United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-94-002
February 1994
R.E.D. FACTS
Pesticide
Reregistration
Methiocarb
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 years ago 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. The Agency imposes
any regulatory controls that are needed to effectively manage 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 reregistration, EPA announces this and
explains why in a Reregistration Eligibility Decision (RED) document. This
fact sheet summarizes the information in the RED for methiocarb.
Use Profile
Methiocarb is an insecticide, acaricide and molluscicide. It is used to
control snails, slugs, spider mites and insects on lawns, turf and
ornamentals, around building foundations, and in ginseng gardens.
Methiocarb has no remaining food uses; the use on ginseng has a 12-month
preharvest interval and therefore is not considered a food use.
Methiocarb end-use products formulated as granulars and
pellets/tablets are used on residential and commercially grown lawns,
turfgrass and ornamentals, in commercial greenhouses and nurseries, around
building foundations, and in ginseng gardens. A wettable powder
formulation is used as a foliar spray for nursery and greenhouse
ornamentals. A pressurized liquid is applied as a total release aerosol spray
in commercial greenhouses.
Although the total volume of use is relatively low, methiocarb is
considered an important tool for controlling slugs and snails in nurseries and
greenhouses.
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Regulatory
History
Human Health
Assessment
Methiocarb was first registered as a pesticide in the U.S. in 1972.
EPA issued a Registration Standard for methiocarb in March 1987 (NTIS
#PB87-190898), requiring additional product chemistry, residue chemistry,
ecological effects, environmental fate, toxicology, and occupational and
residential exposure data. The methiocarb producers deleted all food uses
from their product labels between 1989-92, so residue chemistry studies are
no longer required. The technical producer is no longer supporting the
commercial turf use of methiocarb. If end-use registrants do not support
this use, it will have to be removed from product labels.
Currently, 22 pesticide products are registered which contain the
active ingredient methiocarb. All methiocarb products for outdoor use
except products with homeowner uses are classified as Restricted Use
Pesticides, and may be applied only by or under the direct supervision of
certified applicators.
Toxicity
Methiocarb is among the carbamate family of chemicals; that is, it has
the ability to inhibit the body's production of cholinesterase, an enzyme
necessary for accurate transmission of nerve impulses.
In acute toxicity studies using laboratory animals, methiocarb has been
shown to be highly toxic by the oral route and has been placed in Toxicity
Category I (the highest of four levels) for acute oral effects. It is
moderately toxic by the inhalation route and slightly toxic by the dermal
route, and has been placed in Toxicity Categories II and III for these effects.
Methiocarb is not an eye or skin irritant, and it does not cause delayed
neurotoxicity.
Subchronic dermal toxicity studies using rabbits showed inconsistent
results, but the range-finding study resulted in treatment-related deaths at
the higher doses. In chronic feeding studies using rats and beagle dogs,
methiocarb caused inhibition of red blood cell and plasma cholinesterase,
but not brain cholinesterase. In the dog study, hind limb weakness and
tremor occurred in the high dose group. Methiocarb is not carcinogenic in
rats, and does not appear to have any mutagenicity potential. Administered
by the dermal route, methiocarb is associated with developmental toxicity in
rabbits. By the oral route, it is associated only with maternal toxicity in
both rats and rabbits.
Although they are not part of the target data base for reregistration,
acute and chronic neurotoxicity studies in rodents, now required for all
carbamate pesticides, must be performed for methiocarb.
Dietary Exposure
Dietary exposure to methiocarb is not expected to occur since there
are no remaining food uses. Ginseng is not considered a food use since
current methiocarb labels require a 12-month preharvest interval. The
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Agency will revoke all existing methiocarb tolerances (maximum food
residue limits) set forth in 40 CFR 180.320.
Occupational and Residential Exposure
Methiocarb wettable powder products applied as foliar sprays can
result in dermal and inhalation exposure to mixers, loaders and applicators.
Use of the granular and total release aerosol products is expected to result in
less applicator exposure than use of the foliar sprays.
Post-application exposure also may occur following most methiocarb
applications. Examples include dermal exposure to residues on treated
lawns, turf and soil following the granular applications, dermal exposure to
foliage of commercially grown ornamentals following the wettable powder
and pressurized liquid formulations, and inhalation exposure following
application of total release aerosol sprays.
Methiocarb meets both the toxicity and the exposure criteria requiring
mixer/loader/applicator exposure data and post-application reentry data.
These studies will be required for reregistration of the commercial use of
the wettable powder formulation to greenhouse- and nursery-grown
ornamentals.
The Worker Protection Standard (WPS) converted the previous 24-
hour worker reentry interval (where reentry with protective clothing is
allowed) to a 24-hour restricted entry interval or REI (where entry is limited
to performance of short term activities as defined in the WPS). Considering
the toxicological concerns with methiocarb, EPA considers these additional
protections essential to its decision that REIs will sufficiently mitigate risks
to workers.
Human Risk Assessment
Since no food uses are registered, methiocarb poses no human dietary
risks. Regarding acute toxicity, methiocarb is extremely toxic by the oral
route but is moderately to slightly toxic by other routes of exposure.
Methiocarb is a developmental toxicant, and workers and homeowners may
be at risk for developmental effects from exposure to methiocarb during or
after application.
For handlers of the wettable powder/foliar spray formulation of
methiocarb using currently-required personal protective equipment (PPE),
the estimated margin of exposure (MOE) for dermal and inhalation toxicity
is estimated to be less than 100, the commonly accepted margin. However,
with the use of additional PPE (coveralls), the MOE increases to well over
100. To achieve an acceptable MOE, therefore, EPA is requiring use of
additional PPE.
EPA also is concerned about workers entering treated areas following
application of methiocarb. To protect workers, the Agency is requiring a
25-day restricted entry interval (REI) following foliar applications of the
wettable powder and pressurized liquid (total release aerosol) formulations
to ornamental plants. After 10 days, workers may enter treated areas to
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Environmental
Assessment
perform tasks, including hand labor tasks that involve contact with treated
surfaces, provided each worker spends no more than 3 hours in each 24-
hour period performing such tasks. PPE is not required during the 3-hour
work period.
Because methiocarb has been identified as a developmental toxicant,
EPA is requiring use of extra PPE by all applicators, handlers and early
entry workers. These PPE requirements will not apply to homeowner users
of methiocarb since their frequency and duration of exposure is less than
that of occupationally exposed users.
Environmental Fate
Methiocarb appears to be moderately persistent and relatively
immobile in soil, and is not likely to contaminate ground water. A full
assessment will be possible only when confirmatory hydrolysis, adsorption-
desorption/leaching and terrestrial field dissipation studies are submitted.
Ecological Effects
Methiocarb is toxic to terrestrial mammals. It is very highly toxic to
birds on an acute oral basis. In subacute studies, it is slightly toxic to
waterfowl and practically non-toxic to upland game birds. Methiocarb is
highly toxic to coldwater and warmwater fish, and very highly toxic to
aquatic invertebrates. It also is very highly toxic to honey bees.
Ecological Effects Risk Assessment
Outdoor use of methiocarb is likely to have adverse effects on aquatic
and terrestrial species. For all formulations of methiocarb used on all
outdoor sites, acute and/or chronic levels of concern are exceeded for avian
and mammalian species, aquatic invertebrates and other aquatic organisms.
Although methiocarb is used in low volumes compared to other pesticides, it
still could have major impacts in areas where there is concentrated outdoor
use.
Methiocarb may pose a hazard to endangered species including many
listed birds, mammals, insects, and aquatic organisms. The U.S. Fish and
Wildlife Service will be consulted and a generic label statement may be
required when EPA's Endangered Species Program is implemented.
EPA is requiring additional use precautions and maximum application
rates on product labels, requiring additional confirmatory data, and
negotiating with the registrants to maintain a production cap in an effort to
decrease the environmental risks of methiocarb.
Additional Data
Required
EPA is requiring the following additional generic data to confirm its
risk assessment for methiocarb: estimation of dermal exposure for wettable
powder formulation use in greenhouses and nurseries; estimation of
inhalation exposure for wettable powder formulation use in greenhouses and
nurseries; inhalation passive dosimetry for pressurized liquid formulation
use in greenhouses; estimation of dermal exposure and soil dissipation for
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Product Labeling
Changes Required
granular formulations used on ornamentals; aquatic and estuarine organisms
(fish/mollusk/shrimp) for all lawn and turf uses; aquatic invertebrate life
cycle for all lawn and turf uses; fish early life stage for all lawn and turf
uses; fish life cycle for all lawn and turf uses; hydrolysis for all outdoor
uses; adsorption/desorption/leaching for all outdoor uses; terrestrial field
dissipation for all lawn and turf uses; outdoor usage data (pounds used per
year by site); foliar dislodgeable dissipation and dermal passive dosimetry
for residential lawns and turf; and acute and subchronic neurotoxicity data
(which are not part of the target data base for reregistration).
EPA is requiring product-specific data including product chemistry
and acute toxicity studies, as well as revised labeling, for reregistration of
pesticide products containing methiocarb.
All methiocarb end-use products must comply with EPA's current
pesticide product labeling requirements. In addition:
Worker Protection Standard (WPS) - Any product whose labeling permits
use in the production of an agricultural plant on any agricultural
establishment (farm, forest, nursery or greenhouse) must comply with the
labeling requirements of EPA's Worker Protection Standard (WPS). See
PR Notice 93-7, "Labeling Revisions Required by the Worker Protection
Standard (WPS)," and PR Notice 93-11, "Supplemental Guidance for PR
Notice 93-7." Unless specifically directed in the RED, all statements
required by the WPS and reflected in these two PR Notices must be
included on product labeling.
Entry Restrictions - [See the RED for detailed instructions.] For uses
within the scope of the WPS and products not primarily intended for home
use:
• Wettable Powder Formulations - A 25-day restricted entry interval (REI)
is required:
"Do not enter or allow worker entry in treated areas during the
restricted entry interval (REI) of 25 days, except, after 10 days,
workers may enter treated areas to perform tasks including hand
labor tasks that involve contact with treated surfaces provided
each worker spends no more than 3 hours in each 24 hour period
performing such tasks."
• Pressurized Liquid Formulations - A 25-day REI is required: (see
statement above).
• Granular Formulations - A 24-hour REI is required, except for products
intended primarily for home use.
Personal Protective Equipment (PPE) Requirements
[See the RED for detailed instructions.]
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• For Products Not Primarily Intended for Home Use - The minimum PPE
requirement is:
"Applicators and other handlers must wear:
—Coveralls over short-sleeved shirt and short pants
—Chemical-resistant or waterproof gloves...
—Chemical-resistant footwear plus socks
—Chemical-resistant headgear for overhead exposure
—Chemical-resistant apron when cleaning equipment, mixing, or
loading..."
In addition, handlers must wear a respirator with an organic vapor cartridge
TC-23C during early entry to greenhouses following treatment with the
pressurized liquid for those tasks associated with ventilating the greenhouse.
A dust mask must be worn while mixing/loading the wettable powder
formulation.
Compare the PPE requirements set forth in the RED to the PPE
requirements, if any, on current labeling and retain the more protective.
• For Products Intended for Home Use - Do not add any additional PPE
requirements but retain any requirements already on current product
labeling.
• For Entry During the Restricted Entry Period - See the RED for
detailed instructions.
• For Uses Not Within the Scope of the WPS, and For Products Primarily
Intended for Home Use - Do not add any new entry restrictions but retain
any on current product labeling.
Lawn and Turf Uses
• If a registrant chooses to support lawn and turf uses, he must submit the
data required in the RED.
• If a registrant chooses to support the residential lawn uses only, he must
add the following statement to his product labels to remove the site from the
scope of the WPS:
"Not for use on turf being grown for sale or other commercial
use as sod, or for commercial seed production, or for research
purposes."
• If a registrant does not support the residential lawn uses, he must delete
the use from the product label and add the following statement:
"Do not use on turfgrass around residences or dwellings."
Restricted Use Pesticide - The following statement must appear on the
labels of all end-use products for outdoor uses except products intended for
use by homeowners:
"Restricted Use Pesticide
Due to Toxicity to Fish, Birds, and Aquatic Organisms
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For retail sale to and use only by certified applicators or persons
under their direct supervision and only for those uses covered by
the certified applicator's certification."
Use Rates and Number of Applications - The following number of
applications must appear as the maximum application rate in the Directions
for Use section of the label, to decrease aquatic risks:
• 75% Wettable Powder -
"2 Ibs 75% wettable powder per 50 gallons of water applied up
to 2 times a year."
• Granular or Pelletized Bait -
"Should not be applied more than twice a year."
Fish and Wildlife Protection - The following statements must appear on
products for the following uses:
• Granular or Pelletized Bait for Snails and Slugs -
"This product is toxic to fish and very highly toxic to birds and
mammals. Do not apply directly to water, or to areas below the
mean high water mark. Runoff from treated area may be
hazardous to aquatic organisms in adjacent aquatic sites. Do not
contaminate water when disposing of equipment washwaters and
rinsates."
• 75% Wettable Powder Formulation -
"This pesticide is toxic to fish and very highly toxic to birds and
mammals. Do not apply directly to water, or to areas below the
mean high water mark. Runoff from treated area may be
hazardous to aquatic organisms in adjacent aquatic sites. Do not
contaminate water when disposing of equipment washwaters and
rinsates.
"This product is very highly toxic to honey bees exposed to
direct treatment or residues on blooming shrubs, flowers, weeds
and trees. Do not apply this product or allow it to drift to
blooming shrubs, flowers, weeds, or trees if bees are visiting the
treatment area."
Regulatory
Conclusion
The use of most currently registered pesticide products containing
methiocarb in accordance with approved labeling, except the use of granular
and pelletized formulations on residential lawns and turf, and except
products for use by homeowners on ornamentals marketed in 20-25 pound
bags, will not pose unreasonable risks or adverse effects to humans or the
environment. Therefore, uses of methiocarb on residential and commercial
ornamentals (except large size products for use by homeowners on
ornamentals), by homeowners around building foundations, in greenhouses,
on commercially grown turfgrass, and on ginseng are eligible for
reregistration.
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For More
Information
These products will be reregistered once the required confirmatory
generic data, product specific data and revised labeling are received and
accepted by EPA. Products which also contain other active ingredients will
be reregistered after the other active ingredients are determined to be
eligible for reregistration.
EPA cannot make a reregistration eligibility decision regarding the
residential lawn and turf use of methiocarb until appropriate postapplication
reentry exposure, ecological effects and environmental fate data are
submitted and evaluated.
The Agency similarly cannot make a reregistration eligibility decision
regarding large size methiocarb products for use by homeowners on
ornamentals, marketed in 20-25 pound bags, until soil dissipation and
dermal exposure data are received and evaluated.
EPA is requesting public comments on the Reregistration Eligibility
Decision (RED) document for methiocarb 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.
Following the comment period, the methiocarb RED document will be
available from the National Technical Information Service (NTIS), 5285
Port Royal Road, Springfield, VA 22161, telephone 703-487-4650.
For more information about EPA's pesticide reregistration program,
the methiocarb RED, or reregistration of individual products containing
methiocarb, please contact the Special Review and Reregistration 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, from 8:00 am to 6:00 pm Central Time, Monday
through Friday.
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