Accumulation of Heavy Metals in Tea Leaves and Potential Health Risk Assessment: A Case Study from Puan County, Guizhou Province, China

Abstract

This study features a survey of the concentrations of aluminum (Al) and heavy metals (Mn, Pb, Cd, Hg, As, Cr, Ni, Cu, and Zn) in tea leaves and the corresponding cultivation soils (0–30 cm), carried out in Puan County (Guizhou Province, China). The average concentrations of Al, Mn, Pb, Cd, Hg, As, Cr, Ni, Cu, and Zn in the soil were 106 × 103, 214, 20.9, 0.09, 0.12, 17.5, 121, 27.8, 131.2, and 64 mg·kg−1, respectively. The heavy metals’ pollution indexes in the soil can be ranked as follows: Cu > Cr > Hg > As > Ni > Zn > Pb > Mn > Cd. The soil was moderately polluted by Cu because of the high geochemical background value of Cu in the area. The potential environment risk index (RI) showed that 7.69% out of the total sample sites were within the moderate level. Moreover, the ranges of Al, Mn, Pb, Cd, Hg, As, Cr, Ni, Cu, and Zn concentrations in young tea leaves were 250–660, 194–1130, 0.107–0.400, 0.012–0.092, 0.014–0.085, 0.073–0.456, 0.33–1.26, 6.33–14.90, 14.90–26.10, and 35.8–50.3 mg·kg−1, respectively. While in mature tea leaves, they were 4300–10,400, 536–4610, 0.560–1.265, 0.040–0.087, 0.043–0.089, 0.189–0.453, 0.69–2.91, 3.43–14.20, 6.17–16.25, and 9.1–20.0 mg·kg−1, respectively. Furthermore, the concentrations of Pb, Cu, As, Hg, Cd, and Cr in young tea leaves and mature tea leaves were all lower than the standard limit values (5.0, 30, 2.0, 0.3, 1.0, and 5.0 mg·kg−1 for Pb, Cu, As, Hg, Cd, and Cr, respectively) in China. Besides, the accumulation ability of tea leaves to Mn was the strongest, and the average bioconcentration factor (BCF) of Mn in mature tea leaves was 12.5. In addition, the average target hazard quotients (THQ) were all less than one for the young tea leaves and the average aggregate risk hazard index (HI) to adults was 0.272, indicating that there was not a potential health risk for adults through the consumption of the infusions brewed by young tea leaves. However, for mature tea leaves, the percentage which HI values were above one was 38.46%, and the risk to adults via the consumption of mature tea infusions were mainly contributed by Mn and Al.

Trace Elements in Leaf Extracts of Eucalyptus grandis Traditionally Used to Treat Common Cold and Flu

“…The physiology of the plant and PTE characteristics may explain the greater accumulation of Cr, Pb, and Zn in mature leaves compared to young leaves. In a study of heavy metal content of tea leaves in Puan County, China, by Zhang et al ., Cr, Pb and Zn concentrations were higher in mature leaves compared to young leaves 24. However, Doganlar et al .…”

Health Functions and Related Molecular Mechanisms of Tea Components: An Update Review

“…Besides, the THQ and HI values would decrease as the infusion time increased, so it was suggested to discard the first tea infusion and consume the later ones [214]. In addition, some elements might be accumulated in tea during plantation, and the most strongly accumulated ones are Mn, Al, and F, which could induce poisoning symptoms, cognitive dysfunction, fluorosis of bone, and other adverse effects in humans [213,226,227]. Environmental and plant factors, such as the soil condition, variety, season, and maturity, might influence the contents and distribution of certain elements in tea.…”

Assessing heavy metal pollution and potential ecological risk of tea plantation soils

“…Previous studies in tea plantations have focused on the investigation of soil fertility and physicochemistry, and the influence of beneficial trace metals on tea quality [16,17] .…”