The explosion in a Kunshan auto parts factory, along with a string of similar cases in China, revealed safety loopholes in some high-risk sectors, as well as gaps in the protection of workers' rights and occupational safety.

"Chinese workers' lives and health have been compromised too much for the sake of being the world's factory," said Dai Chun, a labor expert from the Hunan Federation of Trade Unions.

At the Kunshan Zhongrong Metal Products Co, attendance records show that workers pulled shifts of more than 14 hours a day. About 260 were working when the massive blast occurred at 7:37 on Saturday morning