Metal Exposure And Health Risk Assessment Of Residents In Air Basing On Different Exposure Scenarios

Air pollution,especially air particulate pollution and other environmental problems have aroused widespread concern.Metal is one of the main components of air particulate matter.Long term inhalation of metal loaded air particulate matter may endanger human health.Due to the differences of metal exposure levels and residents’air exposure behavior patterns in different exposure scenarios,the health risks of metals in the air are not the same in different exposure scenarios.In order to understand the metal exposure and health risk of residents under different exposure scenarios,this paper first investigated the air exposure behavior pattern of residents in Lanzhou city,screened and determined the typical exposure scenarios of residents in Lanzhou Based on the difference test results of air comprehensive exposure coefficient,and then collected the air particulate matter samples(PM₁₀)under different exposure scenarios,and used inductively coupled plasma mass spectrometry（ICP-MS）and atomic fluorescence spectrometer（AFS）were used to determine the contents of Pb,Cd and As in airborne particulate matter,and analyze the exposure levels of metals in airborne particulate matter under different exposure scenarios.Finally,combined with the exposure parameters of Lanzhou residents’air exposure behavior pattern survey,the metal exposure and health risk of Lanzhou residents under different exposure scenarios were evaluated.The main results are as follows:（1）The results showed that there were differences in the exposure behavior pattern and comprehensive exposure coefficient among residents in Lanzhou.The indoor residence time of urban and rural residents in Lanzhou was more than 75%,which was 19.87 h/d and 18.61 h/d,respectively;the comprehensive indoor air exposure coefficients of urban and rural residents were 0.1773 m³/（kg·d）and 0.1664 m³/（kg·d）,the comprehensive outdoor air exposure coefficients were0.0258 m³/（kg·d）and 0.0444 m³/（kg·d）,and the comprehensive traffic air exposure coefficients were 0.0140 m³/（kg·d）and 0.0093 m³/（kg·d）,respectively Moreover,the comprehensive indoor air exposure coefficient of urban and rural residents,different ages and different genders showed significant differences（P<0.01）,the comprehensive outdoor air exposure coefficient only showed differences between urban and rural residents and between genders（P<0.01）,and the comprehensive traffic air exposure coefficient only showed significant differences between urban and rural residents（P<0.01）.（2）Based on the comprehensive air exposure coefficient,18 typical air exposure scenarios were selected and determined.Based on the difference test results of comprehensive air exposure coefficient,18 typical air exposure scenarios were selected,which were urban male indoor air exposure of 18-44 years old,urban female indoor air exposure of 18-44 years old,urban male indoor air exposure of 45-59 years old,urban female indoor air exposure of 45-59 years old,urban male indoor air exposure of 60 years old and above and urban female indoor air exposure of 60 years old and above Air exposure;rural male indoor air exposure of 18-44 years old,rural female indoor air exposure of 18-44years old,rural male indoor air exposure of 45-59 years old,rural female indoor air exposure of 45-59 years old,rural male indoor air exposure of 60 years old and above and rural female indoor air exposure of 60 years old and above;urban male outdoor air exposure,urban female outdoor air exposure,rural male indoor air exposure Outdoor air exposure of sex and rural women;urban traffic air exposure and rural traffic air exposure.（3）The exposure levels of metals in airborne particulates are different under different exposure scenarios in Lanzhou.Under different exposure scenarios,the exposure level of metals in airborne particulates in Lanzhou is Pb>As>Cd.except for the indoor exposure scenarios of men aged 60 and above in rural areas,the concentrations of As in other exposure scenarios exceeded the standard to varying degrees;the concentrations of Cd in outdoor air exposure scenarios of urban women and rural men exceeded the standard.The exposure level of As in urban and rural traffic air exposure scenarios was higher,with the median of 0.033μg/m³and 0.032μg/m³,respectively;the exposure level of Pb in urban female outdoor,urban traffic and rural traffic air exposure scenarios was higher,with the median of 0.091μg/m³,0.084μg/m³and 0.084μg/m³.The results showed that the exposure levels of Cd in urban women and rural men under outdoor air exposure scenarios were higher,with the median of 0.006μg/m³;the total exposure levels of three metals in urban women and men under outdoor air exposure scenarios were higher,with the median of 0.135μg/m³and 0.133μg/m³.（4）There are order of magnitude differences in metal exposure to airborne particulates under different exposure scenarios in Lanzhou.The results showed that the non-carcinogenic and carcinogenic exposure of metals in airborne particulates in Lanzhou under different exposure scenarios were Pb>As>Cd.The non-carcinogenic exposure of As in rural men aged 45-59 was higher,with a median of 2.67×10^-6mg/（kg·d）;the non-carcinogenic exposure of Pb in urban men aged 18-44 and 45-59 was higher,with a median of 1.31×10^-5mg/（kg·d）and 1.16×10^-5mg/（kg·d）,respectively The results showed that the non-carcinogenic exposure of Cd in urban men aged 18-44 was higher,with a median of 6.49×10^-7mg/（kg·d）;the total non-carcinogenic exposure of three metals in urban men aged 18-44 and 45-59 was higher,with a median of 1.59×10^-5mg/（kg·d）and 1.47×10^-5mg/（kg·d）,respectively.The results showed that the carcinogenic exposure of urban women aged 60 and above and rural men aged 60and above was higher,with the median of 2.21×10^-6mg/（kg·d）and 1.92×10^-6mg/（kg·d）,respectively;the carcinogenic exposure of urban men aged 60 and above was higher,with the median of 1.02×10^-5mg/（kg·d）.The results showed that under the indoor air exposure scenario,the carcinogenic exposure of men and women aged60 and above was higher,with the median of 4.97×10^-7mg/（kg·d）and 4.76×10^-7mg/（kg·d）,respectively;under the indoor air exposure scenario of men and women aged 60 and above,the total carcinogenic exposure of three metals was higher,with the median of 1.24×10^-5mg/（kg·d）and 1.14×10^-5mg/（kg·d）.（5）The risk of carcinogenic non-metallic particulate matter exposure in different areas of Lanzhou should not be ignored.The non-carcinogenic health risk of metals in airborne particulates under different exposure scenarios in Lanzhou is As>Cd>Pb.Only urban women aged45-59,urban women aged 60 and above,rural women aged 18-44 and rural men aged 60 and above have the non-carcinogenic health risk lower than 1 under indoor air exposure scenarios.The rest of the exposure scenarios exceed the safety value of1（HQ>1）to varying degrees,and have potential risks There is no non-carcinogenic health risk for Cd and Pb.The non-carcinogenic health risk of As was higher in rural men and women aged 45-59 under indoor air exposure scenarios,with the median of0.69 and 0.61 respectively;the non-carcinogenic health risk of Pb was higher in urban men aged 18-44 and 45-59 under indoor air exposure scenarios,with the median of 0.25 and 0.22 respectively;the non-carcinogenic health risk of Cd was higher in urban men aged 18-44 under indoor air exposure scenarios The results showed that the total non-carcinogenic health risks of urban men aged 18-44,rural men aged 45-59 and urban men aged 45-59 were higher,with the median of 1.07,0.99 and 0.99,respectively.（6）The health risk of metal carcinogenesis in airborne particulate matter under different exposure scenarios in Lanzhou is still acceptable.The carcinogenic health risk of metals in airborne particulates under different exposure scenarios in Lanzhou is As>Cd>Pb,in which the carcinogenic health risk of As and Cd is acceptable,and the carcinogenic health risk of Pb is negligible.In different exposure scenarios,urban women aged 60 and above and rural men aged60 and above had higher carcinogenic health risk under indoor air exposure scenarios,with a median of 3.76×10^-5and 3.27×10^-5,respectively;urban men aged60 and above and women aged 60 and above had higher carcinogenic health risk under indoor air exposure scenarios,with a median of 4.69×10^-7and 3.87×10^-7,respectively;The results showed that the carcinogenic health risk of Cd was higher in male and female indoor air exposure scenarios,with the median of 3.43×10^-6and3.28×10^-6,respectively;the total carcinogenic health risk of three metals was higher in urban women aged 60 and above and rural men aged 60 and above,with the median of 3.98×10^-5and 3.45×10^-5,respectively.To sum up,metals in air particulate matter of different exposure scenarios in Lanzhou have different degrees of pollution.The metal exposure and health risk are higher in indoor exposure scenario,followed by outdoor exposure scenario and the lowest in traffic exposure scenario.There was no total non-carcinogenic health risk（HI<1）for metals in airborne particulates only under outdoor exposure scenarios of urban men,outdoor exposure scenarios of rural women,outdoor exposure scenarios of urban traffic and rural traffic,while the other exposure scenarios exceeded the safety value（HI≥1）in varying degrees,with potential non-carcinogenic health risk;while the carcinogenic health risk of metals was acceptable.In different air exposure scenarios,the total non-carcinogenic and total carcinogenic health risks of metals in indoor air particulates were higher than those in outdoor and traffic;men were higher than women;in different age groups,the total non-carcinogenic risk of metals in residents aged 18-44 was higher,and the total carcinogenic risk of metals in residents aged 60 and above was higher.Therefore,it should be advocated to carry out in-depth exposure and health risk assessment of metals in airborne particulates under typical exposure scenarios,so as to provide important scientific basis for accurate prevention and control of health risks.