Three years ago, when Levi Strauss & Co announced it had banned the use of sandblasting, labour advocates hoped the move by the top-selling jeans maker would help end the deadly practice, which gives denim a fashionable look but is linked to a fatal lung disease.
But even as the US company Target and Gap joined Levi Strauss in proclaiming bans, sandblasting persists in factories that make those retailers' clothes in China, India, Pakistan, Egypt and Bangladesh, countries responsible for the bulk of the five billion pairs of jeans made each year, research by nonprofit organisations, medical groups and labour organisations shows.
"There clearly is sandblasting going on. I don't know how anyone could really deny it," said Katie Quan, associate chair of the Labor Center at the University of California-Berkeley.
Counterfeit jean production, outsourcing in the supply chain, and vast factories that make jeans for dozens of brands under one roof make it difficult to track jeans from production to the shopping mall. But the groups say their research establishes that workers in many of these overseas factories are sandblasting - spraying sand on denim to make it appear bleached or distressed - without the necessary protective gear.
Levi Strauss says its suppliers have removed sandblasting equipment from their factories and that it regularly conducts on-site inspections at factories.
"No Levi Strauss & Co products utilise sandblasting in product development, design, finishing or in any other aspect of garment production," said a Levi Strauss spokeswoman who asked not to be named. "We do not request nor allow sandblasting at the supplier level."
Although Levi Strauss still sells bleached and distressed-looking jeans, the company says none of the styles requires sandblasting. And the company inspects all clothes before they reach stores to make sure that they haven't been sandblasted, according to the spokeswoman.
The disconnect between what retailers say happens in the factories and what labour groups report foreshadows immense challenges for other garment industry reform efforts, such as those now under way in Bangladesh following a factory collapse in April that killed more than 1,100 people.
The garment industry is built on a vast network of subcontractors hidden from regulatory oversight, experts say, so that even well-meaning fashion brands are unable to change the conditions in which their clothes are made.
"There is no such thing as a non-sweatshop in the global supply chain," said Garrett Brown, co-ordinator of California-based Maquiladora Health & Safety Support Network, a collection of occupational health and safety professionals who educate factory workers about workplace hazards.
"Retailers have almost no ability to know where it's being done, by whom it's being done and with what technology, and as a consequence, they have no idea the terrible stuff that's going on."
The Clean Clothes Campaign, an international organisation advocating for garment workers, recently interviewed workers in six factories in an industrial region of China that produces about half the world's jeans, and laid out the findings in a report. The organisation found that five of the factories - employing a combined 8,000 workers - still use sandblasting. The largest one makes clothes for Levi Strauss, Gap and its sister brand Old Navy. Gap said it banned sandblasting in 2011.
Sandblasting was also discovered at a factory with 300 workers that makes clothes for Levi Strauss. And two factories make jeans for Wrangler, a brand sold at Target, which banned sandblasting last year.
Of the six factories, only one - also a Levi Strauss supplier - had eliminated sandblasting because it "has essentially outsourced these processes" to another factory, according to the report.
"The impact of the ban has been patchy, poorly monitored and widely circumvented," said Dominique Muller of the Clean Clothes Campaign.
"We discovered that regardless of whether a brand has banned sandblasting or not, manual sandblasting still takes place, often at night to avoid detection by audits."
Target spokeswoman Jessica Deede said the retailer regularly audits factories it works with and if it finds sandblasting, Target may cut ties with those factories for at least three years.
"We clearly communicate our sandblasting ban with national brand partners, such as Wrangler," Deede said.