Document ID: EPA-HQ-OPP-2019-0035-0011
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2020-08-26T04:00Z

Pyroxsulam
                                       
                     Interim Registration Review Decision
                               Case Number 7275
                                       
                                       
                                   June 2020
                                       
                                       
                                       
                                                                   Approved by:
  

Elissa Reaves, Ph.D.

Acting Director

Pesticide Re-evaluation Division
                                                                          Date:
      06-26-2020

Table of Contents

I.	INTRODUCTION	3
A.	Updates since the Proposed Interim Decision was Issued	4
B.	Summary of Pyroxsulam Registration Review	4
C.	Summary of Public Comments on the Combined Work Plan and Proposed Interim Decision	5
II.	USE AND USAGE	6
III.	SCIENTIFIC ASSESSMENTS	6
A.	Human Health Risks	6
1.	Human Incidents and Epidemiology	7
2.	Tolerances	7
3.	Human Health Data Needs	8
B.	Ecological Risks	8
1.	Risk Summary and Characterization	8
2.	Ecological Incidents	9
3.	Ecological and Environmental Fate Data Needs	9
C.	Benefits Assessment	10
IV.	INTERIM REGISTRATION REVIEW DECISION	10
A. Risk Mitigation and Regulatory Rationale	10
B. Tolerance Actions	15
C. Interim Registration Review Decision	16
D. Data Requirements	16
V.	NEXT STEPS AND TIMELINE	16
A.	Interim Registration Review Decision	16
B.	Implementation of Mitigation Measures	16
Appendix A:  Summary of Required Actions for Pyroxsulam	18
Appendix B: Required Labeling Changes for Pyroxsulam Products	19

 

 INTRODUCTION
	
This document is the Environmental Protection Agency's (the EPA or the agency) Interim Registration Review Decision (ID) for pyroxsulam (PC Code 108702, case 7275), and is being issued pursuant to 40 CFR §§ 155.56 and 155.58. A registration review decision is the agency's determination whether a pesticide continues to meet, or does not meet, the standard for registration in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The agency may issue, when it determines it to be appropriate, an interim registration review decision before completing a registration review. Among other things, the interim registration review decision may require new risk mitigation measures, impose interim risk mitigation measures, identify data or information required to complete the review, and include schedules for submitting the required data, conducting the new risk assessment and completing the registration review. Additional information on pyroxsulam, can be found in the EPA's public docket (EPA-HQ-OPP-2019-0035) at www.regulations.gov.
 
FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandates the continuous review of existing pesticides. All pesticides distributed or sold in the United States must be registered by the EPA based on scientific data showing that they will not cause unreasonable risks to human health or to the environment when used as directed on product labeling. The registration review program is intended to make sure that, as the ability to assess and reduce risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard of no unreasonable adverse effects. Changes in science, public policy, and pesticide use practices will occur over time. Through the registration review program, the agency periodically re-evaluates pesticides to make sure that as these changes occur, products in the marketplace can continue to be used safely. Information on this program is provided at http://www.epa.gov/pesticide-reevaluation. In 2006, the agency implemented the registration review program pursuant to FIFRA § 3(g) and will review each registered pesticide every 15 years to determine whether it continues to meet the FIFRA standard for registration.

The EPA is issuing an ID for pyroxsulam so that it can (1) move forward with aspects of the registration review that are complete and (2) implement interim risk mitigation (see [Appendices A and B]). The agency is currently working with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (collectively referred to as, "the Services") to develop methodologies for conducting federally threatened and endangered (listed) species assessments for pesticides in accordance with the Endangered Species Act (ESA) § 7. Therefore, although the EPA has not yet fully evaluated risks to federally-listed species, the agency will complete its listed species assessment and any necessary consultation with the Services for pyroxsulam prior to completing the pyroxsulam registration review. Likewise, the agency will complete endocrine disruption screening for pyroxsulam, pursuant to the Federal Food, Drug, and Cosmetic Act (FFDCA) § 408(p), before completing registration review.

The first product containing pyroxsulam was registered with EPA in 2008. Products containing pyroxsulam are used as a systemic post-emergence (to the weed) herbicide intended for control of a broad spectrum of annual grasses and broadleaf weeds in wheat (spring, winter, and durum) and triticale by ground and aerial application. Currently, there are 12 registered end-use products containing pyroxsulam.  
This document is organized in five sections: Introduction, which includes this summary and a summary of public comments and the EPA's responses; Use and Usage, which describes how and why pyroxsulam is used and summarizes data on its use; Scientific Assessments, which summarizes the EPA's risk and benefits assessments, updates or revisions to previous risk assessments (if any) and provides broader context with a discussion of risk characterization; the Interim Registration Review Decision, which describes the mitigation measures required to address risks of concern and the regulatory rationale for the EPA's interim decision (ID); and, lastly, the Next Steps and Timeline for completion of this registration review.

 Updates since the Proposed Interim Decision was Issued

In February 2020, the EPA published the combined Work Plan and Proposed Interim Registration Review Decision (PID) for pyroxsulam. In this ID, there are no updates to mitigation measures proposed in the PID. Please see the response to comments in Section I.C of this document for more detail.

 Summary of Pyroxsulam Registration Review

Pursuant to 40 CFR § 155.50, the EPA formally initiated registration review for pyroxsulam with the opening of the registration review docket for the case. The following summary highlights the docket opening and other significant milestones that have occurred thus far during the registration review of pyroxsulam.  

 February 2020 - The agency posted the combined Work Plan and Proposed Interim Registration Review Decision for pyroxsulam to the public docket for a 60-day public comment period, which ended on April 6, 2020. Along with the combined Work Plan and PID, the following documents were also posted to the pyroxsulam docket: 
   
 Pyroxsulam. Combined Scoping Document/ Draft Risk Assessment for Registration Review, dated September 25, 2019
 Pyroxsulam: Problem Formulation, Draft Ecological Risk Assessment and Human Health Drinking Water Assessment for Registration Review, dated September 26, 2019
 Pyroxsulam: Tier I (Scoping) Review of Human Incidents and Epidemiology, dated August 13, 2019.
 Pyroxsulam (108702) Screening Level Usage Analysis (SLUA), dated May 21, 2019.
         
 June 2020  -  The agency completed the ID and will announce its availability in the Federal Register Notice afterwards. 

   
Summary of Public Comments on the Combined Work Plan and Proposed Interim Decision

During the 60-day public comment period for the pyroxsulam PID, which opened on February 4, 2020 and ended on April 6, 2020, the agency received public comments from three sources (US Department of Agriculture (USDA), National Agricultural Aviation Association (NAAA), and a private citizen). The agency thanks all commenters for their comments. Substantive comments, comments of a broader regulatory nature, and the agency's responses to those comments are summarized below. 

Comment Submitted by USDA (Docket ID: EPA-HQ-OPP-2019-0035-0008)

Comment: USDA agreed with the agency's finding that pyroxsulam is an important herbicide for its control of annual weeds in winter wheat and can provide greater than 90 % control of problematic annual grasses along with the annual broadleaf weeds. The USDA also agreed with the standardized spray drift restrictions proposed and the selection of nozzles and pressure that deliver medium or coarser droplets. The USDA submitted additional efficacy data in support of pyroxsulam and agreed with the inclusion of herbicide resistance management language on pyroxsulam labels. 

EPA Response: The agency thanks USDA for its comments and submission of efficacy data. The agency is taking effective mitigation steps for spray drift management and herbicide resistance management by incorporating the languages on the label included in this ID. For more information on the mitigation for pyroxsulam, see Section IV of this document. 

Comment Submitted by NAAA (Docket ID: EPA-HQ-OPP-2019-0035-0009)

Comment: NAAA supports the proposed spray drift language for aerial applications in the PID for pyroxsulam. The NAAA recommended that the proposed label language which states, "Do not apply during temperature inversions," be amended to "Do not apply during low-level temperature inversions." The reason for NAAA's recommendation is that there are often temperature inversions at higher altitudes, well above where the application is being made. These high-altitude temperature inversions have no impact on pesticide applications but could cause confusion when it comes to label enforcement. Only low-level temperature inversions near the ground and within the application zone will impact pesticide drift. 

EPA Response: The agency thanks the NAAA for its comments. Given the difficulty of defining the altitude where inversion conditions may not impact drift, the EPA believes the terms "high-level" and "low-level" do not provide adequate clarification. The label language for temperature inversions that the EPA proposed in the pyroxsulam PID is the standard language that the agency requires to ensure consistency across all cases. Therefore, in this ID, the EPA is requiring the temperature inversion label statements proposed in the PID, without any modifications.

 USE AND USAGE

Pyroxsulam is a systemic post-emergence (to the weed) herbicide intended for control of a broad spectrum of annual grasses and broadleaf weeds in wheat (spring, winter, and durum) and triticale by ground and aerial application. Pyroxsulam is a triazolopyrimidine sulfonamide herbicide. The Weed Science Society of America (WSSA) places this chemical in Mechanism of Action Group 2. Members of this group suppress the plant enzyme acetolactate synthase (ALS), which is essential for the synthesis of certain amino acids. Inhibition of the production of these amino acids subsequently prevents cell division and causes death in susceptible plants.
From 2008-2017, about 8,000 pounds of pyroxsulam were applied annually to spring wheat and about 11,500 pounds are applied to winter wheat. This usage accounts for ten percent of crop treated in spring wheat and five percent of crop treated in winter wheat. Most pyroxsulam applications are for post-emergence control of cheat (Bromus tectorum), wild oat (Avena fatua), kochia (Bassia scoparia), wild buckwheat (Eriogonum spp.), foxtail (Setaria pumila), and downy brome (Bromus tectorum). The majority of pyroxsulam (approximately 90% of the total pounds applied per year) used in wheat is applied in Montana, North Dakota, South Dakota, Washington, Oklahoma, Idaho, and Kansas.3

The EPA does not have usage data for triticale.

For more details, see the supporting document, Pyroxsulam (108702) Screening Level Usage Analysis (SLUA), dated May 21, 2019, which is available in the public docket for pyroxsulam (EPA-HQ-OPP-2019-0035) at http://www.regulations.gov.  	

SCIENTIFIC ASSESSMENTS

 Human Health Risks 

A summary of the agency's human health risk assessment is presented in the PID. The agency used the most current science policies and risk assessment methodologies to prepare a risk assessment in support of the registration review of pyroxsulam. 

There were no dietary, aggregate or occupational risks of concern. There are no registered residential uses of pyroxsulam, and therefore a residential assessment was not conducted. The human health risk conclusions for pyroxsulam have not changed since the PID, and no further human health data are expected to be needed for this registration review.

For additional details on the human health assessment for pyroxsulam, see the Pyroxsulam. Combined Scoping Document/Draft Risk Assessment for Registration Review, which is available in the public docket.

 Human Incidents and Epidemiology
Both the OPP Incident Data System (IDS) and the Centers for Disease Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) Sentinel Event Notification System for Occupational Risk-Pesticides (SENSOR) databases were consulted for pesticide incident data on the active ingredient pyroxsulam. The IDS records incidents in one of two modules: Main IDS and Aggregate IDS. The purpose of the database search is to identify potential patterns in the frequency and severity of the health effects attributed to pyroxsulam exposure. Pyroxsulam is not included in the Agricultural Health Study (AHS). 

For the seven years from January 1, 2012 to July 18, 2019, there were three incidents reported in the Main IDS that involved the active ingredient pyroxsulam. All of these incidents involved multiple active ingredients and were classified as moderate severity. For the same time period, there were 10 incidents reported in the Aggregate IDS that involved pyroxsulam. These incidents were classified as minor severity. A query of SENSOR-Pesticides from 2010-2015 identifies no cases involving pyroxsulam.
 
Based on the low frequency and severity of pyroxsulam incidents reported to both IDS and SENSOR-Pesticides, there does not appear to be a concern at this time. The agency will continue to monitor the incident information. Additional analyses will be conducted if ongoing human incident monitoring indicates a concern.

 Tolerances

Tolerances are established for residues of pyroxsulam, including its metabolites and degradates, in or on the commodities listed under 40 CFR §180.638. Compliance with the tolerance levels is to be determined by measuring only pyroxsulam, N-(5,7-dimethoxy[l, 2,4]triazolo[l, 5-a]pyrimidin-2-yl)-2-methoxy-4-(trifluoromethyl)-3-pyridinesulfonamide, in or on the commodity. 

There are no issues with international harmonization of tolerances for pyroxsulam. Codex has not established any maximum residue limits (MRLs) for pyroxsulam; Canada's only MRL for pyroxsulam is on wheat grain and is harmonized with the United States.

 Human Health Data Needs

The agency does not anticipate any further human health data needs for the registration review of pyroxsulam. 

Ecological Risks

A summary of the agency's ecological risk assessment is presented below. The agency used the most current science policies and risk assessment methodologies to prepare a streamlined risk assessment in support of the registration review of pyroxsulam. For additional details on the ecological assessment for pyroxsulam, see the Pyroxsulam: Problem Formulation, Draft Ecological Risk Assessment and Human Health Drinking Water Assessment for Registration Review, which is available in the public docket.

The EPA is currently working with its federal partners and other stakeholders to implement an approach for assessing potential risk to federally listed species and their designated critical habitats. Once the scientific methods necessary to complete risk assessments for listed species and their designated critical habitats are finalized, the agency will complete its endangered species assessment for pyroxsulam.

Risk Summary and Characterization

The agency concluded that the current registrations containing pyroxsulam present no risks of concern to the following taxa: freshwater fish, estuarine/marine fish, amphibians (aquatic phase), freshwater invertebrates, aquatic plants, birds, and mammals. Although no toxicity data are available with which to assess acute or chronic risk to estuarine/marine animals, the likelihood of adverse effects for estuarine/marine fish and invertebrates is low.

Terrestrial Invertebrates (honeybees) 

As discussed previously, pyroxsulam is a systemic post-emergent herbicide for control of a broad spectrum of annual grasses and broadleaf weeds in wheat. While wheat is not considered pollinator-attractive, exposure of bees foraging on flowering plants/weeds adjacent to the treated crop is possible. Acute oral and contact toxicity data for adult honeybees are available and indicate that the compound is practically nontoxic to adult bees, with risk quotient (RQ) values below the acute risk level of concern (LOC). There are also no bee-related incidents associated with the use of the compound. However, other than the acute toxicity data for adult honeybees, the remaining suite of Tier 1 honeybee (Apis mellifera) toxicity data (see Table 1 below) are not available for pyroxsulam. Therefore, there are uncertainties regarding the acute and chronic toxicity to larval honeybees and the chronic toxicity to adult honeybees of pyroxsulam. Additional data may be necessary to fully evaluate potential risks to terrestrial invertebrates. 

Table 1: Potential Honeybee (Apis mellifera) Data Requirements.

Guideline #
Study
                                    Tier 1
Non-Guideline (OECD TG 237)
Honeybee larvae acute oral toxicity 
Non-Guideline (OECD TG 245)
Honeybee adult chronic oral toxicity 
Non-Guideline (OECD GD 239)
Honeybee larvae chronic oral toxicity 
                                  Tier 2[†]
Non-Guideline
Field trial of residues in pollen and nectar (tunnel or colony feeding studies)
Non-Guideline (OECD GD 75)
Semi-field testing for pollinators  
                                  Tier 3[†]
OCSPP 850.3040
Full-Field testing for pollinators  
OECD=Organization for Economic Cooperation and Development; TG=Test Guideline; GD=Guidance Document
[†] The need for higher-tier tests for pollinators will be determined based upon the results of lower-tiered tests and/or other lines of evidence and the need for a refined pollinator risk assessment.

Terrestrial Plants

The ecological risk assessment identified potential risks of concern for terrestrial monocotyledonous (monocot) and dicotyledonous (dicot) plants in dry areas and semi-aquatic areas via runoff and through spray drift with the RQ exceeding the LOC of 1 for risk to plants. Estimated risks may translate to indirect risks of reduced survival, reproduction, or growth on animals that depend on plants for food and habitat. Monocots appear more sensitive to pyroxsulam with RQs ranging from 0.75 to 41 compared to 1.7 to 16 for dicots. 

 Ecological Incidents

A search of the IDS on September 26, 2019 showed no reported incidents associated with the use of pyroxsulam since registration of the first product containing pyroxsulam. It is important to note though that the absence of incident reports cannot be construed as the absence of incidents. The agency will continue to monitor ecological incident information as it is reported to the agency. Detailed analyses of these incidents are conducted if reported information indicates concerns for risk to non-target organisms.

 Ecological and Environmental Fate Data Needs

While there are some uncertainties highlighted in the 2007 risk assessment with the submitted anaerobic and aerobic aquatic metabolism studies and terrestrial field dissipation studies, additional data are not expected to significantly alter risk conclusions at this time. Although no toxicity data were submitted for estuarine/marine animal species, the toxicity profile based on freshwater species and the physical properties of the chemical indicate that the likelihood of risks of concern for estuarine/marine species is low and that the toxicity data are not recommended at this time.

Given the uncertainties surrounding potential risks to terrestrial invertebrates, additional data may be necessary to fully evaluate potential risks to bees. The EPA will consider requiring submission of pollinator data (as described in Table 1) as a separate action.

Benefits Assessment
Pyroxsulam provides selective postemergence control of grass and broadleaf weeds in winter and spring wheat varieties (including durum) and triticale over a wide application window starting in early fall through mid-spring. Uncontrolled population of annual weeds can compete with grain crops throughout the year, resulting in a slow rate of crop development and potentially reducing yields. Weeds treated with pyroxsulam cease nutrient uptake almost immediately providing a quick reduction in competition between the weed and crop. In addition, pyroxsulam can be safely applied to a wide window of actively growing wheat stages, including 3-leaf stage up to jointing stage. 

INTERIM REGISTRATION REVIEW DECISION

    A. Risk Mitigation and Regulatory Rationale 

In evaluating potential risk mitigation for pyroxsulam, the EPA considered the risks, the benefits, and the use pattern of this compound. The agency did not identify any potential human health risks of concern for pyroxsulam when used as directed on current labels. As discussed in the Ecological Risk Section of this document, the agency identified risks to non-target terrestrial plants from spray drift. To address the risks to non-target terrestrial plants, the agency is requiring mandatory and advisory spray drift language. To reduce the potential risks of concern, the agency is also requiring advisory language for surface water and ground water along with the updated label language for gloves. 

For pyroxsulam, the EPA is taking the same approach to risk management as it did with the other ALS-inhibitors. Requiring risk mitigation similar to other ALS-inhibitors was both convenient and logical from a regulatory perspective because they exhibit a common herbicidal mechanism of action, show similar ecological effects, and predominantly pose risks to terrestrial plants. 

The technical registrant, Corteva Agriscience, formerly Dow Chemical Company, has agreed in principle to the required risk mitigation measures to address potential risk concerns from pyroxsulam.

 Updated Glove Statements
   
The agency is requiring an update to the glove statements currently on labels to be consistent with Chapter 10 of the Label Review Manual. The required new glove language does not fundamentally change the personal protective equipment that workers need to use, and therefore should impose no impacts on users.

All statements that refer to the chemical resistance category selection chart are required to be removed from pyroxsulam labels, as they might cause confusion for users. These statements are required to be replaced with specific chemical-resistant glove types, as appropriate. This minor clarification does not fundamentally change the personal protective equipment that workers are currently required to use.

 Spray Drift Management

The agency is requiring label changes to reduce off-target spray drift and establish a baseline level of protection against spray drift that is consistent across all pyroxsulam products. Reducing spray drift will reduce the extent of environmental exposure and risk to non-target plants and animals. Although the agency is not making a complete endangered species finding at this time, these label changes are expected to reduce the extent of exposure and may reduce risk to listed species whose range and/or designated critical habitat co-occur with the use of pyroxsulam.  

The agency is requiring the following mandatory spray drift mitigation language to be included on all pyroxsulam product labels for products applied by liquid spray application. The required spray drift language is intended to be mandatory, enforceable statements and supersede any existing language already on product labels (either advisory or mandatory) covering the same topics. The agency is providing recommendations which allow pyroxsulam registrants to standardize all advisory language on pyroxsulam product labels. Registrants must ensure that any existing advisory language left on labels does not contradict or modify the new mandatory spray drift statements required in this ID, once effective.

 Applicators must not spray during temperature inversions for ground and aerial applications.
 For aerial applications, do not apply when wind speeds exceed 15 mph at the application site. If the windspeed is greater than 10 mph, the boom length must be 65% or less of the wingspan for fixed wing aircraft and 75% or less of the rotor diameter for helicopters. Otherwise, the boom length must be 75% or less of the wingspan for fixed-wing aircraft and 90% or less of the rotor diameter for helicopters.
 For aerial applicators, if the windspeed is 10 miles per hour or less, applicators must use (1/2) swath displacement upwind at the downwind edge of the field.  When the windspeed is between 11-15 miles per hour, applicators must use (3/4) swath displacement upwind at the downwind edge of the field.
 For aerial applications, the release height must be no higher than 10 feet from the top of the crop canopy or ground, unless a greater application height is required for pilot safety.
 For ground boom applications, users must only apply with the release height recommended by the manufacturer, but no more than 3 feet above the ground or crop canopy.
 For ground and aerial applications, select nozzle and pressure that deliver medium or coarser droplets as indicated in nozzle manufacturers' catalogues and in accordance with American Society of Agricultural & Biological Engineers Standard 572.3 (ASABE S572.3).
 For ground boom applications, do not apply when wind speeds exceed 15 mph at the application site.
                                                                               
The agency is requiring a restriction on droplet size, because coarser droplets have been demonstrated to decrease spray drift, and therefore, reduce potential risks to non-target species. 

In addition to including the spray drift restrictions on pyroxsulam labels, all references to volumetric mean diameter (VMD) information for spray droplets are required to be removed from all pyroxsulam labels where such information currently appears. The required new language above, which cites ASABE S572.3, eliminates the need for VMD information. 

The agency acknowledges that there will be impacts to growers from spray drift restrictions. Potential impacts are discussed below.

Droplet Size

In general, potential negative impacts to growers from requiring larger droplets could include reductions in efficacy, increased selection pressure for the evolution of herbicide resistance due to a decrease in lethal dose delivered to target weeds, increased application rates used by growers, increased costs associated with reduced yield, more herbicide applications, purchase of alternative products, or an inability to use tank mix or premix products. Because chemical-specific data for the performance of droplet size is limited, the EPA was not able to evaluate the effects of medium or coarser droplet sizes (as defined by ASABE S572.3) specifically for pyroxsulam. Therefore, the EPA does not know the effect this requirement will have on the performance of pyroxsulam across various use patterns. However, pyroxsulam is a systemic herbicide, so full foliar coverage is not necessary to maintain efficacy; thus, mandating a droplet size of medium or coarser is unlikely to have an impact on efficacy.
      

Wind Speed (aerial and ground applications)

The agency considers that it is a "good application practice" that growers apply herbicides at 15 mph or less. However, products containing pyroxsulam currently do not have wind speed instructions, so growers have the flexibility to spray in any situation. Mandatory wind speed restrictions may complicate weed and crop management by reducing the available time to make applications and making growers more likely to alter weed control plans. 

A narrower window of application could lead to different issues. Once the window of application passes for either the crop or weed, the weeds may be too large to be adequately controlled by pyroxsulam, which could accelerate the development of resistance, or there may be phytotoxicity issues at the later crop stage, either of which could reduce yields. 

Alternatively, a grower may develop another weed control strategy. However, changing plans may be more costly if a different, more expensive herbicide(s) is used, or if multiple applications are needed to achieve the same level of weed control as pyroxsulam. 

Additionally, growers are likely to incur higher costs if they hire a custom applicator. Although growers are not likely to purchase new equipment mid-season, growers eventually may need to purchase additional spray equipment to ensure they are able to make timely applications. In addition to a new sprayer, a grower would have to hire additional personnel to operate the sprayers to make applications in a timely manner. If applications were not made in a timely manner, weed control could decline, leading to additional herbicide applications and/or yield losses. 

Temperature Inversions, Release Height, Boom Length, and Swath Displacement (aerial applications)

The agency does not expect impacts from prohibitions regarding applications during a temperature inversion; nor from a requirement of a release height no higher than 10 ft from the top of the crop canopy or ground, unless a greater application height is required for pilot safety. Products containing pyroxsulam that account for more than 90% of the chemical's use already contain these restrictions.

Requiring that the percent of usable boom length be reduced from 10-15% at windspeeds between 10 and 15 mph, depending on the type of aircraft, would increase the number of passes made when treating a field. This would increase the amount of time needed to treat a field and likely increase the cost of application. When windspeeds were less than 10 mph, there would be no change for fixed-wing aircraft, and, therefore no impact.  When applying with an aircraft with rotor blades at 10 mph or less, there would be increased percent usable boom length (90% or less) which could mean more area can be covered in less time.

The agency has not assessed the impacts of windspeed restrictions for aerial applications and the requirement of a (1/2) or (3/4) swath displacement upwind at the downwind edge of the field. The agency did not receive any comment on the impact to growers regarding these requirements. 

Temperature Inversions and Release Heights (ground applications)

The requirement to not apply during temperature inversion could reduce the amount of time users have to apply pyroxsulam. Users may switch to other products that only have advisory language for this restriction if they encounter temperature inversions when needing to treat a field.

Previous analysis for release heights of most nozzles indicate a release height of 4 ft should not impact growers when making pesticide applications, but a release height less than 4 ft could have negative impacts on growers due to the relationship between nozzle spacing and release height.  The agency has no information on the percentage of sprayers that have a given nozzle spacing. Some equipment accommodates multiple nozzle spacings. However, some equipment has fixed placement of nozzles and could be expensive to retrofit. If a grower has fixed nozzle spacing, the grower will have to purchase new nozzles to accommodate the fixed-spacing, invest in a sprayer that is adjustable, or pay to retrofit their existing boom. If an applicator applied at heights lower than the specification of the manufacture, the spray pattern may not overlap adequately and narrow strips of the field will be untreated, and consequently, may become infested with weeds.  

Impacts of Interaction of Individual Components of Spray Drift Mitigation

Impacts of multiple mitigations could be compounded and further reduce the time in which applicators could apply herbicides. For instance, applicators may deal with wind restrictions by spraying early in the morning/late evenings when winds are calmer; however, temperature inversions are more likely to occur several hours before sunset and can persist until 1-2 hours after sunrise.  As the window of application gets smaller, growers will be forced to switch to products without these restriction on short notice. Therefore, the alternative may be based on availability and not performance, which could be costly and reduce weed control. 

Additionally, growers may have situations where a tank is loaded and ready to spray, but they are not able to spray due to prolonged weather conditions that prevent application due to mandatory multi-layered restrictions. In rare situations, there could be scenarios where applicators cannot spray what is mixed in the tank for a long period of time and would need to dispose of a large quantity of mixed herbicides in order to switch to an alternative mixture. There may be additional concerns (e.g., tank clean-out when products settle out) when a loaded tank sits hours, and possibly days. 

 Environmental Hazard Statements

Non-target Organism Advisory

The agency is requiring the addition of a non-target organism advisory statement. The protection of non-target organisms and their habitats is a priority for the agency. Although risk to bees from the use of pyroxsulam is uncertain, it is possible that bees and other pollinators may be exposed to pyroxsulam from residues in pollen or nectar through spray drift. This may negatively impact forage and habitat of pollinators and other non-target organisms. It is the agency's goal to reduce spray drift whenever possible and to educate growers on the potential for indirect effects on the forage and habitat of pollinators and other non-target organisms. Therefore, the EPA is requiring non-target organism advisory language to be placed on pyroxsulam labels to address this potential concern. See Appendix B for the required advisory statement.

Groundwater and Surface Water Advisory Statements

The agency is also requiring surface water and ground water advisory statements for pyroxsulam because the environmental fate characteristics indicate that products containing pyroxsulam might be transported to surface water and groundwater. This language is consistent with current labeling practices as noted in the agency's FIFRA Label Review Manual. See Appendix B for the required advisory statements.

 Herbicide Resistance Management 

On August 24, 2017, the EPA finalized a Pesticide Registration Notice (PRN) on herbicide resistance management. Consistent with the Notice, the EPA is requiring the implementation of herbicide resistance measures for existing chemicals during registration review, and for new chemicals and new uses at the time of registration. In registration review, herbicide resistance elements will be included in every herbicide PID.

The development and spread of herbicide resistant weeds in agriculture is a widespread problem that has the potential to fundamentally change production practices in U.S. agriculture. While herbicide resistant weeds have been known since the 1950s, the number of species and their geographical extent, has been increasing rapidly. Currently there are over 250 weed species worldwide with confirmed herbicide resistance. In the United States, there are over 155 weed species with confirmed resistance to one or more herbicides.

Management of herbicide resistant weeds, both in mitigating established herbicide resistant weeds and in slowing or preventing the development of new herbicide resistant weeds, is a complex problem without a simple solution. Coordinated efforts of growers, agricultural extension, academic researcher, scientific societies, pesticide registrants, and state and federal agencies are required to address this problem.

The EPA is requiring measures for the pesticide registrants to provide growers and users with detailed information and recommendations to slow the development and spread of herbicide resistant weeds. This is part of a more holistic, proactive approach recommended by crop consultants, commodity organizations, professional/scientific societies, researchers, and the registrants themselves. 

    B. Tolerance Actions

No changes to the tolerance levels, crop listings, or the tolerance expression are required at this time.  Refer to Section III.A.2 for details.

    C. Interim Registration Review Decision 

In accordance with 40 CFR §§ 155.56 and 155.58, the agency is issuing this ID. Except for the Endocrine Disruptor Screening Program (EDSP), the Endangered Species Act (ESA), and pollinator components of this case, the agency has made the following interim decision: (1) no additional data are required at this time (the agency intends to issue a separate DCI for the pollinator data); and (2) changes to the affected registrations and their labeling are needed at this time, as described in Section IV.A and Appendices A and B.

In this ID, the agency is making no human health or environmental safety findings associated with the EDSP screening of pyroxsulam, nor is it making a complete endangered species finding or a complete assessment of effects to pollinators. Although the agency is not making an endangered species finding at this time, the required mitigation described in this document is expected to reduce the extent of environmental exposure and may reduce risk to federally listed species whose range and/or critical habitat co-occur with the use of pyroxsulam. The agency's final registration review decision for pyroxsulam will be dependent upon the result of the agency's ESA assessment and any needed ESA Section § 7 consultation with the Services and an EDSP FFDCA § 408(p) determination.

    D. Data Requirements

The agency does not anticipate any further human health data needs for the registration review of pyroxsulam.

No additional pollinator data are anticipated to be needed to be called‐in for this registration review at this time. The EPA will consider requiring submission of pollinator data as a separate action. 

 NEXT STEPS AND TIMELINE

 Interim Registration Review Decision

A Federal Register Notice will announce the availability of this ID for pyroxsulam. A final decision on the pyroxsulam registration review case will occur after: (1) an EDSP FFDCA § 408(p) determination, and (2) an endangered species determination under the ESA and any needed ESA Section § 7 consultation with the Services.

 Implementation of Mitigation Measures 

Once the Interim Registration Review Decision is issued, the pyroxsulam registrants must submit amended labels that include the label changes described in Appendices A and B. The revised labels and requests for amendment of registrations must be submitted to the agency for review within 60 days following issuance of the Interim Registration Review Decision in the docket.

Registrants must submit a cover letter, a completed Application for Registration (EPA form 8570-1) and electronic copies of the amended product labels. Two copies for each label must be submitted, a clean copy and an annotated copy with changes. In order for the application to be processed, registrants must include the following statement on the Application for Registration (EPA form 8570-1): 

"I certify that this amendment satisfies the requirements of the pyroxsulam Interim Registration Review Decision and EPA regulations at 40 CFR Section 152.44, and no other changes have been made to the labeling of this product. I understand that it is a violation of 18 U.S.C. Section 1001 to willfully make any false statement to EPA. I further understand that if this amendment is found not to satisfy the requirements of the pyroxsulam Interim Registration Review Decision and 40 CFR Section 152.44, this product may be in violation of FIFRA and may be subject to regulatory and/or enforcement action and penalties under FIFRA." 

Within the required timeframe, registrants must submit the required documents to the Re-evaluation section of the EPA's Pesticide Submission Portal (PSP), which can be accessed through the EPA's Central Data Exchange (CDX) using the following link: https://cdx.epa.gov/. Registrants may instead send paper copies of their amended product labels, with an application for a fast-track, agency initiated non-PRIA label amendment to Srijana Shrestha at one of the following addresses, as long as the labels and application are submitted within the required timeframe. 

VIA US Mail 
USEPA Office of Pesticide Programs 
Pesticide Re-evaluation Division 
Mail Code 7508P 
1200 Pennsylvania Ave NW 
Washington, DC 20460-0001 

VIA Courier 
Pesticide Re-evaluation Division 
c/o Front End Processing 
Room S-4910, One Potomac Yard 
2777 South Crystal Drive 
Arlington, VA 22202-4501  

 
  Appendix A:  Summary of Required Actions for Pyroxsulam

Registration Review Case#: 7275
PC Code: 108702
Chemical Type: Herbicide
Chemical Family:   Triazolopyrimidine sulfonamide
Mode of Action:  WSSA Group 2 (ALS inhibitors)
                                       
                            Affected Population(s)
                                       
                              Source of Exposure
                                       
                               Route of Exposure
                                       
                             Duration of Exposure
                                       
                         Potential Risk(s) of Concern
                               Required Actions
    Non- target Terrestrial and Semi-aquatic Plants
    Spray Drift
    Runoff

    Foliar and root absorption
    Acute
                                         
    Decreased biomass, effects on plant height and growth rate 
    Mandatory spray drift management
    Advisory spray drift reduction measures
    Non-target organism statement
    Surface water advisory measures
    Groundwater advisory measures
   
                                         

                                                                               

   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

 Appendix B: Required Labeling Changes for Pyroxsulam Products

                                  Description
                Required Label Language for Pyroxsulam Products
                              Placement on Label
                               End Use Products
Herbicide Resistance Management: Herbicide Mechanism of Action
Note to registrant:

::	Include the name of the ACTIVE INGREDIENT in the first column
::	Include the word "GROUP" in the second column
::	Include the MECHANISM OF ACTION CODE in the third column
::	Include the type of pesticide (i.e., HERBICIDE) in the fourth column.

--------------------------------------------------------------------------------
PYROXSULAM
--------------------------------------------------------------------------------
GROUP
--------------------------------------------------------------------------------
2
--------------------------------------------------------------------------------
HERBICIDE 

Front Panel, upper right quadrant.
Updated Gloves Statement
Update the gloves statements to be consistent with Chapter 10 of the Label Review Manual. In particular, remove reference to specific categories in EPA's chemical-resistance category selection chart and list the appropriate chemical-resistant glove types to use. 

In the Personal Protective Equipment (PPE) within the Precautionary Statements and Agricultural Use Requirements, if applicable
Groundwater Advisory
"GROUND WATER ADVISORY: This chemical has properties and characteristics associated with chemicals detected in groundwater. This chemical may leach into groundwater if used in areas where soils are permeable, particularly where the water table is shallow." 
Environmental Hazards
Surface water Advisory
"SURFACE WATER ADVISORY: This product may impact surface water quality due to runoff of rain water. This is especially true for poorly draining soils and soils with shallow ground water.

This product is classified as having high potential for reaching surface water via runoff for several weeks after application.

A level, well-maintained vegetative buffer strip between areas to which this product is applied and surface water features such as ponds, streams, and springs will reduce the potential loading of pyroxsulam from runoff water and sediment. Runoff of this product will be reduced by avoiding applications when rainfall or irrigation is expected to occur within 48 hours."
Environmental Hazards
Non-target Organism Advisory
"NON-TARGET ORGANISM ADVISORY: This product is toxic to plants and may adversely impact the forage and habitat of non-target organisms, including pollinators, in areas adjacent to the treated site. Protect the forage and habitat of non-target organisms by following label directions intended to minimize spray drift."

Environmental Hazards
Herbicide Resistance Management: Weed Resistance Management
Include resistance management label language for herbicides from PRN 2017-1 and 
PRN 2017-2 (https://www.epa.gov/pesticide-registration/pesticide-registration-notices-year)
Directions for Use, prior to directions for specific crops under the heading "WEED RESISTANCE MANAGEMENT"
Spray Drift Management Application Restrictions for products delivered via liquid spray applications and that allow aerial application
"MANDATORY SPRAY DRIFT MANAGEMENT
Aerial Applications:
 Do not release spray at a height greater than 10 ft above the ground or vegetative canopy, unless a greater application height is necessary for pilot safety.
 Applicators are required to use a medium or coarser droplet size (ASABE S572.3).
 If the windspeed is 10 miles per hour or less, applicators must use (1/2) swath displacement upwind at the downwind edge of the field.  When the windspeed is between 11-15 miles per hour, applicators must use (3/4) swath displacement upwind at the downwind edge of the field.
 Do not apply when wind speeds exceed 15 mph at the application site.  If the windspeed is greater than 10 mph, the boom length must be 65% or less of the wingspan for fixed wing aircraft and 75% or less of the rotor diameter for helicopters. Otherwise, the boom length must be 75% or less of the wingspan for fixed-wing aircraft and 90% or less of the rotor diameter for helicopters.
 Do not apply during temperature inversions."
      
Directions for Use, in a box titled "Mandatory Spray Drift Management" under the heading "Aerial Applications," and before use rates and/or application instructions
Spray Drift Management Application Restrictions for products that are delivered via liquid spray applications and that allow ground boom applications
"MANDATORY SPRAY DRIFT MANAGEMENT
Ground Boom Applications:
    User must only apply with the release height recommended by the manufacturer, but no more than 3 feet above the ground or crop canopy.
    Applicators are required to use a medium or coarser droplet size (ASABE S572.3).
    Do not apply when wind speeds exceed 15 miles per hour at the application site.
    Do not apply during temperature inversions."
Directions for Use, in a box titled "Mandatory Spray Drift Management" under the heading "Ground Boom Applications"
Advisory Spray Drift Management Language for all products delivered via liquid spray application
"SPRAY DRIFT ADVISORIES
THE APPLICATOR IS RESPONSIBLE FOR AVOIDING OFF-SITE SPRAY DRIFT.
BE AWARE OF NEARBY NON-TARGET SITES AND ENVIRONMENTAL CONDITIONS.
IMPORTANCE OF DROPLET SIZE
An effective way to reduce spray drift is to apply large droplets. Use the largest droplets that provide target pest control. While applying larger droplets will reduce spray drift, the potential for drift will be greater if applications are made improperly or under unfavorable environmental conditions.
Controlling Droplet Size  -  Ground Boom (note to registrants: remove if ground boom is prohibited on product labels)
:: Volume - Increasing the spray volume so that larger droplets are produced will reduce spray drift. Use the highest practical spray volume for the application.  If a greater spray volume is needed, consider using a nozzle with a higher flow rate.
:: Pressure - Use the lowest spray pressure recommended for the nozzle to produce the target spray volume and droplet size.
:: Spray Nozzle - Use a spray nozzle that is designed for the intended application. Consider using nozzles designed to reduce drift.
Controlling Droplet Size  -  Aircraft (note to registrants: remove if aerial application is prohibited on product labels)
:: Adjust Nozzles - Follow nozzle manufacturers' recommendations for setting up nozzles. Generally, to reduce fine droplets, nozzles should be oriented parallel with the airflow in flight.
BOOM HEIGHT  -  Ground Boom (note to registrants: remove if ground boom is prohibited on product labels)
For ground equipment, the boom should remain level with the crop and have minimal bounce.
RELEASE HEIGHT - Aircraft (note to registrants: remove if aerial application is prohibited on product labels)
Higher release heights increase the potential for spray drift.
SHIELDED SPRAYERS
Shielding the boom or individual nozzles can reduce spray drift. Consider using shielded sprayers. Verify that the shields are not interfering with the uniform deposition of the spray on the target area.
TEMPERATURE AND HUMIDITY
When making applications in hot and dry conditions, use larger droplets to reduce effects of evaporation.
TEMPERATURE INVERSIONS
Drift potential is high during a temperature inversion. Temperature inversions are characterized by increasing temperature with altitude and are common on nights with limited cloud cover and light to no wind. The presence of an inversion can be indicated by ground fog or by the movement of smoke from a ground source or an aircraft smoke generator. Smoke that layers and moves laterally in a concentrated cloud (under low wind conditions) indicates an inversion, while smoke that moves upward and rapidly dissipates indicates good vertical air mixing. Avoid applications during temperature inversions.
WIND
Drift potential generally increases with wind speed. AVOID APPLICATIONS DURING GUSTY WIND CONDITIONS.
Applicators need to be familiar with local wind patterns and terrain that could affect spray drift."

Directions for Use, just below the Mandatory Spray Drift box, under the heading "Spray Drift Advisories"
Additional Required Labeling Action--Applies to all products delivered via liquid spray applications
    Remove information about volumetric mean diameter from all labels where such information currently appears.
Directions for Use