United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-96-012
July 1996
R.E.D. FACTS
Norflurazon
Pesticide
Reregistration
Use Profile
Regulatory
History
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 Reregistration Eligibility Decision (RED) document.
This fact sheet summarizes the information in the RED document for
reregi strati on case 0229, norflurazon.
Norflurazon is a selective preemergent herbicide used to control
germinating annual grasses and broadleaf weeds in fruits, vegetables, nuts,
cotton, peanuts, soybeans, and various nonagricultural and industrial areas.
Formulations include granular, flowable concentrate, and water dispersible
granules.
Norflurazon is applied using aerial application, chemigation (drip
and/or sprinkler), and soil treatment (broadcast and incorporation).
Use practice limitations prohibit applying norflurazon through any
type of irrigation system (only for the Zorial Rapid 80® product); grazing
livestock in treated areas or cut treated crops for feed; grazing or harvesting
for forage or hay; and grazing or feeding for forage.
Norflurazon was first registered as a pesticide in the U.S. in 1974.
EPA issued a Registration Standard for Norflurazon in December 1984
(PB86-135159). A June 1989 Second Round Review draft document was
completed for norflurazon and the studies required in the Second Round
Review document were eventually levied in the August 1990 Data Call-In
(DCI). EPA issued subsequent DCIs in January and June 1993, requiring
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additional data on groundwater monitoring and estuarine studies. Currently,
eight norflurazon products are registered.
Human Health
Assessment
Toxicity
In studies using laboratory animals, norflurazon generally has been
shown to be of low acute toxicity. It is practically nontoxic by the oral and
dermal routes, as well as in terms of eye and dermal irritation in rabbits. It
has been placed in Toxicity Category IV (the lowest of four categories) for
these effects. Studies on acute inhalation and dermal sensitization are
required.
A subchronic toxicity study using rats resulted in changes in blood
cell counts, increases in liver and thyroid weights, a decrease in enzyme
activity, and an increase in thyroid effects at the highest dose level. In a
subchronic study using rabbits, increases in enzyme activity, liver weight,
and liver to body weight ratio in both sexes, and a slight redness of the skin
were observed at the highest dose level.
In a chronic toxicity study using beagle dogs, liver weight increases,
thyroid weight changes, increased cholesterol levels, and a decrease in red
blood cell counts were noted in the high dose groups. A nine-month oral
toxicity study using rats resulted in liver weight increases, an increase in the
incidence of tubular degeneration, and changes in the thyroid weight.
In a 2-year carcinogenicity study using mice, increases in liver weight
and liver to body weight ratio were observed. Also, increased incidences of
enlarged spleen, nephritis, swollen/enlarged liver, and nodular enlargement
of the liver were observed in male mice at the highest dose level, while
increased incidences of an inflamed kidney (inflammation of kidney and its
pelvis), enlarged liver, and cystic ovaries were observed in female mice at
the highest dose level.
A chronic toxicity and carcinogenicity study using rats resulted in
increases in liver weight in males and females, kidney weight increases in
both sexes, and thyroid weight increases in males. Also, kidney effects
were observed in the high dose males. Norflurazon was classified as a non-
quantifiable "Group C" or possible human carcinogen.
A developmental toxicity study using rats caused skeletal
abnormalities which were not statistically significant and are believed to be
secondary to maternal effects at the high dose level. In a study using
rabbits, norflurazon caused maternal effects of decreased body weight and
clinical toxicity and developmental toxicity in the form of decreased mean
fetal weight and skeletal abnormalities.
A one-generation reproductive toxicity study using mice showed no
treatment-related effects at any dose levels. A 2-generation reproductive
toxicity study in rats caused increased pup death, increased stillborn pups,
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and increased pup deaths between days 5-14 of lactation at the highest dose
level. Norflurazon is not considered to be mutagenic.
Dietary Exposure
People may be exposed to residues of norflurazon through the diet.
Tolerances or maximum residue limits have been established for
norflurazon in many fruits, vegetables, and nuts, and in cotton, peanuts, and
soybean commodities (please see 40 CFR §180.356). EPA has reassessed
the norflurazon tolerances and found that sufficient data are available to
support the established tolerances for almonds, apples, apricots, asparagus,
avocados, blackberries, blueberries, cherries, citrus, cottonseed, cranberries,
filberts, grapes, hops, nectarines, peaches, peanuts, pears, pecans, plums,
raspberries, soybeans, soybean forage and hay, walnuts, milk, and the fat,
meat, and meat-by-products of cattle, hogs, horses, and sheep.
The tolerance for hops, green under 40 CFR §180.356 must be
revoked and a tolerance for the raw agricultural commodity hops, green and
dried must be established under tolerances with regional registrations (40
CFR §180.356(x)). Tolerances for citrus molasses and dried citrus pulp
must be revoked because citrus molasses is no longer considered a
significant animal feed item and norflurazon does not concentrate in dried
citrus pulp. The tolerance for poultry, fat, meat, and meat by-products
must be revoked. A new tolerance must be established for caneberries.
Existing tolerances for blackberries and raspberries must be revoked once
the tolerance for caneberries (which encompasses both) is established.
Additional data are required for cotton gin by-products. A food additive
tolerance or Maximum Residue Limit (MRL) must be proposed for citrus
oil. Several other tolerance revisions have been proposed.
The Agency is currently reviewing additional residue data required to
upgrade the existing norflurazon metabolism studies on peanuts, cotton, and
citrus. While the submitted storage stability data indicate that residues of
norflurazon and its desmethyl metabolite are stable in plant commodities,
the registrant is required to submit radiovalidation data for the animal
method. Extended field trials for field rotational crops must be submitted
by March 1998.
EPA has assessed the dietary risk posed by norflurazon. For the overall
U.S. population and 22 subgroups, exposure from all current norflurazon
tolerances represents 10% of the Reference Dose (RfD), or amount believed
not to cause adverse effects if consumed daily over a 70-year lifetime. The
exposure level of the most highly exposed subgroup, non-nursing infants
(<1 year old), represents 47% of the RfD. Therefore, it appears that chronic
dietary risk is minimal.
The Agency does not have a concern for acute dietary exposure to
norflurazon because the margins of exposure (MOE) is 5,000 for females
of child-bearing age. An MOE of 100 or greater is considered acceptable.
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Occupational and Residential Exposure
Based on current use patterns, handlers (mixers, loaders, and
applicators) may be exposed to norflurazon during methods of application
for which no data are currently available (e.g., ring drench use), or for
which there are few data or data of less acceptable quality (e.g., ground
application using granular drop-type spreaders; aerial application of
granulars or liquids; application of dry flowable formulation using rights-
of-way equipment, backpack sprayer, and low-pressure handwand sprayer;
and flagger exposure to granulars). The calculations of potential daily
dermal dose of norflurazon received by handlers are used to assess the risk
to those handlers. It should be noted that relative to dermal exposures, the
estimated inhalation exposures for norflurazon are considered insignificant.
The MOEs for short and intermediate-term occupational exposure
subchronic systemic effects to norflurazon are greater than 100 for the
exposure scenarios considered. There are no exposure data for the ring-
drench application method. However, current information indicate that
ring-drench handlers would likely receive less exposure than from rights-of-
way handlers using a hose or cannon on a truck. Since exposures to
handlers for the rights-of-way use of norflurazon has been calculated to
yield a MOE greater than 100, the Agency expects handler exposure for the
ring-drench use to also exceed 100. However, the Agency will require that
chemical-resistant gloves be worn by ring-drench handlers, due to the lack
of exposure data and the fact that chemical-resistant gloves are required for
the other mixer/loader/applicator scenarios. Therefore, handler exposure
studies are not required for norflurazon at this time.
The Agency concludes that risks from post-application exposures to
norflurazon would be acceptable, provided entry does not occur
immediately following application. Therefore, post-application exposure
studies are not required at this time for norflurazon.
The Agency is requiring a Restricted Entry Interval (REI) of 12 hours
set by the Worker Protection Standards (WPS). If the registrant petitions
for a shorter REI, chemical specific post-application exposure data would
be required. The Agency is requiring minimum personal protective
equipment (PPE) for pesticide handlers. In addition, chemical resistant
gloves are required for mixers/loaders and applicators using handheld
equipment, such as handwands, hoses, or nozzles. Also, the Agency is
requiring the following personal protective equipment for workers who
enter the treated area before the REI has expired: coveralls, chemical
resistant gloves, and shoes plus socks.
Human Risk Assessment
Norflurazon generally is of low acute toxicity, but causes
developmental and reproductive effects in animal studies and has been
classified as a non-quantifiable Group C, possible human carcinogen. The
registered food crop uses include fruits, vegetables, and nuts. However,
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Environmental
Assessment
dietary exposure to norflurazon residues in foods is extremely low, as is the
cancer risk posed to the general population.
There is minimal concern for the risk posed to norflurazon handlers
(mixers/loaders/applicators). Exposure and risk to workers will be
mitigated by the use of PPE required by the WPS, supplemented by early
entry PPE as required by the RED. Postapplication reentry workers will be
required to observe a 12-hour Restricted Entry Interval. This is the
minimum REI required for norflurazon.
Environmental Fate
The environmental fate of norflurazon is fairly well understood.
Several environmental fate data requirements (batch equilibrium, spray
drift, and groundwater monitoring studies) remain outstanding.
Norflurazon is a persistent and mobile compound. Norflurazon's primary
route of dissipation appears to be photodegradation in water and on soil to
desmethyl norflurazon with a half-life of 2-3 days and 12-15 days,
respectively. Norflurazon is stable to hydrolysis and degrades slowly in
aerobic soil with a half-life of 130 days. In an aerobic aquatic study,
norflurazon degraded to desmethyl norflurazon with a half-life of 6-8
months. Under anaerobic conditions, norflurazon is persistent with a half-
life of approximately 8 months. The degradate, desmethyl norflurazon, is
also persistent under aerobic and anaerobic conditions.
Norflurazon is mobile to highly mobile in soil. The mobility of
desmethyl norflurazon, in soils other than high organic peat, has not been
adequately defined. Because desmethyl norflurazon is a major degradate of
norflurazon and is persistent, a new batch equilibrium study with pure
desmethyl norflurazon is required. Fish accumulation data have shown that
norflurazon has a low potential to bioaccumulate in bluegill sunfish.
There is a concern that norflurazon may contaminate surface water at
application via spray drift and runoff. Substantial amounts of applied
norflurazon could be available for runoff several months postapplication.
The Agency is not requiring any surface water monitoring studies at this
time; however, due to the mobility and persistence of norflurazon and
desmethyl norflurazon, a surface water label advisory is required. Due to
the phytotoxic nature of norflurazon and its method of application, spray
drift studies are also required.
Norflurazon is not currently regulated under the Safe Drinking Water
Act (SDWA). Therefore no MCL has been established and water supply
systems are not required to sample and analyze for it. Although, EPA's
Office of Drinking Water has not developed health advisory levels (HALs)
for norflurazon, OPP has determined an estimated HAL of 30 ppb for
comparison with levels potentially found in ground water.
Norflurazon exhibits some of the properties and characteristics of
chemicals that have been detected in groundwater. Data suggest that
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norflurazon leaches to groundwater as a result of normal agricultural use.
The Agency is concerned about the impact of norflurazon on groundwater
quality. In addition, norflurazon has been detected in several wells in
Florida at levels that approach or exceed the estimated Health Advisory
Level (HAL) of 30 ppb. Sandoz, is currently performing groundwater
monitoring studies for the Agency and the state of Florida, to better
evaluate the leaching potential of norflurazon.
Ecological Effects
Norflurazon is practically nontoxic to avian species on an acute oral
and subacute dietary basis but causes reproductive effects in birds.
Norflurazon is also practically nontoxic to mammals and insects
(honeybees).
In acute oral toxicity studies, norflurazon is moderately to slightly
toxic to both cold and warm water fish. In a fish early life stage study,
norflurazon caused chronic effects to fish at levels as low as 1.5 ppm. In an
aquatic invertebrate study, norflurazon was slightly toxic. It may cause
chronic effects on aquatic invertebrate survival and offspring production.
Norflurazon is slightly to moderately toxic to estuarine/marine organisms.
Norflurazon may cause detrimental effects to certain terrestrial plants.
It is also highly toxic to aquatic plants. The Agency is requiring further
testing to fully assess the toxicity of norflurazon to nontarget aquatic plant
species.
Ecological Effects Risk Assessment
Norflurazon may cause chronic risk to both endangered and
nonendangered avian species for some crops. It may also cause adverse
effects to small endangered mammals. Norflurazon poses minimal risk to
honeybees. Regarding aquatic risks, no acute or chronic levels of concern
have been exceeded for freshwater fish, aquatic invertebrates, and
estuarine/marine organisms.
Although further data on the toxicity of norflurazon to nontarget
aquatic plants is needed, a plant risk assessment indicates high risk and
endangered plant levels of concern are exceeded for terrestrial, semi-
aquatic, and aquatic plants.
Levels of concern are exceeded for chronic risk to avian species and
mammalian endangered species. A high risk is posed to endangered
terrestrial, semi-aquatic and aquatic plants. In order to complete the risk
assessment to nontarget aquatic plants, additional data are required for the
following species: Skeletonema costatum, Anabaenaflos-aquae, and a
freshwater diatom
Risk Mitigation The Agency has determined that the current uses of norflurazon
exceed levels of concern for chronic risk to avian species and mammalian
endangered species, and pose a high risk to endangered terrestrial, semi-
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aquatic, and aquatic plants. There is a concern that norflurazon may
contaminate ground water, as well as surface water. Norflurazon also
poses a potential risk of dermal exposure to pesticide handlers.
The registrant has already implemented several risk mitigation
measures (such as reduced application rates, use precaution statements, and
a ground water label advisory) to decrease the risks posed by norflurazon.
The registrant has agreed to further mitigate the chronic risks to birds and
mammals by: 1) clarifying the current soil incorporation statements on the
product labels, as well as, adding the statement to the use directions for
each crop; and 2) clarifying the use directions for banded treatments. A
ground water label advisory is being required on all product labels. This
advisory will reduce the potential of norflurazon contaminating ground
water. In addition, ground water monitoring studies are being conducted by
the registrant to estimate the exposure of norflurazon to the public, as well
as, to determine the persistence of residues reaching ground water. These
ground water monitoring studies will determine if additional risk mitigation
measures are needed. Likewise, a surface water advisory is being required
to decrease the risk of norflurazon contaminating surface water via spray
drift and runoff. Furthermore, the Agency is requiring a spray drift
advisory to mitigate the risks to nontarget plants by reducing the potential
drift. In addition, spray drift studies are being required to evaluate the
exposure and risk to nontarget plants. Finally, in order to decrease the
dermal risk to pesticide handlers, the Agency is requiring minimum PPE,
which include long-sleeved shirt and long pants, and shoes plus socks. In
addition, chemical-resistant gloves are required for mixers/loaders and
applicators using hand-held equipment. And a 12-hour REI is being
required to further mitigate the risk to workers and handlers. These risk
mitigation measures, along with the ones already implemented by the
registrant, should reduce the risks of norflurazon to humans and the
environment.
Additional Data EPA is requiring the following additional generic studies for
Required norflurazon to confirm its regulatory assessments and conclusions:
Product Chemistry;
Acute Inhalation for Technical and 78.6% DF;
Dermal Sensitization;
Gene Mutation (Ames Salmonella);
Directions for Use - Label Amendment to include PHIs;
Residue Analytical Methods - Animal (Radiovalidation data);
Cropfield Trials - Cotton Gin By-products;
Field Rotational Crops (in progress);
Tier II Aquatic Plant Growth;
Batch Equilibrium Study (Degradate);
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Spray Drift;
Small Scale Ground Water Monitoring (in progress);
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 norflurazon end-use products must comply with EPA's current
Changes pesticide product labeling requirements and with the following. For a
Red ui red comprehensive list of labeling requirements, please see the norflurazon
RED document.
Worker Protection
Personal Protective Equipment/Entry Restrictions; Labeling
PPE Requirements for Pesticide Handlers
The PPE for handlers is to be based on the acute toxicity of the
end-use product. The minimum PPE requirements for handlers
include long-sleeved shirt and long pants, shoes plus socks, and
chemical-resistant gloves.
Entry Restrictions - Products Intended Primarily for Occupational Use
(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. The 12-hour REI is the minimum REI
for norflurazon.
Early Entry PPE: The PPE for early entry are the minimum that
would be required under the WPS. These are: coveralls, chemical-
resistant gloves, and shoes plus socks.
Entry Restrictions - Products Intended Primarily for Occupational Use
(NonWPS Uses;)
Some registered uses of norflurazon are outside of the scope of
the Worker Protection Standard (WPS). For nonWPS uses, the
Agency is requiring the following:
For liquid applications:
"Do not enter or allow others to enter the treated area until
sprays have dried."
For granular applications:
"Do not enter or allow others to enter the treated area until dusts
have settled. In addition, if the granules are watered-in, do not
enter or allow others to enter until the treated area is dry,
following the watering-in."
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Other Labeling Requirements
Products Intended Primarily for Occupational Use
The Agency is requiring the following labeling statements to be
located on all end-use products containing norflurazon that are intended
primarily for occupational use.
Application restrictions
"Do not apply this product in a way that will contact workers or
other persons, either directly or through drift. Only protected
handlers may be in the area during application."
Engineering controls
"When handlers use closed systems, enclosed cabs, or aircraft in
a manner that meets the requirements listed in the Worker
Protection Standard (WPS) for agricultural pesticides (40 CFR
170.240(d)(4-6)), the handler PPE requirements may be reduced
or modified as specified in the WPS."
User safety requirements
"Follow manufacturers' 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 recommendations
• "Users should wash hands before eating, drinking, chewing
gum, using tobacco, or using the toilet."
• "Users should remove clothing immediately if pesticide gets
inside. Then wash thoroughly and put on clean clothing."
• "Users should remove PPE immediately after handling this product.
Wash the outside of gloves before removing. As soon as possible,
wash thoroughly and change into clean clothing."
Optional soil incorporation statement
"Exception: if the product is soil-injected, soil-incorporated or
watered-in, the Worker Protection Standard, under certain
circumstances, allows workers to enter the treated area if there
will be no contact with anything that has been treated."
End-Use Labeling
Soil Incorporation
The following soil incorporation label statement must be added
to the specific use directions for each crop on the Solicam DF®
product label:
"Solicam must be moved into the weed seed germination
zone to be effective. If no rainfall occurs within 4 weeks
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after application, the product must be incorporated by
flood or sprinkler irrigation."
The following soil incorporation label statement must be added
to the specific use directions for each crop on the Zorial Rapid 80®
product label:
"Zorial Rapid 80 must be applied and incorporated
by tillage, irrigation or rainfall before weeds
germinate."
Banded Treatments
The following label statement must be added in the
"Application Equipment" section of the norflurazon Solicam DF®
and Zorial® product labels to clarify the formulas for the row
(banded) treatment calculation:
"The solution should be mixed to the maximum
label rate and at no point on the field should the
solution be applied at a concentration any lower or
higher than the maximum label rate."
Environmental Hazard Statements
The following labeling statements must be added to "Environmental
Hazards" section of all norflurazon end-use product labels:
Labeling for Wetlands
"Do not contaminate water when disposing of equipment
washwaters. 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 allow this material to drift onto
neighboring crops or noncrop areas or use in a manner or at a
time other than in accordance with label directions because
animal, plant or crop injury, illegal residues or other undesirable
results may occur."
Labeling for Surface Water
"Norflurazon can contaminate surface water through spray drift.
Under some conditions, norflurazon may also have a high potential
for runoff into surface water (primarily via dissolution in runoff
water), for several months post-application. These include poorly
draining or wet soils with readily visible slopes toward adjacent
surface waters, frequently flooded areas, areas over-laying extremely
shallow ground water, areas with in-field canals or ditches that drain
to surface water, areas not separated from adjacent surface waters
with vegetated filter strips, and areas over-laying tile drainage systems
that drain to surface water."
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Labeling for Ground Water
"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."
Spray Drift Labeling
The following language must be placed on each 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 drift 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."
l.'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."
The applicator should be familiar with and take into account the
information covered in the Aerial Drift Reduction Advisory Information.
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).
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Controlling Droplet Size
• Volume - Use high flow rate nozzles to apply the highest
practical spray volume. Nozzles with higher rated flows
produce larger droplets.
• 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.
• Number of Nozzles - Use the minimum number of nozzles
that provide uniform coverage.
• 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.
• 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 largest 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.
Swath Adjustment
When applications are made with a crosswind, the swath will be
displaced downward. Therefore, on the up and downwind
edges of the field, the applicator must 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 wind speeds of 3-10 mph.
However, many factors, including droplet size and equipment
type determine drift potential at any given speed. Application
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should be avoided below 3 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).
Based on the risks assessments in the RED, several risks concerns
Conclusion were identified. There is the potential risk of dermal toxicity to pesticide
handlers. There is also a concern for norflurazon contaminating ground
water and surface water. And the levels of concern are exceeded for
chronic avian species, endangered mammals, and terrestrial, semi-aquatic
and aquatic plants (high risk to endangered species). Although these risks
exist, the Agency concludes that all uses of products containing
norflurazon, once amended to reflect the risk mitigation measures imposed
in this RED, are eligible for reregi strati on.
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Norflurazon 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 EPA is requesting public comments on the Reregi strati on
Information Eligibility Decision (RED) document for norflurazon 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 norflurazon 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 norflurazon RED, or reregi strati on of individual products containing
norflurazon, 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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