I UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
i
^, j-'P
'**, -rf&
VT^ WASHINGTON, D.C. 20460
OFFICE OF
PREVENTION, PESTICIDES
AND TOXIC SUBSTANCES
CERTIFIED MAIL (Document # EPA-R-01 -003)
Dear Registrant:
This is to inform you that the Environmental Protection Agency has completed its review
of the available data and public comments related to the revised human health risk assessment
for the organophosphate pesticide chlorpyrifos methyl. The attached document entitled, "Report
on FQPA Tolerance Reassessment and Risk Management Decision for Chlorpyrifos methyl"
which was approved on December 30, 2000, summarizes the Agency's assessment of the dietary
and occupational risk from chlorpyrifos methyl. Based on its review, EPA has identified risk
mitigation measures believed necessary to address the human health risks associated with the
current use of chlorpyrifos methyl. These risk mitigation measures can be found in the attached
document.
The major means by which the Agency reassesses tolerances is through its reregi strati on
process. Each pesticide registered prior to 1984 is subject to a comprehensive evaluation of its
effects on human health and the environment. Such an evaluation includes a determination of
whether the tolerances are safe. Since chlorpyrifos methyl was registered after 1984, it is not
subject to reregi strati on. However, chlorpyrifos methyl tolerances are subject to reassessment in
accordance with the Federal Food, Drug, and Cosmetic Act (FFDCA) as amended by the Food
Quality Protection Act of 1996 (FQPA). FQPA required EPA to re-evaluate tolerances existing
at the time it was passed to ensure that children and other sensitive subpopulations are protected
from pesticide risk.
The "Report on FQPA Tolerance Reassessment Progress and Risk Management Decision
for Chlorpyrifos methyl" is based on the revised human health assessment, updated technical
information, and public comments received by the Agency, all of which are available in the
chlorpyrifos methyl public docket. The docket includes both the preliminary and revised risk
assessment for chlorpyrifos methyl as well as comments on the risk assessments submitted by
the general public and stakeholders. During the Phase 5 Risk Management comment period
which ended June 27, 2000, the Agency received five comments. Subsequent to the close of the
comment period, the Agency received several hundred letters from the grain industry advising
the Agency that no alternative to chlorpyrifos methyl is currently available and asking that the
Agency allow enough time for continued use to provide for an orderly transition away from
chlorpyrifos methyl. The risk assessment and the documents supporting it are available for
viewing in the Office of Pesticide Programs Public Docket and can also be found on the
Agency's web page, www.epa.gov/pesticides/op.
-------
This document and the process used to develop it are the result of a pilot process to
facilitate greater public involvement and participation in the reregi strati on and/or tolerance
reassessment decisions for pesticides. As part of the Agency's effort to involve the public in the
implementation of the FQPA, the Agency is undertaking a special effort to maintain open public
dockets on the organophosphate pesticides and to engage the public in the reregi strati on and
tolerance reassessment processes for these chemicals. This open process follows the guidance
developed by the Tolerance Reassessment Advisory Committee (TRAC), a large multi-
stakeholder advisory body which advised the Agency on implementing the new provisions of the
FQPA. The reregi strati on and tolerance reassessment reviews for the organophosphate
pesticides are following this new process which has been expanded to include decisions and
other classes of chemicals, as well.
Please note that the chlorpyrifos methyl risk assessment concerns only this particular
organophosphate. It does not address the cumulative effects of other organophosphates as a
class. Because FQPA directs the Agency to evaluate food tolerances on the basis of cumulative
risk from substances sharing a common mechanism of toxicity, such as the toxicity expressed by
the organophosphates through a common biochemical interaction with cholinesterase, the
Agency will evaluate the cumulative risk posed by the entire organophosphate class of chemicals
after completing risk assessments for individual organophosphates. This document represents
the Agency's final decision on the registration of chlorpyrifos methyl and an interim decision
regarding tolerances. The Agency will issue its final decision regarding the tolerances for
chlorpyrifos methyl when the cumulative assessment for all organophosphates has been
completed.
This document contains labeling needed for chlorpyrifos methyl products. End-use
product labels should be revised by the manufacturer in order to adopt changes set forth in
Section IV of this document. Instructions for registrants on submitting revised labeling and the
time frame needed are in Section V of this document.
If you have questions on this document, please contact the Special Review and
Reregi strati on Division representative, Stephanie Nguyen at (703) 605-0702.
Sincerely yours,
Lois A. Rossi, Director
Special Review and
Reregi strati on Division
Enclosures
-------
Report on FQPA Tolerance Reassessment Progress D
and Risk Management Decision D
forD
Chlorpyrifos methyl D
-------
Table of Contents
Executive Summary vi D
I. Introduction ID
II. D Chemical Overview 4 D
A. Regulatory History 4 D
B. Chemical Identification 4 D
C. Use Profile 5 D
D. Estimated Usage of Pesticide 6 D
III. D Overview of Chlorpyrifos methyl Human Health Risk Assessment 6 D
A. Dietary Risk from Food 7 D
1. Toxicity 7 D
2. FQPA Safety Factor 7 D
B. Dietary Risk from Drinking Water 9 D
C. Aggregate Risk 9 D
D. Occupational Risk 9 D
1. Toxicity 9 D
2. Exposure 11D
3. Handler Risk Characterization 14 D
4. Postapplication Risk Characterization 15 D
IV. D FQPA Tolerance Reassessment Progress & Risk Management Decision 15 D
A. Tolerance Reassessment Progress & Risk Management Decision 15 D
B. Summary of Phase 5 Comments and Revisions to the Risk Assessment ... 16 D
C. Regulatory Position 17D
1. FQPA Assessment 17D
a. "Risk Cup" Determination 17D
b. Tolerance Summary 18 D
2. Endocrine Disrupter Effects 20D
3. Label Modifications 20D
D. Regulatory Rationale 20D
1. Dietary (Food) Risk Mitigation 20D
2. Dietary (Water) Risk Mitigation 20D
3. Aggregate (Food + Water) Risk Mitigation 20 D
4. Occupational Risk Mitigation 21D
V. D What Registrants Need to Do 21D
A. Generic Data Requirements 21D
B. Manufacturing Use Products 22 D
C. End-Use Products 22D
D. Existing Stocks 22D
E. Transition Strategy 23 D
F. Labeling 24D
-------
G. Procedure and Timing for Label Amendment 27 D
VI. D Related Documents and How to Access Them 27 D
References: 28D
Appendix A: Use Patterns Allowed during Phase-out 29 D
-------
Chlorpyrifos methyl TEAM
Office of Pesticide Programs:
Health Effects Risk Assessment
Jess Rowland D
Steven KniznerD
Gary Bangs D
John Doherty D
Michelle CentraD
Sarah Levy D
Registration Support
Dennis McNeilly
Use and Usage Analysis
William Gross
Tim Keily
Risk Management
KathyMonkD
Richard Dumas D
Stephanie NguyenD
Jackie GwaltneyD
Health Effects Division
Reregi strati on
Reregi strati on
Reregi strati on
Reregi strati on
Reregi strati on
Reregi strati on
Branch III
Branch III
Branch III
Branch III
Branch III
Branch III
Registration Division
Insecticide/Rodenticide Branch
Biological and Economic Analysis Division
Herbicide and Insecticide Branch
Economic Analysis Branch
Special Review and Reregi strati on Division
Reregi strati on Branch II
Reregi strati on Branch II
Reregi strati on Branch II
Reregi strati on Branch II
-------
GLOSSARY OF TERMS AND ABBREVIATIONS
AE Acid EquivalentD
a.i. Active IngredientD
AGDCI Agricultural Data Call-In D
ai Active IngredientD
aPAD Acute Population Adjusted Dose D
AR AnticipatedResidueD
ARC Anticipated Residue Contribution D
BCF Bioconcentration Factor D
CAS Chemical Abstracts ServiceD
CI Cation
CNS Central Nervous System
cPAD Chronic Population Adjusted Dose
CSF Confidential Statement of Formula
CFR Code of Federal Regulations
CSFII USDA Continuing Surveys for Food Intake by Individuals
DCI Data Call-In
DEEM Dietary Exposure Evaluation Model
DFR Dislodgeable Foliar Residue
ORES Dietary Risk Evaluation System
DWEL Drinking Water Equivalent Level (DWEL) The DWEL represents a medium
specific (i.e., drinking water) lifetime exposure at which adverse, noncarcinogenic
health effects are not anticipated to occur.
DWLOC Drinking Water Level of Comparison.
EC Emulsifiable Concentrate Formulation
EEC Estimated Environmental Concentration. The estimated pesticide concentration
in an environment, such as a terrestrial ecosystem.
EP End-Use Product
EPA U.S. Environmental Protection Agency
FAO Food and Agriculture Organization
FDA Food and Drug Administration
FIFRA Federal Insecticide, Fungicide, and Rodenticide Act
FFDCA Federal Food, Drug, and Cosmetic Act
FQPA Food Quality Protection Act
FOB Functional Observation Battery
G Gr anul ar F ormul ati on
GENEEC Tier I Surface Water Computer Model
GLC Gas Liquid Chromatography
GLN Guideline Number
GM Geometric Mean
GRAS Generally Recognized as Safe as Designated by FDA
11
-------
HAD Health Advisory (HA). The HA values are used as informal guidance to
municipalities and other organizations when emergency spills or contamination
situations occur.
HAFT Highest Average Field Trial D
HOT Highest Dose Tested D
IR Index Reservoir D
LC50 Median Lethal Concentration. A statistically derived concentration of a substance D
that can be expected to cause death in 50% of test animals. It is usually expressed
as the weight of substance per weight or volume of water, air or feed, e.g., mg/1,
mg/kg or ppm.
LD50D Median Lethal Dose. A statistically derived single dose that can be expected to
cause death in 50% of the test animals when administered by the route indicated
(oral, dermal, inhalation). It is expressed as a weight of substance per unit weight
of animal, e.g., mg/kg.
LEL Lowest Effect Level D
LOG Level of Concern D
LOD Limit of Detect!on D
LOAEL Lowest Observed Adverse Effect Level D
MATC Maximum Acceptable Toxicant Concentration D
MCLG Maximum Contaminant Level Goal (MCLG) The MCLG is used by the Agency D
to regulate contaminants in drinking water under the Safe Drinking Water Act.
mg/kg/day Milligram Per Kilogram Per Day
mg/L Milligrams Per Liter
MOE Margin of Exposure
MP Manufacturing-Use Product
MPI Maximum Permissible Intake
MRID Master Record Identification (number). EPA's system of recording and tracking
studies submitted.
NA Not Applicable
N/A Not Applicable
NAWQA USGS National Water Quality Assessment
NOEC No Observable Effect Concentration
NOEL No Observed Effect Level
NOAEL No Observed Adverse Effect Level
NPDES National Pollutant Discharge Elimination System
NR Not Required
OP Organophosphate
OPP EPA Office of Pesticide Programs
OPPTSEPA Office of Prevention, Pesticides and Toxic Substances
Pa pascal, the pressure exerted by a force of one newton acting on an area of one
square meter.
PAD Population Adjusted Dose
PADI Provisional Acceptable Daily Intake
PAG Pesticide Assessment Guideline
PAM Pesticide Analytical Method
in
-------
PC A Percent Crop Area D
PDF USDA Pesticide Data Program D
PHED Pesticide Handler's Exposure Data D
PHI Preharvest Interval D
ppb Parts Per Billion D
PPE Personal Protective Equipment D
ppm Parts Per Million D
PRN Pesticide Registration Notice D
PRZM/EXAMSTier II Surface Water Computer Model D
Qj* The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer RiskD
Model
RAC Raw Agriculture Commodity
RBC Red Blood Cell
RED Reregi strati on Eligibility Decision
REI Restricted Entry Interval
RfD Reference Dose
RQ Risk Quotient
RS Registration Standard
RUP Restricted Use Pesticide
SAP Science Advisory Panel
SCI-GROW Tier I Ground Water Computer Model
SF Safety Factor
SLC Single Layer Clothing
SLN Special Local Need (Registrations Under Section 24(c) of FIFRA)
TC Toxic Concentration. The concentration at which a substance produces a toxic
effect.
TD Toxic Dose. The dose at which a substance produces a toxic effect.
TEP Typical End-Use Product
TGAI Technical Grade Active Ingredient
TLC Thin Layer Chromatography
TMRC Theoretical Maximum Residue Contribution
torr A unit of pressure needed to support a column of mercury 1 mm high under
standard conditions.
TRR Total Radioactive Residue
UF Uncertainty Factor
Fg/g Micrograms Per Gram
Fg/L Micrograms Per Liter
USDA United States Department of Agriculture
USGS United States Geological Survey
UV Ultraviolet
WHO World Health Organization
WP Wettable Powder
WPS Worker Protection Standard
IV
-------
Executive Summary
EPA has completed its review of available data and public comments, revised the
preliminary human health assessment, and developed the risk management measures set forth in
this report. The Agency invited stakeholders to provide proposals and suggestions on
appropriate mitigation measures before issuing its risk management decision on chlorpyrifos
methyl, however, no risk mitigation proposals were received. This "Report on FQPA Tolerance
Reassessment Progress and Risk Management Decision" includes the Agency's final decision
regarding the registration of chlorpyrifos methyl and an interim decision regarding tolerances. A
tolerance reassessment decision on remaining import tolerances will not be considered final until
the cumulative risk assessment of all organophosphate pesticides is complete. The cumulative
assessment may result in further revisions to tolerances for chlorpyrifos methyl.
Chlorpyrifos methyl is an organophosphate insecticide, registered for use on stored grain,
including wheat, barley, oats, rice, and sorghum. It was first registered in the United States in
1985 and is formulated as 2% and 3% dust and 43% liquid (emulsifiable concentrate) end-use
products. Reldan ® 2% dust is applied at a rate of 15 Ibs of product (0.3 Ibs a.i) per 1000
bushels, and Reldan ® 3% dust at 10 Ibs product (0.3 Ibs a.i) per 1000 bushels. The liquid
Reldan 4E® is diluted by mixing a label-specified quantity (depending on the type of grain) of
pesticide with 5 gallons of water for each 1000 bushels of grain; application rates range from 3.1
to 11.5 fluid oz of product (0.097 to 0.36 Ibs a.i).
Annual domestic usage of chlorpyrifos methyl is an estimated 80,000 pounds active
ingredient for approximately 267,497,000 bushels of grain. Approximately 8% of all stored
wheat, 5% of sorghum and 5% of barley are treated with chlorpyrifos methyl annually.
Overall Risk Summary
EPA's dietary (food) risk assessment for chlorpyrifos methyl indicates that neither the
acute nor chronic risks exceed the Agency's level of concern; i.e., less than 100% of the acute or
chronic Population Adjusted Dose (PAD) is utilized for the general U.S. population and all
population subgroups.
Because of the use pattern for chlorpyrifos methyl (on stored grains and inside grain
storage facilities, with no residential uses), residues in water are not anticipated and an aggregate
assessment is not required. Therefore, a drinking water exposure analysis was not conducted.
No risk mitigation, based on dietary risk estimates is necessary at this time.
There were no chemical-specific occupational exposure data available for chlorpyrifos
methyl. Therefore, the risk assessment has been performed using surrogate data from the
Pesticide Handler's Exposure Database (PHED) where available. No data, surrogate or
otherwise, were available for some pesticide handler scenarios. All but one exposure scenario
has risks of concern even when the appropriate PPE and engineering controls are utilized during
the mixing, loading and application processes.
-------
Postapplication risks include bystander exposure to dusts generated by grain being
conveyed into, out of, or within storage containers, and dermal exposure when sampling treated
grain. Personnel rarely have direct contact with the stored grain and therefore skin exposure is
only a concern during short exposures such as testing of grain or maintenance work. The
employees of a grain elevator or the farmer/operator who operates a portable auger to load
treated grain into a bin may be exposed to treated grain dust, but inadequate data are available to
quantify such exposures. Therefore, chemical-specific data for handler and postapplication
exposure to insecticidal dust are required to complete the risk assessment.
Summary of Risk Mitigation
In response to a data call-in notice requiring acute, subchronic, and developmental
neurotoxicity studies, the registrants requested voluntary cancellation of all chlorpyrifos methyl
registrations. All dust formulations have been canceled, and sales and distribution is allowed
through March 30, 2001. The use of existing stocks will be allowed through December 31,
2001, and at the end of this period, the use of the dust formulation will be canceled. Because
chlorpyrifos methyl fills an important role in pest management for certain stored grains and no
adequate alternative is currently available, cancellation of liquid formulations will not occur until
December 31, 2003, and use of all existing stocks will be permitted until December 31 , 2004,
provided certain changes are made to all product labels. The changes include deletion of all but
two uses from all product labels. Only direct treatment of grain with automated admixture
systems and empty bin treatment from outside the bin will be allowed.
Also, the Agency has requested additional data from the registrants in order to better
characterize the risk associated with this chemical. During the phase out of this chemical, the
Agency will receive from the registrants the following studies to address some of the data gaps
associated with chlorpyrifos methyl (The Agency will, if necessary, make any changes to the
registration as indicated by these data):
Acute delayed neurotoxity study in hens;
Two generation rat reproduction study;
• Acute oral toxicity -Rat;
• Acute dermal toxicity - Rabbit;
• Acute inhalation study -Rat;
• Primary ocular irritation -Rabbit;
Primary dermal irritation- Rabbit; and
Dermal sensitization study- Guinea pigs.
I. Introduction
This report on the progress toward tolerance reassessment for chlorpyrifos methyl is the
result of the pilot process developed through the Tolerance Reassessment Advisory Committee
(TRAC) to facilitate greater public involvement in the ongoing FIFRA reregi strati on and/or
FQPA tolerance reassessment initiatives on pesticides. Since chlorpyrifos methyl was first
ID
-------
registered in 1985, it is not subject to the reregi strati on process, only to the requirements of
FQPA. However, some history and background on reregi strati on and FIFRA is included here for
informational purposes and to provide a discussion of the existing laws related to pesticide
registration and use.
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended in 1988
to accelerate the reregi strati on of products with active ingredients registered prior to November
1, 1984. The amended act calls for the development and submission of data to support the
reregi strati on of an active ingredient, as well as a review of all submitted data by the EPA.
Reregi strati on involves a thorough review of the scientific database underlying a pesticide's
registration. The purpose of the Agency's review is to reassess the potential hazards arising
from the currently registered uses of the pesticide; to determine the need for additional data on
health and environmental effects; and to determine whether the pesticide meets the "no
unreasonable adverse effects" criteria of FIFRA.
On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was signed into
law. This Act amends FIFRA to require reassessment of all existing tolerances in effect at the
time of passage by 2006. The Agency had decided that, for those chemicals that have tolerances
and are undergoing reregi strati on, the tolerance reassessment will be initiated through this
reregi strati on process. FQPA amends both FIFRA and the Federal Food, Drug, and Cosmetic
Act (FFDCA), but does not amend any of the existing reregi strati on deadlines. Therefore, the
Agency is continuing its reregi strati on program while it resolves the remaining issues associated
with the implementation of FQPA. The Agency is also continuing its progress toward tolerance
reassessment as required by FQPA for all of the organophosphate chemicals, whether or not they
are subject to the reregi stration process. Until a final methodology for completion of the
cumulative assessment for all of the organophosphates is established, individual risk assessments
and risk mitigation measures, where appropriate, are being conducted. [Although not subject to
the reregi strati on process, the individual dietary assessment for the organophosphate chlorpyrifos
methyl has been completed; it will also be considered in the cumulative assessment of all of the
organophosphate chemicals to satisfy the requirements of FQPA.] This document presents the
Agency's dietary risk assessment for chlorpyrifos methyl, as part of the tolerance reassessment
process. The Agency has also revised occupational risk estimates for chlorpyrifos methyl.
As part of the EPA's effort to involve the public in the implementation of FQPA, the
Agency is undertaking a special effort to establish public dockets on the organophosphate
pesticides and to engage the public in the reregi strati on and tolerance reassessment processes for
these chemicals. The public process was discussed by the Tolerance Reassessment Advisory
Committee (TRAC), a large multi-stakeholder advisory body which advised the Agency on
implementing the new provisions of the FQPA. The reregi strati on and tolerance reassessment
reviews for the organophosphates are following this new process.
Phases 1 through 4 of the pilot process address the development and refinement of the
risk assessments. Phases 5 and 6 are concerned with the development and implementation of
risk management plans and provide opportunity for the registrants, user community, and general
public to propose risk mitigation based on the revised risk assessments. During phase 6 of the
2D
-------
process, the Agency prepares a Report on FQPA Tolerance Reassessment and Risk Management
Decision Document, from which risk management will be implemented. Prior to finalizing a risk
management decision, the Agency typically arranges a conference call with USD A, growers,
registrants, and other interested parties to assess the feasibility of proposed mitigation measures.
The Agency conducted such a conference call on December 20, 2000 for chlorpyrifos methyl.
The implementation of FQPA has required the Agency to revisit some of its existing
policies relating to the determination and regulation of dietary risk, and has also raised a number
of new issues for which policies are being developed. These issues were refined and developed
through collaboration between the Agency and the TRAC, which was composed of
representatives from industry, environmental groups, and other interested parties. The TRAC
identified the following science policy issues it believed were key to the implementation of
FQPA and tolerance reassessment:
Applying the FQPA 10-Fold Safety Factor
• Whether and How to Use "Monte Carlo" Analyses in Dietary Exposure Assessments
• How to Interpret "No Detectable Residues" in Dietary Exposure Assessments
• Refining Dietary (Food) Exposure Estimates
• Refining Dietary (Drinking Water) Exposure Estimates
Assessing Residential Exposure
Aggregating Exposure from all Non-Occupational Sources
• D How to Conduct a Cumulative Risk Assessment for Organophosphate or Other Pesticides
with a Common Mechanism of Toxicity
• Selection of Appropriate Toxicity Endpoints for Risk Assessments of Organophosphates
• Whether and How to Use Data Derived from Human Studies
The process developed by the TRAC calls for EPA to provide one or more documents for
public comment on each of the policy issues described above. Each of these issues is evolving
and in a different stage of refinement. Most issue papers have already been published for
comment in the Federal Register and others will be published shortly.
In addition to the policy issues that resulted from the TRAC process, the Agency
published in the Federal Register on a Pesticide Registration Notice that presents EPA's
approach for managing risks to occupational users from organophosphate pesticides
(www.epa.gov/pesticides/op/pr/pdf). This notice describes the Agency's approach to managing
risks to handlers and workers from organophosphate pesticides. Generally, protective measures
such as additional clothing, closed mixing and loading systems or enclosed cab equipment as
well as increased reentry intervals, will be required for most uses where current risk assessments
indicate a risk and such protective measures are feasible. The policy also states that the Agency
will assess each pesticide individually, and based upon the risk assessment, determine the need
for specific measures tailored to the potential risks of the chemical. The measures included in
this interim document are consistent with the draft Pesticide Registration Notice.
This document consists of six sections. Section I introduces the regulatory framework
for reregi strati on and tolerance reassessment reviews for the organophosphate pesticides.
3D
-------
Section II provides a profile of chlorpyrifos methyl use patterns and usage. Section III
summarizes the human health assessment. Section IV presents the Agency's regulatory position
on this chemical. Section V discusses what the manufacturer's obligations are with respect to
further actions required, and finally, Section VI provides information on how to access all related
documents. The entire revised risk assessment is not included in this document, but is available
on the Agency' s web page (www.epa.gov/pesticides/op), and in the public docket. A Notice of
Availability for this document will be published in the Federal Register.
A Notice of Availability for this document has been published in the Federal Register.
II. D Chemical Overview
A. Regulatory History
Chlorpyrifos methyl was first registered in the United States in 1985 for use as an
insecticide. This interim tolerance reassessment review is the Agency's first reevaluation of
chlorpyrifos methyl since its initial registration in 1985.
B. Chemical Identification
Chlorpyrifos methyl
Cl
I
Common Name:
Chemical Name:
Chemical Family:
CAS Registry Number:
OPP Chemical Code:
Chlorpyrifos methyl
O,O-Dimethyl-O-(3,5,6-trichloro-2-pyridyl)
phosphorothioate
Organophosphate
5598-23-0
59102
! Empirical Formula: C7H 7CL 3NO3PS
! Trade and Other Names: Reldan®
I
Basic Manufacturer:
Dow AgroSciences
A detailed discussion on the physical properties of chlorpyrifos methyl can be found in
the Chlorpyrifos methyl human health revised risk assessment: "Human Health Risk
Assessment, Chlorpyrifos methyl (April 19, 2000)" which is available in the docket and on the
4D
-------
Internet.
C.
Use Profile
methyl.
The following information is based on the currently registered uses of chlorpyrifos
Type of Pesticide: Insecticide
Summary of Use
Sites:
Food:D
Nonfood:
Residential:
Target Pests :D
Formulation Types
Registered :D
Direct grain treatment, empty flour bins, commercial storage or
warehouses and top dressing for grain in trucks and bins
Stored grain (grain crops, barley, oats, rice, sorghum, wheat, oil
crops, animal feed, grain, cereal).
None
No residential uses.
Chlorpyrifos methyl is used to control beetles, grain beetles, lesser
grain borers, and red flour beetle.
End-use product formulations: dusts containing 2% or
3% active ingredient (7501-98) and (7501-99), and a liquid
containing 43.2% active ingredient, Reldan® 4E (7501-41) and
(62719-43).
Method and Rates of Application:
Equipment -
Method and Rate -
Automated admixture systems for direct treatment of grain. Liquid
application to the walls of empty grain storage containers using
hand sprayers, such as backpack or high-pressure hand wands.
Dusts may be applied by hand or power-duster on top of grain in
storage containers, or by mixing the product with a shovel while
the grain is still in the truck.
The liquid Reldan 4 E® is diluted by mixing a label-specified
quantity (depending on the type of grain) of pesticide with 5
gallons of water for each 1000 bushels of grain; application rates
range from 3.1 to 11.5 fluid oz of product (0.097 to 0.36 Ibs a.i).
High-pressure handwand or backpack sprayer for empty grain bins
(5% of the annual usage); grain is treated by hand or power dusting
5D
-------
(top-dressing), and automated systems for liquid and dust
formulations.
Reldan 2% Dust is applied at a rate of 15 Ibs. of product (0.3 Ibs.
a.i) per 1000 bushels, and Reldan 3% Dust at 10 Ibs. product (0.3
Ibs. a.i) per 1000 bushels.
Use Classification: Chlorpyrifos methyl currently is an unclassified chemical.
D. Estimated Usage of Pesticide
Based on 1989 through 1998 usage information, the Agency estimates that chlorpyrifos
methyl's total domestic usage averages approximately 80,000 pounds active ingredient for
267,497,000 bushels treated. About 80% of the total pounds of chlorpyrifos methyl a.i. is
applied to wheat. Approximately 8% of all stored wheat, 5% of sorghum and 5% of barley are
treated with chlorpyrifos methyl.
III. Overview of Chlorpyrifos methyl Human Health Risk Assessment
Following is a summary of EPA's human health risk findings for the organophosphate
pesticide chlorpyrifos methyl, as fully presented in the document, "Chlorpyrifos methyl. Human
Health Risk Assessment. Chemical Number 059102" dated April 19, 2000. The risk assessment
forms the basis of the Agency's risk management decision for chlorpyrifos methyl. However,
the Agency must complete a cumulative assessment of the risks of all organophosphate
pesticides which will include consideration of the chlorpyrifos methyl tolerances.
Using relevant data, published scientific literature, and available surrogate data, the
Agency assessed the human health risks associated with using chlorpyrifos methyl on stored
grain, including wheat, barley, oats, rice, sorghum and post-binning (grain storage bins). There
are no residential or other non-occupational use sites and no water exposure is anticipated;
therefore, in quantifying aggregate risks, the Agency considered exposures from food only. The
results of the food analysis indicate that acute and chronic aggregate risk are not of concern.
An occupational risk assessment was also conducted for mixers, loaders, and applicators
using chlorpyrifos methyl on and around stored grain. The results are summarized below in
section D.
6D
-------
A. Dietary Risk from Food
1. Toxicity
The Agency has reviewed all toxicity studies submitted and determined that the toxicity
database is adequate to support an interim tolerance reassessment determination for all currently
registered uses. This interim determination pertains only to chlorpyrifos methyl alone and does
not consider the cumulative risk from all other organophosphates. The No Observed Adverse
Effect Level (NOAEL) of 1 mg/kg/day used in the acute dietary assessment was selected from a
rat developmental study based on inhibition of red blood cell cholinesterase activity at a Lowest
Observed Adverse Effect Level (LOAEL) of 12.5 mg/kg/day. The NOAEL = 0.1 mg/kg/day
used in the chronic dietary assessment was selected from a combined rat chronic/carcinogenicity
study based on plasma cholinesterase activity at a LOAEL of 1 mg/kg/day. At the LOAEL,
cholinesterase activity decreased 40-45%. At the next highest dose tested, 50 mg/kg/day, plasma
cholinesterase activity was depressed 85-94% and brain cholinesterase activity was depressed
37-47%.
2. FQPA Safety Factor
The FQPA lOx Safety Factor was retained. The inadequacy of the toxicological data
base precluded an evaluation of potential increased susceptibility to infants and children. A total
uncertainly factor of lOOOx (lOx for inter-species extrapolation; lOx for intra-species variability;
and the lOx FQPA safety factor) applies to all subpopulations and for all durations of exposure.
The potential for chlorpyrifos methyl to induce delayed neurotoxicity remains open because the
acute study was considered equivocal and a repeat study is needed. A subchronic hen study did
not indicate delayed neuropathy at levels up to and including 500 mg/kg/day. The
developmental toxicity assessment is considered incomplete; only a rat study is available. No
acceptable rabbit (or second species) study is available and there is no acceptable multi-
generation reproduction study. In the rat developmental toxicity study there were no
developmental effects observed at the highest dose tested (50 mg/kg/day); the maternal NOAEL
was 1.0 mg/kg/day based on decreased cholinesterase activity at the LOAEL of 12.5 mg/kg/day.
Since the developmental toxicity data base is incomplete, the assessment for increased
susceptibility to fetuses and neonates is also incomplete.
Population Adjusted Dose (PAD)
The PAD is a term that characterizes the dietary risk of a chemical, and reflects the
Reference Dose (RfD) (the maximum dose of a substance that is anticipated to have no adverse
human health effect when taken daily over a specific time period), that has been adjusted to
account for the FQPA safety factor (i.e., RfD/FQPA safety factor).
In the case of chlorpyrifos methyl, the FQPA safety factor is lOx; therefore, the acute or
chronic RfD/10 = the acute or chronic PAD. A risk estimate that is less than 100% of the acute
or chronic PAD is not of concern. An acute Population Adjusted Dose (aPAD) of 0.001
mg/kg/day was used for the acute dietary risk assessment. For the chronic dietary risk
7D
-------
assessment, a chronic Population Adjusted Dose (cPAD) of 0.0001 mg/kg/day was used. The
toxicological endpoints and uncertainty factors used in the assessments are summarized in Table
1.
Table 1: Summary of Toxicological Endpoints Used in the Human Dietary Risk
Assessment
Assessment
Acute Dietary
Chronic
Dietary
Dose
NOAEL= 1.0
mg/kg/day
LOAEL=12.5
NOAEL=0.1
mg/kg/day
LOAEL=1.0
Endpoint
Inhibition of red
blood cell
cholinesterase
Inhibition of
plasma
cholinesterase
Study
Developmental
toxicity in rats
Combined chronic/
carcinogenicity in
rats
UF
100
100
FQPA
Safety
Factor
lOx
lOx
PAD
0.001
mg/kg/day
0.0001
mg/kg/day
3. Exposure Assumptions
The Dietary Exposure Evaluation Model (DEEM™) was used to estimate the dietary
exposure based on individual consumption data from USDA's 1989-1992 nationwide Continuing
Survey of Food Intake by Individuals (CSFII). For the acute dietary assessment, risk is
calculated considering what is eaten in one day (consumption) and residues potentially present
on foods. For chronic exposures, dietary risk is calculated by using the average consumption
value for food and average residue value. These estimates are highly refined using anticipated
residues based on PDF monitoring data and percent crop treated.
4. Food Risk Characterization
Both acute and chronic dietary risk estimates for chlorpyrifos methyl are below the
Agency's level of concern (<1 00% PAD) for all population subgroups. For the highest
exposed population subgroup, children 1-6, 30% of the acute PAD is occupied, at the 99.9th
percentile of exposure. For the highest exposed population subgroup, children 1-6, 52% of the
chronic PAD is occupied.
B. Dietary Risk from Drinking Water
Because of the use pattern for chlorpyrifos methyl (on stored grains and inside grain
storage facilities), residues in water are not anticipated. Therefore, a drinking water exposure
analysis was not conducted.
C. Aggregate Risk
8D
-------
Because of the use pattern for chlorpyrifos methyl (no residential uses and no drinking
water exposure) an aggregate assessment is not required.
D. Occupational Risk
Occupational exposure to a pesticide can occur through mixing, loading, and/or applying
a pesticide, or re-entering treated sites. Handlers of chlorpyrifos methyl include: individuals
who mix, load, and/or apply chlorpyrifos methyl on and around stored grain. Risk for all of
these potentially exposed populations is measured by a Margin of Exposure (MOE) which
determines how close the occupational exposure comes to a NOAEL. The ratio of the estimated
exposure to the NOAEL is referred to as the Margin of Exposure (MOE). For chlorpyrifos
methyl, MOEs greater than 100 are not of concern.
1. Toxic ity
For the occupational short-term dermal and inhalation risk assessments, a NOAEL of 1.0
mg/kg/day was selected from an oral rat developmental study based on inhibition of red blood
cell (RBC) cholinesterase activity at the LOAEL of 12.5 mg/kg/day. For the intermediate-term
assessments, a NOAEL of 0.1 mg/kg/day based on inhibition of plasma cholinesterase activity at
the LOAEL of 1.0 mg/kg/day was selected from a combined oral rat chronic/carcinogenicity
study. A dermal absorption of 3% was used based on comparison of the oral and dermal toxicity
of chlorpyrifos-(-ethyl). This is considered reasonable due to the similarity of the physical
characteristics affecting absorption for these two chemicals. Inhalation absorption was assumed
to be 100%. The toxicological endpoints for chlorpyrifos methyl are summarized in Table 2.
Table 2. Toxicology Endpoints Selected for Occupational Risk Assessment
Assessment
Short Term (1-7 days) (Dermal)
Intermediate Term
(7 days - several months) (Dermal)
Short Term (1-7 day)
(Inhalation)
Intermediate Term
(7 days - several months) (Inhalation)
Dose (mg/kg/day)
NOAEL = 1
LOAEL=12.5
NOAEL = 0.1
NOAEL = 1
NOAEL = 0.1
Endpoint
RBC
cholinesterase
inhibition (ChEI)
Plasma
cholinesterase
activity
RBC ChEI
Plasma
cholinesterase
activity
Study
Developmental toxicity
in rats (oral)
Combined chronic/
carcinogenicity in rats
(oral)
Developmental toxicity
in rats (oral)
Combined chronic/
carcinogenicity in rats
(oral)
Absorption
Factor
3%
3%
100%
100%
9D
-------
2. Exposure
EPA has determined that there are potential exposures to mixer/loaders, applicators, and
other handlers for use-patterns associated with chlorpyrifos methyl. The major use patterns for
chlorpyrifos methyl considered in the occupational risk assessment are discussed below.
Admixture: Pesticide is mixed with grain as it enters the storage container. The labels do
not specify the type of equipment to use. For grain, Reldan ®2% Dust is applied at a rate
of 15 Ibs. of product (0.30 Ibs. a.i) per 1000 bushels, and Reldan® 3% Dust at 10 Ibs.
product (0.3 Ibs. a.i) per 1000 bushels. In contrast, the liquid Reldan® 4E is diluted by
mixing a label-specified quantity (depending on the type of grain) of pesticide with 5
gallons of water for each 1000 bushels of grain. Wheat is the largest treated commodity,
so the rate at which Reldan® 4E is applied to wheat (0.36 Ibs. a.i per 1000 bushels) is
used for assessment purposes.
Top-Dress Treatment: Pesticide is applied to the top surface of stored grain to act as a
barrier to infestation. The grain may be fumigated with another product prior to the top-
dressing. The worker/applicator may climb into the storage container to add the dust.
This can be physically stressful as the worker will typically sink in to knee depth or
deeper. Sometimes dust is blown into the container from the opening. If the grain is in a
truck or wagon, the dust formulation is applied and then "cut into the grain with a
shovel," prior to loading into the storage container. Due to the physical nature of this
task, and based on consultation with agricultural authorities, the Agency estimates one
applicator could treat a maximum of 3 large silos (2000 ft2 each) or one farm truck per
day. As a top-dressing, both the Reldan® 2% and 3% dust are applied up to 7 Ibs.
product per 1000 square feet. Reldan® 4E liquid is not used for top-dressing, based on
the label.
Empty Bin Treatment: Reldan® 4E liquid is labeled for use as a bin treatment after
removal of all grain and waste from the container. One pint of Reldan® 4E is mixed with
3 gallons of water to provide an approximately 1% spray, which is then applied to walls
and floors at one gallon per 650-1250 square feet. For assessment purposes, a one
gallon/650 square feet rate (maximum label rate) was chosen. The application rate per
day was based upon the Agency's policy for practical maximum daily spray volumes
multiplied by square footage per gallon.
Current labels for both dust and liquid formulation require rubber gloves and eye
protection. Table 3 shows the levels of personal protective equipment (PPE) assumed in the
occupational assessment.
ion
-------
Table 3 : PPE Assessed in Occupational Assessment for Chlorpyrifos methyl
Level of PPE
Minimum
Maximum
Loaders and Mixers
Long-sleeved shirt and long pants,
shoes plus socks, chemical-resistant gloves,
protective eyewear.
Coveralls over long-sleeved shirt and long
pants, shoes plus socks, chemical- resistant
gloves, protective eyewear, respirator.
Loaders/Mixers/Applicators
Long-sleeved shirt and long pants, shoes
plus socks, chemical-resistant gloves,
protective eyewear.
Coveralls over long-sleeved shirt and long
pants, shoes plus socks, chemical-resistant
gloves, protective eyewear, respirator
Handler Exposure Estimates
For several scenarios, exposure data were very limited or unavailable. The most reliable
exposure data are for mixing and loading the liquid formulation (i.e., for automated admixture
systems) and for mixer/loader/applicators of the liquid formulation to empty grain storage bins.
But only 5% of the annual usage of a.i. (based on Quantitative Usage Analysis dated 4/19/98 by
BEAD) is for treatment of empty grain storage bins, and approximately 95% is for grain
protection. Little exposure information is available for application of either the dust or liquid
product to grain. Therefore, most of the exposure estimates were surrogate values derived from
the Pesticide Handler Exposure Database (PHED) Version 1.1.
Because no PHED or EPA-reviewed study data were available for occupational exposure
from application of insecticide dust, an attempt was made to characterize the magnitude of
exposure, and also the risk, by using a study from the scientific literature. The study selected
was reported by the American Chemical Society. The study measured exposures by passive
dosimetry of 12 volunteers applying three different formulations of carbaryl - dust, wettable
powder, and aqueous suspension - to corn and beans in a garden for 15 minutes to each crop.
Although the assumption that clothing is 50% protective from dust may overestimate exposure,
and the dust formulation measured in the study was 5% a.i (vs. Reldan® 3%), the application
scenario may be a reasonable surrogate for hand applications to grain. Because the worker
applying dust to grain can be standing in the grain, it is expected that dermal exposure would be
greater than dusting plants in a garden. The risk estimates are based only on dermal exposure
because the Agency has inadequate data to assess inhalation exposure from dust formulations.
However, these data are used to provide an initial attempt to characterize the applicator's dose.
Table 4 summarizes the occupational scenarios assessed and the assumptions used for
chlorpyrifos methyl.
11D
-------
Table 4: Assumptions Used in Estimating Worker Short- and Intermediate-Term Exposure
Exposure Scenario
Application Rate
(Ibs. ai/gal or /1000 ft2 or /1000 bu.)
Daily Bushels, Ft2, or
Gallons Treated '
Mixer/Loader Exposure
Loading Dusts for Automated
Application Systems 2
Mixing/Loading Liquids for Automated
Application 3
[ex: wheat]
10 Ibs. Reldan® 3%/1000 bu
or
15 Ibs. Reldan® 2%/1000 bu
= 0.3 Ibs. ai/1000 bu
1% solution =
1 1.5 oz Reldan® 4E/5 gal H2O/1000 bu =
0.36 Ibs. ai/1000 bu
10,000 bu/hr*8hrs=
80,000 bu
10,000 bu/hr*8hrs=
80,000 bu
Mixer/Loader/Applicator Exposure
Handheld Dust Pump 4 for (a) treating
wagon or truckload or (b) top dressing
grain in storage container
Power Duster 5 for (a) treating wagon or
truckload or (b) top dressing grain
Backpack Sprayer 6
for Grain Bin and Warehouse (for
spraying walls)
High Pressure Handwand (for spraying
walls) 7
10 Ibs. Reldan® 3%/1000 bu =
0.3 Ibs. ai/1000 bu
7 Ibs. Reldan® 2-3%/1000 ft2 =
0.21 Ibs. ai/1000 ft2
b)10 Ibs. Reldan® 3%/1000 bu
or
15 Ibs. Reldan ® 2%/1000 bu
= 0.3 Ibs. ai/1000 bu
a)7 Ibs. Reldan ® 3%/1000 ft2 =
0.21 Ibs. ai/1000 ft2
1% = 8oz Reldan ® 4E/3 gal H2O=
0.25 Ibs. ai/3gal
1 gal 1% solution/650 ft2
1% = 8oz Reldan ® 4E / 3 gal H2O=
0.25 Ibs. ai/3gal
1 gal 1% solution/650 ft2
300-1000 bu/farm wagon
or truck * 10
or
7 bins/day = 3, 150 ft2
300-1000 bu/farm
wagon or truck * 10
or
7 bins/day = 3, 150 ft2
24 gal (diluted)
(15,600 ft2)
40 gal (diluted)
26,000 ft
Daily area treated (or gallons applied) values are from EPA estimates of area (or gallons) that could be treated in a single day
for each exposure scenario. Assistance was received from agricultural extension agents. For example:
•D Estimate of Mixer/Loader exposure for application of liquid Reldan 4E (43% ai) to grain (wheat):
wheat application rate for final concentration of 6 ppm = 11.5 oz product/5gal water/1000 bushels
= 0.09 gal product / 5 gallons water/ 1000 bu; = 0.09 gal x 4 Ibs. ai/ gal; = 0.36 Ibs. ai / 1000 bu;
estimated 80,000 bushels/day [10,000 bu/hr loading x 8 hrs] x 0.36 Ib ai/1000 bu = 29 Ibs. ai/day
• Hand-held duster application for truck load treatment assumes 1000 bushels/truck load.
• Hand-held duster application for grain top-dressing assumes 60,000 bu bins @ 450 ft2 x II day = 3150 ft2
• Insufficient data to characterize application rate for power duster in truck, bin, or silo
•D Backpack sprayer (3 gallons) assumed to apply maximum of 8 tanks per day due to practical limitations, assuming one
person mixing, loading and applying (MLAP). Therefore 3 gal/tank x 8 tanks=24 gal x 650 ft2 /gal= 15,600 ft2; 0.25
Ibs. ai/tank x 8 tanks = 2 Ibs. ai/day.
• High pressure handwand application assumed to apply maximum of 40 gallons per day = 40gal x 650 ft /gal = 26,000
ft2; 40gal/day x 0.25 Ibs. ai/3gal tank = 3.3 Ibs. ai/day.
Mixer
2Open loading dusts [wettable powder] for automated application systems (800 Ibs. of 3% dust or 24 Ibs. ai per day)
'Mixing/Loading liquids for automated application (400 gallons of dilute liquid or 29 Ibs. ai per day)
4 (a) Treating grain in trucks with a hand-held duster (100 Ibs. of 3% dust or 3 Ibs. ai per day)
(b) Top dressing grain with dust by hand pump inside bins (0.66 Ib. ai per day)
5 (a) Treating grain in trucks with a power duster (no data)
12D
-------
(b) Top dressing grain with dust by power duster (no data)
6 Mixing, loading, and spraying empty bins with backpack sprayers (24-40 gallons or 2-3.3 Ib ai per day)
7 Mixing, loading, and spraying empty bins with high pressure handwand sprayer (24-40 gallons or 2-3.3 Ibs. ai per day)
Postapplication Exposure
Postapplication risks include bystander exposure to dusts generated by grain being
conveyed into, out of, or within storage containers, and dermal exposure when sampling treated
grain. Personnel rarely have direct contact with the stored grain; therefore, dermal exposure is
only a concern during short exposures for testing of grain. Bystander dust exposure may be
significant for either the employee of a grain elevator or farmer/operator who operates a portable
auger to load treated grain into a bin.
Little data are available to quantify post-application risks to workers or bystanders. Exposure to
pesticide residues on grain dust during off-loading to rail cars or vessels is a potential health
hazard, as is inhalation of the grain dust itself.
3.
Handler Risk Characterization
Of the six exposure scenarios assessed, all but direct grain treatment of liquid product
using an automated system are of concern, even with maximum PPE. For mixing/loading
scenario for automated application, hand-held duster application, only dermal exposure was
assessed because no data are available for inhalation exposure. Consequently, the risk estimate
shown below may underestimate risk. The following table summarizes mixer/loader/applicator
risks:
Table 5: Summary of Combined Dermal and Inhalation MOEs
Scenario
Ibs
a.i/day
Minimum PPE l
Short-
Term
Intermedia!
e- Term
Maximum PPE2
Short-Term
Intermediate-
Term
Mixer/Loader
Open loading dust for automated
application system 3
Mixing/Loading Liquids for
automated application 4
24
29
53
1000
6.0
130
200
2700
23
320
13D
-------
Mixer/Loader/Applicator
Hand-Held Duster
(a 5)) Treating Grain in Trucks or
(b 5) Top-dressing Grain with
dust by hand-pump
Power Duster (a 6) treating grain
in trucks or (b 6) top dressing
grain with dust by power duster
Backpack Sprayer for empty bin
treatment 7
High Pressure Handwand
Sprayer for empty bin treatment 8
3
0.66
No Data
2
3.3
3.3
[dermal
only]
15
[dermal
only]
No Data
290
93
0.39
[dermal
only]
1.8 [dermal
only]
No Data
34
11
4.7 [dermal
only]
21 [dermal
only]
No Data
560
260
0.54 [dermal
only]
2.5 [dermal
only]
No Data
64
29
1 Minimum PPE consist of wearing a long-sleeved shirt. D
2 Maximum PPE consist of wearing a long-sleeved shirt plus coveralls and a respirator. D
3 Open loading dusts [wettable powder] for automated application systems (800 Ibs. of 3% dust or 24 Ibs. ai per day)D
4 Mixing/Loading liquids for automated application (400 gallons of dilute liquid or 29 Ibs. ai per day)D
5 (a) Treating grain in trucks with a hand-held duster (100 Ibs. of 3% dust or 3 Ibs. ai per day)D
(b) Top dressing grain with dust by hand pump inside bins (0.66 Ib. ai per day)D
6 (a) Treating grain in trucks with a power duster (no data)D
(b) Top dressing grain with dust by power duster (no data)D
7 Mixing, loading, and spraying empty bins with backpack sprayers (24-40 gallons or 2-3.3 Ib ai per day)D
8 Mixing, loading, and spraying empty bins with high pressure handwand sprayer (24-40 gallons or 2-3.3 Ibs. ai per day)D
4. Postapplication Risk Characterization
Postapplication risks include bystander exposure to dusts generated by grain being
conveyed into, out of, or within storage containers, and dermal exposure when sampling treated
grain. Personnel rarely have direct contact with the stored grain and therefore dermal exposure
is only a concern during short exposures for testing of grain, maintenance, or other intermittent
activities. Bystander dust exposure may be significant for either the employee of a grain elevator
or farmer/operator who operates a portable auger to load treated grain into a bin. Chemical-
specific data for postapplication exposure to insecticidal dust would be needed to complete the
risk assessment.
IV. FQPA Tolerance Reassessment Progress & Risk Management Decision
A. Tolerance Reassessment Progress & Risk Management Decision
This evaluation presents the Agency's current position on products containing the active
ingredient chlorpyrifos methyl. The Agency has sufficient information on the human health
effects of chlorpyrifos methyl to make interim decisions as part of the tolerance reassessment
14D
-------
process under FQPA. Based on its current evaluation of chlorpyrifos methyl alone, the Agency
has determined that chlorpyrifos methyl products, as labeled, will not present unreasonable
dietary risks of concern, but the occupational risks exceed the Agency's level of concern.
Recently, the registrants, Gustafson and Dow AgroSciences, submitted a request to voluntarily
cancel all chlorpyrifos methyl product registrations in response to a Data Call-In for
neurotoxicity data.
This document reflects the Agency's final decision on the registration of chlorpyrifos
methyl. The Agency will finalize the decision for chlorpyrifos methyl tolerances after evaluating
the cumulative risk of the organophosphate class of pesticides. Because the Agency has not yet
completed the cumulative risk assessment for the organophosphates, this interim decision does
not fully address the reassessment of the existing food residue tolerances as required by section
408(q) of FQPA. When the Agency has completed the cumulative assessment, chlorpyrifos
methyl's reassessment decisions for the remaining import tolerances will be reassessed along
with the other organophosphate pesticides and a final determination will be made. Such an
incremental approach to the tolerance reassessment process is consistent with the Agency's goal
of transparency of the implementation of FQPA. By evaluating each organophosphate in turn
and identifying appropriate risk reduction measures, the Agency is addressing the risks from the
organophosphates in as timely a manner as possible.
This evaluation does not limit the Agency from making further FQPA determinations and
tolerance-related rulemakings that may be required on this pesticide or any other in the future. If
the Agency determines, as a result of this later implementation process, that any of the
determinations described in this Report on FQPA Tolerance Reassessment Progress and Risk
Management document are no longer appropriate, the Agency will pursue appropriate action,
including but not limited to, reconsideration of any portion of this document.
B. Summary of Phase 5 Comments and Revisions to the Risk Assessment
The availability of the revised risk assessment and supporting documents was announced
on April 28, 2000 in a Federal Register Notice (65 FR 83, Page 24954-24955). Interested
parties were provided a 60-day period to submit comments, including risk mitigation proposals.
Comments received during the 60-day public comment period were from Hansen Mueller,
Central Washington Grain Growers, Inc., OSU Pesticide Applicator Education Office, Gustafson
LLC-Western Region.
Gustafson and the grain industry submitted information on worker exposure. The grain
industry has requested that it be allowed to continue using chlorpyrifos methyl for pest control
until a suitable alternative is available. Some users stated that additional data requests from the
Agency are too costly. They also questioned why EPA rejected human data for chlorpyrifos-
methyl, while human data were used in malathion and pirimiphos-methyl risk assessments.
The Agency is aware of the importance of chlorpyrifos methyl to a segment of the grain
15D
-------
industry. This document describes the phase-out for this pesticide which the Agency believes
provides the opportunity for a reasonable transition away from chlorpyrifos methyl containing
products. The chlorpyrifos methyl usage information submitted by the registrant and others were
limited and generally consistent with the assumptions used in the Agency's assessment. The
Agency does not have a human study for chlorpyrifos methyl nor is the Agency aware of one.
The Agency is reviewing its policy regarding the use of human studies. The Agency's interim
policy is that we will not rely on any human testing for toxicity in making final decisions under
the FQPA until we have a robust policy in place that can ensure that any such studies meet the
highest scientific and ethical standards.
In addition to the comments received during the formal comment period, the Agency
received several hundred letters from the user community. These letters stress the importance of
chlorpyrifos methyl to a segment of the grain industry and that there are no registered
alternatives for direct grain treatment. They request the use of chlorpyrifos methyl be allowed
for a sufficient period of time to allow for the registration of a viable alternative pesticide
product. The Agency acknowledges the importance of this pesticide for a segment of the grain
industry. The phase-out period is intended to allow time to transition to alternative pest
management strategies.
C. Regulatory Position
1. FQPA Assessment
a. "Risk Cup" Determination
As part of the FQPA tolerance reassessment process, EPA assessed the risks associated
with this individual organophosphate. FQPA also requires the Agency to consider available
information on cumulative risk from substances sharing a common mechanism of toxicity, such
as the toxicity expressed by the organophosphates through a common biochemical interaction
with the cholinesterase enzyme. The Agency will evaluate the cumulative risk posed by the
entire class of organophosphates once the methodology is developed and the policy concerning
cumulative assessments is resolved.
EPA has determined that based on available data, risk from exposure to chlorpyrifos
methyl is within its own "risk cup." In other words, if chlorpyrifos methyl did not share a
common mechanism of toxicity with other chemicals, EPA would be able to conclude today that
the tolerances for chlorpyrifos methyl on stored grain meet the FQPA safety standards. In
reaching this determination, EPA has considered the available information on the special
sensitivity of infants and children, as well as chronic and acute food exposure. Because of the
use pattern for chlorpyrifos methyl (no residential uses and no drinking water exposure) an
aggregate assessment is not required.
The chlorpyrifos methyl tolerances remain in effect. However, in the near future, the
Agency intends to issue a proposed notice to revoke tolerances that will no longer be necessary
16D
-------
and reduce other tolerances. These modifications would take into account the time necessary for
legally treated grain to clear the channels-of-trade.
b. Tolerance Summary
Table 6 provides the current tolerance levels for chlorpyrifos methyl [O,O-Dimethyl-O-
(3,5,6-trichloro-2-pyridyl)phosphorothioate], as defined in 40 CFR §180.419, as well as
proposed changes based on EPA assessment. It also includes the tolerances that the Agency
will propose to revoke or reduce effective after the cancellation has occurred and legally treated
commodities have moved through the channels-of-trade.
When the cancellation of all chlorpyrifos methyl products has occurred, grain related
tolerances, except for wheat gluten will be revoked because they will no longer be needed. The
tolerance for the wheat will be modified to be for the wheat processed commodity bran and germ
at 20 ppm. The poultry and egg tolerances will be reduced by ten-fold or more. The remaining
milk, meat, and egg tolerances will be considered in the Agency's cumulative assessment of the
organophosphates. Therefore, these tolerance actions are interim pending the completion of the
cumulative assessment of the organophosphates.
17D
-------
Table 6: Tolerance Summary for Chlorpyrifos methyl
Commodity
Barley
grain
milling fractions (except flour)
Oats
grain
milling fractions (except flour)
Rice, grain
grain
milling fractions (except flour)
Sorghum
grain
milling fractions (except flour)
Wheat
bran
germ
Cattle, fat
Cattle, meat
Hogs, fat
Hogs, meat by products
Milk
Milk, fat
Poultry, fat
Poultry, meat byproducts
Poultry, meat
Eggs
Sheep, fat
Sheep, meat
Sheep, meat by-products
Tolerance Listed Under 40CFR §
180.419 (ppm)
6.0
90.0
6.0
130.0
6.0
30.0
6.0
90.0
30.0
30.0
0.5
0.5
0.5
0.5
0.05
1.25
0.5
0.5
0.5
0.1
0.5
0.5
0.5
Proposed Tolerance
(1999 Revised EPA Risk Assessment)
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
20.0 (processed commodity)
20.0 (processed commodity)
0.5
0.5
0.5
0.5
0.05
1.25
0.05
0.01
0.01
0.01
0.05
0.05
0.05
18D
-------
2. Endocrine Disrupter Effects
EPA is required to develop a screening program to determine whether certain substances
(including all pesticides and inerts) "may have an effect in humans that is similar to an effect
produced by a naturally occurring estrogen, or other such endocrine effects as the Administrator
may designate". Following recommendations of its Endocrine Disrupter Screening and Testing
Advisory Committee (EDSTAC), EPA determined that there was scientific basis for including,
as part of the program, the androgen and thyroid hormone systems, in addition to the estrogen
hormone system. EPA also adopted EDSTAC's recommendation that EPA include evaluations
of potential effects in wildlife. For pesticides, EPA will use FIFRA and, to the extent that effects
in wildlife may help determine whether a substance may have an effect in humans, FFDCA
authority to require the wildlife evaluations. As the science develops and resources allow,
screening of additional hormone systems may be added to the Endocrine Disrupter Screening
Program (EDSP).
When the appropriate screening and/or testing protocols being considered under the
EDSP have been developed, chlorpyrifos methyl may be subject to additional screening and/or
testing to better characterize effects related to endocrine disruption.
3. Label Modifications
The regulatory rationale for each risk mitigation measure is discussed below. Specific
labeling is in Table 7.
D. Regulatory Rationale
1. Dietary (Food) Risk Mitigation
Based on analyses of both acute and chronic dietary risk, the Agency has determined that
the risk estimates are below the Agency's level of concern; therefore, no mitigation measures are
necessary at this time.
2. Dietary (Water) Risk Mitigation
No drinking water exposure is anticipated from current uses; therefore, no mitigation is
necessary at this time.
3. Aggregate (Food + Water) Risk Mitigation
No mitigation for aggregate risk mitigation is necessary because no exposure is likely
from drinking water and there are no residential uses.
19D
-------
4. Occupational Risk Mitigation
The Agency is concerned about exposures resulting to handlers of dust and liquid
formulations of chlorpyrifos methyl. Levels of concern are exceeded for all but one scenario;
mixing and loading liquids for direct grain treatment using an automated system. The data
available to estimate exposures are limited or nonexistent for most scenarios, which increases
the concern of risk to workers. Of particular concern is the risks posed from applications
involving the dust formulations. Given the manner in which these formulations are applied (as
previously discussed), the opportunity for exposure is great, particularly through the inhalation
route. The registrants have, in response to the Agency's concerns, agreed to the voluntary
cancellation of all dust formulations with existing stocks permitted to be sold and distributed by
the registrant until March 30, 2001, and use until December 31, 2001.
The registrants have also agreed to measures that address the risks from handling liquid
formulations. Two uses will be allowed to continue until December 31, 2004, at which time
these uses will be canceled. The other uses of the liquid formulation will be voluntarily canceled
immediately. The two uses that will be allowed to continue are the empty bin treatment and the
direct treatment of stored grain with an automated system. To reduce exposure from treating
empty bins, the labeling will be amended to only allow treatment as a downward spray from
outside the bin (as opposed to the applicator spraying while inside the bin). By requiring the
applicator to be outside the bin during treatment and requiring the use of a respirator in addition
to the minimum PPE (long sleeved shirt, long pants, shoes, socks, chemical resistant gloves, and
eye protection), the Agency believes that exposures will be mitigated to the greatest extent
possible during the time this use is allowed to continue. The other use of the liquid that will be
allowed to continue until 2004 is the direct grain treatment in automated systems. This use does
not pose risks of concern to mixers and loaders, assuming use of minimum PPE. The last use
date for these two uses will be December 31, 2004.
V. What Registrants Need to Do
A. Generic Data Requirements
The data base supporting the continued registration of chlorpyrifos methyl has been
reviewed and there are significant data gaps. Chemical-specific data for handler and
postapplication exposure to insecticidal dust are required to complete the risk assessment, and
the following data gaps remain:
870.1100 Acute oral toxicity-RatD
870.1200 Acute dermal toxicity -RabbitD
870.1300 Acute inhalation study- RatD
870.2400 Primary ocular irritation-RabbitD
870.2500 Primary dermal irritation-RabbitD
870.2600 Dermal sensitization study- Guinea pigs D
870.6100 Delayed neurotoxicity study - HensD
20 D
-------
870.6200 Acute neurotoxicity study - RatD
870.3200 Subchronic dermal toxicity study - Rat or RabbitD
870.4100 Chronic toxicity-DogD
870.3700 Prenatal developmental study - RabbitD
870.3800 Two-generation reproduction study - RatD
870.6300 Developmental neurotoxicity study -RatD
870.7485 General metabolism-RatD
860.1500 Crop Field Trial- Aspirated Grain FractionD
A Data Call-In Notice (DCI) was recently sent to registrants of organophosphate
pesticides currently registered under FIFRA. DCI requirements included acute, subchronic, and
developmental neurotoxicity studies. In lieu of developing data to address the neurotoxicity
and other data gaps, the registrant has decided to voluntarily cancel registered uses. The
tolerances for import uses will remain effective, and will not be canceled. However, since these
tolerances have been reduced by 10-fold or more, they are not a concern because the levels are
non-detectable.
To address some of the data gaps and allow EPA to better characterize the risks
associated with chlorpyrifos methyl during the phase out period, the registrant has agreed to
provide EPA with an acute delayed neurotoxicity study in December 2001, and a two-generation
rat reproduction study in December, 2002.
B. Manufacturing Use Products
Labels changes are necessary to assure that end-use products can only be produced that
conform with the amendments listed in Table 7.
C. End-Use Products
Label changes are necessary to implement the measures outlined in Section IV above.
Specific language to implement these changes is detailed in Table 7.
D. Existing Stocks
The existing stocks provision will be determined after EPA has considered all comments
received on the chlorpyrifos methyl 6(f) notice, i.e., Notice of Receipt of Request for Voluntary
Cancellation. Barring substantive comments, EPA anticipates the dates would be as follows:
For dust formulations:
- Products would not be sold or distributed by registrants after March 31, 2001.
- All other persons would not sell, distribute or use after December 31, 2001.
For liquid formulations:
21D
-------
-Registrants would not sell or distribute products bearing old labeling after the stamped approval date
of new labels, i.e., labels that conform to the provisions of this document.
-Registrants could sell, and distribute products bearing labeling that conforms to Table 7 and other
provisions set forth in this document until December 31, 2003.
EPA is concerned that no use of chlorpyrifos methyl on grain takes place after December 31,
2004. Since it takes approximately four years for treated grain to cycle through the channels of trade,
the Agency intends to revoke most tolerances in 2008. Thus the use of chlorpyrifos methyl after
December 31, 2004 may result in adulterated commodities. In lieu of putting end use dates on the
label, registrants have agreed to notify their distributor of the last use date and the rationale for it.
E. Transition Strategy
E. Transition Strategy
EPA recognizes the importance of chlorpyrifos methyl to grain storage, particularly for
on-farm storage and the smaller country elevators. The Agency also understands that USDA policy is
to encourage growers to increase on-farm grain storage capacity. Because of the importance of
chlorpyrifos methyl to on-farm grain storage, a reasonable transition to alternative means of pest control
is provided as the voluntary cancellation proceeds. Researchers at land grant universities and the
USDA Agricultural Research Service are working to identify potential alternatives to chlorpyrifos
methyl. EPA is committed to continue work with USDA, registrants, and growers to assure that stored
grain is adequately protected from pest pressure. The Agency is working very closely with USDA to
assess pesticide and integrated management approaches currently being evaluated as potential
replacements for chlorpyrifos methyl. EPA and its stakeholders will expeditiously assess the viability of
any compounds identified as alternatives to chlorpyrifos methyl. In this vein, the Agency is evaluating
possible alternatives such as cyfluthrin and spinosad which may need to be used in combination with
other active ingredients.
Prior to the cancellation of chlorpyrifos methyl liquid products, the Agency in
consultation with USDA will assess progress being made toward developing alternatives. If it can be
determined that all reasonable efforts have been made towards developing a reduced risk alternative to
chlorpyrifos-methyl, and if a viable alternative is not found or available, the Agency will reevaluate the
phase-out, and determine if an extension of the phase out is appropriate. This reevaluation would occur
around the middle of 2003.
-------
F. Labeling
Table 7: Summary of Labeling Changes for Chlorpyrifos methyl
Description
Amended Labeling Language
Placement on Label
On all MUPs
Only for formulation into liquid insecticide products intended for the following uses: Empty grain
bin treatment; Direct grain treatments when applied through automated systems only.
This product may not be formulated into end use products after December, 31 2003.
The registrant will notify users of the last use date.
Directions for Use
One of these statements
may be added to a label to
allow reformulation of the
product for a specific use
or all additional uses
supported by a formulator
or user group
This product may be used to formulate products for specific use(s) not listed on the MP label if the
formulator, user group, or grower has complied with U.S. EPA submission requirements regarding
support of such use(s)."
"This product may be used to formulate products for any additional use(s) not listed on the MP label
if the formulator, user group, or grower has complied with U.S. EPA submission requirements
regarding support of such use(s)."
Directions for Use
Environmental Hazards
Statements based on the
RED and Agency Label
Policies
This product is toxic to fish, birds, and other wildlife. Do not discharge effluent containing this
product into lakes, streams, ponds, estuaries, oceans or other waters unless in accordance with the
requirements of a National Pollutant Discharge Elimination System (NPDES) permit and the
permitting authority has been notified in writing prior to discharge. Do not discharge effluent
containing this product to sewer systems without previously notifying the local sewage treatment
plant authority. For guidance contact your state Water Board or Regional Office of the EPA."
Precautionary Statements
23 D
-------
Table 7: Summary of Labeling Changes for Chlorpyrifos methyl
Description
Amended Labeling Language
Placement on Label
Handler PPE
Requirements1
"Personal Protective Equipment (PPE)
Mixers, Loaders, Applicators and other handlers systems: must wear:
long-sleeved shirt and long pants,
chemical-resistent gloves (such as2)
shoes plus socks
and protective eyewear3
In addition, applicators applying to empty grain bins must wear:
A NIOSH-approved dust mist filtering respirator with MSHA/NIOSH approval number prefix TC-
21C* or a NIOSH-approved respirator with any N4 R, P, or HE filter.
See Engineering Controls for additional requirements."
Precautionary Statements:
Hazards to Humans and
Domestic Animals
User Safety Requirements
"Follow manufacturer's instructions for cleaning/maintaining PPE. If no such instructions for
washables exist, use detergent and hot water. Keep and wash PPE separately from other laundry."
Precautionary Statements:
Hazards to Humans and
Domestic Animals
(immediately following the
PPE requirements)
Engineering Controls
"Engineering Controls
Handlers applying directly to grain must use an automated admixture system. The system must
apply the pesticide directly to the grain and transfer treated grain directly into stationary storage
facilities."
Precautionary Statements:
Hazards to Humans and
Domestic Animals
(immediately following PPE
and User Safety
Requirements.)
24 D
-------
Table 7: Summary of Labeling Changes for Chlorpyrifos methyl
Description
User Safety
Recommendation
Environmental Hazards
Statement
Application Restrictions
Entry Restrictions
Amended Labeling Language
"Users and persons in the treated area should avoid inhalation of treated grain dust."
"Users should wash hands before eating, drinking, chewing gum, using tobacco, or using the toilet."
"Users should remove clothing/PPE 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 the gloves
before removing. As soon as possible, wash thoroughly and change into clean clothing."
This pesticide is toxic to fish, birds, and other wildlife. Do not apply directly to water. Do not
contaminate water by cleaning of equipment for disposal of wastes. Do not discharge directly or
indirectly to surface water. Do not discharge effluent containing this product to sewer systems
without previously notifying the local sewage treatment plant authority.
"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."
"Empty grain bin treatment applications are only permitted from outside of the bin. Only downward
spray is permitted. All openings, except for the point of application, must be closed during
application. '
"This product may only be applied to empty grain bins using high pressure hand held or automated
spray equipment."
"Do not enter or allow others to enter until sprays have dried."
"Avoid contact with treated grain until liquid has dried."
Placement on Label
Precautionary Statements:
Hazards to Humans and
Domestic Animals
(immediately following
Engineering Controls)
Precautionary Statements
Directions for Use
Directions For Use
'PPE that is established on the basis of Acute Toxicity of the end-use product must be compared to the active ingredient PPE in this document. The more
protective PPE must be placed in the product labeling. For guidance on which PPE is considered more protective, see PR Notice 93-7.
25 D
-------
2 Registrant inserts correct glove material as per Supplement Three of PR Notice 93-7.
3 Usually, eye protection is not mentioned at this stage in the process; however, because this chemical is not subject to product reregistration nor is a product
specific DCI being issued, eye protection is included in this document.
4 If the product contains oil or bears instructions that will allow application with an oil-containing material, the "N" designation should be dropped.
Instructions in the "Amended Labeling Language" section appearing in quotations represent the exact language that should appear on the label.
26 D
-------
G. Procedure and Timing for Label Amendment
Registrants have submitted applications for amended registration on April 20, 2001.
Any additional amendments to the registration should include the following items: EPA
application form 8570-1 (filled in), five copies of each revised label, and a description on the
application, such as, "Responding to Interim Tolerance Reassessment Evaluation and Risk
Management Document." Registrants should send applications for amendment to the
appropriate following address:
Document Processing Desk (APPL)
Office of Pesticide Programs
Room 266A, Crystal Mall 2
1921 Jefferson Davis Highway
Arlington, VA 22202
Attn: Dennis McNeilly
Insecticide/Rodenticide Branch (7505C)
VI. Related Documents and How to Access Them
This report is supported by documents that are presently maintained in the OPP docket.
The OPP docket is located in Room 119, Crystal Mall #2, 1921 Jefferson Davis Highway,
Arlington, VA. It is open Monday through Friday, excluding legal holidays from 8:30 AM to
4:00 PM.
The docket initially contained the preliminary risk assessment and related documents as
of October 6, 1999. On December 5, 1999, the first public comment period closed. EPA then
considered comments, revised the risk assessment, and placed the revised risk assessment in the
docket on April 28, 2000. All documents, in hard copy form, may be viewed in the OPP docket
room or viewed or downloaded via the Internet (http://www.epa.gov/pesticides/op/).
27 D
-------
References:
1. D Gary Bangs (USEPA/OPPTS/OPP/HED), Chlorpyrifos methyl. Human Health Risk
Assessment. Chemical Number 059102. (DP Barcode D292273) 4/19/2000.
2. D Gary Bangs (USEPA/OPPTS/OPP/HED)Chlorpyrifos methyl-Revised HED
Occupational and Residential Exposure Chapter for the HED Risk Assessment.
Chemical Number 059102. DP Barcode (D265058) 04/17/2000.
3. D Sarah Levy (USEPA/OPPTS/OPP/HED), Revised Chlorpyrifos methyl: Residue
Chemistry Chapter of the RED, 11/01/1999.
4. D Sarah Levy (USEPA/OPPTS/OPP/HED), Chlorpyrifos methyl: Revised Acute and
Chronic Dietary Exposure Analyses, 10/28/1999).
5. D John Doherty USEPA/OPPTS/OPP/HED), Chlorpyrifos Methyl: Toxicology Section of
the RED Chapter. 04/17/2000.
28 D
-------
Appendix A: Use Patterns Allowed during Phase-out
Chlorpyrifos methyl
Application
Type of Equipment
Timing of
Application
Formulation
Maximum Rate
Restrictions/ Comments
Direct Grain Treatment
Automated
Admixture System
As grain enters
storage bin
4E (43% a.i.)
8 oz./3 gal of water
Avoid contact with treated grain until
liquid has dried
Empty Bin Treatment
High Pressure
Hand Held or
Automated System
To empty bin only
4E (43% a.i.)
8 oz./3 gal of water
Do not allow entry until dusts have dried
29 D
------- |