ENVIRONMENTAL EXPOSURES TO AGROCHEMICALS IN THE SIERRA NEVADA MOUNTAIN RANGE

Authors: LENOIR, J - UNIV NEVADA RENO; ASTON, L - PACIFIC TOXICOLOGY LAB; DATTA, SEEMA - UNIV OF NEVADA RENO; McConnell, Laura; FELLERS, G - USGS; Seiber, James

Submitted to: American Chemical Society Symposium Series
Publication Type: Book / Chapter
Publication Acceptance Date: 12/15/1999
Publication Date: 5/1/2000
Citation: Lenoir, J., Aston, L., Datta, S., Fellers, G., McConnell, L.L., Seiber, J.N. 2000. Environmental exposures to agrochemicals in the Sierra Nevada Mountain Range. In: Keith, L.H., Jones-Lepp, T.L., Needham, L.L., editors. Analysis of Environmental Endocrine Disruptors, American Chemical Society Symposium Series. No. 747. p. 53-72.

Interpretive Summary: California presents a unique setting for examining the impact of pesticides on non-target sites. The region's Mediterranean climate supports a diverse year-round agricultural industry. The diversity of crops leads to an intensive pesticide management schedule; more pesticides are applied per acre in California's Central Valley than anywhere else in the United States. Prevailing weather patterns flow east from the Central Valley and up the slopes of the mountains carrying dust, soot, and vapors and redepositing them in the ecosystems of the Sierra Nevada mountains. The deposition of pollutants in the Sierra Nevada is of concern because of the potential impacts the pollutants may have on wildlife and plants. During the last few decades native frog populations throughout California have declined precipitously, and efforts to determine the cause of this decline have been inconclusive. This chapter provides an overview on what is known about atmospheric transport of pesticides from California's Central Valley to the Sequoia National Park on the southwestern slope of the Sierra Nevada Mountain range in Tulare Co., CA. The concentrations of pesticides cited in this chapter are not likely to be causing acute toxicity, but assessing their chronic effect is difficult. Animals in the wild are simultaneously exposed to multiple chemicals through various routes that could contribute additively and act synergistically to contribute to chronic effects. Furthermore, many of the chemicals studied exhibit endocrine disrupting effects. It is understood that endocrine disruptors can act effectively at low concentrations but the threshold concentrations at which their effects are manifested are unknown. The exposure concentrations reported in this chapter should help bridge the gap between field and laboratory tests.

Technical Abstract: California presents a unique setting for examining the impact of pesticides on non-target sites. The region's Mediterranean climate supports a diverse year-round agricultural industry. The diversity of crops leads to an intensive pesticide management schedule; more pesticides are applied per acre in California's Central Valley than anywhere else in the United States. Prevailing weather patterns flow east from the Central Valley and up the slopes of the mountains carrying dust, soot, and vapors and redepositing them in the ecosystems of the Sierra Nevada mountains. The deposition of pollutants in the Sierra Nevada is of concern because of the potential impacts the pollutants may have on wildlife and plants. During the last few decades native frog populations throughout California have declined precipitously and efforts to determine the cause of this decline have been inconclusive. This chapter provides an overview of what is known regarding atmospheric transport of pesticides from California's Central Valley to the Sequoia National Park on the southwestern slope of the Sierra Nevada Mountain range in Tulare county, CA. The concentrations of pesticides presented in this chapter are not likely to be causing acute toxicity, but assessing their chronic effect is difficult. Animals in the wild are simultaneously exposed to multiple chemicals through various routes that could contribute additively and act synergistically to contribute to chronic effects. Furthermore, many of the chemicals studied exhibit endocrine disrupting effects. The exposure concentrations reported in this chapter should help bridge the gap between field and laboratory tests.