United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508C)
EPA-738-F-04-009
September 30, 2004
v-xEPA R.E.D. FACTS
Pesticide
Reregistration
Cycloate
All pesticides sold or distributed in the United States must be registered by
EPA, based on scientific studies showing that they can be used without posing
unreasonable risks to people or the environment. Because of advances in
scientific knowledge, the law requires that pesticides which were first registered
before November 1, 1984, be reregistered to ensure that they meet today's more
stringent standards.
In evaluating pesticides for reregistration, EPA obtains and reviews a
complete set of studies from pesticide producers, describing the human health
and environmental effects of each pesticide. To implement provisions of the
Food Quality Protection Act of 1996, EPA considers the special sensitivity of
infants and children to pesticides, as well as aggregate exposure of the public to
pesticide residues from all sources, and the cumulative effects of pesticides and
other compounds with common mechanisms of toxicity. The Agency develops
any mitigation measures or regulatory controls needed to effectively reduce each
pesticide's risks. EPA then reregisters pesticides that meet the safety standard of
the FQPA and can be used without posing unreasonable risks to human health or
the environment.
When a pesticide is eligible for reregistration, EPA explains the basis for its
decision in a Reregistration Eligibility Decision (RED) document. This fact sheet
summarizes the information in the RED document for reregistration case 2125,
cycloate (-S'-ethyl cyclohexyl(ethyl)thiocarbamate).
Use Profile
Cycloate is a broad-spectrum, pre-emergent herbicide registered for the
control of annual grasses, certain perennial grasses and many broadleaf weeds on
garden beets, spinach and sugarbeets. The Agency has found that the current uses
of cycloate on garden beets, spinach and sugarbeets are eligible for reregistration,
provided the changes specified in the RED are made to the cycloate labels. A new
use on Swiss chard has been proposed by the IR-4 program. Cycloate is not for
homeowner/garden use.
Sugarbeets account for more than 90% of cycloate usage. EPA estimates that
approximately 679,000 pounds of active ingredient (a.i.) are used annually on a total
of approximately 288,000 acres. Spinach accounts for almost 7% of cycloate usage
with 45,000 pounds of a.i. applied per year on average. Garden beets receive about
17,000 pounds of a.i. annually on just under 8,000 acres treated, nearly 100% crop
treated on garden beet acres.
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Regulatory
Hiistory
Cycloate is formulated as an emulsifiable concentrate liquid (73.9% a.i.).
Cycloate is typically applied using groundboom equipment and then incorporated
into the soil mechanically or by sprinkler irrigation (chemigation).
Cycloate was first registered in the United States on July 13, 1967, for use as a
selective herbicide on sugarbeets and spinach by the Stauffer Chemical Company.
The use of cycloate on garden beets was first approved on January 9, 1970. Stauffer
Chemical Company transferred the cycloate registrations to ICI Americas, Inc. on
December 23, 1987. On January 24, 1994, the registrant name was changed to
Zeneca Agrochemicals. Zeneca Agrochemicals merged with Novartis Agribusiness
in November 2000 to form Syngenta Crop Protection, Inc. Syngenta Crop
Protection, Inc. sold all proprietary rights for cycloate to TRIAQ Inc. on December
1, 2000. Helm Agro US, Inc. is the agent for TRI AQ Inc.
Cycloate was the subject of a Registration Standard Guidance Document
issued on December 7, 1988 and the Residue Chemistry Science Chapter of the
Guidance Document (Phase 4 reviews of available residue chemistry data) was
issued on December 20, 1990. These documents summarized the regulatory
conclusions based on available residue chemistry data and specified the updated
generic and product-specific chemistry data required by the Agency to support the
continued use of cycloate. In addition to the data requirements in the 1988 Guidance
Document, Data Call-in (DCI) notices were issued on April 5, 1991 and October 18,
1995. The data received in response to the DCIs were used to reach the
reregistration eligibility conclusions for cycloate presented in the RED.
Human Health Toxicity
Risk Assessment Cycloate has a low order of acute toxicity via the oral (Category HI), dermal
(Category IV) and inhalation (Category IV) routes of exposure. It is a moderate eye
and dermal irritant (Category HI) and is also a dermal sensitizer.
Cycloate is classified as "not likely to be a carcinogen to humans," therefore,
no assessments were performed for cancer.
Cumulative Risk
The Agency has determined that some thiocarbamates (EPTC, molinate,
pebulate and cycloate) share a common mechanism of toxicity, the inhibition of
acetylcholinesterase. In September 2001, the Scientific Advisory Panel (SAP)
concluded that there is insufficient evidence for grouping the thiocarbamate
pesticides based on a common mechanism of toxicity for effects other than
acetylcholinesterase inhibition.
The Agency conducted a preliminary "screening level" cumulative food risk
assessment for the thiocarbamates. The results of this assessment, using very
conservative Tier 1 exposure assumptions, is that MOEs exceed 310 for all
population subgroups. Any MOE greater than 100 is deemed acceptable by EPA.
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Therefore, at this time, EPA concludes that the potential cumulative risks from the
thiocarbamates in general and cycloate in particular passes the "reasonable certainty
of no harm" standard of the FQPA.
For information regarding EPA's efforts to determine which chemicals have a
common mechanism of toxicity and to evaluate the cumulative effects of such
chemicals, see the policy statements released by OPP concerning common
mechanism determinations and procedures for cumulating effects from substances
found to have a common mechanism at http://www. epa. sov/pesticides/cumulative.
Dietary Risks
No population subgroup, including infants and children, exceeded the
Agency's level of concern for either acute or chronic dietary exposure to cycloate
based upon aggregated exposure to food plus water.
Occupational and Residential Risks
The Agency has determined that there is a potential for short- and
intermediate-term exposures in occupational settings from handling cycloate products
during the application process (i.e., mixer/loader, applicator and
mixer/loader/applicator). Short- and intermediate-term dermal risk estimates for most
scenarios exceed the Agency's level of concern at baseline personal protective
equipment (PPE). However, most of these exposures can be mitigated by some level
of PPE and/or engineering controls. Risk estimates from inhalation exposures remain
a concern for most scenarios, even with maximum PPE and/or engineering controls.
Mitigation measures include the voluntary cancellation of the chemigation application
of cycloate, requiring engineering controls (including closed cabs and closed
mixing/loading systems), prohibiting on-farm impregnation of cycloate onto dry bulk
fertilizer, and requiring use data to better characterize exposure from dry bulk
fertilizer applications.
Post-application exposures are expected to be negligible because cycloate is
incorporated into the soil either immediately or within a few hours after application,
or it is injected into the soil. As a result, post-application scenarios were not assessed.
However, due to the volatility of cycloate, the REI will be extended from the current
12 hours to 48 hours. However, workers will be allowed to enter the treated area
during the first 48 hours following application to plant crops, provided they follow
the early reentry language on the label.
Cycloate is not registered for any residential (home/garden) or other
nonoccupational use, nor is it to be used in or around public buildings, schools or
recreational areas where children or others might be exposed. Thus, there is no
residential exposure to aggregate with the dietary exposure.
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Environmental
Risk Assessment
Ecological Risks
Cycloate use on garden beets, spinach and sugarbeets may cause adverse
ecological effects at the current maximum application rate of 4 Ibs. a.i./acre. Chronic
risks are potentially a concern for small mammals, birds and estuarine/marine fish and
invertebrates. Based on the Agency's screening level assessment, levels of concern
have been exceeded for endangered species of small mammals (chronic risk) and
potentially for birds (chronic risk). These findings are based solely on EPA's
screening level assessment and do not constitute "may affect" findings under the
Endangered Species Act.
Currently, the Agency does not have data to determine the risk from cycloate
use on spinach near estuarine areas to nontarget terrestrial plants. In addition, no
acceptable chronic avian reproduction data were available, so chronic risks for avian
species could not be assessed. Data are required to address these gaps in the
ecological assessment.
Risk Mitigation Pesticide mixer, loader and applicator risks will be mitigated by a combination
of increased personal protective equipment, use of engineering controls and revised
label language. Specifically, the following mitigation measures will reduce risks to
agricultural workers:
• Voluntary cancellation of chemigation application of cycloate;
• Require engineering controls including closed cabs and closed mixing/loading
systems;
• Prohibit on-farm impregnation of cycloate onto dry bulk fertilizer;
• Require use data to better characterize exposure from dry bulk fertilizer
applications; and
• Extend the cycloate REI to 48-hours.
The registrant has agreed to submit data on cycloate that will allow the
Agency to adequately assess the ecological effects of cycloate, thus refining these
risk estimates. The Agency reserves the right to impose environmental risk
mitigation strategies for cycloate, once these data have been reviewed.
Additional Data
Required
EPA is requiring the following confirmatory data requirements for cycloate
to confirm its regulatory assessments and conclusions: stability on TGAI;
ultraviolet/visible absorption; solubility; field accumulation in rotational crops;
terrestrial field dissipation; estuarine/marine fish and aquatic invertebrate acute
toxicity studies on TGAI; freshwater fish early life stage test on TGAI; freshwater
invertebrate life cycle test on TGAI; avian reproduction test (bobwhite quail and
mallard duck) on TGAI; seedling germination/emergence and vegetative vigor,
Tier 1 on TEP; aquatic plant growth, Tier 2 on TEP; multiresidue methods (3-
and 4-HC metabolites); and developmental neurotoxicity study on rats.
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The Agency also is requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of Formula
(CSFs) and revised labeling for reregistration.
Product Labeling All cycloate end-use products must comply with EPA's current pesticide
Chanaes Reauired Pr°duct labeling requirements, with the risk mitigation measures discussed above.
For a comprehensive list of labeling requirements, please see the cycloate RED
document.
Regulatory
Conclusion
The use of currently registered products containing cycloate in accordance
with approved labeling will not result in unreasonable adverse effects to humans
and the environment. The Agency, therefore, finds that all products containing
cycloate as the active ingredient are eligible for reregistration provided specified
changes are made to the label and additional data identified above confirm this
conclusion.
Cycloate products will be reregistered once the required product-specific
data, revised Confidential Statements of Formula, and revised labeling are
received and accepted by EPA.
For More
Information
EPA is requesting public comments on the Reregistration Eligibility
Decision (RED) document for cycloate during a 60-day time period, as
announced in a Notice of Availability published in the Federal Register. The
public may access this Federal Register document electronically through the EPA
Internet under the "Federal Register" listings at http://www.epa.sov/fedrKatr/. To
obtain a copy of the RED and supporting documents for cycloate or to submit
written comments, please contact the OPP Public Regulatory Docket, Public
Information and Records Integrity Branch (PIRIB) (7502C), Office of Pesticide
Programs (OPP), Environmental Protection Agency, 1200 Pennsylvania Avenue,
NW., Washington, DC 20460-0001, Attention: Docket ID Number OPP-2002-0234.
The docket telephone number is 202-305-5805.
To access electronic copies of the Agency's RED and supporting
documents for cycloate, go directly to the REDs table on the EPA Office of
Pesticide Programs Home Page, at
http://www.epa.sov/iKsticides/reresislralion/slalus.hlm. An electronic version of the
public docket is also available to the public through EPA's electronic public
docket and comment system, EPA Dockets. The public may use EPA Dockets at
http:/7www. ena.sov/edockets to submit or view public comments, access the index
listing of the contents of the official public docket and to access those documents in
the public docket that are available electronically. Once in the system, select
"search," then key in docket ID number OPP-2004-0234. Earlier information on
cycloate, including public comments, can be found in EPA Dockets under docket ID
number OPP-2004-0077.
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For more information about EPA's pesticide reregistration program, the
cycloate RED or reregistration of individual products containing cycloate, please
contact the US EPA, OPP, Special Review and Reregistration Division (7508C),
Washington, DC 20460-0001, telephone 703-308-8000.
For information about the health effects of pesticides, or for assistance in
recognizing and managing pesticide poisoning symptoms, please contact the
National Pesticide Information Center (NPIC). Call toll-free 1-800-858-7378,
from 6:30 am to 4:30 pm Pacific Time, or 9:30 am to 7:30 pm Eastern Standard
Time, seven days a week. Their internet address is http://www. npic. orst. edu.
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