21 |
Design and setup of exposure system for culture studiesKarlsson, Max, Sahlin, Mikael January 2013 (has links)
In this repost the design of an exposure system for culture studies is presented. The apparatus can expose culture plates to a magnetic field and microwave radiation. The magnetic field is created using a pair of Helmholtz colis which can generate a field with frequencies between 0 and 100 [Hz] and with field strengths between 0 and 8 [Gauss]. Microwaves with frequencies between 1.7 and 1.9 [GHz] at power levels between 0 and 8 [W] are directed at the culture plate using a R-band rectangular waveguide. The setup includes an IR- camera used to observe the temperature distribution of the exposed medium.Trial exposures of Osteoblasts does not show any statistically viable results.
|
22 |
Mobile phone radiation does not induce pro-apoptosis effects in human spermatozoaFalzone, N, Huyser, C, Franken, DR, Leszczynski, D 11 May 2010 (has links)
Recent reports suggest that mobile phone radiation may
diminish male fertility. However, the effects of this radiation on
human spermatozoa are largely unknown. The present study
examined effects of the radiation on induction of apoptosisrelated
properties in human spermatozoa. Ejaculated, densitypurified,
highly motile human spermatozoa were exposed to
mobile phone radiation at specific absorption rates (SARs) of
2.0 and 5.7 W/kg. At various times after exposure, flow
cytometry was used to examine caspase 3 activity, externalization
of phosphatidylserine (PS), induction of DNA strand
breaks, and generation of reactive oxygen species. Mobile
phone radiation had no statistically significant effect on any of
the parameters studied. This suggests that the impairment of
fertility reported in some studies was not caused by the induction
of apoptosis in spermatozoa.
|
23 |
An Assessment of the Contribution of Micro-scale Activities to Personal Pollution Exposure in Commuting Micro-environmentsShrestha, Kreepa January 2009 (has links)
Exposure to traffic pollution has become an increasing concern to public health. A number of studies have demonstrated that the air people breathe in while in transportation
is particularly unsafe due to the high concentrations of carbon monoxide (CO), suspended particles (PM10, PM2.5 and PM1) and ultrafine particles (UFPs). Some studies have suggested that peak exposures of approximately one hour- a typical time spent in a transport micro-environment- may have more damaging health effects than the 24- hour
sampling times current standards apply to Despite the widespread interest in health effects from exposure to traffic pollutants, there is a distinct lack of research of this kind in New Zealand. The research presented in this thesis was designed to assess the effect of
traffic emissions on personal exposure. More specifically, this project intended to examine how exposures differed on different modes of transport and also to investigate
the extent to which transport micro-environments such as car parks, bus stops and metro stations contributed to personal exposure levels. This study is the first of its type in New Zealand, which simultaneously monitored CO, PM and UFP concentrations in the transport micro-environment. Vehicular traffic emissions were shown to be a significant
source of air pollution in populated urban areas, especially in the transport microenvironment. This results of this study showed that the mode of transport is a significant
determinant of personal exposure to pollutants. The information gathered indicated slightly different results for Christchurch and Auckland, possibly due to variations in background levels, traffic counts and meteorological conditions at the time of monitoring. Results from the research also showed that built transport microenvironments
could experience extremely high levels of pollutant exposures. Although
commuters spend a relatively short time in such environments, such short-term peak exposures could contribute significantly to adverse health effects. The results presented here have relevance for both public health and for policies aimed at reducing human
exposures to traffic-related air pollution. It is imperative to incorporate policies which ensure that such built environments are as safe as possible in terms of keeping exposure
levels at a minimum.
|
24 |
Cyclist exposure to traffic pollution: microscale variance, the impact of route choice and comparisons to other modal choices in two New Zealand citiesPattinson, Woodrow January 2009 (has links)
This study aimed to investigate various aspects of cyclist exposure to common urban air pollutants, including CO, PM10, PM2.5, PM1.0 and UFPs. The initial part of the study compared cyclist exposure to that of other transport modes, while the second part addressed the implications of route choice. The final part analysed the effect of proximity to traffic.
Data was collected in Christchurch and Auckland cities over a nine week period, with a total of 53 inter-modal and 7 separate cyclist sampling runs completed. Mobile sampling was conducted using a collection of instruments in four portable kits. Fixed-site
meteorological data was used to find associations between pollutants and temperature and wind speed. Spatial patterns were also considered by means of time-series comparative graphs and colour-coded pollutant concentration GPS mapping. The cyclist mode was up to 61% less exposed than the car for primary pollutants (CO and UFPs), but up to 26% more exposed for PM1.0-10. The bus was generally the most exposed for all pollutants apart from CO. The effect of route choice was substantial, with the off-road cyclist route recording a reduction of 31% for CO and PM1.0, and 53% for UFPs while PM10 was 6%. At a distance of 7 m from traffic, exposure dropped by 30% (UFPs), 22% (CO) and 14% (PM2.5). At 19 m, concentrations decreased a further 17%, 13% and 8%, respectively. When moving much further away from traffic (~700 m), the effect was far less pronounced and no difference was observed for CO past 19 m.
Conclusions suggest that for most pollutants studied, the cyclist mode faces much lower exposure than other modes, especially when traveling through backstreets and cycle tracks. Significant exposure reductions can also be made when only a very small distance away from traffic emissions. This has positive implications for health, sustainable city planning and active-mode transport promotion.
|
25 |
Transparent neural network modellingRoadknight, C. M. January 2000 (has links)
No description available.
|
26 |
Esterases as indicators of exposure of birds to pesticidesThompson, H. M. January 1988 (has links)
No description available.
|
27 |
Cyclist exposure to traffic pollution: microscale variance, the impact of route choice and comparisons to other modal choices in two new zealand citiesPattinson, Woodrow January 2009 (has links)
This study aimed to investigate various aspects of cyclist exposure to common urban air pollutants, including CO, PM10, PM2.5, PM1.0 and UFPs. The initial part of the study compared cyclist exposure to that of other transport modes, while the second part addressed the implications of route choice. The final part analysed the effect of proximity to traffic. Data was collected in Christchurch and Auckland cities over a nine week period, with a total of 53 inter-modal and 7 separate cyclist sampling runs completed. Mobile sampling was conducted using a collection of instruments in four portable kits. Fixed-site meteorological data was used to find associations between pollutants and temperature and wind speed. Spatial patterns were also considered by means of time-series comparative graphs and colour-coded pollutant concentration GPS mapping. The cyclist mode was up to 61% less exposed than the car for primary pollutants (CO and UFPs), but up to 26% more exposed for PM1.0-10. The bus was generally the most exposed for all pollutants apart from CO. The effect of route choice was substantial, with the off-road cyclist route recording a reduction of 31% for CO and PM1.0, and 53% for UFPs while PM10 was 6%. At a distance of 7 m from traffic, exposure dropped by 30% (UFPs), 22% (CO) and 14% (PM2.5). At 19 m, concentrations decreased a further 17%, 13% and 8%, respectively. When moving much further away from traffic (~700 m), the effect was far less pronounced and no difference was observed for CO past 19 m. Conclusions suggest that for most pollutants studied, the cyclist mode faces much lower exposure than other modes, especially when traveling through backstreets and cycle tracks. Significant exposure reductions can also be made when only a very small distance away from traffic emissions. This has positive implications for health, sustainable city planning and active-mode transport promotion.
|
28 |
An Assessment of the Contribution of Micro-scale Activities to Personal Pollution Exposure in Commuting MicroenvironmentsShrestha, Kreepa January 2009 (has links)
Exposure to traffic pollution has become an increasing concern to public health. A number of studies have demonstrated that the air people breathe in while in transportation is particularly unsafe due to the high concentrations of carbon monoxide (CO), suspended particles (PM10, PM2.5 and PM1) and ultrafine particles (UFPs). Some studies have suggested that peak exposures of approximately one hour- a typical time spent in a transport micro-environment- may have more damaging health effects than the 24- hour sampling times current standards apply to Despite the widespread interest in health effects from exposure to traffic pollutants, there is a distinct lack of research of this kind in New Zealand. The research presented in this thesis was designed to assess the effect of traffic emissions on personal exposure. More specifically, this project intended to examine how exposures differed on different modes of transport and also to investigate the extent to which transport micro-environments such as car parks, bus stops and metro stations contributed to personal exposure levels. This study is the first of its type in New Zealand, which simultaneously monitored CO, PM and UFP concentrations in the transport micro-environment. Vehicular traffic emissions were shown to be a significant source of air pollution in populated urban areas, especially in the transport microenvironment. This results of this study showed that the mode of transport is a significant determinant of personal exposure to pollutants. The information gathered indicated slightly different results for Christchurch and Auckland, possibly due to variations in background levels, traffic counts and meteorological conditions at the time of monitoring. Results from the research also showed that built transport microenvironments could experience extremely high levels of pollutant exposures. Although commuters spend a relatively short time in such environments, such short-term peak exposures could contribute significantly to adverse health effects. The results presented here have relevance for both public health and for policies aimed at reducing human exposures to traffic-related air pollution. It is imperative to incorporate policies which ensure that such built environments are as safe as possible in terms of keeping exposure levels at a minimum.
|
29 |
Non-industrial personal benzene exposure in a mediterranean climateAnthonyhorton@bigpond.com, Anthony Horton January 2006 (has links)
Benzene is a volatile organic air pollutant that is ubiquitous in the environment. It is frequently reported in urban airsheds, principally as a result of evaporative emissions from motor vehicles. Increasingly stringent fuel quality standards have resulted in lower mean benzene concentrations in many urban airsheds, however the concentrations reported indoors can be higher than those in urban airsheds. Mean indoor benzene concentrations can reach one order of magnitude higher than those reported in urban airsheds. Long term exposure to very high benzene concentrations can result in leukemia, however the health risks of long term non-industrial exposure in the general public are currently uncertain.
An important part of determining the risks of non-industrial benzene exposure is to first determine the influence of various activities on 24-hour personal benzene exposure. Previous research has identified commuting in a private motor vehicle and refuelling with low benzene fuel as statistically significant contributors to nonindustrial benzene exposure in the Northern Hemisphere, however none has quantified the increase in benzene exposure as a result of these activities over a 24-hour period in the Mediterranean climate. The results of the 1987 TEAM study in the South Bay section of California reported that automobile exhaust was a significant contributor to non-industrial benzene exposure based on exhaled breath concentrations (p<0.05) and commuting in a private vehicle (p=0.0003) and refuelling (0.05) were important contributors based on personal benzene exposure concentrations (Wallace et al., 1988).
The aims of this thesis were to identify the roles and importance of selected activities in personal exposure to benzene, to determine the increase in 24-hour personal benzene exposure attributable to these activities and quantify the risk posed by these activities in a Mediterranean climate. In particular, the aim of this thesis was to investigate whether commuting in a private motor vehicle and refuelling are significant contributors to non-industrial personal benzene exposure in a Mediterranean climate, or whether lifestyle and climate interact.
This research was composed of a personal exposure study, a source monitoring study and a risk assessment. A cross-sectional personal exposure study was conducted for two reasons. Firstly, to quantify the mean personal benzene concentrations to which a representative sample of the general public of Perth was exposed as a result of their daily activities and behaviours. Secondly, to quantify the frequency of commuting by private motor vehicle and refuelling with low benzene fuel in Perth. Fifty participants were recruited for the personal exposure study, and asked to wear a monitor for 24-hour period(including weekends) in summer and winter and record their activities and locations in a diary. Prior to the monitoring they were asked to complete a questionnaire seeking background information on their home, lifestyle and behaviours. The results of the research revealed that there was not a statistically significant difference between the personal benzene exposure concentrations in summer and winter. An analysis of the questionnaire and time activity diary data using a generalised linear mixed model revealed that the time spent commuting in a private motor vehicle (â= 0.281, p<0.0001) and refuelling with low benzene fuel (â = 0.194, p=0.033) were statistically significant contributors to non-industrial benzene exposure. Each hour spent commuting resulted in a mean increase in 24-hour personal exposure of 0.74 ìgm-3 (â= 0.729 ìg m-3, p< 0.0001). The mean increase in exposure per hour of commuting in a private motor vehicle was larger in winter (â= 0.8 ìg m-3, p=0.008) than summer (â= 0.67 ìg m-3, p=0.004). Refuelling increased personal exposure by 1.50 ìg m-3 (1.49, p<0.0001) in each 24-period when refuelling was reported.
Benzene source monitoring was conducted at selected locations in Perth for two reasons. Firstly, data quantifying non-industrial personal benzene exposure during refuelling and commuting in a private vehicle in Perth was needed, and secondly, to make an assessment of risk attributable to these activities.
Benzene source measurements were conducted in two carparks in the Central Business District (CBD), in the vicinity of the northbound and southbound lanes of the Kwinana Freeway, and at a petrol station. The 7- day arithmetic mean benzene concentrations in the carparks were 4.49 ìg m-3 and 1.23 ìg m-3. The 7-day mean benzene concentrations northbound on the Kwinana Freeway was 2.78 ìg m-3, and the mean benzene concentration southbound was 2.57 ìg m-3. Benzene emissions in the carpark and on the Kwinana Freeway were measured during vehicle idling, which is representative of vehicle speed during heavy vehicle traffic. Benzene emissions at the petrol station were monitored in the vicinity of the petrol bowser, which is representative of emissions during refuelling. The 24-hour mean benzene concentration at the petrol station bowser was 38.15 ìg m-3.
The results of this research revealed that refuelling and commuting in a private vehicle are the most significant contributors to non-industrial benzene exposure in Perth, and that the contribution of these two activities in Perth is far greater than in previous published research, on the basis of the results obtained from the generalised linear model. The results of this research quantified the increase in non-industrial benzene exposure from refuelling and commuting in a private motor vehicle in a Mediterranean climate for the first time, and quantified the lifetime excess cancer risk attributable to these activities in a Mediterranean climate for the first time. The lifetime excess cancer unit risks of these two activities in a Mediterranean climate were 7.4x10-5 or 7.4 per 100000 population for commuting and 15.03 x 10-4 or 15 per 10000 for refuelling.
|
30 |
Environmental monitoring and biomonitoring of human arsenic exposureMiddleton, Daniel January 2016 (has links)
This study investigated human exposure to inorganic arsenic (As), a risk factor for cancer and non-cancerous health effects, in Cornwall, UK - a region of elevated environmental As resulting from naturally occurring mineralisation and historical mining. Recent exposures to As from private water supplies (PWS) were detected by measuring As in drinking water samples (n=127) and urine samples (n=207). Exceedances of the WHO 10 As µg L-1 guidance value were measured in drinking waters from 5 % of households. The Spearman correlation calculated for drinking water versus unadjusted total urinary As concentrations was 0.36. Urinary As speciation was used to distinguish between environmental inorganic As exposure and non-toxic dietary sources. Seafood derived urinary arsenobetaine exclusion and osmolality hydration adjustment yielded an improved correlation of 0.62 between drinking water and urinary As concentrations. Urinary hydration adjustment methods were improved and comparatively assessed using data from the US National Health and Nutrition Examination Survey (NHANES). Correlations of urinary concentrations of As, iodine (I), lead (Pb) and cadmium (Cd) against urinary flow rate (UFR) (low correlations desired) and urinary Pb and Cd against respective blood concentrations (high correlations desired) were used as independent performance criteria. Osmolality adjustment and a modified UFR-based adjustment method using empirically derived coefficients (slopes of analyte concentrations as a function of UFR) generally performed better than creatinine, excretion rate and bodyweight-adjusted excretion rate methods. The findings demonstrated the analyte specific nature of adjustment methods, their misuse in the literature and suggested a pathway to a more robust adjustment framework. Prolonged exposure to As from PWS was identified by the stability of 127 drinking water As concentrations measured up to 31 months apart. Drinking water As concentrations were correlated with those measured in toenails (Pearson's r: 0.53; n=200) and hair (Pearson's r: 0.38; n=104). The successful elimination of external contamination of toenail samples was indicated by low As concentrations in final-stage rinse solutions (geometric mean contribution: 0.4 %). A positive association between seafood consumption and toenail As and a negative association between home-grown vegetable consumption and hair As was observed when As in drinking water was < 1 As μg/L. Elevated As concentrations measured in residential soil (12-992 mg kg-1; n=127) and household dust (3-1079 mg kg-1; n=99), particularly on mineralised geological domains and in the vicinity of former As mining sites, were indicative of additional As exposure routes. Bioaccessibility-adjusted assessment criteria of 190 (13 % bioaccessibility) and 129 (23 % bioaccessibility) As mg kg-1 were derived and 10 and 17 % of residential soils were in exceedance, respectively. The relative importance of different exposure routes in the study region, namely whether As intake from soil and dust is evident in the study population, will form the basis of further work. This will be addressed using multivariate analyses of drinking water, soil and dust in conjunction with urine, toenail and hair As concentrations.
|
Page generated in 0.0319 seconds