PREDICTING EFFECTS OF PESTICIDES ON NON-TARGET ORGANISMS

Abstract

Prior to World War II, pesticides were non-persistent, usually derived from natural organics, such as pyrethrins and nicotine sulfate. Today a wide range of organic and inorganic pesticides-- fungicides, insecticides, rodenticides, herbicides, fumigants, and bactericides--is produced by over 800 companies. These pes ticides are applied to farm, forest, pond, marsh, rangeland, gar den and lawn. Pesticide residues are found in every major river system in the country. The major pesticidal concern in the United States has been in the area of human safety as related to pesticide residues in foods. Only within the past decade has serious attention been focused on the effects of pesticides on wildlife and other ele ments of the environment. Elements of the environment, not in tended to be controlled by a given pesticide application, are referred to as non-target organisms. The Environmental Protection Agency (EPA) has the responsi bility of registering pesticides under the Federal Insecticide, Fungicide, Rodenticide Act (FIFRA).1 The Administrator of the agency registers a pesticide after he determines that, when con sidered with restrictions, it will perform its intended effect on the environment and when used in accordance with widespread and commonly recognized practices it will not generally cause unreasonable adverse effects on the environment. The term "unreasonable adverse effect" is defined in the Act to require a balancing of the risks and benefits which would accrue through the use of a pesticide, including economic, social, and environ mental costs. Trends indicate that the use of pesticides will continue to increase in the immediate future. The present and future hazards associated with the use of pesticides are real. Determination of the probable impact of pesticides must include careful assessments of the factors contributing to environmental hazard. Questions are often raised when biologists attempt to extrapolate from labo ratory studies, but a prediction of the consequences or hazards associated with the use of a pesticide must be made in advance of the introduction into the environment. Predicting effects of pesticides on non-target organisms is difficult. This paper will consider the important factors and data bases necessary for predicting the effects of pesticides on non target species. A model for predicting effects will be con structed after first determining the significant factors involved in the fate and movement of pesticides in the environment and the toxicological characteristics and impact of pesticides on the various components of the environment. Under FIFRA, the laboratory data used to determine the ecological impact of pesti cides are required to be furnished by the company desiring to register. Consequently, the model must utilize such data. In this paper the factors that influence the fate and move ment of pesticides in the environment will be determined. Data on the major agricultural crops, including acreage and geographi cal distribution, will provide the mechanisms for estimating po tential pesticide usage and distribution. Toxicological studies that are relevant to making extrapolations and predictions will be identified, including appropriate laboratory indicator or ganisms. These will include acute, subacute, chronic, and repro duction studies with birds, mammals, fish, and invertebrates. The limitations to extrapolation from laboratory studies to field situations will be identified and alternative methods for evaluation under specific circumstances will be suggested. This model will provide information on the expected environ mental behavior of a pesticide. We can no longer afford to learn about adverse effects of a new pesticide through a decade of use.