<P> Since 1990, research interest has shifted from documenting incidents and quantifying chemical exposure to studies aimed at linking laboratory, mesocosm and field experiments . The proportion of effect - related publications has increased . Animal studies mostly focus on fish, insects, birds, amphibians and arachnids . </P> <P> Since 1993, the United States and the European Union have updated pesticide risk assessments, ending the use of acutely toxic organophosphate and carbamate insecticides . Newer pesticides aim at efficiency in target and minimum side effects in nontarget organisms . The phylogenetic proximity of beneficial and pest species complicates the project . </P> <P> One of the major challenges is to link the results from cellular studies through many levels of increasing complexity to ecosystems . </P> <P> The concept (borrowed from nuclear physics) of a half - life has been utilized for pesticides in plants, and certain authors maintain that pesticide risk and impact assessment models rely on and are sensitive to information describing dissipation from plants . Half - life for pesticides is explained in two NPIC fact sheets . Known degradation pathways are through: photolysis, chemical dissociation, sorption, bioaccumulation and plant or animal metabolism . A USDA fact sheet published in 1994 lists the soil adsorption coefficient and soil half - life for then - commonly used pesticides . </P>

Which of the following is not a long-term effect of pesticides