Three years ago, when Levi Strauss announced it had banned the use of sandblasting, labor 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 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 nonprofits, medical groups and labor organizations 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 UC Berkeley.

A Bangladeshi garment laborer works in a sandblasting factory in Dhaka on August 4, 2011.
A Bangladeshi garment laborer works in a sandblasting factory in Dhaka on August 4, 2011. ( MUNIR UZ ZAMAN/AFP/Getty Images)

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 utilize 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 look and feel of denim ... is noticeably different," she said.

The disconnect between what retailers say happens in the factories and what labor 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, coordinator of the Berkeley-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 organization 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 this summer. The organization 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.

Levi Strauss, a leading Bay Area retailer widely considered one of the most socially responsible brands, became the first U.S. apparel brand to announce a ban on sandblasting. The World Health Organization, U.S. Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health and California Department of Public Health have all warned about the health risks of sandblasting.

Workers can develop silicosis, an incurable disease that scars the lungs and can cause cancer, chronic pain, coughing, shortness of breath and heart failure. Gregory Härtl of the World Health Organization said silicosis is one of the oldest known occupational diseases, yet it still kills more than 8,800 workers worldwide each year.

There are other methods, including chemical sprays and washes, that give denim a distressed look. But industry experts say the alternatives tend to also be risky, more expensive and slower than sandblasting, and may eat away at a factory's razor-thin margins. Sandblasting can be done safely with protective gear -- the practice has been used for years in the U.S. for industrial purposes such as cleaning pipes and bridges -- but many garment workers wear only a rag around the mouth, sleep in the factories, and have no relief from the dust, Brown said.

None of the factories in China where sandblasting was discovered provided workers with adequate safety equipment, Muller said.

Safety inspections are often ineffective because workers are coached on what to say to auditors, and managers hide sandblasting equipment and in some cases set up fake factories, said Annabel Meurs of Fair Wear International, a nonprofit in the Netherlands that works with retailers to improve factory conditions.

"Most brands have no clue," Meurs said.

One of Levi Strauss' suppliers in China, Dongguan Golden City Washing, Sandblast and Brush Factory, continued sandblasting after the ban, with workers hiding the machines during audits. Levi Strauss discovered the covert operation in 2011 and cracked down on the factory; in January 2012 factory management "sent photos as proof" that the sandblasting equipment had been removed, a Levi spokeswoman said.

However, in October 2012, about nine months after Levi Strauss received the photos, workers disclosed to the Clean Clothes Campaign they were dismantling and hiding manual sandblasting machines from inspectors. Levi Strauss lists Dongguan Golden City as a current supplier.

Still, Levi Strauss' ban has helped, said Muller of the Clean Clothes Campaign. The company brought scrutiny to a practice that had continued mostly uninterrupted for nearly two decades. About 40 brands now have bans, adding pressure to factory managers to end unsafe labor practices.

But critics demand more -- they say clothing brands must stop designing the vintage styles that made sandblasting popular in the first place. Yet the style, which took off in the 1990s, is still hugely popular; Deede says faded jeans are in high demand at Target. And according to the Trend Council, which forecasts global style trends for retailers, the top denim looks for 2014 include faded and splattered styles -- the very look often created by sandblasting.

Contact Heather Somerville at 510-208-6413. Follow her at Twitter.com/heathersomervil.