Quantification of adipocere degradation with and without access to oxygen and to the living soil

Adipocere is formed from body fat in moist and oxygen-deficient decay conditions. The persistence of adipocere may cause problems for the reuse of graves after the expiration of statutory resting times in some countries. Up to now, no quantitative data existed on the persistence of adipocere in either aerated or anoxic conditions. We investigated the rate of degradation (disappearance) of adipocere in five different samples from human corpses. The experimental incubation was (a) in water without air contact, (b) in water with access to air, (c) in physiological saline with access to air, (d) on sterilized quartz sand, (e) in vitro on living soil, and (f) buried 15 cm deep in field soil. The weight loss of the samples was determined after 215 (293) days and half-lives were calculated under the assumption of simple first-order kinetics. Furthermore, the nitrogen content and the fatty acid composition of the adipocere samples were analyzed. The results revealed half-lives that differ between the adipocere samples from 11 to 82 years under anaerobic conditions (mean of all samples, 37 years). In air, the half-life of adipocere was reduced to about one tenth, ranging from 0.7 to 10 years (mean of 2.8 years for all samples incubated in aerated physiological saline, mean of 4.0 years for all samples incubated on living soil in the laboratory). Burying adipocere in a biologically active field soil resulted in half-lives of disappearance from 1.2 years to 2.1 years (mean, 1.5 years). The N content of the adipocere samples ranged between 1.9 and 6.7 mg N g(-1). The sample with the highest N content was also that with the lowest half-life of disappearance in all types of incubation. The fatty acid analysis of the samples revealed a composition typical of adipocere, with a clear dominance of saturated acids (palmitic, myristic and stearic acid) over unsaturated ones. The variation of fatty acid composition between the different adipocere samples could only be attributed partly to their age and the burial conditions. It can be concluded that the aeration of adipocere-laden corpses will lead to a disappearance of adipocere (and hence restitution of the decay process) within a time span of several years.