United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-95-021
September 1995
R.E.D. FACTS
Pesticide
Reregistration
Asulam
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 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 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 reregi strati on, EPA announces this
and explains why in a Reregistration Eligibility Decision (RED) document.
This fact sheet summarizes the information in the RED document for
reregi strati on case 0265, methyl sulfanilylcarbamate and sodium salt of
methyl sulfanilylcarbamate, commonly known as asulam.
Use Profile
Asulam is a selective postemergent systemic carbamate herbicide
used to control a variety of annual grasses and broadleaf weeds on
sugarcane, Christmas tree plantations, ornamentals, turf (St. Augustinegrass
and Bermudagrass) and non-cropland uses (boundary fences, fencerows,
hedgerows, lumberyards, storage areas and industrial plant sites, and
warehouse lots). Its major use site is sugarcane. The only end-use
formulation of asulam is soluble/concentrate liquid (sodium salt of asulam).
Asulam is applied by aerial or ground spray, broadcast, band, and spot
treatment.
Use practice limitations prohibit applying asulam through any type of
irrigation system; discharging into bodies of water; using treated plants for
feed or forage; and treating crops/sites within 90 days of harvest.
Regulatory Asulam was first registered as a pesticide in the U.S. in 1975. EPA
History issued a Registration Standard for Asulam in December 1987 (PB88-
168588). A 1991 Data Call-In (DCI) required additional neurotoxicity,
plant protection, animal feeding, dermal mixer/loader exposure and
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inhalation exposure data. Currently, 1 technical asulam product and 3
sodium salt of asulam products are registered.
Human Health
Assessment
Toxicity
Asulam technical is of relatively low acute toxicity. It is practically
non-toxic by the oral and inhalation routes; technical asulam is in Toxicity
Category IV (the lowest of four categories) for these effects. It is slightly
toxic by the dermal route (Toxicity Category III). It causes slight eye
irritation in rabbits (Toxicity Category III) and is not a skin sensitizer.
In a subchronic dermal study using rabbits, no treatment-related
effects were observed.
Asulam is carcinogenic in rats based on thyroid and adrenal tumors in
males. It has been classified as a Group C carcinogen — that is, a possible
human carcinogen for which there is limited animal evidence.
In a chronic toxicity study using beagle dogs, reductions in food
consumption, body weight gain, vomiting, diarrhea, and reduction in red
blood cells, increase in thyroid and kidney weights and reduced testicular
weights were noted in the high dose groups. A carcinogenic study using
mice cause increased spleen weights in males and decreased brain weights
and decreased survival in females.
In a developmental toxicity study using rats, the highest dose level
caused maternal toxic effects of decreased body weight gain and slight
increase in resorptions. In a study using rabbits, asulam caused maternal
effects of decreased body weight.
A 2-generation reproduction study showed a reduction in the number
of live births per litter, and decreases in body weight and organ weights.
Asulam is not mutagenic.
Dietary Exposure
People may be exposed to residues of asulam through the diet.
Tolerances or maximum residue limits have been established for asulam in
sugarcane (please see 40 CFR 180.360).
Residue data show that sugarcane concentrates in the processed feed
commodity, blackstrap molasses. Under the Delaney clause of the Federal
Food, Drug, and Cosmetic Act (FFDCA), EPA may be barred from
establishing a feed additive regulation (tolerance) for blackstrap molasses
because asulam may be found to be an animal carcinogen within the
meaning of the Delaney clause. The Delaney clause prohibits the
establishment of a regulation for any food/feed additive that is found to
induce cancer in man or animals. Further, under current policy, EPA would
not issue these food and feed additive tolerances, and would not continue in
effect a tolerance for the associated raw agricultural commodity, sugarcane.
The Agency has committed to revoking the underlying raw agricultural
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commodity tolerance where food/feed additive tolerances have been
established or need to be established but cannot because of Delaney. As
part of a settlement agreement in a recent lawsuit, the Agency agreed to
complete these revocations by the year 2000. During the 5 years before
final revocation, the Agency believes it is important to amend the existing
raw agricultural commodity tolerance on sugarcane to reflect new residue
data.
The Agency will also establish new meat, milk, and meat by-product
tolerances. Current residue data suggest the existing sugarcane tolerance
should be raised to 15 ppm from 0.1 ppm. However, the registrant is
submitting additional data reflecting longer pre-harvest intervals (PHIs) and
more accurate timing of applications which will likely result in a tolerance
level lower than the 15 ppm. After reviewing these data, the Agency will
establish a new sugarcane tolerance and require the registrant to petition for
new meat, milk, and meat by-product tolerances. By amending and
establishing tolerances for what may be an interim period, the Agency
believes that these actions will prevent possible overtolerance situations and
should reduce any public confusion regarding dietary risks associated with
a crop or commodity seizure.
In addition, the Agency will also review blackstrap molasses as part
of its new policy regarding implementation of Delaney that was recently
published in the Federal Register as a response to the National Food
Processors Association petition (June 14, 1995; 60 FR 31300). The Agency
will determine if blackstrap molasses is "ready-to-eat" as an animal feed. If
dilution with other feed items is necessary before animal consumption, and
subsequent dilution lowers the level of asulam in the diluted feed mixture to
the level of the raw agricultural commodity tolerance, then a processed feed
tolerance will not be necessary. Then the new sugarcane tolerance and new
meat, milk and meat by-product tolerances will not be revoked.
EPA has assessed the dietary risk posed by asulam. The chronic
dietary risk analysis assumed the higher reassessed tolerance level of 15
ppm and 100% crop treated. The Anticipated Residue Concentration
(ARC) for the overall U.S. population represents 3.85% of the Reference
Dose (RfD), or amount believed not to cause adverse effects if consumed
daily over a 70-year lifetime. The exposures for the two highest exposed
subgroups, children (1-6 years old) and non-nursing infants (<1 year old),
are 3.48 x 10"2 and 2.64 x 10"2 mg/kg body weight/day, respectively. These
exposure values represent 9.7% and 7.3% of the RfD, respectively. This
low fraction of the allowable RfD is acceptable dietary risk.
Occupational and Residential Exposure
Based on current use patterns, handlers (mixers, loaders, and
applicators) may be exposed to asulam during and after applications in
agricultural and other settings. However, there are no toxicological
endpoints of concern for short to intermediate term occupational exposure.
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Environmental
Assessment
There are no residential uses for asulam; therefore, no exposure or risk is
expected from asulam to homeowners.
The Agency is requiring that the current restricted entry interval (REI)
of 12 hours for uses within the scope of the Worker Protection Standards
(WPS) be maintained. This 12 hour REI is the minimum acceptable REI
for asulam. There are no special toxicological concerns about asulam that
warrant the establishment of active-ingredient-based minimum personal
protective equipment (PPE) requirements. The Agency is also requiring the
following early-entry PPE, which is the minimum required under the WPS:
coveralls, chemical-resistant gloves, and shoes plus socks.
Human Risk Assessment
Asulam generally is of low acute toxicity, but it is classified as a non-
quantifiable Group C carcinogen (that is, a possible human carcinogen for
which there is limited animal evidence), and shows some evidence of
developmental and reproductive toxicity. The only food crop use is
sugarcane. However, dietary exposure to asulam residues in foods is
extremely low, as is the cancer risk posed to the general population.
Application and post-application risks to workers and others are
minimal because asulam has no toxicological endpoints of concern for the
short to intermediate term occupational exposure. Post-application reentry
workers will be required to observe a 12-hour restricted entry interval
(REI). The following early-entry PPE is the minimum required under the
WPS: coveralls, chemical-resistant gloves, and shoes plus socks.
Environmental Fate
The environmental fate assessment is considered preliminary because
of contradictory data. Although there is a lack of acceptable terrestrial field
dissipation data and the Agency has concerns about the integrity of data for
key laboratory studies, based on the supplemental data, it appears that
asulam is highly mobile and has a strong potential to leach into ground
water or move offsite into surface water. Also, based on available data
(including those from unreliable studies), asulam has the following
characteristics: 1) highly to very highly soluble, 2) stable in water without
light, 3) unstable in water and on soil under light; however, small amounts
of asulam were detected in surface water, 4) relatively unstable in soil under
aerobic conditions, 5) very stable in soil and sediment under anaerobic
conditions, 6) very mobile in soil, 7) not volatile, and 8) does not
accumulate in fish.
The Agency is requiring additional storage stability data (aerobic soil
metabolism and anaerobic soil/aquatic metabolism) to validate the results of
the laboratory studies and to assess the need for the field dissipation study.
In addition, a groundwater label advisory and a surface water label advisory
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are required. Due to concerns about off-target damage by the aerial
application of asulam, spray drift data (droplet size spectrum and drift field
evaluation) and a label advisory are also required.
Ecological Effects
Technical asulam is practically nontoxic to freshwater fish and
slightly toxic to freshwater invertebrates. Also, asulam is practically
nontoxic to estuarine/marine species, honeybees, and small mammals.
Chronic effects to avian species and aquatic invertebrate cannot be fully
assessed due to lack of adequate data. However, based on the overall low
risk asulam poses to aquatic and avian species, the Agency does not expect
that asulam will pose a high chronic risk to aquatic invertebrates or avian
species. The Agency is requiring a confirmatory aquatic invertebrate life
cycle study. The Agency is not requiring avian reproduction studies due to
the extremely short photolytic half-life (approximately 2 hours) and, in
acute studies, the practically non-toxic nature of asulam to birds and
mammals.
Levels of concern from all uses of asulam have been exceeded for
endangered and non-endangered terrestrial and semi-aquatic plants. For
non-cropland uses, asulam exceeds levels of concern for endangered and
non-endangered aquatic plants. A comprehensive risk assessment for
nontarget plants cannot be determined due to the lack of adequate data.
High isk to nontarget plants is likely, based on the herbicidal properties of
asulam. The Agency is requiring additional phytotoxicity data to complete
the nontarget plants risk assessment for asulam.
Ecological Effects Risk Assessment
Asulam poses minimal risk to honeybees. Chronic risk to birds
cannot be assessed at this time due to the lack of avian reproduction data.
However, the Agency believes there is little potential for adverse effects to
avian reproduction as the available environmental fate information indicates
that photolysis in water and soil is very rapid — approximately 2 hours.
Regarding mammals, the use of asulam on noncropland at the
maximum use rate, or any other use site, is not likely to adversely affect
mammalian reproduction.
Regarding aquatic risks, acute effects are low for aquatic
invertebrates. However, chronic effects to fish and aquatic invertebrates
cannot be fully assessed without further data.
Endangered and non-endangered species levels of concern are
exceeded for terrestrial and semi-aquatic plants for all uses of asulam. For
the noncropland use of asulam, endangered and non-endangered species are
exceeded for aquatic plants. A comprehensive risk assessment cannot be
determined for nontarget plants without further data. When the Endangered
Species Program goes into effect, limitation on the use of asulam will be
required to protect endangered and threatened species.
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Risk Mitigation
Since the current uses of asulam and its sodium salt exceed ecological
effects levels of concern, EPA is requiring the following risk mitigation
measures.
° Prohibiting the aerial uses of asulam for non-cropland and Christmas trees
use sites;
° Clarifying the non-cropland use to state 1 gallon/acre rate, 1 application
per season;
° Clarifying the Christmas tree uses to state 1 application per season;
° Clarifying the turf use to state sod farms use only and 1 application per
season;
° Ground water label advisory;
° Surface water label advisory; and
° Long term ground water monitoring in and near asulam use areas.
The registrant also is required to clarify the environmental fate
assessment methodology and the uncertainty associated with the extraction
technique and recovery of asulam from the laboratory versus the field
studies.
Additional Data EPA is requiring the following additional generic studies for asulam
an<^ its sodium salt to confirm its regulatory assessments and conclusions:
Acute Aquatic Invertebrate Toxicity - Daphnia magna;
Aerobic Soil Metabolism;
Anaerobic Soil and Aquatic Metabolism;
Droplet Size Spectrum;
Drift Field Evaluation;
Directions for Use - Label amendment (lower application rate and/or
longer PHI);
Plant Metabolism Study;
Magnitude of Residue - Sugarcane; and
Confined Rotational Crop
After reviewing additional field trial data for sugarcane, the Agency
will establish a new sugarcane tolerance and require the registrant to
petition for new meat, milk and meat by-product tolerances.
Certain data are not part of the reregistration target database for
asulam, but are also required:
Seedling emergence - soybeans and radish
Vegetative vigor - cucumber and onion
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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 reregi strati on.
Product Labeling All asulam end-use products must comply with EPA's current
ChanCIGS pesticide product labeling requirements, and with the following:
Required Worker Protection
Personal Protective Equipment/Entry Restrictions; Labeling
Personal Protective Equipment (PPE) for Handlers
(Mixer/Loader/Applicators)
The PPE for mixer/loader/applicators is to be based on the acute
toxicity of the end-use product.
Entry Restrictions for Occupational-Use Products (WPS Uses)
Based on the assessment of human health risks, the Agency
does not believe an increase in the REI above what is required in the
Worker Protection Standard (WPS) is warranted. The current 12 hour
REI, pertaining to each use of the product that is within the scope of
the WPS, is to be maintained. This 12 hour REI is the minimum
acceptable REI for asulam.
Early Entry PPE: The PPE for early entry are the minimum that
would be required under the WPS. These are: coveralls, chemical-
resistant gloves, shoes, and socks.
Entry Restrictions for Occupational-Use Products (NonWPS Uses)
Some registered uses of asulam are outside the scope of the
Worker Protection Standard (WPS). For nonWPS uses the Agency is
requiring the following.
"Do not enter or allow others to enter the treated
area until sprays have dried."
Other Labeling Requirements
The Agency is requiring the following labeling statements to be
located on all end-use products containing asulam that are intended
primarily for occupational use:
Products Intended Primarily for Occupational Use
Engineering Controls Used
"When handlers use closed systems, enclosed cabs, or
aircraft in a manner that meets the requirements listed in the
Worker Protection Standard for Agricultural Pesticides (WPS)
[40 CFR 170.240(d)(4-6)], the handler PPE requirements may
be reduced or modified as specified in the WPS. However, full
PPE must be available in the event that the handler exits the
aircraft, enclosed cab, etc. prior to the REI."
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User Safety Requirements
"Follow manufacturer's instructions for cleaning/
maintaining PPE. If no such instructions for washables, use
detergent and hot water. Keep and wash PPE separately from
other laundry."
User Safety Statements
"Users must wash hands before eating, drinking, chewing
gum, using tobacco, or using the toilet."
"Users must leave the treated area, and remove clothing
immediately if pesticide gets inside."
"Users must remove PPE immediately after handling this
product. As soon as possible, wash thoroughly and change into
clean clothing. Wash the outside of gloves before removing."
Application Restrictions
"Do not apply this product in a way that will contact
workers or other persons, either directly or through drift. Only
handlers with appropriate PPE may be in the area during
application."
Homeowner-Use Products
There are no products containing asulam that provide directions
intended for homeowner use. Current labelling provides the statement,
"For agricultural or commercial use only, not for use by homeowners. "
This statement must be maintained.
Environmental Hazard
The labels of all asulam end-use products must be revised to bear the
following under the Environmental Hazard Section:
Wetland Statement
"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
wash water or rinsate."
Ground Water Advisory
"This chemical is known to leach through soil into ground
water under certain conditions as a result of agricultural use.
Use of this chemical in areas where soils are permeable,
particularly where the water table is shallow, may result in
ground-water contamination."
Surface Water Advisory
"Surface water contamination may occur in areas with
poorly draining soils and little or no buffers or in areas where
drainage systems flow directly to surface water."
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Application Restrictions
The labels of all asulam end-use products must be revised to bear the
following application restrictions under the Directions for Use Section:
For noncropland and Christmas tree uses
"Aerial application is prohibited"
For turf uses
"For sod farm use only"
Application Rates
The labels of all asulam end-use products must be revised to bear the
following application rates under the Crop Uses Section for the respective
crops:
For asulam use on noncropland sites
A maximum application rate of 1 gallon/A with use limited to single
application per year.
For asulam use on Christmas trees
A maximum application of 1 gallon/A with use limited to single
application per year.
For asulam use on turf (sod farm use only)
A maximum application of 1 gallon/A with use limited to single
application per year.
Spray Drift
The following language must be placed on each asulam product label
that can be applied aerially:
"AVOIDING SPRAY DRIFT AT THE APPLICATION SITE IS THE
RESPONSIBILITY OF THE APPLICATOR."
"The interaction of many equipment and weather-related factors
determine the potential for spray drift. The applicator is
responsible for considering all these factors when making
decisions."
"The following drift management requirements must be
followed to avoid off-target movement from aerial applications
to agricultural field crops. These requirements do not apply to
forestry applications, public health uses or to applications using
dry formulations."
1. "The distance of the outer most nozzles on the boom must
not exceed 3/4 the length of the wingspan or rotor."
2. "Nozzles must always point backward parallel with the air
stream and never be pointed downwards more than 45 degrees."
"Where states have more stringent regulations, they should be
observed."
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The applicator should be familiar with and take into account the
information covered in the Aerial Drift Reduction Advisory below.
AERIAL DRIFT REDUCTION ADVISORY
The following aerial drift reduction advisory information must be contained
in the product labeling:
[This section is advisory in nature and does not supersede the mandatory
label requirements].
Information on Droplet Size
The most effective way to reduce drift potential is to apply large droplets.
The best drift management strategy is to apply the largest droplets that
provide sufficient coverage and control. Applying larger droplets reduces
drift potential, but will not prevent drift if applications are made improperly,
or under unfavorable environmental conditions (See Wind, Temperature
and Humidity, and Temperature Inversions).
Controlling Droplet Size
o Volume - Use high flow rate nozzles to apply the highest practical
spray volume. Nozzles with higher rated flows produce larger
droplets.
o 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 flow rate
nozzles instead of increasing pressure.
o Number of nozzles - Use the minimum number of nozzles that
provide uniform coverage.
o Nozzle Orientation - Orienting nozzles so that the spray is released
parallel to the airstream produces larger droplets than other
orientations and is the recommended practice. Significant deflection
from horizontal will reduce droplet size and increase drift potential.
o Nozzle Type - Use a nozzle type that is designed for the intended
application. With most nozzle types, narrower spray angles produce
larger droplets. Consider using low- drift nozzles. Solid stream
nozzles oriented straight back produce the largest droplets and the
lowest drift.
Boom Length
For some use patterns, reducing the effective boom length to less than 3/4
of the wingspan or rotor length may further reduce drift without reducing
swath width.
Application Height
Applications should not be made at a height greater than 10 feet above the
top of the target plants unless a greater height is required for aircraft safety.
Making applications at the lowest height that is safe reduces exposure of
droplets to evaporation and wind.
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Swath Adjustment
When applications are made with a crosswind, the swath will be displaced
downwind. Therefore, on the up and downwind edges of the field, the
applicator should compensate for this displacement by adjusting the path of
the aircraft upwind. Swath adjustment distance should increase, with
increasing drift potential (higher wind, smaller drops, etc.).
Wind
Drift potential is lowest between winds speeds of 2 -10 mph. However,
many factors, including droplet size and equipment type determine drift
potential at any given speed. Application should be avoided below 2 mph
due to variable wind direction and high inversion potential. NOTE: Local
terrain can influence wind patterns. Every applicator should be familiar
with local wind patterns and how they affect spray drift.
Temperature and Humidity
When making applications in low relative humidity, set up equipment to
produce larger droplets to compensate for evaporation. Droplet evaporation
is most severe when conditions are both hot and dry.
Temperature Inversions
Applications should not occur during a temperature inversion because drift
potential is high. Temperature inversions restrict vertical air mixing, which
causes small suspended droplets to remain in a concentrated cloud. This
cloud can move in unpredictable directions due to the light variable winds
common during inversions. Temperature inversions are 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
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 vertical air mixing.
Sensitive Areas
The pesticide should only be applied when the potential for drift to adjacent
sensitive areas (e.g., residential areas, bodies of water, known habitat for
threatened or endangered species, non-target crops) is minimal (e.g, when
wind is blowing away from the sensitive areas).
Although levels of concern are exceeded for endangered and non-
ConclllSJOn endangered plant species and surfacewater and groundwater quality, the
Agency concludes that the current registered products containing asulam
and its sodium salt for all uses, with the exception of sugarcane, once
amended to reflect the risk mitigation measures imposed in this RED, are
eligible for reregi strati on. Therefore, products containing asulam and its
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sodium salt for uses on Christmas tree plantations, ornamentals, turf (St.
Augustinegrass and Bermudagrass), and non-cropland (boundary fences,
fencerows, hedgerows, lumberyards, storage areas, industrial plant sites,
and warehouse lots) are eligible for reregi strati on.
EPA is unable to make a reregi strati on eligibility decision regarding
the use of asulam and its sodium salt on sugarcane because data show that
asulam concentrates in the processed animal feed commodity, blackstrap
molasses. Under current policies, the establishment of the necessary feed
additive regulation (tolerance) to cover residues in this commodity may be
barred by the Delaney clause of Section 409 of the Federal Food, Drug, and
Cosmetic Act (FFDCA) because asulam may induce cancer in animals
within the meaning of the Delaney clause.
Asulam and its sodium salt products with eligible uses 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 Reregi strati on Eligibility
Decision (RED) document for asulam 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 asulam RED document also 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 reregi strati on program,
the asulam RED, or reregi strati on of individual products containing asulam
and its sodium salt, please contact the Special Review and Reregi strati on
Division (7508W), OPP, US EPA, Washington, DC 20460, telephone 703-
308-8000.
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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 8:00 am and 8:00 pm Eastern Standard
Time, Monday through Friday.
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