Home About us Contact
|
Home About us Contact | ||
|
|
||
Agricultural Chemicals (agricultural + chemical)
Selected AbstractsImpacts of nonpoint inputs from potato farming on populations of slimy sculpin (Cottus cognatus)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Michelle A. Gray Abstract The potential influence of agricultural activity, particularly potato cultivation, on slimy sculpin populations (Cottus cognatus) was examined at 19 rivers of New Brunswick, Canada. Comparisons with forested streams resulted in differences in fish density, size, and reproductive performance. Young-of-the-year (YOY) sculpin were present only at two of 11 agricultural sites, though they were present at all nine forested sites. Sediment deposition was greatest at agricultural sites, with increased fine sediments deposited. Larger, coarse sands were deposited at two sites with active forest operations. Temperature had a stronger correlation than sedimentation with sculpin size and density in the agricultural region. Agricultural catchments were warmer than in forested catchments (median = 16.0 and 13.3°C, respectively). Body size of slimy sculpin was correlated positively and YOY densities correlated negatively with temperature, and sites with temperatures ,25°C were devoid of YOY sculpin. Our data indicate there is a significant effect of temperature on slimy sculpin populations in rivers of potato farming areas, highlighting the importance of examining indirect factors when investigating possible impacts of nonpoint source agricultural inputs. Indirect factors such as sediment deposition and temperature need to be considered in order to discriminate accurately the chronic impacts of agricultural chemicals on fish populations. [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] Mobility of major ions and nutrients in the unsaturated zone during paddy cultivation: a field study and solute transport modelling approachHYDROLOGICAL PROCESSES, Issue 20 2007N. Rajmohan Abstract Study of the movement of water and solute within soil profiles is important for a number of reasons. Accumulation of prominent contaminants from agricultural chemicals in the unsaturated zone over the years is a major concern in many parts of the world. As a result, the unsaturated zone has been a subject of great research interest during the past decade. Hence, an intensive field study was conducted in a part of Palar and Cheyyar river basins to understand the variation of major ions and nutrients in the soil zone during paddy cultivation. The chloride and nitrate data were used to model the movement of these chemicals in the unsaturated zone using the HYDRUS-2D model. The field study shows that fertilizer application and irrigation return flow increases the major ions and nutrients concentration in the unsaturated zone. Further, the nutrient concentrations are regulated by plant uptake, fertilizer application and infiltration rate. Additionally, denitrification and soil mineralization processes also regulate the nitrogen concentration in the unsaturated zone. The solute transport modelling study concluded that the simulated results match reasonably with the observed trends. Simulated concentrations of chloride and nitrate for a 5-year period indicate that the concentrations of these ions fluctuate in a cyclic manner (from 60 to 68 mg l,1 and from 3·4 to 3·5 mg l,1 respectively in groundwater) with no upward and downward trend. The influence of excessive fertilizer application on groundwater was also modelled. The model predicts an increase of about 17 mg l,1 of chloride and 2·3 mg l,1 of nitrogen in the groundwater of this area when the application of fertilizers is doubled. The model indicates that the present level of use of agrochemicals is no threat to the groundwater quality. Copyright © 2007 John Wiley & Sons, Ltd. [source] Semen quality in fertile US men in relation to geographical area and pesticide exposureINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 1 2006Shanna H. Swan Summary We conducted the first US study to compare semen quality among study centres using standardized methods and strict quality control. We present data on semen quality in partners of 493 pregnant women recruited through prenatal clinics in four US cities during 1999,2001. Sperm concentration, semen volume and motility were determined at the centres and morphology was assessed at a central laboratory. While between-centre differences in sperm morphology and sample volume were small, sperm concentration and motility were significantly reduced in Columbia, MO (MO) relative to men in New York, NY, Minneapolis, MN and Los Angeles, CA; total number of motile sperm was 113 × 106 in MO and 162, 201 and 196 × 106 in CA, MN and NY respectively. Differences among centres remained significant in multivariate models that controlled for abstinence time, semen analysis time, age, race, smoking, history of sexually transmitted disease and recent fever (all p -values <0.01). We hypothesized that poorer sperm concentration and motility in MO men relative to other centres might be related to agricultural pesticides that are commonly used in the mid-west. We investigated this hypothesis by conducting a nested case,control study within the MO cohort. We selected 25 men in this cohort for whom all semen parameters (concentration, % normal morphology and % motile) were low as cases and an equal number of men for whom all semen parameters were within normal limits as controls. We measured metabolites of eight non-persistent, current-use pesticides in urine samples the men had provided at the time of semen collection. Pesticide metabolite levels were elevated in cases compared with controls for the herbicides alachlor and atrazine, and for the insecticide diazinon (2-isopropoxy-4-methyl-pyrimidinol) (p -values for Wilcoxon rank test = 0.0007, 0.012, and 0.0004 for alachlor, atrazine and diazinon respectively). Men with higher levels of alachlor or diazinon were significantly more likely to be cases than men with low levels [odds ratios (OR) = 30.0, 16.7 for alachlor and diazinon respectively], as were men with atrazine over the limit of detection (OR = 11.3). These associations between current-use pesticides and reduced semen quality suggest that agricultural chemicals may have contributed to the reduced semen quality seen in fertile men from mid-Missouri. [source] ANTIBACTERIAL ACTIVITY AND BINDING ABILITY OF BOVINE LACTOFERRIN AGAINST PSEUDOMONAS SPP.JOURNAL OF FOOD SAFETY, Issue 1 2008WOAN-SUB KIM ABSTRACT The antibacterial activity of bovine lactoferrin was tested against Pseudomonas fluorescens and Pseudomonas syringae. The activity was studied by monitoring the growth of a Pseudomonas spp. in the presence or absence of bovine apo-lactoferrin, bovine holo-lactoferrin or native-lactoferrin in liquid media at different concentrations. Lactoferrin-binding proteins in the membrane fractions of Pseudomonas spp. were detected using far-Western blot analysis. The addition of bovine lactoferrin to the medium inhibited the growth of all tested strains. Furthermore, the growth of P. fluorescens and P. syringae was strongly inhibited by bovine apo-lactoferrin. The estimated molecular weights of lactoferrin-binding proteins in P. fluorescens were 70, 49, 47 and 25 kDa, and 70, 48 and 28 kDa in P. syringae. PRACTICAL APPLICATIONS Pseudomonas fluorescens is an important psychrotrophic bacterium responsible for undesirable flavors in milk and dairy products. Thus, flavor and texture defects, such as bitterness and running paste, were also reported. In addition, Pseudomonas syringae causes various diseases on many different susceptible plant species, generally producing chlorotic and necrotic lesions on leaves and fruits. The resultant bacterial spoilage causes considerable economic losses for the food and dairy industries. At present, antiseptics and agricultural chemicals are used for defense of foods and vegetables from these bacteria, but such substances are known to deleteriously affect the human body. The results of this study demonstrate that bovine lactoferrin significantly inhibits the growth of P. fluorescens and P. syringae. The results indicate that the incorporation of bovine lactoferrin is expected to protect dairy products, food and fruits from pathogenic bacteria. [source] Assessment of occupational health and safety risks of farmworkers in Colorado ,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue S2 2002Martha Soledad Vela-Acosta MD Abstract Background Migrant farmworkers face a variety of hazards including exposure to pesticides and agricultural chemicals. However, few studies have quantatively evaluated these risks. Methods Hazards were assessed during 32 field surveys conducted in the agricultural fields and 15 surveys at five camps. Observations of 1,461 farmworkers for potential hazards were recorded. Estimated risk was evaluated on a four-point scale (no hazard, minor, serious, and critical). A total of 229 farmworkers were interviewed about field conditions. Results Two out of the five camps did not have safe drinking water. Risks for farmworkers were lower when a manager was living on site. Field surveys estimated higher risk when provision of sanitation was deficient (P,<,0.05). Farmworkers' responses concerning field conditions differed from the survey findings. Conclusions Risks for farmworkers depended largely on the environment provided. Discordances between survey results and farmworkers' interview responses suggested that self-reported data might have limited validity for this population. Working and living conditions require improvement to decrease occupational risks for farmworkers. Am. J. Ind. Med. Suppl. 2:19,27, 2002. © 2002 Wiley-Liss, Inc. [source] | ||||||||||