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1.
Associations of Short-Term and Long-Term Exposure to Ambient Air Pollutants With Hypertension: A Systematic Review and Meta-Analysis.
Cai, Y, Zhang, B, Ke, W, Feng, B, Lin, H, Xiao, J, Zeng, W, Li, X, Tao, J, Yang, Z, et al
Hypertension (Dallas, Tex. : 1979). 2016;(1):62-70
Abstract
Hypertension is a major disease of burden worldwide. Previous studies have indicated that air pollution might be a risk factor for hypertension, but the results were controversial. To fill this gap, we performed a meta-analysis of epidemiological studies to investigate the associations of short-term and long-term exposure to ambient air pollutants with hypertension. We searched all of the studies published before September 1, 2015, on the associations of ozone (O3), carbon monoxide (CO), nitrogen oxide (NO2 and NOX), sulfur dioxide (SO2), and particulate matter (PM10 and PM2.5) with hypertension in the English electronic databases. A pooled odds ratio (OR) for hypertension in association with each 10 μg/m(3) increase in air pollutant was calculated by a random-effects model (for studies with significant heterogeneity) or a fixed-effect model (for studies without significant heterogeneity). A total of 17 studies examining the effects of short-term (n=6) and long-term exposure (n=11) to air pollutants were identified. Short-term exposure to SO2 (OR=1.046, 95% confidence interval [CI]: 1.012-1.081), PM2.5 (OR=1.069, 95% CI: 1.003-1.141), and PM10 (OR=1.024, 95% CI: 1.016-1.032) were significantly associated with hypertension. Long-term exposure (a 10 μg/m(3) increase) to NO2 (OR=1.034, 95% CI: 1.005-1.063) and PM10 (OR=1.054, 95% CI: 1.036-1.072) had significant associations with hypertension. Exposure to other ambient air pollutants (short-term exposure to NO2, O3, and CO and long-term exposure to NOx, PM2.5, and SO2) also had positive relationships with hypertension, but lacked statistical significance. Our results suggest that short-term or long-term exposure to some air pollutants may increase the risk of hypertension.
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2.
Geographical variation in the response to nitrogen deposition in Arabidopsis lyrata petraea.
Vergeer, P, Van Den Berg, LLJ, Bulling, MT, Ashmore, MR, Kunin, WE
The New phytologist. 2008;(1):129-141
Abstract
The adaptive responses to atmospheric nitrogen deposition for different European accessions of Arabidopsis lyrata petraea were analysed using populations along a strong atmospheric N-deposition gradient. Plants were exposed to three N-deposition rates, reflecting the rates at the different locations, in a full factorial design. Differences between accessions in the response to N were found for important phenological and physiological response variables. For example, plants from low-deposition areas had higher nitrogen-use efficiencies (NUE) and C : N ratios than plants from areas high in N deposition when grown at low N-deposition rates. The NUE decreased in all accessions at higher experimental deposition rates. However, plants from high-deposition areas showed a limited capacity to increase their NUE at lower experimental deposition rates. Plants from low-deposition areas had faster growth rates, higher leaf turnover rates and shorter times to flowering, and showed a greater increase in growth rate in response to N deposition than those from high-deposition areas. Indications for adaptation to N deposition were found, and results suggest that adaptation of plants from areas high in N deposition to increased N deposition has resulted in the loss of plasticity.
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3.
[Air pollution and cardiovascular and cerebrovascular disease: Epidemiologic data].
Zeller, M, Giroud, M, Royer, C, Benatru, I, Besancenot, JP, Rochette, L, Cottin, Y
Presse medicale (Paris, France : 1983). 2006;(10 Pt 2):1517-22
Abstract
Recent convergent data suggest that air pollution affects the risk of acute atherothrombotic events including both myocardial infarction and ischemic stroke. The principal epidemiologic studies begun in the 1990s first examined the respiratory effects of atmospheric pollution and then focused on how pollution peaks affected cardiovascular risk. These studies used data from large metropolitan areas in North America and Asia as well as several large European cities to demonstrate the clear existence of a relation between air pollution and cardio- and cerebrovascular mortality. They also observed an increase in hospital admissions for myocardial infarctions and cerebrovascular accidents on days with high air pollution levels. The pollutants involved have not yet been clearly designated, but it appears that fine suspended particulate matter (PM2.5) and gaseous pollutants such as ozone appear to contribute strongly to these harmful effects. A complete analysis of these data shows the need for a thorough evaluation of the cardio- and cerebrovascular risks associated with air pollution, especially in French metropolitan areas. Precise identification of those at high risk from specific pollutants is essential to improve targeting of prevention strategies.
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4.
Tree age dependence and within-canopy variation of leaf gas exchange and antioxidative defence in Fagus sylvatica under experimental free-air ozone exposure.
Herbinger, K, Then, Ch, Löw, M, Haberer, K, Alexous, M, Koch, N, Remele, K, Heerdt, C, Grill, D, Rennenberg, H, et al
Environmental pollution (Barking, Essex : 1987). 2005;(3):476-82
Abstract
We characterized leaf gas exchange and antioxidative defence of two-year-old seedlings and 60-year-old trees of Fagus sylvatica exposed to ambient (1 x O3) or two-fold ambient (2 x O3) O3 concentrations (maximum of 150 ppb) in a free-air canopy exposure system throughout the growing season. Decline in photosynthesis from sun-exposed to shaded conditions was more pronounced in adult than juvenile trees. Seedling leaves and leaves in the sun-exposed canopy had higher stomatal conductance and higher internal CO2 concentrations relative to leaves of adult trees and leaves in shaded conditions. There was a weak overall depression of photosynthesis in the 2 x O3 variants across age classes and canopy positions. Pigment and tocopherol concentrations of leaves were significantly affected by canopy position and tree age, whereas differences between 1 x O3 and 2 x O3 regimes were not observed. Glutathione concentrations were significantly increased under 2 x O3 across both age classes and canopy levels. Seedlings differed from adult trees in relevant physiological and biochemical traits in ozone response. The water-soluble antioxidative systems responded most sensitively to 2 x O3 without regard of tree age or canopy position.
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5.
Comparison of ozone uptake and sensitivity between a phytotron study with young beech and a field experiment with adult beech (Fagus sylvatica).
Nunn, AJ, Kozovits, AR, Reiter, IM, Heerdt, C, Leuchner, M, Lütz, C, Liu, X, Lo W, M, Winkler, JB, Grams, TE, et al
Environmental pollution (Barking, Essex : 1987). 2005;(3):494-506
Abstract
Chamber experiments on juvenile trees have resulted in severe injury and accelerated loss of leaves along with reduced biomass production under chronically enhanced O3 levels. In contrast, the few studies conducted on adult forest trees in the field have reported low O3 sensitivity. In the present study, young beech in phytotrons was more sensitive to O3 than adult beech in the field, although employed O3 regimes were similar. The hypotheses tested were that: (1) differences in O3 uptake were caused by the ontogenetically higher stomatal conductance of young compared to adult trees, (2) the experimental settings in the phytotrons enhanced O3 uptake compared to field conditions, and (3) a low detoxification capacity contributes to the higher O3 sensitivity of the young trees. The higher O3 sensitivity of juvenile beech in the phytotrons is demonstrated to relate to both the experimental conditions and the physiological responsiveness inherent to tree age.
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6.
Dermal, oral, and inhalation pharmacokinetics of methyl tertiary butyl ether (MTBE) in human volunteers.
Prah, J, Ashley, D, Blount, B, Case, M, Leavens, T, Pleil, J, Cardinali, F
Toxicological sciences : an official journal of the Society of Toxicology. 2004;(2):195-205
Abstract
Methyl tertiary butyl ether (MTBE), a gasoline additive used to increase octane and reduce carbon monoxide emissions and ozone precursors, has contaminated drinking water and can lead to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhalation kinetics, 14 volunteers were exposed to 51.3 microg/ml MTBE dermally in tap water for 1 h, drank 2.8 mg MTBE in 250 ml Gatorade(R), and inhaled 3.1 ppm. MTBE for 1 h. Blood and exhaled breath samples were then obtained. Blood MTBE peaked between 15 and 30 min following oral exposure, at the end of inhalation exposure, and ~5 min after dermal exposure. Elimination by each route was described well by a three-compartment model (Rsq >0.9). The Akaike Information Criterion for the three-compartment model was smaller than the two-compartment model, supporting it over the two-compartment model. One metabolite, tertiary butyl alcohol (TBA), measured in blood slowly increased and plateaued, but it did not return to the pre-exposure baseline at the 24-h follow-up. TBA is very water-soluble and has a blood:air partition ratio of 462, reducing elimination by exhalation. Oral exposure resulted in a significantly greater MTBE metabolism into TBA than by other routes based on a greater blood TBA:MTBE AUC ratio, implying significant first-pass metabolism. The slower TBA elimination may make it a better biomarker of MTBE exposure, though one must consider the exposure route when estimating MTBE exposure from TBA because of first-pass metabolism. Most subjects had a baseline blood TBA of 1-3 ppb. Because TBA is found in consumer products and can be used as a fuel additive, it is not a definitive marker of MTBE exposure. These data provide the risk assessment process of pharmacokinetic information relevant to the media through which most exposures occur-air and drinking water.
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7.
Haloalkane hydrolysis by Rhodococcus erythropolis cells: comparison of conventional aqueous phase dehalogenation and nonconventional gas phase dehalogenation.
Erable, B, Goubet, I, Lamare, S, Legoy, MD, Maugard, T
Biotechnology and bioengineering. 2004;(1):47-54
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Abstract
Biofiltration of air polluted by volatile organic compounds is now recognized by the industrial and research communities as an effective and viable alternative to standard environmental technologies. Whereas many studies have focused on solid/liquid/gas biofilters, there have been fewer reports on waste air treatment using other biological processes, especially in a solid/gas biofilter. In this study, a comparison was made of the hydrolysis of halogenated compounds (such as 1-chlorobutane) by lyophilized Rhodococcus erythropolis cells in a novel solid/gas biofilter and in the aqueous phase. We first determined the culture conditions for the production of R. erythropolis cells with a strong dehalogenase activity. Four different media were studied and the amount of 1-chlorobutane was optimized. Next, we report the possibility to use R. erythropolis cells in a solid/gas biofilter in order to transform halogenated compounds in corresponding alcohols. The effect of experimental parameters (total flow into the biofilter, thermodynamic activity of the substrates, temperature, carbon chain length of halogenated substrates) on the activity and stability of lyophilized cells in the gas phase was determined. A critical water thermodynamic activity (a(w)) of 0.4 is necessary for the enzyme to become active and optimal dehalogenase activity for the lyophilized cells is obtained for an a(w) of 0.9. A temperature of reaction of 40 degrees C represents the best compromise between stability and activity. Activation energy of the reaction was determined and found equal to 59.5 KJ/mol. The pH effect on the dehalogenase activity of R. erythropolis cells was also studied in the gas phase and in the aqueous phase. It was observed that pH 9.0 provided the best activity in both systems. We observed that in the aqueous phase R. erythropolis cells were less sensitive to the variation in pH than R. erythropolis cells in the gas phase. Finally, the addition of volatile Lewis base (triethylamine) in the gaseous phase and the action of the lysozyme in order to permeabilize the cells was found to be highly beneficial to the effectiveness of the biofilter.
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8.
Antioxidant supplementation and lung functions among children with asthma exposed to high levels of air pollutants.
Romieu, I, Sienra-Monge, JJ, Ramírez-Aguilar, M, Téllez-Rojo, MM, Moreno-Macías, H, Reyes-Ruiz, NI, del Río-Navarro, BE, Ruiz-Navarro, MX, Hatch, G, Slade, R, et al
American journal of respiratory and critical care medicine. 2002;(5):703-9
Abstract
To evaluate whether acute effects of ozone, nitrogen dioxide, and particulates with mass median diameter less than 10 micro m could be attenuated by antioxidant vitamin supplementation, we conducted a randomized trial using a double-blinded design. Children with asthma (n = 158) who were residents of Mexico City were randomly given a daily supplement of vitamins (50 mg/day of vitamin E and 250 mg/day of vitamin C) or a placebo and were followed from October 1998 to April 2000. Pulmonary function tests were carried out twice a week in the morning. During the follow-up observation period, the mean 1-hour maximum ozone level was 102 ppb (SD = 47), and the mean 24-hour average PM(10) level was 56.7 micro g/m(3) (SD = 27.4). In children with moderate and severe asthma, ozone levels 1 day before spirometry were inversely associated significantly with forced expiratory flow (FEF(25-75)) (-13.32 ml/second/10 ppb; p = 0.000), FEV(1) (-4.59 ml/10 ppb; p = 0.036), and peak expiratory flow (PEF) (-15.01 ml/second/10 ppb; p = 0.04) in the placebo group after adjusting for potential confounding factors. No association between ozone and lung functions was observed in the supplement group. We observed significant differences in lung function decrements between groups for FEF(25-75) and PEF. Our results suggest that supplementation with antioxidants might modulate the impact of ozone exposure on the small airways of children with moderate to severe asthma.
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Human experimental studies on the effects of inhaled particles.
Låstbom, BL, Camner, P
Scandinavian journal of work, environment & health. 2000;:43-8