Field evaluation of the EPA (Kenaga) nomogram, a method for estimating wildlife exposure to pesticide residues on plants
1996
Pfleeger, T.G. | Fong, A. | Hayes, R. | Ratsch, H. | Wickliff, C.
The Kenaga nomogram was developed by the U.S. Environmental Protection Agency (EPA) in the mid 1970s and has since been used prior to the registration of a pesticide to estimate the maximum potential pesticide residue level on plant material in the food chain of wildlife. The objective of this study was to evaluate the nomogram using field data. Six pesticides representing a variety of pesticide classes were applied to 15 plant species. Five of the six nomogram categories were tested with plant parts representing differences in surface morphology (i.e., glabrous vs. pubescent leaves). The sixth category was a mixed-grass community seeded with three grass species. Pesticide residue levels were determined the day of application and up to 32 d afterward. While the linear nomogram model does not represent the data as well as other models, relatively few data points (10%) collected on the day of pesticide application exceeded the nomogram predictions. The one systemic pesticide tested had degradation rates similar to nonsystemic pesticides in most categories. Present nomogram categories were significantly different from each other in most cases. However, the forage category should be combined with the leaves and leafy-crop category and have higher estimated residue levels than the Kenaga nomogram. A considerable amount of variation occurs in the level of pesticide residue on plant materials even under controlled experimental conditions and therefore nomogram values should be used as an estimate only until actual field residue data are available. The nomogram, with modifications, appears to be a reasonable regulatory device if careful thought is given in selecting the plant category for making residue estimates.
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