Geochemical and environmental factors controlling exposure to cerium and magnesium in Uganda

The presence of elevated levels of dietary Ce and deficient levels of dieta ry Mg in southern India have been assigned as potential environmental cofac tors in the aetiology of endomyocardial fibrosis. However, environmental ex posure to Ce in tropical environments, where EMF is prevalent, is poorly un derstood because of wide variation in geochemical environments and local di etary habits. This paper describes collaborative studies based in Uganda to define environmental exposure pathways within a region where EMF is endemi c, and represents the most common form of infantile heart condition. Data a re presented from a survey of major foodstuffs, soils and waters which indi cate that the most probable pathway for Ce exposure is from dust and inadve rtent carriage of soil. In addition to substantiating observations made in southwestern India, detailed studies of Ugandan soils, dusts and waters ind icate that Ce within the Ugandan environment is controlled by the presence of sub-20 mu m particles in the soil. These are probably present as seconda ry rare earth minerals rather than monazite as assumed by workers in India. (C) 1998 The Natural Environment Research Council.