2.2. Air sampling of organic BPs Air sampling and concentration determination of organic BPs were per- formed according to two standards of industrial hygiene in China, respectively (GBZ159-2004 and GBZ/T192-2007). The sampling was conducted at pulverizing and packaging places at 1.5 m above the floor. Perchloroethylene filter (40 mm, Nantongjinnan Glassware Company, China) was loaded in the filter cassette of air sampler (ZC-Q, Zhejiang Hengda Instrument Company, China). The flow rate was at 25 l/min and the sampling time was 15 min. Six air samples were obtained at six different times in a work shift. The quartz contents of BPs samples were detected according to an occupational health standard of China (GBZ/T192.4-2007).