Arsenic environmental factors

Gao, S., Burau, R.G. (1997). Environmental factors affecting rates of arsine evolution from and mineralization of arsenicals in soil. J. Environ. Qual. 26 753-63. 

Environmental factors have been suggested as triggers for the autoimmune response. These suggested factors include viral infections, infant feeding practices, toxins such as /V-nitroso derivates, vaccinations, and arsenic exposure, but for the most part evidence supporting these finks is lacking. 

TABLE 7-1 Occupations and other environmental factors at risk for arsenic exposure ... 

Although microorganisms are known to be involved in arsenic volatilization, many environmental factors, such as pH, redox potential, presence of other ele-... 

Arsenic, chromium, mercury, selenium, and tin have been the object of numerous investigations. Because some of them are classified as probable human carcinogens23-25 (strictly speaking, some of their species), the accurate assessment of concentration and speciation in environmental matrices is enormously important. Unfortunately, such factors as chemical reactions between species, low concentration, microbial activity, redox conditions, as well as the presence of other dissolved metal ions, may cause the amounts and distributions of chemical species in a sample to vary. In response to these problems, analytical research efforts have focused on developing techniques enabling the original valence state of the metals to be preserved. Table 2.3 lists some of these stabilization methods. 

Arsenic and selenium demonstrate many similarities in their behavior in the environment. Both are redox sensitive and occur in several oxidation states under different environmental conditions. Both partition preferentially into sulfide minerals and metal oxides and are concentrated naturally in areas of mineralization and geothermal activity. Both elements occur as oxyanions in solution and, depending on redox status, are potentially mobile in the near-neutral to alkaline pH conditions that typify many natural waters. However, there are also some major differences. Selenium is immobile under reducing conditions while the mobility of arsenic is less predictable and depends on a range of other factors. Selenium also appears to partition more strongly with organic matter than arsenic. 

Arsenic in aquatic environments is usually more concentrated in sediments and pore water than in the overlying water column (Ahmann et al., 1997 Smedley and Kinniburgh, 2002 Williams, 2001). The most abundant forms of arsenic are arsenate [As(V)] and arsenite [As(III)], but methylated forms can occur in mine-impacted environments (i.e., methylarsenic acid and dimethylarsenic acid) (Smedley and Kinniburgh, 2002) see Chapter 9.02. The principal pathway of arsenic toxicity is through dietary exposure to sediment and suspended particulates by fish, followed by human consumption. Environmental exposure to arsenic is a causal factor in human carcinogenous and other related health issues. Chronic exposure symptoms in humans include hyperkeratosis, hyperpigmentation, skin malignancies, and peripheral arteriosclerosis. Water provides the dominant pathway for arsenic exposure in humans (Williams, 2001). 

This review describes factors concerning the safety and environmental effects of organic arsenic, antimony and bismuth compounds. The factors involve the production and use of the elements, toxicity, pollution, metabolism (alkylation), health effect assessment, fate and so on. 

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