Home About us Contact
|
Home About us Contact | ||
|
|
||
Atrazine
Terms modified by Atrazine Selected AbstractsUtilization of a Copper Solid Amalgam Electrode for the Analytical Determination of AtrazineELECTROANALYSIS, Issue 22 2005Djenaine De, Souza Abstract A copper solid amalgam electrode was prepared and used for the voltammetric determination of atrazine in natural water samples by square wave voltammetry. This electrode is a convenient substitute for the hanging mercury electrode since it is selective, sensitive, reliable and inexpensive and presents low toxicity characteristic. The detection limit of atrazine obtained in pure water (laboratory samples) was shown to be lower than the maximum limit of residue established for natural water by the Brazilian Environmental Agency. The relative standard deviation for 10 different measurements was found to be only 3.98% in solutions containing 8.16×10,6,mol L,1 of atrazine. In polluted stream water samples, the recovery measurements were approximately 70.00%, sustaining the applicability of the proposed methodology to the analysis of atrazine in such matrices. [source] Atrazine increases the sodium absorption in frog (Rana esculenta) skinENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2006Giuseppe Cassano Abstract The presence of atrazine in agricultural sites has been linked to the decline in amphibian populations. The efforts of the scientific community generally are directed toward investigating the long-term effect of atrazine on complex functions (reproduction or respiration), but in the present study, we investigated the short-term effect on the short-circuit current (ISC), a quantitative measure of the ion transport operated by frog (Rana esculenta) skin. Treatment with 5 ,M atrazine (1.08 mg/L) does not affect the transepithelial outfluxes of [14C]mannitol or [14C]urea; therefore, atrazine does not damage the barrier properties of frog skin. Atrazine causes a dose-dependent increase in the short-circuit current, with a minimum of 4.64 ± 0.76 ,A/cm2 (11.05% ± 1.22%) and a maximum of 12.7 ± 0.7 ,A/cm2 (35% ± 2.4%) measured at 10 nM and 5 ,M, respectively. An increase in ISC also is caused by 5 ,M ametryne, prometryn, simazine, terbuthylazine, or terbutryn (other atrazine derivatives). In particular, atrazine increases the transepithelial 22Na+ influx without affecting the outflux. Finally, stimulation of ISC by atrazine is suppressed by SQ 22536, H89, U73122, 2-aminoethoxydiphenyl borate, and W7 (blockers of adenylate cyclase, protein kinase A, phospholipase C, intracellular Ca2+ increase, and calmodulin, respectively), whereas indomethacin and calphostin C (inhibitors of cyclooxygenase and protein kinase C, respectively) have no effect. [source] Increased toxicity to invertebrates associated with a mixture of atrazine and organophosphate insecticidesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Troy D. Anderson Abstract This study examined the joint toxicity of atrazine and three organophosphate (OP) insecticides (chlorpyrifos, methyl parathion, and diazinon) exposed to Hyalella azteca and Musca domestica. A factorial design was used to evaluate the toxicity of binary mixtures in which the lethal concentration/lethal dose (LC1/LD1, LC5/LD5, LC15/LD15, and LC50/LD50) of each OP was combined with atrazine concentrations of 0, 10, 40, 80, and 200 ,g/L for H. azteca and 0, 200, and 2,000 ng/mg for M. domestica. Atrazine concentrations (>40 ,g/L) in combination with each OP caused a significant increase in toxicity to H. azteca compared with the OPs dosed individually. Acetylcholinesterase (AChE) activity also was examined for the individual OPs with and without atrazine treatment. Atrazine in combination with each of the OPs resulted in a significant decrease in AChE activity compared with the OPs dosed individually. In addition, H. azteca that were pretreated with atrazine (>40 ,g/L) were much more sensitive to the OP insecticides compared with H. azteca that were not pretreated with atrazine before being tested. Topical exposure to atrazine concentrations did not significantly increase OP toxicity to M. domestica. The results of this study indicate the potential for increased toxicity in organisms exposed to environmental mixtures. [source] Atrazine-induced changes in aromatase activity in estrogen sensitive target tissuesJOURNAL OF APPLIED TOXICOLOGY, Issue 3 2008A. C. Holloway Abstract Atrazine (ATR) is a pesticide used widely throughout North America. Although not directly estrogenic, ATR treatment has been shown to increase aromatase activity in tumor cell lines. Thus, it is suggested that ATR can increase local tissue estrogen levels in estrogen sensitive target tissues through increased aromatase activity. Therefore the effect of ATR on aromatase activity was measured in human granulosa-lutein cell cultures, cells that abundantly express aromatase, and endometrial stromal cell (ESC) cultures, cells that do not express aromatase. Aromatase activity was quantified by the tritiated water method and the specificity of the assay was confirmed by co-incubation with 4-hydroxyandrostenedione, an irreversible inhibitor of the catalytic activity of aromatase. Aromatase activity in ATR treated (1,10 µm) granulosa-lutein cells was increased more than 2-fold compared with control cultures. There were no treatment related changes in cellular protein and thus it is suggested that the ATR-induced change in aromatase activity was not due to an increase in cell number. ATR-treatment had no effect on ESC aromatase activity at any concentration tested. Similarly, there was no effect of ATR treatment on human recombinant aromatase activity in our cell-free test system. Therefore it is concluded that µm concentrations of ATR can increase aromatase activity of human granulosa cells but not ESC and this effect is not elicited at the enzyme level. Copyright © 2007 John Wiley & Sons, Ltd. [source] Integrated modeling environment for statewide assessment of groundwater vulnerability from pesticide use in agriculture,PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2004Audra Eason Abstract Atrazine, a herbicide widely used for corn production in the Midwest, has been detected in groundwater of several states, and has been identified as a possible human carcinogen. With the widespread use of pesticides in crop production, and the frequent detection of these chemicals in groundwater, large-scale risk assessments would help water resource managers to identify areas that are more susceptible to contamination and implement practices to ameliorate the problem. This paper presents an integrated, visual and interactive system for predicting potential environmental risks associated with pesticide contamination at spatial scales ranging from fields to landscapes and regions. The interactive system extends the predictive ability of the Pesticide Root Zone Model Release 2.0 (PRZM-2) to a landscape and statewide scale through integration with a geographic information system (GIS), graphical user interface and environmental databases. Predictions of statewide (Iowa) vulnerability of groundwater from atrazine leaching below the unsaturated zone were made to demonstrate the utility of the system, and the results were used in risk assessment. In the example application, atrazine fate and transport were evaluated using long-term climatic data (1980,1989) in combination with several environmental databases (eg STATSGO soils database) and exposure risks were expressed in terms of the probability of the predicted pesticide concentrations exceeding the maximum contaminant level (MCL) for drinking water. The results indicate that the predicted pesticide concentrations were significantly lower than the EPA-established MCL. In addition to providing an interactive environment for landscape-level assessment of potential risks from pesticide leaching, the system significantly reduces the time and resources needed to organize and manipulate data for use with PRZM-2, and provides an analytical framework for evaluating groundwater-leaching impacts of pesticide management practices. Copyright © 2004 Society of Chemical Industry [source] Biodegradation of atrazine in transgenic plants expressing a modified bacterial atrazine chlorohydrolase (atzA) genePLANT BIOTECHNOLOGY JOURNAL, Issue 5 2005Lin Wang Summary Atrazine is one of the most widely used herbicides in the USA. Atrazine chlorohydrolase (AtzA), the first enzyme in a six-step pathway leading to the mineralization of atrazine in Gram-negative soil bacteria, catalyses the hydrolytic dechlorination and detoxification of atrazine to hydroxyatrazine. In this study, we investigated the potential use of transgenic plants expressing atzA to take up, dechlorinate and detoxify atrazine. Alfalfa, Arabidopsis thaliana and tobacco were transformed with a modified bacterial atzA gene, p -atzA, under the control of the cassava vein mosaic virus promoter. All transgenic plant species actively expressed p -atzA and grew over a wide range of atrazine concentrations. Thin layer chromatography analyses indicated that in planta expression of p -atzA resulted in the production of hydroxyatrazine. Hydroponically grown transgenic tobacco and alfalfa dechlorinated atrazine to hydroxyatrazine in leaves, stems and roots. Moreover, p -atzA was found to be useful as a conditional-positive selection system to isolate alfalfa and Arabidopsis transformants following Agrobacterium -mediated transformation. Our work suggests that the in planta expression of p -atzA may be useful for the development of plants for the phytoremediation of atrazine-contaminated soils and soil water, and as a marker gene to select for the integration of exogenous DNA into the plant genome. [source] Determination of atrazine, deethylatrazine and simazine in water at parts-per-trillion levels using solid-phase extraction and gas chromatography/ion trap mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2003W. T. Ma Methods for trace analysis of atrazine and simazine in water have been developed by using stable-isotope dilution with detection by gas chromatography/mass spectrometry. D5 -Atrazine was used as the internal standard for the determination of atrazine and deethylatrazine, while 13C3 -simazine was used for simazine analysis. Water samples were fortified with known amounts of the internal standards and submitted to solid-phase extraction with a C18 bonded-silica cartridge. A gas chromatograph coupled with an ion-trap mass spectrometer was used to analyze the water sample extracts. Method detection limits were 38 parts-per-trillion (ppt) for atrazine and deethylatrazine and 75 ppt for simazine. The accuracy of the method, represented by relative analytical errors, was less than 15%, and the method precision was less than 5% (relative standard deviation, n,=,9). The method was successfully applied to analyze surface water samples collected from a reservoir and a river at ppt levels. Copyright © 2003 John Wiley & Sons, Ltd. [source] Zebrafish as a model for developmental neurotoxicity testing,,BIRTH DEFECTS RESEARCH, Issue 7 2006Christopher Ton Abstract BACKGROUND: To establish zebrafish as a developmental toxicity model, we used 7 well-characterized compounds to examine several parameters of neurotoxicity during development. METHODS: Embryos were exposed by semistatic immersion from 6 hrs postfertilization (hpf). Teratogenicity was assessed using a modified method previously developed by Phylonix. Dying cells in the brain were assessed by acridine orange staining (these cells are likely to be apoptotic). Motor neurons were assessed by antiacetylated tubulin staining and catecholaminergic neurons were visualized by antityrosine hydroxylase staining. RESULTS: Atrazine, dichlorodiphenyltrichloroethane (DDT), and 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) were primarily teratogenic and not specifically neurotoxic. 2,4-dichlorophenoxyacetic acid (2,4-D), dieldrin, and nonylphenol showed specific neurotoxicity; dieldrin and nonylphenol were specifically toxic to catecholaminergic neurons. Malathion, although not teratogenic, showed some nonspecific toxicity. CONCLUSIONS: Teratogenicity measured in 96-hpf zebrafish is predictive of mammalian teratogenicity and is useful in determining whether a compound causes specific neurotoxicity or general developmental toxicity. Induction of apoptosis or necrosis is an indicator of neurotoxicity. An effect on motor neurons in the caudal third of the embryo correlates with expected defects in motility. Overall, our results showed a strong correlation with mammalian data and suggest that zebrafish is a predictive animal model for neurotoxicity screening. Birth Defects Research (Part A) 76:553,567, 2006. Published 2006 Wiley-Liss, Inc. [source] Utilization of a Copper Solid Amalgam Electrode for the Analytical Determination of AtrazineELECTROANALYSIS, Issue 22 2005Djenaine De, Souza Abstract A copper solid amalgam electrode was prepared and used for the voltammetric determination of atrazine in natural water samples by square wave voltammetry. This electrode is a convenient substitute for the hanging mercury electrode since it is selective, sensitive, reliable and inexpensive and presents low toxicity characteristic. The detection limit of atrazine obtained in pure water (laboratory samples) was shown to be lower than the maximum limit of residue established for natural water by the Brazilian Environmental Agency. The relative standard deviation for 10 different measurements was found to be only 3.98% in solutions containing 8.16×10,6,mol L,1 of atrazine. In polluted stream water samples, the recovery measurements were approximately 70.00%, sustaining the applicability of the proposed methodology to the analysis of atrazine in such matrices. [source] Fitness drift of an atrazine-degrading population under atrazine selection pressureENVIRONMENTAL MICROBIOLOGY, Issue 3 2008Marion Devers Summary Pseudomonas sp. ADP harbouring the atrazine catabolic plasmid ADP1 was subcultured in liquid medium containing atrazine as sole source of nitrogen. After approximately 320 generations, a new population evolved which replaced the initial population. This newly evolved population grew faster and degraded atrazine more rapidly than the initial population. Plasmid profiles and Southern blot analyses revealed that the evolved strain, unlike the ancestral strain, presented a tandem duplication of the atzB gene encoding the second enzyme of the atrazine catabolic pathway responsible for the transformation of hydroxyatrazine to N-isopropylammelide. This duplication resulted from a homologous recombination that occurred between two direct repeats of 6.2 kb flanking the atzB gene and constituted by the insertion sequences IS1071, ISPps1 and a pdhL homologous sequence. This study highlights the IS-mediated plasticity of atrazine-degrading potential and demonstrates that insertion sequences not only help to disperse the atrazine-degrading gene but also improve the fitness of the atrazine-degrading population. [source] Evaluated fate and effects of atrazine and lambda-cyhalothrin in vegetated and unvegetated microcosms,,ENVIRONMENTAL TOXICOLOGY, Issue 5 2005J. L. Bouldin Abstract Contaminants such as nutrients, metals, and pesticides can interact with constructed wetlands and existing drainage ditches used as agricultural best-management practices. Our research has shown that the presence of macrophytes and a hydrologic regime aid in the transfer and transformation of pesticides associated with agricultural runoff. This study consisted of application of both atrazine (triazine herbicide) and lambda-cyhalothrin (pyrethroid insecticide) to vegetated and unvegetated microcosms in order to measure the fate and effects of pesticides applied at suggested field application rates. Exposures focused on monocultures of Ludwigia peploides (water primrose) and Juncus effusus (soft rush). Pesticide sorption was evident through concentrations of atrazine and lambda-cyhalothrin in plant tissue as high as 2461.4 and 86.50 ,g/kg, respectively. Toxicity was measured in water from unvegetated microcosms for 28 days and in Chironomus tentans (midge larvae) exposed to sediment collected from 3 h to 56 days in microcosms receiving the pesticide combination. The comparative survival of test organisms in this study suggests that effective mitigation of pesticides from runoff can depend on the macrophyte contact and vegetative attributes associated with ditches. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 487,498, 2005. [source] Effects of the organophosphorus insecticide fenitrothion on growth in five freshwater species of phytoplanktonENVIRONMENTAL TOXICOLOGY, Issue 4 2001Consuelo Sabater Abstract The acute toxicity of the insecticide fenitrothion was measured using four freshwater algae (Chlorella saccharophila, Chlorella vulgaris, Scenedesmus acutus, and Scenedesmus subspicatus) and one cyanobacteria (Pseudanabaena galeata). Insecticide concentrations eliciting 50% growth reduction over 96 hr (EC50) ranged from 0.84 to 11.9 mg/L. Fenitrothion was more toxic than other pesticides studied with the same algal species such as chlorsulfuron, molinate, and pyridaphenthion. The transformation of effective concentrations of fenitrothion and other pesticides obtained from toxicity measurements into percent of the saturation level in water is used as a first evaluation of potential hazard to aquatic systems. The insecticides fenitrothion and pyridaphenthion were less hazardous than the herbicides atrazine, benthiocarb, cinosulfuron, chlorsulfuron, methyl-bensulfuron, and molinate. The two species of Chlorella and the cyanobacterium Pseudanabaena were more tolerant to fenitrothion than the two species of Scenedesmus. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 314,320, 2001 [source] Reproductive health of bass in the Potomac, USA, drainage: Part 1.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2009Exploring the effects of proximity to wastewater treatment plant discharge Abstract Intersex (specifically, testicular oocytes) has been observed in male smallmouth bass (SMB; Micropterus dolomieu) and other centrarchids in the South Branch of the Potomac River, USA, and forks of the Shenandoah River, USA, during the past five years. This condition often is associated with exposure to estrogenic endocrine-disrupting chemicals in some fish species, but such chemicals and their sources have yet to be identified in the Potomac. In an attempt to better understand the plausible causes of this condition, we investigated the reproductive health of bass sampled up- and downstream of wastewater treatment plant (WWTP) effluent point sources on the Potomac River in Maryland, USA. Smallmouth bass were sampled from the Conococheague Creek and the Monocacy River, and largemouth bass (LMB; Micropterus salmoides) were collected near the Blue Plains WWTP on the mainstem of the Potomac River. Chemical analyses of compounds captured in passive samplers at these locations also were conducted. A high prevalence of intersex (82,100%) was identified in male SMB at all sites regardless of collection area. A lower prevalence of intersex (23%) was identified in male LMB collected at the Blue Plains site. When up- and downstream fish were compared, significant differences were noted only in fish from the Conococheague. Differences included condition factor, gonadosomatic index, plasma vitellogenin concentration, and estrogen to testosterone ratio. In general, chemicals associated with waste-water effluent, storm-water runoff, and agriculture were more prevalent at the downstream sampling sites. An exception was atrazine and its associated metabolites, which were present in greater concentrations at the upstream sites. It appears that proximity to effluent from WWTPs may influence the reproductive health of bass in the Potomac watershed, but inputs from other sources likely contribute to the widespread, high incidence of testicular oocytes. [source] Reproductive health of bass in the Potomac, USA, drainage: Part 2.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2009Seasonal occurrence of persistent, emerging organic contaminants Abstract The seasonal occurrence of organic contaminants, many of which are potential endocrine disruptors, entering the Potomac River, USA, watershed was investigated using a two-pronged approach during the fall of 2005 and spring of 2006. Passive samplers (semipermeable membrane device and polar organic chemical integrative sampler [POCIS]) were deployed in tandem at sites above and below wastewater treatment plant discharges within the watershed. Analysis of the samplers resulted in detection of 84 of 138 targeted chemicals. The agricultural pesticides atrazine and metolachlor had the greatest seasonal changes in water concentrations, with a 3.1- to 91-fold increase in the spring compared with the level in the previous fall. Coinciding with the elevated concentrations of atrazine in the spring were increasing concentrations of the atrazine degradation products desethylatrazine and desisopropylatrazine in the fall following spring and summer application of the parent compound. Other targeted chemicals (organochlorine pesticides, polycyclic aromatic hydrocarbons, and organic wastewater chemicals) did not indicate seasonal changes in occurrence or concentration; however, the overall concentrations and number of chemicals present were greater at the sites downstream of wastewater treatment plant discharges. Several fragrances and flame retardants were identified in these downstream sites, which are characteristic of wastewater effluent and human activities. The bioluminescent yeast estrogen screen in vitro assay of the POCIS extracts indicated the presence of chemicals that were capable of producing an estrogenic response at all sampling sites. [source] Development of negligible depletion hollow fiber,protected liquid-phase microextraction for sensing freely dissolved triazinesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2009Xialin Hu Abstract A new sampling method, termed negligible depletion hollow fiber,protected liquid-phase microextraction, was developed for sensing the freely dissolved concentration (Cfree) and evaluating the availability of atrazine (ATR), desethyl atrazine (DEA), and simazine (SIM) in water. The sampling device was prepared by impregnating 1-octanol to both the pores and the lumen of a piece of polypropylene microporous hollow fiber membrane. After equilibrium and negligible depletion extraction, the 1-octanol in the lumen of the hollow fiber (10 ,l) was collected for determination of triazines. Determination of Cfree and the distribution coefficient to 1-octanol (DOW) can be performed with this technique. A wide linear working range (1,200 ,g/L) and low detection limits (0.1,1 ,g/L) were obtained for triazines. Measured log DOW values of DEA (1.44 ± 0.04), SIM (2.06 ± 0.06), and ATR (2.33 ± 0.05) agreed well with those reported in the literature. The measured DOW values were independent of the chemical concentration and sample pH (pH 3,10) and negligibly affected by the sample salinity (0,500 mM), suggesting that environmentally relevant pH and salinity have no significant effects on the availability of triazines. Although a slight (,31%) increase of Cfree was observed, one-way analysis of variance indicated the Cfree of triazines were not significantly affected by the presence of Aldrich humic acid, Acros humic acid, and bovine albumin V (dissolved organic carbon [DOC], 0,100 mg/L). From 3 to 36% of the spiked triazines, however, were found to associate with the dissolved organic matter (DOM) in surface-water samples (DOC, 32.0,61.9 mg/L), suggesting the origin of the DOM is a key parameter in determining its association with and, thus, the availability of triazines. [source] Adsorption of hydrophobic organic compounds onto a hydrophobic carbonaceous geosorbent in the presence of surfactants,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Peng Wang Abstract The adsorption of hydrophobic organic compounds (HOCs; atrazine and diuron) onto lampblack was studied in the presence of nonionic, cationic, and anionic surfactants (Triton® X-100), benzalkonium chloride [BC], and linear alkylbenzene sulfonate [LAS]) to determine the effect of the surfactant on HOC adsorption onto a hydrophobic carbonaceous geosorbent. Linear alkylbenzene sulfonate showed an adsorption capacity higher than that of BC but similar to that of Triton X-100, implying the charge property of a surfactant is not a useful indicator for predicting the surfactant's adsorption onto a hydrophobic medium. The results also indicated that the octanol-water partition coefficient (Kow) of a surfactant is not a good predictor of that surfactant's sorption onto a hydrophobic medium. Under subsaturation adsorption conditions (i.e., before sorption saturation is reached), surfactant adsorption reduced HOC adsorption to a significant extent, with the reduction in HOC adsorption increasing monotonically with the amount of surfactant adsorbed. Among the three surfactants, Triton X-100 was the most effective in reducing HOC adsorption, whereas BC and LAS showed similar effectiveness in this regard. Under the same amount of the surfactant sorbed, the reduction in atrazine adsorption was consistently greater than that for diuron because of atrazine's lower hydrophobicity. No significant difference was observed in the amount of the HOC adsorbed under different adsorption sequences. Our results showed that the presence of surfactant can significantly decrease HOC adsorption onto hydrophobic environmental media and, thus, is important in predicting HOC fate and transport in the environment. [source] Agricultural pesticides and selected degradation products in five tidal regions and the main stem of Chesapeake Bay, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2007Laura L. McConnell Abstract Nutrients, sediment, and toxics from water sources and the surrounding airshed are major problems contributing to poor water quality in many regions of the Chesapeake Bay, an important estuary located in the mid-Atlantic region of the United States. During the early spring of 2000, surface water samples were collected for pesticide analysis from 18 stations spanning the Chesapeake Bay. In a separate effort from July to September of 2004, 61 stations within several tidal regions were characterized with respect to 21 pesticides and 11 of their degradation products. Three regions were located on the agricultural Delmarva Peninsula: The Chester, Nanticoke, and Pocomoke Rivers. Two regions were located on the more urban western shore: The Rhode and South Rivers and the Lower Mobjack Bay, including the Back and Poquoson Rivers. In both studies, herbicides and their degradation products were the most frequently detected chemicals. In 2000, atrazine and metolachlor were found at all 18 stations. In 2004, the highest parent herbicide concentrations were found in the upstream region of Chester River. The highest concentration for any analyte in these studies was for the ethane sulfonic acid of metolachlor (MESA) at 2,900 ng/L in the Nanticoke River. The degradation product MESA also had the greatest concentration of any analyte in the Pocomoke River (2,100 ng/L) and in the Chester River (1,200 ng/L). In the agricultural tributaries, herbicide degradation product concentrations were more strongly correlated with salinity than the parent herbicides. In the two nonagricultural watersheds on the western shore, no gradient in herbicide concentrations was observed, indicating the pesticide source to these areas was water from the Bay main stem. [source] Seasonality effects on pharmaceuticals and s -triazine herbicides in wastewater effluent and surface water from the Canadian side of the upper Detroit RiverENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2006Wen Yi Hua Abstract The influence of seasonal changes in water conditions and parameters on several major pharmacologically active compounds (PhACs) and s -triazine herbicides was assessed in the wastewater and sewage treatment plant (WSTP) effluent as well as the downstream surface water from sites on the Canadian side of the upper Detroit River, between the Little River WSTP and near the water intake of a major drinking water treatment facility for the City of Windsor (ON, Canada). The assessed PhACs were of neutral (carbamazepine, cotinine, caffeine, cyclophosphamide, fluoxetine, norfluoxetine, pentoxifylline, and trimethoprim) and acidic (ibuprofen, bezafibrate, clofibric acid, diclofenac, fenoprofen, gemfibrozil, indomethacin, naproxen, and ketoprofen) varieties. The major assessed s -triazine herbicides were atrazine, simazine, propazine, prometon, ametryn, prometryn, and terbutryn. At sampling times from September 2002 to June 2003, 15 PhACs were detected in the WSTP effluent at concentrations ranging from 1.7 to 1,244 ng/L. The PhAC concentrations decreased by as much 92 to 100% at the Little River/Detroit River confluence because of the river dilution effect, with further continual decreases at sites downstream from the WSTP. The only quantifiable s -triazine in WSTP effluent, atrazine, ranged from 6.7 to 200 ng/L and was higher in Detroit River surface waters than in WSTP effluent. Only carbamazepine, cotinine, and atrazine were detectable at the low-nanogram and subnanogram levels in surface waters near a drinking water intake site. Unlike the PhACs, atrazine in the Detroit River is not attributable to point sources, and it is heavily influenced by seasonal agricultural usage and runoff. Detroit River surface water concentrations of carbamazepine, cotinine, and atrazine may present a health concern to aquatic wildlife and to humans via the consumption of drinking water. [source] Atrazine increases the sodium absorption in frog (Rana esculenta) skinENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2006Giuseppe Cassano Abstract The presence of atrazine in agricultural sites has been linked to the decline in amphibian populations. The efforts of the scientific community generally are directed toward investigating the long-term effect of atrazine on complex functions (reproduction or respiration), but in the present study, we investigated the short-term effect on the short-circuit current (ISC), a quantitative measure of the ion transport operated by frog (Rana esculenta) skin. Treatment with 5 ,M atrazine (1.08 mg/L) does not affect the transepithelial outfluxes of [14C]mannitol or [14C]urea; therefore, atrazine does not damage the barrier properties of frog skin. Atrazine causes a dose-dependent increase in the short-circuit current, with a minimum of 4.64 ± 0.76 ,A/cm2 (11.05% ± 1.22%) and a maximum of 12.7 ± 0.7 ,A/cm2 (35% ± 2.4%) measured at 10 nM and 5 ,M, respectively. An increase in ISC also is caused by 5 ,M ametryne, prometryn, simazine, terbuthylazine, or terbutryn (other atrazine derivatives). In particular, atrazine increases the transepithelial 22Na+ influx without affecting the outflux. Finally, stimulation of ISC by atrazine is suppressed by SQ 22536, H89, U73122, 2-aminoethoxydiphenyl borate, and W7 (blockers of adenylate cyclase, protein kinase A, phospholipase C, intracellular Ca2+ increase, and calmodulin, respectively), whereas indomethacin and calphostin C (inhibitors of cyclooxygenase and protein kinase C, respectively) have no effect. [source] Effects of atrazine and iridovirus infection on survival and life-history traits of the long-toed salamander (Ambystoma macrodactylum)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006Diane Forson Abstract Environmental contaminants and emerging infectious diseases are implicated as factors contributing to global amphibian declines. However, few studies have tested the interaction of these factors. We exposed six-week-old, larval long-toed salamanders (Ambystoma macrodactylum) to Ambystoma tigrinum virus (ATV; 0 or 103.5 plaque-forming units/ml) and sublethal concentrations of atrazine (0, 1.84, 18.4, and 184 ,g/L) in a 4 × 2 factorial design for 30 d. We tested the effects of atrazine and virus on mass and snout-vent length (SVL) at metamorphosis and larval period as well as on rates of mortality and viral infectivity. We confirmed ATV transmission to A. macrodactylum via polymerase chain reaction, but infection rates were lower than expected, consistent with the theory predicting lower pathogen transmission to nonnative hosts. Larvae exposed to both atrazine and ATV had lower levels of mortality and ATV infectivity compared to larvae exposed to virus alone, suggesting atrazine may compromise virus efficacy. The highest atrazine level (184 ,g/L) accelerated metamorphosis and reduced mass and SVL at metamorphosis significantly relative to controls. Exposure to ATV also significantly reduced SVL at metamorphosis. The present study suggests moderate concentrations of atrazine may ameliorate effects of ATV on long-toed salamanders, whereas higher concentrations initiate metamorphosis at a smaller size, with potential negative consequences to fitness. [source] Aquatic herbicide exposure increases salamander desiccation risk eight months later in a terrestrial environmentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2005Jason R. Rohr Abstract Contaminants and climate change may be factors in amphibian declines. However, few studies have explored their joint impacts on postmetamorphic amphibians, a life stage of great importance to amphibian population dynamics. Here, we examine the effects of premetamorphic exposure (mean exposure of 64 d) to ecologically relevant concentrations of the globally common herbicide atrazine (0, 4, 40, 400 ,g/L) on the behavior and water retention of lone and grouped postmetamorphic, streamside salamanders, Ambystoma barbouri. Salamanders exposed to ,40 ,g/L of atrazine exhibited greater activity, fewer water-conserving behaviors, and accelerated water loss four and eight months after exposure compared to controls. No recovery from atrazine exposure was detected and its effects were independent of the presence of conspecifics. These results are consistent with the hypothesis that adverse climatic conditions and contaminants can interact to harm post-metamorphic amphibians; however, they suggest that these two stressors need not be experienced simultaneously to do so. These results emphasize the importance of considering both latent and cumulative effects of temporally linked stressors in ecotoxicology. [source] Empirical and modeling evidence of regional atmospheric transport of current-use pesticidesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2004Derek C. G. Muir Abstract Water samples from 30 lakes in Canada and the northeastern United States were analyzed for the occurrence of 27 current-use pesticides (CUPs). Eleven CUPs were frequently detected in lakes receiving agricultural inputs as well as in remote lakes hundreds of kilometers from known application areas. These included the triazine herbicide atrazine and its desethylated degradation product; the herbicides alachlor, metolachlor, and dacthal; the organophosphate insecticides chlorpyrifos, diazinon, and disulfoton; the organochlorine insecticides ,-endosulfan and lindane; and the fungicides chlorothalonil and flutriafol. For six of the pesticides, empirical half-distances on the order of 560 to 1,820 km were estimated from the water-concentration gradient with latitude. For most of the pesticides, a suite of assessment models failed to predict such atmospheric long-range transport behavior, unless the effect of periods of lower hydroxyl radical concentrations and dry weather were taken into account. Observations and model results suggest that under the conditions prevailing in south-central Canada (relatively high latitude, low precipitation rates), many CUPs will be able to undergo regional-scale atmospheric transport and reach lakes outside areas of agricultural application. When assessing the potential of fairly reactive and water-soluble substances to undergo long-range transport, it is imperative to account for periods of no precipitation, to assure that degradation rate constants are correct, and to apply oxidant concentrations that are valid for the region and time period of interest. [source] Plasma sex steroid concentrations and gonadal aromatase activities in African clawed frogs (Xenopus laevis) from South AfricaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2004Markus Hecker Abstract Adult African clawed frogs (Xenopus laevis) were collected from a corn-growing region (CGR) and a non-corn-growing region (NCGR) with different exposure profiles for atrazine and related triazines. Physical, chemical, and biological parameters from the catchment areas were also measured. Frogs were surveyed for possible effects of exposure to triazine herbicides on plasma testosterone (T) and estradiol (E2) titers, gonadal aromatase activity, and gonad growth (GSI). Concentrations of both T and E2 varied among locations and were correlated to some accessory factors, such as pH, several ions, and metals. Greatest median plasma T concentrations (males: 19 ng/ml; females: 16 ng/ml) occurred in frogs inhabiting NCGR as compared to those from the CGR (males: 4 ng/ml; females: 1 ng/ml). Median E2 concentrations were also greater in frogs collected from the NCGR (males: 3 ng/ml; females: 28 ng/ml) than those in frogs from the CGR (males: 2 ng/ml; females: 5 ng/ml). Because some exposure to agricultural chemicals at both regions occurred, as did simultaneous exposures to multiple chemicals, a regression analysis was employed. Negative correlations were observed between plasma T concentrations and concentrations of atrazine, deisopropylatrazine, deethylatrazine, and tertbuthylazine in females and between T and diaminochlorotriazine in males. Estradiol in females exhibited a significant negative correlation with atrazine and deethylatrazine. No correlations were observed between gonadal aromatase activity or GSI and any of the agricultural chemicals measured. Median aromatase activities in ovaries varied among sampling sites ranging from 7 to >3,000 times greater than those in males when measurable. Testicular aromatase activity was below the detection limit of the assay in male frogs at most of the sites. Although exposure to agricultural inputs did not affect aromatase activities, effects of atrazine or coapplied pesticides on sex steroid homeostasis cannot be excluded at this point. [source] Effects of sublethal concentrations of atrazine and nitrate on metamorphosis of the African clawed frogENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2003Karen Brown Sullivan Abstract Tadpoles of the African clawed frog (Xenopus laevis) were exposed to sublethal concentrations of atrazine (0, 40, and 320 ,g/L) and nitrate (0, 37, and 292 mg/L) from feeding stage to metamorphosis. A 3 × 3 factorial design was used to identify both single and interactive effects. At metamorphosis, tadpole weight, snout,vent length (SVL), and hematocrit were determined. Mean mortality was greater in tanks receiving 320 ,g/L atrazine; nitrate had no effect on mortality. Significant differences for all mean traits at metamorphosis occurred among atrazine treatments; higher atrazine exposure increased time to metamorphosis and decreased weight, SVL, and hematocrit. Nitrate treatments were not significantly different. Significant interaction tests between atrazine and nitrate occurred for weight and SVL at metamorphosis; the specific type of interaction varied among treatments. Assuming an additive mixture model, at low atrazine (40 ,g/L), the addition of 37 mg/L nitrate produced SVL values less than expected (a synergistic effect) while the addition of 292 mg/L nitrate yielded SVL values greater than expected (an antagonistic effect). A similar response was noted for tadpoles in the 320-,g/L atrazine treatments. These results indicate that environmentally realistic concentrations of atrazine exert a negative impact on amphibian metamorphosis. Also, this study suggests that mixtures of agricultural chemicals, even if sublethal, may exert negative and not necessarily consistent mixture effects. [source] Increased toxicity to invertebrates associated with a mixture of atrazine and organophosphate insecticidesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Troy D. Anderson Abstract This study examined the joint toxicity of atrazine and three organophosphate (OP) insecticides (chlorpyrifos, methyl parathion, and diazinon) exposed to Hyalella azteca and Musca domestica. A factorial design was used to evaluate the toxicity of binary mixtures in which the lethal concentration/lethal dose (LC1/LD1, LC5/LD5, LC15/LD15, and LC50/LD50) of each OP was combined with atrazine concentrations of 0, 10, 40, 80, and 200 ,g/L for H. azteca and 0, 200, and 2,000 ng/mg for M. domestica. Atrazine concentrations (>40 ,g/L) in combination with each OP caused a significant increase in toxicity to H. azteca compared with the OPs dosed individually. Acetylcholinesterase (AChE) activity also was examined for the individual OPs with and without atrazine treatment. Atrazine in combination with each of the OPs resulted in a significant decrease in AChE activity compared with the OPs dosed individually. In addition, H. azteca that were pretreated with atrazine (>40 ,g/L) were much more sensitive to the OP insecticides compared with H. azteca that were not pretreated with atrazine before being tested. Topical exposure to atrazine concentrations did not significantly increase OP toxicity to M. domestica. The results of this study indicate the potential for increased toxicity in organisms exposed to environmental mixtures. [source] Effects of water hardness and dissolved organic material on bioavailability of selected organic chemicalsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2001Jarkko Akkanen Abstract The influence of water hardness and dissolved organic matter (DOM) on bioavailability of organic chemicals to Daphnia magna was studied by using benzo[a]pyrene (BaP), pyrene, atrazine, and 3,3,,4,4,-tetrachlorobiphenyl (TCB) as model compounds. Two types of DOM were used, namely Lake Kontiolampi, Joeusuu, Finland water (KL) and Nordic reference fulvic acid (NoFA) dissolved in artificial freshwater. Binding of the four contaminants by KL, DOM decreased with increasing water hardness. Furthermore, increasing hardness reduced the binding of BaP and pyrene to NoFA. The binding of atrazine and TCB by NoFA was low and was not significantly affected by water hardness. In the DOM-free samples, the bioconcentration of the four contaminants in D. magna usually was not affected by water hardness. In the presence of DOM, the bioconcentration factors (BCFs) were lower (except for atrazine) than in the DOM-free controls. In the presence of both types of DOM, increasing water hardness resulted in higher BCFs for BaP. The bioconcentration of pyrene and TCB increased with increasing water hardness in the presence of KL DOM. In conclusion, the effects of DOM and water hardness on bioavailability of hydrophobic chemicals depend on the type of chemical and on the properties of DOM. [source] Genetic indicators of herbicide stress in the pacific oyster Crassostrea gigas under experimental conditionsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2000Dario Moraga Abstract This study examined use of the oyster Crassostrea gigas as a bioindicator of experimental pollution caused by two concentrations of five pesticides (atrazine, isoproturon, alachlore, metolachlore, and diuron) used in agricultural and urban activities. The effect of these pesticides on the genetic structure of the marine bivalve was studied as part of an environmental biomonitoring project. This research was performed on two natural estuarine populations sampled along the French Atlantic coast as part of an ongoing monitoring program to survey the ecosystem of Brittany using two approaches: identifying the genetic markers based on the alleles and genotypes associated with pollution effects, and searching for a correlation between these markers and the sensitivity or tolerance of individuals under stress conditions. Results indicate a differential survival of individuals subjected to the various pollutants examined. The sensitivity of alleles and genotypes to environmental stress can be assessed based on the significant differences in allele and genotype frequencies observed between resistant and sensitive individuals when subjected to the pesticides. This genetic study included examination of five enzyme systems (Ak, Pgi, Cap, Pgm, and Mdh) involved in physiologic processes. A total of six alleles and five genotypes at three loci (Ak, Pgi, and Pgm) were identified as being markers of resistance or sensitivity. It is hypothesized that these markers could be used as potential genetic markers in estuarine ecosystem monitoring. [source] Effect of earthworm activity (Aporrectodea giardi) on atrazine adsorption and biodegradationEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2006T. Alekseeva Summary We investigated the influence of earthworm (Aporrectodea giardi) activity on soil properties and on atrazine (AT) adsorption and biodegradation by comparing a coarse-textured smectite-free wetland soil (Brittany, France) with the earthworm casts derived from the top horizon of this soil. Casts are characterized by lower pH, are enriched in organic carbon (OC) and clay content, have a larger cation exchange capacity, and a greater exchangeable Ca content. The clay mineralogy of the soil studied and casts is characterized by a muscovite,kaolinite,chlorite association. In addition, the clay fraction of the soil contains lepidocrocite (,-FeOOH), which was not found in the casts. Atrazine adsorption isotherms were reasonably well described by the Freundlich equation and were all non-linear. The mean amounts of adsorbed AT for starting concentrations of 3,30 mg litre,1 ranged from 8 to 34%, being largest in earthworm casts. Soil AT adsorption capacity was well correlated with OC content. Non-decomposed organic matter present in the coarse size fractions and specific compounds present in earthworm casts (proteins, mono- and polysaccharides, polyphenols, sugars, lignin) and microbial and fungal biomass contribute to AT adsorption. Weak electrostatic (physical) sorption of AT on organic compounds and on mineral surfaces prevails. For casts, the formation of additional hydrophobic interactions between AT and SOM is proposed. We also studied AT biodegradation by the model bacterium Pseudomonas sp. strain ADP in the presence of soils or earthworm casts. An enhancement of the AT disappearance rate was observed in the presence of all the solid matrices tested compared with that obtained in an aqueous medium. The biodegradation rate was shown to be dependent not only on the OC content of the solid matrix, but mainly on its composition and structure. [source] Molecular identification and expression study of differentially regulated genes in the Pacific oyster Crassostrea gigas in response to pesticide exposureFEBS JOURNAL, Issue 2 2005Arnaud Tanguy The effects of pesticide contamination on the metabolism of marine molluscs are poorly documented. We investigated the response of a marine bivalve, the Pacific oyster, Crassostrea gigas, using a suppression subtractive hybridization method to identify up- and down-regulated genes after a 30-day exposure period to herbicides (a cocktail of atrazine, diuron and isoproturon, and to the single herbicide glyphosate). A total of 137 unique differentially expressed gene sequences was identified, as well as their associated physiological process. The expression of 18 of these genes was analyzed by RT-PCR under laboratory experimental conditions. The metabolic functions they are associated with include xenobiotic detoxification, energy production, immune system response and transcription. This study provides a preliminary basis for studying the response of marine bivalves to long-term herbicide exposure in terms of regulated gene expression and characterizes new potential genetic markers of herbicide contamination. [source] Effects of possible endocrine disruptors on MyD88-independent TLR4 signalingFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2008Takahiro Ohnishi Abstract Endocrine disrupting chemicals (EDCs) may potentially worsen infectious diseases because EDCs disturb human immune function by interfering with endocrine balance. To evaluate the influence of EDCs on the innate immune function of macrophages, we investigated the effects of 37 possible EDCs on lipopolysaccharide-induced activation of the IFN-, promoter. Alachlor, atrazine, benomyl, bisphenol A, carbaryl, diethyl phthalate, dipropyl phthalate, kelthane, kepone, malathion, methoxychlor, octachlorostyrene, pentachlorophenol, nonyl phenol, p -octylphenol, simazine and ziram all inhibited the activation. Kepone and ziram showed strong inhibitory effects. Aldicarb, amitrole, benzophenone, butyl benzyl phthalate, 2,4-dichlorophenoxy acetic acid, dibutyl phthalate, 2,4-dichlorophenol, dicyclohexyl phthalate, diethylhexyl adipate, diethylhexyl phthalate, dihexyl phthalate, di- n -pentyl phthalate, methomyl, metribuzin, nitrofen, 4-nitrotoluene, permethrin, trifluralin, 2,4,5-trichlorophenoxyacetic acid and vinclozolin had no significant effects at 100 ,M. These results indicate that some agrochemicals and resin-related chemicals may potentially inhibit macrophage function, which suggests that endocrine disruptors may influence the development of infectious diseases. [source] | |||||||||||||||||||