Asen là nguyên tố 52 phổ biến nhất trong lớp vỏ của trái đất với một sự phong phú tự nhiên trung bình khoảng 1,5-3 mg / kg. Nó là phổ biến trong môi trường, xảy ra từ cả hai nguồn tự nhiên và con người, và cả hai có thể đặt ra một mối đe dọa đối với sức khỏe con người. | 7 Environmental Aspects of Arsenic Toxicity J. Thomas Hindmarsh The University of Ottawa and the Ottawa Hospital Ottawa Ontario Canada Charles O. Abernathy . Environmental Protection Agency Washington . Gregory R. Peters Philip Analytical Services Inc. Bedford Nova Scotia Canada Ross F. McCurdy InNOVAcorp Dartmouth Nova Scotia Canada 1. INTRODUCTION Arsenic is the 52nd most common element in the earth s crust with an average natural abundance of approximately mg kg. It is ubiquitous in the environment occurring from both natural and anthropogenic sources and both may pose a threat to human health. Numerous control mechanisms for arsenic exist in the environment but the natural cycling of this element throughout the various envi- Copyright 2002 Marcel Dekker Inc. ronmental compartments air water soil and biota is complex and poorly understood. The main sources of human exposure to arsenic are from the drinking water supply and food. A decade ago it seemed that chronic arsenic poisoning was a rare and diminishing problem. However since then it has again emerged in parts of Asia with unprecedented fury where tens of millions of people are exposed to toxic levels in their drinking water probably as a consequence of increased agricultural irrigation. In recent years the toxic potential both carcinogenic and noncarcino-genic of arsenic in drinking water has been intensely studied. However further research is needed to determine the toxic threshold for this element as well as to understand the mechanisms governing the release of soluble arsenic into the various environmental compartments and how this can be modified. The health effects of environmental arsenic and its geochemistry have recently been reviewed 1-3 . 2. CHEMISTRY AND TOXICITY Arsenic is a metalloid belonging to group 15 old group 5 of the periodic table N P As Sb Bi . It exists predominantly in nature as the oxyanion with an oxidation state of either 3 or 5 however the -3 state also exists in .
