ALBERT

Notes: The effect of five herbicide safeners on preventing maize (Zea mays L.) injury by acetochlor [N-(2-ethyl-6-methyl-phenyl)-N-(ethoxymethyl)-chloroacetamide], their influence on herbicide uptake and metabolism to a glutathione (GSH) conjugate as well as on GSH content and glutathione S-transferase activity (GST) in untreated and herbicide with/without safener-pre-treated 4-day-old seedlings were determined. The safeners studied were: AD-67 (N-di-chloroacetyl-1-oxa-4-azaspiro-4-5-decane), BAS-145138 [1-dichloroacetyl-hexahydro-3,3,8a-trimethyl-pyrrolo(l,2-a)pyrimidin-6(2H)-one], dichlormid (N, A,-diallyl-2,2-dichlo-roacetamide), DKA-24 (N, N2-diallyl-N2dichloroacetylglycineamide) and MG-191 (2-dichloromethyl-2-methyl-1,3-dioxolane). All safeners significantly increased [14C]acetochlor uptake and metabolism rate, maize GSH content and GST activity. Seedlings receiving BAS-145138 pre-treatment metabolized almost 70% of the absorbed [14C]acetochlor within 10 min.Safener-enhanced GST activity was always found to be higher when [14C]acetochlor was used as the substrate compared with CDNB (1-chloro-2,4-dinitrobenzene). Although DKA-24 had a significantly lower influence on both herbicide metabolism and GST activity, it was nearly as effective a safener as BAS-145138, while the others provided no or poor protection to maize from acetochlor injury when they were not incorporated in the soil. Effets d'antidotes sur la toxicité, la pénétration et le métabolisme de I'acétochlore chez le mats etsur l'activité glutathion S-transférase Cinq antidotes d'herbicides diminuaient la toxicité de 1'acétochlore [N-(2-éthyl-6-méthyl-phényl)-N-(éthoxyméthyl)-chloroacétamide] à I'égard du maïs (Zea mays L.). Lew effet sur l'absorption de l'herbicide et sur son métabolisme en un conjugué avec le glutathion (GSH), de même que leur effet sur la teneur en GSH et 1'activité glutathion 5-transférase (GST) ont étéétudiés sur des maïs âgés de 4 jours. Les antidotes étaient: l'AD-67 (N-dichloroacétyl-1-oxa-4-azaspiro-4,5-décane), le BAS-145138 [1 -dichloroacétyl-hexahydro-3,3,8a-triméthyl-pyrrolo(l,2-a) pyrimidine-6(2H)-one], le di-chlormide (N, N-diallyl-2,2-dichloracétamide), le DKA-24 (N, N2-diallyl-N2-dichloracétylgly-cineamide] et le MG-191 (2-dichlorométhyl-2-méthyl-l,3-dioxolane). Tous les antidotes augmentaient de manière significative 1'absorption et le métabolisme de I'acétochlore 14C, ainsi que la teneur du maïs en GSH et son activité GST. Les jeunes plantes prétraitées avec le BAS-145138 métabolisaient en 10 min près de 70% de I'acétochlore 14C absorbé. L'activité GST stimulée par 1'antidote était toujours plus élevée avec I'acétochlore 14C comme substrat qu'avec le CDNB (1-chloro-2,4-dinitrobenzène).Le DKA-24 avait un effet significativement plus faible que le BAS-145138 sur le métabolisme de l'herbicide et sur l'activité GSH, mais son action antidote était presque aussi importante. Les autres produits n'apportaient au maïs qu'une protection faible ou nulle contre l'acétochlore quand ils n'étaient pas incorporés au sol. Wirkung von Safenern auf die Phytotoxizität, Aufnahme und Metabolismus von Acetochlor und die Glutathion-S-Transferase-Aktivität in Mais Die Wirkung von 5 Safenern (AD-67, BAS-145138, Dichlormid, DKA-24 und MG-191; chemische Bezeichnungen s.o.) auf die Phytotoxizität von Acetochlor für Mais (Zea mays L.) und ihr Einfluß auf die Aufnahme des Herbizids und Metabolismus zu einem Glutathion-(GSH-) Konjugat und auf die Glutathion-S-Transferase-(GST-)Aktivität wurde an 4 Tage alten Keimpflanzen untersucht. Durch die Vorbehandlung mit den Safenern wurden die [14C]-Acetochlor-Aufnahme- und -Metabolierungsrate, der GSH-Gehalt und die GST-Ak-tivität signifikant erhöht. Mit BAS-145138 vorbehandelte Keimpflanzen metabolisierten fast 70% des absorbierten [14C]-Acetochlor innerhalb von 10 min. Die durch die Safener erhöhte GST-Aktivität bei [14C]-Acetochlor als Substrat war im Vergleich zu Chlordinitroben-zen immer höher. Obwohl DKA-24 einen signifikant geringeren Einfluß sowohl auf den Herbizidmetabolismus als auch auf die GST-Aktivität hatte, war es fast so wirkungsvoll wie BAS-145138, während die anderen ohne Einarbeitung in den Boden für den Mais keinen oder geringen Schutz gegen Schäden durch Acetochlor boten.

Notes: Abstract Improvements in the calibration techniques used in a Video Imaging Technique for Assessing Exposure (VITAE) were examined. A series of standard curves measuring change in fluorescence with increased tracer deposition within narrow pre-exposure skin tone groupings on volunteer human subjects were developed. Nine highly linear curves were generated. Data from these curves were used to develop calibration curves which permitted the computerized correction of fluorescence based on the pre-exposure skin fluorescence. VITAE estimates of dermal tracer deposition were highly correlated with application rates (r2=0.98). The fluorescent tracer 4-methyl-7-diethylaminocoumarin was found to be stable for up to 48 h in a greenhouse environment when applied to chrysanthemum foliage or alpha-cellulose patches. The percentage of tracer which could be dislodged from chrysanthemum foliage was constant over 48 h. Improvements in the VITAE calibration techniques increase its value in providing full-body dosimetric estimates of dermal exposure to pesticides in enclosed environments.

Notes: Abstract Exposure of greenhouse chrysanthemum workers to the pesticide pirimicarb was measured by the Video Imaging Technique to Assess Exposure (VITAE) along with air monitoring and biological assessment techniques. Workers at five commercial chrysanthemum operations were video imaged prior to debudding plants which had been treated with a fluorescent tracer and the pesticide, pirimicarb, 36–48 h earlier. After 1–4 h of debudding, workers were again imaged and the rates of tracer deposition determined with the VITAE system. Tracer deposition from contact with treated foliage was found to increase in a linear fashion over 4 h. Greatest deposition occurred on the hands and arms and represented 42% and 20% of total exposure, respectively. No detectable air residue samples of pirimicarb were found while workers were debudding plants. Monitoring of four workers for pirimicarb and its urinary metabolites revealed no detectable residues following 4 h of contact with foliage, which had been treated 48 h earlier.