| Due to the refractory,high enrichment and toxicity,heavy metal elements will cause serious and long-term threats to human health.Heavy metal pollution,as a key concern of food safety and human health,has received extensive attention from all over the world.Because the enrichment characteristics of heavy metals by organisms are different,and the heavy metal pollution in different regions,seasons and food materials is different.Therefore,this paper aims to investigate the basic information and behavioral parameters of the surveyed subjects in Chengguan District of Lanzhou City and a village in Yuzhong County.The collection of food and dietary samples is also conducted.The contents of mercury,chromium,arsenic,cadmium and lead in the diet are determined.The single-factor pollution index method and the Nemerow comprehensive pollution index method are used to evaluate the status of heavy metal pollution in food ingredients.The health risk assessment model recommended by（US EPA）evaluates dietary heavy metal exposure and health risks.The main results are as follows:（1）There are differences in the retention levels of heavy metals for different food ingredients in the investigated areas,and some of them exceed the standard.The retention level of heavy metals for different food materials in urban areas is higher than that in rural areas,and in winter slightly higher than in summer.Hg,Cr and As all exceed the standard to varying degrees;The occurrence levels of Hg in aquatic products,Cr in beans and products,As in eggs,Cd in vegetables and Pb in meat are relatively high,which are 0.0343 mg/kg（51.16%）,21.7872 mg/kg（57.27%）,and0.1639 mg/kg（30.02%）,respectively.0.0187mg/kg（29.66%）and 0.0433mg/kg（22.39%）;Cr in beans and products,grains and vegetables（3.5553mg/kg～21.7872mg/kg）,As in eggs And Hg（0.0156 mg/kg）in vegetables all exceed the national allowable limit.Only Pb and Cd do not exceed the standard.（2）The pollution assessment shows that to some extent,there is heavy metal pollution in different food ingredients in the surveyed area.Except for some types of vegetables,the comprehensive pollution index of other food materials is higher in urban than in rural areas,and only the comprehensive pollution index of heavy metals in beans and soy products has obvious seasonal differences,that is,summer（20.890）is significantly higher than winter（13.944）.Grain milled products（6.371）,paddy rice（7.688）,beans and products（16.259）,beans and tubers in vegetables（11.503）and brassica leafy vegetables（4.363）are heavily polluted ingredients;fresh vegetables（2.792）and celery（2.246）belong to moderately polluted food;aquatic products（1.167）belong to lightly polluted food.The single-factor pollution index of Cr in milled grains,paddy rice,beans and their products,fresh vegetables,Brassica leafy vegetables,beans and tuber vegetables,and Hg in Brassica Leafy vegetables are all>3,reaching severe Pollution level,Cr in cereals（excluding rice）and celery is moderately polluted;As in aquatic products is slightly polluted.（3）The dietary exposure levels of different metals in the surveyed areas vary greatly,and there are urban-rural and seasonal differences.The dietary heavy metal exposure levels of the population in the survey area from high to low are:Cr（2.76mg/kg）>Pb(1.44×10-1mg/kg)>As(2.73×10-2mg/kg)>Cd(7.08×10-3mg/kg)>Hg(4.88×10-3mg/kg),there is no order of magnitude difference between urban and rural areas.Except for Cr,Hg,As,Cd and Pb are all higher in urban than in rural areas;urban Hg,Cd and Pb exposure levels And the Hg exposure levels in rural areas are higher in men than in women,and the exposure levels of other metals are higher in women than in men;except for Cr,the dietary exposure levels of the other four metals are higher in 45-59 year olds.Except for Cd,there are seasonal differences in the exposure levels of other metals.Hg and Pb in summer are higher than those in winter,while Cr and As are opposite.The exposure levels of Hg,Cr and Cd and Cd and Pb in men in winter are lower than those in women,and As and Pb and As in women in winter In summer,Hg and Cr are the opposite;the exposure levels of Hg,Cr and Cd in winter are higher among 45-59 year olds,and the Cd exposure level in summer is 18-44 years old=45-59 years old>60 years old and above.（4）There are urban-rural and seasonal differences in the average daily exposure（ADI）of heavy metals in the survey area,and the Cr exposure is at a high level.The ADI of dietary heavy metals in the survey area is Cr>Pb>As>Cd>Hg in descending order,and Cr exposure is the highest at 4.18×10-2 mg/（kg·d）.In terms of urban-rural differences,except for Pb,which is slightly higher in rural areas than in urban areas,Hg,Cr,As and Cd are higher in urban areas than in rural areas.Except for the ADI of Hg,which is higher in males than in females,other metals are higher in females than in males;45～The ADIs of five metals in urban areas and Cr,Cd and Pb in rural areas in 59-year-olds are at high levels,ranging from 6.84×10-5 to 5.19×10-2,and the ADIs of Hg and As in people over 60 years old in rural areas higher value.In terms of seasonal differences,except for Cr,which is higher in winter than in summer,the other metals are higher in summer than in winter;except that the ADI of Hg in males is higher than that in females in summer,the rest are higher in females than in males;in winter,four metals except As are higher in 45-59 year old.The ADIs of Cr,Cd and Pb are at higher levels in summer,the ADIs of Hg are higher in the 18-44 year old in summer,and the ADIs of As in the people aged 60 and above are higher in both seasons.（5）There is a potential non-carcinogenic risk of dietary As exposure in the survey area,and Cr and As may have a carcinogenic risk.Among the five heavy metals in the survey area,the non-carcinogenic risk of dietary As exposure is HQ>1,and the total carcinogenic risk of Cr and As exposure is more than 10-4,indicating that the metals in the survey area have potential non-carcinogenic risks and unacceptable carcinogenic risks to residents,which all show that the city is higher than the rural area,the female is higher than the male,the 60-year-old and over>45-59 years old>18-44 years old,the HI is higher in summer than in winter,and the cancer risk is slightly higher in winter than in summer.To sum up,the occurrence level of heavy metals in food materials in the surveyed area is greatly affected by food types,urban and rural differences,and there are different degrees of excess;the dietary heavy metal exposure levels and exposure levels in the survey areas are different in urban and rural areas,seasons,different genders and different age groups.There is a potential non-carcinogenic risk of dietary As exposure in the survey area,and Cr and As have a carcinogenic risk.Therefore,for the survey area,it is necessary to focus on the prevention and control of food materials with excessive heavy metals and heavy metal pollution that cause carcinogenic and non-carcinogenic risks. |
