United States
Environmental Protection
Prevention. Pesticides
And Toxic Substances
EPA-738-F-94-012
September 1994
&ERA R.E.D. FACTS
Pesticide
Reregistration
Use Profile
Regulatory
History
Oryzalin
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 reregistration case
0186, oryzalin.
Oryzalin is a herbicide that acts by inhibiting cell division in plants. It
is used to control annual grasses, broadleaf weeds, woody shrubs and vines
in grapes, berries and orchard crops, including both fruits and nuts. It also
is used on residential and commercial/industrial lawns and turf, golf course
turf, ornamentals and shade trees, Christmas tree plantations,
fencerows/hedgerows, nonagricultural rights-of-way, and uncultivated areas
including patios, paths, paved areas and power stations. Oryzalin is used
most on turf, almond orchards and grapes. Formulation types include
granular, wettable powder, water dispersible granules, emulsifiable
concentrate, flowable concentrate and liquid.
Oryzalin was first registered in the U.S. as a pre-emergence herbicide
in 1974. EPA issued a Registration Standard for oryzalin in 1987 (NTIS
#PB90-174137), and a Data Call-in notice in 1991. Currently, one
technical product, two formulation intermediates and 35 end-use products
containing oryzalin are registered.
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Human Health Toxicity
AsS6SSm6nt In acute toxicity studies using laboratory animals, oryzalin is
practically non-toxic by the oral route and has been placed in Toxicity
Category IV (the lowest of four categories) for this effect. It is of moderate
dermal and inhalation toxicity and causes slight eye irritation, and has been
placed in Toxicity Category III for these effects. No skin sensitization
occurred in tests on guinea pigs.
In subchronic toxicity studies, oryzalin caused the accumulation of an
iron-containing pigment in the kidneys of rats, an increase in the weights of
several organs in mice, and blood, bone marrow and liver effects in beagle
dogs.
Oryzalin is carcinogenic in rats, based on an increase in mammary
gland tumors in females and skin and thyroid tumors in both sexes. It has
been classified as a Group C carcinogen—that is, a possible human
carcinogen for which there is limited animal evidence.
Another chronic toxicity study using beagle dogs showed effects to the
blood, liver, kidneys and thyroid gland. In developmental toxicity studies
using rats, oryzalin caused reduced maternal body weight gain as well as
decreased fetal body weights, an increase in runts and bone development
effects. In rabbits, it caused reduced maternal food consumption and weight
gain, fetal effects and reduced litter size. Reproduction studies using rats
showed increased liver and kidney weights, and decreased food consumption
and body weight gain. Oryzalin was not mutagenic in several studies. A
dermal irritation study using the oryzalin technical product is required as
confirmatory data.
Dietary Exposure
People may be exposed to residues of oryzalin in the diet when
consuming treated food commodities including almonds, avocados, citrus
fruits, figs, kiwi fruits, olives, pistachios, pome fruits (apples and pears),
pomegranates, small fruits (berries and grapes), stone fruits, tree nuts,
guavas and papayas. Tolerances or maximum residue limits are established
for these commodities (please see 40 CFR 180.304(a) and (b)), have been
reassessed and are acceptable. Tolerances established for several other food
crops will be revoked since no registrations for these uses currently exist.
A new tolerance has been proposed for green coffee beans.
Available data indicate that residues of oryzalin do not concentrate in
processed food or feed; therefore, no food/feed additive tolerances are
established or required. If studies currently underway indicate that residues
do, in fact, concentrate in processed foods, EPA will not be able to set such
tolerances for oryzalin due to the Delaney Clause in Section 409 of the
Federal Food, Drug, and Cosmetic Act (FFDCA), which prohibits the
establishment of food/feed additive tolerances for substances that cause
cancer in test animals or humans.
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No international Codex Maximum Residue Levels (MRLs) have been
established or proposed for oryzalin.
EPA has assessed the dietary risk posed by oryzalin. For each of the
population groups and subgroups analyzed, chronic dietary exposure is less
than 175,000th of the Reference Dose (RfD), an amount believed not to cause
adverse effects if consumed daily over a 70-year lifetime. The dietary
excess cancer risk for the entire U.S. population is estimated to be 8.1 x 10
7', or 8.1 extra incidences of cancer in 10,000,000. When tolerances for
unregistered commodities are revoked, the upper bound excess cancer risk
estimate will be even lower—4.5 x 10 7, or 4.5 extra cancer cases in 10
million.
Occupational and Residential Exposure
Pesticide handlers (mixers, loaders and applicators) may be exposed to
oryzalin during application. EPA conducted a limited exposure/risk
assessment based on available data, examining seven major exposure
scenarios for private and commercial applicators. Low pressure handwand
application was found to have the highest exposure and risk potential. The
private applicator using handwand equipment has an excess risk of 2.6 x 10
5, or 2.6 extra cancer incidences in 100,000. The commercial applicator
using handwand equipment, who is exposed more frequently, has the
greatest estimated excess cancer risk; that is, 2.6 x 104, or 2.6 extra cancer
cases in 10,000. To mitigate these risks, workers will be required to wear
chemical-resistant boots during low pressure handwand application. This
will reduce exposure below the knees, which is significant.
The Worker Protection Standard (WPS) requires workers handling
oryzalin to wear long pants, long sleeved shirts and chemical-resistant
gloves. Because the pesticide is a possible human carcinogen, EPA also is
requiring the use of coveralls and chemical resistant footwear for all uses of
oryzalin (except homeowner uses).
Post-application/reentry exposure also is of concern, and reentry data
are not available to calculate a Restricted Entry Interval (REI). For
agricultural and ornamental crops where reentry exposure is likely, EPA is
requiring an REI of 24 hours instead of 12 hours as imposed by the WPS.
When residential lawns are treated with oryzalin, there is a potential
for continued, substantial contact with treated surfaces, especially among
children. EPA is concerned about these postapplication exposures because
oryzalin is a possible human carcinogen and is persistent. Because of the
lack of turfgrass exposure data, however, the safety of this use cannot be
evaluated. Such exposure data are required by the RED document. Until
they are submitted and evaluated, the residential lawn and turf use of
oryzalin is not eligible for reregistration.
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Human Risk Assessment
Oryzalin generally is of moderate acute toxicity, but is carcinogenic in
animal studies and has been classified as a Group C, possible human
carcinogen. Several food crop uses, including grapes and a variety of fruits
and nuts, are registered. However, dietary exposure to oryzalin residues in
foods is extremely low, as is the cancer risk posed by this pesticide to the
general population.
Of greater concern is the risk posed to oryzalin handlers (mixers,
loaders and applicators), and to field workers and others who come into
contact with treated foliage, crops, lawns or turf following application of
this herbicide. Exposure and risk to all applicators will be mitigated by the
use of personal protective equipment (PPE) required by the Worker
Protection Standard (WPS), supplemented by coveralls and chemical-
resistant footwear, as required by this RED.
Post-application reentry workers will be required to observe a 24-hour
Restricted Entry Interval (REI), which is twice as stringent as that set forth
by the WPS. The residential lawn and turfgrass use of oryzalin is not
eligible for reregistration until post-application exposure studies are
submitted to EPA and evaluated.
Environmental Environmental Fate
AsSGSSITIGnt Parent oryzalin biodegrades slowly with a half-life of approximately
two months. It is not mobile under field conditions and is not volatile.
However, up to 20% of the oryzalin degradates may leach. The registrant
is conducting a study to determine whether degradate leaching is a major
route of dissipation.
Ecological Effects
A preliminary risk screening based on available data indicates that,
from an acute toxicity perspective, oryzalin is moderately toxic to
freshwater fish and invertebrates, and practically nontoxic to birds, small
mammals and honeybees. As would be expected of a herbicide, oryzalin
poses an acute risk to non-target plants, including threatened and endangered
plants.
Ecological Effects Risk Assessment
Minimal risks to birds are posed from acute and dietary exposure to
oryzalin. Chronic risks are not posed at single application rates of 4 pounds
active ingredient per acre (4 Ib ai/A) or less. However, EPA is unable to
determine whether higher application rates pose a serious avian reproduction
threat, and is requiring further studies to complete an assessment of chronic
avian risks.
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Additional Data
Required
Product Labeling
Changes Required
Oryzalin does not appear to pose a risk to nonendangered freshwater
fish. However, a Daphnia life-cycle study is needed to determine the
chronic risk to freshwater invertebrates. Acute toxicity studies also are
needed to determine the risks to estuarine and marine organisms.
Oryzalin poses a risk to endangered aquatic species in shallow water
adjacent to treated areas. It also poses a high risk to nontarget plants,
including endangered and threatened plants, from runoff and spray drift.
These risks will be addressed through implementation of the Endangered
Species Protection Program.
Meanwhile, the technical producer of oryzalin has agreed to take
several measures to reduce the pesticide's environmental risks. To mitigate
exposure problems associated with spray drift, airplane and helicopter
applications will no longer be allowed except to agricultural crops in
California. In addition, labeling changes are being required to reflect the
maximum amount of oryzalin that may be applied per year, the maximum
number of applications and the interval between applications.
EPA is requiring the following additional generic studies for oryzalin
to confirm its regulatory assessments and conclusions: Avian Reproduction
(mallard and quail); Acute Toxicity to Estuarine and Marine Organisms
(fish, mollusk and shrimp); Aquatic Invertebrate Lifecycle; Dermal
Irritation; Leaching/Adsorption/Desorption (underway); Spray Drift;
Storage Stability (apples and grapes, underway); and Processing Studies
(citrus and olives, underway). In addition, Mixer/Loader/Applicator
Exposure Monitoring studies are required for low pressure handwand
application including Estimation of Dermal Exposure at Outdoor Sites and
Estimation of Inhalation Exposure at Outdoor Sites. Reentry Protection
studies are required for use of oryzalin on residential lawns and turf
including: Foliar Dislodgeable Residues; Soil Dislodgeable Residues;
Estimation of Dermal Exposure; and Estimation of Inhalation Exposure.
The same studies (except Soil Dislodgeable Residues) also are required for
Christmas tree and field-grown rose uses of oryzalin.
The Agency also is requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of
Formula (CSF) and revised labeling for reregistration.
All oryzalin end-use products must comply with EPA's current
pesticide product labeling requirements, and with the following:
Worker Protection Standard (WPS)
POST-APPLICATION REENTRY RESTRICTIONS
0 WPS Uses - A 24 hour Restricted Entry Interval (REI) is required for
all oryzalin end-use products registered for uses that are within the scope of
the WPS.
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0 Non-WPS Uses - The following entry prohibitions are required:
• For Liquids: "Keep all persons, children and pets out of the
treated area until sprays have dried."
• For Dry Formulations: "Keep all persons, childrena nd pets out of
the treated area until dusts have settled."
• For All Other Non-WPS Formulations including Those for
Residential Use: "Keep all persons, children and pets out of the
treated area until sprays have dried or dusts have settled."
PERSONAL PROTECTIVE EQUIPMENT (PPE) REQUIREMENTS
0 WPS Occupational Uses and Non-WPS Uses - The minimum PPE
requirements for pesticide handlers are:
- Coveralls over long-sleeved shirt and long pants;
- Chemical resistant gloves;
- Chemical resistant footwear;
- Chemical resistant headgear for overhead exposures; and
- Chemical resistant apron (mixers and loaders).
° Homeowner Uses - The minimum PPE requirements are:
- Long-sleeved shirt and long pants; and
- Chemical resistant gloves.
WITH ENGINEERING CONTROLS
° When handlers use closed systems, enclosed cabs or aircraft in a
manner consistent with the WPS, the requirements above may be modified
or reduced. See the WPS for specifics.
USER SAFETY STATEMENTS
° Follow manufacturer's instructions for cleaning/ maintaining PPE. If
no such instructions exist for washables, use detergent and hot water. Keep
and wash PPE separately from other laundry.
° Discard clothing and other absorbent materials that have been
drenched or heavily contaminated with this product's concentrate. Do not
reuse them.
° Users should wash hands before eating, drinking, chewing gum, using
tobacco, or using the toilet.
° Users should remove clothing immediately if pesticide gets inside.
° Users should 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.
° For WPS and non-WPS uses, 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.
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Regulatory
Conclusion
For More
Information
Precautionary Statement for Fish - To protect fish, all oryzalin end-use
product labels must include the following statement:
"This product is toxic to fish. Do not apply this product directly to
water, or to areas where surface water is present, or to intertidal areas
below the mean high water mark."
Grazing Restrictions - All oryzalin end-use products must include the
following statement:
"Do not graze or feed forage from treated fields or orchards to
livestock."
Changes in Directions for Use - All end-use labels must bear specific
application rates, number of applications per year, total pounds active
ingredient per year, and intervals between applications, as specified in Table
12 of the oryzalin RED document.
Restriction on Aerial Application - All end-use product labels must
prohibit aerial application except for agricultural uses in California.
EPA has determined that products containing oryzalin are eligible for
reregistration except products labeled for use on residential lawns and turf.
The use of eligible oryzalin products in accordance with labeling
specified in this RED will not pose unreasonable adverse effects to humans
or the environment. These products will be reregistered once the required
confirmatory generic data, product specific data, Confidential Statements of
Formula and revised labeling are received and accepted by EPA. Products
which contain active ingredients in addition to oryzalin will be reregistered
when all of their other active ingredients also are eligible for reregistration.
EPA does not have enough information at this time to make an
eligibility decision for oryzalin products labeled for use on residential lawns
and turf. The Agency is requiring additional data in order to develop a
more complete database regarding these uses of oryzalin.
EPA is requesting public comments on the Reregistration Eligibility
Decision (RED) document for oryzalin 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 oryzalin 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 oryzalin RED, or reregistration of individual products containing
oryzalin, please contact the Special Review and Reregistration Division
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(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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