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Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1983. / Bibliography: leaves 252-259. / Microfiche. / xv, 259 leaves, bound ill. 29 cm

The biological half-life of inorganic mercury in the Dungeness crab, Cancer magister Dana, was determined experimentally to be about 25 days. Crabs were exposed to mercury solutions, sacrificed after varying periods of time, and mercury determinations of whole body homogenates made with an atomic absorption spectrophotometer. The simple and widely used negative exponential equation for calculating biological half-life was not entirely adequate for describing the mercury elimination process. A better description was obtained using a nonlinear least-squares fit of an equation describing elimination at different speeds from two types of tissues. A further model allowed for recycling of mercury that was eliminated, and gave marginally better descriptions in some cases. / Science, Faculty of / Zoology, Department of / Graduate

The method for the determination of total mercury in biological material described in this paper comprises a destruction of organic matter by wet digestion, a reduction of the mercury by stannous sulfate, and circulation of the displaced mercury vapor in a closed system directly connected with an atomic absorption spectrophotometer Seven tissues from ten samples of locally obtained Roccus saxatilis (striped bass) were analyzed, and a three-fold elevation of mercury levels in the liver over the levels in the filet noted. See Table XIX for a comparison of the high, low, and average values for each tissue.

Master of Dental Surgery / The safety of amalgam restorations has been challenged, claims having been made that health risks are associated with the constituent mercury. There are assertions that mercury released from amalgam produces mercury poisoning, and is thus responsible for diverse symptoms of impaired health as well as disease states such as Multiple Sclerosis. This study examines the various forms of mercury and their effects and attempts particularly to delineate the significance of dental amalgam as a factor in hypersensitivity reactions and in the human body burden of mercury. Dental personnel are evaluated as a potentially high-risk group for mercury exposure. Dental amalgam and alternative restorative materials are considered, the removal of amalgam being evaluated as a therapeutic modality. The “anti-amalgam” perspective is scrutinised and the validity of the claims assessed. A review of the scientific literature, and the statements of national and international dental and scientific literature, and the statements of national and international dental and scientific organisations reflect the general support for the safety of dental amalgam. There is no evidence that health risks are associated with the use of dental amalgam other than rare local allergic reactions and oral lichenoid lesions. Notwithstanding the usefulness and safety of dental amalgam certain recommendations and conclusions are made in respect of future approaches to the utilisation of this material and for mercury in general. Further objective scientific research is necessary to determine the effects on human health of chronic exposure to low levels of mercury. There is the need for accurate general population threshold levels to be established for mercury vapour with special consideration for the vulnerable members of the community. The health professions have a significant role to play in providing informed opinion and advice for their patients and the public, in countering the more eccentric claims of the anti-amalgamists and assuaging the anxiety and confusion which accompanies this subject.

Master of Dental Surgery / The safety of amalgam restorations has been challenged, claims having been made that health risks are associated with the constituent mercury. There are assertions that mercury released from amalgam produces mercury poisoning, and is thus responsible for diverse symptoms of impaired health as well as disease states such as Multiple Sclerosis. This study examines the various forms of mercury and their effects and attempts particularly to delineate the significance of dental amalgam as a factor in hypersensitivity reactions and in the human body burden of mercury. Dental personnel are evaluated as a potentially high-risk group for mercury exposure. Dental amalgam and alternative restorative materials are considered, the removal of amalgam being evaluated as a therapeutic modality. The “anti-amalgam” perspective is scrutinised and the validity of the claims assessed. A review of the scientific literature, and the statements of national and international dental and scientific literature, and the statements of national and international dental and scientific organisations reflect the general support for the safety of dental amalgam. There is no evidence that health risks are associated with the use of dental amalgam other than rare local allergic reactions and oral lichenoid lesions. Notwithstanding the usefulness and safety of dental amalgam certain recommendations and conclusions are made in respect of future approaches to the utilisation of this material and for mercury in general. Further objective scientific research is necessary to determine the effects on human health of chronic exposure to low levels of mercury. There is the need for accurate general population threshold levels to be established for mercury vapour with special consideration for the vulnerable members of the community. The health professions have a significant role to play in providing informed opinion and advice for their patients and the public, in countering the more eccentric claims of the anti-amalgamists and assuaging the anxiety and confusion which accompanies this subject.

The objective of this research was to examine whether the United States and Canada have successfully implemented their Great Lakes Water Quality Agreement and to identify the factors determining the continuation of any injury to human health from pollution of the boundary waters. The Agreement was first negotiated in 1972 as part of the legitimation of the social unrest of the 1960s and gave special responsibilities to the International Joint Commission to advise the Parties of problems of water quality. It has been subject to periodic review and occasional renegotiation and amendment. Specifically, the Agreement was renegotiated in 1978 to address the health effects from the imperceptible exposures to persistent toxic substances. Though extensive scientific evidence of continuing injury to health from persistent toxic substances has been available, there has been a consistent pattern of deliberate failure by the authorities to report the injury and to implement many of the remedial provisions contained in the Agreement. The thesis claims that the failure of the International Joint Commission to advise the Parties of the new information about the injury to health and the failure of the Parties to act upon the information when it was obtained from other sources constituted dereliction of duty. While synthesis of the science linking the pollutant-induced injury to specific causal agents was necessary to provide an empirical measure of the failure to implement the Agreement, consideration of the social, economic and political aspects was needed to provide a sufficient explanation for the failure of the International Joint Commission to inform and of the authorities to act. There have been active attempts to use diversionary reframing of the Agreement, based on a multi-causal ecosystem theory proposed by fisheries ecologists, to attenuate the risk message and transform the Great Lakes Water Quality Agreement into a more inclusive and less focused agreement on restoring ecosystem integrity. This has been welcomed by industry and governments as a means to remove the focus from addressing the unresolved dangers of persistent toxic substances through costly remedial actions. The International Joint Commission undermined its credibility when it recommended ‘sunsetting’ the use of chlorine in chemical manufacturing. The Parties failed to use a precautionary approach to prevent the commercial introduction of new persistent toxic substances, such as the brominated flame retardants. Since the 1980s, the economic politics of the two nations have been profoundly influenced by neo-liberalism and one of the consequences has been the removal of environmental health as a priority from the respective political agenda. Advisory bodies seem to have been captured not only by the prevailing neo-liberalism but also by corporate interests and these factors seem to underlie the reluctance to report the injury to health from exposures to persistent toxic substances. Though there were many different health endpoints affected by exposures to water pollutants in the Great Lakes, the thesis concentrated on the evidence of neuro-teratogenic effects. The adequacy of the implementation of the Agreement during the past thirty-three years was tested by using Health Canada data on cerebral palsy hospitalisation to evaluate whether there were indications of previously undetected outbreaks of congenital Minamata disease in human populations in Canadian Great Lakes communities potentially exposed to methyl mercury from natural sources or from historic industrial uses of mercury. The uncertainties in the apparent association that was found were reduced by the application of Hill’s guidelines. While these findings indicated both the need for further multi-disciplinary research to locate and diagnose the victims and for a precautionary approach to the consumption of Great Lakes fish, they also indicated that, for more than three decades, health authorities have not diligently implemented the Agreement. The inclusion of the social, economic and political considerations in the forensic audit has revealed the dangers inherent in any renegotiation of the Great Lakes Water Quality Agreement.

A 17.1 Kb genetic element encoding for mercury resistance (OCT-Hg^r) was shown to translocate from its original location on the OCT plasmid to the resistance plasmid, RPl, in Pseudomonas putida. Analysis of RPl-Hg^r recombinant plasmids revealed that insertion of mercury resistance genes into RPl could occur at a variety of sites, with all recombinants having common EcoRI restriction fragments of 9.4, 3.8, 2.3, and 1.6 Kb, derived from the insertion. Hybridization analysis suggested the existence of extensive homology between this insertion and the prototypic mercury resistance transposon, Tn501, as well as the location of a similar merA sequence. Although the overall size was shown to be quite different from Tn501, striking physical similarities are shared between these two elements.

Translocation of a 17.1 kilobase region of the OCT plasmid encoding mercury resistance (mer) in Pseudomonas putida was shown to occur in a recombination-deficient host with plasmid PP1 serving as a recipient replicon. The frequency of transposition in Pseudomonas was estimated at 10^3 -10 -^2, but undetectable in Escherichia soli. ' DNA comprising all of mr as well as subregions there of were cloned and subjected to DNA sequence analysis. Like other transposons, mer was found to contain inverted repeat sequences at its termini. These were similar to, but not identical to the inverted repeat structures found in the prototypical mercury resistance transposon Tn501 from E. aeruginosa.