Dieldrin transport in the insect: an examination of Gerolt's hypothesis

[¹⁴C]-Dieldrin was detected in the hemolymph of adult male Periplaneta americana and P. brunnea 2.5 hr after an acetone solution of radiodieldrin (RD) was applied to the pronotum. Sephadex thin-layer gel filtration (TLG) of cell-free hemolymph (HL) from cockroaches to which RD was applied, and TLG of HL to which RD was added directly, indicated that dieldrin binds to a protein (s) of ca. 18,900 mol wt and two groups of proteins of mol wt ≥ 160,000. The capacity of Periplaneta HL for RD at 22°C was to at least 57 μM, but the highest concentration of RD detected in HL after topical application was 29.9 μM. The hemocytes contained about 37% of the dieldrin in whole cockroach hemolymph. When isolated cockroach legs were perfused with HL containing protein-bound RD, autoradiography of the dissected legs revealed ¹⁴C counts in the tissues. These findings are consistent with the translocation of topical dieldrin by hemolymph, but do not eliminate the possibility of translocation via the tracheal system.     

Herbicide perfluidone (1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl]methanesulfonamide): Its metabolism in rats and chickens

Rats and chickens were each given a single oral dose (10 or 100 mg/kg body wt) of 1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl-¹⁴C(U)]methanesulfonamide ([¹⁴C]perfluidone). Depending on the size of the dose, from 8.4 to 36.2% of the [¹⁴C] was eliminated in the urine and from 36.4 to 85.4% was eliminated in the feces within 48 hr after dosing. Less than 1% of the [¹⁴C] given to laying hens as [¹⁴C]perfluidone was present in the eggs produced during the first 96 hr after dosing. The percentage of the administered [¹⁴C] that remained in these animals (body with G.I. tract and contents removed) varied from 0.34 (96 hr after dosing) to 1.68% (48 hr after dosing). ¹⁴C-labeled compunds in the urine and feces from the rats and chickens were purified by solvent extraction, column chromatography, and gas-liquid chromatography, and then identified by infrared and mass spectrometry. The parent compound was the major ¹⁴C-labeled component in the urine and feces of both animals. 1,1,1-Trifluoro-N-[2-methyl-4-(3-hydroxyphenylsulfonyl)phenyl]methanesulfonamide was present in the feces of both animals. The proposed structures of other metabolites were 1,1,1-trifluoro-N-hydroxy-N-[2-methyl-4-(phenylsulfonyl)phenyl]methanesulfonamide (rat urine) and 1,1,1-trifluoro-N-{2-methyl-4-[(methylsulfonyl)-phenylsulfonyl]phenyl}methanesulfonamide (chicken urine).     

Disposition and metabolism of [14C]chlorpyrifos in the black imported fire ant, Solenopsis richteri Forel

The short-term disposition and metabolism of topically administered [¹⁴C]chlorpyrifos was assessed in the black imported fire ant (Solenopsis richteri Forel) in the presence and absence of the mixed-function oxidase inhibitor piperonyl butoxide. Chlorpyrifos is readily absorbed into an internal organosoluble fraction which was quickly converted into a water-soluble fraction. The radioactivity was slowly excreted over a 24-hr period. Piperonyl butoxide slowed the conversion of the internal organosoluble radioactivity to the water-soluble fraction. Thin-layer chromatography indicated that piperonyl butoxide slowed the conversion of chlorpyrifos to material remaining at the origin, presumably water-soluble metabolites. The results of acid hydrolysis studies indicated that the water-soluble radioactivity was comprised mainly of conjugates. Although very little chlorpyrifos oxon was recovered in the metabolism experiments, in vitro studies on fire and head homogenates showed the compound to be an extremely potent anticholinesterase, with an I₅₀ of 4.6 × 10^?10M, while a major metabolite, 3,5,6-trichloropyridinol, was an ineffective acetylcholinesterase inhibitor.     

Intestinal uptake,metabolism, and transport of naphthol: In vitro capacity,requirements, and inhibition

The metabolism and transport of [¹⁴C]-naphthol were investigated in sacs of rat small intestine to better understand metabolism of the pesticide carbaryl (which contains naphthol) in the intestine. The capacity to synthesize polar ¹⁴C-labeled metabolites was approximately saturated at 50 μM naphthol. The metabolic capacity of the cranial small intestine was about two times the capacity of the caudal. Anaerobic incubation severely suppressed naphthol metabolism. Sodiumfree medium suppressed metabolism only slightly but altered transport of water and of the polar ¹⁴C-labeled metabolites to serosal and mucosal fluids; the effect on metabolite transport cannot be explained by the effects of sodium on water movements, however. Calcium-free medium did not affect metabolism or metabolite transport; 2,4-dinitrophenol, and possibly phlorizin, but not ouabain, suppressed naphthol metabolism in specific regions of the intestine. Each of the three inhibitors altered metabolite transport. It is concluded that the capacity to conjugate naphthol in the small intestine is greater in the cranial than caudal regions; the quantity of naphthol taken up from the medium is proportional to the rate of formation of the polar metabolite, naphthyl glucuronide; addition of 2,4-dinitrophenol, phlorizin, or ouabain, or deletion of sodium, perturbed the transport of the polar metabolite, but the perturbance could not be explained by the effect on rate or direction of fluid transfer and indicated an effect on cellular permeability or on transport mechanisms; the effect of the three inhibitors and possibly of elevated naphthol concentrations (to 520 μM) in the medium on metabolite transport may be by a sodium interaction; the latter suggests that naphthol may be toxic to the intestine at concentrations approaching 100 to 1000 μM.     

Mercapturic acid formation in the metabolism of propachlor,CDAA, and fluorodifen in the rat

When [¹⁴C]F₃-fluorodifen (2,4′-dinitro-4-trifluoromethyl diphenylether), carbonyl-[¹⁴C]CDAA (N,N-diallyl-2-chloroacetamide), and carbonyl-¹⁴C-propachlor (2-chloro-N-isopropylacetanilide) were fed to rats, 57 to 86% of the ¹⁴C was excreted via the urine within 48 hr. Although very little radioactivity was excreted in the feces of CDAA-treated rats, 15–22% of the ¹⁴C was excreted in the feces of propachlor- of fluorodifentreated rats and an average of 8% of the ¹⁴C remained in these rats 48 hr after treatment. Oxidation of the ¹⁴C label to [¹⁴C]O₂ was not a major process in the metabolism of these herbicides. The only major radioactive metabolite present in the 24-h urine of fluorodifen-treated rats, 2-nitro-4-trifluoromethylphenyl mercapturic acid, accounted for 41% of the administered dose of ¹⁴C. In the metabolism of CDAA, the corresponding mercapturic acid accounted for 76% of the dose; it was the only major metabolite present in the 24-h urine. In contrast, three major metabolites were detected in the 24-h urine of propachlortreated rats, and the mercapturic acid accounted for only 20% of the dose. The mercapturic acid of each herbicide was identified by mass spectrometry.     

The metabolism of 1-naphthyl methylcarbamate by Periplaneta americana

The in vivo release of ¹⁴CO2 arising from decarbamoylation of l-naphthyl methyl [¹⁴C]carbamate (carbaryl) injected into male and female Periplaneta americana was measured over the range from 0.2 to 50 nmol carbaryl/g body weight. The amount of ¹⁴CO2 released was proportional to the dose of [¹⁴C]-carbaryl injected and was not significantly different between male and female cockroaches. Carbaryl was found to be more toxic to male (KD100, 12 nmol carbaryl/g) than female (KD100′ 57 nmol carbaryl/g) cockroaches, at any dose which caused knockdown, females showed a greater ability to recover from the toxic syndrome than did males. The [¹⁴C]-carbaryl metabolism (decarbamoylation) was temperature dependent and could be partially inhibited by sesamex, tri-orthocresyl phosphate and anoxia. Secondary effects of carbaryl poisoning were severe dehydration of the animals and in some cases abdominal swelling due to air being gulped into the crop. The amount of dehydration was essentially unaltered by the chemical inhibitors, but was partially reduced by anoxia and cooling. In the most severe cases of dehydration animals lost 18 % of their body water content.     

Tracing a 14C-labeled carbamate molluscicide through the digestive system of deroceras reticulatum (müller)

The passage of a ¹⁴C-labeled carbamate, 2-(2-chloro-1-methoxy-' ethoxy)phenyl N-methylcarbamate, or its labeled metabolites through the alimentary system of the grey garden slug Deroceras reticulatum was examined by autoradiographic studies and scintillation counting. It was demonstrated that, in a first step, the molluscicide penetrated the cells of the oesophagus and the crop. It was quickly transported by the hemolymph to the periphery of the body and re-entered the cells of the digestive tract and the mid-gut gland in a second step from the hemolymph side. The crypt cells of the mid-gut gland are discussed as cells involved in detoxification, and connective tissue cells as the major storage sites of the labeled material. Excretion in feces and secretion in mucus are thought to be the routes of ¹⁴C elimination.     

DDT-lipoprotein complex in the American cockroach hemolymph: A possible way of insecticide transport

The binding in vitro of ¹⁴C-DDT to proteins from the hemolymph of the American cockroach was shown by means of electrophoresis and isoelectric focusing on polyacrylamide gels. The study of ¹⁴C-DDT penetration into the insect implies the hemolymph as one of the possible manners by which this insecticide could penetrate the central nervous system, and other target organs. The possibility of DDT being transported by the hemolymph bound to lipoproteins is discussed.     

The in vivo sensitivity of ATPases to DDT,DDE, and physical immobilization in American cockroaches

American cockroaches injected with sublethal doses of DDT (0.75 μg/roach) at 5-day intervals showed a 40% reduction in oligomycin-sensitive Mg²⁺ATPase from muscle homogenates, and a 23% reduction of Na⁺-K⁺ATPase from nerve cords. Thus, the maximum effect measured occurred with the same enzyme and tissue as determined from in vitro studies. The metabolite, DDE, used at 15 μg per roach, gave no significant change in activity of the ATPase system following injection. In contrast, high single doses of DDT (7.5 μg/roach) and 100 μg DDE and dicofol per roach caused over 30% increase in oligomycin-sensitive Mg²⁺ATPase of muscle and a 10–15% increase in Na⁺-K⁺ATPase of nerve cords measured 24 and 48 hr later. While a similar response was observed for Mg²⁺ATPase activities in cockroaches that were immobilized, the increase in enzyme activities were much greater than that caused by the pesticides.     

A study of ethylene and CO2 evolution from ethephon in tobacco

Buffers and leaf discs of mature tobacco (Nicotiana tabacum L.) were utilized to study [¹⁴C]-ethylene and ¹⁴CO₂ evolution from radiolabeled ethephon, (2-chloroethyl)phosphonic acid. Metabolic fate of [¹⁴C]ethephon in leaf discs was investigated by use of thin-layer chromatography, high-voltage paper electrophoresis, autoradiography, and liquid scintillation spectroscopy. The evolution of labeled ethylene generally increased with increasing buffer pH, buffer volume, and dosage of [¹⁴C]ethephon. [¹⁴C]Ethylene was evolved, increasingly with time, from [¹⁴C]ethephon either added to the buffer or applied to leaf discs. The rate of [¹⁴C]ethylene evolution was maximum during the first day and leveled off on the fourth day. More than 50% of the total [¹⁴C]ethylene evolution over a 96-hr period was recovered during the first 24 hr after [¹⁴C]ethephon application. No ¹⁴CO₂ was evolved when [¹⁴C]ethephon was degraded in the presence of buffer or leaf discs. Only ethephon itself, and no detectable metabolite thereof, was discovered in the methanolic extract of the leaf disc tissue. An insignificant amount of ¹⁴C activity (approximately 2% of the extracted ¹⁴C) was detected in the residue. By means of gas chromatography, it was confirmed that in buffers and tobacco leaf tissue ethephon breaks down to release ethylene but not CO₂.     

Chlorpyrifos degradation in soil at termiticidal application rates

Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] is an organophosphorus insecticide applied to soil to control pests both in agricultural and in urban developments. Typical agricultural soil applications (0.56 to 5.6 kg ha^?1) result in initial soil surface residues of 0.3 to 32 μg g^?1. In contrast, termiticidal soil barrier treatments, a common urban use pattern, often result in initial soil residues of 1000 μg g^?1 or greater. The purpose of the present investigation was to understand better the degradation of chlorpyrifos in soil at termiticidal application rates and factors affecting its behaviour. Therefore, studies with [¹⁴C]chlorpyrifos were conducted under a variety of conditions in the laboratory. Initially, the degradation of chlorpyrifos at 1000 μg g^?1 initial concentration was examined in five different soils from termite-infested regions (Arizona, Florida, Hawaii, Texas) under standard conditions (25°C, field moisture capacity, darkness). Degradation half-lives in these soils ranged from 175 to 1576 days. The major metabolite formed in chlorpyrifos-treated soils was 3,5,6-trichloro-2-pyrid-inol, which represented up to 61% of applied radiocarbon after 13 months of incubation. Minor quantities of [¹⁴C]carbon dioxide (< 5%) and soil-bound residues (? 12%) were also present at that time. Subsequently, a factorial experiment examining chlorpyrifos degradation as affected by initial concentration (10, 100, 1000 μg g^?1), soil moisture (field moisture capacity, 1.5 MPa, air dry), and temperature 15, 25, 35°C) was conducted in the two soils which had displayed the most (Texas) and least (Florida) rapid rates of degradation. Chlorpyrifos degradation was significantly retarded at the 1000 μg g^?1 rate as compared to the 10 μg g^?1 rate. Temperature also had a dramatic effect on degradation rate, which approximately doubled with each 10°C increase in temperature. Results suggest that the extended (3–24 + years) termiticidal efficacy of chlorpyrifos observed in the field may be due both to the high initial concentrations employed (termite LC ₅₀ = 0.2– 2 μg g^?1) and the extended persistence which results from employment of these rates. The study also highlights the importance of investigating the behaviour of a pesticide under the diversity of agricultural and urban use scenarios in which it is employed.     

Investigations on the Behaviour of Fenpropimorph and its Metabolite Fenpropimorphic Acid in Soils

The fate of fenpropimorph and its metabolite fenpropimorphic acid was investigated in a silty sand soil and in a clayey silt soil. In laboratory and field experiments fenpropimorph disappeared without a lag phase. A few days after application fenpropimorphic acid was detected. Additional laboratory experiments with [¹⁴C]fenpropimorph emphasized the significance of mineralization and the formation of non-extractable residues. The determination of soil/water distribution coefficients of parent compound and metabolite yielded a higher leaching potential for fenpropimorphic acid due to its higher polarity. This was confirmed by performing a laboratory column test under worst-case conditions. Under field conditions, however, fenpropimorphic acid was detected only in the superficial soil layers (0–5 cm) of both investigation sites at very low concentrations.     

Metribuzin metabolism in tomato: Isolation and identification of N-glucoside conjugates

Metribuzin [4-amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one] metabolism was studied in tomato (Lycopersicon esculentum Mill. “Sheyenne”). Pulse-treatment studies with seedlings and excised leaves showed that [5-¹⁴C]metribuzin was rapidly absorbed, translocated (acropetal), and metabolized to more polar products. Foliar tissues of 19-day-old seedlings metabolized 96% of the root-absorbed [¹⁴C]metribuzin in 120 hr. Excised mature leaves metabolized 85–90% of the petiole-absorbed [¹⁴C]metrubuzin in 48 hr. Polar metabolites were isolated by solvent partitioning, and purified by adsorption, thin-layer, and high-performance liquid chromatography. A minor intermediate metabolite (I) was identified as the polar β-d-(N-glucoside) conjugate of metribuzin. The biosynthesis of (I) was demonstrated with a partially purified UDP-glucose: metribuzin N-glucosyltransferase from tomato leaves. A possible correlation between foliar UDP-glucose: metribuzin N-glucosyltransferase activity levels and differences in the tolerance of selected tomato seedling cultivars to metribuzin was suggested. The major polar metabolite (II) was identified as the malonyl β-d-(N-glucoside) conjugate of metribuzin.     

Degradation of fluridone in submersed soils under controlled laboratory conditions

The experimental, aquatic herbicide fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) was degraded in two submersed soils and in the water above those soils to one acidic metabolite (identified as 1,4-dihydro-1-methyl-4-oxo-5-[3-(trifluoromethyl)phenyl]-3-pyridinecarboxylic acid by mass spectrometry). A sandy and a silt loam soil were treated with [¹⁴C]fluridone, immersed in water, and analyzed after 1, 3, 5, 7, 9, and 12 months. Seven to fifteen percent of the ¹⁴C applied to the soils was recovered in the water on each of the various collection dates. The acidic metabolite accounted for 86 to 93% of the radioactivity in the water fraction 7 months after treatment. The metabolite was absorbed strongly by both soils and comprised about 60% of the total ¹⁴C in each soil after 12 months. The remainder of the ¹⁴C in the soils after 12 months was either the parent compound (～30%) or an undefined insoluble residue (～10%).     

Comparative uptake and metabolism of methazole in prickly sida and cotton

The comparative uptake and metabolism of ¹⁴C-labeled 2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione (methazole), a herbicide, in prickly sida (Sida spinosa L.) and cotton (Gossypium hirsutum L.) were investigated as physiological bases for herbicidal selectivity, using thin layer chromatography, autoradiography, and liquid scintillation counting. Prickly sida and cotton readily absorbed and translocated ¹⁴C from nutrient solution containing [¹⁴C]methazole. Only acropetal translocation of ¹⁴C was observed. Methazole was rapidly metabolized to 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) and other metabolites by both species. Although metabolism appeared to be qualitatively the same, quantitative differences between species were evident. Methazole was converted to DCPMU (also phytotoxic) more readily by prickly sida than cotton; however, DCPMU was more readily detoxified to 1-(3,4-dichlorophenyl) urea (DCPU) by cotton than prickly sida. More ¹⁴C per unit weight was present in the prickly sida shoots than in cotton shoots. Also, a larger portion of the methanol-extractable ¹⁴C was herbicidal in the shoots of prickly sida than of cotton. Thus, the differential tolerances of prickly sida and cotton to methazole may be explained, in part, by differential uptake and metabolism of methazole and DCPMU.     

The metabolism of the nonionic surfactant 14C-labeled α[p-1,1,3,3-tetramethylbutyl)phenyl]-ω-hydroxyhexa(oxyethylene) in the goat

A goat given a single dose of ¹⁴C-labeled α-[p-(1,1,3,3-tetramethylbutyl)phenyl]-ω-hydroxyhexa(oxyethylene) ([¹⁴C]TOP-6EOH) eliminated 18% of the ¹⁴C in the urine and 77% in the feces within 96 hr after dosing. Another goat (surgically modified for total bile collection) given a single dose of [¹⁴C]TOP-6EOH eliminated 81% of the ¹⁴C in the bile, 17% in the urine, and only 6% in the feces. When ¹⁴C-bile from the animal in the second study was perfused into the small intestine of a third goat, 72% of the ¹⁴C was eliminated in the feces, 20% in the bile, and 6% in the urine within 96 hr. Eighteen different types of metabolites accounting for most of the ¹⁴C in the bile and urine were isolated, derivatized, and then characterized by mass spectral analysis. The [¹⁴C]TOP-6EOH was metabolized by: (i) oxidation of the alkyl group to give alcohols and acids, (ii) oxidation of the terminal ethylene oxide moiety to an acid, (iii) cleavage of the polyoxyethylene side chain, (iv) combinations of i–iii, and (v) conjugation of the products of i–iv.     

Metabolic fate of bioxone in cotton

The metabolic fate of the ¹⁴C-labeled herbicide, 2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione (bioxone), in cotton (Gossypium hirsutum L. “Acala 4-42-77”) was studied using thin-layer chromatography, autoradiography, and counting. Bioxone-¹⁴C was readily metabolized by cotton tissue to 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) and 1-(3,4-dichlorophenyl)urea (DCPU). Leaf discs metabolized bioxone-¹⁴C rapidly; 12 hr posttreatment, 65% of the ¹⁴C in methanol extracts was in forms other than intact herbicide. Excised leaves treated through the petiole with either heterocyclic ring-labeled or phenyl ring-labeled herbicide contained little bioxone-¹⁴C after 1 day; DCPMU was formed early then decreased with time. DCPU accounted for 55–70% of the ¹⁴C in excised leaves 3 days posttreatment. In intact plants treated via the roots, the herbicide was rapidly metabolized in the roots to DCPMU and DCPU; little or no intact herbicide was translocated to the leaves. Little radioactivity accumulated in the roots with time; the radioactivity in the leaves accounted for 80–90% of the methanol-soluble ¹⁴C 47 days posttreatment. Most of the ¹⁴C in the leaves was recovered as DCPU (50–60%) and unidentified polar metabolite(s) which remained at the origin of the thin-layer plates (30–40%). The percentage of radioactivity which remained in cotton residue after methanol extraction increased with time. Digestion of the plant residues with the proteolytic enzyme pronase indicated that some of the nonextractable ¹⁴C may be DCPMU and DCPU complexed with proteins. Similar metabolic patterns were noted after treatment with either heterocyclic ring-labeled or phenyl ring-labeled bioxone-¹⁴C. Generally, bioxone was metabolized to DCPMU which in turn was demethylated to DCPU. The herbicide and DCPMU were 20 times as toxic as DCPU to oat (Avena sativa L.), a susceptible species.     

Studies into the differential activity of the hydroxybenzonitrile herbicides: II. Uptake,movement and metabolism in two contrasting species

Uptake, movement, and metabolism of unformulated ioxynil and bromoxynil salts were investigated in Matricaria inodora and Viola arvensis. The morphology of these two species did not give rise to different spray retention and contact angles. After 7 days, uptake of [¹⁴C]ioxynil-Na reached 8.26% of applied ¹⁴C activity in M. inodora and 16.77% of that in V. arvensis compared with 1.54 and 3.83%, respectively, for [¹⁴C]bromoxynil-K. Over 98% of the ¹⁴C activity detected in the plant after 7 days remained in the treated leaves of V. arvensis following [¹⁴C]ioxynil-Na treatment. However, 8.7% of the ¹⁴C activity detected in [¹⁴C]ioxynil-Na-treated M. inodora was recovered from the apex and developing leaves reflecting a greater translocation. [¹⁴C]Bromoxynil-K was more mobile in both species and after 7 days 87.5 and 91.39% were detected in the treated leaves of M. inodora and V. arvensis, respectively. In both species the majority of translocated ¹⁴C activity was recovered from the apex and developing leaves. Up to 20% of the applied [¹⁴C]ioxynil-Na and [¹⁴C]bromoxynil-K was not detected within the treated plant. Extraction of treated plants revealed no detectable metabolic breakdown of ioxynil-Na to halogenated derivatives in either species. However, metabolic breakdown of bromoxynil-K was apparent in V. arvensis. No significant root exudation was detected when [¹⁴C]ioxynil-Na and [¹⁴C]bromoxynil-K were applied to hydroponically grown S. media and V. arvensis. Losses of ¹⁴C activity were due to herbicide volatility or degradation to volatile products on the leaf surface.     

Metabolism of the insecticide SD 8280, 2-chloro-1-(2,4-dichlorophenyl)vinyl dimethyl phosphate,following its application to rice

The metabolism of the insecticide SD 8280 [2-chloro-1-(2,4-dichlorophenyl)vinyl dimethyl phosphate] in rice plants has been examined. When rice seedlings were treated with [¹⁴C]-SD 8280 the major metabolite was 1-(2,4-dichlorophenyl)ethanol which was present mainly conjugated with plant carbohydrates. This compound was also the major metabolite present in grain and straw from rice treated with [¹⁴C]-SD 8280 and grown to maturity under paddy conditions both in the glasshouse and in an outdoor enclosure. Other metabolites detected in the mature plants included 2-chloro-1-(2,4-dichlorophenyl)vinyl methyl hydrogen phosphate and 2,4-dichloro-benzoic acid, both of which occurred in free and conjugated forms. Paddy water was sampled at intervals after the application of [¹⁴C]-SD 8280 and the total residue in the water fell from initial levels of 0.28–1.1 μg/ml (expressed as SD 8280 equivalent) immediately after treatment to <0.01 μg/ml after 2–3 weeks. The total residues in the soil from these experiments were low and did not exceed 0.20 mg/kg (SD 8280 equivalents) through the 0–15 cm profile.     

Animal metabolism of propham (isopropyl carbanilate): The fate of residues in alfalfa when consumed by the rat and sheep

Alfalfa was root-treated with [¹⁴C]propham (isopropyl carbanilate[¹⁴C-phenyl(U)]) for 7 days and then harvested and freeze-dried. Rats and sheep were orally given either ¹⁴C-labeled alfalfa roots ([¹⁴C]root) or ¹⁴C-labeled alfalfa shoots ([¹⁴C]shoot). When the [¹⁴C]root was given, 6.5–11.0% of the ¹⁴C was excreted in the urine and 84.6–89.4% was excreted in the feces within 96 h after treatment. Less than 3% of the ¹⁴C remained in the carcass (total body—gastrointestinal tract and contents) 96 h after treatment. When [¹⁴C]shoot was given, 53.2–55.2% of the ¹⁴C was excreted in the urine, 32.1–43.4% was excreted in the feces, and the carcass contained 0.2–1.1% of the ¹⁴C 96 h after treatment. When the insoluble fraction (not extracted by a mixture of CHCl₃, CH₃OH, and H₂O) of both alfalfa roots and shoots was fed to rats, more than 86% of the ¹⁴C was excreted in the feces and less than 3% remained in the carcass 96 h after treatment. The major radiolabeled metabolites in the urine of the sheep fed ¹⁴C shoot were purified by chromatography and identified as the sulfate ester and the glucuronic acid conjugates of isopropyl 4-hydroxycarbanilate. Metabolites in the urine of the sheep treated with [¹⁴C]root were tentatively identified as conjugated forms of isopropyl 4-hydroxycarbanilate, isopropyl 2-hydroxycarbanilate, and 4-hydroxyaniline. The combined urine of rats dosed with [¹⁴C]shoot and [¹⁴C]root contained metabolites tentatively identified as conjugated forms of isopropyl 4-hydroxycarbanilate, isopropyl 2-hydroxycarbanilate, and 4-hydroxyaniline.