Pesticide Residues and Food Safety - ACS Publications - American

Chapter 29

The Need for Common Goals in Pesticide Management That Reflect the Consumers' General Interest John A. Moore

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Institute for Evaluating Health Risks, 100 Academy Drive, Irvine, CA 92715

A management plan is usually developed as a means to achieve some objective; its effectiveness is assessed against the achievement of the objective. It is generally held that pesticide use should be managed to prevent "unacceptable risk." However, the term is value laden and opinions as to its practical meaning or how it is to be realized are often in sharp disagreement. Inability to agree upon objectives dooms management to failure. Areas of ambiguity or conflict that must be addressed are found in statutes, hazard evaluation procedures and methods used to determine exposure. Examples of each will be presented and discussed. No governmental organization can effectively manage a pesticide program on behalf of the public if it does not have their confidence. It has been vividly demonstrated that the public confidence, particularly with respect to residues in foods, is often tenuous. To underscore this point I ask that you recall the cranberry scare associated with the pesticide Amitrole, concern over citrus fruit and stored grain that contained Ethylene Dibromide residues, and most recently Alar in apples. These crises of consumer confidence span a period of two decades with the pessimist opining that there is a decreasing duration of time between each event. The reasons which underlie the fragility of this trust are, I am sure, many and complex. However, there are several that are worthy of mention, with the most basic being that there has never been a clear understanding or acceptance within the general public as to the goals and conditions of pesticide use in the United States. What we have had instead is a circumstance where segments of society have developed their own perceptions of what those goals should be which, in turn, becomes their standard by which they judge performance.

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Tweedy et al.; Pesticide Residues and Food Safety ACS Symposium Series; American Chemical Society: Washington, DC, 1991.


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Unfortunately, these multiple sets of perceptions are frequently in conflict with each other. Who has a strong perception? The Environmental Protection Agency (EPA) certainly has an opinion as to what its job should be, and the U.S. Department of Agriculture traditionally also has firm, and somewhat differing, perspectives. Other strong points of view are held by pesticide producers, agricultural growers, processors, Congress has several viewpoints, food processors, food retailers, environmentalists, and consumer groups. For years the general public has been regularly bombarded by these points of view. These utterances are often replete with comments that are critical of the views held by others and the performance of EPA. Is it, therefore, so surprising that there is a concerned if not downright bewildered public that, in the view of many, over reacts? Despite the mixed messages it receives, the public consistently reaffirms one thing; that they care about the presence of pesticide residues in their food. Perhaps everybody would benefit in the future if, in the development of management strategies, they considered the consuming public as the major client. Let's be attentive to their concerns and perceptions. Let's develop a program that embodies their agenda as a primary component. In the development of such a strategy some of the fundamental tenets of pesticide policy need to be rethought, discussed, and restated. If there is to be a basic public acceptance of pesticide use in the United States, there must be dialog leading to a clear understanding of how the statutory term "unreasonable risk" is to be implemented. How that is defined will vary based on factors ranging from essentiality, groundwater concerns, and applicator exposure to the nature of effects on non-target biota. How the benefits of a food pesticide's use are calculated needs rethinking and better articulation. For example, the public response to Alar residues suggests that the benefit from a pesticide's use needs to more directly accrue to the person accepting the risk. Negligible risk has been put forth as a working concept for determining acceptable levels of pesticide residues in food. The myth that "zero residue" is a plausible concept needs to be discussed and finally laid to rest. From a pragmatic perspective the capabilities of analytical chemistry have forever shattered the belief that "pure" equates with no other chemical presence. As a toxicologist I believe the basic fact that it is dose that makes the poison and this fact provides a sound basis for utilizing a de minimis or negligible risk approach. The National Academy of Sciences report, "Regulating Pesticides in Food," outlined how this concept could be utilized in a manner that would be responsive to public health goals. The EPA announced a policy whereby negligible risk would be their preferred way to generally determine unacceptable residue levels for chemical carcinogens. However, there are four needs for this to be successfully implemented: 1) agree on the definition of the term; 2) define how it will be applied relative to benefit considerations; 3) reconcile the term within two federal statutes, the Federal Insecticide Fungicide and Rodenticide Act (FIFRA)


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and the Federal Food Drug and Cosmetic Act (FFDCA); 4) explain it to the public since it becomes their central point of reference when determining "safety" of their food. If negligible risk identifies the residue level that is not to be exceeded, how can the public be sure that, in fact, excess residues do not occur? What are the processes for monitoring food residues and just how effective are they? From my perspective the procedures and the data that are utilized to establish residue levels and then monitor the food supply resemble a patch work quilt. There are many pieces which originated from different places, had differing primary uses, and hopefully "fit together" to adequately serve a current purpose. If a goal is to respond to the concerns of the public, the nature of the process should be explained. As a prudent prerequisite there is a need to assess its effectiveness. Does it adequately serve the need for accurate risk estimation; is it a trusted sentinel for the presence of residues? There is a need to undertake a sound critical look at the entire process. When informing the public of the result, let's be sure to tell what the components are and how they fit together, what works well, what can be improved, and what needs to be replaced. A comprehensive evaluation of the process should include the following: Field residue data. Can the process be materially improved through the use of state as well as FDA data? Of prime interest are data from state regulatory agencies. Are they compatible from the perspective of analytical and sampling methodology? If so, will their use reduce the statistical uncertainty that currently exists due to a paucity of such data? In addition, are there data in the private sector which could be of value? What are the pros and cons of using them? Use of market basket surveys as an index of crop treated and level of residue. What should be the utility of the Food and Drug Administration's Market Basket Survey from a risk assessment perspective? EPA's Pesticide Program has been requiring Market Survey data on certain pesticides for the past several years. What is the utility of data of this sort in reducing uncertainty? Intuitively one seeks such data, and often is reassured by them; is there a sound basis for such a conclusion? Can such data be enhanced? How? In short, what are the best types of data and when should certain types be preferred? Do such data really provide certainty in a risk assessment? If certainty is not realized, what is preferred? Use of conversion factors to account for residue changes in food processing. For the vast majority of pesticides this information is only partially known or not known at all. What are the default assumptions that are used in such circumstances? What is their scientific underpin-


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ning? Can they be improved? Do such data exist (but not in regulatory hands) that could be made available? Will such data reduce the uncertainty? It is my suspicion that this whole area could be significantly improved through the use of real data (as opposed to default assumptions) or the utilization of scientifically sound algorithms.


A general review of the Dietary Residue Exposure System (DRES). It is

necessary to review the DRES, formerly the Tolerance Assessment System (TAS), developed and used by EPA, as to currency and statistical power of some of its derivations. In addition one needs to review, and make explicit, the decision rules for breaking down USDA dietary survey data into food components. Is there utility or benefit through the use of other data sources in certain circumstances? If there are other dietary surveys available, when is it appropriate or preferable to utilize differing data sets? A review of the generic assumptions used in any dietary risk assess-

ment These range from amount and frequency of dietary intake to summing residues across foodstuffs. One should also review when and how to integrate the data sets previously mentioned. Must one continue to use various default assumptions such as maximum legal tolerance and 100% of the crop treated? Does anyone seriously believe that because pesticide "x" is registered for use on corn for example, that an accurate risk estimation should assume every kernel of corn consumed for the rest of my life carries the highest residue? Can't we use real data? Do they exist? How can it be used for the public good? I doubt that the public good is served when the experts tell them that what I have just described is the proper way to estimate exposure and then, in the next breath, attempt to disassociate themselves from the ominous risk estimate because they don't believe it themselves. There are other instances where the use of default assumptions associated with legal tolerances in the calculation of risk estimates do not track with reality. Pesticide residue limits that are established for meat, milk, eggs, and poultry often can radically skew the exposure estimate. To convince the public that these traditional default assumptions are overestimates one must have better data. Establishing tolerances. Do the traditional procedures measure up to the needs of the 1990s? Using the legal tolerance as the benchmark for the calculation of risk estimates frequently results in marked overestimates. In such circumstances, is it the tolerance that is found wanting or the use to which it is being put? What is clear is that there are two needs: one is a numeric value that can discriminate whether a residue is legal or illegal for regulatory purposes; and the second is data that provide an accurate estimate of dietary exposure to pesticides.


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One must assess whether a single system can serve both needs and consider what is a reasoned alternative if the traditional methods are found wanting. Tolerances which were established many years ago basically accommodated to what many today would call a data point which is an outlier. Perhaps this practice should be revisited. Intuitively the average citizen knows that many pesticides can be toxic. Even if a level is in the "safe" (negligible risk) zone, why not add to the public's comfort through a policy of keeping exposure to a minimum. "Only use it when I have to and then, only at the lowest level needed to get the job done." What impact would the application of this philosophy have on the risk calculations? Is it more illusory than real? There is a need to have broad public understanding of goals which govern pesticide use in this country; particularly as it relates to the food they eat. In addition, the procedures that are used to judge the effectiveness of the program should be readily available, and described in terms of reference and in a time frame that is meaningful to the public. From a management standpoint the public as a consumer has a right to participate in setting a clear plan for the use of pesticides on food in this country. When such a plan is developed let's be sure that progress is measured against that plan's goal and not readily accept evaluations that merely reflect parochial points of view. RECEIVED August 21,1990


Pesticide Residues and Food Safety - ACS Publications - American

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