Disease Reporting and Surveillance

Pyrethrin Scheduled Review

The American Horse Council submitted written comments to the Environmental Protection Agency’s (Agency) Proposed Interim Decision (PID) involving application methods for the insecticide pyrethrin and two synergists, MGK-64 (MGK) and Piperonyl butoxide (PBO).  After decades of use, we know these products to be safe, effective and absolutely essentially to the management of key insect pests in barns and animal spaces, critical to animal welfare and rider safety while in use, worker exposure is far less then presented in your documentation, and non-worker exposures are almost eliminated due the biosecurity and safety concerns ever-present at these facilities.  The AHC collaborated on comments submitted with several other entities in supporting the continued safe and wise use of these products.
Current Industry Use

Fly control in equine facilities is fundamental to the health, care and use of the animals present. Pyrethrins used with the synergists, PBO or MGK-264, ( pyrethrin +) is the core foundation of many of the fly control programs in use today at animal agriculture facilities.  This is because pyrethrin + is the most effective option available, and has decades of use history proving its safety and efficacy.

These are the most effective and safe products for controlling the adult fly populations without the potential for development of resistance.  Other products or IPM tools are used in conjunction with pyrethrin + to control insects, but all IPM’s in the US equine industry utilize pyrethrin+ products in a method your PID eliminates. In cases of the federally regulated diseases Equine Infectious Anemia, Vesicular Stomatitis, and Equine Piroplasmosis, USDA protocols require vector mitigation measures including direct application of insecticides labeled for use on horses be implemented as part of the disease response. The American Association of Equine Practitioners’ ectoparasite guidelines for veterinarians recommend pyrethrins and/or PBO as the most widely available products for safe and effective control of ectoparasites on horses.

The most common modes of application in the equine industry are through trigger pump sprayers and misting systems. Misting and spraying methods of application are essential due to the nature of equine behavior, human-horse interactions, and methods of housing/care. Trigger pump sprayers are a ubiquitous component of our industry that stands alone in its place as a critical part of IPM. Horses are easily frightened, and have to be trained at an early age to accept trigger pump spray bottles, and are not as ready to acclimate to other methods of application. Large sprayers, aerosols and wipes are quite triggering for horses, and as such have not found a foothold in our IPM models.

Misting systems are growing in use throughout the animal agriculture due to their lower application costs, reduced labor requirements,  and the flexibility and precision they allow in application times, locations and amounts. These systems have been in place within the horse industry for decades. These systems effectively limit human exposure to the pyrethrin + by limiting the amount of hand application.  The protections provided by these systems is critical to the usefulness of our industry’s infrastructure.

Pyrethrin + works quickly and has been used for decades without indications of resistance development, and it degrades rapidly without leaving any problematic residue to further increase the risks of resistance developing.  The alternative products available and labeled for these uses are either far less effective, require several more applications, or  would inevitably drive resistance among the adult fly breeding population. The common IPM methods in use today often involve the use or encouragement of beneficial parasitic wasps at facilities; pyrethrin + is used because it provides adult fly control where the product quickly degrades with no surface residue reducing or eliminating risks to the wasp population.

Worker Exposure

We contend that EPA’s assumptions for material handled in treating horses is a large over-estimate. In EPA’s revised assessment, we also note that ‘veterinary/groomer’ scenario does not pose any occupational risks of concern. We contend that even though two bottles per day is already a large over-estimate on typical usage, this use pattern is more in line with the typical practices of horse owners than the direct animal treatment assumptions of 30 animals treated per day at a rate of 0.03 lbs ai/animal for pyrethrin+. This estimate far exceeds any reasonably likely treatment scenarios for horse caretakers due to practical time constriction associated with the work of trainers, caretakers, or other boarding stable employees working with horses. Most caretakers would not have time to treat (and work) more than 5-6 horses per day.

Further, the amount of material applied per animal would never approach 0.03 lbs ai of pyrethrin+ for all animals, much less single animals. An average consumer intended 32 oz spray bottle (of a 0.1% pyrethrin+ product) results in use of about 0.5 fluid ounces of product per horse per day. This estimate corresponds to 0.0003 lbs pyrethrin+ applied per animal. Even assuming a 5 times stronger product being used (0.5% pyrethrin+) yields an estimate of 0.0015 lbs ai applied per animal. This means that EPA’s estimate of 0.03 lbs ai/animal for pyrethrin+ is between 20-fold and 100-fold higher than actual application rates used by animal caretakers for direct daily treatments to horses.

No workers in any horse boarding or care facilities would be treating more than 5-6 animals per day, noting that simultaneous treatments of >10 animals per day would instead be done using automated barn misting systems, which will be discussed in more detail later in our comments. Traditional daily care of a horse that includes application of pyrethrin+ would also include the use or exercise of that animal, which would limit the opportunity to interact with and treat more than 5-6 animals per day.

We contend that between EPA’s large over-estimates on handling assumptions for workers treating horses (both in the number animals assumed treated per day and pounds ai of pyrethrin+ assumed to be applied per animal) and the very high benefits associated with such products, EPA would be well-supported in retaining the use of trigger pump spray bottle products for use on horses without additional mitigation. However, if still EPA believes that some form of mitigation will be needed, stakeholders noted that a reasonable handling limitation on labels (e.g., “do not apply more than one bottle per day of this product”) would be workable and practical for horse caretakers and allow for continued access to these critically important products.

Numerous products registered for residential use, including pyrethrins-based total release foggers, contain label statements that protect both users and bystanders. In discussion with retail product manufacturers, several are amiable to similar label statements requiring product use in well-ventilated areas would be practical and workable for use on pyrethrin+ trigger spray bottle products used by horse owners.

More generally, we recognize that horse owners already use a wide variety of FDA-labeled animal care and veterinary products and assume numerous occupational risks in the ownership and care of horses. We suggest that for practical purposes, spray-bottle pesticide applications to horses fall clearly within the realm of occupational exposure and not residential exposure, though we understand the sensitivities and legal uncertainties this space presents to EPA.

Bystander Exposure in Stables

It is widespread practice in all large equine operations to practice strict biosecurity practices.  It is extremely rare for any person not working at a facility to be allowed entry into a building, and if it happens it is only under controlled circumstances that involve staff supervision.  A critical issue facing our industry’s facility management includes the risk to bystanders presented by the animals often erratic behavior. Liability concerns surrounding bystander safety have fundamentally change the relationship horse owners have with the general public, and the extends to allowing bystanders within the immediate area surrounding an animals reach, which is significant. Any estimates of non-worker exposure to the pyrethrin + products used in the animal houses should take these points into account.

Conclusion

The PID mentions the EPA’s conclusion that cancellation of these products would not result in significant loss of efficacy or economic impacts for users. We empathically disagree with this assumption and we have successfully relayed our concerns. The comments received by the EPA resulted in their decision to delay any decision until 2024.

Health Canada, the Canadian equivalent of the EPA, has now banned indoor structural broadcast applications to control flies and mosquitoes in livestock and poultry housing facilities and pressurized products used in metered-release devices. While this has no direct effect on US regulations, there is concern this may set an international precedent for a 2024 EPA decision.

The AHC will continue to work with the industry, the USDA and the larger Livestock industry to prevent this critical product from being taken away from horse owners, riders and caregivers.

Proposed Regulation of PFOA and PFOS as CERCLA Hazardous Substances

In fall of 2022 the EPA released a notice of proposed rulemaking to designate PFOA and PFOS as CERCLA Hazardous Substances. The Comprehensive Environmental Response, Compensation, and Liability Act, aka CERCLA or “Superfund”, authorizes the EPA to specify substances as hazardous and would require facilities across the country to report any PFOA or PFOS above the designated threshold and hold them liable for all costs associated with the clean up.

While this was not brought to the attention of the AHC until after the comment period has closed, many comments were submitted on behalf of agriculture stakeholders.

What are PFOA/PFOS, and where are they found?

PFOA or PFOS, are known as “forever chemicals. They are ubiquitous in everyday commercial products such as waterproofed clothing (and horse blankets), nonstick cooking products, firefighting foam, and more. Scientific studies have shown that exposure to PFAS in the environment may be linked to harmful health effects in humans and animals.

Because there are thousands of different PFOA/PFOS chemicals, and they are found in so many different consumer, commercial, and industrial products, it is challenging to study and assess the potential human health and environmental risks. It is not yet fully understood what level of PFOA/PFOS exposure is unsafe, and what the long-term health impacts may be.

PFOA/PFOS initially entered the environment through manufacturing and disposal processes and ultimately ended up in human and animal drinking water. This has created a cycle where the PFOA/PFOS are then consumed and excreted through waste, then further absorbed into the water table and also potentially into plants and livestock, once again re-entering the human food chain. PFOA/PFOS contamination has been found on every continent, in the ocean, in the soil, in snowflakes and raindrops, and in human fetal cells.

Unbeknownst to farmers, sludge and fertilizer from wastewater treatment plants were not able to filter out PFOA/PFOS, resulting in it being spread onto crops and pasture lands during routine field work.

PFOA/PFOS Thresholds, Testing, and Impacts of a CERCLA Ruling

In March 2023 the EPA released proposed thresholds for PFOA/PFOS found in water and soil. These thresholds are considered extremely low and currently are set below what is considered testable levels.

Several states, including Maine and New Mexico have set requirements for PFOA/PFOS levels that have resulted in some farms being shut down for contamination. There is concern that federal CERCLA designation with levels held to the current recommended thresholds would cause many farms to be designated Superfund sites and forced to shut down.

A coalition of agriculture stakeholders, including the AHC, is consulting with parties experienced in CERCLA designations to delay this ruling and encourage the EPA to prioritize research associated with PFOA/PFOS safety thresholds and appropriate cleanup strategies. The coalition is also working to encourage the EPA to provide an agricultural exemption. The EPA has announced a final decision will be made by August 2023.

Environmental Regulations and Large-Scale Equine Facilities.

Over the last several years the American Horse Council has been monitoring situations involving long-term/permanent equine holding facilities and the pressures placed on them due to environmental regulations in their state. California, in particular, has placed undue pressure on equine facilities bordering waterways, to the degree that several facilities may close down. Water Management and Environmental Protection laws in these cases are the product of state regulatory action. The singular Federal language of note used in the enforcement of these regulations concerns the definition of a concentrated animal feeding operation, or CAFO. CAFO’s are described as small, medium, or large, with large facilities being designated as permanently housing 500 animals or more throughout the year.

As state regulations change the environmental needs of communities in rural areas, oftentimes large CAFOs are expected to meet waste management, water runoff, and large-scale infrastructure requirements that are uncommon and often unnecessary to meet the needs of equine operations. Unfortunately, the designation of large CAFOs is unlikely to be changed at the federal level. As such, the horse industry needs to take active action at the state level to prevent burdensome regulatory action or pursue equine specific exemptions in States with existing environmental regulations.

AHC staff have taken steps to prioritize the development of strategies and actions that can be taken on behalf of the industry at large. This includes educational materials for horse owners and peer organization outreach to raise awareness of the hostile actions being taken by environmental groups towards agricultural interests.

The American Horse Council will continue to monitor the situation and facilitate what actions can be taken in Washington DC.