United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508C)
EPA738-F-04-010
September 2004
&EHV R.E.D. FACTS
Pesticide
Reregistration
Thiram
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
safely 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
0122, thiram.
Use Profile Thiram is a non-systemic fungicide used to prevent crop damage in the
field and to protect harvested crops (apples, peaches, and strawberries) from
deterioration in storage or transport. It is also used as a seed protectant (e.g. small
seeded vegetables, large seeded vegetables, cereal grains and other seeds,
coniferous seeds, cotton seed, ornamental seeds, and soybeans) and to protect turf
from fungal diseases. In addition, thiram is used as an animal repellent to protect
crops from damage by rabbits, rodents, and deer. Formulations include dust,
wettable powder, water dispersable granule, flowable concentrate, dry flowable,
soluble concentrate, and ready-to-use liquid. Thiram is applied to seeds prior to
planting both by commercial seed treaters and on-farm applicators.
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Regulatory
History
Human Health
Assessment
Approximately 165,000 pounds of thiram are applied to 35,000 acres of
strawberries, apples, and peaches annually. Approximately 631,000 pounds of
thiram are used to treat approximately 1.3 billion pounds of seed annually.
Thiram has been registered in the United States since 1948 for use as a
non-systemic, protectant dithiocarbamate fungicide. During the second phase of
reregistration, the Agency conducted a review of the scientific data base
underlying pesticide registrations and identified missing or inadequate studies.
Subsequent Data Call-ins (DCIs) were issued in 1991 and 1995 for thiram.
Toxicity
Thiram exhibits low to moderate acute toxicity via the oral (Toxicity
Category III) and dermal (Toxicity Category HI) routes of exposure. Thiram is
considered to be moderately toxic via the inhalation route of exposure (Toxicity
Category II). It is a moderate eye irritant (Toxicity Category II), a slight dermal
irritant (Toxicity Category IV) and a moderate skin sensitizer.
Thiram is a neurotoxicant and can also act as a developmental toxicant.
The neurotoxic effects of thiram seen in laboratory animals include lethargy and
reduced motor activity. Developmental effects seen in laboratory animals include
severe fetal malformations. In carcinogenicity studies in rats and mice, thiram did
not demonstrate any significant evidence of carcinogenic potential.
Dietary Exposure (Food and Water)
People may be exposed to residues of thiram through the diet. Tolerances
or maximum residue levels have been established for apples, peaches, and
strawberries. The registrant voluntarily agreed to halt after December 31, 2004,
the distribution or sale of any thiram product bearing a label that includes uses on
strawberries, unless and until EPA has determined certain conditions are satisfied.
Please refer to the Dietary Risk Mitigation section for further discussion.
EPA has assessed the dietary risk posed by thiram. Acute risks from
aggregate exposures are not of concern due to removal of strawberries from the
label, a voluntary request for cancellation of apple uses, and requests for
voluntary cancellation of most residential uses. Models have been used to
estimate ground and surface water concentrations. The Agency concludes with
reasonable certainty that aggregate exposure to food and drinking water will not
result in an unacceptable acute, short-term, or chronic risk.
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Occupational and Residential Risk
Residential Risk. Thiram will no longer be available for sale or use by
homeowner applicators. As such, all residential risks were calculated related to
the non-residential turf uses that include golfing for adults and toddler exposures
in areas that can be treated with thiram by certified pesticide applicators. Margins
of-Exposure (MOEs) for golfers are not of concern to the Agency, and therefore
no risk mitigation measures are required to address this scenario. To protect
children from potential exposure to thiram treated turf and to further protect
from exposure to ornamentals treated with thiram as a deer repellent, the
Agency is requiring mitigation measures outlined below.
Occupational Risk. The Agency calculated the potential exposure and
risk to pesticide handlers from 28 major occupational exposure scenarios.
Worker risk is measured by an MOE, which determines how close the
occupational exposure comes to the No-Observed-Adverse-Effect-Level
(NOAEL) taken from an animal study. A MOE of 100 or greater, for both the
dermal and inhalation route is considered to be protective for thiram.
Occupational exposure and risk estimates were conducted using maximum
application rates and high-end assumptions. The results of the worker exposure
assessment indicate that most potential exposure scenarios result in MOEs greater
than or equal to the target MOE of 100 for dermal and inhalation for all of the
seed crops treated with thiram products being actively sold in the U.S.
Workers can also be exposed to thiram residues by entering previously
treated areas to perform activities. The Restricted Entry Interval (REI) is used by
the Agency to manage risks for postapplication workers doing activities that
require contact with treated surfaces. The REI is the amount of time required
after application before residues decline to a level so entry into the treated area
and engaging in any task or activity would not result in exposures which are of
concern. Current labels for thiram specify an REI of 24 hours. Current REIs are
protective for most crops, however risks for reentry workers are of concern for
very high exposure activities. The number of days required for MOEs to reach
the Agency's level of concern MOE of 100 is two days for peach thinning on the
East coast. Risks are a concern for high exposure activities such as transplanting
and hand weeding sod (MOEs>100 at 12-21 days). The Agency has no concern
with maintaining the current REI of 24 hours because the apple use has been
voluntarily cancelled, and the MOE for peaches is almost 100 (i.e., 94 after 24
hours).
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FQPA Considerations
No Special FQPA Safety Factor is necessary to protect the safety of infants
and children because there is no quantitative or qualitative evidence of increased
susceptibility following in utero or postnatal exposure in any of the
developmental or reproductive studies, and the toxicity endpoints selected are
protective of pre/postnatal toxicity following acute and chronic exposures.
Thiram is classified as "not likely to be carcinogenic to humans " according
to the EPA Draft Proposed Guidelines for Carcinogen Risk Assessment (July 2,
1999).
Environmental Environmental Fate
Assessment Thiram is expected to be sufficiently mobile and persistent in some cases to
reach surface waters in concentrations high enough to impact aquatic life.
Ecological Effects
Mammals and birds in the field may be exposed to thiram by ingesting
treated seeds or by other routes, such as incidental ingestion of contaminated soil,
dermal contact with treated seed surfaces and soil during activities in the treated
areas, inhalation of pesticide vapor and contaminated particulate, and ingestion of
drinking water contaminated with the pesticide.
The ecological risk assessment for birds shows risks for reproductive
effects to birds. There is a chronic effect to mammals including endangered
species, and for fish and aquatic invertebrates including endangered species. Risk
quotients range from 0.1 to 28. The Agency's assessment suggested that a
number of endangered species may potentially be impacted by thiram; however,
this RED includes only risk mitigation for the Attwater's Prairie Chicken
(Tympanuchus cupido attwateri). The mitigation measures contained in the RED
address the Agency's ecological risks of concern.
The Agency has developed the Endangered Species Protection Program to
identify pesticides whose use may cause adverse impacts on endangered and
threatened species, and to implement mitigation measures that address these
impacts. As discussed above, Agency estimates of exposure indicate risks of
reproductive effects to endangered species of birds. The foliar and turf uses of
thiram may pose an acute risk to endangered fish and invertebrate species, and a
chronic risk to endangered mammalian species. However, based on the
ecological risk assessment conducted for thiram and implementation of the
mitigation procedures described in the RED, EPA has determined that thiram will
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have no effect on the Attwater Prairie Chicken. Relating to any additional
endangered species concerns, these findings are based solely on EPA's screening
level assessment and do not constitute "may affect" findings under the
Endangered Species Act.
Based on information provided by the U.S. Fish and Wildlife Service, the
endangered species profile, and communications with refuge managers, the
Attwater's Prairie Chicken (Tympanuchus cupido attwateri) may be at risk for
consuming thiram-treated seed.
Risk Mitigation Dietary Risk Mitigation
The Agency has worked with the registrant, Taminco, Inc. (Taminco), to
reduce potential exposure to thiram from treated strawberries and apples.
Subsequently, Taminco has requested voluntary cancellation of thiram use on
apples and will amend its registration to remove strawberries from its label
pending receipt, review, and acceptability of additional data (a strawberry
processing study and a Developmental Neurotoxicity Study). The percent of
the aPAD considering dietary contributions from strawberries and peaches
only is 273. Without strawberries, the percent of the aPAD is reduced to 9.
To further reduce dietary concerns, the Agency has determined that the
following label changes for specific scenarios are appropriate and required for
reregistration eligibility:
• "Treated [Seed, Bulbs, Seed Pieces] - Do Not Use for Food, Feed, or Oil
Purposes."
Drinking Water Risk Mitigation
As previously discussed above, the acute, short-term and chronic risks
from aggregate exposures are not of concern to the Agency and no further
mitigation is necessary.
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Residential Risk Mitigation
To protect children from scenarios of concern (MOE=4) for exposure to
thiram treated turf) and to further protect from exposure to ornamentals treated
with thiram as a deer repellent, the Agency is requiring the following label
modifications:
Deer Repellent Use:
Use one quart of this product in 3 to 7 gallons of water for application to
1000ft2.
Applications to ornamentals will be restricted to the following 17
Northern states and applications will occur during the winter season only
(October thru March): OH, PA, NY, MI, CT, MA, IN, IL, NJ, WV,
MN, WI, VT, NH, RI, DE, and MD.
Cancellations of Turf/Other Uses:
Turf applications to parks, athletic fields and commercial landscapes.
All turf applications for turf grown for sale or other commercial use such
as sod.
• All homeowner and retail uses on residential lawns and turf
• Residential homeowner use as a fungicide on bulbs, flower seeds,
greenhouse and nursery cuttings, and pruning paints.
Through these label amendments and voluntary cancellations to remove
all homeowner uses from Taminco, the Agency believes exposure to the deer
repellent use will be insignificant and therefore not of concern. No additional
mitigation is necessary.
Occupational Risk Mitigation
Handler exposure
To reduce worker exposure, the Agency has determined that the following
label changes for specific scenarios are appropriate and required for reregistration
eligibility:
• Mixers/Loaders/Applicators/Other Handlers (general): wear baseline (long-
sleeve shirt, long pants, shoes, socks, no respirator) plus chemical resistant
gloves for the following scenarios (mixer/loaders wear a chemical resistant
apron):
liquids or dry flowables applied aerially
liquids, dry flowables or sprays applied via airblast
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liquids, dry flowables or sprays applied via groundboom
• liquids or dry flowables applied via a high pressure handwand
• liquids or dry flowables applied for rights of way
liquids applied as a paint-on application
solid broadcast spreader
• repellent paint brush use
• sprinkler can
ready-to-use solutions
wettable powder paint-on
• dry flowable paint-on
• Mixers/loaders/applicators/other handlers (packaged seed): seed that has
been treated with this product that is then packaged or bagged for future
use must bear labeling that contains the restricted-entry interval (REI)
information and the following text on the outside of the seed package or
bag: "Persons opening this bag or loading/pouring the treated seed, must
wear long-sleeved shirt, long pants, shoes, socks, and chemical resistant
gloves."
• Flaggers: wear baseline (long-sleeve shirt, long pants, shoes, socks, no
respirator for the following scenarios:
• sprays applied aerially
In addition to the above mentioned PPE requirements, the registrant has
agreed to the following use modifications/amendments to further address the
Agency's concerns:
• Cancellation of the aerial and hand/spoon applications
• Changing all wettable powder formulations to water soluble bag
formulations.
• Cancellation of on-farm seed treatment of peanuts
The following mitigation addresses the risks of concern for high exposure
activities associated with apples and sod:
Cancellation of all turf applications for turf grown for sale or other
commercial use such as sod.
Cancellation of all apple uses.
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Post-Application Risk Mitigation
EPA has determined that the current 24 hour REI is appropriate, and labels
must contain the following language to be eligible for reregistration:
"After the [seeds, bulbs, seed pieces] have been planted, do not enter or
allow worker entry into treated areas during the restricted-entry interval (REI) of
24 hours. Exception: Once the seeds, bulbs, seed pieces are planted in soil or
other planting media, the Worker Protection Standard allows workers to enter the
treated area without restriction if there will be no worker contact with the [seeds,
bulbs, seed pieces]."
Environmental Risk Mitigation
To reduce risks to mammals, birds, and aquatic species, the Agency, in
agreement with the technical registrants of thiram, has developed several
mitigation requirements to address the above mentioned concerns (mitigation
measures concerning strawberries are contingent upon if EPA determines that one
or more of the uses on strawberries is/are not eligible for reregistration). They
include:
A statement added to the label "Treated [seeds, seed pieces, bulbs] are
hazardous to fish, birds and mammals. Do not plant treated seeds or seed
pieces by broadcasting to the soil surface. Ensure that all [seeds, seed
pieces, bulbs] are thoroughly covered with soil, especially in turn areas.
If [seeds, seed pieces, bulb] are not thoroughly incorporated by the planter
during planting, additional incorporation may be required to thoroughly
cover exposed [seeds, seed pieces, bulbs]."
• A statement added to the label: "This chemical is toxic to fish, aquatic
invertebrates, oysters, and shrimp. Do not apply directly to water, or to
areas where surface water is present or to intertidal areas below the mean
high water mark. Drift and runoff from treated areas may be hazardous to
aquatic organisms in neighboring areas. Do not contaminate water when
cleaning equipment or disposing of equipment washwaters or rinsate."
• Cancellation of thiram use on apples.
Restriction of thiram use on golf courses to tees and greens only.
• Reduction of the winter golf course treatment from a maximum of four
applications to a maximum of one application.
• Reduction of summer golf course treatment from a maximum of eight
applications to a maximum of three applications.
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Restrict the number of annual applications of thiram to golf courses to 47
pounds of active ingredient per acre (this corresponds to a 40% total
reduction in thiram use on golf courses).
For the golf course use, increase the re-treatment interval from 7 to 14
days.
• For strawberries, limit the maximum number of applications to five at 2.6
Ibs ai/Acre.
• For strawberries, East of the Mississippi River, limit the maximum number
of applications to twelve at 2.6 Ibs ai/Acre.
For strawberries, add a label statement to indicate that 1.3 Ibs ai/Acre
should be used when thiram is used in combination with other fungicides.
For strawberries, the label will establish a 25 foot vegetative buffer zone
from water bodies.
For cotton, reduce the maximum treatment rate for cotton seed from 2.25
oz. ai/cwt (1406 ppm) when treated with thiram as a single active
ingredient to 1.6 oz. ai/cwt (1,000 ppm) reflecting the global use rate for
thiram on imported and exported cotton seed.
• For cotton, reduce the maximum treatment rate for cotton seed for thiram
in products containing multiple active ingredients to 1.0 oz. ai/cwt (625
ppm).
For cotton, wheat, barley, oats, and sugar beets include the statement plant
seed a minimum of 1 inch deep.
Upon examining the risks and requiring the above listed mitigation
measures, the Agency believes that concerns noted in Chapter 3 and above have
been adequately mitigated. No further mitigation is needed at this time.
In conjunction with other local and federal agencies, EPA will continue to
evaluate whether currently identified and/or additional endangered species may be
impacted by exposure to thiram.
Additional Data EPA requires additional generic studies for thiram to confirm its regulatory
Required assessments and conclusions.
Most product chemistry data requirements are satisfied; however,
additional data are required for Prochimie 98.5% Technical and Gustafson 97.5%
Technical, and Prochimie 98.5% Technical. Please refer to Appendix E of the
RED for a complete list.
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The Agency is uncertain regarding the endocrine disrupting potential of
thiram and, once the appropriate testing protocols have been established for
examining endocrine disruption, thiram may be subject to this battery of tests.
Product Labeling All thiram end-use products must comply with EPA's current pesticide
Chanqes Required product labeling requirements and with the following. For a comprehensive
list of labeling requirements, please see the thiram RED document.
Regulatory
Conclusion
For More
Information
The use of currently registered products containing thiram 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 reregistration.
Thiram products will be reregistered once the required product-specific
data, revised Confidential Statements of Formula, and revised labeling are
received and accepted by EPA.
To obtain a copy of the RED document or to submit written comments,
please contact the Pesticide Docket, Public Information and Records Integrity
Branch, Information Resources and Services Division (7502C), Office of
Pesticide Programs (OPP), US EPA, Washington, DC 20460, telephone
703-305-5805.
Electronic copies of the RED and this fact sheet are available on the
Internet. See http://www.epa.gov/REDs.
Printed copies of the RED and fact sheet can be obtained from EPA's
National Service Center for Environmental Publications (EPA/NSCEP), PO
Box 42419, Cincinnati, OH 45242-2419, telephone 1-800-490-9198; fax 513-
489-8695.
Following the comment period, the thiram RED document also will be
available from the National Technical Information Service (NTIS), 5285 Port
Royal Road, Springfield, VA 22161, telephone 1-800-553-6847, or 703-605-
6000.
For more information about EPA's pesticide reregistration program, the
thiram RED, or reregistration of individual products containing thiram, please
contact the Special Review and Reregistration Division (7508C), 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
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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://npic.orst. edu.
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