Organic arsenicals toxicity

Inorganic arsenicals are more toxic than organic arsenicals, and trivalent forms are more toxic than pentavalent forms. 

Inorganic arsenic compounds are more toxic than organic arsenic compounds, and trivalent species are more toxic than pentavalent species. 

Cockell, K.A. and J.W. Hilton. 1985. Chronic toxicity of dietary inorganic and organic arsenicals to rainbow trout (Salmo gairdneri R.). Feder. Proc. 44(4) 938. 

Arsenic is an ancient and well-known hazard and, along with lead and mercury, is an important environmental contaminant. The inorganic form is far more toxic than organic arsenic, which is commonly found in seafood. Arsenic-contaminated drinking water is a worldwide problem that affects millions of people. Human exposure also occurs from arsenic-treated lumber. 

It is of historical interest that Fowler s solution, which contains 1% potassium arsenite, was widely used as a medicine for many conditions from the eighteenth century through the mid-twentieth century. Organic arsenicals were the first pharmaceutical antimicrobials and were widely used for the first half of the twentieth century until supplanted by sulfonamides and other more effective and less toxic agents. 

In September 1966 The New York Times published a report that cacodylic acid, an organic arsenic containing compound, was also being used in Vietnam.49 Cacodylic acid was a defoliant that was also toxic to man. According to the Merck Index, cacodylic acid was a dimethylarsenic acid containing 54.29 per cent arsenic, and was extremely poisonous.50 Seventy grams would kill the average 150-lb man if administered subcutaneously. 

Different roles in aquatic ecosystems, from acting as nutrients for living organisms (nitrogen and phosphorus compounds) to exerting toxic effects on such organisms (arsenic and mercury). 

Lewisite [dichloro(2-chlorovinyl)arsine] is an organic arsenical known for its vesicant properties (Rosenblatt et al., 1975). It has a molecular weight of 207.32, vapor pressure of 0.58 mm HG at 25°C, a liquid density of 1,89 g/cm at 25°C, freezing point of -18°C, boiling point of 190°C, and is negligibly soluble in water (DA, 1974). The chemical structure of lewisite is shown below. Lewisite may occur as a trans-isomer and as a cis-isomer. In aqueous solutions, the cis-isomer undergoes photoconversion to the trans-isomer (Clark, 1989). hi the presence of moisture, lewisite is rapidly converted to the more stable but highly toxic lewisite oxide (2-chlorovinylarsenous acid) (Cameron et al., 1946). 

The exact mechanism for the toxic effects of organic arsenicals is imknown. DNA alkylation and/or inhibition of glutathione-scavenging pathways are two postulated... 

The immediate onset of symptoms following exposure makes severe or systemic toxicity to organic arsenical unlikely. However, prolonged contact may lead to multiorgan involvement (Kinoshita et al, 2007 Kojima et al, 2006). Blood-bome arsenicals can trigger increased... 

Arsenic toxicity from drinking water is a major public health concern in many countries throughout the world. If exposure is to the inorganic form, the kidneys are the target organ due to its involvement in in vivo biotransformation and elimination. Very few clinical cases of toxicity are reported in humans. Most clinical cases of toxicosis are reported in animals, especially cattle and dogs, by... 

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