United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(75O8C)
EPA-738-F-O4-OO1
September 2OO3
R.E.D. FACTS
Pesticide
Reregistration
Use Profile
Regulatory
History
Sodium Acifluorfen
(Blazer®)
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 (FQPA) 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 current human health
and safety standards 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 2605,
sodium acifluorfen.
Sodium acifluorfen is an herbicide for post-emergent weed control on
agricultural crops and for residential spot treatment. Formulations include liquid,
ready-to-use and soluble concentrate. Sodium acifluorfen is sometimes
formulated or packaged with other herbicides, such as bentazon, imazaquin,
sethoxydim, or glyphosate. Sodium acifluorfen is applied by aircraft, boom
sprayer, and other ground equipment, and by hand held sprayer and trigger bottle.
Sodium acifluorfen was first registered as a pesticide in the U.S. in 1980.
There is no Registration Standard for sodium acifluorfen, but EPA issued three
Data Call-Ins (DCIs) in June 1991, March 1995, and October 1995. Currently,
12 sodium acifluorfen products are registered, only one of which is registered for
use in residential settings. The residential use product is labeled for application
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Human Health
Assessment
by spot treatment only. Because this product is packaged in a ready-to-use spray
trigger bottle, broadcast treatment is not expected to occur.
Toxicity
Sodium acifluorfen generally has been shown to have low acute oral and
dermal toxicity and practically no inhalation toxicity. It is a severe eye irritant
and moderate skin irritant but is not a skin sensitizer. Toxicity Categories, which
range from I (most toxic) to IV (least toxic), were Category I for acute eye
irritation, Category n for skin irritation, Category III for acute oral and dermal
toxicity, and Category IV for acute inhalation toxicity for sodium acifluorfen.
Toxicology studies in animals showed kidney effects following exposure to
sodium acifluorfen. Because a rat developmental toxicity study showed fetal
effects, the 10X FQPA Safety Factor was retained to account for special
sensitivity to developing organisms. A confirmatory developmental neurotoxicity
study is being required to provide additional information about susceptibility of
developing organisms.
Sodium acifluorfen is associated with tumors in rodent studies, but is not
genotoxic. In light of new information on the mechanism of tumor formation,
EPA recently classified sodium acifluorfen as "likely to be carcinogenic to
humans at high enough doses to cause the biochemical and histopathological
changes in livers of rodents but unlikely to be carcinogenic at doses below those
causing these changes." In other words, sodium acifluorfen is carcinogenic, but
only above a certain threshold, at high doses.
Dietary Exposure and Risk
People may be exposed to residues of sodium acifluorfen through food or
drinking water. EPA has assessed the dietary risk posed by sodium acifluorfen
and found that dietary risk from food and drinking water is below the Agency's
level of concern.
Acute and chronic dietary (food) risks are substantially less than 100% of
the acute and chronic Population Adjusted Dose (aPAD and cPAD, respectively)
for the general U.S. population and all population subgroups. This assessment
incorporates the 10X FQPA Safety Factor to account for special sensitivity to
infants and children. Because the chronic dietary risk assessment for non-cancer
effects is also protective in terms of cancer effects, the chronic dietary risk from
cancer is also below the Agency's level of concern.
People may also be exposed to acifluorfen, a degradate of sodium
acifluorfen, in drinking water. Because acifluorfen can also be derived from the
herbicide lactofen, the Agency conducted an aggregate drinking water assessment
that includes acifluorfen from both sodium acifluorfen and lactofen.
EPA estimated drinking water concentrations of total acifluorfen in surface
water and ground water using models. Estimated drinking water concentrations
for acifluorfen in both surface and groundwater were all below the corresponding
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drinking water level of concern (DWLOC), the maximum concentration of
acifluorfen in water that does not exceed EPA's risk concern.
Residential Exposure and Risk
Homeowners or residential handlers can be exposed to sodium acifluorfen
by applying it as a spot treatment, or by entering or performing other activities in
treated areas. Residential handlers include homeowner applicators performing
spot treatment of weeds along driveways, sidewalks, patios, and trees.
For the homeowner use of sodium acifluorfen, EPA is concerned about any
Margin of Exposure (MOE) less than 1000, which incorporates the FQPA safely
factor to protect females age 13-50 years (childbearing age) and any unborn
children. For the only potential exposure scenario, spot treatment with a ready-
to-use trigger sprayer, EPA estimated an MOE of 18000, a safety margin large
enough so that residential applicator risk is not of concern to the Agency.
Furthermore, EPA has no concerns for post-application residential exposure
because residential uses are limited to spot treatments, which do not include
broadcast application to lawns; therefore, post-application exposure is expected to
be negligible.
Occupational Exposure and Risk
Based on current use patterns, agricultural handlers (mixers, loaders, and
applicators) may be exposed to sodium acifluorfen during and after normal use of
liquid formulations in agricultural settings. EPA assessed occupational exposure
to sodium acifluorfen using data from the Pesticide Handler Exposure Database
(PHED) and proprietary data, including chemical-specific data submitted by the
technical registrant for sodium acifluorfen. Occupational exposure to sodium
acifluorfen is not of concern to the Agency for handlers using personal protective
equipment (PPE) specified on the current labels. Post application exposures to
agricultural workers re-entering treated areas for activities such as scouting, hand
weeding, and irrigating is not of concern with the current restricted entry interval
(REI) of 48 hours.
FQPA Considerations
FQPA requires that the Agency consider the available information on the
special sensitivity of infants and children, as well as the aggregate exposure from
food, drinking water, and residential use. The 10X FQPA Safely Factor was
retained for sodium acifluorfen to account for potential sensitivity of females age
13-50 years (childbearing age) and any unborn children. For sodium acifluorfen,
EPA has determined that the FQPA Safely Factor only applies to this population.
An aggregate assessment was conducted to assess combined exposures from
food, residential uses, and drinking water. Results of this aggregate assessment
indicate that the human health risks from these combined exposures are not of
concern; that is, combined risks from all exposures to sodium acifluorfen,
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including acifluorfen derived from lactofen, fit within the individual pesticide's
risk cup.
FQPA also requires the Agency to consider the "available information"
concerning the cumulative effects of a particular pesticide's residues and "other
substances that have a common mechanism of toxicity." The Agency does not
have sufficient information at this time concerning common mechanism issues to
determine whether or not sodium acifluorfen shares a common mechanism of
toxicity with other substances, including other diphenyl ethers. Therefore, for the
purposes of this risk assessment, the Agency has assumed that sodium acifluorfen
does not share a common mechanism of toxicity with any other chemicals.
Sodium acifluorfen's primary environmental degradate is the acifluorfen
anion, which is also a degradate of another herbicide, lactofen. Because lactofen
will degrade to acifluorfen in the environment, the reregistration eligibility
decision (RED) for sodium acifluorfen and the tolerance reassessment decision
(TRED) for lactofen include assessments aggregating the potential exposure to
acifluorfen from the use of both pesticides. This was done in addition to EPA's
evaluation of the combined risk from dietary exposure to residues of sodium
acifluorfen in food and water and residues resulting from residential use. EPA
does not have a risk concern for total aggregate exposure to sodium acifluorfen
residues from non-occupational exposure pathways. Therefore, EPA has
determined that risk from exposure to sodium acifluorfen is within its own "risk
cup." More detailed information can be found in the technical supporting
documents for sodium acifluorfen referenced in the RED document.
Tolerance Reassessment
The tolerances for sodium acifluorfen meet the FQPA safety standards for
the US population and sensitive populations, including infants and children.
Therefore, EPA has reassessed the sodium acifluorfen tolerances and found that 1
tolerance should be increased and 3 tolerances remain the same. The Agency is
not able to reassess the tolerance for strawberries until additional confirmatory
data are submitted and reviewed. EPA has previously revoked 15 tolerances for
livestock commodities because sodium acifluorfen does not concentrate in
livestock tissues under the current conditions of use. Also, the current tolerance
expression is appropriate and will not change. Because there are no maximum
residue limits (MRLs) for sodium acifluorfen, there are no issues of compatibility
of US tolerances with Codex MRLs.
Environmental Environmental Fate
AsSGSSrnGnt Sodium acifluorfen is persistent on soils and in aquatic environments and is
relatively mobile. It is stable to hydrolysis and does not break down in sunlight.
Off-target transport is expected to occur initially through drift and leaching, and
later through erosion and runoff. Sodium acifluorfen exists in the anion
(negatively charged) form in most agricultural soils. Several factors, including
soil pH, soil organic carbon content, and soil iron content determine the extent to
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which acifluorfen adsorbs to soil particles. Therefore, the persistence and
mobility of acifluorfen vary with different soil conditions. Because acifluorfen's
fate properties showed that it might leach to groundwater, EPA required a small
scale prospective ground water monitoring study, which was conducted on
soybeans in the central sands of Wisconsin. Acifluorfen and two degradates were
monitored; the parent only was detected at concentrations ranging from 1 to 46
ppb (average 7.33 ppb) in 56 out of 283 samples. However, a prospective
groundwater study for the related herbicide lactofen showed no detections of
acifluorfen.
Ecological Toxicity
Sodium acifluorfen is slightly toxic to fish and aquatic invertebrates and
slightly toxic to aquatic plants. It is moderately to practically nontoxic to birds on
an acute oral basis. Sodium acifluorfen is associated with reproductive effects in
bobwhite quail but not in mallard ducks. Although no data are available on the
toxicity of sodium acifluorfen to wild mammals, it is slightly toxic to rats in
laboratory studies. No effects were seen in a rat reproductive toxicity study, but
effects were seen in a rat developmental toxicity study.
There are no available data on the toxicity of sodium acifluorfen to
honeybees; therefore, a honeybee acute toxicity study is required. Limited
information is available about the toxicity of sodium acifluorfen to non-target
terrestrial plants. However, because of the potential for adverse effects from
spray drift, EPA is requiring several label amendments to limit the potential for
drift. In addition, the EPA is requiring confirmatory plant toxicity data.
Sodium acifluorfen belongs to a class of compounds known to have a
phototropic mode of action in plants and animals. To address the potential for
increased toxicity in the presence of light, a confirmatory phototoxicity study is
required for sodium acifluorfen.
Risks to Terrestrial and Aquatic Organisms
The Agency conducted a screening level ecological risk assessment to
determine the potential impact of sodium acifluorfen use on non-target terrestrial
and aquatic organisms. The Agency used modeling to evaluate ecological risks
for sodium acifluorfen.
The Agency has minor concerns for chronic risk to birds that feed on short
grasses with RQs slightly exceeding the Agency's level of concern. In a refined
assessment, which uses mean residues, RQs range from 0.15 to 1.8, which
slightly exceed the level of concern of 1.0.
The Agency has no concerns for the impacts of sodium acifluorfen on
mammalian species. In a worst case acute scenario, the acute RQ is less than
0.01 and not of concern. The chronic RQ for mammals is less than 0.05, which
does not exceed the Agency's level of concern for any registered use.
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The Agency has no concerns for the impacts of sodium acifluorfen on
aquatic organisms. The risk assessment shows that the RQs for all aquatic
species are less than 0.01, which is well below any of EPA's levels of concern.
The Agency's review of sodium acifluorfen resulted in a determination that
sodium acifluorfen will have "no effect" on threatened and endangered aquatic
organisms, mammals, and birds. Although chronic RQs for birds which eat short
grass exceed the level of concern, the only listed endangered species that
consumes short grass is the Hawaiian goose, which resides on golf courses in
Hawaii. Because sodium acifluorfen is not used in or around this bird's habitat,
the Agency concludes that there is "no effect" to endangered birds.
Risk Mitigation To lessen the risks posed by sodium acifluorfen, EPA is requiring the
following risk mitigation measures:
Dietary Risk
• An approved labeled use for strawberries and use directions are
required, to maintain the tolerance on strawberries (OPPTS
860.1200).
A 100-day plant-back interval is necessary for all rotated crops
except small grains, which require a 40-day plant-back interval.
Groundwater label advisory must be maintained on all labels.
• Confirmatory data are required, including a developmental
neurotoxicity study and determination of a lower level of
quantification (LOQ) for the analytical method.
Residential Risk
• No label changes are necessary.
Occupational Risk
No label changes are necessary.
PPE can be reduced to baseline with chemical-resistant gloves for
technical sodium acifluorfen. Additional PPE may be required on a
product-specific basis.
Ecological Risk
Label amendments to minimize the potential for spray drift are
required.
Confirmatory data are required, including Aquatic Phototoxicity
(modified fish early life stage), Honey Bee Acute Contact,
Vegetative Vigor, and Seedling Emergence studies.
Additional Data EPA is requiring the following additional generic studies for sodium
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Required acifluorfen to confirm its regulatory assessments and conclusions:
UV/visible Absorption (OPPTS 830.7050)
Fish Early Life Stage Toxicity Study (OPPTS 850.1400), modified
for Aquatic Phototoxicity
Honey Bee Acute Contact Study (OPPTS 850.3020)
Directions for Use (on strawberries) (OPPTS 860.1200)
Developmental Neurotoxicity Study in Rats (OPPTS 870.6300)
The Agency is also requiring data gaps from previous data call ins be
fulfilled. These studies must be submitted to EPA in a timely manner. These
include the following data gaps:
Analytical Methods - Plants (OPPTS Guideline 885.2300) for rice
straw, to include a lower LOQ.
Seed Germination/Seedling Emergence (OPPTS 850.4100)
Vegetative Vigor (OPPTS 850.4150)
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 reregistration.
Product Labeling All sodium acifluorfen end-use products must comply with EPA's current
Changes Required pesticide product labeling requirements and with the following:
An approved labeled use for strawberries and use directions are
required, to maintain the tolerance on strawberries (OPPTS
860.1200).
A 100-day plant-back interval is necessary for all rotated crops
except small grains, which require a 40-day plant-back interval.
Groundwater label advisory must be maintained on all labels.
Label amendments to minimize the potential for spray drift are
required.
PPE can be reduced to baseline with chemical-resistant gloves for
technical sodium acifluorfen.
For a comprehensive list of labeling requirements, please see Chapter V of the
Sodium Acifluorfen RED document.
Regulatory
Conclusion
The use of currently registered products containing sodium acifluorfen 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. These products will be reregistered once the required
confirmatory generic data, product specific data, CSFs, and revised labeling are
received and accepted by EPA. Products which contain active ingredients in
addition to sodium acifluorfen will be reregistered when all of their other active
ingredients also are eligible for reregistration.
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For More EPA is requesting public comments on the Reregistration Eligibility
Information Decision (RED) document for sodium acifluorfen during a 30-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 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 or http://www. gov/edockets.
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 Sodium Acifluorfen 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
Sodium Acifluorfen RED, or reregistration of individual products containing
sodium acifluorfen, 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
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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