| The development of cities is accompanied by many environmental problems,of which the most concerned is the impact of heavy metals on the urban environment.Heavy metals are most likely to enter the human body through the inhalation of vegetables and food chain,which are harmful to human health.As one of the fastest growing cities in Western China,Guiyang has some pollution in the process of development.Therefore,this paper takes heavy metals in dust and vegetables as the research object,adopts the most commonly used in vitro simulation method,studies the bioaccessibility of heavy metals in dust and vegetables from two ways:respiratory inhalation and hand oral intake,and carries out health risk assessment for the population in this urban area.The main results are as follows:（1）The average contents of the six heavy metals Cu,Pb,Zn,Cd,Ni,and Cr in dust were 165.41,64.41,966.61,1.92,133.26,and 164.86 mg·kg-1,which were 5.16,1.82,9.71,2.92,3.41,4.99,and 1.72 times of the background values of soil in Guizhou Province,respectively,indicating that each heavy metal was enriched in dust to different degrees.From the spatial distribution,it can be inferred that most of these six heavy metals are related to transportation as well as industrial construction,and none of the heavy metal elements in vegetables exceeded the limit value,indicating that there is no obvious pollution situation.（2）In the simulated respiratory system,the relative order of bioaccessibility of heavy metals in dust is Zn>Pb>Cu>Ni>Cd>Cr,which is speculated to be related to the occurrence forms of heavy metals.In the simulated digestive system,the relative order of bioaccessibility of heavy metals in the gastric stage is Ni>Zn>Cd>Cu>Pb>Cr,and the relative order of bioaccessibility in the intestinal stage is Cu>Zn>Ni>Cd>Pb>CR respectively.The bioaccessibility of most heavy metals in the gastric stage is higher than that in the intestinal stage,while the bioaccessibility of Cu in the intestinal stage is higher than that in the gastric stage because Cu can complex with trypsin and bile salts.（3）The bioaccessibility of heavy metals in vegetables in the simulated gastrointestinal stage shows that Cu has the highest bioaccessibility in leafy vegetables,the lowest bioaccessibility in stem vegetables,the highest bioaccessibility in melons,fruits and stem vegetables,the lowest bioaccessibility in leafy vegetables,the performance of Zn is basically consistent with Pb,and Cd is mainly in some leafy vegetables,The bioaccessibility of Ni in melon,fruit and stem vegetables is higher,while that in leafy vegetables is smaller,while the performance of Cr is basically the same as that of Ni.（4）The results of health risk assessment in dust showed that the total non carcinogenic risk of children in respiratory inhalation route was2.75×10-5,the total non carcinogenic risk under the hand oral intake route is 2.58×10-2,the total non carcinogenic risk of adults in the respiratory inhalation route is 2.06×10-5,the total non carcinogenic risk under the hand mouth route is 1.31×10-2.The non carcinogenic risk of children and adults in both exposure routes does not exceed 1,which is lower than the risk threshold,indicating that they do not have non carcinogenic risk;The results of carcinogenic risk showed that the total risk values of Cd,Cr and Ni in children and adults were 6.38×10-7 and 8.71×10-9,respectively.Compared with the established carcinogenic risk standard,the carcinogenic risk of children and adults can be ignored,and the health risk assessment results of vegetables show that heavy metals in all kinds of vegetables will not pose health risks to the urban population. |
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