A REBUTTAL TO - THE TOXICITY OF DIQUAT, ENDOTHALL, AND FLURIDONE TO THE EARLY-LIFE STAGES OF FISH

Paul et al. conducted toxicity studies with diquat, endothall and flur idone on fish early life stages (ELS) and generated 24h, 48h, 72h, and 96h LC50 and NOEC values. However, subsequently ''safety margins'' an d ''risk'' for these three herbicides were ascertained by comparing fi sh ELS toxicity data to maximum theoretical herbicide concentrations t hat would result from application as per product label. Paul et al. co ncluded that diquat was more toxic to fish ELS than endothall or fluri done and that the use of diquat provides an inadequate margin of safet y. However, the potential for exposure from chemicals cannot be determ ined from toxicity data and initial concentrations alone. It is essent ial to consider environmental fate. Also, from the available data it i s apparent that Paul et al. were incorrect in some of their assumption s and interpretation of the data and consequently their conclusions re garding diquat are invalid.