Fate of¹⁴C-ethyl prothiofos insecticide in canola seeds and oils

Abstract

Canola plants were treated with (14)C- prohiofos under conditions simulating local agricultural practices. (14)C-residues in seeds were determined at different time intervals. At harvest time about 32 % of (14)C-activity was associated with oil. The methanol soluble (14)C-residues accounted for 12 % of the total seed residues after further seeds extraction, while the cake contained about 49 % of the total residues. About 69 % of the (14)C-activity in the crude oil could be eliminated by simulated commercial processes locally used for oil refining. Chromatographic analysis of crude and refined oil revealed the presence of the parent compound together with three metabolites which were identified as prothiofos oxon, O-ethyl phosphorothioate and O-ethyl S-propyl phosphorothioate, besides one unknown compound. While methanol extract revealed the presence of despropylthio prothiofos and O-ethyl phosphoric acid as free metabolites acid hydrolysis of the conjugated metabolites in the methanol extract yielded 2, 4-dichlorophenole which was detected by color. When rats were fed the extracted cake for 72 hours, the bound residues were found to be bioavailable. The main excretion route was via the expired air (42 %), while the (14)C-residues excreted in urine and feces were 30 % and 11 %, respectively. The radioactivity detected among various organs accounted to 7.5 %.Chromatographic analysis of urine indicated the presence of prothiofos oxon, O-ethyl phosphoric acid and 2, 4-dichlorophenole as main degradation products of prothiofos in free and conjugated form.

Fate of 14C-Ethion Insecticide in the Presence of Deltamethrin and Dimilin Pesticides in Cotton Seeds and Oils, Removal of Ethion Residues in Oils, and Bioavailability of Its Bound Residues to Experimental Animals

“…Compound O,O-diethyl S-hydroxymethyl phosphorodithioate (VI) was detected as a conjugated metabolite, and its concentration was 0.004 ppm ( Table 7). This result agrees with some previous studies, 5,33,34 which noted that in adult rats, prothiofos gave prothiofos oxon, O-ethyl phosphoric acid, and 2,4-dichlorophenole. Fenitrothion insecticide was converted to phosphorothioate and dimethylphosphate.…”

Effect of Refining Processes on Magnitude and Nature of Fenitrothion and Pirimiphos-Methyl Residues in Maize Oil and Bioavailability of their Cake Residues on Rats*

“…Bound 14 C-fenitrothion and 14 C-pirimiphos-methyl in maize seeds proved to be highly bioavailable to rats. The data obtained are in line with many recent studies which indicate a moderate to high bioavailability of soybean bound residues of pirimiphos-methyl (38) , chlorpyrifos (39) , dichlorovos (40) , fenitrothion (41) and canola bound residues of prothiofos (33) .…”

“…Zayed et al, (2,30) showed that the amount of both 14 Ccarbofuran and 14 C-pirimiphos-methyl residues in soybeans oil decreased to 16 % and 25 %, respectively through the refining processes. It is also found that the complete refined sunflower oil obtained from treated sunflower plants lost about 64 % of the total 14 C-zineb residues in crude oil (34) and 69 % of 14 Cprothiofos residues in canola oil (33) .…”

“…It is worthy to mention that, on refining soybeans oil which is contaminated with some organophosphorus insecticides such as malathion, dichlorvos and chlorpyrifos residues, deodorizing process is the most effective step in removing pesticide residues due to combination of decomposition and volatilization (31) . Recently, many authors also reported that, simazie residues in olive oil and prothiofos residues in canola oil are highly eliminated during deodorizing step (32,33) .…”

Nicotine and other potentially harmful compounds in “nicotine‐free” e‐cigarette liquids in Australia

“…There is no Safework Australia exposure standard for 2‐chlorophenol, but it is known to be a respiratory and dermal irritant. Similar chemicals (eg, 2,4‐dichlorophenol) have been identified in canola oil as pesticide residue . Glycerine is a by‐product of biodiesel production, often manufactured from canola oil.…”