Research On Critical Factors And Health Risk Assessment Of Fluorine,Aluminum And Heavy Metals In Tea

Tea is an important economic crops of China.In recent years,with the rapid development of economy and the increasing of pollutants,resulting in heavy metals pollution of soil.The heavy metals in tea can not only absorbed by the food chain enter human body,which posed a threat to people’s physical health,but also related to the development of tea industry of China and tens of millions of farmers economic benefits.Furthermore,Tea plants are accumulator of F and Al,and accumulated them in leaves.The high contents of F and Al in tea leaves may affect the health of people.The purposes of the present study were to investigate the F,Al and heavy metals(Mn,Cu,Pb,Cr and Cd)in tea plants(Camellia sinensis(L.)O.Kuntze)and a relationship to the F、Al and heavy metal content of soils and soil parameters(pH,organic matter,cation exchange capacity,total phosphorus and soil bio-available phosphorus),by studying the distribution characteristics and migration regularity of F、Al and heavy metals in tea and soil and investigating the effects of varieties,seasons and tea leaf maturity on the accumulation of F、Al and heavy metals in tea plants;explore how different manufacturing processes affect the content of F、Al and heavy metals in tea;estimate the health risks resulting from exposure to F、Al and heavy metals via tea drinking for adults.Mainly the following conclusions:1.Correlation analysis was performed to study the relationship between tea leaf F、Al and heavy metals and soil F,Al and heavy metals,and the different soil parameters of pH,CEC,OM,T-P and Av-P.The F,Al,Cu,Pb and Cr in tea leaves,respectively,showed significant positive correlation with soil WS-F,Bio-Al,Bio-Cu,Bio-Pb and Bio-Cr,and correlation coefficients were 0.53,0.58,0.67,0.65,and0.47(P < 0.05 or P < 0.01),respectively.These results suggest that WS-F and bioavailable metals in soil was the most important soil factor affecting F,Al and heavy metals accumulated in tea leaves.2.The season had an effect on the content of F,Al and heavy metals in tea leaves.And they follow the following pattern: F,Al,Mn: summer > autumn > spring.Pb:autumn > spring and summer.Cr: summer and autumn > spring;Cd: autumn >summer > spring;Copper: seasonal variation is not obvious.By analyzing the content of F,Al,Mn,Cu,Pb,Cr and Cd in 8 different tea varieties,the F,Al,Mn and Cd hadlarge differences in 8 varieties of tea plants,while the Cu,Pb and Cr had small difference in 8 varieties of tea plants.3.The content of F,Al and heavy metals in tea leaves with tea leaf maturity had linear relationships.Among them,except of Cu content in tea leaves declined with tea leaf maturity,the F Al,Mn,Pb,Cr and Cd in tea leaves were increased as the leaves matured4.The effect of manufacturing process on the content of F,Al and heavy metals from tea leaves.The tea manufacturing process did not introduced fluoride contamination.It was apparent that withering step in black tea,white tea and oolong tea processing increasing the leaching of F.Compared to fresh tea leaves,the level of fluoride in the withered leaves increased between 9.3 and 15.8%,and the rolling or fermentation did not affect the leaching of F in tea leaves.For white tea,compared to fresh tea leaves,the Mn content in white tea rose 7.14%.For green tea,black tea,yellow tea,dark tea and oolong tea,tea processing processes had no significant effect on the content of Al,Mn and Cd in tea leaves,while the content of Cu,Pb and Cr in these five kinds of tea increased between 20.04 and 29.87%,between 15.28 and26.39% and between 7.93 and 10.27%,respectively,and the pollutions mainly come from the rolling stage,in this process tea leaves are more closely in contact with the metal surface of the machine.5.The content of F,Al,Mn,Cu,Pb,Cr and Cd in 115 commercial teas were determined.The average content of F,Al,Mn,Cu,Pb,Cr and Cd was 81.70 mg/kg,743.85 mg/kg,584.10 m/kg,14.16 mg/kg,1.47 mg/kg,0.50 mg/kg and 15.15 mg/kg,respectively.the Monte Carlo simulation was carried out to estimate distributions of exposure and risk for tea drinker.Ninety-fifth percentile HQ values for F,Al,Mn,Cu,Pb,Cr and Cd were 0.68,0.28,0.81,0.11,0.02,9.79×10-5and 6.84×10-3,respectively,which were below 1.Therefore,it could concluded that F,Al and heavy metals intake from drinking tea over a long term could not cause significant health risk.