Aquatic organisms experience intermittent exposure to contaminants. The hazard from such discontinuous exposure may not simply be predicted from existing continuous exposure. Little is known about the bioaccumulation responses of shellfish to metals during intermittent compared to the continuous exposure counterparts. This study was designed to compare the bioaccumulation responses of two metals (Cd and Hg) singly (Chapters 3 and 4) or mixtures (Chapters 5 and 6) during continuous and intermittent exposure. Responses were examined using a multi-assay approach in areas of oxidative stress, osmoregulation, haematology and organ pathology. Tissue metal concentrations were highest in the gill and digestive gland for both metals. The linear or curvilinear pattern of accumulation was observed in the continuous exposure. While an alternating temporal uptake and clearance corresponding with the exposure was observed in the gill (Hg alone) and haemolymph (Cd alone) in intermittent profile. At the end, the study shows that accumulation of Hg or Cd was less in the intermittent compared to the continuous exposure for most tissue. Sub-lethal responses during Hg or Cd alone were similar in both regime apart from the severe pathology in the gill (continuous exposure) and inflammation in the digestive gland (intermittent exposure) observed in the Hg alone treatment (Chapter 4). For Hg plus Cd mixture, the additive effect in accumulation was observed in both exposures. Sub-lethal responses during mixtures were not affected in the intermittent. However, an antagonistic interaction was observed in the TBARS during continuous exposures for all tissues apart from the digestive gland. In terms of risk assessment, regulations for the single metals in continuous exposure will be protective for intermittent events at least for adult M.galloprovincialis.

<p>Arsenic (As) exposure via groundwater consumption is a global health problem affecting millions. Monitoring exposure is a key step in understanding and predicating future health outcomes. This thesis explores the relationships between arsenic concentrations in toenails and arsenic in water. Three case studies were investigated, with residents from: North Carolina, USA (n=103); the Rift Valley, Ethiopia (n=60); and the Mekong Delta, Vietnam (n=65). Arsenic concentrations above the WHO's recommended 10ppb limit were found in groundwater from the three research sites. </p><p>Arsenic in toenails was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). </p><p>In the Rift Valley of Ethiopia, 53% of the tested drinking wells (n=34) had As above the WHO's limit. Arsenic concentrations in toenails (n=60) were significantly correlated to As concentrations in groundwater (r=0.72; p<0.001), reflecting the direct exposure of rural communities to As in well water, which is their principle water source. Male minors (<18 years old) were found to have greater nail-As concentrations compared with adults consuming equal amounts of As (p<0.05). Estimated As dose specifically from drinking water sources was also associated with nail concentrations (p<0.01). </p><p>In the Mekong Delta of Vietnam (Dong Thap Province), 36 out of the 68 tested wells had As content above the WHO's recommended limit of 10ppb, with levels as high as 981 ppb. Arsenic contents in nails collected from local residents (n=62) were significantly correlated to As in drinking water (r=0.49, p<0.001). Demographic and survey data show that the ratio of As in nail to As in water varies among residents that reflects differential As accumulation in the exposed population. The data show that water filtration and diet, particularly increased consumption of animal protein and dairy and reduced consumption of seafood, were associated with lower ratios of As in nail to As in water and thus could play important roles in mitigating As exposure.</p><p>Sixty-one wells were tested from Union County, North Carolina, with 15 out of 61 wells exceeded the WHO's 10 ppb limit. Arsenic values ranged from below the limit of detection (0.07) to 130ppb, with a mean of 11ppb (median=1.5ppb). Nails were collected from county residents (n=103) and were statistically correlated with As-water concentrations (r=0.48, p<0.001). </p><p>Integration of the data from the three cases studies across different populations and ethnicities show high correlation between As concentrations in groundwater and As in nails in all the three locations (r(Union County)= 0.48, p<0.001; r(Ethiopia)=0.72 p<0.001; r(Vietnam)=0.49, p<0.001). For As-nail to As-water pairs in which As in water was above 1ppb, these three locations are statistically indistinguishable from one another (r=0.62, p<0.001, n=176). These results support the hypothesis that nails can be used as a biomarker of exposure regardless of geographic or ethnic differences in populations considered. Nutrition (meat, seafood, and milk consumption) rather than gender, ethnicity, or dose is suggested to be the major confounding issue affecting the magnitude of As exposure in the human body.</p> / Dissertation

Most firms are actively assessing the financial risks exposure and do determine a policy for the hedging activities. It is not solely the risk aversive attitude from the managers that need to be overlooked, but to provide sufficient information to the shareholder is desirable for minimizing the gap of information asymmetry, which is by itself considered a tool for value creation (Bergstrand et al. 2009:45-47). To narrow this gap, listed Swedish companies have since 2005 been required to disclose their financial risk in their Annual Reports.  By using a quantitative approach the researcher will review the financial risk note in Annual Reports of 2008 to identify characteristics and determinant variables on firms depending on whether they utilize currency derivatives or not. An independent two-sample t-test has showed statistical significance that there difference of the means regarding size, FX exposure and leverage between users and non-users of currency derivatives. The means of currency derivatives users were higher for Size and FX exposure, while lower for leverage. A positive correlation between a firm’s size and FX exposure was found, suggesting that the determinant for hedging FX exposure could be explained by the size of the firm and vice versa.

<p>This study was an attempt to replicate the positive results of a precognitive habituation (PH) experiment devised by Bem (2003). The procedure is based on the subliminal mere exposure (SME) design. In an SME procedure subjects are exposed to image-pairs in a preference task, after being exposed to one of those images (the target) subliminally. The target is preferred significantly more often due to the mere exposure effect. In the PH procedure the preference task precedes the exposure and images are of negative and erotic valence. It was hypothesized that due to exposure (in the future), subject preference will increase for negative and decrease for the erotic target images, especially for subjects classified erotically or negatively reactive (Bem, 2003). Also, that an overall (negative and erotic) effect would be shown. The results were not significantly above chance expectation for any of the hypotheses (50.0%; 47.2%, p = .149; 50.8%, p = .279).</p>

<p>An extensive use of chemicals in countless consumer products has resulted in human exposure to several persistent organic pollutants (POPs). Sufficient knowledge about their chemical composition properties and environmental faith is required, to be able to proper risk assess and regulate the substances. Significant data gaps exist regarding knowledge of actual exposure to humans and toxicological effect data.</p><p>The objective of this thesis was to add human exposure data of a few POPs from four case studies. The analytes discussed in this thesis are polychlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD).</p><p>Three European populations were studied. Milk was analysed from a group of women, who were accidentally exposed to high levels of 2,3,7,8-TetraCDD (TCDD) in Seveso, 1976. Still today, twice as high TCDD levels were recorded in the milk, compared to background concentrations. Serum was analysed from mothers and their infants from The Netherlands. Cord serum contained equal amounts of POPs as in mother’s blood, indicating non-hindered placenta transfer. Serum analysed from Swedish men and women with a high fish intake had elevated PCB and PCB metabolite (OH-PCB) levels. Additionally, butter was collected worldwide and shown to be a suitable matrix for dairy product survey of POPs.</p><p>The exposure levels in the four papers were compared to recently reported exposure levels in Europe. It is indicated in the thesis that the PCDDs/PCDFs and PCBs toxic equivalency (TEQ) levels are of concern, i.e. the ratio between threshold levels for adverse health effects and TEQ exposure levels is lower than requested margin of safety. Average levels of PBDE/HBCDD in the European population are estimated to be of no concern today, but for individuals with intakes at the 95th percentile are the current margins of safety small.</p>

This thesis presents the findings of a combined geomorphological, sedimentological and geochronological investigation into the glacial history of the Clearwater Basin, Mid Canterbury, New Zealand. The study demonstrates that a thick wedge of glacial and paraglacial sediments are preserved in the valley. These are >100m thick and preserve evidence of at least 3 glacial phases (>180ka). The study presents a new and detailed geomorphology map for the Clearwater valley and adjacent areas and has added 17 new recessional positions to the local glacial record. Surface Exposure Dating (SED) has been used to directly date the moraines of the Clearwater Basin providing the first detailed chronology for glacial moraine in this area. In total 31 cosmogenic ages from 9 separate moraines are presented. The results demonstrate that the LGM advance is the Trinity moraine of Mabin (1980) and not the Hakatere moraine as previously assumed and that the LGM was achieved at or about 23ka. The Clearwater glacier receded up valley between 23 and 13ka with some indication of accelerated retreat after c.16ka. The correlation to the adjacent Lake Heron Valley is also revised.

Previous research into the subsequent effects of prenatal methadone exposure has primarily focused on neurological changes and short term physical development. While there have been some studies of behavioural development, only short term effects have been investigated. The present research therefore aimed to assess longer term behavioural development of offspring exposed to methadone gestationally, lactationally or both. Methadone was provided in the drinking water of drug-treated rat dams during gestation (2.39mg/kg/day) and lactation (2.86mg/kg/day). The four conditions were: non-exposure/control (N = 24), gestational-exposure (N = 20), lactational-exposure (N = 24), and combined-exposure (N = 21). As well as several measures of pregnancy characteristics, offspring postnatal physical development was assessed at 30, 60 and 120 days after birth. Behavioural assessments were also made at these ages by means of an open-field, Y maze and emergence apparatus. There were no significant differences in physical development. Maternal methadone exposure during gestation reduced the number of rat dams that became (or remained) pregnant. In the offspring, there was increased activity in lactationally-exposed rats through into adulthood. Anxiety was increased in the combined-exposure condition, primarily in adolescent males. The significant longer term effects of earlier methadone on the rats’ behavioural development supported the need for more research into this hitherto relatively neglected area. More information about effects of methadone exposure on anxiety and activity, as well as on social functioning and motor coordination could be useful for understanding potential risk factors in the ever growing methadone-exposed population, and thus suggesting best practice for methadone maintenance programmes.

A role for gene variants in regulating the pharmacokinetics of systemically available toxicants has not yet been established. A panel of 18 genetically-diverse inbred mouse strains was used to determine the range of total exposure kinetic parameters in blood and bone marrow following a single oral administration of benzene (100 μg/kg) to male and female mice. Large ranges in several pharmacokinetic parameters were found when data from blood and bone marrow were analyzed. AUC and CL_F pharmacokinetic parameters in blood and bone marrow pharmacokinetics were strikingly different as were these parameters in males and females. Final clearance (CL_F) was found to be the most statistically robust pharmacokinetic parameter as it accounted for exposure of the matrix (AUC) and normalized for dose variations among the strains. The CL_F values in blood and bone marrow used for haplotype association mapping showed 331 and 164 quantitative trait loci with statistical significance, respectively (male mice; -logP>4). Two loci were found to be shared between males and females QTL bone marrow data sets and one common locus was found for male blood and bone marrow data. No overlap was found among blood QTL in males and females (or between blood and bone marrow data from females). Protein and mRNA expression data for the primary benzene-metabolizing enzymes CYP2E1 and UGT1A6 showed very little strain-dependent variation. Strain dependent differences in mRNA levels of NQO1 and MPO were small but statistically significant, as were those for GAPDH and β2-microglobulin. These data demonstrated that polymorphisms with the greatest contribution toward overall variations in systemic exposures occurred in genes encoding for non-metabolic proteins. While exposure does not equate to toxicity, identification of the genes regulating distribution and clearance may be useful for investigating host susceptibility to toxic effects following benzene exposure. This research was supported in part by the NIEHS NTP Grant N01ES45529, NIEHS Toxicology and Toxicogenomics Training Grant (5T32ES007091-29), NIEHS/NTP Division of Intramural Research, and Southwest Environmental Science Center Grant P3ES06694.

Background: Arsenic (As) is a naturally-occurring element with known toxicant effects. The primary exposure pathway is through ingestion, but the overall contribution of food versus water and the impact of specific dietary nutrients on urinary As excretion is not well understood. Methods: Secondary analyses of laboratory results from food, water and urine samples, questionnaire and anthropometric data, and dietary records were performed on four study populations: the National Health Exposure Assessment Survey (NHEXAS)-Arizona, Arizona Border Survey (ABS), the Arizona sub-group of the Binational Arsenic Exposure Survey (BAsES), and the 2003-2004 National Health and Nutrition Examination Survey (NHANES). Dietary As intake was measured in duplicate food samples and/or modeled from dietary records for each population using the U.S. Total Diet Study (TDS) arsenic residue database and a published market basket survey. Urinary total As, As⁵, As³, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were analyzed, and sum of species As was calculated as the sum of As⁵, As³, MMA and DMA. Regression analyses modeled the relation between urinary As biomarkers (total, sum of species, MMA:sum of species, and DMA:MMA) and dietary As, adjusted for drinking and cooking water As intake, current smoking, sex, age, ethnicity, body mass index, and nutrient intake. Results: Modeled dietary As based on TDS mean As residue data greatly underestimated exposure as compared with measured As in duplicate diet samples and estimates based on other residue data. Dietary As was a significant predictor of urinary total As in all four populations, of sum of species As in both BAsES and NHANES, and of %MMA and DMA:MMA in NHANES. Dietary protein intake was associated with decreased sum of species As in both BAsES and NHANES, but dietary folate was not. Conclusions: Dietary As contributes a markedly greater proportion of total ingested As and is a better predictor of urinary As than water As intake in the U.S. Among subjects who did not consume seafood, total As exposure from food and water exceeded the provisional tolerable daily intake of 2.1 µg/kg body weight/day in 3-15% of these study populations. Increased protein intake may mitigate the effects of As.

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