Evaluation of Lead, Cadmium and Copper in Black Tea Leaves in Mazandaran Factories, Spring and Summer 2011

Background and The main source of trace elements in plants is soil and nutrients of their growth medium. On the other hand، growth of tea is affected by some variables such as relative humidity of weather، temperature difference between day and night and and length of the day which are different in each season. This study aimed to investigate the effects of harvest time on tea leaf heavy metals in Mazandaran province. The study was carried out in Mazandaran food control laboratory on 32 samples of black tea leaves، obtained from Mazandaran factories. The elements were analyzed using graphite furnace and flame atomic absorption spectrophotometer. To compare the mean with standard threshold and independence of variables one-sample t-test and chi square were used respectively. Cu، cd and pb mean contents، as mg/kg in spring and summer، was (23. 14±10. 3، 30. 19 ±12. 8،)، (0. 16±0. 07، 0. 4±0. 68) and (2. 25±1. 21، 2. 33± 1. 34)، respectively. Pb content in spring and summer and then cd content in summer was significantly higher and cu content in summer and spring was significantly lower than Iran’s standard threshold (p≤0. 05). There were no significant differences between harvest season and metal content. Control of trace elements content in tea is necessary due to the high per capita consumption of tea in Iran which makes it one of the most important ways to trace element intake.