The labor practices of Apple's Chinese suppliers are increasingly under scrutiny. Workers are seen inside a Foxconn factory in the township of Longhua in the southern Guangdong province, May 26, 2010. Reuters/Bobby Yip

For millions of consumers, the Apple iPhone 6 is synonymous with convenience and comfort. Life at a Chinese factory that churns out the smartphone units is an entirely different matter.

Workers at a major Apple supplier in Shanghai often toil in excess of the tech giant’s self-imposed 60-hour limit per week, putting in 12-hour shifts six days a week. They earn the Chinese minimum of less than $2 an hour before overtime and share crowded, lugubrious dormitories -- spaces where mold thrives, working toilets are rare and bedbugs common. Relying on research from an undercover worker, the findings were released Thursday in a report from China Labor Watch, a nonprofit in New York City, and Future in Our Hands, a Norwegian environmental group.

Apple did not respond to a request for comment.

The research cited a number of other unsafe and apparently illegal labor practices at the Shanghai factory, which is operated by the Taiwanese electronics company Pegatron.

According to the report, the undercover worker was never informed of emergency exits and never participated in an emergency drill. Pegatron employees are forced to sign forms that certify they’ve undergone at least 20 hours of pre-job safety training -- Chinese law requires 24 hours -- but the undercover investigator received only eight hours. Meanwhile, workers are informed that iPhone 6s production involves a number of toxic chemicals -- including cadmium, mercury and arsenic -- but they are not told when and where the substances are present in the production process or how they should protect themselves.

Chinese law mandates employers contribute to health insurance, but factory workers cannot verify Pegatron pays its share into the system, according to the report. The company does not provide mandatory contributions to workers’ housing funds. Researchers also said the long workweeks violate the nation’s overtime laws, which prohibit no more than 36 hours of overtime a month. Even Apple’s self-imposed limit of 60 hours a week, which the report says is regularly ignored, equates to about 85 hours of overtime a month -- well above the legal maximum.

China Labor Watch published a study that documented many of the same problems at the factory in 2013. Many of the issues identified two years ago, it said, “have not seen meaningful change.”

Pegatron assembles about a quarter of iPhones, according to Nomura Holdings. During the busy season, according to China Labor Watch, the Shanghai factory employs 100,000 people.

The labor practices of Apple’s suppliers in China came under intense scrutiny in 2010, when more than a dozen workers at a Foxconn factory in Shenzhen committed suicide.