In his article, “Agriculture exacts a price in the High Sierra,” Cosmo Garvin has indicted California’s Central Valley agriculture for the decline of frogs in the Sierra Nevada (HCN, 5/26/03: Agriculture exacts a price in the High Sierra). Despite the fact that pesticide residues found in mountain frogs are far below lethal levels, the argument seems to be that since declines in frog populations have occurred in mountain regions downwind from agricultural regions, pesticides are responsible.

It is worth noting that these mountain regions are also downwind of large human populations and sources of SO2, NOx, ozone, photochemical smog and other emissions. I would suggest that at this juncture it would make about as much sense to blame the demise of the frogs on backyard barbecue grills.

There are some other problems with the pesticide hypothesis. Synthetic organic pesticides have been used for more than half a century. If pesticides constitute the culprit, why didn’t the frog populations decline long ago, particularly since pesticide applications are now regulated far more stringently?

Also, Lassen Volcanic National Park lies downwind of the Sacramento Valley, while Sixty Lakes Basin (in Kings Canyon National Park) is downwind of the San Joaquin Valley. Cropping patterns are very different in the two areas. The principal crop in the Sacramento Valley is rice, while cotton is the main crop in the San Joaquin Valley. The same pesticides are not generally used on both.

This is a sorry excuse for scientific research.

Donald F. Anthrop
San José, California The author is a professor of environmental studies at San José State University.