Exposure to metal mixtures and human health impacts in a contaminated area in Nanning, China Yujing Cui a , Yong-Guan Zhu a, * , Rihong Zhai b , Yizhong Huang a , Yi Qiu b , Jianzhong Liang b a Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085, Beijing, China b Guangxi Institute of Occupational Health, 530021, Nanning, China Available online 23 June 2005 Abstract Cadmium and lead have been identified as very toxic metals, which are widely present in the environment due to natural and anthropogenic emissions. Many studies have shown that the food chain is the main pathway of cadmium and lead transfer from the environment to humans. It is well documented that many factors will affect their transfer through food chains. Previous investigations on heavy metals were mostly concentrated on one contaminant in isolation. However, in real environments, exposure to mixtures of metals is ubiquitous such that cadmium pollution is invariably being associated with lead and zinc, etc. This study focuses on the contamination and health effects of the metal mixtures. For this purpose, a dietary survey was taken for 3 groups in Nanning in October 2002. Samples of soils, plants (vegetables), urine and blood of humans were measured for Cd, Fe, Cu, Zn, Ca and Pb, in addition, the urinary indicators of renal dysfunction Albumin (ALB), N-acetyl-beta-d-glucosaminidase (NAG), Beta-2-microglobulin (h 2 -MG) and Retinol-binding protein (RBP) in urine were also measured. Results showed that soil contamination with metal mixtures had caused significant renal dysfunction of the local residents living in the contaminated area, and the dose – response curve was somewhat altered by the mixed contamination of Cd and Pb as well as the intake of other minerals. The importance of mixtures of metal contamination and human health are also discussed in this paper. D 2005 Elsevier Ltd. All rights reserved. Keywords: Cadmium; Lead; Metal mixture; Renal dysfunction; Soil contamination 1. Introduction Metals are ubiquitous in the environment either naturally or anthropogenically. Both industry and agriculture has contributed considerably to the elevated concentrations of heavy metals through waste disposal, smelter stacks, atmos- pheric deposition, fertilizer and pesticide use and the application of sewage sludge in arable land. As a result, an increased metal uptake by crops and vegetables grown for human consumption is often observed. It is well known that some metals, such as zinc (Zn), copper (Cu) and cobalt (Co) are essential for most biological systems including humans at appropriate levels; while others, such as cadmium (Cd) and lead (Pb) are highly toxic to plants, animals and human. However, generally speaking, the excessive accumulation of most heavy metals and metalloids in soils and plants may pose serious health risks to humans and exert adverse impacts on the ecosystem itself (Granero and Domingo, 2002; McLaughlin et al., 1999, 2000). For example, the accumu- lation of Cd in human bodies (principally in kidney and liver) can cause renal dysfunction and bone disease such as Itai-Itai (Nordberg, 1996). In China there are several studies demonstrating that environmental contamination with Cd has resulted in poor health among residents near smelters (Cai et al., 1990; Nordberg et al., 1997; Jin et al., 2002). The major public health concern of cadmium exposure in a general population is lifetime accumulation and possible renal damage through dose in the food chain, which has attracted much attention worldwide (Syers and Goldfeld, 2001). Cadmium is detoxified in the liver by binding to metallothionein (MT) to produce the inert complex, CdMT. 0160-4120/$ - see front matter D 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.envint.2005.05.025 * Corresponding author. E-mail address: ygzhu@mail.rcees.ac.cn (Y.-G. Zhu). Environment International 31 (2005) 784 – 790 www.elsevier.com/locate/envint