Chapter Two - Arsenic in environment: historic, concepts, occurrence and problems

Abstract

Arsenic (As) occurs in the environment both naturally and by anthropogenic sources. It can be present in water, soils, minerals, sediments, and dust. Anthropogenic sources include use of As-contaminated irrigation water, mining, and food additives. Throughout history, As was widely used as a poison, a therapeutic agent for various diseases such as cancer and syphilis, and as pesticide. It was also used in mining and metallurgy, wood preservation, fertilizers, feed supplements, urban and industrial waste. Chemical forms of As depend on some environment conditions such as pH, redox potential, mineral composition, organic matter content and microorganisms. Considering the inorganic arsenic compounds, arsenic trioxide, arsenic trichloride, arsenic pentoxide, arsenic acid and arsenates are the most common. Common organic arsenic compounds include arsanilic acid, methylarsonic acid, dimethylarsinic acid, and arsenobetaine. Inorganic As is more toxic than organic forms of this element. Exposure to As occurs mainly through water and food threatening food safety and human health. Dietary sources of As include rice-based products, seaweeds, fish, shellfish, chicken, and mushrooms. Therefore, continuous environmental, food and toxicological monitoring is necessary to assure food safety and human health. This chapter explores areas around the world with high levels of arsenic from natural and anthropogenic sources and its toxicological effects.