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At least 199 records · Page 11Linked to original sources
PubMed2006

Effects of some endocrine disruptors on the secretory and proliferative activity of the regenerating rat adrenal cortex.

The effects of some endocrine disruptors that possess estrogen-like activity on the secretion and growth of regenerating rat adrenal cortex have been investigated in ovariectomized (OVX) and sham-OVX rats. As reference groups, dexamethasone (Dx)-administered sham-OVX and 17beta-estradiol-administered OVX animals were used. Dx, estradiol and endocrine disruptors were subcutaneously injected daily at a dose of 3 nmoles/100 g for 10 consecutive days after surgery, and adrenal enucleation was performed on day 5 of the experiment. Dx and genistein significantly decreased corticosterone plasma concentration (as measured by RIA) in sham-OVX rats with regenerating adrenals, while other disruptors (eusolex, procymidone, linurone, resveratrol, bisphenol-A and and silymarin) were ineffective. Mitotic index (as assayed by the stachmokinetic method with vincristine) was not changed by either Dx or disruptors. Estradiol significantly increased and genistein significantly lowered corticosterone blood level in OVX rats; similar effects were induced in the mitotic index of regenerating adrenals, but the changes were not significant. Eusolex increased the mitotic index, without altering the level of circulating corticosterone. Collectively, our findings allow us to conclude that, of the endocrine disruptors tested, only genistein is able to suppress the secretory activity of regenerating adrenal cortex, this Dx-like effect being apparently unrelated to its estrogen-like activity, and only eusolex enhances the proliferation rate of regenerating adrenal, the effect being conceivably connected with its estrogen-like activity.

Adrenal Cortex↗
PubMedDate not supplied

Determining organohalides in animal fats using gel permeation chromatographic cleanup: repeatability study.

Evaluation of a previously published gel permeation chromatographic (GPC) procedure was undertaken to determine whether it can be used for additional organochlorine pesticides. After repeatability studies of many pesticides, the following compounds were approved for inclusion in the U.S. Department of Agriculture Domestic Residue Monitoring Program: coumaphos-S, stirophos, chlorpyrifos, ronnel, carbophenothion, chlorfenvinphos, phosalone, kepone, captan, linuron, and endosulfan I and II. Recoveries ranged from 54% for captan to 123% for ronnel. Ranges of CVs varied from 0-9.5% for carbophenothion to 7.1-47.7% for kepone. Although the minimum acceptable recovery of 50% was attained for all 12 pesticides, the anticipated CV of 20% was waived to include chlorpyrifos, endosulfan I and II, and kepone. For a multiresidue procedure involving approximately 40 compounds, these results were within the acceptable criteria.

Animals↗
PubMedDate not supplied

[Effect of pesticides on bacterial membranes].

The effect of pure preparation of ordram, fosalon, DDT, methoxychlorine, hydrel, dihydrel, 2,4-D, 2M-4C and of technical preparations of saturn, linuron, ronstar and keltan on the membrane functions (respiration and motility) of Azospirillum brasilense and Chromatium minutissimum cells and on malate and NADH oxidation by the isolated membranes of Micrococcus lysodeikticus was investigated. The effect varied from irreversible impairment to undetectable impairment of the measured activities depending on the type of bacteria and on the chemical used. The ordram induced permeability of the A. brasilense membranes without inhibition of the respiratory chain activity and selective inhibition of malate oxidase accompanied by stimulation of NADH oxidation in the M. lysodeikticus membranes indicates a possibility of ordram application as a regulator of bacterial metabolism.

Bacteria↗
PubMed1988

A potpourri of pesticide poisonings in Alberta in 1987.

Several instances of what turned out to be pesticide and herbicide poisonings were investigated by us in 1987. They did not all occur in Alberta; some were referred. In addition, this laboratory did not investigate all pesticide incidents referred to Alberta Agriculture, as another laboratory is normally involved when pesticides are suspected from the outset. Perfunctory case histories are given along with brief analytical methodology for our use of GC/MS as an investigative tool in toxicological examinations. Four cases of carbofuran poisonings, 6 of lindane (sometimes in conjunction with other poisons), and 1 each of picloram, phorate, chlordane and avitrol are reported. Linuron was also found on trees dying in a tree nursery.

Alberta↗
PubMedDate not supplied

Residues of insecticides, fungicides, and herbicides on Ontario-grown vegetables, 1980-1985.

Between 1980 and 1985, 354 composite vegetable samples representing 9 vegetable commodities were collected from farm deliveries to the market place in Ontario, Canada. All samples were analyzed for insecticides, 275 for fungicides, and 135 for herbicides. The analyses included organochlorine, organophosphorus, synthetic pyrethroid, and N-methylcarbamate insecticides; dithiocarbamate, acylalanine, phthalimide, dicarboximide, and other fungicides; and, chlorophenoxy acid, chlorobenzoic acid, bipyridilium, phenylurea, carbamate, and other herbicides. The commodities tested included asparagus, beans, carrots, cauliflower, cucumbers, onions, potatoes, sweet corn, and tomatoes. In most samples, pesticide residues were below the detection limits (i.e., 0.005 to 0.1 mg/kg), and most of the positive findings were a fraction (i.e., less than 1 to 20%) of the maximum residue limit (MRL) permitted for each commodity under the Canadian Food and Drugs Act and Regulations. A small number of samples had residues that exceeded the MRL, and these involved aldicarb and linuron on potatoes and chlorobromuron on carrots.

Fungicides, Industrial↗
PubMedDate not supplied

Multiresidue method for determining substituted urea herbicides in foods by liquid chromatography.

A method is described for determining substituted urea herbicides in foods. The residues are extracted from the product with methanol, and the food coextractives are removed by using solvent partitioning and Florisil column chromatography. The extract is analyzed using liquid chromatography with postcolumn photodegradation, chemical derivatization with orthophthalaldehyde, and spectrofluorometry. Recoveries were determined by spiking 8 different food products with 6 phenylureas--chlorbromuron, chloroxuron, diuron, fluometuron, linuron, and metobromuron--at 0.05 and 0.5 ppm. Three determinations were made at each level for each product. Average recovery at 0.05 ppm was 95% (with a standard deviation of 7.9%), and at 0.5 ppm, 98% (with a standard deviation of 6.9%).

Chromatography, Liquid↗
PubMedDate not supplied

Herbicidal treatments for control of Cannabis sativa L.

In order to test herbicides for the destruction of illicit stands of cannabis (Cannabis sativa L.) a series of commercially available herbicides were sprayed on glasshouse-grown plants having 2 to 6 leaves. The following herbicides caused complete kill or severe injury to cannabis plants: (a) herbicides with root and foliage activity--ametryn, atrazine, metribuzin, prometryn, terbutryne, diuron, fluometuron, linuron, methabenzthiazuron, phenobenzuron, ethofumesate, karbutilate, methazole and oxadiazon; and (b) foliar-acting herbicides with brief or no soil persistence--amitrole, bentazon, 2,4-D, diquat + paraquat, glyphosate and phenmedipham. In field experiments herbicides of the latter group, and ioxynil, metribuzin, and a MSMA-cacodylate mixture, caused death or severe damage to young cannabis plants. Glyphosate, ioxynil and bentazon destroyed developed cannabis plants. In glasshouse and field experiments the following herbicides applied to young cannabis plants caused marked deformations of stems, leaves and/or inflorescences: barban, butralin, dalapon, difenzoquat, dinitramine, diphenamid, IPC, napropamide, penoxalin, triffuralin, and U-27267.

Cannabis↗
PubMed1980

Herbicidal treatments for control of Papaver somniferum L.

Fifty-five commercially available herbicides were evaluated for possible use to destroy illicit opium poppy crops (Papaver somniferum). In the first stage, herbicides were sprayed on poppy plants grown in containers. The following compounds killed poppy plants: (a) herbicides with typical foliar activity--amitrole, bromoxynil, 2,4-D, glyphosate, ioxynil and paraquat; and (b) herbicides with root and foliar activity--the triazines ametryn, atrazine, metribuzin, prometryn, simazine and terbutryn; the substituted ureas benzthiazuron, chloroxuron, diuron, fluometuron, linuron, methabenzthiazuron, neburon and phenobenzuron; and the miscellaneous compounds karbutilate, methazole, oxadiazon and pyrazon. Severe but sublethal injury was caused by cycloate, EPTC, molinate, pobulate, cacodylate + MSMA, ethofumesate, perfluidone and phenmedipham. Abnormal development of vegetative or reproductive parts of the plant was induced by benefin, butralin, dinitramine, pendimethalin, trifluralin, diphenamid, napropamide, dalapon and propham. Efficient herbicides with negligible persistence in soil at the doses applied were evaluated on poppy plants in the field at various stages of growth. Small plants were severely injured by 2,4-D, killed rapidly by bromoxynil, ioxynil, paraquat (in mixture + diquat), and more slowly by glyphosate and metribuzin. The resistance to herbicides increased with the age of the poppy plant. Severe damage with partial kill of developed plants was obtained with bromoxynil, ioxynil, glyphosate, and paraquat + diquat; the last treatment produced the fastest effect.

Drug and Narcotic Control↗
PubMed1976

High-pressure liquid chromatographic analysis of urea herbicides in foods.

A method is described for the direct analysis of the urea herbicides linuron, monuron, diuron, chlorbromuron, fluometuron, chloroxuron, and fenuron in cabbage, corn, potatoes, turnip, and wheat at 0.01-1.0 ppm. The samples are extracted with acetone; the filtrate is partitioned with hexane-methylene chloride (1+1) followed by 2 other extractions with methylene chloride. The organic phases are dried and concentrated for column chromatographic cleanup on 2% deactivated Florisil. The column fractions are evaporated just to dryness and redissolved in 10 ml isooctane for high-pressure liquid chromatography on a 25 cm silica gel (5 mum) column. Isopropanol in isooctane is the mobile phase, and compounds are measured by ultraviolet absorption at 254 nm. Recoveries are greater than 80% in most cases. These results are confirmed by alkylation with sodium hydride-methyl iodide in dimethyl sulfoxide to form the methyl products which are analyzed by the same chromatographic system or by gas-liquid chromatography.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Determination of phenylurea herbicide residues in vegetables by liquid chromatography after gel permeation chromatography and Florisil cartridge cleanup.

A liquid chromatographic method for quantitative determination of 9 phenylurea herbicide residues (metoxuron, metobromuron, monolinuron, chlortoluron, isoproturon, diuron, linuron, chloroxuron, and neburon) in potatoes, carrots, and mixed vegetables is described. Samples are extracted with acetone, partitioned with ethyl acetate-cyclohexane (50 + 50, v/v) and cleaned up by gel permeation chromatography with ethyl acetate-cyclohexane (50 + 50, v/v) as eluant. A small column (1 cm id) packed with Biobeads SX3 resin is used to reduce solvent consumption and analytical time. After solid-phase extraction on a Florisil cartridge, herbicide residues are successfully separated on a C18 column by gradient elution and determined by UV detection at 242 nm. Average recoveries of 9 compounds from different samples range from 70 to 98% at 0.010 and 0.100 mg/kg fortification levels. Quantitation limits are 0.010 mg/kg.

Chromatography, Gel↗
PubMed1999

Electrically driven microseparation methods for pesticides and metabolites. II: on-line and off-line preconcentration of urea herbicides in capillary electrochromatography.

Capillary electrochromatography (CEC) was introduced to the separation of nine important urea herbicides using octadecyl-silica (ODS) capillary columns that were specially designed to allow the realization of a relatively strong electroosmotic flow (EOF) and, in turn, fast separations. The ODS stationary phase was intentionally prepared to have a low surface coverage in octadecyl ligands in order to ensure a strong EOF. This ODS stationary phase of low surface coverage exhibited the usual reversed-phase chromatographic behavior as was manifested by the linearity of plots of log kappa versus the percent organic modifier in the mobile phase. The nature of the organic modifier of the mobile phase influenced the order of elution as well as the separation efficiency of the nine urea herbicides. Mobile phases containing acetonitrile yielded higher separation efficiency (by a factor of 1.5) than methanol-containing mobile phases. This was attributed to the higher mass transfer resistances of the solute in and out of the pores in the presence of the more viscous methanol-containing mobile phases. Due to the relatively strong affinity of the urea herbicides to the ODS stationary phase, on-line preconcentration consisting of prolonged injections allowed the determination of 10(-5) M urea herbicide samples using a UV detector without sacrificing separation efficiency. This was further decreased to 10(-7) M when the prolonged injection was preceded by the injection of a plug of water. The plug of water (the more retentive mobile phase) brought about an enhanced accumulation of the dilute samples into a narrow band at the inlet of the CEC column. When this on-column sample enrichment approach was combined with an off-line sample preconcentration step, which consisted of a solid-phase extraction process, ultra dilute samples of 10(-10) M (0.1 ppb) could be detected.

Chromatography, High Pressure Liquid↗
PubMed1987

Gas chromatography mass spectrometry of some thermally labile urea pesticides.

The application of gas chromatography/mass spectrometry to three thermally labile phenylurea pesticides is reported. Using alcohols as solvents the decomposition of the pesticides is followed by a reaction in which esters of N-(3,4-dichlorophenyl)carbamic acid are formed. As these reactions occur during the gas chromatographic analysis, it is the esters which are identified in the mass spectrometer. The methyl ester is itself a pesticide so an erroneous conclusion about the original pesticide could be reached when methanol is the solvent.

Diuron↗
PubMed1977

[Studies on the embryotoxicity of monolinuron and buturon in NMRI-mice (author's transl)].

The acute LD50 in virginal NMRI-Mice was found to be 2528 mg/kg for monolinuron and 1791 mg/kg for buturon. Pregnant female mice of the NMRI strain were administered orally 25--1000 mg monolinuron/kg (I) and 100-400 mg buturon/kg (II) on days 6--15 of gestation and, during defined phases of fetal development (days 10--13 after conception), 500 mg I/kg and 350 mg II/kg. Following administration of 10 doses, an increase of postimplantative losses and clear retardation of development in the upper dose range from 100 mg I/kg and 300 mg II/kg as well as a dose-dependent increase of the rate of cleft palates could be observed. High doses of both substances given from day 6--15 of pregnancy produced minor numbers of wavy and fused ribs as well as hypoplasia of the upper jaw after application of monolinuron and exenteria and exencephaly after buturon. Administration of monolinuron between days 10 and 13 of gestation resulted a minor and that of buturon a clear increase of the number of cleft palates. To evaluate postnatal development 200 and 500 mg I/kg, and 200 and 300 mg II/kg were administered orally on days 6--15 of gestation. In the higher doses, both substances produced an increased mortality among the offspring up to 3 weeks after birth, and a clear increase of the rate of cleft palates.

Abnormalities, Drug-Induced↗