Читать книгу Geochemistry - Группа авторов - Страница 8

Willis Gwenzi

Biosystems and Environmental Engineering Research Group, Department of Soil Science and Agricultural Engineering, University of Zimbabwe, Mt. Pleasant, Harare, Zimbabwe

Abstract

Serpentinitic ultramafic geological systems contain toxic geogenic contaminants posing significant human health risks. The current chapter presents an overview of the nature, occurrence, behavior, and human health risks of toxic geogenic contaminants in serpentinitic geological systems. The geogenic contaminants include toxic metals (Co, Cr, Fe, Mn, Ni, and Zn), chrysotile asbestos, and rare earth elements. Occupational exposure occurs via inhalation in mining, milling, sculpturing, engraving, and carving industries. Non-occupational exposure include inhalation, and ingestion of toxic geogenic contaminants in contaminated geophagic earths, wild foods, herbal medicines, and water. Human exposure risk factors in Africa include weak and poorly enforced occupational and environmental regulations, consumption of contaminated foods and water, and lack of health surveillance systems. The prevalence of geophagy, high dietary intake of iron coupled with genetic disposition also increases iron overload and its health risks among native Africans. The human health risks of chrysotile (e.g., asbestosis, cancers) and toxic metals and rare earth elements (e.g., oxidative stress) are summarized. Human health risks may also occur via synergistic interactions among toxic geogenic contaminants (e.g., chrysotile and toxic metals), and with other health stressors (e.g., infectious diseases). Finally, mitigation measures to safeguard human health and future needs are highlighted.

Keywords: Serpentines, ultramafics, medical geology, toxic metals, chrysotile asbestos, rare earth elements, asbestosis, human exposure pathways