The formation of adipocere in aquatic environments

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NO FULL TEXT AVAILABLE. This thesis contains 3rd party copyright material. ----- The term adipocere refers to a waxy substance that is associated with dead bodies that have been under water, in moist soil or in other moist environments for prolonged periods of time. Adipocere is comprised of a mixture of saturated fatty acids that result from the late post mortem changes associated with the decomposition of adipose tissue in the body. In a forensic context, its presence becomes significant because of its ability to slow decomposition and, in some cases, preserve remains. The particular factors associated with aqueous environments on adipocere formation have been investigated. The aims were to determine the effect of these factors on the rate and extent of adipocere formation and the ability of these factors to characterise the chemical composition of this product. Interest in this decomposition product has been growing rapidly since the discovery of the "Iceman", a well preserved 5300•-year old corpse discovered in an Alpine glacier. Knowledge of adipocere formation is limited although most studies have focussed on its chemical components and microscopic properties. To date, no one has undertaken a systematic characterisation of its formation in both human and non-human tissue submerged in aquatic environments. Furthermore, its potential to be useful in a forensic context highlighted the need for a comprehensive analysis of adipocere formation in aquatic burial environments. In order to investigate this post-mortem product. a rapid and reliable method was created to separate and identify fatty acids present in adipocere. This involved the development and validation of a simplified solid-phase extraction-gas chromatography mass spectrometry method for the quantification of free fatty acids commonly found in adipocere. The method described in this study has comparable limits of quantification to the more sensitive methods previously reported in the literature for adipocere, but has significant advantages in that it has greater recoveries, is consistently reproducible, less complicated and less time consuming. This allows for the rapid and accurate determination of low levels of fatty acids in adipocere samples from an aqueous environment. The formation of model adipocere was used as the basis for experimental work involving the analysis of aquatic burial factors. Whilst human adipose tissue was obtained for this research, it was not possible to attain the quantity required to conduct a large scale systematic investigation. Instead, a comparison study was conducted between pig and human adipose tissue to determine the suitability of pigs to model human adipocere formation. The experiments reported were also designed to illustrate the changes in fat deposits of human and pig adipose tissue during the initial month of decomposition and, thereby, determine the chemical profile of early-stage adipocere formation. This work indicates that although pig adipose tissue is similar to human adipose tissue and therefore suitable to mimic human decomposition, some margins of error exist when comparisons are being made between the species. The formation of model adipocere allowed for the analysis of individual factors present in the burial environment and their effect on the rate of formation and composition of adipocere. The formation of adipocere within the control series, which acted as the benchmark for comparison with the other experiments is described. Those conditions known to favour adipocere formation; the complete submergence in a warm, anaerobic and aquatic environments, adequate skin and adipose tissue and sufficient bacteria were used in this research. The factors investigated included pH and the influence of various cations across the pH range, different types of water and the influence of temperature and body wrappings on adipocere formation. The majority of burial environments successfully formed adipocere at various stages of formation. Comparison with the control series allowed the various burial factors to be linked with either an acceleration or retardation of the decomposition process and, hence, the formation of adipocere. A field study was included in this research to address any differences associated with laboratory and field conditions. A comparison of field samples with experimentally created adipocere using water collected from the field site is described. Both human and pig adipose tissue was included in the study, which also allowed for an investigation of the variations associated with human and pig decomposition and subsequent adipocere formation. The study identified differences between the formation of adipocere from laboratory and field sites and between pig and human adipose tissue. The results emphasise the importance of using field sites and human tissue to simulate adipocere formation. The results of this research confirm previous field observations regarding adipocere formation in aquatic environments and identify new aspects of its formation which were previously unknown. The findings represent an important contribution to the field of forensic science by providing valuable insights into an area of decomposition in which limited research and knowledge exists.
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