Scale and causes of lead contamination in Chinese tea Wen-Yan Han a , Fang-Jie Zhao b, * , Yuan-Zhi Shi a , Li-Feng Ma a , Jian-Yun Ruan a a Key Laboratory of Tea Chemical Engineering, Ministry of Agriculture; Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 3100008, China b Agriculture and Environment Division, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Received 10 December 2004; accepted 23 April 2005 32% of Chinese tea samples exceeded the national maximum permissible concentration for Pb. Abstract We investigated the scale and causes of Pb contamination in Chinese tea. Lead concentrations in 1225 tea samples collected nationally between 1999 and 2001 varied from !0.2 to 97.9 mg kg ÿ1 dry weight (DW), with 32% of the samples exceeding the national maximum permissible concentration (MPC) of 2.0 mg kg ÿ1 DW and a significant difference between tea types. There was an increasing trend in tea Pb concentration from 1989 to 2000. Proximity to highway and surface dust contamination were found to cause elevated Pb concentrations in tea leaves. Furthermore, Pb concentration in tea leaves correlated significantly and positively with soil extractable Pb, and negatively with soil pH, suggesting that root uptake of Pb from soils also contributed to Pb accumulation in tea. Potential contributions to human Pb intake from drinking tea were small at the median or national MPC Pb values, but considerable at the highest concentration found in the study. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Pb contamination; Tea; Human intake; Atmospheric deposition 1. Introduction Lead (Pb) is a physiological and neurological toxin that can affect almost every organ and system in the human body (Agency for Toxic Substances and Disease Registry (ATSDR), 1999; Joint FAO/WHO Expert Committee on Food Additives, 2000). The most sensitive part of the body is the central nervous system, particularly in children. The most critical effect of Pb at low concentrations is reduced cognitive development and intellectual performance in children. Lead also damages kidneys and the reproductive system. Lead poisoning, especially in young children, is an environ- mental and public hazard of global proportions (Adriano, 2001). The main exposure to Pb of the general non-smoking adult population is from food and water, whilst for infants and children, food, air, water and dust or soil are the main potential sources of exposure (Joint FAO/WHO Expert Committee on Food Additives, 2000). Foods may contain Pb from the environment (e.g. uptake by plant roots or foliage) or from food processing and storage (e.g. containers). The Joint FAO/WHO Expert Committee on Food Additives established a provisional tolerable weekly intake (PTWI) of Pb at 25 mg kg ÿ1 body weight for infants and children, and later extended this value to people of all age groups (Joint FAO/WHO Expert Committee on Food Additives, 1993). Human Pb intake in developed countries has declined significantly during the last two decades as a result of the ban on the use of * Corresponding author. Tel.: C44 1582 763133; fax: C44 1582 760981. E-mail address: fangjie.zhao@bbsrc.ac.uk (F.-J. Zhao). 0269-7491/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2005.04.025 Environmental Pollution 139 (2006) 125e132 www.elsevier.com/locate/envpol