Adipocere decomposition

Grave wax" is a term for a crumbly, waxy substance called adipocere. Adipocere starts to form on the human body about a month after it is buried. It forms easily on the fatty parts of the body such as the cheeks, abdomen, and buttocks. The waxy adipocere protects the body from further decomposition and has even been found on 10O-year-old exhumed corpses. This buildup occurs when a body is buried in highly basic (alkaline) soil. The waxy substance is produced by a chemical reaction between the basic soil and fats in the body in a process called saponification. Saponification is also the process used in the manufacture of soap. 

Fiedler, S. and Craw, M. (2003). Decomposition of buried corpses, with special reference to the formation of adipocere. Naturwissenschaften 90,291-300. 

In an initial study at the pasture site, replicate samples of dyed polyester, undyed wool, undyed cotton, and synthetic indigo-dyed denim were placed above (30 cm depth) and below (60 cm depth) cadavers and at 30 cm and 60 cm depth in control graves. When exhumed at 24 months, cadaver B was still actively decomposing with extensive adipocere formation at the base of the grave. This was confirmed by determination of carbon dioxide respiration rates for soil samples taken at the time of recovery (Wilson 2002). It was clear that decomposition of the cadaver had influenced the decomposition rates of the textiles depending on location in the grave after 24 months of burial (Table 7.6). 

Plastic coverings are often used to wrap the body before burial, both within a coffin or when placed directly in the soil. The use of plastic to cover bodies also greatly retards decomposition however, its affect on adipocere formation is variable. Some cases report extensive adipocere formation in bodies wrapped only in plastic (Manhein 1997), whereas experimental studies show that tissue wrapped in plastic and buried in soil will result in a semifluid mass of putrefied tissue but no adipocere formation unless clothing is also present (Forbes et al. 2005b). 

The formation of adipocere can occur in a vast range of burial environments and will proceed by the extraction of moisture from the internal tissues until they become desiccated and mummified (Ubelaker 1995). The dehydration of the internal organs as a result of adipocere formation accounts for the cessation of putrefaction and subsequently decomposition (Fiedler, Sch-nekenberger, and Graw 2004). In this way, adipocere formation can preserve human remains to an extent that can permit postmortem identification of the body (Poison et al. 1985). Frequently, adipocere formation and mummification will occur simultaneously, making the corpse extremely resistant to decomposition (Bereuter et al. 1996 Makristathis et al. 2002) (Figure 8.2). 

However, adipocere formation is not an end product, and eventually adipocere will also decompose. The factors necessary for decomposition of adipocere are not well documented. Similar to its formation, the decomposition of adipocere appears to be dependent on the surrounding burial environment (Fiedler et al. 2004). Early studies reported that an aerobic environment was necessary to decay adipocere, suggesting that adipocere would only decompose when a grave site was exposed to air or when an adipocerous body was exhumed to the soil surface (Evans 1963 Mant 1957, 1987). More recent studies suggest that the persistence of adipocere in a burial environment is related to the exclusion of gram positive bacteria, including species of Bacillus, Cellulomonas, and Nocardia, which are able to decompose adipocere (Pfeiffer et al. 1998). 

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