The Effect of Clothing on the Decomposition of Human Remains

Transcription

1 Article The Effect of Clothing on the Decomposition of Human Remains Robyn A. Capobianco 1 Angi M. Christensen 2 Abstract: The relation between clothing and the rate of human decomposition is still unclear despite previous research. Some suggest that clothing accelerates decomposition; others indicate that it may slow decomposition. The use of pig models in many of these studies may contribute to this discrepancy. Here we present the results of a pilot study that examined six clothed human cadavers at the University of Tennessee Anthropology Research Facility for a period of one year and compared observations with those documented for unclothed specimens at the same facility using a decomposition scoring approach along with accumulated degree days (ADD). More ADD were required for clothed specimens to reach later decomposition stages, though differences were not highly significant, suggesting that clothing may slow the rate of decomposition, at least in East Tennessee. The amount of clothing worn appears to have an effect. Introduction Accurate estimation of the postmortem interval (PMI) is often critically important to a forensic death investigation. Although early postmortem changes such as algor mortis, livor mortis, and rigor mortis can provide fairly accurate PMI estimates within the first few hours to days after death, estimates become more challenging and less accurate when decomposition (the combined processes of autolysis and putrefaction) becomes more advanced [1]. Part of the difficulty can be attributed to the numer- 1 Department of Integrative Physiology, University of Colorado at Boulder, Boulder, CO 2 Federal Bureau of Investigation Laboratory, Quantico, VA Received March 15, 2017; accepted May 22, (3), 2017 \ 379

2 ous intrinsic and extrinsic factors that affect the quality and rate of decomposition. The creation of outdoor human decomposition laboratories such as the Anthropology Research Facility (ARF) in Knoxville, Tennessee, and the Forensic Anthropology Center at Texas State (FACTS) in San Marcos, Texas, has improved our understanding of the nature and timing of human decomposition. For example, studies at the ARF have examined numerous variables affecting decomposition rate including temperature [2 5], burial depth [5, 6], body size [1, 6, 7,], water [5, 6], poisons [1, 2, 4, 8], trauma [1, 6], and scavenging activity [5, 6]. It is now well understood that temperature accounts for most of the variation in decomposition because of its relationship with both insects and bacteria [1, 9 11], but other factors are still significant. Clothing is one variable that has seen minimal attention and for which studies have shown mixed results. Clothing is a highly variable factor in many forensic death investigations, ranging from none to multiple layers of clothing or other wrapping. Although many studies of decomposition utilize unclothed human and nonhuman models, more than half of death investigations involve bodies that are clothed [12 14]. Therefore, it is critical to understand the effect of this variable on decomposition. There is also some debate about the relation between clothing and decomposition rate. Some researchers suggest that clothing may accelerate decomposition [6, 7, 15], because it provides a shelter for insect activity. Others suggest that clothing may slow decomposition [1, 16 18] by inhibiting insect access or preventing bloating. Clothing may also alter the decomposition environment temperature, thereby possibly affecting the microbial environment [19]. Here we present the results of a pilot study that directly compares decomposition rates of clothed and unclothed human remains under similar environmental conditions. 380 / 67 (3), 2017

3 Materials and Methods Six unembalmed, unautopsied adult human cadavers were used in this study: four white males, one white female, and one black male. All specimens were donated to the University of Tennessee Forensic Anthropology Center for scientific study and were of approximately average or normal body type (i.e., they were not visibly obese or emaciated body mass data for these specimens are not available). To approximate actual clothing that an individual may have worn, subjects placed in cooler months were outfitted with a cotton blend T-shirt, sweatpants, and a sweatshirt ( Cool ). Those placed in warmer months were outfitted with a cotton blend T-shirt and sweatpants only ( Warm ). All specimens were placed in a supine position. Demographics and placement conditions are shown in Table 1. Specimen Age Sex Ancestry Clothing Date of Placement 1 (4-01) Elderly Male White Cool 12 January (8-01) Male White Cool 24 January (10-01) Mid-70s Female White Cool 29 January (23-01) 80 Male White Warm 6 June (30-01) Male Black Warm 5 September (31-01) Mid-70s Male White Warm 15 September 2000 Table 1 Specimen demographics and placement conditions. The study began with the placement of the first specimen on January 12, During warmer months, observations were made daily. In the cooler months, observations were made every other day at a minimum, sometimes daily. Photographs were taken on all observation days. For each observation day, specimens were assigned a decomposition score ranging from I to IV corresponding to observations in Table 2 modified from Galloway et al. [16] Data collection in this study continued until Stage IV (skeletonization or mummification) was reached. Although the total body score method [20] has been shown to be a good model for assessing decomposition and estimating PMI, the data collected from the previous studies more closely resembles that of Galloway et al. [16], making it a more appropriate model for this study. Moreover, the total body score method requires being able to visually assess the torso and limbs, which cannot be accomplished accurately through clothing. 67 (3), 2017 \ 381

4 Stage I: Fresh Observations * No insect activity * No discoloration, except for lividity * Green discoloration of abdomen and marbling of extremities II: Early Decomposition III: Advanced Decomposition * Bloating of all body parts, from initial boating until maximum bloating or size is attained * Beginning of skin slippage on hands, arms, legs, and feet * Extensive maggot activity * Extensive insect activity, including flies, bees, some species of beetles, ants, and cockroaches * Caving in of thoracic and abdominal cavities due to the dissipation of gases, either through rupture of tissue, body orifices, or carnivore activity * Extensive maggot activity * Further destruction of soft tissue through autolysis and insect and carnivore activity * Skin slippage and hair loss * Dry bones IV: Skeletonization * Bones containing desiccated and mummified tissue * Various species of beetles present 382 / 67 (3), 2017 * Bleached and exfoliated bones (late stage) Table 2 Decomposition scoring stages and observations. Temperature data were recorded using combined reports from the ARF weather station and a nearby National Weather Service weather station located 16 km from the ARF. The two recordings typically deviated by only one or two degrees. A calibration estimate was calculated using both recordings to generate an average daily temperature, which was then used to calculate accumulated degree days (ADD). ADD are calculated by summing the average daily temperature of each consecutive day following death [3]. The ADD required to reach Stages II, III, and IV for each of the six specimens in this study were compared with similar data collected from unclothed specimens studied at this same facility during similar seasons [2, 3] using 2-sample t tests. Vass [3] placed seven unaltered human cadavers in the prone position during the months of January (1), February (1), May (1), August (3), and September (1). Watkins [2] placed three specimens in wire frame enclosures in a supine position in May, June, and October. Data from these studies were not recorded using the same scoring system, but they did contain detailed descriptions on specified dates. These descriptions allowed a

5 comparison to the stages in Table 2 and a determination of when specimens reached decomposition Stages II, III, and IV. Vass [3] recorded ADD for each documented day, and these data were used directly as the ADD at which specimens were determined to have reached each stage. For the Watkins [2] data, only average monthly temperature was recorded and was used to approximate the ADD for each stage. Results Images of specimens from the current study, taken on approximately the days on which Stages II, III, and IV were reached, are shown in Figures 1, 2, and 3, respectively. The ADD at which each specimen reached Stages II, III, and IV from this study as well as the Vass [3] and Watkins [2] studies are shown in Table 3 and Figure 4. The average is also presented for the current study of clothed remains, and a combined average was calculated for the unclothed specimens from the two previous studies. The average ADD required to reach each stage for clothed and unclothed specimens is also shown in Figure 5. To reach Stage II, significantly fewer ADD (p=0.003) were needed for the clothed specimens in this study compared to the unclothed specimens in the Watkins [2] and Vass [3] studies. This trend reversed for ADD required to reach Stages III and IV, where the ADD for clothed remains exceeded the ADD for the unclothed remains. Differences were not significant, though were much greater and approached significance for Stage IV ( p=0.272 for Stage III, and p=0.083 for Stage IV). For the six specimens observed in this study, more ADD were required to reach Stages III and IV for bodies that were placed during cooler months (January) compared to those placed during warmer months (June and September). The mean ADD to reach Stage III was for cool months and for warm months (p=0.01). The mean ADD to reach Stage IV was for cool months and for warm months (p=0.09). 67 (3), 2017 \ 383

6 Figure 1 Study specimens at Stage II, left to right, top to bottom: 04-01, 08-01, 10-01, 23-01, 30-01, Figure 2 Study specimens at Stage III, left to right, top to bottom: 04-01, 08-01, 10-01, 23-01, 30-01, Figure 3 Study specimens at Stage IV, left to right, top to bottom: 04-01, 08-01, 10-01, 23-01, 30-01, / 67 (3), 2017

7 Clothed Unclothed Specimen ADD to Reach Stage II ADD to Reach Stage III ADD to Reach Stage IV M M M M M M Average V V V V V W W W Average Table 3 ADD required for each specimen to reach Stages II, III, and IV. M represents specimens from the current study; V represents specimens from the Vass (1991) study; W represents specimens from the Watkins (1983) study. Figure 4 ADD to reach Stages II, III, and IV for each specimen. 67 (3), 2017 \ 385

8 Figure 5 ADD to reach Stages II, III, and IV, grouped by clothing. Discussion and Conclusion In the present study, clothing generally slowed the rate of decomposition as compared with unclothed specimens placed in the same environment. Although we did not calculate a model here for estimating PMI for clothed remains, this possible influence should be taken into consideration in forensic contexts where remains are found with clothing, especially because many studies documenting decomposition rates have been based on unclothed (typically pig) specimens. The relation between clothing and decomposition rate is challenging to assess because it is virtually impossible to completely isolate the effects of one factor among the many involved in decomposition rate. Moreover, many studies using human cadavers involve small sample sizes that make statistical analyses limited. However, the more data that are collected (especially using human cadavers), the better our understanding of the many factors that affect this medicolegally important process. The data from this study contribute to this important pool of data that are based on human samples and demonstrate one way in which data from well-documented studies can be combined into a more robust analysis. 386 / 67 (3), 2017

9 The fact that this was a partially retrospective study presents some potential issues and limitations. The two previous studies had different objectives and did not collect or record data using the same system as this study, requiring some interpretation of the descriptions provided by the previous authors. However, given the thorough documentation of observations and ADD provided in the previous studies, it is believed that the results and conclusions are reasonable on the basis of available data. Future studies should include a larger sample placed under more controlled experimental conditions. The differences in ADD required to reach each stage for cooler and warmer seasons among the six specimens observed in this study warrant further discussion. Several factors may be responsible for this. Firstly, perhaps the relation between ADD and decomposition is not as straightforward as previously thought; there may be a seasonal influence. Clothing may also have a greater effect on decomposition rate during different seasons. Because of possible seasonal variation, specimens from the clothed and unclothed studies were evaluated on the basis of whether they were placed during warmer months or cooler months. The differences, however, were not found to be significant. The differences may also be a function of the actual amount of clothing worn. Specimens placed during cooler months also had more clothing on. If this is the case, it would further support the conclusion that clothing slows the rate of decomposition and that more clothing may have an even greater effect. This could also suggest that variation in decomposition rate may be expected based on multiple layers of clothing, whether clothing or wrappings are tight or loose, and the composition or construction of the clothing or covering. Addition research on these variables may provide some clarity. Although additional research is needed, this pilot study supports conclusions of other reports [1, 6] that suggest clothing slows rather than accelerates the rate of decomposition. Moreover, the amount of clothing worn may also have an effect. Given the variation in clothing worn by forensic death investigation subjects, this information could help improve PMI estimates that are based on decomposition. Future research that directly compares the decomposition rate of clothed and unclothed remains is suggested. 67 (3), 2017 \ 387

10 Acknowledgment The authors wish to thank Murray Marks for his guidance on the study design and Tracy Betsinger for assistance with data collection. Disclaimer: The views expressed are those of the authors and do not necessarily reflect the official policy or position of the FBI. Names of commercial manufacturers are provided for identification purposes only, and inclusion does not imply endorsement of the manufacturer or its products or services by the FBI. For further information, please contact: References Angi M. Christensen 2501 Investigation Parkway Quantico, VA Gonzales, T. A.; Vance, M.; Helpern, M.; Umberger, C. J. Legal Medicine, Pathology, and Toxicology, 2nd ed.; Appleton-Century-Crofts Inc.: New York, Watkins, L. L. Late Postmortem Changes in Three Human Bodies in Knox County, Tennessee. Master s Thesis, University of Tennessee, Vass, A. A. Time Since Death Determinations of Human Cadavers Utilizing Soil Solution. Doctoral Dissertation, University of Tennessee, Vass, A. A.; Bass, W. M.; Wolt, J. D.; Foss, J. E.; Ammons, J. T. Time Since Death Determinations of Human Cadavers Using Soil Solution. J. For. Sci. 1992, 37 (5), Bass, W. M. Outdoor Decomposition Rates in Tennessee. In Forensic Taphonomy: The Postmortem Fate of Human Remains; Haglund, W. D., Sorg, M. H., Eds.; CRC Press: Boca Raton, FL, 1997; pp Mann, R. W.; Bass, W. M.; Meadows, L. Time Since Death and Decomposition of the Human Body: Variables and Observations in Case and Experimental Field Studies. J. For. Sci. 1990, 35 (1), Cahoon, S. E. Effects of Clothing on Human Decomposition and Deterioration of Associated Yarns. Master s Thesis, University of Tennessee, Goff, M. L. Problems in Estimation of Postmortem Interval Resulting from Wrapping of the Corpse: A Case Study from Hawaii. J. Agric. Entomol. 1992, 9 (4), / 67 (3), 2017

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