Selenium distribution in the local environment of selected villages of theKeshan Disease belt, Zhangjiakou District, Hebei Province, People's Republic of China

The distribution of Se in cultivated topsoils, grains, human hair and drink ing water has been studied in 15 villages from a Keshan disease area of the People's Republic of China, villages being classified into 3 groups accord ing to the Keshan disease incidence in the local population. In grain, hair and water the total Se follows expected trends; i.e. the highest concentra tions are found in the villages where there is no incidence of Keshan disea se. However, the soils from the high-incidence Keshan disease villages have the highest total Se content, an apparent contradiction, as Keshan disease is a response to a Se deficient environment. Soil analyses suggest that th e organic content of the soils is a major factor in controlling the availab ility of Se and it is the high-incidence Keshan disease villages that have the most organic-rich soils. Although higher in total Se, the organic-rich soils have little bioavailable Se resulting in a Se deficient food chain. S oil pH is also seen to be a related factor in restricting the availability of Se and all the grain samples collected on soils with a pH <7.6 had a tot al Se content of less than 10% of the total soil Se. In an environment that can be classified as Se deficient small changes in the soil organic conten t and pH can have a critical affect on the Keshan disease status of a villa ge. (C) 1999 Nerc. Published by Elsevier Science Ltd. All rights reserved.