Chlorpyrifos aquatic organisms

Menconi, M. and A. Paul. 1994. Hazard Assessment of the Insecticide Chlorpyrifos to Aquatic Organisms in the Sacramento-San Joaquin River System. Calif. Dept. Fish Game, Environ. Serv. Div., Admin. Rep. 94-1. 74 pp. 

Moore, M.T., D.B. Huggett, W.B. Gillespie Jr., J.H. Rodgers Jr., and C.M. Cooper. 1998. Comparative toxicity of chlordane, chlorpyrifos, and aldicarb to four aquatic testing organisms. Arch. Environ. Contam. Toxicol. 34 152-157. 

Develop suitable replacements for chlorpyrifos in mosquito control programs. These replacement compounds should exhibit a relatively long half-life in aquatic environments while avoiding the broad-spectrum toxicity typical of chlorpyrifos to large numbers of nontarget organisms. 

Chlorpyrifos-methyl. Two applications six days apart of 0.007 kg chlorpyrifos-raethyl/ha to a forest block had no noticeable effect on breeding songbird populations and induced only limited drift increases of aquatic invertebrates without significantly altering benthos populations or native fish diets (32). Applications of 0.72-0.86 kg chlorpyrifos-methyl/ha to streams caused severe disturbances of aquatic invertebrates and substantial depressions of benthos populations for several months (33). Diets of native fish were significantly altered due to effects on fish food organisms. Some mortality of crayfish and minnows was observed, but no brook trout mortality occurred. Chlorpyrifos-methyl has not been developed for forestry use in Canada. 

The cotton landscape example presented above reveals that landscape-level risk assessment can be conducted by investigating the influence of the surrounding landscape on the emission of insecticides to the water bodies of concern in order to characterize more realistically actual exposure concentrations. This relatively simple approach addresses variability within the landscape, but pays less attention to the interactions between water bodies. A more complex approach is to assess the fate and effects of a chemical (or combination of stressors) for the entire watershed and to consider this watershed as a true continuum. The latter approach may include all water bodies within a watershed and addresses their interdependence, for example, by studying the flow of water, chemicals, matter, and organisms between these systems. An example of such a watershed approach is the study of Pandovani et al. (2004). They used a landscape-level approach to assess aquatic exposure via spray drift of chlorpyrifos-methyl in the watershed of the Simeto River in Sicily (Italy). 

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