Turning human bodies into compost works, a small trial suggests

Breaking down bodies into dirt may be an environmentally friendly alternative to burial or cremation

Person holding sample of composted cow

Katrina Spade of Recompose, a human remains composting company in Seattle, holds compost derived from a cow (bag on left) and material used in the process such as straw, wood chips and alfalfa (bag on right). In 2019, Washington became the first state in the United States to legalize human composting.

Elaine Thompson/AP Photo

SEATTLE — Human bodies make great worm food. That’s the conclusion of pilot experiments with six dead bodies that were allowed to decompose among wood chips and other organic material.

The results, presented February 16 at the annual meeting of the American Association for the Advancement of Science, suggest that composting, also called natural organic reduction, is a way to handle dead bodies that’s easy on the Earth.

Disposing of dead human bodies can be a real environmental problem. Embalming relies on large quantities of toxic fluid, and cremation throws off lots of carbon dioxide. But composting, in which microbes break down the bodies into soil, “is a fabulous option,” says Jennifer DeBruyn, an environmental microbiologist at the University of Tennessee in Knoxville who wasn’t involved in the study.

In 2019, Washington became the first state to legalize natural organic reduction as a post-life option. A Seattle-based company called Recompose expects to start accepting bodies for composting soon.

In a news briefing, soil scientist Lynne Carpenter-Boggs of Washington State University in Pullman described a pilot experiment in which six bodies were put into vessels that contained plant material and routinely rotated to provide optimal conditions for decomposition. About four to seven weeks later, microbes in the material reduced the bodies to skeletons.

Each body resulted 1.5 to 2 cubic yards of soil-like material containing bones. Commercial processes would likely use more thorough methods to process the bones, said Carpenter-Boggs, who is a research adviser to Recompose. Her analyses also have shown that the resulting soil meets safety standards set by the U.S. Environmental Protection Agency for such contaminants as heavy metals.

Animal carcasses have long been turned into rich soil in similar ways, DeBruyn says. “The idea of applying it to humans, to me, as an ecologist and someone who has worked in composting, it just makes perfect sense, honestly.” The heat produced by busy microbes has the added benefit of killing off dangerous pathogens. “Automatic sterilization,” DeBruyn calls it. Once when composting cattle, “the pile got so hot that our temperature probes were reading off the charts, and the wood chips were actually scorched,” DeBruyn says. 

One thing not killed by high heat is prions, extremely durable misfolded proteins that can cause disease (SN: 9/9/15). That means that composting “wouldn’t be allowed for people who have diagnosed Creutzfeldt-Jakob disease,” Carpenter-Boggs said.

It remains to be seen how widely adopted the process of composting human bodies becomes. Lawmakers in other states are considering the method, Carpenter-Boggs said.

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