Skip to Content


Pesticides; Policy Issues Related to the Food Quality Protection Act

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


Environmental Protection Agency (EPA).


Notice of availability.


EPA is announcing the availability of the revised version of the pesticide science policy document entitled “Choosing a Percentile of Acute Dietary Exposure as a Threshold of Regulatory Concern.” This notice is the fifteenth in a series concerning science policy documents related to Food Quality Protection Act and developed through the Tolerance Reassessment Advisory Committee.

Start Further Info


Kathleen Martin, Environmental Protection Agency (7509C), 401 M St., SW., Washington, DC 20460; telephone number: (703) 308-2857; fax number: (703) 305-5147; e-mail address:

End Further Info End Preamble Start Supplemental Information


I. General Information

A. Does this Action Apply to Me?

You may be potentially affected by this action if you manufacture or formulate pesticides. Potentially affected categories and entities may include, but are not limited to:

CategoriesNAICSExamples of potentially affected entities
Pesticide producers32532Pesticide manufacturers Pesticide formulators

This listing is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be affected by this action. Other types of entities not listed could also be affected. The North American Industrial Classification System (NAICS) codes Start Printed Page 15331have been provided to assist you and others in determining whether or not this action affects certain entities. If you have any questions regarding the applicability of this action to a particular entity, consult the person listed under FOR FURTHER INFORMATION CONTACT.

B. How Can I Get Additional Information, Including Copies of This Document or Other Related Documents?

1. Electronically. You may obtain electronic copies of this document, the revised science policy document, and certain other related documents that might be available from the Office of Pesticide Programs' Home Page at​pesticides/​. On the Office of Pesticide Programs' Home Page select “FQPA” and then look up the entry for this document under “Science Policies.” You can also go directly to the listings at the EPA Home page at On the Home Page select “Laws and Regulations” and then look up the entry to this document under “Federal Register--Environmental Documents.” You can go directly to the Federal Register listings at​fedrgstr/​. The document entitled “Responses to Public Comments on the Office of Pesticide Program's Draft Science Policy Document” is available on EPA's Home Page with the Federal Register document at the above web site.

2. Fax on demand. You may request a faxed copy of the revised science policy document, as well as supporting information, by using a faxphone to call (202) 401-0527. Select item 6046 for the document entitled “Choosing a Percentile of Acute Dietary Exposure as a Threshold of Regulatory Concern.” You may also follow the automated menu.

3. In person. The Agency has established an official record for this action under docket control number OPP-00593A. In addition, the documents referenced in the framework notice, which published in the Federal Register on October 29, 1998 (63 FR 58038) (FRL-6041-5) have also been inserted in the docket under docket control number OPP-00557. The official record consists of the documents specifically referenced in this action, and other information related to this action, including any information claimed as Confidential Business Information (CBI). This official record includes the documents that are physically located in the docket, as well as the documents that are referenced in those documents. The public version of the official record does not include any information claimed as CBI. The public version of the official record, which includes printed, paper versions of any electronic comments submitted during an applicable comment period is available for inspection in the Public Information and Records Integrity Branch (PIRIB), Rm. 119, Crystal Mall #2, 1921 Jefferson Davis Highway, Arlington, VA, from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal holidays. The PIRIB telephone number is (703) 305-5805.

II. Background for the Tolerance Reassessment Advisory Committee (TRAC)

On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was signed into law. Effective upon signature, the FQPA significantly amended the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug, and Cosmetic Act (FFDCA). Among other changes, FQPA established a stringent health-based standard (“a reasonable certainty of no harm”) for pesticide residues in foods to assure protection from unacceptable pesticide exposure; provided heightened health protections for infants and children from pesticide risks; required expedited review of new, safer pesticides; created incentives for the development and maintenance of effective crop protection tools for farmers; required reassessment of existing tolerances over a 10-year period; and required periodic re-evaluation of pesticide registrations and tolerances to ensure that scientific data supporting pesticide registrations will remain up-to-date in the future.

Subsequently, the Agency established the Food Safety Advisory Committee (FSAC) as a subcommittee of the National Advisory Council for Environmental Policy and Technology (NACEPT) to assist in soliciting input from stakeholders and to provide input to EPA on some of the broad policy choices facing the Agency and on strategic direction for the Office of Pesticide Programs. The Agency has used the interim approaches developed through discussions with FSAC to make regulatory decisions that met FQPA's standard, but that could be revisited if additional information became available or as the science evolved. As EPA's approach to implementing the scientific provisions of FQPA has evolved, the Agency has sought independent review and public participation, often through presentation of many of the science policy issues to the FIFRA Scientific Advisory Panel (SAP), a group of independent, outside experts who provide peer review and scientific advice to the Office of Pesticide Programs (OPP).

In addition, as directed by Vice President Albert Gore, EPA has been working with the U.S. Department of Agriculture (USDA) and another subcommittee of NACEPT, the TRAC, chaired by the EPA Deputy Administrator and the USDA Deputy Secretary, to address FQPA issues and implementation. TRAC comprises more than 50 representatives of affected user, producer, consumer, public health, environmental, states and other interested groups. The TRAC has met seven times as a full committee from May 27, 1998 through October 21, 1999.

The Agency has been working with the TRAC to ensure that its science policies, risk assessments of individual pesticides, and process for decision making are transparent and open to public participation. An important product of these consultations with TRAC is the development of a framework for addressing key science policy issues. The Agency decided that the FQPA implementation process and related policies would benefit from initiating notice and comment on the major science policy issues.

The TRAC identified nine science policy issue areas it believes were key to implementation of FQPA and tolerance reassessment. The framework calls for EPA to provide one or more documents for comment on each of the nine issues by announcing their availability in the Federal Register. In accordance with the framework described in a separate notice published in the Federal Register of October 29, 1998 (63 FR 58038), EPA is announcing through the Federal Register the availability of a series of draft documents concerning nine science policy issues identified by the TRAC related to the implementation of FQPA. After receiving and reviewing comments from the public and others, EPA is also issuing revised science policy documents which reflect changes made in response to comments. In addition to comments received in response to these Federal Register notices, EPA will consider comments received during the TRAC meetings. Each of these issues is evolving and in a different stage of refinement. Accordingly, as the issues are further refined by EPA in consultation with USDA and others, they may also be presented to the SAP.

III. Summary of Revised Science Policy Guidance Document

EPA is responsible for regulating the nature and amount of pesticide residues in food under FFDCA. FFDCA section 408 authorizes EPA to set a tolerance or Start Printed Page 15332an exemption from the requirement of a tolerance if the Agency determines that the residues would be “safe.” The Agency performs various types of risk assessments to evaluate the safety of pesticides in food, including analyses to determine the nature and the amounts of pesticides that people might be exposed to over a single day. This science policy document discusses how EPA generally applies the statutory safety standard to acute dietary risk assessments as to pesticide residues in foods.

The Environmental Protection Agency's Office of Pesticide Programs previously announced that, on an interim basis, it intended to use the 99.9th percentile of the distribution of estimated acute dietary food exposures for calculating a threshold of concern when probabilistic assessment techniques are used to model the distribution. OPP stated that it would compare this percentile of estimated exposure to the Population Adjusted Dose (PAD), a value that reflects an amount of a pesticide to which a person may safely be exposed in one day. The Agency published a notice in the Federal Register on April 7, 1999 (64 FR 16962) (FRL-6074-7), citing the availability of an interim policy and requested public comment so that the views of all interested parties would be considered (US EPA, 1999a).

Based in part on the comments received, this science policy document was revised and is now being issued in its revised format. This revised document explains OPP's policy and details some of the various concerns that have been raised, additional associated public health-related issues, as well as OPP's plans for further evaluation and implementation. This policy has broad applicability to many pesticides and a potentially significant impact on the assessment of these pesticides.

OPP's current approach with respect to assessing and regulating the food uses of pesticides, when using a probabilistic method of estimating acute dietary exposure, is as follows:

If the 99.9th percentile of acute exposure from food, as estimated by probabilistic (e.g., Monte Carlo) analysis, is equal to or less than the acute Population Adjusted Dose (aPAD) for the pesticide, then OPP would generally consider its threshold of concern in applying that the safety standard of FFDCA section 408(B)(2)(A) not to be exceeded with respect to acute risk from food. However, if the analysis indicates that estimated exposure at the 99.9th percentile exceeds the PAD, OPP would generally conduct a sensitivity analysis to determine to what extent the estimated exposures at the high-end percentiles may be affected by unusually high food consumption or residue values. To the extent that one or a few values from the input data sets seem to “drive” the exposure estimates at the high end of exposure, OPP would consider whether these values are representative and should be used as the primary basis for regulatory decision making. In either scenario, EPA would consider submissions by interested parties that question the appropriateness of the use of the 99.9th percentile in calculating the threshold of concern for the particular risk assessment in question or question its use generally.

It is important to note here that the above position refers to the 99.9th percentile of exposure and not consumption. The 99.9th percentile of exposure represents the joining of each individual's consumption data set with randomly selected residue values from the residue data set. The consumption values associated with the 99.9th percentile of exposure do not necessarily represent the 99.9th percentile of consumption since it is both the selected consumption value and residue concentration which is responsible for determining exposure.

At this time, OPP's current policy is used only with daily exposures to a single chemical through the food pathway only. Estimates of exposure through drinking water and residential uses are not sufficiently developed to warrant inclusion in a probabilistic assessment. Establishing the threshold of concern for the food pathway using the 99.9th percentile of exposure is considered to be a “first step” toward regulation of exposures on an aggregate, and then cumulative, basis.

OPP recognizes that different types of risk assessments will generally be needed for aggregate and cumulative evaluations and that these assessments might also be associated with different regulatory thresholds. Although OPP is moving toward regulating on the basis of probabilistic aggregate and cumulative exposure assessments, a decision has not yet been made regarding how the appropriate threshold of concern should be calculated for these types of assessments. When exposures through drinking water and residential uses are sufficiently refined to be incorporated into probabilistic evaluations, they will be aggregated and assessed, and may use a different population percentile.

Section I of this provides an overview of OPP's present practice for acute dietary risk assessment for residues in food. It describes the statutory, regulatory, and policy framework for this policy, as well as prior reviews and comments. In addition, this section provides background information on dietary risk assessment in general and explains how the previous system (DRES—Dietary Risk Evaluation System) and the current system (DEEM—Dietary Exposure Evaluation Model) work, as well as what input data sources are used and how.

Section II addresses some of the specific issues and concerns raised about using exposures at the estimated 99.9th percentile in calculating the threshold of concern. One issue is whether the nature of the data bases available (i.e., robustness, adequacy, etc.) should preclude the use of the estimated 99.9th percentile for regulatory purposes since some consider the uncertainties associated with this population percentile to be too great. Examples of data used are USDA's food consumption survey data, registrant crop field trials, USDA Pesticide Data Program (PDP) data, FDA monitoring data, market basket surveys, etc. Other issues include the treatment of data “outliers,” representativeness and adequacy of the data bases, and the impact of Agency default values on exposure estimates. Concerns, therefore, exist about whether the estimates of the 99.9th percentile of exposure are sufficiently representative of actual exposure to be meaningful. This science policy document summarizes these concerns and how OPP has addressed them.

Section III addresses the issue of protectiveness of the estimated 99.9th percentile of exposure with respect to the general public health. One view is that using the estimated 99.9th percentile of exposure is insufficiently conservative because very large numbers of people could be exposed every day to pesticide intakes which are estimated to exceed the Agency's “level of concern.” This section also explores the contrary view that the policy is over-protective because of the conservative assumptions used in the estimation methods and the retention of potentially unrepresentative values in the data base. The section discusses as well the view that, whether it over-estimates or under-estimates actual exposure, the estimated 99.9th percentile of exposure is simply too uncertain to be used in risk management decisions.

Section III also explains that OPP weighs a number of factors in considering which percentile to use: The size of the exposed population and the proportion that might receive daily doses above the benchmark of safety, Start Printed Page 15333the aPAD; the level of confidence OPP has in its exposure estimates; and the extent to which such estimates may overstate potential exposure because they incorporate conservative assumptions or rely on atypical and unrealistic data. Further, to the extent understood, OPP considers by how much individual exposures would be estimated to exceed the aPAD.

Section IV briefly addresses the issues associated with exploratory analysis conducted by OPP with the DEEM software and the 99.9th percentile issue. Further details and specifics of this analysis are provided in the associated response to public comments.

Section V provides a list of the documents referenced in this science policy document.

The Appendix, entitled “Primer on Interpretation of Exposure Distribution Curves,” is a “plain English” guide to Monte Carlo analysis and interpretation of its results.

IV. Issues Raised in Comments

EPA published a draft version of the document described in Unit III. under SUPPLEMENTARY INFORMATION on April 7, 1999 (64 FR 16962) and comments were filed in docket control number OPP-00593. The public comment period ended on June 7, 1999. The Agency received comments from numerous different organizations. All comments were considered by the Agency in revising the document.

Many of the comments were similar in content, and pertained to general issues concerning the proposed policy or specific sections within the draft document. The comments addressed a broad range of issues and, in many instances, provided no general consensus. The Agency grouped the comments according to the nature of the comment and the issue or section of the document which they addressed. For the substantive comments that follow, contrasting opinions are presented, along with EPA's response. The full text of the Agency's response to the comments is available as described in Units I.B.1. and I.B.2. under SUPPLEMENTARY INFORMATION.

V. Policies Not Rules

The revised science policy document discussed in this notice is intended to provide guidance to EPA personnel and decision-makers, and to the public. As a guidance document and not a rule, the policy in this guidance is not binding on either EPA or any outside parties. Although this guidance provides a starting point for EPA risk assessments, EPA will depart from its policy where the facts or circumstances warrant. In such cases, EPA will explain why a different course was taken. Similarly, outside parties remain free to assert that a policy is not appropriate for a specific pesticide or that the circumstances surrounding a specific risk assessment demonstrate that a policy should be abandoned.

Start List of Subjects

List of Subjects

  • Environmental protection
  • Administrative practice and procedure
  • Agricultural commodities
  • Pesticides and pests
End List of Subjects Start Signature

Dated: March 16, 2000

Susan H. Wayland,

Acting Assistant Administrator for Prevention, Pesticides and Toxic Substances.

End Signature End Supplemental Information

[FR Doc. 00-7126 Filed 3-21-00; 8:45 am]