OBJECTIVETo explore the exposure level and risk factors of heavy metal among Shanghai infants in their prenatal period.

METHODSA total of 1652 pregnant or puerperal women were recruited from 10 midwifery-qualified hospitals in Shanghai since October 2008 to October 2009, by the stratified cluster sampling method. They answered the questionnaire and their umbilical cord blood and serum were collected to detect the content of Pb, Hg, Mn, Cd, As and Tl. The risk factors were analyzed by single and multiple regression methods respectively.

RESULTSThe median value of the content of Pb, Hg, Mn, Cd, As and Tl were 41.00, 1.88, 4.10, 0.03, 0.86 and 0.02 µg/L respectively. The Hg concentration of pregnant women who ate fish for 4 - 7 times per week (9.7% (160/1652)) was 2.76 µg/L, which was higher than that of pregnant women who only ate fish for 1-3 times per week (49.3% (814/1652)) and those who seldom ate fish (40.0% (661/1652)); the Hg concentration in the two groups above were 2.41 and 2.03 µg/L separately. The difference had statistical significance (χ(2) = 36.40, P < 0.001). Meanwhile, the concentrations of Pb and Tl in the group of pregnant women whose houses were remodeled by PVC pipe (85.0% (1404/1652)) was higher than the concentrations in group of pregnant women whose houses were remodeled by galvanized pipe (15.0% (248/1652)); the Pb concentration in the two groups above were 45.54 and 40.00 µg/L (Z = 2.54, P < 0.05) and the Tl concentration in the two groups above were 0.021 and 0.018 µg/L (Z = 2.97, P < 0.05). However, the As concentration in the group of PVC pipe remodeled was 4.33 µg/L, which was lower than that in the group of galvanized pipe (9.37 µg/L). The difference had statistical significance (Z = 3.99, P < 0.01). The concentrations of Mn, Cd and Tl in the groups of pregnant women whose house had been remodeled in the last 3 years (38.0% (628/1652)) were 14.78, 0.51 and 0.022 µg/L separately, which were all significantly higher than those in the groups of women whose houses' were not remodeled (62.0% (1024/1652)), whose concentrations were 11.01, 0.29 and 0.02 µg/L respectively. The differences had statistical significance (Mn: Z = 2.46, P < 0.05; Cd: Z = 2.38, P < 0.05; Tl: Z = 2.81, P < 0.01).

CONCLUSIONThe infants in Shanghai were exposed to heavy metals in their prenatal period. The main sources of the exposure were daily diet and remodeled pollution.