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PubMed2003

Pesticide degradation in a 'biobed' composting substrate.

Pesticides play an important role in the success of modern farming and food production. However, the release of pesticides to the environment arising from non-approved use, poor practice, illegal operations or misuse is increasingly recognised as contributing to water contamination. Biobeds appear to offer a cost-effective method for treating pesticide-contaminated waste. This study was performed to determine whether biobeds can degrade relatively complex pesticide mixtures when applied repeatedly. A pesticide mixture containing isoproturon, pendimethalin, chlorpyrifos, chlorothalonil, epoxiconazole and dimethoate was incubated in biomix and topsoil at concentrations to simulate pesticide disposal. Although the data suggest that interactions between pesticides are possible, the effects were of less significance in biomix than in topsoil. The same mixture was applied on three occasions at 30-day intervals. Degradation was significantly quicker in biomix than in topsoil. The rate of degradation, however, decreased with each additional treatment, possibly due to the toxicity of the pesticide mixture to the microbial community. Incubations with chlorothalonil and pendimethalin carried out in sterile and non-sterile biomix indicated that degradation, rather than irreversible adsorption to the matrix, was the main mechanism responsible for the reduction in recovered residues. Results from these experiments suggest that biobeds offer a viable means of treating pesticide waste.

Biodegradation, Environmental↗

PubMed1998

Osmotic effects as a factor modifying insecticide toxicity on Aedes and Artemia.

Euryhaline species are more tolerant of various insecticides under isosmotic conditions. Two euryhaline species, Aedes taeniorhynchus (Wiedemann) and Artemia sp., were exposed to four insecticides (aldicarb, dimethoate, imidacloprid, tebufenozide), under isosmotic and hyperosmotic conditions. Mortality under these two osmotic conditions was observed and compared to evaluate salinity as a contributing factor to insecticide toxicity. Artemia was more tolerant of all chemicals tested than A. taeniorhynchus under isosmotic conditions based on the percentage mortality observed. Mortality of Artemia under isosmotic conditions was dependent on the length of exposure; A. taeniorhynchus did not exhibit time dependence. Less mortality was observed in populations of both test species under isosmotic conditions compared with hyperosmotic conditions. However, the variation in mortality due to exposure to test chemicals was of greater magnitude in A. taeniorhynchus than Artemia. This result indicates that higher salinity is a greater stress on A. taeniorhynchus than Artemia when exposed to the test insecticides at the concentration ranges tested in this study.

Aedes↗

PubMed2002

Effects of currently used pesticides in assays for estrogenicity, androgenicity, and aromatase activity in vitro.

Twenty-four pesticides were tested for interactions with the estrogen receptor (ER) and the androgen receptor (AR) in transactivation assays. Estrogen-like effects on MCF-7 cell proliferation and effects on CYP19 aromatase activity in human placental microsomes were also investigated. Pesticides (endosulfan, methiocarb, methomyl, pirimicarb, propamocarb, deltamethrin, fenpropathrin, dimethoate, chlorpyriphos, dichlorvos, tolchlofos-methyl, vinclozolin, iprodion, fenarimol, prochloraz, fosetyl-aluminum, chlorothalonil, daminozid, paclobutrazol, chlormequat chlorid, and ethephon) were selected according to their frequent use in Danish greenhouses. In addition, the metabolite mercaptodimethur sulfoxide, the herbicide tribenuron-methyl, and the organochlorine dieldrin, were included. Several of the pesticides, dieldrin, endosulfan, methiocarb, and fenarimol, acted both as estrogen agonists and androgen antagonists. Prochloraz reacted as both an estrogen and an androgen antagonist. Furthermore, fenarimol and prochloraz were potent aromatase inhibitors while endosulfan was a weak inhibitor. Hence, these three pesticides possess at least three different ways to potentially disturb sex hormone actions. In addition, chlorpyrifos, deltamethrin, tolclofos-methyl, and tribenuron-methyl induced weak responses in one or both estrogenicity assays. Upon cotreatment with 17beta-estradiol, the response was potentiated by endosulfan in the proliferation assay and by pirimicarb, propamocarb, and daminozid in the ER transactivation assay. Vinclozolin reacted as a potent AR antagonist and dichlorvos as a very weak one. Methomyl, pirimicarb, propamocarb, and iprodion weakly stimulated aromatase activity. Although the potencies of the pesticides to react as hormone agonists or antagonists are low compared to the natural ligands, the integrated response in the organism might be amplified by the ability of the pesticides to act via several mechanism and the frequent simultaneous exposure to several pesticides.

Animals↗

PubMed1984

Cytogenetic and genetic effects of subchronic treatments with organophosphorus insecticides.

Male mice (Q strain) received 5 days a week for 7 weeks drinking water containing dichlorvos (2 ppm), dimethoate (0.6 ppm), malathion (8 ppm), methylparathion (0.15 ppm), or trichlorfon (0.5 ppm). At the end of the treatment, no chromosome damage was observed in bone marrow cells, spermatogonia, and primary spermatocytes. Dominant lethal mutation assays were performed to investigate the pre- and postimplantation foetal lethality. Only negative results were obtained.

Animals↗

PubMed1994

The effect of trichlorfon and other organophosphates on prenatal brain development in the guinea pig.

The organophosphates trichlorfon, dichlorvos, dimethoate, soman, triortho-cresyl phosphate (TOCP), and the diethoxy-analogue of trichlorfon (O,O-diethyl 2,2,2-trichloro-1-hydroxyethylphosphonate, ethyl-trichlorfon), were administered to guinea pigs between day 42 and 46 of gestation. When the offsprings were examined at birth, there was a severe reduction in brain weight in the case of trichlorfon and dichlorvos, but not after treatment with the other organophosphates. The reduction in weight was most pronounced for cerebellum, medulla oblongata, thalamus/hypothalamus and quadrigemina. The effect was less marked for cerebral cortex and hippocampus. Since soman, a potent anticholinesterase, and TOCP, an inhibitor of neuropathy target esterase, did not show any effects, this excludes that the brain hypoplasia can be caused by inhibition of these two enzymes. Further, the lack of effect with ethyl-trichlorfon has shed some light on the part of the trichlorfon molecule which could be involved in the formation of the hypoplasia. It is suggested that alkylation of DNA may be involved in the development of the lesion. The possible consequences for a teratogenic effect of trichlorfon and dichlorvos on humans are discussed.

Abnormalities, Drug-Induced↗

PubMed1980

Influence of selected pesticides on the microbial degradation of 14C-triallate and 14C-diallate in soil.

Degradation in soil of [allyl-2-14C]triallate and [carbonyl-14C]diallate herbicides, as affected by other selected pesticides, was studied in an incubation system that allowed recovery of 95 to 100% of added 14C. The amount and sequence of pesticide additions simulated field use in the protection of wheat (triallate) and sugar beets (diallate). Neither the rate nor the pattern of triallate degradation in soil was influenced by the following sequence of formulated pesticides: dinoseb acetate, (bentazon + dichlorprop + 2,4,5-T), 2,4-D, (chlorcholinchloride + cholinchloride), tridemorph, and thiophanate. Similarly, diallate degradation was unaffected by pyrazon, dimethoate, and thiophanate. The effect of azinphosmethyl was unclear. In contrast, chlorpyrifos reduced diallate degradation by approximately 14% relative to the occurring in the insecticide's absence. This effect was caused by chlorpyrifos and not its formulation components. Chlorpyrifos was also found to partially inhibit degradation of triallate in soil. Inhibition of neither herbicide was considered to be of ecological significance. Triallate, diallate, and thiophanate were applied at 1 microgram/g; all others were at 2 microgram/g.

Biodegradation, Environmental↗

PubMed1991

Selection of high-level abamectin resistance from field-collected house flies, Musca domestica.

Abamectin is a novel, highly promising insecticide with activity against many pests. To determine if resistance to abamectin could occur, we collected house flies from several New York dairies and selected them in the laboratory. Resistance developed rapidly and to a high level (36 or greater than 60,000-fold, depending upon test technique and/or adjuvant) that could not be overcome by the synergists piperonyl butoxide or S,S,S-tributylphosphorotrithioate. There was no increase in (cross)resistance to crotoxyphos, dichlorvos, dimethoate, tetrachlorvinphos, permethrin, dieldrin or lindane following abamectin selection. Our results suggest the potential for abamectin resistance is high, at least in house flies, and that the judicious use of abamectin will be needed to prolong its usefulness as an insecticide.

Animals↗

PubMed1992

Plasma concentrations of pralidoxime methylsulphate in organophosphorus poisoned patients.

Using pharmacokinetic data from healthy human volunteers in a bicompartmental pharmacokinetic model, a repeated dose scheme for pralidoxime methylsulphate (Contrathion) was developed producing plasma levels remaining above the assumed "therapeutic concentration" of 4 mg.l-1. Using the same data, it was found that a concentration of 4 mg.l-1 could also be obtained by a loading dose of 4.42 mg.kg-1 followed by a maintenance dose of 2.14 mg.kg-1.h-1. In order to study the pharmacokinetic behaviour of pralidoxime in poisoned patients, this continuous infusion scheme was then applied in nine cases of organophosphorus poisoning (agents: ethyl parathion, ethyl and methyl parathion, dimethoate and bromophos), and the pralidoxime plasma levels were determined. The mean plasma levels obtained in the various patients varied between 2.12 and 9 mg.l-1. Pharmacokinetic data were calculated, giving a total body clearance of 0.57 +/- 0.27 l.kg-1.h-1 (mean +/- SD), an elimination half-life of 3.44 +/- 0.90 h, and a volume of distribution of 2.77 +/- 1.45 l.kg-1.

Dose-Response Relationship, Drug↗

PubMed1995

A comparison of trimedoxime, obidoxime, pralidoxime and HI-6 in the treatment of oral organophosphorus insecticide poisoning in the rat.

This study summarizes the results of examination of acute oral toxicity of 26 organophosphorus insecticides in rats. The effectiveness of trimedoxime, obidoxime, pralidoxime and HI-6, given with atropine and diazepam, was tested in the treatment of poisoning with 2 LD50 of the insecticides. It was shown that the oximes were potent antidotes in poisoning with phosphate insecticides. Obidoxime, pralidoxime and HI-6 had low effectiveness in the treatment of poisoning with phosphonates and phosphorothiolates. However, none of the oximes was an effective antidote in poisoning with dimethoate and pyridafenthion. Trimedoxime was the most effective oxime in the treatment of insecticide poisoning, being successful especially at the lowest tested doses.

Administration, Oral↗

PubMed1999

Dimethylphosphoryl-inhibited human cholinesterases: inhibition, reactivation, and aging kinetics.

Human poisoning by organophosphates bearing two methoxy groups, e.g. by malathion, paraoxon-methyl, dimethoate and oxydemeton-methyl, is generally considered to be rather resistant to oxime therapy. Since the oxime effectiveness is influenced not only by its reactivating potential but also by inhibition, aging and spontaneous reactivation kinetics, experiments were performed with human acetyl- (AChE) and butyrylcholinesterase (BChE) to determine the respective kinetic constants. The efficacy of obidoxime in reactivating dimethylphosphoryl-AChE was 40, 9 and 3 times higher than of HI 6, pralidoxime and HLö 7, respectively. Aging (t1/2 3.7 h) and spontaneous reactivation (t1/2 0.7 h) occurred concomitantly, with the portion of the aged enzyme being dependent on the presence of excess inhibitor. Calculation of steady-state AChE activity in the presence of inhibitor and oxime revealed that obidoxime was superior to pralidoxime. In addition, organophosphate concentrations up to 10(-6) M (paraoxon-methyl) and 10(-4) M (oxydemeton-methyl) could be counteracted at clinically relevant oxime concentrations (10 microM). These data indicate that oximes may effectively reactivate human dimethylphosphoryl-AChE. Failure of oximes may be attributed to megadose intoxications and to prolonged time intervals between poison uptake and oxime administration. The potency of the oximes to reactivate dimethylphosphoryl-BChE was much lower and the spontaneous reactivation slower (t1/2 9 h), while aging proceeded at a comparable rate. Thus, BChE activity determination for diagnosis and therapeutic monitoring may give no reliable information on AChE status.

Acetylcholinesterase↗

PubMed2002

Pesticide toxicity assessment using an electrochemical biosensor with Pseudomonas putida and a bioluminescence inhibition assay with Vibrio fischeri.

Two different toxicity tests, an electrochemical biosensor Cellsense and a bioluminescence inhibition assay ToxAlert were performed in order to establish and compare the acute toxicity responses of different types of raw and spiked water for a selected group of pesticides. The selected compounds were endosulfan, chlorfenvinphos, dimethoate, fenamiphos, ametryn, deltamethrin and alpha-cypermethrin; all of them are used in large quantities for agricultural purposes. In the first step, the study of the toxicity responses for each individual pesticide with Milli-Q water was carried out. Next, the toxic responses of different mixtures of these pesticides in different water matrices, i.e., Milli-Q water, surface water, groundwater and wastewater were studied in order to evaluate (i) device advantages and limitations for the toxicity evaluation of real environmental samples, (ii) antagonistic or synergistic effects and (iii) the influence of the water matrices. The survey of pesticides in real samples was carried out using a combined method involving both chemical analysis and toxicity bioassays. Chemical analysis involved the use of solid-phase micro-extraction (SPME) followed by gas chromatography with electron capture detection (GC/ECD) or thermoionic specific detection (GC/TSD) with mass spectrometric confirmation (GC/MS).

Biosensing Techniques↗

PubMed2005

Comparative sublethal toxicity of nine pesticides on olfactory learning performances of the honeybee Apis mellifera.

Using a conditioned proboscis extension response (PER) assay, honeybees (Apis mellifera L.) can be trained to associate an odor stimulus with a sucrose reward. Previous studies have shown that observations of conditioned PER were of interest for assessing the behavioral effects of pesticides on the honeybee. In the present study, the effects of sublethal concentrations of nine pesticides on learning performances of worker bees subjected to the PER assay were estimated and compared. Pesticides were tested at three concentrations. The highest concentration of each pesticide corresponded to the median lethal dose value (48-h oral LD50), received per bee and per day, divided by 20. Reduced learning performances were observed for bees surviving treatment with fipronil, deltamethrin, endosulfan, and prochloraz. A lack of behavioral effects after treatment with lambda-cyalothrin, cypermethrin, tau-fluvalinate, triazamate, and dimethoate was recorded. No-observed-effect concentrations (NOECs) for the conditioned PER were derived for the studied pesticides. Our study shows that the PER assay can be used for estimating sublethal effects of pesticides on bees. Furthermore, comparisons of sensitivity as well as the estimation of NOECs, useful for regulatory purposes, are possible.

Animals↗

PubMed1993

Study of multi-residue methods for the determination of selected pesticides in groundwater.

A study of different multi-residue methods for the determination of pesticides in groundwater samples was made by comparing several extraction procedures which included liquid-liquid partitioning and solid-phase extraction. The effect of extraction conditions, such as organic solvent, volume ratio, addition of NaCl and pH, were studied. Recoveries, detection and determination limits, as well as precision of the procedures for several replicates were obtained. The pesticides studied were selected taking into account their application on citrus groves in the Plana of Castellon (Spain). These compounds included organochlorine pesticides (lindane, dicofol, chlorfenson and tetradifon), organophosphorous (dimethoate, fenitrothion and methidathion) and phenoxyacid herbicides (MCPA and 2,4-D). Analysis were carried out by high resolution gas chromatography using a dual detection system (ECD and NPD), as well as by high performance liquid chromatography (HPLC) with UV detection. This procedure was applied to several groundwater samples from Castellon province (Spain).

Chromatography, Gas↗

PubMed1995

The study of interactive effects of pollutants: a biomarker approach.

Biochemical biomarkers, such as inhibition of serum butyryl cholinesterase (BuChE) and brain acetyl cholinesterase (AChE), have been useful in studies of interactive effects of pesticides in birds. Examples of interactions due to increased activation or decreased detoxication are reviewed. Studies have shown that hybrid red-legged partridges (Alectoris rufa cross) pretreated with the inducing ergosterol biosynthesis inhibiting (EBI) fungicide, prochloraz, were more sensitive to the toxic effects of the organophosphorous (OP) insecticide, malathion, than controls. A dose of 90 mg/kg prochloraz produced greater inhibition at 1, 4 and 24 h following oral administration of 50 mg/kg malathion, compared to corn oil controls. Pigeons (Columba livia) given 180 or 90 mg/kg prochloraz showed greater inhibition of BuChE activity following malathion administration than did control birds. Starlings (Stumus vulgaris), however, appeared not to be induced by 180 or 300 mg/kg prochloraz, and no difference in BuChE activity following dosing with malathion was apparent in comparison with controls. Other EBIs and OP combinations have been investigated in the partridge. Birds pretreated with prochloraz showed a trend towards greater inhibition of serum BuChE activity at most time points following dosing with the OPs dimethoate and chlorpyriphos. Birds pretreated with the EBI penconazole showed significantly greater inhibition of serum BuChE activity at 1, 4 and 24 h after malathion administration than did controls. The mechanism of increased activation of malathion due to induction of cytochrome P-450 by prochloraz is reviewed. In the case of interactions due to inhibition of detoxication, inhibition of brain AChE activity was a useful biochemical biomarker.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Toxicity of four pesticides on the fingerlings of Indian major carps Labeo rohita, Catla catla, and Cirrhinus mrigala.

Fingerlings of Labeo rohita, Catla catla, and Cirrhinus mrigala were exposed to selected doses of four commonly used pesticides carbofuran, DDT, dimethoate, and Meta-Systox for a period up to 30 days to determine relative toxicological effects, LC50 values for 96 hr, maximum acceptable tolerant concentration, and application factor. The use of early life history tests has been emphasized for toxicological assessments.

Animals↗

PubMed1981

Induction of sister-chromatid exchanges and cell cycle delay in cultured mammalian cells treated with eight organophosphorus pesticides.

Induction of sister-chromatid exchanges (SCE) and cell cycle delay in Chinese hamster cell line V79 after treatment with 8 organophosphorus pesticides (OPP) were studied. In addition, these effects were also studied using 1 of the 8 OPP in 2 human lymphoid cell lines. In V79 cells, 6 of the 8 OPP induced significant increase of frequencies of SCE and all the OPP induced various degrees of cell cycle delay. The 6 OPP in decreasing order of SCE induction are methylparathion, demeton, trichlorfon, dimethoate, malathion and methidathion. The 2 OPP that had no effect on SCE are diazion and disyston. The extents of induced cell cycle delay are generally related to the OPP concentrations but does not necessarily correlate with the extent of induction of SCE among the OPP studied. The results of studies on the effect of methyl-parathion on SCE and cell cycle delay in 2 human cell lines showed that both lines had significant and dose-dependent increase of SCE frequencies similar to those observed in V79 cells. In contrast to V79 cells, however, cell cycle delay was not as prominent in the human lines at comparable doses. These studies indicated that 5-bromodeoxyuridine labeling for analyzing SCE and cell cycle delay is a very sensitive method in assessing mutagenic potential of environmental compounds especially those that are highly toxic to and rapidly degradable in mammalian cells such as OPP.

Animals↗

PubMedDate not supplied

Cytokinetic and cytogenetic effects of some agricultural chemicals on human lymphoid cells in vitro: organophosphates.

In the present study, cytotoxic, cytostatic and cytogenetic effects of a number of organophosphate pesticides on human lymphoid cells (LAZ-007) in culture have been examined. Cytotoxic effects were dose related and often led to extensive cell kill. The pronounced effects of various organophosphates on the cell-cycle traverse were shown in data based on the enumeration of M1 and M3 metaphases after incubation of cells with BrdU. In cells incubated with 20 micrograms/ml of the various chemicals, the number of M1 metaphases ranged from 6% (R-1303) to 18% (Azodrin) compared to no M1 metaphases in control cultures. The number of M3s in cultures treated with 20 micrograms/ml of the various chemicals tested varied from 0% (Phosdrin) to 7% (parathion) as compared to 17% in control cultures. 11 out of the 14 organophosphates tested, significantly increased the SCE frequency. Of the 9 chemicals tested after metabolic activation by liver microsomal S9 preparation, significant increases in SCE frequency were seen in diazinon-, dimethoate-, Dursban- and Phosdrin-treated cells.

Animals↗

PubMed1989

Frequencies of chromosomal aberrations in smokers exposed to pesticides in cotton fields.

Blood samples were collected from 50 smokers who were exposed to the pesticides DDT, BHC, endosulfan, malathion, methyl parathion, monocrotophos, quinolphos, dimethoate, phosphomidon, cypermethrin and fenvelrate. Samples were also collected from 20 non-smokers (control I) and 27 smokers (control II) who were unexposed to pesticides. Control II showed a significant increase in chromosomal aberrations when compared to control I. There was a significant increase in total chromosomal aberrations in smokers exposed to pesticides when compared to unexposed populations.

Adult↗