Pollution assessment and health risks evaluation of (metalloid) heavy metals in urban street dust of 58 cities in China

In this research, we conducted a statistical analysis of ten (metalloid) heavy metals, including Cu, Hg, Cd, Zn, Pb, As, Ni, Cr, Co, and Mn in urban dust of 58 cities in China from 2000 to 2018, and then we analyzed the statistic characters, pollution statue, and health risks of ten heavy metals. Results showed that (1) the maximum (average) values of ten (metalloid) heavy metals in the street dust of 58 Chinese cities all exceeded Chinese background values, and there were obvious differences in contents of heavy metals of Hg, Zn, Co, Cr, and As between industry cities and common cities. A provincial spatial distribution analysis revealed large variations of distributions of heavy metals Cu, Zn, Pb, and Cr, which distributed in cities mainly located in southern, central, and eastern China, ranging from relatively low to high levels, while Ni, Co, and Mn mainly distributed in southern and central China. This is mainly associated with the mining of the cities. (2) I-geo analysis showed that there was no obvious Ni, Mn, or Co pollution in street dust, while the other tested heavy metals had a range of low to high levels of pollution, in particular, seven metals among them had low to extremely strong levels of pollution (I-geo values between 0 and 7.154), and the average I-geo values were in the following order: Cd>Hg>Zn>Pb>Cu>As>Cr>Mn>Co>Ni. (3) Health risks evaluation showed that of the three exposure ways, the HQ(ing) from hand-mouth intake was the most common exposure route for both children and adults, especially for children, followed by skin absorption and respiration ways. This research showed that the HI value for children was higher than 1, indicative of no carcinogenic risks, while the HI values for both male and female were lower than 1, indicative of carcinogenic risks; calculation of carcinogenic risk through respiratory route showed that the risks of five elements were within the range 10(-6)-10(-4), indicative of carcinogenic risk, among which Cr accounting exceeded 90% of total, which needs to be paid more attention to.