ISSN:
1432-0703
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
,
Medicine
Notes:
Abstract The U. S. Environmental Protection Agency uses a simple exposure nomogram to make preliminary assessments of the pesticide residues concentrations on foods of terrestrial wildlife. This study was conducted to measure the spatial and temporal distribution of the organophosphorus insecticide azinphos-methyl (Guthion® 2S) in a dense alfalfa crop to evaluate the assumptions used in this nomogram and to determine the influences of application rate and spatial distribution of residues on the potential dietary exposure to herbivores. Concentrations of azinphos-methyl were measured on spray cards, soil, and alfalfa plants (top 15 cm and bottom 15 cm) on plots treated at 0, 0.77, 1.55, 3.11, and 4.67 kg active ingredient/ha (4 enclosures/treatment) at 2 h and 2, 6, 14 and 28 days after application. Although the concentrations measured on spray cards were very close to predicted, the concentrations on alfalfa canopy vegetation were higher than expected from the nomogram and increased at a faster rate with increasing application rate than expected. Concentrations were 1.5–2.4 times higher in the alfalfa canopy than on alfalfa near soil level. Variability among alfalfa samples within treatments was high, with part of the variation in canopy samples explained by the distance to the end of the spray boom. Only 16–32% of pesticide reached the soil surface. The calculated half-life of azinophos-methyl was 2.5–4.5 days on vegetation and 19.3 days on soil. Dietary exposure to small herbivores would be expected to exceed nomogram predictions, but be highly variable for individuals due to the patchy nature of the pesticide distribution.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00214846
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