The Effect of Plastic Tarps on the Rate of Human Decomposition During the Spring/Summer in Central Texas
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Forensic anthropological literature cite that bodies are commonly covered or wrapped in man-made materials for disposal and concealment. Therefore, knowing if there are differences in the rate of decomposition between tarp and control bodies is important for forensic scientists conducting postmortem interval estimations. While several studies have been conducted on the effects of decomposition when the body is covered or wrapped in materials such as clothing, blankets, and plastic tarps, most of these studies have examined a variety of coverings simultaneously with relatively small sample sizes and use pig surrogates. Therefore, the purpose of this study is to conduct a controlled investigation of the effect of plastic tarps on the rate and pattern of human decomposition in Central Texas using a relatively large sample size. Unlike previous studies, this study utilized only one type of covering, the sample size was larger than previously examined, and environmental conditions and dates of death are known. Human remains covered or wrapped in a tarp provides an ideal environment for decomposition since the tarp may maintain moisture and temperature while providing insects and bacteria protection from predators and environmental factors. Therefore, it was hypothesized that the plastic tarp would aid in decomposition in two ways: 1) by increasing the activity of necrophagous insects, which prefer a warm, shaded and outdoor environment and 2) by increasing putrefaction caused by bacteria that require an aqueous medium. The increased activity of insects and bacteria should therefore likely increase the rate of decomposition. In other words, require fewer accumulated degree days (ADD) to reach each stage of decomposition. This study showed that remains wrapped in plastic tarps had a statistically significant effect on the rate of human decomposition when compared to unwrapped remains in a Central Texas environment. Since the null was rejected further examination occurred and found that temperature was not a significant contributing factor for the change in rate of decomposition. However, insect activity was observed as a contributing factor since it was a constant throughout the entire study period for all wrapped remains. This study will contribute to the field of forensic anthropology by providing reliable information about the effect wrapping bodies in plastic tarp material has on the decomposition rate in Central Texas. Law enforcement and other forensic scientists should be very cautious if using the Megyesi et al. (2005) method and be fully aware of its limitations and inconsistent results.