0.05). The correlative analysis on the relationship between IQ and those 4 elements contents showed that the correlative coefficients were 0.593 for calcium, 0.384 for zinc, 0.449 for iron and -0.637 for lead respectively, their P values were all below 0.01. Conclusion The children's IQ was positively correlated with the contents of calcium, zinc and iron in hair, and negatively correlated with the contents of lead in their hair.

Perchlorate is a new emerging environmental pollutant that is very stable and persistent,and it can diffuse rapidly in the environment. The environmental problems caused by perchlorate have attracted a great attention from many environmental scientists. However,up to now,a few reports on perchlorate pollution have been reported in China. In this paper,for perchlorate as an environmental pollutant,the sources,characteristics,detecting methods and toxicological effect on human body were reviewed,and the further research topics were presented.

Objective To develop a core competence evaluation index system for preventive medicine undergraduates.Methods Following the scientific,systematic and applicable principles,we proposed evaluation index system of core competence for professional medical prevention and selected 35 experts for three rounds expert consultation on the index system by using Delphi method.The basic situation,the positive and authority degree of experts and all levels of index weight coefficient were analyzed using SPSS 13.0 software.Results The core competence evaluation index system for preventive medicine undergraduates included six dimensionalities,fifteen secondary indicators and forty-nine tertiary indicators.The six dimensionalities included professional value behavior (0.25),professional knowledge and skills (0.28),basic specialized knowledge (0.20),communication (0.13),information management (0.06) and systems thinking (0.08).Conclusion The establishment of the evaluation system can provide a scientific and objective reference for the evaluation of the core competence of medical students.