BIOAVAILABILITY IN RATS OF BOUND PESTICIDE-RESIDUES FROM TOLERANT OR SUSCEPTIBLE VARIETIES OF SOYBEAN AND CANOLA TREATED WITH METRIBUZIN ORATRAZINE

Susceptible or tolerant varieties of soybean treated with metribuzin, or canola treated with atrazine were grown in a controlled environment . Shoots and fruits were harvested at maturity and extracted exhaustiv ely with methanol. The extracted materials containing bound C-14 resid ues were subsequently fed to rats for two days. The elimination of C-1 4 in urine and feces was monitored for 4 days and the distribution or radioactivity in liver, kidney and heart was studied. Higher C-14 resi dues in urine were present in animals fed fruits compared to shoots of soybean or canola of both susceptible and tolerant varieties. The bou nd atrazine residues from the pods of Atr Tower (tolerant variety of c anola) were more bioavailable than Tower (susceptible variety of canol a). Bioavailability of bound atrazine from the shoots of canola in bot h varieties was very low. In soybean fed animals, bound metribuzin der ived C-14 from the susceptible variety (Maple Amber) was more bioavail able than from the resistant variety (Maple Arrow). However, feeding t he animals with susceptible or tolerant varieties of soybean or canola containing bound residues of C-14 metribuzin or C-14 atrazine for two days did not result in the accumulation of radioactivity in the body organs studied. Thus our data show that the bioavailability of these b ound pesticides was dependent on the type of plant parts ingested and the variety of plant species. (C) 1997 Elsevier Science Ltd.