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Process for Reviewing Tolerance Decisions Based on the Use of Anticipated or Actual Residue Data

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EPA reviews pesticide tolerances that are based on anticipated or actual residue data. The information on this page may be useful to pesticide registrants, the environmental and public health community, growers, other pesticide regulators, or other stakeholders who want to understand better how EPA reviews and makes decisions regarding these tolerances. Basic information about pesticide tolerances.

EPA bases its tolerance risk assessments and decisions either on the assumption that residues will be present in food at the tolerance level, or on anticipated or actual residue data that more closely approximate residue levels that consumers may be exposed to in food.

By law, EPA is to require that data be provided to the Agency five years after it makes an initial tolerance decision based on actual or anticipated residue data. EPA must ensure that the data continue to support the safety standards in the law. After this first five year update, EPA may require new data, as appropriate to support the continuation of the tolerance. EPA collects updated information under the Food Quality Protection Act of 1996 (FQPA), which amended Section 408(b)(2)(E) of the Federal Food, Drug, and Cosmetic Act (FFDCA) Exit EPA disclaimer

EPA has a process for reviewing tolerance decisions that were based on the use of anticipated or actual residue data. The Agency uses this process to determine which data, if any, are needed to meet statutory requirements and to ensure that tolerances are safe.

FQPA required EPA to reassess all tolerances in effect as of August 3, 1996 (the date of enactment of the FQPA amendments) to ensure that they are supported by an up-to-date data base demonstrating safety. Thus, in most cases involving existing tolerances, the initial tolerance decision will be the tolerance reassessment decision required by FQPA.  At the time a tolerance review is completed, EPA will determine when the next review will be scheduled. Generally, subsequent reviews will be done as part of Registration Review. However, EPA may require data and conduct reviews at any time, outside of the Registration Review cycle, if the Agency believes that the Agency’s review conclusions could reasonably change as a result of changed circumstances over time.

Below is a brief discussion of the primary types of anticipated or actual residue data used by EPA, followed by a description of the review process itself.

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Types of Anticipated or Actual Residue Data

The types of data used for the initial tolerance decision affect whether changes in use practices by growers under an existing pesticide registration have the potential to raise residue levels in food above the anticipated or actual residue levels used in the initial assessment.

If the initial tolerance decision relied on anticipated residue levels from magnitude of residue studies, such as field trial, processing, and meat/milk studies, residue levels in food are generally unlikely to exceed the anticipated residue level in future years.

If the initial tolerance decision relied on actual residue data from monitoring studies and surveillance programs, however, changes in agricultural and food production practices could result in increases in residues that may require a change in EPA's initial tolerance decision.

EPA may rely on the following types of anticipated and actual residue data in making tolerance decisions.

Magnitude of Residue Data

Magnitude of Residue studies are generally conducted using the maximum amount of pesticide legally permitted to be applied according to the EPA-approved label and registration. In some circumstances, for scientific reasons, (for example, if the amount of residue expected to result from legal use is lower that the limit of detection of methods used to analyze food for the pesticide residue), studies are designed to exaggerate maximum label directed amounts. Generally, when these types of study data are used in making tolerance decisions, the next scheduled review will occur as part of the Registration Review Program.  

The most commonly used Magnitude of Residue data used in dietary risk assessments are data from crop field trial residue studies. The goal of field trial studies is to determine the maximum residue likely to result in or on food crops from legal use of the pesticide. Accordingly, crop field trial residue studies are conducted in several locations that are representative of the variety of growing conditions in areas where the crop is grown, and reflect maximum use rates, maximum number of applications, and minimum duration after application that the crop may be harvested (pre-harvest intervals (PHIs)), as defined by the pesticide registration and label.

Residue samples are obtained immediately upon harvest of the food commodity. Residues on food as consumed generally are lower than the values measured in crop field trial residue studies because of variations in use practices (either not using the pesticide at all or using it in a manner not likely to produce maximum residues), degradation of residues between time of harvest and consumption, and cooking and processing practices that break down residues.

Residue levels may change as use practices change. For example, growers may increase or decrease the amount of pesticide applied or the frequency of application – within the range allowed on the pesticide label – as pest pressures change. Such changes would not affect the residue levels measured in crop field trial residue studies, because such studies are designed to maximize residue levels, as described above. If the use patterns permitted by the pesticide registration and label are amended, however, (e.g., changes in pre-harvest intervals or application rates), crop field trials may become outdated. In general, EPA requires new field trials and conducts a revised risk assessment before granting registration amendments that might increase exposure to residues in food, to ensure that tolerances continue to meet food safety standards.

In instances where EPA has relied upon crop field trial residue studies in estimating anticipated residues, EPA believes that requiring registrants to submit new data bearing on anticipated residues would be of negligible scientific value in the absence of changes in the registration that might increase residue levels. Requiring the submission of new crop field trial residue studies would mean requiring registrants to duplicate existing valid and approved studies. Requiring the submission of monitoring data in such cases also would be of little value because monitoring data would only provide information on how much lower actual residue levels are, compared to the maximum values obtained through the standard crop field trial designed to produce maximum residues.

Food processing practices do not change significantly from year to year, and therefore EPA’s requirements for food processing studies change infrequently. Like field trial studies, processing studies are conducted so as to maximize the amount of residues permitted by the EPA-approved pesticide label, based on maximum use rates, minimum PHIs, etc. Unless processing practices and/or EPA-processing study guidelines have changed since the initial tolerance decision, EPA does not anticipate requiring additional processing data to verify its previous safety finding.

EPA requires animal feeding/meat and milk studies to support tolerance decisions when there may be residues in meat and milk resulting from pesticides used on animal feed crops, or when a pesticide may be used directly on the animal (e.g., to control ectoparasites). Like field trial and food processing studies, these studies are also designed to maximize the amount of residues resulting from maximum use of the pesticide according to its EPA-approved label. In the absence of changes in production practices, the studies used in previous tolerance decisions would continue to represent maximum residue levels. If new practices are adopted, EPA would need to evaluate whether new animal studies are warranted. If the pesticide registration is amended in such a way that pesticide residues would increase, a new study would be required as part of the registration amendment process.

Monitoring Data

Monitoring data reflect actual use patterns and may be expected to vary over time, depending on a number of factors, including the percent of the crop that is treated, application methods and rates, frequency of application, and timing of the last application prior to harvest. While food producers may not legally increase application rates or frequencies, or reduce pre-harvest intervals (PHIs), beyond what is specified on the EPA-approved label, they may use less of the pesticide, and the actual PHI may be longer than permitted by the label. Actual use of a product in a given season can be affected by many factors including pest pressure, product cost, availability of effective alternative pest control products and techniques, and development of pest resistance. As a result, (unlike data from controlled field trial, animal feeding, and processing studies), residues based on monitoring data may be expected to change over time, as practices change.

If EPA has relied upon monitoring data in its initial tolerance decision, some reanalysis of the initial tolerance decision and safety finding is necessary. If valid, current monitoring data are available, for example from the Pesticide Data Program or FDA surveillance programs, these data will be used by EPA to re-estimate residues. To the extent that data on the percent of a crop that is treated with a pesticide were used originally to inform the assignment of values to “non detects” within the monitoring data base, EPA will seek out new percent crop treated data to inform the new residue estimates. If valid, current data are not available, EPA will conduct an assessment to determine the likelihood that use patterns have changed in ways that would increase the frequency of detections or levels of residues present in food, compared to the data and information used to support the initial tolerance decision. If it is likely that use patterns have changed in a manner that would increase residues, the Agency will issue a data call-in (DCI) requiring new monitoring data, unless analysis of other available data and information demonstrates that safety standards are met.

Percent Crop Treated (PCT)

Percent crop treated (PCT) data are covered by a separate provision of the law. They are reviewed separately from anticipated or actual residue data and are subject to "periodic review" [see FFDCA Section 408(b)(2)(F)] Exit EPA disclaimer . EPA does not routinely consider PCT in making a determination regarding the need for additional data in connection with tolerance reviews under the anticipated and actual residue provisions of FFDCA 408 (b)(2)(E), as described here. Overall, EPA intends to address PCT issues through the Registration Review program.

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Review Process

Download diagram of review process
(PDF 1pp, 19K, About PDF) This is a graphical representation of the  process described on this page. It depicts the same content written here.



The anticipated/actual residue data review process is a tiered approach designed to focus EPA resources on tolerance decisions where new information could alter EPA’s initial tolerance decisions and safety findings. The Agency begins by reviewing all of the active ingredients scheduled for review within a given year, and assembling a list of all of the active ingredients for which initial tolerance decisions might have involved the use of anticipated or actual residue data for one or more commodities. Unless EPA is certain that none of the previous tolerance decisions were based on anticipated or actual residue data, the active ingredient will be included in the list for screening analysis. The Agency reviews the underlying assessments to verify which data were used to support the initial tolerance decisions for each active ingredient on the list. Below is a step-by-step discussion of the questions and considerations that EPA reviews in conducting its analyses. Attachment I (PDF) (1 pg, 19K, About PDF, ) is a chart summarizing the overall process.

1. What type(s) of data were used to support the initial tolerance decision?

2. If monitoring data were used to support the initial tolerance decision, do valid current monitoring data exist?

3. Is there an increase in either the frequency of detections or the actual residue levels OR would changes in use patterns or the amount used be expected to increase residue levels?

4. If the anticipated or actual residue levels have increased since the initial decision, is a new risk assessment needed?

5. If a new risk assessment is needed, does the assessment indicate a potential risk of concern?

6. What type(s) of data were used in the new risk assessment?

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