“…Numerous aquatic researchers have been concerned about the importance of the water or the food chain, or both, as sources for biological magnification of pesticides in the aquatic environment (Reinert 1967, Chadwick and Brocksen 1969, Grzenda et al 1970, Harrison et al 1970, Macek and Korn 1970, Eberhardt et al 1971, Hamelink et al 1971, Johnson et al 1971, Murphy 1971, Epifanio 1973, and Petrocelli et al 1975. None of these authors, however, presented data relative to situations whgre both types of exposure are involved at threshold levels of chronic toxicity.…”