Research On The Pollution Of Polycyclic Aromatic Hydrocarbons In The Atmosphere And Food In Xianlin Area Of ??Nanjing And Its Impact On The Health Of Residents

Polycyclic aromatic hydrocarbons(PAHs)are widely spread in the environment,which can enter human body through breathing,diet,and skin.They are the first discovered carcinogens of the largest amount and researchers found that PAHs are carcinogenic,teratogenic and mutagenic.Epidemiological studies have shown cancer incidence is significantly related to PAHs exposure.PAHs in the environment has become a hot research topic.However,former researches paid less attention on PAHs in gas phase and particulate phase,as well as in food.Nanjing is a typical city in the eastern of China and it was chosen as the study area in this study.This study took PAHs in atmosphere and food as subjects,and collected atmospheric samples from spring to summer and three categories of food samples including vegetables,meat and cereals being widely consumed by Nanjing Xianlin residents.16 USEPA priority PAHs were determined by gas chromatography mass spectrometry.This study discussed seasonal variation of pollution level,source,inhalation exposure and health risk for PAHs in gas and particulate phase and pollution level,source,dietary exposure and health risk for PAHs in food.The total amount of atmospheric PAHs was within the range of 19.33?77.53 ng/m3 and the mean value was 43.97 ng/m3,with the concentration of BaP exceeding the national standard limit value.Compared with other cities in China,the concentrations of PAHs in the atmosphere in Nanjing Xianlin were at low levels,but were higher than those in foreign developed regions.The total amount of PAHs in vegetables,pork,chicken and rice was 101.45 ng/g,278.59 ng/g,231.43 ng/g and 59.96 ng/g respectively.The concentrations of PAH4 in pork exceeded the EU standard limit value of food,which indicated the food had been polluted by PAHs to some extent.Seasonal change of total concentrations in gas PAHs,particulate PAHs and total PAHs was spring>summer,and the concentrations of gas PAHs in spring and summer were higher than those of particulate PAHs.Three and four ring PAHs were dominated in gas phase and the proportion of median-ring and high-ring PAHs in particulate phase was larger than that in gas phase.The main form of median-ring and high-ring PAHs was gradually converted into particles from gas phase.The proportion of each ring PAHs in food samples was different:3 ring PAHs>4 ring PAHs>2 ring PAHs>5?6 ring PAHs.Through the source analysis,it was found that the main source of atmospheric PAHs in spring was vehicle,coal and biomass combustion and the contribution rates were 61.62%and 38.38%respectively;whereas the main source of atmospheric PAHs in summer was vehicle and coal,coke oven and contribution rates were 54.51%fand 45.49%respectively.In food,the main source of PAHs in vegetables was from coal combustion,and the main source of PAHs in meat was from oil,coal combustion and gasoline vehicle exhaust emissions.The main source of PAHs in grain was from incomplete combustion of coal or other biomass and diesel exhaust emissions.The ranking of inhalation exposure in decreasing order was:male adults>female adults>male adolescents>female adolescents>male seniors>female seniors>boys>girls.The inhalation exposure in spring was higher than that in summer.The values of dietary exposure in BaP and PAH4 in decreasing order was:children>adolescents>adults>seniors and the dietary exposure for children was the most.The contribution of pork in dietary exposure of BaP was the highest,followed by chicken and rice,and vegetables were the lowest.The contribution of vegetables in dietary exposure of PAH4 was the highest,followed by pork and chicken,and rice was the lowest.Incremental lung cancer risk(ILCR)to PAHs for population groups of different age and gender was different significantly.It was found that the cancer risk of adults was higher than others groups,followed by children.in terms of gender,females showed higher risk than males,whereas in terms of season,the cancer risk in summer was higher than that in spring.The TLCR values at 87.64th,90.60th,66.20th,90.64th,87.14th,90.44th,68.30th,90.12th percentile for boys,male adolescents,male adults,male seniors,girls,female adolescents,female adults and female seniors in spring were greater than 10-6,indicating potential lung cancer risk.The ILCR values at 85.64th,88.84th,63.78th,88.88th,85.14th,88.70th,65.78th,89.18th percentile for the above eight groups in summer were greater than 10-6,indicating potential lung cancer risk.The approach of margin of exposure(MOEs)was used to calculate the carcinogenic risk caused by dietary exposure for eight groups.The MOE value in the case of BaP among eight groups was greater than 10000,which showed that there was little effect on the health of Nanjing Xianlin residents.The MOE value in the case of PAH4 among eight groups was lower than 10000,which showed that it may have impact on Nanjing Xianlin residents to some extent.It was found that children showed higher dietary exposure risk than other age groups and the dietary exposure risk of females was higher than males.