Though not documented, estrogenic changes might be another sensitive end point. The effects of pesticides on wildlife are also not well-documented. It wasn't until 1985 that the EPA reviewed an insecticide solely on the basis of its effects on wildlife. Since then, the EPA has canceled some pesticides, based partially on their effects on the environment and wildlife. Pesticides, however, have posed a number of problems for agriculture, including the killing of beneficial insects, secondary pest outbreaks and the development of pesticide-resistant pests.
Several studies show a decrease in the effectiveness of pesticides.
A different study concluded that crop losses from pests increased from 31 percent in 1945 to 37 percent in 1990 while during that same period farmers used 33 times more pesticides. As a result, it has become necessary to use larger doses and more frequent applications of pesticides. Combining pesticides, or substituting more expensive, toxic or ecologically hazardous pesticides occurs more frequently. In addition to the problem of pesticide resistance, millions of dollars worth of crops have been lost as a result of improper pesticides application. Although pesticides do offer certain benefits for farmers and other users, new scientific research is uncovering some important health-related issues associated with their use.