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Triazine and metolachlor herbicide residues in farm areas of the Lower Fraser valley, British Columbia, Canada.

Crop soils, ditch sediments and water flowing from several Lower Fraser River (LFR) farm areas of British Columbia, Canada, to salmon tributary streams of that river were sampled in 2004-2005 to quantify for residues of triazine [atrazine, desethylatrazine (a transformation product of atrazine), propazine, and simazine] and metolachlor (a chloroacetamide) herbicides. Average concentrations [microg kg-1 dry weight (d.w.)] of triazine (10,110) and metolachlor (8,910) herbicides detected in crop soils at the start (May 2004, 2005) of the growing season were about 17 and 6 times, respectively, higher than those found for both herbicide groups during (June-Sept, 2004, 2005) the growing season. In contrast, mean concentrations (microg L-1) of triazines (0.092) and metolachlor (0.014) in permanent ditches adjacent to farms were about 7 and 28 times, respectively, lower at the start than during the growing season. Both herbicide groups in ditch sediments were detected only during the growing season at concentrations averaging about 315 microg kg-1 d.w. The risk potential of these herbicides for non-target aquatic organisms inhabiting permanent farm ditches contiguous to tributary streams of the LFR during the growing season is evaluated and discussed.

Acetamides↗

Application of automated mass spectrometry deconvolution and identification software for pesticide analysis in surface waters.

A new approach to surface water analysis has been investigated in order to enhance the detection of different organic contaminants in Nathan Creek, British Columbia. Water samples from Nathan Creek were prepared by liquid/liquid extraction using dichloromethane (DCM) as an extraction solvent and analyzed by gas chromatography mass spectrometry method in scan mode (GC-MS scan). To increase sensitivity for pesticides detection, acquired scan data were further analyzed by Automated Mass Spectrometry Deconvolution and Identification Software (AMDIS) incorporated into the Agilent Deconvolution Reporting Software (DRS), which also includes mass spectral libraries for 567 pesticides. Extracts were reanalyzed by gas chromatography mass spectrometry single ion monitoring (GC-MS-SIM) to confirm and quantitate detected pesticides. Pesticides: atrazine, dimethoate, diazinone, metalaxyl, myclobutanil, napropamide, oxadiazon, propazine and simazine were detected at three sampling sites on the mainstream of the Nathan Creek. Results of the study are further discussed in terms of detectivity and identification level for each pesticide found. The proposed approach of monitoring pesticides in surface waters enables their detection and identification at trace levels.

Automation↗

Pesticide contamination of ground water in the United States--a review.

Over 70 pesticides have been detected in ground water. Aldicarb and atrazine along with the soil fumigants EDB and DCP and DBCP have been the pesticides most frequently detected in ground water. Atrazine concentrations have been correlated with high nitrate concentrations. The triazine herbicides, simazine and cyanazine, have also been detected in ground water. The annual amount of recharge, soil type, depth of aquifer from the surface, nitrate contamination and soil pH are important field parameters in determining ground-water contamination potential by pesticides. Pesticide leaching is reduced by proper choice of crop rotation, increasing pesticide application efficiency, and integrated pest management.

Acetamides↗

Development of sampling and analytical methods for concerted determination of commonly used chloroacetanilide, chlorotriazine, and 2,4-D herbicides in hand-wash, dermal-patch, and air samples.

Sampling and analytical methods were developed for commonly used chloroacetanilide, chlorotriazine, and 2,4-D herbicides in hand washes, on dermal patches, and in air. Eight herbicides selected for study were alachlor, atrazine, cyanazine, 2,4-dichlorophenoxyacetic acid (2,4-D), metolachlor, simazine, and two esters of 2,4-D, the 2-butoxyethyl ester (2,4-D, BE) and the 2-ethylhexyl ester (2,4-D, EH). The hand-wash method consisted of shaking the worker's hand in 150 mL of isopropanol in a polyethylene bag for 30 seconds. The dermal-patch method entailed attaching a 10-cm x 10-cm x 0.6-cm polyurethane foam (PUF) patch to the worker for exposure; recovery of the herbicides was achieved by extraction with 40 mL of isopropanol. The air method involved sampling with an OVS-2 tube (which contained an 11-mm quartz fiber filter and two beds of XAD-2 resin) and recovery with 2 mL of 10:90 methanol:methyl t-butyl ether. Analysis of each of the three sample types was performed by gas chromatography with an electron-capture detector. Diazomethane in solution was employed to convert 2,4-D as the free acid to the methyl ester in each of the three methods for ease of gas chromatography. Silicic acid was added to sample solutions to quench excess diazomethane. Limits of detection for all eight herbicides were matrix-dependent and, generally, less than 1 microgram per sample for each matrix. Sampling and analytical methods met NIOSH evaluation criteria for all herbicides in hand-wash samples, for seven herbicides in air samples (all herbicides except cyanazine), and for six herbicides in dermal-patch samples (all herbicides except cyanazine and 2,4-D). Speciation of 2,4-D esters and simultaneous determination of 2,4-D acid were possible without losses of the esters or of other herbicides (acetanilides and triazines) being determined.

2,4-Dichlorophenoxyacetic Acid↗

Pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls in transport in two atlantic coastal plain tributaries and loadings to Chesapeake Bay.

Concentrations of current-use pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine (OC) insecticides were determined above the reach of tide in the Chesterville Branch and Nanticoke River on the eastern shore of Chesapeake Bay during base-flow and storm-flow hydrologic regimes to evaluate mass transport to Chesapeake Bay. The two rivers monitored showed relatively high concentrations of atrazine, simazine, alachlor, and metolachlor in comparison to previously investigated western shore tributaries, and reflected the predominant agricultural land use in the eastern shore watersheds. The four current use pesticides showed the greatest seasonal contribution to annual loadings to tidal waters of Chesapeake Bay from the two rivers, and the relative order of annual loadings for the other contaminant classes was PAHs > PCBs > OC insecticides. Annual loadings normalized to the landscape areas of selected Chesapeake Bay watersheds showed correlations to identifiable source areas, with the highest pesticide yields (g/km2/yr) occurring in eastern shore agricultural landscapes, and the highest PAH yields derived from urban regions.

Agriculture↗

9,10-Anthraquinone Reduces the Photosynthetic Efficiency of Oscillatoria perornata and Modifies Cellular Inclusions.

The natural compound 9,10-anthraquinone was found to inhibit the growth of the musty odor-producing cyanobacterium Oscillatoria perornata at a low concentration (1 µM) in previous laboratory studies. In this study, the mode of action of 9,10-anthraquinone was investigated by observing ultrastructural changes in O. perornata and by monitoring chlorophyll fluorescence as an indicator of photosynthetic efficiency. Results indicate that 9,10-anthraquinone inhibits photosynthetic electron transport, probably at PSII, and thereby affects growth. Moreover, 9,10-anthraquinone treatment caused thylakoid disorganization and reduced the number of ribosomes in O. perornata. The thylakoid disorganization is identical to reported modification in a cyanobacterium treated with simazine, a PSII inhibitor.

Journal Article↗

Determination of triazines in water samples by high-performance liquid chromatography with diode-array detection.

Triazines are widely used herbicides that can be detected in the environment at trace level. A preconcentration step is necessary to determinate them before analysis. In this study, carbonaceous and polymeric adsorbents are compared with C18 for the solid-phase extraction of simazine, atrazine, and propazine in water samples in order to quantitate their levels by high-performance liquid chromatography using photodiode-array detection.

Chromatography, High Pressure Liquid↗

Atrazine disrupts the hypothalamic control of pituitary-ovarian function.

The chloro-S-triazine herbicides (i.e., atrazine, simazine, cyanazine) constitute the largest group of herbicides sold in the United States. Despite their extensive usage, relatively little is known about the possible human-health effects and mechanism(s) of action of these compounds. Previous studies in our laboratory have shown that the chlorotriazines disrupt the hormonal control of ovarian cycles. Results from these studies led us to hypothesize that these herbicides disrupt endocrine function primarily through their action on the central nervous system. To evaluate this hypothesis, we examined the estrogen-induced surges of luteinizing hormone (LH) and prolactin in ovariectomized Sprague-Dawley (SD) and Long-Evans hooded (LE) rats treated with atrazine (50-300 mg/kg/day, by gavage) for 1, 3, or 21 days. One dose of atrazine (300 mg/kg) suppressed the LH and prolactin surge in ovariectomized LE, but not SD female rats. Atrazine (300 mg/kg) administered to intact LE females on the day of vaginal proestrus was without effect on ovulation but did induce a pseudopregnancy in 7 of 9 females. Three daily doses of atrazine suppressed the estrogen-induced LH and prolactin surges in ovariectomized LE females in a dose-dependent manner, but this same treatment was without effect on serum LH and prolactin in SD females. The estrogen-induced surges of both pituitary hormones were suppressed by atrazine (75-300 mg/kg/day) in a dose-dependent manner in females of both strains evaluated after 21 days of treatment. Three experiments were then performed to determine whether the brain, pituitary, or both organs were the target sites for the chlorotriazines. These included examination of the ability of (1) the pituitary lactotrophs to secrete prolactin, using hypophyosectomized females bearing pituitary autotransplants (ectopic pituitaries); (2) the synthetic gonadotropin-releasing hormone (GnRH) to induce LH secretion in females treated with high concentrations of atrazine for 3 days; and (3) atrazine (administered in vivo or in vitro) to suppress LH and prolactin secretion from pituitaries, using a flow-through perifusion procedure. In conclusion, the results of these studies demonstrate that atrazine alters LH and prolactin serum levels in the LE and SD female rats by altering the hypothalamic control of these hormones. In this regard, the LE female appeared to be more sensitive to the hormone suppressive effects of atrazine, as indicated by the decreases observed on treatment-day 3. These experiments support the hypothesis that the effect of atrazine on LH and prolactin secretion is mediated via a hypothalamic site of action.

Animals↗

2-Chloro-s-triazine herbicides induce aromatase (CYP19) activity in H295R human adrenocortical carcinoma cells: a novel mechanism for estrogenicity?

There is increasing concern that certain chemicals in the environment can cause endocrine disruption in exposed humans and wildlife. Investigations of potential effects on endocrine function have been limited mainly to interactions with hormone receptors. A need exists for the development of alternate in vitro methods to evaluate chemicals for their potential to disturb various endocrine functions via other mechanisms. Our laboratory is using the human H295R adrenocortical carcinoma cell line to examine chemicals for their potential to interfere with the activity and/or expression of several key cytochrome P450 (CYP) enzymes involved in the biosynthesis of steroid hormones. In this report we demonstrated that the commonly used 2-chloro-s-triazine herbicides atrazine, simazine, and propazine dose-dependently (0-30 microM) induced aromatase (CYP19) activity to an apparent maximum of about 2.5-fold in H295R cells. Basal- and triazine-induced aromatase activity was completely inhibited by the irreversible aromatase inhibitor 4-hydroxyandrostenedione (100 microM). The triazines increased levels of CYP19 messenger ribonucleic acid (mRNA) between 1.5- and 2-fold. The time-response profile of the induction of aromatase activity and CYP19 mRNA by the triazines was similar to that by 8-bromo-cyclic adenosine monophosphate, a known stimulant of the protein kinase-A pathway that mediates the induction of aromatase in these cells. The observed induction of aromatase, the rate-limiting enzyme in the conversion of androgens to estrogens, may be an underlying explanation for some of the reported hormonal disrupting and tumor promoting properties of these herbicides in vivo.

8-Bromo Cyclic Adenosine Monophosphate↗

Alteration of catecholamines in pheochromocytoma (PC12) cells in vitro by the metabolites of chlorotriazine herbicide.

The effects of four major chlorotriazine metabolites on the constitutive synthesis of the catecholamines dopamine (DA) and norepinephrine (NE) were examined, using undifferentiated PC12 cells. NE release and intracellular DA and NE concentrations were quantified, for up to 24 h after initiation of treatment with different concentrations, ranging from 0 to 400 microM, of the metabolites hydroxyatrazine (HA), 2-amino-4-chloro-6-isopropylamino-s-triazine (deethylchlorotriazine), 2-amino-4-chloro-6-ethylamino-s-triazine (deisopropylchlorotriazine), and diaminochlorotriazine (DACT). Hydroxyatrazine significantly decreased intracellular DA and NE concentrations in a dose- and time-dependent manner. This metabolite also caused a significant inhibition of NE release from the cells. In contrast, deethylchlorotriazine and deisopropylchlorotriazine significantly increased intracellular DA concentration following exposure to 50-200 microM from 12 to 24 h. Intracellular NE was significantly reduced at these same concentrations of deethylchlorotriazine at 24 h while the concentration of NE in PC12 cells exposed to deisopropylchlorotriazine was not altered at any dosage or time point measured. NE release was decreased at 18 (200 microM) and 24 h (100 and 200 microM) following exposure to deethylchlorotriazine and at 24 h (100 and 200 microM) following deisopropylchlorotriazine. DACT, at the highest concentration (160 microM), significantly increased intracellular DA and NE concentrations at 18 and 24 h. NE release was also increased at 40-160 microM at 24 h. The viability of the PC12 cells was tested using the trypan blue exclusion method. Following 18 to 24 h of treatments with HA, cell viability was reduced 10-12% at the two higher concentrations (200 and 400 microM), but, with other metabolites, the viability was reduced by only 2 to 5% at the highest concentrations. These data indicate that HA affects catecholamine synthesis and release in PC12 cells in a manner that is similar to synthesis of atrazine and simazine. On the other hand, deethylchlorotriazine and deisopropylchlorotriazine altered catecholamine synthesis in a manner similar to that observed in the rat brain following in vivo exposure (i.e., increased DA and decreased NE concentration), whereas DACT appeared to produce an increase in NE release as well as in the intracellular DA and NE concentrations. Overall, these findings suggest that the catecholamine neurons may be a target for the chlorotriazines and/or their metabolites, that the metabolites produce a unique pattern of catecholamine response, and that all of the changes were seen within the same range of doses.

Animals↗

Perinatal exposure to the fungicide prochloraz feminizes the male rat offspring.

Prochloraz is a commonly used fungicide that has shown multiple mechanisms of action in vitro. It antagonizes the androgen and the estrogen receptors, agonizes the Ah receptor, and inhibits aromatase activity. In vivo prochloraz acts antiandrogenically in the Hershberger assay by reducing weights of reproductive organs, affecting androgen-regulated gene expressions, and increasing luteinizing hormone (LH) levels. The purpose of this study was to investigate reproductive toxic effects after exposure during gestation and lactation to prochloraz alone and a mixture of five pesticides (deltamethrin, methiocarb, prochloraz, simazine, and tribenuron-methyl). Prochloraz (30 mg/kg/day) or the mixture (20 mg/kg/day) was dosed to pregnant Wistar dams from gestational day (GD) 7 until postnatal day (PND) 16. Some dams were taken for cesarean section at GD 21, and others were allowed to give birth. Results showed that prochloraz and the mixture significantly reduced plasma and testicular testosterone levels in GD 21 male fetuses, whereas testicular progesterone was increased. Gestational length was increased by prochloraz. Chemical analysis of the rat breast milk showed that prochloraz was transferred to the milk. In males a significant increase of nipple retention was found, and the bulbourethral gland weight was decreased, whereas other reproductive organs were unaffected. In addition cytochrome P450 (CYP)1A activities in livers were induced by prochloraz, possibly as a result of Ah receptor activation. Behavioral studies showed that the activity level and sweet preference of adult males were significantly increased. Overall these results strongly indicate that prochloraz feminizes the male offspring after perinatal exposure, and that these effects are due, at least in part, to diminished fetal steroidogenesis.

Animals↗

Metabolism of the herbicide atrazine by Rhodococcus strains.

Rhodococcus strains were screened for their ability to degrade the herbicide atrazine. Only rhodococci that degrade the herbicide EPTC (s-ethyl-dipropylthiocarbamate) metabolized atrazine. Rhodococcus strain TE1 metabolized atrazine under aerobic conditions to produce deethyl- and deisopropylatrazine, which were not degraded further and which accumulated in the incubation medium. The bacterium also metabolized the other s-triazine herbicides propazine, simazine, and cyanazine. The N dealkylation of triazine herbicides by Rhodococcus strain TE1 was associated with a 77-kb plasmid previously shown to be required for EPTC degradation.

Atrazine↗

Arthrobacter aurescens TC1 metabolizes diverse s-triazine ring compounds.

Arthrobacter aurescens strain TC1 was isolated without enrichment by plating atrazine-contaminated soil directly onto atrazine-clearing plates. A. aurescens TC1 grew in liquid medium with atrazine as the sole source of nitrogen, carbon, and energy, consuming up to 3,000 mg of atrazine per liter. A. aurescens TC1 is metabolically diverse and grew on a wider range of s-triazine compounds than any bacterium previously characterized. The 23 s-triazine substrates serving as the sole nitrogen source included the herbicides ametryn, atratone, cyanazine, prometryn, and simazine. Moreover, atrazine substrate analogs containing fluorine, mercaptan, and cyano groups in place of the chlorine substituent were also growth substrates. Analogs containing hydrogen, azido, and amino functionalities in place of chlorine were not growth substrates. A. aurescens TC1 also metabolized compounds containing chlorine plus N-ethyl, N-propyl, N-butyl, N-s-butyl, N-isobutyl, or N-t-butyl substituents on the s-triazine ring. Atrazine was metabolized to alkylamines and cyanuric acid, the latter accumulating stoichiometrically. Ethylamine and isopropylamine each served as the source of carbon and nitrogen for growth. PCR experiments identified genes with high sequence identity to atzB and atzC, but not to atzA, from Pseudomonas sp. strain ADP.

Arthrobacter↗

Effect of herbicides on cellulose decomposition by Sporocytophaga myxococcoides.

The effects of 14 herbicides on cellulose decomposition by Sporocytophaga myxococcoides were studied by growing the organism in two different liquid cellulose-mineral salts media in the presence of the test agent and then quantitatively determining the residual cellulose. In the first medium, containing acid-hydrolyzed cellulose, anthrone reagent was used to determine residual carbohydrate. In the second medium, Gooch Pyrex fritted-glass crucibles were used to determine the amount of residual Whatman powdered cellulose. The herbicides used were Atrazine, Simazine, Dacthal, Diuron, Amiben, Banvel-D, Banvel-T,2,3,6-TBA, Dicryl, Maleic Hydrazide, Stam F-34, Zytron, Fenac, and Dalapon. Of these, Zytron appeared to be the most inhibitory to the test bacterium, and was the only compound exhibiting inhibition at a commonly used field rate of application (2 ppm).

Bacteria↗

Effects of pesticides on nitrite oxidation by Nitrobacter agilis.

The influence of pesticides on the growth of Nitrobacter agilis in aerated cultures and on the respiration of N. agilis cell suspensions and cell-free extracts was studied. Two pesticides, aldrin and simazine, were not inhibitory to growth of Nitrobacter, but five compounds [isopropyl N-(3-chlorophenyl) carbamate (CIPC), chlordane, 1,1-dichloro-2,2-bis (p-chlorophenyl) ethane (DDD), heptachlor, and lindane] prevented growth when added to the medium at a concentration of 10 mug/ml. Whereas CIPC and eptam prevented nitrite oxidation by cell suspensions, the addition of DDD and lindane resulted in only partial inhibition of the oxidation. Heptachlor and chlordane also caused only partial inhibition of oxidation, but were more toxic with cell-free extract nitrite oxidase. None of the pesticides inhibited the nitrate reductase activity of cell-free extracts, but most caused some repression of cytochrome c oxidase activity. Heptachlor was the most deleterious compound.

Bacterial Proteins↗

Atrazine chlorohydrolase from Pseudomonas sp. strain ADP: gene sequence, enzyme purification, and protein characterization.

Pseudomonas sp. strain ADP metabolizes atrazine to carbon dioxide and ammonia via the intermediate hydroxyatrazine. The genetic potential to produce hydroxyatrazine was previously attributed to a 1.9-kb AvaI DNA fragment from strain ADP (M. L. de Souza, L. P. Wackett, K. L. Boundy-Mills, R. T. Mandelbaum, and M. J. Sadowsky, Appl. Environ. Microbiol. 61:3373-3378, 1995). In this study, sequence analysis of the 1.9-kb AvaI fragment indicated that a single open reading frame, atzA, encoded an activity transforming atrazine to hydroxyatrazine. The open reading frame for the chlorohydrolase was determined by sequencing to be 1,419 nucleotides and encodes a 473-amino-acid protein with a predicted subunit molecular weight of 52,421. The deduced amino acid sequence matched the first 10 amino acids determined by protein microsequencing. The protein AtzA was purified to homogeneity by ammonium sulfate precipitation and anion-exchange chromatography. The subunit and holoenzyme molecular weights were 60,000 and 245,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography, respectively. The purified enzyme in H2(18)O yielded [18O]hydroxyatrazine, indicating that AtzA is a chlorohydrolase and not an oxygenase. The most related protein sequence in GenBank was that of TrzA, 41% identity, from Rhodococcus corallinus NRRL B-15444R. TrzA catalyzes the deamination of melamine and the dechlorination of deethylatrazine and desisopropylatrazine but is not active with atrazine. AtzA catalyzes the dechlorination of atrazine, simazine, and desethylatrazine but is not active with melamine, terbutylazine, or desethyldesisopropylatrazine. Our results indicate that AtzA is a novel atrazine-dechlorinating enzyme with fairly restricted substrate specificity and contributes to the microbial hydrolysis of atrazine to hydroxyatrazine in soils and groundwater.

Amino Acid Sequence↗

Cluster analysis of the dermal permeability and stratum corneum/solvent partitioning of ten chemicals in twenty-four chemical mixtures in porcine skin.

Assumptions based on absorption from single solvent systems may be inappropriate for risk assessment when chemical mixtures are involved. We used K-means and hierarchical cluster analyses to identify clusters in stratum corneum partitioning and porcine skin permeability datasets that are distinct from each other based on mathematical indices of similarity and dissimilarity. Twenty-four solvent systems consisting of combinations of water, ethanol, propylene glycol, methyl nicotinate and sodium lauryl sulfate were used with 10 solutes, including phenol, p-nitrophenol, pentachlorophenol, methyl parathion, ethyl parathion, chlorpyrifos, fenthion, simazine, atrazine and propazine. Identifying the relationships between solvent systems that have similar effects on dermal absorption formed the bases for hypotheses generation. The determining influence of solvent polarity on the partitioning data structure supported the hypothesis that solvent polarity drives the partitioning of non-polar solutes. Solvent polarity could not be used to predict permeability because solvent effects on diffusivity masked the effects of partitioning on permeability. The consistent influence of the inclusion of propylene glycol in the solvent system supports the hypothesis that over-saturation due to solvent evaporation has a marked effect on permeability. These results demonstrated the potential of using cluster analysis of large datasets to identify consistent solvent and chemical mixture effects.

Animals↗

Effect of endocrine disrupting chemicals on lipopolysaccharide-induced tumor necrosis factor-alpha and nitric oxide production by mouse macrophages.

Little is known about the development of infectious diseases during exposure to endocrine disrupting chemicals (EDCs), although several studies have reported on the effect of EDCs on the immune function of the human body. To assess the effect of EDCs on the development of infectious disease, we investigated the effect of eighteen possible EDCs on mouse macrophage production of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) in response to bacterial endotoxin in vitro and ex vivo. Of chemicals we examined, simazine, nitrofen, and benzyl butyl phthalate inhibited lipopolysaccharide (LPS)-induced TNF-alpha production by mouse macrophage cell line RAW 264 in vitro. Carbaryl, alachlor, nonylphenol, octylphenol, tributyltin, and triphenyltin inhibited LPS-induced NO production in vitro, whereas 2,4-dichlorophenoxy acetic acid and bisphenol A enhanced its production. Zineb and alachlor, on the other hand, enhanced LPS-induced TNF-alpha production by mouse peritoneal macrophages ex vivo, while alachlor inhibited LPS/interferon-gamma-induced NO production ex vivo. These results indicate that some EDCs exert modulatory activity on endotoxin-induced macrophage activation either positively or negatively, suggesting that these compounds may affect the development of infectious diseases. This is the first report that systematically compared the effect of EDCs on LPS action.

Animals↗