| Indoor dust is a complex and heterogeneous mixture of organic and inorganic particulate matter. This medium is composed of material that is derived from a variety of interior and exterior sources. And the pollutants concentrations in indoor dust were generally higher than outdoors. In order to understand the pollution characteristics of heavy metals in indoor dust in residential areas of Huainan city and their health risk assessment. To understand the pollution characteristic and sources of heavy metals in indoor dust and health risk to residents in Huainan city. The samples of indoor and outdoor dusts in different districts and seasons, soils in residential areas and hair from children and adults were collected. Zn, Pb, Cu, V, Cr, Ni, Co, As and Hg contents of indoor dusts, outdoor dusts, soil and ha ir in Huainan city were determined by inductively coupled plasma-optical emission spectroscopy(ICP-OES). The sources and influencing factors of heavy metals in indoor dust were analyzed by PCA and ANONA, and the health risks of heavy metals to residents were evaluated by health risk assessment model. The main research conclusions of this study were as follows:(1) The average contents of Zn, Pb, Cu, Cr, Ni and Hg in indoor dust were higher than their corresponding background values of Huainan soil, with the mean values of 6.50, 4.51, 6.67, 1.31, 2.60, 1.31 times the background values, respectively. As, Co and V contents were lower than the background values. The difference of heavy metals contents in different districts indoor dust was obvious, the average contents of Co and Zn in indoor dust of TJA district were higher than that of other districts, Cu and Ni contents in XJJ district were higher than other districts, the average contents of Cr and V in DT district were higher than other districts, average contents of As, Hg, Pb in indoor dust of PJ district were higher than other districts. the As concentration in indoor dust in spring was higher than other seasons, the contents of Co, Ni, V and Zn in indoor dust summer were higher than other seasons, the average concentration of Cr, Cu and Pb in indoor dust in autumn were higher than other seasons,the Hg concentration in winter was significantly higher than other seasons.(2) In gastric phase, the bioaccessible of Co, Ni, V and Zn in indoor dust were higher than that in intestinal phase. The elements of Pb, Cu and Cr showed the opposite pattern which the bioaccessible in intestinal phase was higher than those in gastric phase. The bioavailability decreased in the order of Pb(76%) > Zn(60 %) > Co(55%) > Ni(53%) > Cu(46%) > V(38%) > Cr(25%). The bioavailability regional difference of heavy metals in indoor dust decreased in the order of: Zn, Ni, Co: DT>XJJ>TJA>PJ; Pb: TJA>PJ>XJJ>DT; Cu: DT>TJA>PJ>XJJ; V: XJJ>TJA>DT> PJ; Cr: DT>TJA>XJJ>PJ. In addition to Cu, the largest bioavailability of all elements appear in the spring indoor dust, and Cu appear in the winter. The bioavailability of all elements in the summer indoor dust were low.(3) The results of correlation analysis and PCA indicated that Cu, Zn, Ni in indoor dust mainly comes from automobile emission. As, Co and V in indoor dust mainly come from the natural source. Cr and Pb mainly come from the interior sources such as metal objects and paint. Hg mainly comes from coal combustion. The results of t test or ANOVA with least square difference methods indicated that the Cr, Cu and Pb concentration in indoor dust of Huainan city inf luenced by interior paint. The contents of Zn, Ni in indoor dust of wood floor material were higher than that of other materials. Cu, Zn and As levels in indoor dust were highly significantly associated with family personnel number. Smoking can lead to the increase of Cu concentration in indoor dust. Due to differences of environment, transport and coal-burning activity in different areas, Cu, V, Zn, Hg levels were highly signif icantly associated with sample location; Cu, Zn contents in indoor dust were affected by traffic density around the house. Houses that regularly open their windows appeared to have a signif icantly higher As, Hg level than those of that occasionally their windows opened, and cleaning frequency will lead to changes of Co, V contents in indoor dust.(4) Hg in indoor dust of Huainan city was ranked as very high enrichment, the elements of Zn, Cu, Pb, Ni, Cr were ranked as significant enrichment, and Co, As, V in indoor dust have no enrichment.. Co, Cr, V and As in indoor dust of Huainan city were ranked as unpolluted, Ni was ranked as slightly polluted, Pb was ranked as moderately polluted, Zn and Cu w ere ranked as moderately to heavily polluted, Hg was ranked as heavily polluted.The elements of Co, V, As and Cr in four districts were ranked as unpolluted, or slight polluted. Ni in PJ district was ranked as unpolluted, was ranked as slight polluted in TJA and DT districts, and ranked as moderately polluted in XJJ district. Cu in PJ and DT districts was ranked as moderately polluted, and moderately to heavily polluted in TJA and XJJ districts. Pb in PJ district was ranked as moderately to heavily polluted, and moderately polluted in other three districts. Zn was ranked as moderately polluted in DT district, and moderately to heavily polluted in TJA, PJ and XJJ districts. Hg in PJ district was ranked as heavily to extremely polluted, heavily polluted in DT and XJJ districts, and moderately to heavily polluted in TJA district.The elements of Co, Cr, V, As were ranked as unpolluted in different seasons. Ni in the autumn and winter was ranked as unpolluted, slight pollut ed in the spring, and moderately polluted in the summer. Pb was ranked as slightly polluted in the summer, moderately polluted in the winter and spring, and moderately to heavily polluted in the autumn. Cu in the spring and autumn indoor dust was ranked as moderately to heavily polluted, moderately polluted in the summer and winter. Zn was ranked as moderately to heavily polluted in different seasons. Hg in the spring and winter indoor dust was ranked as heavily polluted, moderately to heavily polluted in the autumn, and was ranked as moderately polluted in the summer.(5) The potential ecological risk of heavy metals in indoor dust in residential areas of Huainan city decreased in order of Hg > Cu > Pb > Ni > Zn> Co > As > Cr > V. The comprehensive potential ecological r isk of heavy metals in indoor dust of Huainan city present a strong ecological r isk. The potential ecological risks of Co, Cr, Ni, V, Zn, As in indoor dust in different districts were in slight risk; Cu in DT and PJ districtsat a slight risk, and at a medium risk in TJA and XJJ districts; Pb in PJ district at a medium risk, at a slight risk in other three districts; Hg in four districts showed a strong ecological r isk. The potential ecological risks of Zn, Co, Cr, Ni, V in summer were higher than those in other seasons, the max potential ecological risk of As appear in the spring, the largest risk of Hg appear in winter, the biggest ecological risks of Cu and Pb present in autumn.(6) Except Hg, average daily exposure levels of all elements were characterized by hand-to-mouth ingestion > dermal contact > respiratory inhalation. Hand-to-mouth ingestion is the main pathway to indoor dust for children and adults because of their hand-to-mouth activity. Average daily exposure level of Hg were characterized by Hg steam inhalation > hand-to-mouth ingestion > dermal contact > respiratory inhalation. The total non-carcinogenic risks of all elements for children were characterized by: Pb > Cr > As > Hg > V > Cu > Ni > Co > Zn, for adults: Pb > Cr > Hg > As > V > Cu > Ni > Co > Zn. The carcinogenic risks of Co, Ni, As and Cr in indoor dust decreased in the order of Cr > Ni > Co > As.The Zn exposure dose in different districts were the largest, Hg exposure dose in different districts were the lowest. The total non-carcinogenic risks of Pb in indoor dust in PJ, XJJ, TJA districts were the highest. The highest total non-carcinogenic risk element in DT distict was Cr. And the lowest total non-carcinogenic risk element in four districts was Co. In addition to Hg vapor inhalation, the largest exposure dose element for three exposure routes in indoor dust of different seasons was Zn, followed by Pb, and Hg exposure levels was the lowest. The carcinogenic risks of Co, Cr, Ni, As in indoor dust of different districts and seasons within the safety threshold, showed that Co, Cr, Ni, As in indoor dust to children and adults without the carcinogenic risk.(7) The health risk assessment results based on bioavailability showed that children's exposure dose, non-carcinogenic and carcinogenic risks of heavy metals in indoor dust were higher than those of adults. The non-carcinogenic risks(HQ) of heavy metals in indoor dust to children and adults were characterized by Cr > Pb > Ni > Cu > V > Zn > Co. The regional difference of the total non-carcinogenic risk(HI) of heavy metals in indoor dust was characterized by: PJ > TJA > DT > XJJ. The regional difference of total carcinogenic risk for children was characterized by: DT > PJ > TJA > XJJ; for adults: XJJ > TJA > DT > PJ. The seasonal difference of non-carcinogenic risk for children and adults decreased in the order of summer > spring > autumn > winter, and the seasonal difference of carcinogenic risk decreased in the order of spring > summer > autumn > winter.Based on time-activity pattern, average daily exposure levels of all elements were characterized by hand-to-mouth ingestion > dermal contact > respiratory inhalation. The non-carcinogenic risks of Ni for three exposed ways were the lowest. The largest non-carcinogenic risk element by hand-to-mouth ingestion was Pb, and was Cr by dermal contact and respiratory inhalation. The total non-carcinogenic risk of all elements were characterized by Pb > Cr > As > V > Co > Cu > Zn > Hg > Ni. |
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