An explosion on December 17 at an Apple (AAPL.Nasdaq) supplier in Shanghai triggered by aluminum dust created during the polishing of iPad caused 61 injuries, Bloomberg reported, citing China Labor Watch. The incident occurred at Pegatron (4938.TPE)’s Ri Teng Computer Accessory factory in Songjiang district in Shanghai, and the cause was similar to that of a Foxconn (2354.TPE) factory accident in May, according to a statement from China Labor Watch. Three workers died and 15 were injured on May 20 at the Chengdu factory of Foxconn, Apple’s largest contract manufacturer, an incident which the firm blamed on “combustible dust.” “We are working closely with Pegatron to understand the cause of this accident, said Apple’s spokeswoman Carolyn Wu. Shanghai Songjiang local authorities have begun investigating the accident at Ri Teng Computer Accessory.