Risk Assessment And Spatial Distribution Of Heavy Metals In Vegetables In Guangdong Province From 2014 To 2017

ObjectiveThis study was aimed?1?to research the level and temporal trend of five heavy metals?HMs?among nine types of vegetables in 21 cities in Guangdong province from 2014 to 2017;?2?to assess the health risks of five HMs among nine types of vegetables in 21 cities in Guangdong province from 2014 to 2017,including?estimated daily intake?EDI,?target hazard quotient?THQ and?carcinogenic risk?CR;and?3?to the spatial distribution of five HMs pollution in each city from 2014 to2017 is demonstrated by using map.MethodsThe levels of five kinds of HMs in 9 categories of vegetables were researched in all 21 cities of Guangdong province from 2014 to 2017.A total of 4,401 samples of individual fresh vegetables were collected from local food markets and supermarkets in eastern region of Guangdong,northern region of Guangdong,pearl river delta and western region of Guangdong.The nine categories of vegetables include bulb vegetables,stalk and stem vegetables,cabbage and brassica vegetables,leafy vegetables,fruiting vegetables,solanaceaesand legumes vegetables,root and tuber vegetables,fruiting vegetables,cucurbitsand aquatic vegetables.Sample weight per sample was no less than 500g.Five HMs concentrations were tested by ICP-MS after microwave digestion.The HMs level and health risks in each region,cities,category of vegetables,periods were calculated and assessed.The spatial display of HMs pollution in vegetables of cities was carried out by using map spatial distribution technology according to the detection rate,excess rate and comprehensive score.Results?1?Among the analyzed vegetables,their concentrations exceeded the maximum allowable concentrations?MACs?set by Chinese legislation were of 2.41%for?cadmium?Cd,1.61%for?lead?Pb,0.55%for Hg,and 0.48%for?chromium?Cr.However,excessive concentration of?arsenic?As was not observed.The concentrations of HMs had significant differences?p<0.05?in vegetable groups and regions.Cd,and Pb were the major contaminants in vegetables according to the results of principal component analysis?PCA?.During the four-year survey,a temporary rising trend was observed in As,whereas a temporary decline for Cr was found in this study.The results from hierarchical cluster analysis also demonstrated that the status of HMs contaminations in vegetables from various regions had certain changes over time.?2?EDI values of each HM at both common and high consumption levels were observed to be less than the corresponding provisional tolerable daily intakes.The THQs of individual HMs and TTHQs were less than 1,indicating low health hazards for local residents.However,high consumption of stalk and stem vegetables,leafy vegetables,and root and tuber vegetables,and high consumption of vegetables marketed in northern region?NR?of Guangdong Province resulted in TTHQs approach to 1 and may cause health risks increase.The carcinogenic risks?CRs?of Cd,Pb and As were below the threshold level(10^-6)or residual level(10^-4),suggesting low potential CR from these HMs exposures via vegetables consumption.However,highly consumed the vegetable categories with high Cd concentrations and vegetables marketed in NR resulted in the CRs of Cd and TCRs over the acceptable range,indicating that serious potential carcinogenic risks to human health.?3?The detection rate of As and Pb in various HMs increased significantly,Which for As increased from 4.64%in 2014 to 59.64%in 2017,and for Pb raised from 16.54%in 2014 to 52.36%in 2017,indicating that the As and Pb pollution in Guangdong province became serious.The excessive rate of HMs for Shaoguan city,Shenzhen city and Maoming city was the highest,and the number of cities that did not exceed the MACs was less year by year,from nine cities in 2014 to six in 2017.ConclusionHigh consumption of vegetables can increase HMs exposure,especially Cd,Pb and As,and cause noncarcinogenic and carcinogenic risks to the health of Guangdong residents.The HMs in the vegetables grown in the northern part of Guangdong Province are seriously exceeded,which poses a serious threat to the health of local residents.At the same time,the HMs pollution in the vegetables of the most cities became serious year by year,especially the detection rate of As.