Stand.earth and the National Resources Defense Council just released a report describing the “tree-to-toilet” pipeline, concluding that “[t]he consequences for Indigenous Peoples, treasured wildlife, and the global climate are devastating.”

The U.S. consumes more toilet paper than any other country, almost three rolls per person each week. And the brands they choose to use aren’t sustainable, with hardwood trees being pulped to create the soft toilet paper consumers want. Following the United States’ annual use of 141 rolls of toilet paper per capita is Germany with 134 rolls and the United Kingdom with 127. Japanese consumers average 91 rolls annually, while the Chinese average just 49.

Estimating the U.S. tissue market to be worth $31 billion, the report took the three biggest paper product producers in the U.S. to task: Procter & Gamble (PG), Georgia-Pacific and Kimberly-Clark (KMB) use no recycled content in their consumer toilet paper, they say.

A Kimberly-Clark spokesperson told Fortune that it is committed to making products that provide health and hygiene benefits while “ensuring the resilience of the forests where we sustainably source our fiber.” It will remain engaged in “an ongoing dialogue” with the NRDC on “the complex challenges presented in their report” and will continue to demonstrate “how Kimberly-Clark is working to be a part of the solution.”

A Georgia-Pacific spokesperson said the company is in fact a large recycler, using more than 2 million tons of recycled paper annually in a variety of products. “Sustainably harvested virgin wood provides attributes including softness and absorbency while recycled towel and tissue products provide a beneficial reuse for recovered paper,” the spokesperson said, and the company is committed to sustainable forestry practices.

In the report’s sustainability rankings, eco-friendly brands such as Seventh Generation and basic options from Whole Foods and Trader Joes earned an A. But Cottonelle, Scott, Charmin, Ultra Soft, Angel Soft and Quilted Northern earned grades of D or F. Paper towel brands Viva, Brawny and Bounty also got grades of D or F.

“We’re calling on Procter & Gamble, as the maker of America’s leading toilet paper brand, to stop flushing forests down the toilet,” report co-author Shelley Vinyard said in a statement. “Procter & Gamble has the innovation resources to bring Charmin into the 21st century; the question is whether the company will embrace its reputation as an innovator to create sustainable products using recycled material instead of clear-cut trees.”

A spokesman for P&G stressed the company’s commitment to sustainability, saying 100% of its wood fiber comes from responsibly managed forests, certified by third parties such as the Forest Stewardship Council. “Virgin fiber in tissue products is preferred by consumers, and ‘does the job’ much more efficiently,” the Procter & Gamble spokesman told Fortune. “By using virgin fiber from responsibly managed forests, our products are more absorbent, so consumers can do more with less waste. Paper products made from recycled materials are less soft, less absorbent and lack the strength that products manufactured from virgin fibers can provide.”

Industrial logging claims more than a million acres of northern forests every year, equivalent to seven hockey rinks each minute, in part to meet demand for tissue products in the United States. The paper and printing industries, meanwhile, argue that Canada’s forest area of 857 million acres has remained stable over the past 25 years, per Two Sides.

“Canada has among the most rigorous frameworks for forest management in the world that includes science-based considerations for wildlife and forest ecosystems. As a result, Canada has retained over 90% of its original forest cover and has almost zero deforestation (0.01). In fact, Canada plants over 615 million trees annually or 1,000 trees every minute,” said industry group Forest Products Association of Canada in a statement. “It is concerning that NRDC suggests alternative wood fiber sources that are more carbon intensive or sourced from countries with much lower forest management, labour and human rights standards.”

The price of hardwood pulp, used in toilet paper and tissues, has risen dramatically over the past few years, which has in turn increased consumer prices for tissue. But manufacturers have been slow to integrate recycled paper into their products, as consumers prefer the soft feel of virgin pulp.

The report from Stand.earth and the NRDC recommends consumers first and foremost reduce their toilet paper use, but also that manufacturers increase the use of recycled paper and alternative fibers in toilet tissue.

This story has been updated to reflect statements from Georgia Pacific, Kimberly-Clark, Procter & Gamble, and the Forest Products Association of Canada.