Blood lead levels of children and its trend in China. 
To evaluate Chinese children's blood lead levels (BLLs) and identify its distribution features, we collected articles on children's BLLs published from Jan, 2004 to Aug, 2007 with sampling time since 2001, by searching Chinese Biomedical Disk (CBMDisk), Chinese Journal Full-test Database (CJFD) and other ways.  After a rigorous investigation, 35 articles eligible for inclusion criteria were reviewed.  Meanwhile, to reveal the trend of Chinese children's BLLs, the data was compared with the results from our former study carried out in 2004, which reviewed the articles published since 1995 to 2003.  The results showed that the mean BLLs of Chinese children from 2001 to 2007 was 80.7 microg/L (45.5-165.3 microg/L), and 23.9% (3.2%-80.7%) of children's BLLs was higher than 100 microg/L. Both BLLs and prevalence of BLLs higher than 100 microg/L were lower than that of 1995 to 2003.  Of 24 provinces or cities, only 4 showed higher BLLs and higher prevalence rates of lead poisoning (BLLs > or =100 microg/L) than that of 1995 to 2003.  The mean BLLs of children living in industrial areas were higher than those in urban and suburban areas, and suburban higher than urban areas.  Boys' BLLs were 79.3 microg/L, significantly higher than girls 76.9 microg/L (P<0.001).  The results also showed that children's BLLs increased with their ages, and the decreased BLLs for all age were observed comparing with the results of our former study in 2004.  Overall, our study revealed that the BLLs of children in China showed a decreasing trend after gasoline with lead was banned in China in 1st July 2000.  Our study also showed that the BLLs of children in China were still higher than that in developed countries, which suggested that children's lead poisoning prevention and controlling would be a long-term mission in China.