Exposure dynamics of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in the food web of western Lake Erie and the Detroit River.

This thesis investigated the processes regulating the exposure dynamics of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the western Lake Erie and the Detroit River biota. First, the freshwater mussel, Elliptio complanata, was calibrated as a biomonitor of PAH and PCB water concentrations and used to assess bioavailable water concentrations along the Detroit River and western Lake Erie. Concentrations of the more hydrophobic PAHs and more water soluble PCBs were present at elevated concentrations at the Detroit Edison Generating Station, in the Trenton Channel. Elevated PAH concentrations were also detected at 3 other sites in the Detroit River. Since it was found that PAHs and PCBs were present at high concentrations in the water of the study region, the distribution patterns of PAHs and PCBs were further determined in 4 benthic invertebrate species of western Lake Erie. Overall, the results of this study suggest that many factors regulate the exposure dynamics of PAHs and PCBs in aquatic systems, such as chemical hydrophobicity, metabolic degradation, route of chemical uptake, and organism habitat, diet, feeding strategy, and lipid content. (Abstract shortened by UMI.)Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2000 .G49. Source: Masters Abstracts International, Volume: 40-03, page: 0668. Adviser: Douglas Haffner. Thesis (M.Sc.)--University of Windsor (Canada), 2000

The Development of Theory- and Evidence-based Educational Workshops for Occupational Therapists

The Do-Live-Well (DLW) framework is a health promotion approach developed by Canadian occupational therapists (OTs). As the DLW framework is relatively new, it has not been widely adopted by OTs. In order to facilitate OTs to incorporate the DLW concepts in their practice, there should be more learning opportunities, and online and in-person workshops have been chosen to be a specific interest of this study. The purpose of this project was to develop theory- and evidence-based in-person and online educational workshops for OTs as a pre-implementation study to increase the knowledge of the DLW framework among OTs. In order to develop workshops, we incorporated three different phases. First, we interviewed four OTs who have been applying the DLW concepts in practice to understand their use of the framework and training needs. It was identified that OTs experienced difficulty applying the DLW concepts in practice and wanted opportunities to learn more about the DLW framework. Next, problem-based learning (PBL) guided the workshop development, and the same eight key PBL principles were incorporated in both the in-person and online workshops. Finally, four different experts completed usability testing of the online workshop website to improve its learning environment. The online workshop website was improved based on the feedback from the usability testers. The next step of this research will be to compare effectiveness of in-person and online platforms for workshop delivery. The detailed development process described in this project may assist occupational therapy educators in developing theory- and evidence-based educational delivery methods

Resonant ion-pair formation in electron recombination with HF^+

The cross section for resonant ion-pair formation in the collision of low-energy electrons with HF^+ is calculated by the solution of the time-dependent Schrodinger equation with multiple coupled states using a wave packet method. A diabatization procedure is proposed to obtain the electronic couplings between quasidiabatic potentials of ^1Sigma^+ symmetry for HF. By including these couplings between the neutral states, the cross section for ion-pair formation increases with about two orders of magnitude compared with the cross section for direct dissociation. Qualitative agreement with the measured cross section is obtained. The oscillations in the calculated cross section are analyzed. The cross section for ion-pair formation in electron recombination with DF^+ is calculated to determine the effect of isotopic substitution.Comment: 12 pages, 12 figure

Are fish consumption advisories for the great lakes adequately protective against chemical mixtures?

Background: The North American Great Lakes are home to \u3e 140 types of fish and are famous for recreational and commercial fishing. However, the presence of toxic substances has resulted in the issuance of fish consumption advisories that are typically based on the most restrictive contaminant. Objectives: We investigated whether these advisories, which typically neglect the existence of a mixture of chemicals and their possible additive adverse effects, are adequately protective of the health of humans consuming fish from the Canadian waters of the Great Lakes. Methods: Using recent fish contaminant monitoring data collected by the government of Ontario, Canada, we simulated advisories using most-restrictive-contaminant (one-chem) and multi-contaminant additive effect (multi-chem) approaches. The advisories from the two simulations were compared to determine if there is any deficiency in the currently issued advisories. Results: Approximately half of the advisories currently issued are potentially not adequately protective. Of the four Great Lakes studied, the highest percentage of advisories affected are in Lake Ontario if an additive effect is considered. Many fish that are popular for consumption, such as walleye, salmon, bass and trout, would have noticeably more stringent advisories. Conclusions: Improvements in the advisories may be needed to ensure that the health of humans consuming fish from the Great Lakes is protected. In this region, total polychlorinated biphenyls (PCBs) and mercury are the major contaminants causing restrictions on consuming fish, whereas dioxins/furans, toxaphene, and mirex/photomirex are of minor concern. Regular monitoring of most organochlorine pesticides and metals in fish can be discontinued. © 2017, Public Health Services, US Dept of Health and Human Services. All rights reserved

Is it appropriate to composite fish samples for mercury trend monitoring and consumption advisories?

Monitoring mercury levels in fish can be costly because variation by space, time, and fish type/size needs to be captured. Here, we explored if compositing fish samples to decrease analytical costs would reduce the effectiveness of the monitoring objectives. Six compositing methods were evaluated by applying them to an existing extensive dataset and examining their performance in reproducing the fish consumption advisories and temporal trends. The methods resulted in varying amount (average 34-72%) of reductions in samples, but all (except one) reproduced advisories very well (96-97% of the advisories did not change or were one category more restrictive compared to analysis of individual samples). Similarly, the methods performed reasonably well in recreating temporal trends, especially when longer-term and frequent measurements were considered. The results indicate that compositing samples within 5 cm fish size bins or retaining the largest/smallest individuals and compositing in-between samples in batches of 5 with decreasing fish size would be the best approaches. Based on the literature, the findings from this study are applicable to fillet, muscle plug and whole fish mercury monitoring studies. Overall, compositing fish samples for mercury monitoring could result in a substantial savings (approximately 60% of the analytical cost) and should be considered in fish mercury monitoring, especially in long-term programs or when study cost is a concern

Are Chinese consumers at risk due to exposure to metals in crayfish? A bioaccessibility-adjusted probabilistic risk assessment

Freshwater crayfish, the world's third largest crustacean species, has been reported to accumulate high levels of metals, while the current knowledge of potential risk associated with crayfish consumption lags behind that of finfish. We provide the first estimate of human health risk associated with crayfish (Procambarus clarkii) consumption in China, the world's largest producer and consumer of crayfish. We performed Monte Carlo Simulation on a standard risk model parameterized with local data on metal concentrations, bioaccessibility (phi), crayfish consumption rate, and consumer body mass. Bioaccessibility of metals in crayfish was found to be variable (68-95%) and metal-specific, suggesting a potential influence of metal bioaccessibility on effective metal intake. However, sensitivity analysis suggested risk of metals via crayfish consumption was predominantly explained by consumption rate (explaining >92% of total risk estimate variability), rather than metals concentration, bioaccessibility, or body mass. Mean metal concentrations (As, Cd, Cu, Ni, Pb, Se and Zn) in surveyed crayfish samples from 12 provinces in China conformed to national safety standards. However, risk calculation of phi-modified hazard quotient (HQ) and hazard index (HI) suggested that crayfish metals may pose a health risk for very high rate consumers, with a HI of over 24 for the highest rate consumers. Additionally, the phi-modified increased lifetime risk (ILTR) for carcinogenic effects due to the presence of As was above the acceptable level (10(-5)) for both the median (ILTR = 2.5 x 10(-5)) and 90th percentile (ILTR = 1.8 x 10(-4)), highlighting the relatively high risk of As in crayfish. Our results suggest a need to consider crayfish when assessing human dietary exposure to metals and associated health risks, especially for high crayfish-consuming populations, such as in China, USA and Sweden.HZ by the National Natural Science Foundation of China (41273087). LN was supported by European Union Marie Curie Actions, Grant FP People 2010 “IRSES Electroacross” and BG by the SAGE-IGERT Fellowship (US National Science Foundation)