Tissue digestion is a process which can be used to dispose of human and animal remains. It involves essentially dissolving the remains, reducing them to about two percent of the original body weight, depending on the size of the original specimen. Research laboratories have been using tissue digestion since the 1990s, when the technique was first developed, and in the early 2000s, mortuaries demonstrated a growing interest in making the technology available to their clients.
The technical term for tissue digestion is “alkaline hydrolysis,” with the funeral industry preferring the more friendly-sounding “water reduction.” When remains are subjected to tissue digestion, they are placed in a heated and pressurized container and exposed to lye, which dissolves much of the organic material, leaving behind a thick brown liquid and some of the larger bones.
The brown liquid produced by alkaline hydrolysis is perfectly sterile, and could potentially be flushed down a drain. In fact, most facilities do just that. The remaining bones are dry and crumbly, and they can be pulverized and stored or otherwise disposed of, depending on how one feels about the decedent.
There are a number of advantages to tissue digestion when compared to other techniques for handling remains. It is significantly less expensive than cremation, and it is also much more environmentally friendly. From the point of view of laboratories and researchers, alkaline hydrolysis is the preferred method of disposal since it is easy and efficient, and in addition the process destroys prions, ensuring that the reduced remains are safe to handle. Medical schools and other facilities which perform research on donated cadavers also use tissue digestion to handle their remains.
For humans, tissue digestion appeals to the alternative burial community, which likes the idea that the process is both cheaper and more environmentally friendly than cremation. Some people feel that alkaline hydrolysis is disrespectful to human remains, since it does involve turning the remains into brown goo, but others argue that all remains eventually decay: tissue digestion simply speeds the process. Critics also object to the idea of pouring human remains down a drain, although closed reclamation systems could potentially be used to reduce the liquid to a powder which could be kept with the pulverized bones.
Several companies manufacture tissue digestors of various sizes, ranging from extremely large models which are designed to handle livestock to smaller versions for small animal hospitals. Tissue digestors which are specifically designed to handle human remains are also available; as of 2008, no funeral home officially offers alkaline hydrolysis to its clients, but there are hopes that the process may be open to the public soon.