Registration Decision of the New Active Ingredient 

Bicyclopyrone 

An Herbicide for Use on Corn and Establishment of 

Tolerances for Corn (field, pop, and sweet) and Imported 

Sugarcane 
Summary 

This document announces that the U.S. Environmental Protection Agency (EPA) has completed 

its evaluation of the new herbicide bicyclopyrone and has concluded that it meets the regulatory 

standard under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Five products 

will be registered under Section 3(c)(7)(C) ofFIFRA: one technical product, two manufacturinguse products (Bicyclopyrone Wet Paste Manufacturing Use Product and Bicyclopyrone Wet 

Paste II Manufacturi ng Use Product), and two end-use products (SYN-A l 6003 Herbicide and 

AcuronTM Herbicide). The product AcuronTM will contain 0.65% bicyclopyrone, 2.60% 

mesotrione, 10.93% atrazine, and 23.40% S-metolachlor. The product SYN-A 16003 will 

contain 18.5% bicyclopyrone. The labels specify that bicyclopyrone is generally to be applied 

once annually as a pre-emergent application to corn; however, a split application for preemergent and early post-emergent is allowed, provided the maximum single and annual 

application rates arc not exceeded. Identical rates and use patterns apply to both end use 

products. 

ln accordance with 3(c)(7)(C) of FIFRA the agency has determined that registering 

bicyclopyrone is in the public interest. AcuronTM can control weeds with a single pre-emergent 

application that may not require additional post-emergent applications. Acuronn1 will be labeled 

for difficult to control weeds with a lower rate of atrazine, S-metolachlor, and mesotrione; 

resulting in decreases in the amount of atrazine that will be applied to corn as well as small er 

reductions in S-metolachlor and mesotrione. AcuronTM's penetration into the market will result 

in the reduction of other Syngenta atrazine products, resulting in a reduction of 3.6 million 

pounds of atrazine per year on acres that would have been treated with those products. The 

agency is requiring Syngenta to achieve this reduction no later than the 2020 growing season. 

Labels have language including surface and ground water advisories that stress the potential for 

runoff management after treatment and statements intended to preclude leaching to groundwater. 

Language is on the label that is intended to keep the pesticide on the intended treatment area and 

instructs users of applicator responsibilities and specific techniques to reduce the possibility of 

spray drift. Aerial application is prohibited and a 25-foot downwind buffer is required to avoid 

drift to non-target areas. End use labels also contain guidance and information which will slow 

the development of resistance to the target weeds. 

Backgr·ound 

On September 23, 20 13, EPA received an application to register products containing the new 

active ingredient, bicyclopyrone (CAS Number 3520 I 0-68-5), an herbicide for use on corn 

(field, pop, and sweet) from Syngenta Crop Protection. Syngenta also submitted applications for 

simultaneous revievv to the Pest Management Regulatory Agency (PM RA) of Canada and the 

Australian Pesticides and Veterinary Medicines Authority (APYMA). The EPA. PMRA, and 

APVMA combined scientific and regulatory expertise to conduct a joint review. Each country's 

team of scientists peer-reviewed the primary reviews of their counterparts. While continuing to 

consult and coordinate, human health and ecological risk assessments were developed by each 

country individually. 

2 
Bicyclopyrone is an herbicide for use on corn with the establishment of tolerances on corn and 

imported sugarcane. Bicylcopyrone is to be used on corn for the selective contact and residual 

control 

maximum 

of weeds in field corn, seed corn, silage corn, yellow popcorn, and sweet corn. The 

single and maximum annual application rates are 0.045 lb ai/acre. One pre-emergent 

application is allowed, but the labels do allow for split applications (one pre-emergent and one 

early post-emergent) as long as the maximum single and annual application rates arc not 

45 

exceeded. The minimum retreatment interval (RTI) is 14 days; the pre-harvest interval (PHI), is 

days. 

metolachlor 

AcuronTM contains 0.65% bicyclopyrone, 2.60% mesotrione, I 0.93% atrazine, and 23.40% SA 

giving the product three different modes of actions (MoA). The product SYN16003 contains 16.5% bicyclopyrone and only one MoA. The label for AcuronTM contains 

in formation on each of the three different modes of actions. The label for SYN-A 16003 contains 

in formation on the MoA for bicyclopryone. Bicyclopyrone and mesotrione are members of the 

Act

hydroxyphenylpyruvate dioxygenasc (HPPD) inhibitor class of herbicides (Herbicide Resistance 

ion Committee (HRAC) Group 27) and belong to the triketone subclass of chemistry. 

At

Bicyclopyrone and mesotrione inhibit the enzyme I-IPPD and block biosynthesis in plants. 

razine is a member of the triazine family of herbicides (HRAC Group 5). Atrazine works by 

inhibiting photosynthesis. S-Metolachlor is a member of the chloroacetamide family of 

herbicides (HRAC Group 15). S-Metolachlor is a seedling shoot growth inhibitor. 

The maximum single and maximum total annual rates for AcuronTM are 3 quarts per acre. When 

mesotrione

applied at this rate, AcuronTM will apply 0.045 \b ai/acre ofbicyclopyrone, 0.18\b ai/acre of 

, 0. 75 lb ai/acre of atrazine, and 1.605 lb ai/acrc of S-metolachlor per single 

application and total per year. The maximum total annual rates on corn, allowed by the agency, 

The 

for meso

maximum 

trione is 0.24 lb ai/acre, atrazine is 2.5 lb ai/acre, and S-metolachlor is 3.7 1 lb ai/acre. 

single and maximum total annual rates for AcuronTM are below the maximum use 

rates allowed by the agency for mesotrione, atrazine, and S-metolachlor. 

Evaluation 

In evaluating a pesticide registration application, the EPA assesses a wide variety of exposure 

information (i.e., where and how the pesticide is used) and environmental fate (i.e., how the 

chemical will move in the environment) and toxicity studi es (i.e., effects on humans and other 

non-target organisms) to detem1ine the likelihood of adverse effects (i.e., risk) from exposures 

associated with the proposed use of the product. Risk assessments are developed to evaluate the 

environmental fate of the compound as well as how it might affect a wide range of non-target 

organisms including humans, terrestrial and aquatic wildlife and plants. On the basis of these 

assessments, EPA evaluates and approves language for each pesticide label to ensure the 

directions for use and safety measures are appropriate to mitigate any potential risk. The 

pesticide's label helps to communicate essential limitations and mitigations that are necessary for 

public safety. It is a violation of federal law to use a pesticide in a way that conflicts with the 

label. 

3 
Assessment of Risk to Human Health 

EPA requires a wide range of studies in order to assess a pesticide. Both bicyclopyrone (active 

ingredient specific) and AcuronTM (mixture specific) fall in the lowest acute toxicity category of 

IV via the eye, oral, dermal, and inhalation routes. The labeling precautionary signal word is 

"CAUTION" for all products. Atrazine also shows low acute toxicity data. The acute toxicity 

effects are similar and do not indicate a synergistic effect for atrazine and bicyclopryone for 

mammals. The table below summarizes the toxicological endpoints used in the human health 

risk assessment: 

Summary of Tox icologica l Doses and Endpoints for Bicyclopyrone for Use in Human Health Risk 

Assessments. 

RfD, PAD, 

Ex posure/ POD Uncertainty/FQJ> LOC for Study and Toxicologica l Effects Scenario A Sa fety Factors Risk 

Assessment 

Acute Dietary 

(General No endpoint attributable to a single dose and appropriate for the U.S. general population was Population, 

including seen in the bicyclopyrone toxicological database; therefore, an acute dietary point of departure 

Infants and for the general U.S. population was not established. 

Children) 

UFA = lOX Acute RID = Prenatal Developmental Study (New 

Acute Dietary LOAEL = ur-11 = 1ox 0.0 1 Zealand White rabbits) 

(Females 13- 10 FQPA SF /UFL = mg/kg/day Developmental LOAEL = I 0 mg/kg bw 

49 years of based on skeletal variations (the 

age) mg/kg/day lOX aPAD = 0.01 

appearance of the 27'h presacral mglkglday vertebrae). 

Carcinogenicity (rat) 

LOAEL = 0.28/0.35 mg/kg/day (M/F) 

UFA = lOX Chronic RID based on a dose dependent increase in the 

Chronic LOAEL = UFH = lOX = 0.00028 incidence of opaque eyes and com eat 

Dietary (/\II 0.28 FQPA SF/UFt= mg/kglday damage in both sexes compared to 

Populations) mg/kg/day lOX cPAD = controls, an increased incidence of thyroid 

0.00028 follicular hyperplasia in males, and an 

mg/kg/day increased incidence of chronic 

progressive nephropathy in the kidneys of 

males. 

Dermal Short- LOAEL = Prenatal Developmental Study (New 

( 1-30 days) 10 UFA =lOX Occupational Zealand White rabbits) 

and Developmental LOAEL = I 0 mg/kg bw 

Intermediate- mg/kg/day UFII = lOX LOC for based on skeletal variations (the 

Term (1-6 OAF = Uh = lOX MOE = 1000 

appearance of the 27'h presacral 

months) 20.44% vertebrae). 

Inhalation Prenatal Developmental Study (New 

Shor1- ( 1-30 LOAEL = UFA= lOX Occupational Zealand White rabbits) 

days) and 10 Developmental LOAEL = I 0 mg/kg bw 

I ntcrmediate- mg/kg/day UFII = lOX LOC for based on skeletal variations (the 

Term (1-6 UFL = lOX MOE= 1000 

appearance of the 27'h presacral 

months) vertebrae). 

4 
Summary of Toxicologica l Doses and Endpoints for Bicyclopyrone for Use in Human Health Risk 

Assessments. 

RfD, PAD, 

Ex posure/ POD Unccrta inty/FQP LOC for Study and Toxicological Effects Scena rio A Safety Factors Risk 

Assessmen t 

Cancer (ora

Classi fie at ion: "Suggestive evidence of cancer" based on the presence of rare ocular tumors in 

dem1al, 

l, 

Assessment 

male rats. Quantification of bicyclopyrone's carcinogenic potential is not required. The Cancer 

inhalation) 

Review Committee (CARC) recommended using a non-linear approach (i.e., RfD) 

that will adequately account for all chronic toxicity, including carcinogenicity that could result 

from exposure to bicyclopyrone. 

used 

Point 

to 

of 

mark 

departure (POD)= A data point or an estimated point that is derived from observed dose-response data and 

the beginning of extrapolation to determine risk associated with lower environmentally 

exposures. LOAEL 

relevant human 

= lowest-observed adverse-effect 

animal 

level. UF = uncertainty factor. UFA = extrapolation !Tom 

(intraspec

to human (interspecies). UFH = potential variation in sensitivity among members of the human population 

population-adjusted 

ies). UFL = use of a LOAEL to extrapolate a NOAEL. FQPA SF = FQPA Safety Factor. PAD = 

Margin of Exposure. 

dose 

LOC

(a = acute, c = chronic). OAF= dermal absorption factor. RfD = reference dose. MOE = 

::: Level of Concern. 

The acute and chronic analyses assumed tolerance-level residues (acute analysis) or average field 

Since 

trial residues (chronic analysis), 100% crop-treated (CT), and modeled drinking water estimates. 

adequate processing studies have been submit1ed, which indicate that residues do not 

concentrate in corn or sugarcane commodities, the Dietary Exposure Evaluation Model (DEEM 

ver. 7.81 ) default processing factors for these commodities were reduced to I. The resulting 

91% 

acute 

chronic 

[2. 9% acute population-adjusted dose (aPAD) for females 13 - 49 years old] and chronic [:5 

population-adjusted dose (cPA D); children (I - 2 years old) were the most highly 

and 

exposed subgroup] dietary risk estimates are not of concern. The occupational handler exposure 

ma

risk estimates indicate that the short- and intermediate-term dermal and inhalation combined 

rgins of exposure (MOEs) are not of concern (i.e., MOE :::: 1000) with baseline attire (i.e., 

application 

single layer of clothing, no gloves, and no respirator; all MOEs :::: 1 ,700). The occupational postdermal exposure and risk estimates are greater than the level of concern of I 000 on 

the day of application, ranging from I ,800 to 49,000 depending on crop and activity. 

Assessment of Ecological Risk 

Bicyclopyrone 

expec

is a relatively soluble, nonvolatile compound that is stable to hydrolysis and is 

ted to be very highly mobile in soil. Bicyclopyrone photodegrades on surface soil, with 

half-live

multiple 

s ranging from 4- to 13-days. lt is slightly persistent in aerobic soil, metaboliz ing to 

organic transformation products and carbon dioxide. It is stable in anaerobic soil and 

anaerobic aquatic systems, and degrades very slowly in aerobic aquatic systems, with half-lives 

of 393 - 681 days. Bicyclopyrone photodegrades slowly in water, with half-lives of II to 75 

days. The new active ingredient is not expected to bioaccumulate in aquatic and terrestrial 

water 

organisms. Bicyc lopyrone may move to groundwater via leaching, and may move to surface 

bodies via spray drift and runoff of dissolved or sorbed residues. 

Bicyclopyrone 

fish (and 

is classified as slightly to practically non-toxic to freshwater and estuarine/mari ne 

to aquatic-phase amphibians for which freshwater fish serve as surrogates) as well as to 

freshwater invertebrates, but is moderately toxic to estuarine/marine invertebrates on an acute 

5 
exposure basis. Chronic effects were not observed in either the freshwater fish earl y life stage 

toxicity test or the freshwater invertebrate full life cycle test after exposure to bicyclopyrone. No 

chronic estuarine/marine fish or invertebrate studies were submitted and therefore acute-tochronic ratios (ACRs) based on freshwater species were used to estimate chronic toxicity 

endpoints for estuarine/marine animals. Toxicity to aq uatic vascul ar and non-vascular plants 

was observed upon exposure to bicyclopyrone. 

Bicyclopyrone is moderately to practically non-toxic to birds (and to terrestrial-phase 

amphibians and reptiles for which birds serve as surrogates), mammals, and to young adult 

honey bees (Apis mellifera) on an acute exposure basis. 

Risk quotients (RQs) do not exceed the acute or chronic risk levels of concern (LOCs) for both 

freshwater and estuarine/marine fish and invertebrates or for aquatic-phase amphibians. RQ 

values were also below LOCs for acute and chronic risk to birds, terrestrial-phase amphibians 

and reptiles and for acute risk to mammals. However, RQs exceed the LOC for chronic risk to 

mammals (RQs = I - 2.1 ). Consistent with the MoA of bicyclopyrone as an herbicide, exposure 

at the maximum labeled application rates may result in risk to terrestrial and semi-aquatic 

dicotyledenous (dicots) plants (RQs = 1.35 - 11.48). RQ values exceed the LOC for risk to 

federally listed threatened or endangered (referred to as "listed") dicots for pre-emergent use 

(RQs = 1.8 - 9.0) as well as for both listed and non-listed aquatic vascular plants. 

The following tables provide a comparison of the toxicity ofbicyclopyrone relative to alternative 

compounds for the proposed use on corn. These tables provide a comparison of toxicity data on 

a chemical-by-chemical basis; the tables are sorted with the most toxic herbicide (based on 

endpoint values) at the top and the least toxic at the bottom. Only groups of organisms for which 

LOCs are exceeded for bicyc lopyrone are listed. 

Vascular Aqua tic Plan ts EC~ d NOAECs 

C hemical EC~o NOAEC 

(mg/L) (mg/L) 

Acetochlor 0.0034 0.000 12 

Topramezone 0.0067 0.001 

Bicyclopy ronc 0.013 0.003 

Mesotrione 0.0177 0.0075 

S-metolach lor 0.048 0.0084 

Atrazinc 0.170 NA 

2,4-D 0.2992 NA 

Glyphosate 4.9 NA 

NA: Not ~'a1lable 

Terrestria l Pla nts NOAECs a nd ECB 

Chcm ical EC2s 2~ NOAEC 

(lbs ai/A) (lbs ai/A) 

Topramezone 0.0001 2 0.0000092 

Mcsotrione 0.00023 1 0.0001 1 

2,4-D 0.00081 1 0.000471 

Bicyclopyr onc 0.001 2 0.00022 

Acetochlor 0.0013 1 0.00061 

Atrazinc 0.003 1 0.00251 

6 
Benefits 

1 Based on seedling emergence study 1 Based on the vcgctntive vigor study 

0.0162 

M ammalian Chronic NOAECs and NOAELJ s 

Chemica l NOAELM 

(1111!/k!!-bW) 

Topramezone 0.2* 

Bicyclopy ronc 2. 15 

S-Mctolachlor 15* 

2,4-D 16.6 

Atrazine 25* 

Mesotrione 71.4 

Acetochlor 175 

Glyphosate 500 

0.0031 2 

NO AECN 

(me./ k!!-diet) 

4.0 

43* 

300 

332* 

500 

1428* 

3500* 

10000 

b

' The NOAEL and NOAEC arc used to estimate chron1 c dose-based and d1ctal)'· 

ased risk, respectively, to listed mammals. 

• Endpoint estimated based on the assumption that I mgfkg·bw = 20 mgfkg-dict 

Bicyclopyrone will initially be marketed as a four-active ingredient herbicide product 

(AcuronTM, 

metolachlor). 

also 

AcuronTM 

formulated with 2.60% mesotrione, 10.93% atrazine, and 23.40% Semergent appl

can provide its most effective weed management with a single preication that may not require additional post-emergent applications. 

me

Acu

tolachlo

ronTM will 

r

be labeled for difficult to control weeds with a lower rate ofatrazine, Sto corn as well 

, and mesotrione; resulting in decreases in the amount of atrazine that will be applied 

reductions as an 

as small er reductions in S-metolachlor and mesotrione. The agency views these 

growers' adoption 

environmental benefit. Because of the uncertainty in fully predicting future 

over time

of AcuronTM and ultimately whether growers will use less than labeled rates 

, as is common with the alternatives, 

reporting on herbicide 

the Agency is requiring submission of annual 

and 

use impacted by the introduction of Acuron TM. Syngenta will develop 

reductions 

implement an educational and stewardship program designed to achieve the predicted 

AcuronTM

in herbicide usc on corn. Finally, the agency and Syngenta will monitor the use of 

mit

, to ensure that significant reductions in the use ofatrazine occur. Additional 

igation measures would be adopted in the event that they do not. 

Public Comments 

registration 

On 8/13/14, 

o

EPA published a notice of receipt in the Federal Register of an application for 

were received

f bicyclopyrone and announced a public comment period of 30 days. No comments 

announcing 

. On 9/5/14, the EPA published a notice of filing in the Federal Register 

Federal Food

the receipt of the initial filing of the bicyclopyrone petition by Syngenta under the 

residues of bicyclopyr

, Drug, and 

o

Cosmetic Act (FPDCA) requesting the establishment of regulations for 

commen

ne on various commodities. This publication also announced a public 

Three of 

t 

the 

period 

com

of 

me

30 

nt

days; seven comments were received on the FFOCA notice of filing. 

other actions 

s were relevant to bicyclopyrone, the other four comments were relevant to 

that were batched together with bicyclopryone in the same Federal Register 

7 
document. The commenters noted that pesticides and bicyclopyronc pose a risk to pollinators. 

The agency has determined that bicyclopyrone is moderately to practically non-toxic to young 

adult honey bees (Apis mellifera) on an acute exposure basis. On 2/11 /20 15, the EPA published 

an additional notice of filing in the Federal Register for the import tolerance on sugarcane 

petition and no relevant comments were received. 

The EPA announced the proposed decision of the unconditional registration of bicyclopyrone on 

3/ 13115, and held a public comment period for 30 days, closing 4/13/15. Forty four submissions 

were received in response to the public commenting period. Forty one submissions were 

received from various universities, state corn grower associations, state agri-business 

associations, state farm bureaus, state food processors associations, IR-4, Syngenta, and the 

public and were in favor of and supported the registration of bicyclopyrone; noting its benefits of 

controlling hard to control weeds such as cockle burr, ragweed, etc., helping with herbicide 

resistance management, its ability to be used as part of a one-pass spray system, and reduction of 

the use of atrazine, S-metolachlor, and mesotrione. Three submissions were in opposition to the 

agency's proposed decision to register bicyclopyrone and based their concern on the agency not 

consulting with the U.S. Fish and Wildlife Service and National Marine fisheries Service under 

the Endangered Species Act and not having adequate label and use restrictions to protected listed 

species. One of the submissions in opposition to registration was a mail campaign submission 

containing 5,558 letters. EPA's review and responses are summarized in a separate response to 

public comments document and is available in the Docket (Docket ID: EPA-HQ-OPP-20 14-

0355). 

Mitigation and Labeling Requia·cments 

Because of the potential for leaching of bicyclopyrone and its degradates, labels have language 

including surface and ground water advisories that warn of the potential for runoff after 

treatment and descriptions of conditions that may be susceptible to leaching to groundwater. In 

order to mitigate risks, language is on the label that is intended to keep the pesticide on the 

intended treatment area, thereby reducing the potential for exposure to non-target organisms. 

For exan1ple, the following label language is on the end-use products, S YN-A 16003 Herbicide 

and AcuronTM Herbicide, which instructs users of applicator responsibilities and specific 

techniques to reduce the possibility of spray drift: 

Spray Drift Language 

SPRAY DRIFT 

Do not apply when weather conditions may cause drift to nontarget areas. Drift may result in 

injury to adjacent crops and vegetation. To avoid spray drift, DO NOT apply when wind speed 

is greater than i'O mph or during periods of temperature inversions. 

A VOIDING SPRAY DRIFT AT THE APPLICATION SITE IS THE RESPONSIBILITY OF 

TIIE APPLICATOR. 

8 
The 

The interaction of equipment and weather related factors determine the potential for spray drift. 

applicator is responsible for considering all these factors when making a decision. 

Information on Droplet Size 

The most effective way to reduce spray drift potential is to apply large droplets. Use only 

nozzles producing medium to ultra-course droplets. Do not use nozzles producing fine droplets. 

Controlling Droplet Size 

Volume - Use high flow rate nozzles to apply the highest practical spray volume. Nozzles with 

higher rated flows produce larger droplets. 

Pressure - Do not exceed the nozzle manufacturer's recommended pressures. For many nozzle 

types, lower pressure produces larger droplets. When higher flow rates are needed, use higher 

rate nozzles instead of increasing pressure. 

Number of Nozzles- Use the minimum number of nozzles that provide uniform coverage. 

Non-Target Areas 

Do not apply this pesticide when this product may drift to non-target areas. 

Application Height 

Applications must be made at the lowest height above the target area that still provides uniform 

of 

coverage of the target. Making applications at the lowest yet effective height reduces exposure 

droplets to wind. 

Wind 

Drift potential is lowest when wind speeds are I 0 mph or less. However, many factors, 

including droplet size, pressure, and equipment type determine drift potential at any given wind 

speed. Note: Local terrain can influence wind patterns. 

Leave a 25-foot buffer downwind of the application to avoid drift to non-target areas. 

Temperature Inversions 

Applications must not occur during a temperature inversion because drift potential is high. 

Temperature inversions restrict vertical air mixing, which causes small suspended droplets to 

variable 

remain in 

winds 

a concentrated cloud. This cloud can move in unpredictable directions due to the light 

common during inversions. Temperature inversions arc characterized by 

increasing temperatures with altitude and are common on nights with limited cloud cover and 

light to no wind. They begin to form as the sun sets and often continue into the morning. Their 

presence can be indicated by ground fog; however, if fog is not present, inversions can also be 

9 
identified 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 

verti cal air mixing. 

Environmental Hazards 

Do not apply directly to water, or to areas where surface water is present or to intertidal areas 

below the mean high water mark. Do not contaminate water when disposing of equipment 

washwater or rinsate. 

Ground Water Advisory 

Bicyclopyrone is known to leach through soil into groundwater under certain conditions as a 

result of label use. This chemical may leach into groundwater if used in areas where soils are 

permeable, particularly where the water table is shallow. 

Surface Water Advisory 

This product has a high potential for reaching surface water via runoff for several months or 

more 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 bicyclopyrone 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. 

Aerial Prohibition 

Do not apply by air. 

Data Requirements 

Data from the acute contact and oral toxicity tests with adult honey bees indicate that 

bicyclopyrone is practically non-toxic to bees on an acute exposure basis. However, at this time, 

there are no data regarding the potential acute and chronic effects of the compound on honey bee 

larval development and survival or the potential for chronic effects of adult bees. Therefore, 

EPA is requiring the submission of this information. This data requirement is explained further 

below. 

Annual Reporting 

AcuronTM's introduction will result in reduction in the use of other Syngenta products, resulting 

in a reduction of 3.6 million pounds of atrazine per year on acres that would of have been treated 

with those products. The agency is requiring Syngenta to achieve this reduction no later than the 

2020 growing season. 

10 
AcuronTM's 

Syngenta wi II provide an annual report to EPA no later than March 31 of each year following 

first full launch year (the first full launch year currently is anticipated 

and. if so, 

to be 2016 

total application 

the first 

of 

report would be made in March of 20 17). The report will include data on the 

In the annual 

specific herbicide products to corn grown in the U.S. in the preceding year. 

demonstrate 

report on the 2018 growing season (provided in March of2019) Syngenta will 

2020 growing 

a 

season 

1.6 million pound reduction of atrazine used per year. In the annual report on the 

(provided 

3.6 million 

in March of2021 ), Syngenta will demonstrate an approximately 

achieved, mitigation 

pound reduct

measures 

ion of atrazine used per year. In the event that these reductions are not 

will be undertaken to ensure that atrazine uses are reduced. 

International Harmonization 

There 

bicyclopyrone. 

arc no established 

Bicyclopyrone 

Mexican or Codex maximum residue limits (MRLs) for residues of 

APVMA. At 

is the subject of a global data review by the EPA, PMRA, and 

among the revi

this 

ew 

time, the residue definitions and the tolerances and MRLs are harmonized 

partners. 

Regulatory Decision 

In cooperation with our regulatory partners in Australia and Canada, and considering 

assessed 

the 

risk to human health and the environment, 

meets 

the agency concludes that bicyclopyrone 

the regulatory standard under FIFRA. Therefore, the EPA is granting a conditional 

to 

registration 

register bicyclopyrone 

ofbicyclopyrone under Section 3(c)(7)(C) ofFIFRA. The agency initially proposed 

as an unconditional 

requirement

registration 3(c)(5). However, due to the data 

conditional registration 

s for bicyclopyrone, concerning bees the agency is registering bicyclopyrone as a 

3(c)(7)(C). 

The database submitted to support the assessments of human health risk and environmental 

and ecological 

fate 

concern for human 

risk 

health. 

is adequate 

Bicyclopyrone 

to support the use and tolerances. There are no risk estimates of 

freshwater and 

has low potential for acute risk to mammals, birds, 

estuarine/marine fish, freshwater 

insects. Bicyclopyrone may 

invertebrates, amphibians, reptiles, and adult 

risk to non-human mammals. 

pose a risk to non-target terrestrial and aquatic plants, and chronic 

Requ

Label language as outlined in the "Mitigation and Labeling 

irements" section will reduce the risk to these organisms. 

and 

EPA is requiring acute and chronic studies of bieyclopyronc on honey bee larval development 

risk 

survival 

assessments 

and chronic studies of adult bees to support future, more comprehensive pollinator 

bicyclopyrone 

for bicyclopyrone. For the proposed usc on corn, any exposure to 

lower 

transported through the plant into pollen and/or nectar is expected to be much 

ecological 

than exposure from direct treatment of the crop, which is addressed in the current 

risk assessment. Additionally, 

of action as a HPPD 

there are no data to suggest that bicyclopyrone's mode 

inhibitor, which results in oxidative stress and chlorophyll 

cells, would have 

loss in plant 

a direct adverse effect on honey bee health. Therefore, this requirement 

consistent with 

is 

the harmoni zed Guidance for Assessing Pesticide Risks to Bees 

II 
(http://www2.epa.gov/sitcs/production/ lilcs/20 I+ 

06/documents/pollinator _ risk_assessment_guidance _ 06 _ 19 _ 14.pdf). However, for the use 

pallern currently proposed, the potential for adverse effects to adult honey bees from direct 

application is low and there is sufficent information to support a conditional risk-benefit 

decision. 

In accordance with 3(c)(7)(C) of FIFRA the agency has determined that registering 

bicyclopyrone is in the public interest. AcuronTM can control weeds with a single pre-emergent 

application that may not require additional post-emergent applications. AcuronTM will be labeled 

for difficult to control weeds with a lower rate of atrazine, S-metolachlor, and mesotrione; 

resulting in decreases in the amount of atrazine that will be applied to corn as well as smaller 

reductions in S-metolachlor and mesotrione. AcuronTM's penetration into the market will result 

in the reduction of other Syngenta atrazine products, resulting in a reduction of 3.6 million 

pounds of atrazine per year on acres that would have been treated with those products. 

The agency is registering the following five products: 

Bicyclopyrone Technical 

• 99.3% Bicyclopyrone 

• Only for formulation into an herbicide for usc in field corn, seed corn, silage com, sweet 

corn, and yellow corn. 

Bicyclopyrone Wet Paste Manufacturing Use Product 

• 94.0% Bicyclopyrone 

• Only for formul ation into an herbicide for use in field com, seed corn, silage corn, sweet 

corn, and yellow corn. 

Bicyclopyrone Wet Paste 11 Manufacturing Use Product 

• 89.6% Bicyclopyrone 

• Only for formul ation into an herbicide for use in field corn, seed corn, silage com, sweet 

corn, and yellow corn. 

SYN-A 16003 Herbicide 

• 18.5% Bicyclopyrone 

• Only for use as a pre-emergent and post-emergent herbicide for the selective contact and 

residual control of broad leaf weeds use in fi eld corn, seed corn, silage corn, sweet corn, 

and yellow com. 

Acuron TM Herbicide 

• 0.65% Bicyclopyrone, 2.60% Mesotri one, I 0.93% Atrazine, and 23.40% S-Metolachlor 

• Only for use as a pre-emergent and post-emergent herbicide for the selective contact and 

residual control of broad leaf weeds use in field corn, seed corn, silage corn, sweet com, 

and ye llow corn. 

In summary, bicyclopyrone is comparable to the other HPPD inhibitors and as stated above, this 

new active ingredient meets the regulatory standard under FIFRA. With the tetms and 

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conditions 

Herbicide 

of registration, the agency expects, and will ensure, that the availability of Acuron TM 

results in reductions in the amount of atrazine applied to corn in the U.S. The risk 

as

HQ-OPP-20 

sessments supporting this decision can be found in the regulatory docket (Docket ID: EPA14-0355. 

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