “Avoid direct application over lakes, ponds and streams” (emphasis added), but the same labels state that vegetation “around stagnant pools, marshy areas, ponds and shorelines may be treated” and there is no buffer zone requirement. Other products have label warnings about hazards to aquatic organisms, but neither buffer zones nor the prohibition of “over water” applications. Naled labels do allow application over water in order to treat adult mosquitoes, blackflies or houseflies.

The workgroup reached the following conclusions about these issues. First, the statements such as “do not apply directly to water”, or “over” water, or buffer zones, are probably not very effective as precautions for protecting against hazards to aquatic life, and are definitely confusing as far as what is an allowable mosquito control application. These label statements need to be replaced by something clearer and more realistic in relation to mosquito control application practices. Second, the currently registered adulticide products have the potential to pose hazards to aquatic life, so appropriate label warnings of potential risks are needed. These warnings should be as specific as possible, consistent with available data. For example, it is preferable to say “This product is toxic to fish, shrimp and oysters” rather than “toxic to aquatic organisms”. Third, the goal of aquatic hazard statements is not to prevent absolutely any residues from ever reaching water and possibly harming some aquatic organisms. Rather, the purpose is to enable the user to recognize and minimize risks, in the context of carrying out an effective public health pest control program. In other words, some drift to water will occur from some applications, but some small degree of ecological risk should be accepted as part of the cost of protecting public health from mosquito-borne diseases with the tools now available.

Finally, the workgroup recognizes that labeling alone is not the only means of protecting the environment. State agencies often have specific information about sensitive areas in terms of species habitats, drinking water sources and other factors, and can institute additional protective measures through specific permits or other regulations. Vector control applicators need to consult state authorities to determine if permits or other regulations apply. The workgroup believes that the best initial point of contact for such inquiries is the agency that regulates pesticides. Current labels are very inconsistent in referring the user to state or federal authorities. Although the pesticide regulatory agency may not be the permitting authority, they will know if such regulations exist in their state, and who administers them.


(4). Use the following language as the standard “water precaution” for ULV adulticides, and modify current language to be consistent with it:

“Do not apply over water, except to target areas where mosquitoes are emerging or swarming, or to treat vegetation where mosquitoes may rest.”

(5) Retain all appropriate statements about potential hazards to aquatic life (and other wildlife) , and make them as specific as possible consistent with available data.

(6) Use the following statement on all adulticide labels: “Before making the first application in a season, consult with the State agency with lead responsibility for regulating pesticides to determine if permits are required.”

Issue IV. Labels need to have detailed, up-to-date, calibration instructions for ULV mosquito control applications.

Discussion/Recommendation 7: Effective use of mosquito adulticides depends on proper application rates delivered by properly calibrated equipment. Current labels vary greatly in the level of detail instructing the user how to do this. The Office of Pesticide Programs has developed recommendations for appropriate calibration instructions which should be used as a model.

Issue V. Miscellaneous clarifications.

Discussion: Current labels contain other examples of language which is vague, open to multiple interpretations, or difficult for a user to comply with. Several of these are cited below. The workgroup does not have specific recommendations for these, but welcomes suggestions on possible improvements on these or other observed problem label language.

1. “Do not contaminate water” appears on numerous labels in relation to the mixing, loading and disposal directions. Should this (and similar overly general phrases) be replaced by more specific terms such as “streams, lakes, ponds and other bodies of water”?

2. Hazards to bees. Many mosquito control products meet the criteria for a bee-hazard label statement that prohibits application when bees are visiting the treatment area. Should labels be modified to provide an exemption from that requirement in the event of a public health emergency? EPA has also raised this issue in a draft Pesticide Regulation Notice on bee hazard labeling issued for public comment in November 2000, and the idea of a public health exemption was generally supported by commenters. It should be noted, however, that most mosquito control applications, even for public health purposes like West Nile Virus, are conducted in the evenings or at night when bees are not at risk.

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