Residue Reviews

The full scope and significance of the efforts exerted by the individual states (U.S.A.) in the regulatory and research areas involving pesticide residues are probably not fully appreciated. However, the combined accomplishments of the individual states, both in the regulatory and research areas, have a very considerable impact on the agricultural growers and consumers of this country. Of course, there is vast difference between individual states with respect to their funding to support regulatory and/or research efforts in this field. Some states, for varying reasons, invest very few resources or effort in either the regulatory or the research areas involving pesticide residues. These states usually depend on the federal regulatory agencies and other states for direct or indirect support. On the other end of the spectrum, certain states with large, diverse agricultural resources to protect, invest significant resources in comprehensive regulatory and research programs involving pesticide residues. Florida should be considered in this latter category of states because of its very diverse and large fruit and vegetable crop industry and a climate that requires a high degree of pest control to protect its crops. Consequently, Florida will be used as an example of one state’s contribution to the pesticide residue field. Because of Florida’s comprehensive regulatory coverage of its fruit and vegetable crops, with respect to adherence to established tolerances for pesticide residues, the Food and Drug Administration restricts its regulatory activities in Florida to a very limited surveillance program. In Florida, the purpose of the pesticide residue program of the Florida Department of Agriculture and Consumer Services is not only regulatory, but is also designed to aid and advise Florida growers wherever possible in avoiding excessive pesticide residues on their marketable crops.

If pesticide residues are of concern in developed countries, there is no reason why they should not be of concern to developing countries as well. Of course, the concern is expected to differ in orientation as a result of differences in value systems. Thus, while developed countries can now afford to shift attention to environmental problems, our attention in developing countries is still in the food production aspect. This is because developing countries are generally in a state of chronic nutritional deficiency and so national priorities must be marshalled to meet this more pressing need. Usage of pesticides is also low in developing countries; it has been estimated that the United States, Europe, and Japan are responsible for about 82% of the total world pesticide consumption, not including China, the Philippines, and other developing countries taking care of the remaining 18%. Climatic differences may, in fact, mitigate against our being so involved with pesticides in the environment although the paucity of data and the complexity of the food web in the tropical environment is a cause for concern.

From the time a pesticide is applied until its residues are eventually measured, some 10 factors are operative, which determine whether the result of an analysis will be “representative” or not (FREHSE 1977):

Widespread use of pesticides¹ has greatly benefited mankind by increasing food and fiber production, controlling the vectors of serious human and animal diseases, protecting structures from damage, and controlling weeds, etc. However, we have largely overlooked the problem of environmental pollution caused by the indiscriminate use of pesticides. The biological activity of pesticides is not only restricted to the target organisms but extends to nontarget organisms as well. Among the non-target organisms, microorganisms are of major concern because they are more responsible to their environment as they are involved in many basic ecological processes such as biogeochemical cycling, decomposition processes, energy production, energy transformation through trophic levels, and numerous microbe-microbe, microbe-plant, and microbe-animal inter-actions.

The benefits of pesticides have become so much a part of agricultural economics that world-wide food and fiber production would be drastically reduced without some form of chemical assistance and protection.

This discussion is intended to set forth certain features of current outlook concerning risk and, to some extent, benefits. These are only partially matters of science, and scientists or users of science should be very much aware of this: not to change it, necessarily, but better to understand, and to assess, scientific contributions or participations of scientists in risk/ benefit determinations.

The metabolism of both the natural and synthetic pyrethroids¹ is a complicated and overpowering subject. In this report a historical review of the literature is presented in the hope that the facts which comprise the current wealth of information can be presented individually, roughly in order of their discovery. It is not intended to cover all the literature since reviews of specific aspects are readily available but it is intended to mention all the salient points. It is also hoped that some interest will arise from seeing how progress in these metabolism studies depended on advances in other areas and how the subject of these studies has changed from insects to mammals and plants as fears about human and environmental safety have increased. We now have the seemingly paradoxical situation in which metabolism studies of insecticides are undertaken on almost anything other than insects.