United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-96-006
March 1996
R.E.D. FACTS
Pesticide
Reregi strati on
Use Profile
Regulatory
History
Desmedipham
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 reregi strati on, EPA obtains and reviews a
complete set of studies from pesticide producers, describing the human health
and environmental effects of each pesticide. The Agency develops any
mitigation measures or regulatory controls needed to effectively reduce each
pesticide's risks. EPA then reregisters pesticides that can be used without
posing unreasonable risks to human health or the environment.
When a pesticide is eligible for reregi strati on, EPA explains the basis for
its decision in a Reregi strati on Eligibility Decision (RED) document. This fact
sheet summarizes the information in the RED document for reregi strati on case
2150, desmedipham.
Desmedipham is a selective postemergence herbicide used to control
various annual weeds. Desmedipham is Federally registered for use on sugar
beets. There is one Special Local Needs registration granted to the State of
Washington for use on table beet and Swiss chard seed production uses.
Formulations include emulsifiable concentrates and wettable powders.
Desmedipham is applied in spring by band treatment or broadcast method by
aircraft or groundsprayer. There is a 75 day preharvest interval.
Desmedipham was first registered as a pesticide in the U.S. in 1974.
Currently, there are 10 Federally registered desmedipham products. Data Call-
ins (DCI) were issued in 1991 and 1992 requiring data in support of
reregi strati on. An additional DCI for re-entry protection data and
mixer/loader/applicator exposure monitoring data for desmedipham products
was issued in March 1995.
Human Health Toxicity
Assessment In studies using laboratory animals, desmedipham generally has been
shown to be practically non-toxic for acute oral toxicity, inhalation toxicity and
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dermal irritation, and has been placed in Category IV (the lowest of four
categories) for these effects . It is slightly toxic for dermal exposure and has
been placed in Toxicity Category III for this effect. Desmedipham is
moderately toxic for eye irritation and has been classified as Category II.
Desmedipham is not considered a developmental toxicant or a mutagen.
Its cancer classification is Group E (evidence of non-carcinogenicity for
humans) pending receipt and evaluation of confirmatory data.
Dietary Exposure
People may be exposed to residues of desmedipham through the diet
from processed sugar and sugar products derived from sugar beets.
Tolerances have been established of .2 ppm in/on sugar beet roots and tops
(please see 40 CFR 180.353}. EPA has reassessed these desmedipham
tolerances and found them acceptable.
AgrEvo has petitioned the Agency to establish a tolerance for sugarbeet
tops at 15 ppm. The Agency must receive acceptable field trial data prior to
acceptance of this proposal. Available data indicate that residues of
desmedipham do not concentrate in processed food or feed; therefore, no food
or feed additive tolerances are established or required at this time. No
international Codex Maximum Residue Levels (MRLs) have been established
or proposed for desmedipham.
EPA has assessed the dietary risk posed by desmedipham. The
Anticipated Residue Concentration (ARC) for the overall U.S. general
population represents about 0.1 % of the Reference Dose (RfD), or amount
believed not to cause adverse effects if consumed daily over a 70-year lifetime.
The most highly exposed subgroup, non-nursing infants less than one year old,
has an ARC which represents 0.41% of the RfD. This low fraction of the
allowable RfD is considered to be an acceptable dietary exposure risk.
Occupational and Residential Exposure
Based on current use patterns, handlers (mixers, loaders, and applicators)
may be exposed to desmedipham during and after normal use of formulations
during application in agricultural settings. The Margins Of Exposure for
dermal exposure are of concern for occupational mixers/loaders. EPA is
requiring chemical-resistant gloves for all mixers and loaders. In addition, a
dust/mist respirator will be required for mixers/loaders of wettable powder
formulations who are supporting groundboom applications. To adequately
mitigate risks to mixers/loaders of wettable powder formulations who are
supporting aerial applications, EPA is requiring that the product must be
formulated in water-soluble packaging, or application rates must be limited to
no more than 0.5 Ib of active ingredient per acre on no more than 350 acres
treated per day. The Agency believes that implementation of the above
measures will adequately mitigate the potential risk identified in the risk
assessment.
Human Risk Assessment
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Desmedipham generally is of low acute and chronic toxicity. It poses a
very low risk from dietary exposure. The potential risk to handlers from
exposure may be adequately mitigated by appropriate use of Personal
Protective Equipment or engineering controls. Post-application reentry
workers will be required to observe a 24-hour Restricted Entry Interval.
Environmental
Assessment
Additional Data
Required
Environmental Fate
Although the environmental fate database is not complete, there is
sufficient acceptable and supplemental environmental fate information for the
Agency to conclude that desmedipham will not persist in the environment. The
primary degradation pathway for desmedipham is hydrolysis to ethyl-(3-
hydroxyphenyl) carbamate (EHPC) and aniline, with further degradation by
microbial processes to carbon dioxide. Photodegradation, volatilization,
and bioaccumulation in fish do not appear to contribute significantly to the
dissipation of desmedipham. Desmedipham and EHPC have a low potential to
leach to ground water in most soils. It is expected that desmedipham residues
which reach surface water by either spray drift or runoff will be rapidly
degraded.
Ecological Effects
The Agency has concluded that risk from desmedipham to aquatic plants
and animals is minimal, as is the acute risk to insects, birds, and mammals. The
Agency believes that chronic risk to mammals is also minimal, and that a
chronic risk to birds exists but is low to moderate. Effects are expected to be
limited in extent, and the impact to the environment should be signifcant only
on the local level. Risk to terrestrial and semiaquatic plants could not be
assessed because of lack of testing using a typical end-use product. To be
conservative, desmedipham is assumed to pose risk to these plants through
exposure from drift, however this risk is low and is addressed by labelling
changes.
EPA is requiring additional information to upgrade the following
supplemental submissions for desmedipham to confirm its regulatory
assessments and conclusions: General Metabolism, Hydrolysis, Anerobic soil
metabolism, Anaerobic aquatic metabolism, Terrestrial field dissipation,
Rotational crops (confined), Magnitude of the residue in plants (sugar beet
tops).
In addition, new studies using a typical end-use product are being
required for seedling emergence testing and a vegetative vigor test. 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 reregi strati on.
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Product Labeling
Changes
Required
Regulatory
Conclusion
For More
Information
The minimum PPE for occupational uses of desmedipham end-use
products is long-sleeved shirt and long pants, chemical-resistant gloves, shoes
plus socks for all formulations. In addition, for wettable powder formulations,
a dust/mist filtering respirator must be used. Wettable-powder formulated
products must be contained in water-soluble packaging when applied aerially
(unless the application rate used is no more than 0.5 pounds active ingredient
per acre, assuming aerial applications of up to 350 acres per day). A 24-hour
restricted-entry interval is required. For early entry into a treated field,
workers must wear coveralls, chemical-resistant gloves, shoes plus socks, and
protective eyewear.
The use of currently registered products containing desmedipham in
accordance with approved labeling will not pose unreasonable risks or adverse
effects to humans or the environment. Therefore, all uses of these products are
eligible for reregi strati on.
Desmedipham products will be reregistered once the required product-
specific data, revised Confidential Statements of Formula, and revised labeling
are received and accepted by EPA. The use of eligible desmedipham products
in accordance with labeling specified in this RED will not pose unreasonable
adverse effects to humans or the environment. These products will be
reregistered once the required confirmatory generic data, product specific data,
CSFs, and revised labeling are received and accepted by EPA. Products which
contain active ingredients in addition to desmedipham will be reregistered
when all of their other active ingredients also are eligible for reregi strati on.
EPA is requesting public comments on the Reregi strati on Eligibility
Decision (RED) document for desmedipham during a 60-day time period, as
announced in a Notice of Availability published in the Federal Register. To
obtain a copy of the RED document or to submit written comments, please
contact the Pesticide Docket, Public Response and Program Resources
Branch, Field Operations Division (7506C), Office of Pesticide Programs
(OPP), US EPA, Washington, DC 20460, telephone 703-305-5805.
Electronic copies of the RED and this fact sheet can be downloaded
from the Pesticide Special Review and Reregi strati on Information System at
703-308-7224. They also are available on the Internet on EPA's gopher
server, GOPHER.EPA.GOV, or using ftp on FTP.EPA.GOV, or using WWW
(World Wide Web) on WWW.EPA.GOV.
Printed copies of the RED and fact sheet can be obtained from EPA's
National Center for Environmental Publications and Information
(EPA/NCEPI), PO Box 42419, Cincinnati, OH 45242-0419, telephone 513-
489-8190, fax 513-489-8695.
Following the comment period, the desmedipham RED document also
will be available from the National Technical Information Service (NTIS),
5285 Port Royal Road, Springfield, VA 22161, telephone 703-487-4650.
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For more information about EPA's pesticide reregi strati on program, the
desmedipham RED, or reregi strati on of individual products containing
desmedipham, please contact the Special Review and Reregi strati on Division
(7508W), OPP, US EPA, Washington, DC 20460, 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 Pesticides Telecommunications Network (NPTN). Call toll-free 1-
800-858-7378, between 9:30 am and 7:30 pm Eastern Standard Time, Monday
through Friday.
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