Refine search
Results 931-940 of 4,043
Effects of dietary lead exposure on vitamin levels in great tit nestlings – An experimental manipulation Full text
2016
Ruiz, Sandra | Espín, Silvia | Rainio, Miia | Ruuskanen, Suvi | Salminen, Juha-Pekka | Lilley, Thomas M. | Eeva, Tapio
Exposure to metal pollution negatively affects animal physiology, including nutrient metabolism, but in the wild an effect can seldom be attributed to a single metal. Moreover, little is known about how the metabolism of vitamins, essential micronutrients for developing juveniles, is affected by toxic metals. Therefore we experimentally investigated the effects of lead (Pb), a widespread toxic metal, on four fat-soluble vitamins A (total and retinol), D3, E (total and α-tocopherol) and K and carotenoids (lutein, zeaxanthin and unidentified) in great tit (Parus major) nestlings. In addition to a control group where no Pb was provided, two Pb-dosed groups were compared to a metal exposed group in the vicinity of a Ni–Cu smelter. We examined whether Pb treatment affects vitamin homeostasis and how the response of Pb-treated birds relates to that of a population under industrial exposure of Pb and other metals. For this purpose, vitamin and carotenoid levels were quantified with UPLC-MS from plasma of 7 days-old nestlings. All metal exposed groups showed increased vitamin A and retinol levels. However, vitamin levels were not directly associated with fecal Pb levels, with the exception of retinol, which was positively correlated with fecal Pb. Alpha-tocopherol, lutein and zeaxanthin levels were positively associated with body mass and wing growth rate. To conclude, Pb exposure increased plasma vitamin A and retinol levels while the levels of other vitamins and carotenoids rather reflected secondary pollution effects via differences in habitat and diet quality at the smelter site. Our findings suggest Pb exposed nestlings may allocate the vitamins needed for growth and development to fight the physiological stress thus compromising their fitness.
Show more [+] Less [-]Benchmark study on fine-mode aerosol in a big urban area and relevant doses deposited in the human respiratory tract Full text
2016
Avino, Pasquale | Protano, Carmela | Vitali, Matteo | Manigrasso, Maurizio
It is well-known that the health effects of PM increase as particle size decreases: particularly, great concern has risen on the role of UltraFine Particles (UFPs). Starting from the knowledge that the main fraction of atmospheric aerosol in Rome is characterized by significant levels of PM2.5 (almost 75% of PM10 fraction is PM2.5), the paper is focused on submicron particles in such great urban area. The daytime/nighttime, work-/weekdays and cold/hot seasonal trends of submicron particles will be investigated and discussed along with NOx and total PAH drifts demonstrating the primary origin of UFPs from combustion processes. Furthermore, moving from these data, the total dose of submicron particles deposited in the respiratory system (i.e., head, tracheobronchial and alveolar regions in different lung lobes) has been estimated. Dosimeter estimates were performed with the Multiple-Path Particle Dosimetry model (MPPD v.2.1). The paper discusses the aerosol doses deposited in the respiratory system of individuals exposed in proximity of traffic. During traffic peak hours, about 6.6 × 1010 particles are deposited into the respiratory system. Such dose is almost entirely made of UFPs. According to the greater dose estimated, right lung lobes are expected to be more susceptible to respiratory pathologies than left lobes.
Show more [+] Less [-]Assessment of microbial communities in PM1 and PM10 of Urumqi during winter Full text
2016
Gou, Huange | Lu, Jianjiang | Li, Shanman | Tong, Yanbin | Xie, Chunbin | Zheng, Xiaowu
Recently, inhalable particulate matter has been reported to carry microorganisms responsible for human allergy and respiratory disease. The unique geographical environment and adverse weather conditions of Urumqi cause double pollution of dust and smog, but research on the microbial content of the atmosphere has not been commenced. In this study, 16S and 18S rRNA gene sequencing were conducted to investigate the microbial composition of Urumqi's PM1 and PM10 pollutants in winter. Results showed that the bacterial community is mainly composed of Proteobacteria, Firmicutes and Actinobacteria, Proteobacteria accounted for the most proportion which was significant difference in some aforementioned studies. Ascomycota and Basidiomycota constitute the main part of the fungal microbial community. The difference of bacterial relative abundance in sample point is greater than in particle sizes. The sequences of several pathogenic bacteria and opportunistic pathogens were also detected, such as Acinetobacter, Delftia, Serratia, Chryseobacterium, which may impact on immunocompromised populations (elderly, children and postoperative convalescence patients), and some fungal genera may cause several plant diseases. Our findings may serve an important reference value in the global air microbial propagation and air microbial research in desert.
Show more [+] Less [-]On the association between outdoor PM2.5 concentration and the seasonality of tuberculosis for Beijing and Hong Kong Full text
2016
You, Siming | Tong, Yen Wah | Neoh, Koon Gee | Dai, Yanjun | Wang, Chi-Hwa
Tuberculosis (TB) is still a serious public health problem in various countries. One of the long-elusive but critical questions about TB is what the risk factors are and how they contribute for its seasonality. An ecologic study was conducted to examine the association between the variation of outdoor PM2.5 concentration and the TB seasonality based on the monthly TB notification and PM2.5 concentration data of Hong Kong and Beijing. Both descriptive analysis and Poisson regression analysis suggested that the outdoor PM2.5 concentration could be a potential risk factor for the seasonality of TB disease. The significant relationship between the number of TB cases and PM2.5 concentration was not changed when regression models were adjusted by sunshine duration, a potential confounder. The regression analysis showed that a 10 μg/m3 increase in PM2.5 concentrations during winter is significantly associated with a 3% (i.e. 18 and 14 cases for Beijing and Hong Kong, respectively) increase in the number of TB cases notified during the coming spring or summer for both Beijing and Hong Kong. Three potential mechanisms were proposed to explain the significant relationship: (1) increased PM2.5 exposure increases host's susceptibility to TB disease by impairing or modifying the immunology of the human respiratory system; (2) increased indoor activities during high outdoor PM2.5 episodes leads to an increase in human contact and thus the risk of TB transmission; (3) the seasonal change of PM2.5 concentration is correlated with the variation of other potential risk factors of TB seasonality. Preliminary evidence from the analysis of this work favors the first mechanism about the PM2.5 exposure-induced immunity impairment. This work adds new horizons to the explanation of the TB seasonality and improves our understanding of the potential mechanisms affecting TB incidence, which benefits the prevention and control of TB disease.
Show more [+] Less [-]Homeostatic regulation of copper in a marine fish simulated by a physiologically based pharmacokinetic model Full text
2016
Wang, Xun | Wang, Wen-Xiong
Copper (Cu) is an essential yet potentially toxic metal, thus delicate homeostatic controls are developed in the fish. In this study, a physiologically based pharmacokinetic (PBPK) model was developed to simulate the homeostatic regulation of Cu in a marine fish (Terapon jarbua) under dietary and waterborne exposures. In this model, fish were schematized as a six-compartment model, with the intestine being divided into two sub-compartments (chyme and gut wall). The blood was assumed to be the “carrier” distributing Cu into different compartments. The transfer rates between different compartments were determined in fish during Cu exposure (20 d) and depuration (20 d). The differences in Cu transfer from chyme to gut wall between dietary and waterborne treatments suggested that the intestine regulated the dietary uptake and re-absorption of Cu from the chyme. The extremely low uptake rate constant (0.0013 d−1) for gills under waterborne exposure indicated that gills strongly restricted Cu uptake from the ambient water. For both treatments, the liver had considerable input rate through the enterohepatic circulation and comparably high exchange rate with the blood, suggesting that the liver can efficiently accumulate newly absorbed Cu. The differences in Cu output from the liver between dietary and waterborne treatments suggested that it can effectively regulate the redistribution of Cu. All of these observations demonstrated that the liver played the central role in Cu homeostasis by serving as the main depository and distributing center. Modeling results also indicated that renal and branchial excretion was of minor importance, whereas biliary excretion combined with defecation played the most important role in whole-body Cu elimination in marine fish. The effective regulation by the “Blood-Liver-Intestine” cycle could be the main reason for the relatively low levels of Cu in fish.
Show more [+] Less [-]Trophic transfer of nano-TiO2 in a paddy microcosm: A comparison of single-dose versus sequential multi-dose exposures Full text
2016
Kim, Jung In | Park, Hyung-Geun | Chang, Kwang-Hyeon | Nam, D.H. | Yeo, Min-Kyeong
In the present study, replicated paddy microcosm systems were used to investigate the environmental fate and trophic transfer of titanium nanoparticles (NPs) over a period of 14 days. Most TiO2 NPs immediately settled down in the sediment, and high accumulations of nano TiO2 in the sandy loam sediment and biofilm were observed. The test organisms (quillworts, water dropworts, duckweeds, biofilms, river snails, and Chinese muddy loaches) and environmental media (freshwater, sandy loam sediment) were exposed to sequential low doses (2 mg/L at 1 h, 4 days, and 9 days) or a single high-dose (6 mg/L) of TiO2 NPs. The bioconcentration factors (BCFs) of nano-TiO2 in biofilms, quillworts, duckweeds, and Chinese muddy loaches were higher in the sequential multi-dose group than in the single-dose group. Chinese muddy loaches showed higher bioaccumulation factors (BAFs) over their prey than river snails. The difference in the carbon isotope ratios between Chinese muddy loaches and river snails was less than 2‰, and an approximately 4‰ difference in the stable nitrogen isotope ratio was observed in the two aquatic predators from their major prey (e.g., biofilms or particulate organic matter). The trophic levels between biofilms and river snails and between biofilms and Chinese muddy loaches were 2.8 and 2.4 levels, respectively. These results indicate that these two predators consumed biofilm and other alternative preys at a higher level than biofilm. Although the trophic transfer rates of TiO2 are generally low, relatively higher biomagnification factors (BMFs) were found in Chinese muddy loaches (0.04–0.05) than in river snails (0.01–0.02). These results suggest that TiO2 NPs show greater movement in the sediment than in the water and that TiO2 NPs can be retained through aquatic food chains more after a sequential low-dose exposure than after a single high-dose exposure.
Show more [+] Less [-]Blood trihalomethane levels and the risk of total cancer mortality in US adults Full text
2016
Min, Chin-yŏng | Min, Kyoung-Bok
Although animal data have suggested the carcinogenic activity of trihalomethanes (THMs), there is inconsistent evidence supporting the link between THM exposure and cancers in humans.We investigated the association between specific and total blood THM levels with the risk of total cancer mortality in adults.We analyzed data from the 1999–2004 Third National Health and Nutrition Examination Survey and the Linked Mortality File of the United States. A total of 933 adults (20–59 years of age) with available blood THM levels and no missing data for other variables were included. Four different THM species (chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform) were included, and the codes associated with cancer (malignant neoplasm) were C00 through C97, based on the underlying causes of death listed in the International Classification of Disease 10the Revision.Compared with adults in the lowest DBCM, bromoform, and total brominated THM tertiles, those in the highest DBCM, bromoform, and total brominated THM tertiles exhibited adjusted hazard ratios (HR) of total cancer mortality of 4.97 (95% confidence interval (CI) = 1.59–15.50), 4.94 (95% CI = 1.56–15.61), and 3.42 (95% CI = 1.21–15.43) respectively. The risk of total cancer mortality was not associated with increases in blood chloroform and total THM levels.We found that the baseline blood THM species, particularly brominated THMs, were significantly associated with total cancer mortality in adults. Although this study should be confirm by other studies, our findings suggest a possible link between THM exposures and cancer.
Show more [+] Less [-]Quantification of vehicle fleet PM10 particulate matter emission factors from exhaust and non-exhaust sources using tunnel measurement techniques Full text
2016
Lawrence, Samantha | Sokhi, Ranjeet | Ravindra, Khaiwal
Road tunnels act like large laboratories; they provide an excellent environment to quantify atmospheric particles emission factors from exhaust and non-exhaust sources due to their known boundary conditions. Current work compares the High Volume, Dichotomous Stacked Filter Unit and Partisol Air Sampler for coarse, PM10 and PM2.5 particle concentration measurement and found that they do not differ significantly (p = 95%). PM2.5 fraction contributes 66% of PM10 proportions and significantly influenced by traffic (turbulence) and meteorological conditions. Mass emission factors for PM10 varies from 21.3 ± 1.9 to 28.8 ± 3.4 mg/vkm and composed of Motorcycle (0.0003–0.001 mg/vkm), Cars (26.1–33.4 mg/vkm), LDVs (2.4–3.0 mg/vkm), HDVs (2.2–2.8 mg/vkm) and Buses (0.1 mg/vkm). Based on Lawrence et al. (2013), source apportionment modelling, the PM10 emission of brake wear (3.8–4.4 mg/vkm), petrol exhaust (3.9–4.5 mg/vkm), diesel exhaust (7.2–8.3 mg/vkm), re-suspension (9–10.4 mg/vkm), road surface wear (3.9–4.5 mg/vkm), and unexplained (7.2 mg/vkm) were also calculated. The current study determined that the combined non-exhaust fleet PM10 emission factor (16.7–19.3 mg/vkm) are higher than the combined exhaust emission factor (11.1–12.8 mg/vkm). Thus, highlight the significance of non-exhaust emissions and the need for legislation and abatement strategies to reduce their contributions to ambient PM concentrations.
Show more [+] Less [-]Hotspots of black carbon and PM2.5 in an urban area and relationships to traffic characteristics Full text
2016
Targino, Admir Créso | Gibson, Mark David | Krecl, Patricia | Rodrigues, Marcos Vinicius Costa | dos Santos, Maurício Moreira | de Paula Corrêa, Marcelo
Three instrumented bicycles were used to measure black carbon (BC) and PM2.5 concentrations in a midsized city in southern Brazil. The objective of this study was to map the spatial distribution of BC and PM2.5, to identify air pollution hotspots and to assess factors that may affect the concentrations of these pollutants, e.g. traffic volume, number of heavy-duty diesel vehicles (HDDV), position of traffic signals and street incline. The cyclists collected data in the city centre along streets of different traffic density during nine sampling sessions in the weekday morning and afternoon rush hours, between March 13 and April 28, 2015. The sampling by bicycle covered an area of 2.70 km2, over variable elevation, and travelled a total distance of 215 km. BC and PM2.5 exhibited a large spatial variability on a scale of tens of metres and the concentrations were positively correlated with traffic counts, but exhibited a stronger relationship with the number of HDDV. These results imply that older buses and diesel-powered trucks may be the main driver behind the high pollution levels in the city's inner core. We observed a strong relationship between BC concentrations at junctions managed by traffic signals and the quantity of HDDV. The mean BC concentration was found to be 8.10 μg m−3 near traffic signals located on an inclined street (HDDV > 100 vehicles h−1) compared to traffic signals on flat terrain (6.00 μg m−3), which can be attributed to the higher acceleration required at the start of motion. This pattern was less evident for PM2.5 concentrations.
Show more [+] Less [-]Geographic information systems and multivariate analysis to evaluate fecal bacterial pollution in coastal waters of Andaman, India Full text
2016
Dheenan, Palaiyaa Sukumaran | Jha, Dilip Kumar | Das, Apurba Kumar | Vinithkumar, Nambali Valsalan | Devi, Marimuthu Prashanthi | Kirubagaran, Ramalingam
Urbanization of coastal areas in recent years has driven us to consider a new approach for visually delineating sites that are contaminated with fecal bacteria (FB) in the coastal waters of the Andaman Islands in India. Geo-spatial analysis demarcated harbor, settlement, and freshwater/discharge influenced zones as hot spots for FB, while the open sea was demarcated as a cold spot. The land use types, such as developed and agriculture, with more anthropogenic activities increasing the FB counts while open sea showed the least FB. Box whisker plot indicated an increasing FB trend in the coastal waters during monsoon. Furthermore, principal component analysis revealed 67.35%, 78.62% and 70.43% of total variance at Port Blair, Rangat and Aerial bays, respectively. Strong factor loading was observed for depth (0.95), transparency (0.93), dissolved oxygen (0.93) and fecal streptococci (0.85). Distance proximity analysis revealed that fecal contaminations diluted significantly (P < 0.05) at the distance of 2.1 km toward the deeper or open sea water. This study demonstrates the effectiveness of an integrated approach in identifying the sources of fecal contamination and thus helping in better monitoring and management of coastal waters.
Show more [+] Less [-]