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You probably know that composting banana peels and eggshells can help reduce your negative impact on the environment. But did you know that, once you die, you can do that with your body, too?

Human composting — also known as natural organic reduction or the reduction of human remains — is the practice of placing a dead body in a reusable vessel with biodegradable materials that foster the transformation into nutrient-dense soil that can be returned to loved ones or donated to conservation land.

The notion of going green even in death might sound far-fetched, but California has become the latest state to sign a human composting bill into law, set to go into effect in 2027. Washington became the first state to legalize human composting in 2019, followed by Oregon, Colorado and Vermont.

Advocates of human composting hope it can help slow the climate crisis driven by burning fossil fuels that produce planet-warming greenhouse gas emissions such as carbon dioxide and methane. Cremations require lots of fuel — cremating one corpse emits an estimated 418 pounds of carbon dioxide into the air, the equivalent of driving 470 miles in a car, according to Chemical & Engineering News, a publication of the American Chemical Society. In the United States, cremations account for 1.74 billion pounds of carbon dioxide emissions each year, according to Green Burial Council Inc., an organization that oversees certification standards for cemeteries, funeral homes and product providers engaged in sustainable burial practices.

“Human composting … uses much less energy than cremation, which uses fossil gas to create heat of over 1,400 degrees Fahrenheit,” said Katrina Spade, founder and CEO of Recompose, a licensed green funeral home in Seattle. “When human composting transforms the organic material of our bodies, carbon is also sequestered in the soil created. Rather than being released as carbon dioxide gas through exhaust during a cremation, the carbon matter contained in each body returns to the earth.”

Cristina Garcia, the California Assembly member who introduced the state legislation, said wildfires and extreme drought are reminders that climate change is real, and that methane and carbon dioxide emissions must be reduced. “For each individual who chooses (natural organic reduction) over conventional burial or cremation, the process saves the equivalent of one metric ton of carbon from entering the environment,” Garcia said in a September news release.

Recompose, Spade’s company, became the first human composting facility in the US when it opened in December 2020. Spade thought of human composting in graduate school after learning about livestock mortality composting, when farm animals are recycled back to the land, she said.

Human composting happens in steel cylinders known as vessels at Recompose.

The industry is new, and there is little research on how much better human composting is for the environment compared with traditional burials, cremation or green burials. And the process isn’t carbon-free since it still involves machinery operated by electricity and transportation of bodies, materials and remains, said Ed Bixby, president of the Green Burial Council.

As interest in more sustainable end-of-life options grows, transparency about the practice is crucial, Bixby said. A recent National Funeral Directors Association survey that found 60.5% of respondents were interested in exploring “green” funeral options because of potential environmental benefits, cost savings or other reasons.

“With our families, we never want them to be disturbed or upset believing something that isn’t,” Bixby said. “If you’re going to do something, if it’s environmentally conscious, we think that’s wonderful. But we want to be sure that people understand what they’re buying into.”

Reducing death’s environmental and financial impact

At Recompose, human composting happens in a steel cylinder that’s 8 feet long and 4 feet tall, Spade said. A body is placed in the vessel on a bed of wood chips, alfalfa and straw.

“Human composting creates an environment in which beneficial microbes thrive, with a specific moisture content and ratio of carbon and nitrogen materials,” Spade said.

Over the next 30 days, everything inside naturally decomposes. One body creates a cubic yard of soil amendment — a substance added to soil to improve its texture or health — which is removed from the vessel and cured for two to six weeks. Afterward, it can be donated to conservation projects, or a certain amount can be returned to loved ones. But the amount loved ones receive can depend on what a state allows since the soil would still be legally considered human remains with regulations on what people can do with them, Bixby said.

The practice also avoids the introduction of nonbiodegradable materials — such as concrete or plastic vaults, steel caskets or lacquers — to the atmosphere or land, and forest depletion for wood caskets, Bixby said. Human composting would also protect funeral home workers from exposure to high levels of formaldehyde, which has been found to cause myeloid leukemia and rare cancers.

Human composting could lower the financial footprint of end-of-life arrangements, too. The median cost of a funeral with cremation in the US in 2021 was $6,971, and the median cost of a funeral with a viewing and burial was $7,848, according to the National Funeral Directors Association. But the median burial estimate doesn’t include a plot, headstone or other cemetery costs associated with a traditional burial, which can often double the cost, Spade said.

“Recompose strives to keep the price for human composting comparable to other death care options,” Spade said.

Who’s a candidate for composting?

Recompose has composted more than 200 corpses into soil since opening nearly two years ago and has more than 1,100 people signed up for Precompose, the company’s prearrangement program, Spade said.

“We hear from our clients that knowing that their body — or that of their loved one — will be able to return to the earth is deeply comforting,” Spade said.

Not everyone is eligible for human composting. Natural organic reduction destroys most harmful pathogens, but there are three rare diseases that disqualify a body from undergoing human composting, Spade said: Ebola, tuberculosis and diseases caused by prions, which are abnormal, transmissible pathogenic agents that can cause abnormal folding of certain brain proteins.

The list of states allowing human composting may soon grow longer. A bill in New York state has passed both legislative houses and is on its way to the governor’s desk, Spade said. And in Massachusetts, state Reps. Jack Lewis and Natalie Higgins are leading a bill to legalize human composting there.

Most funeral homes, however, might not be quick to adopt the practice, Bixby said. Once a permit is issued, direct cremation can be done the same day, he added. A burial typically takes three to five days, while human composting can take up to 120.

“The problem I see, as far as this growing, is that you can’t do high volume,” Bixby said. “As long as this process is, having five or six (vessels) doesn’t do a lot of good. … As a businessman, my feeling is this really won’t gain much ground for that main reason.”

He added, “It doesn’t make a lot of practical sense. And I hate to make things about money because it shouldn’t be, but at the end of the day, when you’re providing a service, it has to be about the income because you have to keep the lights on.”