Environmental risk assessment of pesticide use in high-tech agriculture in a valley of northwest Mexico.

A level 1 Environmental Risk Assessment, based on the USEPA guidelines, was conducted using a risk quotient to evaluate the risk of pesticide use. The Culiacan Valley was chosen as study area because of its importance as agricultural zone in northwest Mexico. Records of pesticide applications allowed the critical contaminants to be identified, and a stratified random sampling was carried out to assess pesticide presence in agricultural soils. For each pesticide detected a toxicity reference value was used, and the risk quotient was determined based on the worst possible scenario for five trophic levels. Critical contaminants such as organochlorines, organophosphates and synthetic pyrethroids represented high risk for aquatic and low risk for terrestrial biota. Overall, the study indicates that a more exhaustive risk assessment should be conducted. This information could be useful in the design of better pesticide regulations aimed at mitigating undesirable environmental consequences.