Originally published on June 1, 2019.

Legislators in Washington state just signed a new bill into law making it legal for people to compost their bodies upon death rather than choosing a more traditional funerary practice such as burial or cremation.

Advocates of the procedure suggest it could be a more environmentally benign way to dispose of human remains.

The driving force behind the human composting movement in the U.S. is Katrina Spade. She founded a company called Recompose to develop the idea.

Spade said in a TED Talk the inspiration to develop the idea of human composting came when she got a call from a friend.

"She was like, 'Hey, have you heard about the farmers who are composting whole cows?' And I was like, 'Hmm…,'" Spade said. "[It] turns out that farmers and agricultural institutions have been practising something called livestock mortality composting for decades."

This is a procedure used to dispose of the carcasses of animals that have died and can't be sold for human consumption.

Spade then turned to Lynne Carpenter-Boggs, professor of soil science and sustainable agriculture at Washington State University in Pullman, Wash. Carpenter-Boggs had been studying livestock mortality composting for about 20 years.

It was a very fine compost that was relatively stable, [and] it smelled good. - Lynne Carpenter-Boggs, Washington State University

"I had seen what this process is capable of doing with whole cows and horses," said Carpenter-Boggs — now also the scientific advisor for Recompose — in conversation with Quirks & Quarks host Bob McDonald. "Anyone who's done this and seen how effective it can be has kind of had the inkling that this could have wider use."

Carpenter-Boggs and her team conducted a pilot study with six human cadavers to test the conditions that would be required to turn a dead body into soil in a timely manner. They're calling this process for humans "natural organic reduction."

How this works with animals

To compost a whole farm animal, the body is placed within layers of organic materials like hay, silage and even manure. Microbes present in the organic material release enzymes that break down organic materials like muscle and fat. The process produces heat, which accelerates the microbial action.

"In composting, it is quite different than other types of decomposition in that you need enough material and the right combination of materials that you are promoting extremely high levels of microbial activity," said Carpenter-Boggs.

This soil can then be used to grow new life. Eventually you could be a lemon tree. - Katrina Spade, Recompose

Within a few months, the microorganisms turn the dead animal and the organic material that was added to it into pathogen-free, fertile compost.

The process for humans

Spade said in her TED Talk that she imagines the process could be part of a ritual that would give back to the earth.

"When someone dies, their body is taken to a human composting facility," she said. "After wrapping the deceased in a simple shroud, friends and family carry the body to the top of the core which contains the natural decomposition system"

Carpenter-Boggs said, compared to what they do for livestock, the procedure for composting human remains would have to be modified in order to speed the process up and reduce the cost.

It would be done in a contained vessel which would give them more control of the process. The vessel would be rotated to provide physical disruption so oxygen could access all parts of the composting material. This would also help control the moisture level.

What organic material they would add to the vessel to facilitate composting would depend on what's locally available.

"Some things that have been used in our trials, and in other material composting, would be things like wood chips, hay, grains — really any type of organic materials can be used," she said.

Katrina Spade, upper left, the founder and CEO of Recompose, a company that hopes to use composting as an alternative to burying or cremating human remains, looks on Tuesday, May 21, 2019, as Washington Gov. Jay Inslee, centre, signs a bill into law at the Capitol in Olympia, Wash., that allows licensed facilities to offer "natural organic reduction," which turns a body into soil in a span of several weeks. (Ted S. Warren/AP Photo)

Quality of compost from humans

Carpenter-Boggs said she was very pleased with the quality of compost that came out of her human cadaver studies.

"By the time we completed our trials, we were developing material that was very pleasant to handle, it was a very fine compost that was relatively stable, [and] it smelled good," she said.

One of the questions is how the compost might be used. "This soil can then be used to grow new life. Eventually you could be a lemon tree," Spade said in her TED Talk.

Carpenter-Boggs said that they were looking into using it in conservation areas or memorial gardens.

Regulators in Washington state are now sorting out the finer details of how this will work, but Recompose hopes this will be a service people will be able to access by late 2020.

Spade said this will just be the beginning: "Our Seattle facility will function as a model for these places all over the world. We've heard from communities in South Africa, Australia, the U.K., Canada and beyond."

In Canada, there are services offering green burials where bodies are not embalmed, but are instead buried in a simple shroud or wooden box. Depending on the burial environment, however, parts of the body may never decompose.

In two provinces — Ontario and Quebec — people can opt for a service called alkaline hydrolysis, which dissolves the soft tissues of the body leaving only bone and teeth.