United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508C)
EPA-738-F-98-016
November 1998
R.E.D. FACTS
Pesticide
Reregistration
DICOFOL
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. 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 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
0021, dicofol.
Use Profile
Regulatory
History
Dicofol is an organochlorine miticide/pesticide used for foliar
applications, mostly on cotton, apples, and citrus crops. Other crops include:
strawberries, mint, beans, peppers, tomatoes, pecans, walnuts, stonefruit,
cucurbits, and non-residential lawns/ornamentals. Formulations registered for
use on food/feed crops include emulsifiable concentrates, and wettable powder
formulations. These formulations may be applied as concentrated or dilute
sprays using aircraft, duster, groundboom, and sprayer.
Dicofol was first registered as a pesticide in the U.S. in 1957. EPA
issued a Registration Standard for dicofol on December 30, 1983. Data Call-
ins on September 30, 1991, March 3, 1995, and October 13, 1995 required
additional residue and ecological effects data.
Currently, 32 dicofol products are registered, including end use and
manufacturing use products.
-------
Human Health
Assessment
Toxicity
Exposure to pesticidal residues of dicofol to the U.S. population can
occur via diet through its usage on a wide array of crops, such as apples and
citrus. Occupational exposure to dicofol occurs to pesticide workers via its
agricultural application.
The Agency has calculated the chronic dietary reference dose (RfD) for
dicofol, the amount of pesticide believed not to cause adverse effects if
consumed daily over a 70 year lifetime, at 0.004 mg/kg/day based on hormonal
toxicity seen in both sexes of an oral chronic dog study.
EPA has calculated an acute dietary reference dose for dicofol, the
amount of a pesticide which can be consumed in one day and believed not to
cause adverse effects, of 0.05 mg/kg/day based on neurotoxic effects observed
after a single oral dose in a rat acute neurotoxicity study.
For the purpose of determining short-term and intermediate term worker
risk, the endpoints of concern were selected for developmental and hormonal
toxicity observed in rabbit and rat studies.
For the purposes of precautionary language for the registered product
labels, dicofol has been found to be toxicity category III (the second lowest of
four categories) for acute oral toxicity, acute dermal toxicity, acute eye
irritation, and acute dermal irritation. Dicofol has been found to be toxicity
category IV (lowest category) for acute inhalation.
Dietary Exposure
People may be exposed to residues of dicofol through the diet.
Tolerances or maximum residue limits have been established for dicofol. (See
40 CFR §180.163). The raw agricultural commodity tolerances listed under 40
CFR §180.163 are currently expressed in terms of dicofol per se, with no
animal tolerances established. The dicofol RED recommends that the listing of
tolerances for residues in/on plant commodities be designated 40 CFR
§180.163(a), and that a new section, 40 CFR §180.163(b), be provided for the
listing of animal tolerances expressed in terms of the combined residues of
dicofol and its metabolite FW-152.
The dicofol RED recommends that dicofol tolerances be revised as
follows: 1 tolerance level is recommended to be revoked, 4 tolerances are
recommended to remain unchanged, 3 tolerances are recommended to be
raised, 45 new tolerances are recommended to be established, and 33 tolerance
levels are recommended to be moved to a crop grouping. In most cases,
tolerance levels being moved to a crop grouping are also having their tolerance
levels lowered, based on new field trial data.
Chronic dietary food exposure is calculated at 38% of the RfD in the
most at-risk population (children, 1-6 years), not enough to cause concern.
Acute dietary exposure estimates, while higher (90% of RfD in the most at-risk
-------
population, non-nursing infants, less than 1 years old), still do not exceed the
Agency's Level of Concern.
When possible exposure to pesticidal residues of dicofol through
drinking water, taken from conservative modeling estimates, are included in the
dietary assessment, the Agency still does not have a risk concern for any
population subgroup with either acute or chronic dietary exposure.
Occupational and Residential Exposure
The risk assessment in this RED raises some strong concerns for dicofol
mixers/loaders/applicators, and field workers. The endpoint of concern is
hormonal and developmental toxicity. At the present time, most short term
and all intermediate term scenarios result in Margin of Exposures (MOEs)
which exceed the Agency's level of concern, even with engineering controls.
However, the Agency believes that the default assumptions used to arrive at
this conclusion may have led to an overestimation of that risk (i.e. the default
assumption of 100% dermal absorption and a initial Dislodgeable Foliar
Residue (DFR) level at 20% of the application rate and assuming residue
dissipation of 10% per day). To improve our estimation of dicofol risk, the
registrants have initiated a dermal toxicity study, which is due to the Agency
on December 31, 1998. In addition, as a result of a Data Call In from October
13, 1995, the registrants are also completing a DFR study, due in October,
1998. EPA will consider results of these studies in a revised risk assessment.
In the interim, while this data is being developed and evaluated, the registrants
have agreed to undertake risk mitigation measures (described in the Risk
Mitigation section of this Fact Sheet) to address the occupational risks
identified in this RED.
EPA will revise the Restricted Entry Interval (REI) based upon results
of the dermal toxicity study and DFR study.
Because all residential uses are being voluntarily canceled by the
registrants, residential risk is not a concern.
FQPA Considerations
EPA conducted additional risk analyses using available data in response
to the new FQPA requirements. Based upon data evaluated by the Agency,
the 10X FQPA safety factor is being reduced to 3X for all population
subgroups for both chronic and acute dietary risk.
The Agency has not made a determination whether dicofol or any other
pesticide has a common mechanism of toxicity for either cancer or non-cancer
effects and require a cumulative risk assessment. For the purposes of this
RED, EPA has considered only the risks from dicofol. If required, cumulative
risks will be assessed when methodologies for determining common mechanism
of toxicity and for performing cumulative risk assessments are finalized.
-------
Environmental
Assessment
Environmental Fate
Dicofol has a short to intermediate half-life (days to months) in
laboratory studies. Major routes of dissipation are hydrolysis in neutral and
alkaline environments and microbial-mediated degradation. Dicofol is likely to
be more persistent in acidic than neutral or alkaline soils or waters and in drier
conditions. Laboratory and field data suggest that dicofol is not very mobile,
and neither leaching nor volatility are expected to play an important role in the
dissipation of dicofol.
Ecological Effects
Dicofol is moderately to slightly toxic on an acute basis to terrestrial
animals and slightly toxic to honey bees. Dicofol has also been shown to cause
reproductive effects in avian and mammalian species. For avian species,
laboratory studies suggest that reproductive sensitivity varies greatly, with
raptors apparently the most sensitive. Dicofol is highly to very highly toxic to
all aquatic organisms tested, including fish, invertebrates, and estuarine/marine
organisms.
Ecological Effects Risk Assessment
Acute risks to non-target mammals from exposure to dicofol may occur
for citrus, apples, pears, nuts, and quince uses from exposure to short grass
food sources. Because many small mammal species primarily feed on short
grass, acute hazard from these use patterns is possible. For avian species,
exposure to dicofol in short grass exceeds the Level of Concern (LOG), based
on current uses. Since few if any avian species feed solely or even primarily on
short grass, the acute hazard from this use does not present an unacceptable
risk.
Chronic hazard, in the form of reproductive impairment to mammalian
and avian species, can occur for all currently registered use patterns.
For certain avian species, numerous reproductive parameters may be
adversely affected by exposure to dicofol. Greatest risk appears to be from
citrus. Laboratory data suggest that, for certain avian species, numerous
reproductive parameters may be adversely affected by exposure to dicofol,
based on present uses.
In aquatic environments, fresh and salt water fish, shellfish, and
invertebrates are potentially at risk from direct contamination of dicofol to the
water. Indirect contamination is also a concern
Labeling and other risk mitigation measures recommended in Chapters 4
and 5 of the dicofol RED are sufficient to address these environmental risk
concerns.
-------
Risk Mitigation To address risks to homeowners, residents, and children:
( All residential uses have been eliminated from labels and will be
voluntarily canceled.
To address risks to handlers:
( Mixers/loaders/applicators must wear additional personal
protective equipment (PPE), as specified in the labeling specifics in
Chapter 5 of the RED, and use enclosed cabs and cockpits.
( All wettable powder formulations produced after December 31,
1998 must be produced in water soluble packaging (WSP).
( Application with handheld equipment is eliminated for liquid
formulations.
( Liquid formulations produced after December 31, 1998 must bear
labeling requiring closed mixing systems for dry beans.
To address risks to workers (persons entering treated areas following
applications of dicofol):
( A revised REI will be set, based on DFR data being submitted in
October, 1998, and on a dermal toxicity study being submitted in
December, 1998.
To protect the environment and wildlife:
# Dicofol applications are limited to no more than one per year.
Previously, for some uses, the number of applications allowed per
year was either unrestricted or limited to 2 or 3 applications per
year.
# Dicofol applications on citrus will not exceed 3 pounds a.i./acre
per year. This has been reduced from 8 pounds a.i./acre per year.
# Dicofol applications on strawberries will not exceed 2 pounds
a.i./acre per year. This has been reduced from 2.4 pounds a.i./acre
per year.
# Additionally, as a result of previous agreements with the
registrants, applications will not exceed:
3 Ib ai/acre for apples and pears (reduced from 4 Ib ai/acre);
2 Ib ai/acre for pecans and walnuts (reduced from 4 Ib ai/acre);
1.5 Ib ai/acre for cotton (reduced from 1.6 Ib ai/acre);
1.3 Ib ai/acre for grapes (reduced from 1.5 Ib ai/acre);
0.63 Ib ai/acre for cucurbits (reduced from 1.5 Ib ai/acre);
0.75 Ib ai/acre for tomatoes and peppers (reduced from .8 Ib
ai/acre);
-------
#
1.5 Ib ai/acre for stonefruits;
1.5 Ib ai/acre for beans; and
0.55 Ib ai/acre for nonresidential lawns and ornamentals.
A spray drift and Runoff Caution Statement is being added to the
label. Also, a statement prohibiting application directly to water is
being added to the label.
Additional Data
Required
Product Labeling
Changes Required
Regulatory
Conclusion
All dicofol products must comply with EPA's current pesticide product
labeling requirements. For a comprehensive list of labeling requirements, see
Chapter 5 of the dicofol RED document.
EPA is requiring the following additional generic studies for dicofol to
confirm its regulatory assessments and conclusions: a UV/visible absorption
study, DFR study, dermal toxicity study, and postnatal developmental
neurotoxicity study in addition to other confirmatory studies listed in Chapter 5
of the dicofol RED.
The Agency also is requiring product-specific data including revised
Confidential Statements of Formula (CSFs) and revised labeling for
reregistration. In addition, the Agency is requiring certain confirmatory data,
as detailed in Chapter 4 of the dicofol RED document.
All dicofol end-use products must comply with EPA's current pesticide
product labeling requirements. For a comprehensive list of labeling
requirements, please see the dicofol RED document, chapter 5.
EPA has determined that products containing dicofol may be eligible for
reregistration, as specified in the dicofol RED, contingent upon results of a
dermal toxicity study due to the Agency in December 1998.
The registrants have agreed to a voluntary cancellation of all dicofol
products, which will go into effect if, after a review of the dermal toxicity
study, MOEs remain unacceptable. In addition, the registrants have agreed to
the risk mitigation measures discussed in the Risk Mitigation section of this
Fact Sheet. Moreover, a restricted entry interval (REI) will be set, based on
the dermal toxicity study and a DFR study to be submitted to EPA in October
1998.
If results of the dermal toxicity study and DFR study show dicofol to be
acceptable, based upon review by the Agency's science peer review
committees and EPA management approval, dicofol products will then be
reregistered once the required product-specific data, revised Confidential
Statements of Formula, and revised labeling are received and accepted by EPA.
Products which contain active ingredients in addition to dicofol will be
reregistered when all of their other active ingredients also are eligible for
reregistration.
-------
While the current occupational risk assessment indicates possible
unacceptable risk levels, EPA has found that it is not appropriate to declare
dicofol ineligible at this time. One key consideration is the fact that the
registrants are submitting a study which may be a more appropriate study for
regulatory purposes but which the Agency has not yet received. Although the
Agency would not normally delay a decision for a study voluntarily conducted
by a registrant outside the RED timeframe, two factors make this appropriate
here. First, the registrants have committed to significant risk mitigation
measures to be implemented immediately. Second, the registrants have
committed to a process that would result in automatic and voluntary
cancellation of any use which continues to have unacceptable risk after EPA
completes its review of the incoming new study, in a timeframe that is
comparable or more rapid than what EPA could achieve through its own
regulatory process.
For More
Information
EPA is requesting public comments on the Reregi strati on Eligibility
Decision (RED) document for dicofol 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 and this fact sheet are
available on the Internet. See http:www.epa.gov/REDs.
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 dicofol RED document also will be
available from the National Technical Information Service (NTIS), 5285 Port
Royal Road, Springfield, VA 22161, telephone (703) 605-6000.
For more information about EPA's pesticide reregi strati on program, the
dicofol RED, or reregistration of individual products containing dicofol, please
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 Pesticides Telecommunications Network (NPTN). Call toll-free
(800) 858-7378, between 9:30 am and 7:30 pm Eastern Standard Time,
Monday through Friday.
------- |