Study on hair trace elements levels of pregnant women from birth defects surveillance system

  Objective   To explore early pregnant women's hair trace elements distribution status between high and low birth defects incidence areas, and to provide primary clues for birth defects risk factor study.

  Methods   Using the International Atomic Energy Agency(IAEA)recommended hair washing procedure, microwave digestion methods and ICP-MS detection instrument, an ecological study was carride out to detect the levels of six necessary trace elements, that were recruited from the southern urban, southern rural, northern urban and northern rural areas of China-US birth defect surveillance system. Confounding factors including days of pregnancy, mothers' age, hair washing intervals, smoking and drinking habits were collected by questionnaire.

  Results   Geometric means of hair zinc levels for southern urban, southern rural, northern urban and northern rural areas were 220.60, 218.62, 210.01 and 186.46(μg/g)respectively. Statistical differences for hair zinc levels were found between southern and northern, urban and rural areas(P < 0.01) as a whole, but the differences only existed between northern urban and northern rural areas(P < 0.001), and no difference was found between southern urban and southern rural areas. Multi-variable analysis results showed that the living area was one of the most important factors for hair elements levels.

  Conclusion   Hair trace elements levels are different among different birth defect areas, and the distribution tendency for pregnant women's hair zinc average level is similar to that of the neural tube defects incidence in different areas. This reminds us that zinc may be related to neural tube defects.