Metal/metalloid levels in hair of Shenzhen residents and the associated influencing factors

129 Shenzhen residents' hair samples were collected and the metal/metalloid concentrations of Hg, As, Pb, Cd, Cr, Cu, Mn, Zn, Fe and Ni were detected. Meanwhile, the relationships between metal/metalloid contents in human hair and gender, age, seafood diet habit, smoking habit, as well as the housing type (dwelling environment) were analyzed. Results showed that the average content of Hg, As, Pb, Cd, Cr, Cu, Mn, Zn, Fe and Ni in human hair of Shenzhen residents was 0.76 +/- 0.96, 0.10 +/- 0.04, 5.25 +/- 4.88, 0.25 +/- 0.33, 0.60 +/- 0.31, 13.84 +/- 3.67, 2.82 +/- 2.01, 196.90 +/- 145.01, 12.20 +/- 5.10 and 0.34 +/- 0.32 mu g/g, respectively. Compared with other regions at home and abroad, most metal/metalloids in Shenzhen residents were at a moderate level, and the highly toxic elements (i.e. Pb, Cd, As and Hg) didn't exceed the upper limit of normal values in China. Statistical analysis showed that the young male people contained significantly higher (p < 0.05) level of Pb (in age group of 20-30 years old) and Fe (in age group of 20-40 years old) in hair than the female people. Smokers had significantly (p < 0.05) higher level of Cd (0.35 mu g/g) but lower level of Zn (101.24 mu g/g) than non-smokers (Cd: 0.17 mu g/g; Zn: 252.63 mu g/g). Hg and Pb contents in hair of Shenzhen people were positively related with the frequencies of seafood consumption and the age, respectively. Moreover, residents lived in private buildings (well decorated house) accumulated significantly higher (p < 0.05) levels of Pb, Cr, Fe and Ni as compared with those lived in public rental house and village house (no decoration or simple decoration), suggesting that decoration material was also an important way for human exposure to heavy metals.