United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508C)
EPA-738-FOO-009
September 2000
R.E.D. FACTS
Pesticide
Reregistration
Ethyl Parathion
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 the safely standard of
the FQPA 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
serves as and explains the Agency's Reregistration Eligibility Decision for case
0155, ethyl parathion.
Use Profile Ethyl parathion is a restricted use organophosphate insecticide/miticide used
to control a broad spectrum of pests on alfalfa, barley, canola, corn, cotton,
sorghum, soybeans, sunflowers, and wheat. It is formulated as a liquid and may be
applied only using aerial equipment.
Regulatory
History
Ethyl parathion was first registered as a pesticide in the U.S. in 1948. EPA
issued a Registration Standard for ethyl parathion in December 1986 that stated the
Agency planned to initiate a Special Review due to acute human and avian
concerns. In 1991, the Agency and the registrants of ethyl parathion reached an
agreement under which the registrants agreed to limit use sites and restrict
application and post-application practices. This action was taken by the Agency to
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Human Health
Assessment
mitigate risk to workers exposed during application and post-application. (Federal
Register Notice Volume 56, No. 240, November 13, 1991; and Volume 57, No.
19, January 29, 1992; and No. 34, February 20, 1992}.
Since 1991, the use of ethyl parathion in the United States has been limited to
nine crops: alfalfa, barley, canola (rapeseed), corn, cotton, sorghum, soybeans,
sunflowers, and wheat. All of the technical ethyl parathion sold in the United
States is produced by Cheminova Agro A/S, formulated at one location and sold
under the Cheminova label. Two formulations of ethyl parathion are currently being
sold in the United States: Parathion SEC (emulsifiable concentrate) and Ethyl
Methyl Parathion 6-3 EC. A third formulation, 4EC, is registered but is not
currently marketed. Additionally, seven other registrants hold a total of 15 product
registrations; none, however, are currently marketed.
Due to the high estimated risks based on the best information available to the
Agency, and the registrants' decision not to support the data requirements for
reregistration, the registrants have signed an agreement to voluntarily cancel their
registrations. Cancellation of manufacturing use products is effective immediately,
and end use products will be canceled effective December 31, 2002, with last legal
use on October 31, 2003. Additionally, ethyl parathion end use product labels will
be amended to delete use on corn grown for seed, the site with the highest potential
risk to reentry workers, and add the last legal use date.
Toxicity
Ethyl parathion is among the most highly toxic chemicals registered with
EPA. It has been placed in Acute Toxicity Category 1 (most toxic) for acute eye,
skin, and inhalation effects. It is a potent plasma, red blood cell and brain acetyl
cholinesterase inhibitor. It is toxic by all routes of exposure and cholinesterase
inhibition occurs following acute, subchronic and chronic exposures to low doses of
ethyl parathion.
Dietary Exposure
People may be exposed to residues of ethyl parathion through the diet.
Acute dietary risk estimates for the US population or US population subgroups,
including infants and children, are equal to or less than 3% of the Agency
established acute population adjusted dose (aPAD) for parathion. Chronic dietary
risk estimates for the general US population, or population subgroups, are less than
1% of the chronic population adjusted dose (cPAD). The Agency considers
dietary risk estimates of less than 100 percent of the aPAD or cPAD to be below
the level of concern. Dietary risk is low since a low percentage of the crops are
treated and the treated commodities are generally highly processed prior to
consumption. Water modeling estimates predict that there may be a potential
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dietary risk from ethyl parathion in drinking water. The Agency did not review any
water monitoring data for ethyl parathion and with the phase-out of all ethyl
parathion products, no monitoring data are being required.
Tolerances
Tolerances or maximum residue limits for ethyl parathion and its methyl
homolog (methyl parathion) have been established for several commodities (please
see 40 CFR 180.121). EPA anticipates publishing a notice which separates the
tolerances into ethyl parathion tolerances and methyl parathion tolerances. This
notice will propose revocation for commodities for which there has been no
registered use of either parathion for a number of years. Tolerances for
commodities from the nine crops for which the last legal use is October 31, 2003,
will remain at the designated level until these commodities have cleared the channels
of trade.
Occupational and Residential Exposure
Based on current use patterns, handlers (mixers, loaders, and applicators)
may be exposed to unacceptable levels of ethyl parathion during and after normal
use, even when workers have employed engineering controls and the maximum
level of personal protective equipment. Margins of Exposure (MOEs) of 100 and
greater are considered to be below the level of risk concern. For ethyl parathion,
many of the MOEs were below 1.
Postapplication worker risk is also an issue with ethyl parathion, with
estimated safe reentry intervals at greater than 40 days after application.
Human Risk Assessment
Ethyl parathion is of extremely high acute toxicity by causing cholinesterase
inhibition. It has been classified as a Group C, possible human carcinogen, but
cholinesterase inhibition is caused by doses far below those eliciting carcinogenic
effects. However, dietary exposure to ethyl parathion residues in foods is
extremely low, as is the cancer risk posed to the general population.
There are no residential uses of ethyl parathion. The main route for
residential exposure would result from spray drift from agricultural applications.
The method for assessing this exposure is still in development; therefore no
residential exposure was considered for ethyl parathion.
Of greater concern is the risk posed to workers, particularly
mixers/loaders/applicators, and field workers who come into contact with treated
foliage and crops following ethyl parathion applications.
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FQPA Considerations
Based on a weight of evidence of all submitted data, no increased
susceptibility of rat and rabbit fetuses to ethyl parathion is observed. Therefore, the
FQPA safety factor for special sensitivity was not used in the ethyl parathion dietary
risk assessment.
No aggregrate assessment was conducted since no residential exposure was
assessed.
Environmental
Assessment
Use of ethyl parathion poses a high risk to nontarget organisms in terrestrial
and aquatic environments.
Environmental Fate
Ethyl parathion degradation appears to be dependent on microbially
mediated degradation, soil sorption, and to a small extent photodegradation. Ethyl
parathion may be persistent in aerobic mineral soils with half-lives of up to 58 days,
but degrades rapidly in aquatic environments.
Ecological Effects and Risk Characterization
Ethyl parathion is very highly toxic to birds, fish, aquatic invertebrates and
small mammals, poses a high acute risk to birds, mammals and aquatic
invertebrates, and also poses a high chronic and reproductive risk to birds. This
high acute, chronic, and reproductive risk would also be expected to impact many
endangered species in the ethyl parathion use area. Ethyl parathion is very highly
toxic to pollinating insects such as bees and has a well documented history of bee-
kill incidents.
Risk Mitigation
To lessen the worker and ecological risks posed by ethyl parathion use, EPA
and the registrants have agreed to the following risk mitigation measures:
N Immediately stop import of technical ethyl parathion.
N Immediately cancel the registrations of all ethyl parathion manufacturing use
products.
N Immediately stop use on corn grown for seed.
N Cancel end use product registrations effective December 31, 2002.
N Stop sale and distribution of all ethyl parathion products by registrants by
December 31,2002.
N Stop sale and distribution of all ethyl parathion products by retailers by
August 31,2003.
N Stop all use of ethyl parathion products by October 31, 2003.
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Additional Data
ReQ U i T0d
All previously issued Data-Call-ins regarding ethyl parathion are considered
to ^e unnecessary since all products are to be canceled. No additional data are
required at this time.
Product Labeling
Changes
All end-use products must comply with EPA's current pesticide product
labeling requirements and must be modified to include the following:
Required N
Add "not for use on corn grown for seed" in the Directions for Use section
for corn.
"It is unlawful to use this product after October 31, 2003. This container
and any contents remaining after October 31, 2003 shall be disposed of in
accordance with State and Federal law."
Regulatory
Conclusion
The companies holding ethyl parathion product registrations have requested
cancellation under FIFRA section 6(f), of all products containing ethyl parathion as
an active ingredient. EPA intends to grant this cancellation request after a 30-day
public comment period following the publication of the 6(f) notice in The Federal
Register. EPA intends to initiate Notice of Intent to Cancel procedures for the
registrations which were not requested for cancellation since there will be no legal
source of technical product after the voluntary cancellations are granted.
For More
Information
EPA is making this Reregistration Eligibility Decision (RED) Fact Sheet for
ethyl parathion available, as announced in a Notice of Availability published in the
Federal Register. To obtain a copy of the Fact Sheet 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 this RED Fact Sheet are available on the Internet. See
http://www.epa.gov/REDs.
Printed copies of the RED 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 ethyl parathion RED Fact Sheet 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 ethyl
parathion RED, or the status of individual products containing ethyl parathion,
please contact the Special Review and Reregistration Division (7508C), 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 Pesticide Telecommunications Network (NPTN). 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
ace.orst.edu/info/nptn.
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