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Biomedical subjects

C R Harris

Publications and source records attributed to C R Harris.

At least 55 records · Page 3Linked to original sources
PubMed1982

Persistence of isofenphos and isazophos in a mineral and an organic soil.

Isofenphos (Amaze (R), Oftanol (R), BAY 92114, 1-methylethyl 2- [[ethoxy [(1-methylethyl)amino] phosphinothioyl] oxy] benzoate) (20% granular) and isazophos (Miral (R), CGA 12223, 0,0-diethyl 0- [1-isopropyl-5-chloro-1,2,4-triazolyl(3)] phosphorothioate) (50% emulsifiable concentrate) were applied at 3.4 Kg AI/ha and incorporated into sand and muck soil contained in small field plots. Soil samples were taken at intervals, extending over 2 yr in the case of isofenphos. Radishes and carrots served as indicator crops for absorption of insecticides. Soil and crop samples were extracted and analyzed for the insecticides by glc. Isazophos residues in soil declined rapidly with ca. 50% of the initial applications remaining after 2 and 5 wk in the sand and muck respectively, and less than 1 and 3% after 1 yr. Isofenphos residues declined slowly with ca. 50% of the initial application remaining at 12 wk in both soil types. Residues of isofenphos after 1 yr were 15 and 45% of the initial application to sand and muck, respectively, and after 2 yr they had declined to 4 and 14%, respectively. Residues of both materials in radishes and carrots generally did not exceed 0.04 ppm except for carrots grown the first yr in isofenphos treated sand, where 0.25 ppm was found.

Organothiophosphorus Compounds↗
PubMed1981

Adsorption, desorption, soil mobility and aqueous persistence of fensulfothion and its sulfide and sulfone metabolites.

Soil/water interactions with the insecticide fensulfothion and its sulfide and sulfone metabolites and described. Adsorption to, and desorption from four soils were studied. There was a general inverse relationship between water solubilities of the three chemicals and their adsorption K values. Order of adsorption was f. sulfide greater than f. sulfone greater than fensulfothion. Adsorption K values correlated significantly with soil organic content. Desorption of fensulfothion and the sulfone were similar whereas the less soluble sulfide desorbed to a lesser extent. To facilitate comparison of desorption tendencies of the three compounds of desorption index was developed. Mobilities through the soils were directly related to the water solubilities of the three chemicals. Mobilities in decreasing order were - fensulfothion greater than f. sulfone greater than f. sulfide. Persistence of fensulfothion was similar in both sterile and non-sterile natural water - about 50% remaining at the end of the 16 wk experiment. Under reducing conditions fensulfothion disappeared from water in 8-12 wk with almost complete conversion to the sulfide.

Adsorption↗
PubMed1981

A laboratory study of the persistence of carbofuran and its 3-hydroxy- and 3 keto-metabolites in sterile and natural mineral and organic soils.

In a laboratory study, the persistence of carbofuran and its 3-hydroxy- and 3-keto-metabolites was examined separately over 16 wk in sterile and natural organic (muck) and mineral (loam) soils. Carbofuran was relatively persistent in sterile soils; at 8 wk 77% remained in the sterile muck and about 50% remained in the sterile loam. In the natural muck 25% of initial carbofuran remained at wk whereas in the natural loam carbofuran had completely disappeared by that time. The 3-ketocarbofuran was very short-lived even in the sterile muck where only 50% remained at 1 wk. The 3-hydroxycarbofuran degraded appreciably on zero day in the natural soils (with conversion to 3-keto-carbofuran) and about 90% had disappeared in 1 wk. A more detailed study of the persistence of 3-hydroxycarbofuran in the natural soils showed complete disappearance in 2 days in loam and in 3 days in muck. The 3-ketocarbofuran produced from the 3-hydroxy-carbofuran reached a maximum concentration in 1 day and then disappeared within 4 days in loam and about 1 wk in muck.

Actinomycetales↗
PubMed1981

Persistence of four pyrethroid insecticides in a mineral and an organic soil.

Permethrin, cypermethrin, fenpropanate and fenvalerate (emulsifiable concentrates) were applied at 280 g AI/ha and incorporated into mineral and organic soil contained in small field plots. Radishes and carrots were grown to serve as indicators of insecticide uptake. Similar plots were treated with the same insecticides at 140 g AI/ha and the soil surface was left undisturbed following application. Soil cores were removed at appropriate intervals and the crops were harvested when mature. The insecticide concentration in all samples was determined by gas-liquid chromatography. The amount of insecticide in the soil declined rapidly to less than 50% of the initial value in 1 month or less for most material-soil-treatment combinations and within 2 months for all cases. Concentrations remained in excess of 0.01 ppm in the organic soil for at least six months for all material-treatment combinations but fell below this level over 2-5 months in the mineral soils. Organic soil incorporated fenvalerate was the most persistent combination overall with 25, 17 and 7% remaining at 6, 18 and 28 months respectively. The trans-isomers of permethrin and cypermethrin disappeared more quickly than the cis-isomers but the insecticidally active IR isomers were not preferentially degraded relative to the inactive 1S. No residues (less than 0.01 ppm) were found in the radish or carrot crops. First order disappearance rates were not constant for any of the combinations. A comparison of partial rate constants showed: 1) 0-1 mo rates were generally greater in mineral than organic soil, 2) 1-6 mo rates in organic soil were lower than 0-1 mo rates, 3) 1-6 mo rates for surface applications to organic soil were generally less than for incorporated applications. In laboratory experiments, 0-1 mo rates for fenvalerate disappearance in a mineral soil were 2-3x greater for 0.5 ppm than for 10 ppm while 1-6 mo rates were independent of insecticide concentration but were 1.5x greater for 0.5% moisture than for 5%.

Biodegradation, Environmental↗
PubMed1980

Persistence of chlorpyrifos in a mineral and an organic soil.

Chlorpyrifos (Lorsban emulsifiable concentrate) was applied at 3.4 kg AI/ha and incorporated into sand and muck soil contained in small field plots. Soil samples were taken at intervals over 2 yr. Radishes and carrots, seeded yearly, served as indicator crops for absorption of insecticide residues. Samples were extracted and analyzed, by gas-liquid chromatography, for chlorpyrifos, oxychlorpyrifos, and 3,5,6-trichloro-2-pyridinol. Chlorpyrifos residues declined rapidly, with 50% of the initial application remaining after 2 and 8 wk in sand and muck, respectively, and 4 and 9% after 1 yr. Pyridinol residues increased to 13 and 39% of the initial chlorpyrifos application in sand and muck after 1 and 8 wk, respectively, and declined thereafter. Oxychlorpyrifos was detected in the 2 soils at very low levels only in immediate posttreatment samples. In the first year of the study low levels (less than 0.1 ppm) of chlorpyrifos and the pyridinol were detected in radishes and carrots.

Chlorpyrifos↗
PubMed1979

Determination of residues of methomyl and oxamyl and their oximes in crops by gas-liquid chromatography of oxime trimethylsilyl ethers.

The gas-liquid chromatographic behavior of methomyl (methyl N-[(methyl-carbamoyl)oxy]thioacetimidate), oxamyl (methyl N',N'-dimethyl-N-[(methylcarbamoyl)oxyl]-1-thiooxamimidate), their respective oxime hydrolysis products and the trimethylsilyl (TMS) ethers of the oximes on 5% OV-1 was studied under isothermal conditions using a flame-photometric detector in the sulfur-selective mode. In contrast to the behavior of the parent carbamates and underivatized oximes, the oxime-TMS ethers readily produced symmetrical peaks of consistent size. Quantities of derivative equivalent to at least 0.25 ng of oxime were easily measurable. Derivative formation was reproducible for standards over the range 10.0 to 0.25 microgram/ml in benzene and at 10.0 and 0.50 microgram/ml in the presence of extractives from tomato, carrot and celery at concentrations equivalent to 10 g/ml of crop. Derivative yields from crop extract fotifications were 89% or better in most cases. Both the carbamates and oximes were simply and consistently recovered in high yield from crops fortified at 1.00 and 0.05 ppm using the procedures described. The inclusion of a second analytical step provided separate analysis for oximes and carbamates. The application of these observations to the analyses of residues in crops is discussed.

Carbamates↗
PubMed1979

Carbofuran residues in organic soils in Southwestern Ontario, 1977.

Organic soils from 22 farms with a history of carbofuran use for soil insect control were sampled in November, 1977. Analysis for carbofuran was by electron capture gas chromatography of the heptaflurobutyric derivative. Nineteen of the 22 soils contained detectable (sensitivity 0.02 ppm) carbofuran residues. However only 8 of the soils contained greater than 0.5 ppm total carbofuran. The highest total carbofuran residue was 1.5 ppm, of which 0.31 ppm was 3-ketocarbofuran. In other soil samples 3-ketocarbofuran comprised 7-50% of the total carbofuran residue. No 3-hydroxycarbofuran was detected. The order of persistence of granular application of 3 insecticides as seed-furrow treatments was ethion greater than fonofos greater than carbofuran.

Carbofuran↗
PubMed1978

Extraction and liquid-solid chromatography cleanup procedures for the direct analysis of four pyrethroid insecticides in crops by gas--liquid chromatography.

The extraction of four pyrethroid insecticides, fenpropanate (WL 41706, S-3206), permethrin (WL 43479, FMC-33297, PP 557, NRDC-143), cypermethrin (WL 43467, NRDC 149), and fenvalerate (WL 43775, S-5602) from carrots, tomatoes celery, and onions with acetone followed by extraction of the resulting acetone--water mixture with hexane, was investigated and found suitable for residue analysis. The elution of the four materials from two types of silica and alumina absorbents with mixtures of organic solvents of varying polarity was examined. The elution patterns and recoveries from silica gel, aluminum oxide, and water deactivated Florisil indicated potential utility in cleanup. Florisil was found to provide cleanup for asparagus, carrots, tomatoes, tobacco, and onions permitting analyses to less than 0.01 ppm for most of the insecticides by electron capture gas--liquid chromatography, at extract concentrations of 1 g/ml. The other adsorbents, singly or in combination, were found to provide the cleanup required for radishes and those cases involving other crops where Florisil cleanup was insufficient.

Chromatography, Gas↗
PubMed1978

Radionuclide toxicity in cultured mammalian cells: elucidation of the primary site of radiation damage.

Synchronized suspension cultures of Chinese hamster ovary cells (CHO) were labeled with various doses of 3H-thymidine or 125I-iododeoxyuridine to evaluate the cytocidal effects of intranuclear radionuclide decay. Damage produced by radionuclide decay outside the cell nucleus was studied on cells exposed to 125I labeled, monovalent concanavalin A. After labeling, the cells were resynchronized in G1-phase and incubated for 36 h at 4 degrees C to permit dose accumulation. Cell lethality was evaluated by the standard colony assay. Based on radionuclide incorporation data, cellular dimensions, and subcellular radionuclide distributions, the cumulative dose to whole cells, cell nuclei, and cellular cytoplasm was calculated from the known decay properties of 3H and 125I. As expected, DNA associated 125I (LD50: 60 decays/cell; 45 rad) was much more toxic to CHO cells than 3H (LD50: 1350 decays/cell; 380 rad) 380 rad) or external X-irradiation (LD50: 330 rad). In contrast, membrane associated 125I was surprisingly non-toxic (LD50: 19 600 decays/cell). At 19 600 decays/cell the dose to the cell membrane was approximately 52 krad and the overlap dose into the cytoplasm was about 2470 rad. Even at these high dose levels, membrane damage or cytoplasmic damage apparently did not contribute significantly to radiation induced cell death. With 19 600 decays on the plasma membrane the CHO nuclei received an overlap dose of about 410 rad. As can be seen from the LD50 data for 3H and X-rays, a nuclear dose of 410 rad should be sufficient to account for 50% cell death. These findings indicate that, although intranuclear decay by electron capture is extremely destructive, identical decay events in the plasma membrane cause only minimal cell damage. This parallels our earlier studies on 67Ga labeled leukemia cells which showed that electron capture decay in the cytoplasm is also highly ineffective in killing mammalian cells. It therefore appears that radiation-induced cell lethality in dividing mammalian cells results primarily from nuclear damage. Cytoplasmic or membrane contributions to radiation-induced cell death, if any, must be minimal. By implication, these findings refute the enzyme release hypothesis and similar theories designed to explain mitotic death in terms of cytoplasmic or membrane damage rather than nuclear damage.

Animals↗
PubMed1976

Insecticide and nutrient transport in water, related to agricultural land use of a stream basin in Ontario, Canada.

Transport by stream water of insecticides and nutrients in Big Creek, Norfolk County, Ontario, Canada, was examined by combining concentrations of substrates with flow data. Big Creek has its headwaters in dairy cattle country, its central basin area is mainly devoted to tobacco growing, and its lower reaches contain mixed farming, corn and vegetables, etc., before it flows into Lake Erie. Three sampling sites were chosen to represent these 3 different land uses. Generally concentrations of substrates in the water were quite uniform at the 3 sites resulting in transport of quantities in proportion to stream flow. Certain anomalies occurred and are discussed. The 2 chief insecticides found were DDT and dieldrin. Analyses for potassium, calcium and magnesium indicated that these nutrient losses into the stream were area-rather than usage-dependent. Midseason variations in loss of nitrogen and phosphorus may be the result of agricultural practices in the three areas represented in this study. The largest quantities of all nutrients lost occurred early in the season before crops were established.

Agriculture↗
PubMed1975

Rdiotoxicity of intracellular 67Ga, 125I and 3H. Nuclear versus cytoplasmic radiation effects in murine L1210 leukaemia.

L1210 leukaemia cells were labelled with various doses of 67Ga-citrate, 3H-thymidine, or 125I-iododeoxyuridine to evaluate the cytocidal effects of the intracellular decay of the three radionuclides. Based on radioisotope incorporation data, cellular dimensions, and intracellular radioisotope distributions (3H and 125I intranuclear, 67Ga cytoplasmic) the rates of deposition of cellular, nuclear, and cytoplasmic energy were calculated. In terms of energy absorption/cell, 67Ga (LD50: 2250 keV/hr; 69 rad/hr) was much less toxic than either 3H (LD50: 325 keV/hr; 10 rad/hr) of 125I (LD50:50 keV/hr; 1-5 rad/hr). In terms of energy absorption/nuclesu, 67Ga and 3H produced almost identical effects (LD50: 230 versus 255 keV/hr; 22-2 versus 24-6 rad/hr), but 125I remained much more toxic (LD50: 40 keV/hr; 3-9 rad/hr). These findings indicate that, although decay by electron capture in the cell nucleus (125I) is highly destructive, the same type of decay occurring in the cytoplasm (67Ga) is ineffective in killing L1210 cells. An analysis of the data suggests that the cytotoxic effects of the three radioisotopes result exclusively from nuclear damage. Cytoplasmic absorption of radiation energy appears to contribute little, if anything, to the lethal effects of ionizing radiations.

Animals↗