Docket Number EPA-HQ-OPP-2010-0815 www.regulations.gov



## Carfentrazone-ethyl Final Work Plan Registration Review

August 2011

## Carfentrazone-ethyl Final Work Plan Registration Review

Case # 

## 7422

Approved By:



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Richard P. Keigwin, Jr.

Director

Pesticide Re-evaluation Division

Date

23 Introduction

This is the Environmental Protection Agency’s (EPA’s) Final Work Plan for the registration review of carfentrazone-ethyl. This work plan in cludes the expected regist ration review timeline. The work plan also addresses publ ic comments received concerning the Preliminary Work Plan

in the Summary Document , which was posted in the carfentr azone-ethyl registration review docket (EPA-HQ-OPP-2010-0815), and any other co mments concerning the initial docket postings. The Summary Document provided information on wh at EPA knows about the pesticide and what additional risk analyses and data or information the Agency believes are needed to make a registration review decision.

The Agency is implementing the registration revi ew program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered pesticide every 15 years to determine whether it continues to meet th e FIFRA standard for registration. Changes in science, public policy, an d pesticide use practices will occur over time. The registration review program is intended to ma ke sure that, as the ability to assess risk evolves and as policies and practi ces change, all registered pes ticides continue to meet the statutory standard. The public pha se of registration review begins when the initial docket is opened for each case. Information on this program is provided at: http://www.epa.gov/oppsrr d1/registration_review/

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Carfentrazone-ethyl is a post-emerge nt herbicide registered for use to control broadleaf weeds. It is registered for use on a variety of agricultural crops, turf (including golf courses and residential lawns), aquatic areas (including water bodies and wetlands), and i ndustrial and utility sites. Carfentrazone-ethyl is part of the class of herbic ides referred to as Ligh t Dependent Peroxidizing Herbicides (LDPH), which have enhanced toxicity in the presence of solar ultraviolet light. Carfentrazone-ethyl was first registered in th e United States in 1998, a nd therefore it was not subject to the FIFRA reregistration program.

Comments Received on Preliminary Work Plan

Comments were received during the 60-day pub lic comment period on the planned ecological

assessment discussed in the Preliminary Work Plan . However, these comments do not alter the Agency’s Preliminary Work Plan for the registration review of carfentrazone-ethyl. For further discussion on these comments, please see the Summary of Comments and Agency Responses

section of this document. In the Preliminary Work Plan , EPA also solicited comments on three specific topics: environmental justice, water body impairment, and trade irritants. No information was received during the comment period concerning environmental ju stice, trade irritants, or water body impairment.4 Anticipated Risk Assessment and Data Needs

The Agency anticipates requiring data consid ered necessary to conduct a comprehensive ecological risk assessment, including an endangere d species risk assessment, and to update the human health risk assessment for all uses of carfentrazone-ethyl. Belo w is a summary of the issues relevant to the regist ration review of carfentrazone-e thyl and the data the Agency anticipates requiring.

Ecological Risk:

• Since carfentrazone-ethyl products are register ed for direct applica tions to water, the Agency anticipates requiring additional data to assess potential risk to aquatic organisms. The Agency anticipates requiring data on th e degradate carfentrazone acid, which is expected to be dominant in water afte r application of car fentrazone-ethyl.

• Given that carfentrazone-ethyl is an herbic ide, and incident reports confirm adverse effects to non-target plants, the Agency anticipates requiring additional data to assess potential risk to terrestrial plants. Toxicity data usi ng a typical end-use product is anticipated to be required to evaluate risk to plants.

• Toxicity data are not available for passerine bird species that ma y, in some cases, be more sensitive than the waterfowl and upland game birds that were tested in previous carfentrazone-ethyl studies. The Agency anticipates requiring passerine data.

• LDPH registrants are in the process of conduc ting a modified freshwater fish early life stage study to quantitatively determine the increase in toxicity of this class of herbicides in the presence of direct sunlight. The Agency expects to receive these data in the winter of 2011 in response to the Data Call-in (DCI) for this study. These data will be used in the registration review ecological risk assessment for carfentrazone-ethyl.

• The Agency has not conducted an ecological risk assessment that supports a complete endangered species determination for carfe ntrazone-ethyl. The ecological risk assessment planned during registration revi ew will allow the Agency to determine whether carfentrazone-ethyl’s use has “no effect” or “may affect” federally listed threatened or endangered species (listed specie s) or their designated critical habitats. When an assessment concludes that a pesticid e’s use “may affect” a listed species or its designated critical habitat, the Agency w ill consult with the U.S. Fish and Wildlife Service (FWS) and/or National Marine Fisher ies Service (NMFS) (the Services), as appropriate.

• The Agency anticipates requiring the followi ng data in order to conduct a complete ecological risk assessment, including an endangered species assessment, for carfentrazone-ethyl:5 Environmental fate

o Guideline No. 835.2240 – Photodegradation in water (carfentrazone acid)

o Guideline No. 835.4400 – Anaerobic aquatic metabolism

o Guideline No. 835.6100 – Terrestrial field dissipation (only an independent laboratory validation (ILV) of the subm itted analytical method would likely be required to satisfy this guideline)

o Guideline No. 835.6200 – Aquatic) field dissipat ion (only frozen storage stability data would likely be required to satisfy this guideline)

Ecological toxicity

o Guideline No. 850.1025 – Invertebrates acute toxicity – mollusk (saltwater) (carfentrazone acid)

o Guideline No. 850.1075 – Fish acute toxicity (saltwater) (carfentrazone acid)

o Guideline No. 850.1300 – Aquatic invertebrate life-cycle (freshwater) (carfentrazone acid)

o Guideline No. 850.1350 – Aquatic invertebrate life-cycle (saltwat er) (carfentrazone acid)

o Guideline No. 850.1400 – Fish early life stag e (saltwater) (carfentrazone acid)

o Guideline No. 850.1500 – Fish life-cycle (f reshwater) (carfentrazone acid)

o Guideline No. 850.2100 – Avian acute oral toxicity (passerine species)

o Guideline No. 850.4100 - Seeding Emergence (Tier II)

o Guideline No. 850.4150 - Vegetative Vigor (Tier II)

• Please refer to the March 8, 2011 “ Registration Review: Preliminary Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for Carfentrazone-ethyl ,” for a more detailed discussion of the anticipated ecological risk assessment and data needs.

Human Health Risk:

• The Agency anticipates conducting a drinking water assessment in registration review. Results of the updated drinking water assessment may necessitate a revised dietary

exposure assessment.

• The Agency anticipates conducting new o ccupational exposure assessments in registration review. Several occupational ha ndler scenarios need to be assessed, which have not been assessed previously, or need to be reassessed base d on higher application

rates or area treated.

• A revised residential exposure assessment may need to be performed to include residential handler scenarios and updated re sidential post-application scenarios (higher turf/home lawn application rate). This may necessitate a new aggregate exposure

assessment.6 • If new policies or procedures are put into place, the Agency may revisit the need for a quantitative post-application inhalation exposure assessment for carfentrazone-ethyl.

• The analytical tolera nce enforcement method for lives tock, fish, and shellfish was considered acceptable pending validation from EPA’s Analytical Chemistry Laboratory. However, the validation procedure has cha nged, and now laboratory validation is not required. As part of registra tion review, the Agency may eval uate the suitability of the existing analytical tolerance enforcement method for livestock, fish, and shellfish according to new procedures. If the method is found to be unsuitable for tolerance enforcement, then the techni cal registrant would need to propose and validate a new

method.

• As part of registration review, the Agency anticipates making the following tolerance changes:

o The banana tolerance may be lowered to 0.10 ppm.

o The following currently-established toleran ces may be deleted: cotton hulls, cotton meal, cotton oil, barley flour, barley bran, millet flour, oat flour, rye flour, rye bran, wheat bran, wheat flour, wheat middlings, wheat shorts, wheat germ, and caneberry subgroup 13A.

o The cereal grain forage, hay, stover, and stra w tolerances may be altered as there are conflicting commodity definitions and/or tolerance levels.

o The tolerance expression may be updated as fo llows to conform to current standards:

Tolerances are established for residues of carfentrazone-ethyl, including its metabolites and degradates, in or on the comm odities listed below. Compliance with the following tolerance levels is to be determined by measuring carfentrazone-ethyl (ethyl alpha-2-dichloro-5-[4-(difluor omethyl)-4,5-dihydro-3- methyl-5-oxo-1H-1,2,4-triazol-1-yl]-4-fluorobenzenepropanoate) and its metabolite carfentrazonechloropropionic acid (alpha, 2-dichloro-5-[4-difluor omethyl)-4,5-dihydro-3-methyl5-oxo-1H-1,2,4-triazol-1-yl]-4-fl uorobenzenepropanoic acid).

• The Agency anticipates requiring the followi ng data in order to conduct a complete

human health risk assessme nt for carfentrazone-ethyl:

• A 28-day inhalation toxicity study was previo usly waived for carfentrazone-ethyl. However, the Agency is re-evaluating its inha lation waiver criteria, so this study may be required for registration review.

o Guideline No. 870.3465 – 90 1 -day inhalation - rat

o Guideline No. 870.7800 – Immunotoxicity

1 A 28-day study may be sufficient to satisfy guideline requirement.7 • In addition, the Agency anticipates requiri ng the following residue chemistry data to complete the residue chemistry da tabase for carfentrazone-ethyl.

o Guideline No. 860.1500 Crop Field Trials – soybeans In lieu of conducting this study the registrant may revise label language to include a restriction prohibiting the feeding of soybean forage and hay to livestock.

o Guideline No. 860.1500 Crop Field Trials - cranberry In lieu of conducting this study the registrant may remove instructions for application to cranberry from all labels.

o Guideline No. 860.1500 Crop Field Trials – dry peas, vegetable legume (Group 6), and vegetable foliage of legume (group 7) In lieu of conducting these studies the regist rant may revise label language to restrict harvest-aid application to only the followi ng crops: cereal grains, soybean, cotton, peanut, sugarcane, and potato.

o Guideline No. 860.1900 Field Rotational Crops In lieu of conducting this study the registrant may revise label langua ge that indicate the following rotational crop restri ctions: seasonal ap plication rate of <0.031 lb ai/acre - rotate to a registered crop at anytime and to all other crops 12 mont hs after application; seasonal application rate of >0.031 lb ai/acre - rotate to only a registered crop.

Provided these changes are made, the residue chemistry database will be adequate to support carfentrazone-ethyl registrations.

• Please refer to the January 19, 2011 “ Carfentrazone-ethyl. Human Health Assessment Scoping Document in Support of Registration Review, ” available in the docket, for a

detailed discussion of the an ticipated human health risk assessment and data needs.

Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews num erous studies to asse ss potential adverse outcomes from exposure to chemicals. Collectiv ely, these studies includ e acute, subchronic and chronic toxicity, including asse ssments of carcinogenicity, ne urotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influe nce, including effects on endocri ne target organ histopathology, organ weights, estrus cyclicity, sexual maturatio n, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess gr owth, developmental and reprod uctive effects in different taxonomic groups. As part of its most recent registration decision, EPA reviewed these data and selected the most sensitive endpoi nts for relevant risk assessment scenarios from the existing8 hazard database. However, as required by FFDCA section 408(p), carfentrazone-ethyl is subject to the endocrine screening pa rt of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whet her certain substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or ot her such endocrine effect s as the Administrator may designate.” The EDSP employs a two-tiered approach to making th e statutorily required

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact with the estrog en, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go th rough Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stag e of the EDSP where EPA will determine which, if any, of th e Tier 2 tests are necessary base d on the available data. Tier 2 testing is designed to identify a ny adverse endocrine-related eff ects caused by the substance, and establish a dose-response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, which contains 58 pest icide active ingredients and 9 inert ingredients. Carfentrazoneethyl is not among the group of 58 pesticide active ingredients on th e initial list to be screened under the EDSP. Accordingly, as part of regi stration review, EPA will issue future EDSP orders/data call-ins, requiring th e submission of EDSP screening a ssays for carfentrazone-ethyl.

For further information on the status of the ED SP, the policies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening batt ery, please visit our

website: http://www.epa.gov/endo/

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Timeline

The Agency has created the following estimated timeline for the completion of the registration review for carfentrazone-ethyl. One year has be en added to the projected timeline included the Preliminary Work Plan. In the Preliminary Work Plan, the time frame between issuing the DCI and data submission was projected to be two years. However, one of the anticipated data requirements, field accumulation study in rotatio nal crops (Guideline No. 860.1900), is actually a three year study. However, in lieu of conductin g this study the registrant may revise label language. If the registrant choos es that option, the time frame between issuing the DCI and data submission will be reduced to two years from the current three years.

Registration Review for Carfentrazone-ethyl – Projected Registra tion Review Timeline

Activities Estimated Date Opening the docket Open Docket and Public Co mment Period 2011 – March

Close Public Comment 2011 – May Case Development

Final Work Plan 2011 – August9 Issue DCI 2012 – Apr. - June

Data Submission 2015 – Apr. - June Open Public Comment Period for Prelimin ary Risk Assessments 2016 – Oct. - Dec.

Close Public Comment Period 2017 – Jan. - March Registration Review Decision Open Public Comment Period for Proposed Registration Review

Decision 2017 – Apr. - June

Close Public Comment Period 2017 – July – Sept. Registration Review Decision and Begin Post-Decision Follow-up 2018 Total (years) 7

Summary of Comments and Agency Responses The carfentrazone-ethyl regi stration review docket was ope n for a 60-day comment period beginning in March 2011. The comm ents received did not result in a change to the Agency’s Preliminary Work Plan for carfentrazone-ethyl. However, it did result in a change to the data requirements.

For the sediment tests : The partitioning of carfentrazone-ethyl between soil and water is uncertain because acceptable batch equilibrium data have not been submitted. However, aquatic laboratory (MRID 44419016) and field studies (MRIDs 44654701, 46253901) indicate that less than 10% of applied carfentrazone-ethyl will partiti on to sediment. Due to the apparent lack of partitioning of carfentrazone-ethyl to sediment , the requested whole sediment data (OCSPP guidelines 850.1735 and 850.1740) will not be required for the Data Call-in for carfentrazoneethyl.

FMC Corporation Agricultural Products Group (F MC) commented that it was a member of the FIFRA Endangered Species Task Force and cited information from studies already submitted along with a rationale explaining ho w these data might negate the need for some of the requested studies from the Registration Review Problem Formulation Da ta Call-In. FMC commented on the following list of data needs for environmental fate and ecological toxicity:

(1) cited an ILV to support the 1994 so il dissipation study (RAN-0270, MRID 44165039 and RAN-0270M, MRID 44165040), also noting th e 1995 soil dissipation study (MRID 44419018) and subsequent ILV (MRID 44165043;

Agency Response : MRID 44419018 was not the analytical method used in the terrestrial field dissipation (TFD) study submitted under MRID 44165039. The Agency is requesting an independent laboratory va lidation (ILV) of MR ID 44165040, which is the analytical method used in MRID 44165039. Th is method included a methylene chloride partition, did not include solid phase extraction, and di d not analyze for 3-OH-F8426-

BAc. If an ILV is not submitted to support MRID 44165040 or if a submitted ILV indicates that the analytical method in MR ID 44165040 is not quantitative, then the study classification for the TFD study it supports may be downgraded and additional terrestrial10 field dissipation data may be requested.

(2) that the required storage stability data for water, soil and sediment in two aquatic filed dissipation studies have al ready been reported in th ree separate reports;

Agency Response: Frozen storage stability data are needed to support the aquatic field dissipation study, MRID 44654701, in which thes e data were not provided (MRIDs

44419019 and 46253901 have additional deficiencies that are not upgradeable). The following are the available storage stabil ity data on carfentrazone-ethyl and its transformation products:

• MRID 44165049: This is a frozen storage st ability study of transformation products of carfentrazone-ethyl stored for 15 months in soil. These data may not be relevant to the storage stability of these compounds in the sediment sampled in aquatic field dissipation studies. Carfentr azone-ethyl was not studied.

• MRID 44419019: This is an unacceptable aquati c field dissipation study. A storage stability study was not conducte d. However, field spikes we re prepared in water and stored frozen with water samples for 105-110 days. The field spikes indicated that carfentrazone-ethyl was not stable in water in storage. Recoveries were 8±2% for Site 1 and 21±2% for Site 2. Field spikes we re not prepared in soil or sediment. The study authors indicated that carfentrazone-et hyl has not been included in frozen soil stability studies because it is known to de grade rapidly in soil, even in frozen conditions (p. 13).

• MRID 44654701: This is an upgradeable aqua tic field dissipation study with no storage stability study. However, sediment that was spiked and stored frozen

indicated that carfentrazone -ethyl degraded 67% over 9 months. It was not clear whether the sediment was spiked in the fi eld and handled and processed similar to study samples or spiked in the laboratory. Fi eld spikes were not prepared in soil or water. Study samples were stored frozen for 5 months (soil), 6 months (sediment), and 107 days (water).

• MRID 46253901: This is a supplemental aqua tic field dissipation study with no storage stability study. Field spikes were pr epared in water and sediment. However, they were only stored frozen for 3-6 days ; whereas, study samples were stored for up to 1 month. Additionally, r ecoveries in water after 3- 6 days were poor. The study authors followed up with laboratory spikes and additional field spikes from another site. However, the following spikes were irrelevant because the original field spike

results were not shown to be invalid.

(3) some photodegradation studies in water (carfentrazone acid) a nd ecological t oxicity are not needed because of rapid degrada tion and nearly complete conver sion of carfentrazone-ethyl to11 carfentrazone chloropropionic acid in aqueous environments. Thus, FMC requested that the following studies be waived: aqueous photodegr adation using carfentrazone-ethyl, aquatic invertebrate life cycle studies for both fresh and saltwater, and fish early life-stage and fish full life cycle studies.

Agency Response:

• Photodegradation Study : Carfentrazone acid was not detected in the submitted, acceptable aqueous photolysis study conducte d with carfentrazone-ethyl (MRID 44934201). Because carfentrazone-ethyl underg oes nearly complete conversion to carfentrazone acid in aqueous environments, the environmental fate of carfentrazone

acid in water needs to be understood. Ther efore, the Agency is requesting aqueous photolysis data on carfentrazone acid.

• Aquatic Invertebrate and Fish Chronic Studies: Since carfentrazone-ethyl is applied directly to water, chronic data are required for aquatic invertebrates and fish. The rationale for asking for the acid, rather than the parent, is the rapid breakdown. For aquatic invertebrates, the daphnid study (MRID 44419006) was classified invalid and may not be used for risk assessment. The Agency needs acceptable chronic toxicity data using aquatic invertebrates to assess risk of carfentrazone acid to these

taxa.

For fish, MRID 44424201 is an acceptable rain bow trout early life-stage (ELS) flowthrough study for carfentrazone-ethyl, howev er, this study does not satisfactorily address the chronic toxicity of carfentrazone-ethyl acid.

Two of the submitted fish ELS studi es (MRIDs 44963201 and 46037001) are rainbow light-dependent peroxidizing herbicide (L DPH) studies conducted under enhanced lighting conditions to estimate the enhan ced toxicity of carfentrazone-ethyl under strong light. However, these studies are ba sed on parent light-e nhanced toxicity and

the concentration of carfentra zone-ethyl acid was not determ ined. LDPH toxicity will be evaluated in the risk assessment, but ch ronic toxicity data on the major degradate (carfentrazone-ethyl acid) is needed, as well.

FMC commented that while EPA is re-evaluating its inhalation waiver criteria for the 28-day inhalation toxicity study, which was previously waived for carfentrazone-ethyl; the criteria basis for the inhalation waiver previously granted by the Agency has not changed.

FMC also commented that while EPA’s Fact Sh eet indicated “there are no recent or pending actions for carfentrazone-ethyl,” FMC notes th at there are pending labe l amendment and PRIA actions to add new crop uses.

Agency Response: When conducting the Preliminary Risk Assessment for carfentrazone-ethyl, any pending new uses will be taken into account, if they are approved.12 Additional clarification to the Agency’s above responses to FMC comments are provided in the response to public comments document located in docket EPA-HQ-OPP-2010-0815.

The Physicians Committee for Responsible Medicine commented on potential alternative methods for conducting some of the anticipated toxi city studies.

Agency Response : The Agency responded that it is currently evaluating the results from studies utilizing the alternative guideline for consistency with the data requirements described in 40 CFR Part 158 and 40 CFR Part 161. Additionally, until validation has occurred for this guideline, as it relates to certain species studie s, it is doubtful the Agency would have confidence in studies done under this alternative guideline. However, the Agency recognizes that specific situa tions might warrant additional examination.

The FIFRA Endangered Species Task Force (FESTF ) commented that it has submitted data to the Agency that fulfill the requirements of Pes ticide Registration Notice 2000-2 and is the best available data necessary for the proximity analysis of Carfentrazone-ethyl use and listed species

locations. FMC is a member of FESTF and is entitled to rely on FEST F data. For all other nonmember registrants, FESTF is making every effo rt to inform them of role of FESTF data.

Agency Response: The Agency thanks FESTF for its comment and will consider this information as it conducts the registration review and makes its registration review

decisions.

The public comments and the Agency’s response, “ Response to Public Comments on Registration Review Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for Carfentrazone-ethyl

, ” dated August 16, 2011, are available in docket EPA-HQ-OPP-2010-0815.

Next Steps

The Agency plans to issue a Data Call-in (DC I) for carfentrazone-ethyl in 2012. The information received in response to this DCI will be used to conduct the planned human health, ecological risk, and endangered species asse ssments for carfentrazone-ethyl.

Summary of Data Needs for the Registra tion Review of Carfentrazone-ethyl

Guideline

Number Data Requirement Test Substance Estimated

Timeframe (months)

835.2240 Aqueous Photolysis Carfentrazone acid 12

835.4400 Anaerobic Aquatic Metabolism Carfentrazone-ethyl 24 835.6100 (ILV) Independent Laboratory Validation Parent plus analyzed degradates 24 835.6200 (SS) Frozen Storage Stability 2413 850.1025 Oyster Acute Toxicity

Carfentrazone acid 12

850.1075 Fish Acute Toxicity 24

850.1300 Daphnid Chronic Toxicity 12

850.1350 Mysid Chronic Toxicity 12

850.1400 Fish Early Life Stage (ELS) Toxicity 12

850.1500 Fish Life-Cycle Toxicity 2 24

850.2100 Avian Acute Oral Toxicity Carfentrazone-ethyl 12

850.4100 Tier II Plant Toxicity – Seedling Emergence Typical End-Use

Product 12

850.4150 Tier II Plant Toxicity – Vegetative Vigor 12

860.1500 Crop Field Trials – Soybean 3 24

860.1500 Crop Field Trials – Cranberry 4 24

860.1500 Crop Field Trials – Dry Peas, Vegetable Legume (Group 6), and Vegetable Foliage of Legume (Group 7) 5 24

860.1900 Field Rotational Crops 6 36

870.3465 90-day inhalation 7 - Rat 24

870.7800 Immunotoxicity 12

2 Data requirement may be satisfied by submission of an ELS study. However, results from an ELS study may trigger a life-cycle study.

3 In lieu of conducting the study, the registrant may revise label language to include a restriction prohibiting the feeding of soybean forage and hay to livestock.

4 In lieu of conducting the study, the registrant may remove instructions for application to cranberry from all labels.

5 In lieu of conducting the study, the registrant may revise la bel language to restrict harvest-aid application to only the following crops: cereal grains, soybean, cotton, pean ut, sugarcane, and potato.

6 In lieu of conducting the study, the registrant may revise label language that indicate rotational crop restrictions for seasonal application rates of <0.031 lb ai/acre – rotate to a registered crop at anytim e and to all other crops 12 months after application; seasonal application rate of >0.031 lb ai/acre – rotate to only a registered crop.

7 A 28-day study may be sufficient to satisfy guideline re quirement. A waiver was d eemed acceptable for this guideline study in August 2002, however, the Agency is currently reevaluating the inhalation waiver criteria and based on this analysis, an inhalation study may be required in the future.