Distribution, Accumulation, and Risk Assessment of Pb and Cd in the Tea Plant Leaves, Black Tea, and Soil from Different Tea Plantations in Lahijan, Iran

Abstract

Since heavy metals (HM) exist in the soil due to industrial activity and the usage of pesticides and fertilizers, monitoring the content of these pollutants is very significant. The current research aimed to determine the concentrations of cadmium (Cd) and lead (Pb) in the tea plant leaves, black tea, and soil and look for their correlations. Twenty-seven (27) samples were divided into three groups of tea plant leaves, black tea, and soil from the same tea plantations originating from Lahijan, Iran. The concentrations of Pb and Cd in samples were determined using a flame atomic absorption spectrophotometer. After that, some analyses were conducted to find the correlation between the content of Pb and Cd in tea plant leaves, black tea, and soil, and their health risks were evaluated. In leaves, black tea, and soil, the mean contents for Cd were 0.001, 0.044, and 0.044 ppm, whereas those for Pb were 0.501, 0.939, and 2.093 ppm, respectively. The results showed that Cd and Pb concentration means in tea plant leaves, black tea, and soil samples were lower than the guidelines recommended by EU, WHO, and national Iranian standards (P < 0.05). The values of the non-carcinogenic hazard quotients (HQ) and the hazard index (HI) were below 1, indicating that these two HMs will not adversely affect consumers' health through the oral pathway of drinking tea. However, more attention should be paid to monitoring the content of HMs in soil. This research recommends that soil Pb contamination should be managed to ensure safe tea production in the study area. An effective management strategy appears necessary to ensure the quality and safety of tea plantations, as well as to reduce the risk of the accumulation of HMs in tea.