Summary. Studies of the influence of formulation, degree of chlorination of the benzene ring and structure of the side chain of some phenoxyalkyl acid herbicides on absorption and translocation were made in a woody plant, Acer macrophyllum Pursh. In an experiment in which the leaves were treated with 2,4‐D or 2,4,5‐T as the acid, triethanolamine salt or 2‐ethylhexyl ester formulations, it was found that absorption increased with decreasing polarity of the molecule. The lower relative mobility of the ester formulations was offset by their greater absorption which resulted in greater accumulation in the roots when compared with the other herbicides. In treatments where dichlorprop or fenoprop formulated as the 2‐ethylhexyl esters were applied, a definite effect of chemical structure was observed on both absorption and translocation. The results of these tests and their implications in the response of big leaf maple are discussed.
Caractères de l'absorption et de la migration de quelques herbicides du groupe des acides phénoxyalkyles dans l'érable a grandes feuilles Acer macrophyllum Pursh.
Rainbow trout (Salmo gairdneri) consumed diets containing 2.3 parts per trillion (10 -x•, pptr), 2.3 parts per billion (10 -9, ppb), and 2.3 ppm TCDD 6 days each week for 105 days, resulting in an average intake of, respectively, 3.2 x 10 -9, 3.6 x 10 -5, or 2.1 x 10 -• •xg/TCDD/g fish, freeze-dry weight per day. Consumption of food containing 2.3 pptr or 2.3 ppb TCDD caused no mortality, no reduction in food consumption or growth, and no fin erosion. Consumption of diets containing 2.3 ppm TCDD caused an average mortality of 50% and 88% in 61 and 71 days, respectively. Feeding activity and growth were also reduced, and fin erosion and liver pathology increased. These data indicate that the "no-effect" level for survival, growth, feeding activity, and fin erosion in rainbow trout receiving TCDD orally is between 2.3 ppm and 2.3 ppb.
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