LONDON - Three brands of toilet paper advertised as being made of bamboo mostly contained hardwood, according to tests conducted by a British-based consumer protection non-profit.

The analysis, carried out in November by Which?, found that toilet paper from Bumboo and Bazoo, which promised to be “100 per cent bamboo”, contained only 2.7 per cent and 26.1 per cent of bamboo respectively. Naked Sprout, another bamboo toilet paper brand, had 4 per cent bamboo.

The toilet paper that was tested was made of mostly fast-growing virgin hardwoods, largely eucalyptus, with some acacia in Bazoo and Bumboo. Two other products, from the companies Who Gives a Crap and The Cheeky Panda, were found to contain 100 per cent bamboo.

Bamboo has been hailed as a miracle material for decarbonisation because it is fast-growing, durable and suitable for use in many materials and products, from clothing to furniture. But the new tests shed light on the difficulty of ensuring that products advertised as eco-friendly are accurately labelled, and supply chains are tracked and monitored.

“Businesses must take responsibility for ensuring their products contain what they say on the packaging so that shoppers who want to make sustainable choices can trust the information they are given,” said Ms Emily Seymour, sustainability editor at Which?.

All three companies said their supply chains were certified by the Forest Stewardship Council (FSC), a non-profit that awards labels to products that have passed certain standards of sourcing. A spokesperson for the council said it was “concerned” by the findings and was investigating.

The tests were carried out at an independent lab using internationally recognised methods created by the Technical Association of the Pulp and Paper Industry, according to Which?.

Bumboo co-founder Rob Ingram said the issues related to a specific batch of toilet paper and were linked to a storage unit that was part of its supply chain in China. “As this is a shared facility, it would have impacted other companies,” he added. The company now tests every batch and publishes the results on its website, he said.

Bazoo’s founders Tom Trow and Sanmarie Grobler said they were in “extensive communications” with FSC to “understand clearly where this error occurred”, given their toilet paper is “vigorously audited” by the non-profit. “We were incredibly disappointed to know that any of our rolls had been contaminated at source,” they said in an e-mail.

A spokesperson for Naked Sprout said it was “incredibly disappointed” by the findings and said the tests had “limitations”. The company said the FSC told it “there have been no issues identified with any of our pulp suppliers”. BLOOMBERG