خيارات البحث
النتائج 141 - 150 من 4,302
Diet and habitat use influence Hg and Cd transfer to fish and consequent biomagnification in a highly contaminated area: Augusta Bay (Mediterranean Sea)
2017
Signa, Geraldina | Mazzola, Antonio | Tramati, Cecilia Doriana | Vizzini, Salvatrice
Total mercury (T-Hg) and cadmium (Cd) were measured in twenty species of fish to study their bioaccumulation patterns and trophodynamics in the Augusta Bay food web. Adult and juvenile fish were caught in 2012 in Priolo Bay, south of the Augusta harbour (Central Mediterranean Sea), which is known for the high trace element and polycyclic aromatic hydrocarbon contamination level. T-Hg concentration was found to significantly increase along δ15N and from pelagic to benthic sedentary fish, revealing a marked influence of trophic position and habitat use (sensu Harmelin 1987) on T-Hg accumulation within ichthyofauna. Cd showed the opposite pattern, in line with the higher trace element (TE) excretion rates of high trophic level fish and the lower level of Cd environmental contamination.Trophic pathways were first characterised in the Priolo Bay food web using carbon and nitrogen stable isotopes (δ13C, δ15N) and a single main trophic pathway characterised the Priolo Bay food web. Biomagnification was then assessed, including basal sources (surface sediment, macroalgae), zooplankton, benthic invertebrates and fish. T-Hg and Cd were found to biomagnify and biodilute respectively based on the significant linear regressions between log[T-Hg] and log[Cd] vs. δ15N of sources and consumers and the trophic magnification factors (TMFs) of 1.22 and 0.83 respectively. Interestingly, different Cd behaviour was found considering only the benthic pathway which leads to the predatory gastropod Hexaplex trunculus. The positive slope and the higher TMF indicated active biomagnification in this benthic food web due to the high bioaccumulation efficiency of this benthic predator. Our findings provide new evidences about the role of Priolo sediments as a sources of pollutants for the food web, representing a threat to fish and, by domino effect, to humans.
اظهر المزيد [+] اقل [-]Oxidative potential of particulate matter 2.5 as predictive indicator of cellular stress
2017
Crobeddu, Bélinda | Aragao-Santiago, Leticia | Bui, Linh-Chi | Boland, Sonja | Baeza Squiban, Armelle
Particulate air pollution being recognized to be responsible for short and long term health effects, regulations for particulate matter with an aerodynamic diameter less than 2.5 (PM2.5) are more and more restrictive. PM2.5 regulation is based on mass without taking into account PM2.5 composition that drives toxicity. Measurement of the oxidative potential (OP) of PM could be an additional PM indicator that would encompass the PM components involved in oxidative stress, the main mechanism of PM toxicity. We compared different methods to evaluate the intrinsic oxidative potential of PM2.5 sampled in Paris and their ability to reflect the oxidative and inflammatory response in bronchial epithelial cells used as relevant target organ cells. The dithiothreitol depletion assay, the antioxidant (ascorbic acid and glutathione) depletion assay (OPAO), the plasmid scission assay and the dichlorofluorescein (DCFH) oxidation assay used to characterize the OP of PM2.5 (10–100 μg/mL) provided positive results of different magnitude with all the PM2.5 samples used with significant correlation with different metals such as Cu and Zn as well as total polyaromatic hydrocarbons and the soluble organic fraction. The OPAO assay showed the best correlation with the production of intracellular reactive oxygen species by NCI-H292 cell line assessed by DCFH oxidation and with the expression of anti-oxidant genes (superoxide dismutase 2, heme-oxygenase-1) as well as the proinflammatory response (Interleukin 6) when exposed from 1 to 10 μg/cm2. The OPAO assay appears as the most prone to predict the biological effect driven by PM2.5 and related to oxidative stress.
اظهر المزيد [+] اقل [-]Phthalate levels and related factors in children aged 6–12 years
2017
Wu, Wei | Zhou, Feng | Wang, Yue | Ning, Yong | Yang, Jian-Ye | Zhou, Yi-Kai
Although previous studies showed that children are widely exposed to phthalates, the sources of phthalate exposure for school-aged children in China are not well understood. This study aimed to assess phthalate metabolite levels and explore the factors influencing exposure in children. We collected demographic data and biological samples from 336 children aged 6–12 years. We calculated urinary concentrations of 14 mono-phthalate metabolites and conducted chi-square (χ2) tests and logistic regression analysis to determine the variables associated with phthalate levels. Mono-n-butyl phthalate (MnBP) and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) were the most abundant urinary phthalate metabolites. In addition, housing type, decorating materials in the home, and frequency of canned food consumption were associated with exposure to low molecular weight phthalates. Water source, duration of time spent playing with toys, residential area, and frequency of canned food consumption were associated with exposure to high molecular weight phthalates. Based on these results, potential strategies to reduce exposure to phthalates include avoiding plastic food containers and chemical fragrances as well as eating fewer processed foods, especially canned foods, and foods in plastic packaging.
اظهر المزيد [+] اقل [-]Cadmium in rice: Transport mechanisms, influencing factors, and minimizing measures
2017
Li, Hui | Luo, Na | Li, Yan Wen | Cai, Quan Ying | Li, Hui Yuan | Mo, Ce Hui | Wong, Ming Hung
Cadmium (Cd) accumulation in rice and its subsequent transfer to food chain is a major environmental issue worldwide. Understanding of Cd transport processes and its management aiming to reduce Cd uptake and accumulation in rice may help to improve rice growth and grain quality. Moreover, a thorough understanding of the factors influencing Cd accumulation will be helpful to derive efficient strategies to minimize Cd in rice. In this article, we reviewed Cd transport mechanisms in rice, the factors affecting Cd uptake (including physicochemical characters of soil and ecophysiological features of rice) and discussed efficient measures to immobilize Cd in soil and reduce Cd uptake by rice (including agronomic practices, bioremediation and molecular biology techniques). These findings will contribute to ensuring food safety, and reducing Cd risk on human beings.
اظهر المزيد [+] اقل [-]Comparative proteomic analysis reveals heart toxicity induced by chronic arsenic exposure in rats
2017
Huang, Qingyu | Xi, Guochen | Alamdar, Ambreen | Zhang, Jie | Shen, Heqing
Arsenic is a widespread metalloid in the environment, which poses a broad spectrum of adverse effects on human health. However, a global view of arsenic-induced heart toxicity is still lacking, and the underlying molecular mechanisms remain unclear. By performing a comparative quantitative proteomic analysis, the present study aims to investigate the alterations of proteome profile in rat heart after long-term exposure to arsenic. As a result, we found that the abundance of 81 proteins were significantly altered by arsenic treatment (35 up-regulated and 46 down-regulated). Among these, 33 proteins were specifically associated with cardiovascular system development and function, including heart development, heart morphology, cardiac contraction and dilation, and other cardiovascular functions. It is further proposed that the aberrant regulation of 14 proteins induced by arsenic would disturb cardiac contraction and relaxation, impair heart morphogenesis and development, and induce thrombosis in rats, which is mediated by the Akt/p38 MAPK signaling pathway. Overall, these findings will augment our knowledge of the involved mechanisms and develop useful biomarkers for cardiotoxicity induced by environmental arsenic exposure.
اظهر المزيد [+] اقل [-]Characterisation of volatile organic compounds (VOCs) released by the composting of different waste matrices
2017
Schiavon, Marco | Martini, Luca Matteo | Corrà, Cesare | Scapinello, Marco | Coller, Graziano | Tosi, P. (Paolo) | Ragazzi, Marco
The complaints arising from the problem of odorants released by composting plants may impede the construction of new composting facilities, preclude the proper activity of existing facilities or even lead to their closure, with negative implications for waste management and local economy. Improving the knowledge on VOC emissions from composting processes is of particular importance since different VOCs imply different odour impacts. To this purpose, three different organic matrices were studied in this work: dewatered sewage sludge (M1), digested organic fraction of municipal solid waste (M2) and untreated food waste (M3). The three matrices were aerobically biodegraded in a bench-scale bioreactor simulating composting conditions. A homemade device sampled the process air from each treatment at defined time intervals. The samples were analysed for VOC detection. The information on the concentrations of the detected VOCs was combined with the VOC-specific odour thresholds to estimate the relative weight of each biodegraded matrix in terms of odour impact. When the odour formation was at its maximum, the waste gas from the composting of M3 showed a total odour concentration about 60 and 15,000 times higher than those resulting from the composting of M1 and M2, respectively. Ethyl isovalerate showed the highest contribution to the total odour concentration (>99%). Terpenes (α-pinene, β-pinene, p-cymene and limonene) were abundantly present in M2 and M3, while sulphides (dimethyl sulphide and dimethyl disulphide) were the dominant components of M1.
اظهر المزيد [+] اقل [-]Temperature exposure during pregnancy and birth outcomes: An updated systematic review of epidemiological evidence
2017
Zhang, Yunquan | Yu, Chuanhua | Wang, Lu
Seasonal patterns of birth outcomes have been observed worldwide, and there was increasing evidence that ambient temperature played as a trigger of adverse birth outcomes, such as preterm birth (PTB), low birth weight (LBW), and stillbirth. To systematically review updated epidemiological evidence about the relationship between temperature exposure during pregnancy and PTB, LBW, and stillbirth, we searched for related studies published in English from electronic databases and references of identified papers. We only included original articles that directly reported the effects of prenatal temperature exposure on birth outcomes. The characteristics and main findings of included studies were examined. A total of 36 epidemiological studies were finally included in this review. Most of these studies focused on PTB and LBW, while less attention has been paid to stillbirth that was relatively rare in the occurrence. Several designs including ecological (e.g., descriptive and time-series) and retrospective cohort studies (e.g., case-crossover and time-to-event) were applied to assess temperature effects on birth outcomes. Temperature metrics and exposure windows varied greatly in these investigations. Exposure to high temperature was generally found to be associated with PTB, LBW, and stillbirth, while several studies also reported the adverse impact of low temperature on birth outcomes of PTB and LBW. Despite no conclusive causality demonstrated, the current evidence for adverse effect on birth outcomes was stronger for heat than for cold. In summary, the evidence linking birth outcomes with ambient temperature was still very limited. Consequently, more related studies are needed worldwide and should be conducted in diversified climate zones, so as to further ascertain the association between temperature and birth outcomes. Future studies should focus on more sophisticated study designs, more accurate estimation of temperature exposure during pregnancy, and more efficient methods to find out the exposure windows, as well as cold-related effects on birth outcomes.
اظهر المزيد [+] اقل [-]Relationships between acrylamide and glycidamide hemoglobin adduct levels and allergy-related outcomes in general US population, NHANES 2005–2006
2017
Guo, Jing | Yu, Dongdong | Lv, Na | Bai, Rongpan | Xu, Chunjing | Cao, Weiming | Chen, Guangdi
Acrylamide-induced immunotoxicity and allergic dermatitis have been reported in animal experiments and clinical reports, respectively. However, epidemiological evidence from the general population is limited.The purpose of the present study was to estimate the associations between acrylamide exposure and allergy-related outcomes in the general US population.A total of 6982 subjects were selected from the National Health and Nutrition Examination Survey 2005–2006 (NHANES). Internal exposure was measured by the hemoglobin adducts of acrylamide (HbAA) and its metabolite glycidamide (HbGA). Allergy-related outcomes including asthma, hay fever, allergy, itchy rash, sneeze, wheeze and eczema were obtained by self-administered questionnaires. Allergic sensitization was assessed by the total immunoglobulin E (IgE) levels. The associations of HbAA and HbGA quartiles with allergy-related outcomes were calculated using logistic regression models with multivariable adjustments. Analyses were additionally stratified according to age, gender and serum cotinine levels.When setting quartile 1 of HbAA as reference, the odds ratios (ORs) [95% confidence intervals (CIs)] of quartile 2 to 4 for eczema were 1.18 (0.79–1.76), 1.14 (0.73–1.78) and 1.58 (1.14–2.18), respectively (ptrend = 0.002). Individuals at the highest quartile of HbGA had significantly elevated likelihoods of itchy rash (OR = 1.37, 95% CI = 1.02–1.83, ptrend = 0.032) and eczema (OR = 1.45, 95% CI = 1.06–1.97, ptrend = 0.044). The stratification analyses indicated various results in different subgroups.This study indicated significant associations between HbAA and HbGA levels and the likelihoods of allergy-related outcomes in the general US population, depending on age, gender and smoke exposure status. These findings suggested potential public health concerns for the widespread exposure to acrylamide.
اظهر المزيد [+] اقل [-]A mass balance approach to investigate arsenic cycling in a petroleum plume
2017
Ziegler, Brady A. | Schreiber, Madeline E. | Cozzarelli, Isabelle M. | Crystal Ng, G.-H.
Natural attenuation of organic contaminants in groundwater can give rise to a series of complex biogeochemical reactions that release secondary contaminants to groundwater. In a crude oil contaminated aquifer, biodegradation of petroleum hydrocarbons is coupled with the reduction of ferric iron (Fe(III)) hydroxides in aquifer sediments. As a result, naturally occurring arsenic (As) adsorbed to Fe(III) hydroxides in the aquifer sediment is mobilized from sediment into groundwater. However, Fe(III) in sediment of other zones of the aquifer has the capacity to attenuate dissolved As via resorption. In order to better evaluate how long-term biodegradation coupled with Fe-reduction and As mobilization can redistribute As mass in contaminated aquifer, we quantified mass partitioning of Fe and As in the aquifer based on field observation data. Results show that Fe and As are spatially correlated in both groundwater and aquifer sediments. Mass partitioning calculations demonstrate that 99.9% of Fe and 99.5% of As are associated with aquifer sediment. The sediments act as both sources and sinks for As, depending on the redox conditions in the aquifer. Calculations reveal that at least 78% of the original As in sediment near the oil has been mobilized into groundwater over the 35-year lifespan of the plume. However, the calculations also show that only a small percentage of As (∼0.5%) remains in groundwater, due to resorption onto sediment. At the leading edge of the plume, where groundwater is suboxic, sediments sequester Fe and As, causing As to accumulate to concentrations 5.6 times greater than background concentrations. Current As sinks can serve as future sources of As as the plume evolves over time. The mass balance approach used in this study can be applied to As cycling in other aquifers where groundwater As results from biodegradation of an organic carbon point source coupled with Fe reduction.
اظهر المزيد [+] اقل [-]Assessment of bioavailability of selenium in different plant-soil systems by diffusive gradients in thin-films (DGT)
2017
Peng, Qin | Wang, Mengke | Cui, Zewei | Huang, Jie | Chen, Changer | Guo, Lu | Liang, Dongli
Uptake of selenium (Se) by plants largely depend on the availability of Se in soil. Soils and plants were sampled four times within 8 weeks of plant growth in pot experiments using four plant species. Sequential extraction and diffusive gradients in thin-films (DGT) method were employed to measure Se concentrations in potted soils in selenite- or selenate-amended soils. Results showed that DGT-measured Se concentrations (CDGT−Se) were generally several folds higher for selenate than selenite amended soils, which were obviously affected by the plant species and the duration of their growth. For example, the folds in soil planted with mustard were 1.49–3.47 and those in soils planted with purple cabbage and broccoli, which grew for 3 and 4 weeks after sowing, were 1.06–2.14 and only 0.15–0.62 after 6 weeks of growth. The selenate-amended soil planted with wheat showed an extremely high CDGT−Se compared with selenite-amended soil, except the last harvest. Furthermore, minimal changes in CDGT−Se and soluble Se(IV) were found in selenite-amended soils during plant growth, whereas significant changes were observed in selenate-amended soils (p < 0.05). Additionally, Se distribution in various fractions of soil remarkably changed; the soils planted with purple cabbage and broccoli showed the most obvious change followed by wheat and mustard. Soluble Se(VI) and exchangeable Se(VI) were likely the major sources of CDGT−Se in selenate-amended soils, and soluble Se(IV) was the possible source of CDGT−Se in selenite-amended soils. In selenate-amended soils, soluble Se(VI) and exchangeable Se(VI) were significantly correlated with Se concentrations in purple cabbage, broccoli, and mustard; in wheat, Se concentration was significantly correlated only with soluble Se(VI) but not with exchangeable Se. CDGT−Se eventually became positively correlated with Se concentrations accumulated by different plants, indicating that DGT is a feasible method in predicting plant uptake of selenate but not of selenite.
اظهر المزيد [+] اقل [-]