No abstract

3H-labelled trifluralin was synthesized by condensation of 3H-4-chloro-3,5-dinitro-alpha,alpha,alpha-triflurotoluene with di-n-propyl-amine. The labelled herbicide was applied to autoclaved and non-autoclaved heavy, light and sandy soils at 30 ppm. The treated samples were incubated for 2 months, then extracted and analyzed for metabolic products and bound (nonextractable) 3H-residues. The amounts of bound residues were higher in autoclaved than in nonautoclaved and in sandy than in either heavy or light soils. The mono- and didealkylated products were detected as well as unknown polar derivatives. 3H-residues bound to preextracted soils were absorbed by bean plants. The roots contained (0.20 - 0.72 ppm) more residues than did the shoots (0.07 - 0.15 ppm) and the uptake was higher in the case of autoclaved especially sandy soils.

14 C-p,p'-DDT-bound residues in soil can be released by treatment with concentrated sulphuric acid at ambient temperatures. Within 6 days, about 70% of the bound residues was released. Bound residues released after 9 months incubation with 14 C-DDT showed the presence of DDT and DDE only while bound residues released after 18 months, contained in addition 13% DDD.Release of bound 14 C-residues also occurs readily following inoculation of the soil-bound residues with fresh soil or with individual microorganisms.Almost complete release of bound residues was observed after incubation for 45 days. The rate of release was rapid during the first two weeks and decreased thereafter. TLC and HPLC analysis showed that the released residues contained DDE (about 80%) and a smaller amount of DDD. The disappearance of DDT from the released residues may be attributed to its microbiological degradation to DDE and DDD, shortly after its release.

The uptake of 32P-labelled Dipterex by the cotton plant (Gossypium barbadense), has been studied following topical application on the leaf, as well as via root. The insecticide did not penetrate into the leaf cells, when applied topically, but is readily taken up by the root, when immersed in a solution of radioactive insecticide. Also the rate of respiration was found to increase significantly in plants treated with sublethal concentrations of Dipterex.The metabolic fate of Dipterex within the plant tissues has been also investigated. Dimethylphosphate, monomethylphosphate and inorganic phosphate have been identified as degradation products of te insecticide.

14C-carbofuran penetrated readily into seeds of Vicia faba and the rate of penetration was found to be dose dependent. The percentage of bound residues was generally low and did not exceed 3% of the applied dose. When the bound residues were fed to rats 46% of the radioactivity was eliminated via CO2 and urine, while tissues contained 25%. Carbofuran phenol and 3-hydroxy carbofuran represented the main metabolites in the urine. These data indicate that bean-bound carbofuran residues are highly bioavailable to rats. Feeding mice with bound carbofuran residues for 90 days led to inhibition of erythrocyte cholinesterase activity after 30 days (35-40%) while the plasma enzyme remained unaffected. Serum transaminases and blood urea nitrogen were significantly elevated, indicating injury to hepatic and renal structures. The results strongly suggest that the bound residues can induce adverse biological effects in mice.