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2.2.4 Arsenic Sulphide
ОглавлениеArsenic sulphide, in its natural form has been in use for longest time. Similar to any other natural products, Arsenic trisulfide had a wide range of industrial use, including tanning agent, often with with indigo dye. Orpiment is found in volcanic environments, often together with other arsenic sulfides, mainly realgar (“ruby sulphur” or “ruby of arsenic”). Similar to mercury, this naturally occurring chemical was used throughout history as a potent poison or a medicine (Frith, 2013). Arsenic was used in traditional Chinese as well as Indian medicine. In addition, it was popular as a cosmetic product in eye shadow in the Roman era. In traditional Chinese medicine, preparations can be obtained in the form of coated or uncoated pills, powder or syrups. Different studies have shown that the majority of traditional Chinese medicines, such as Chinese herbal balls, show high doses of As varying between 0.1 and 36.6 mg per tablet, causing patients to get intoxicated by the high As dose and Indian ayurvedic herbal medicine products are also known to cause lead, mercury and As intoxication.
Avicenna recommended arsenic with the gum of pine for asthma. He also prescribed arsenic in honey water, for a wide range of remedies, including for herpes esthiomenos of the nose (Aegineta, 1847). Avicenna discussed the use of white, red, and yellow arsenic, all being used in their natural state. It was much later that ‘refined’ arsenic emerged. For instance, arsenic was known as early as the fourth century B.C., when Aristotle referred to one of its sulfides as “sandarach,” or red lead (now known as As4S4). It was only in 1250 that Albertus Magnus, a German philosopher and alchemist that isolated the element. Of course, the word arsenic comes from the Persian word “zarnikh,” which means “yellow orpiment,” which the Greeks adopted as “arsenikon”. This is commonly denominated as Arsenic trisulfide (As2S3), although natural state contains other chemicals that are in perfect balance with the molecular form. Of course, the more common form is crystalline oxides, As2O3 (white arsenic). The most common form, however, is the Arsenopyrite (FeAsS), an iron arsenic sulfide, also called mispickel.
Nowadays, the therapeutic use of As is making a comeback in modern medicine. Arsenic-trioxide, for instance, is used in treating patients with relapsed acute promyelocytic leukemia (APL). However, the notion of natural state of arsenic being different from synthetic one’s is absent.
Long before being hailed as “the arsenic that saved” in early 20th century (Vahidnia et al., 2007), Muslim scholars considered Arsenic sulphide as a chemical of crucial pharmaceutical value. The word arsenic is derived from the Persian zarnikh and Syriac zarniqa, later incorporated into ancient Greek as arsenikon, which meant “masculine” or “potent” and referred primarily to orpiment, or yellow arsenic. The word became arsenicum in Latin and arsenic in old French, from which the current English term is derived (Vahidnia et al., 2007).
In post-Renaissance Europe, the use of arsenic as a poisoning agent became common. Its application in getting rid of wealthy people became so popular that by the 17th century France, white arsenic became known as poudre de succession, the ‘inheritance powder’ (Vahidnia et al., 2007). In the 19th century, the same tactic was used to commit insurance fraud. During that era, one of the most infamous case was that of Goeie Mie (‘Good Mary’) of Leiden, The Netherlands, who poisoned at least 102 friends and relatives between 1867 and 1884, distributing arsenic-trioxide (ATO) in hot milk to her victims after opening life insurance policies in their names. Of the 102 people poisoned, 45 persons became seriously ill, often with neurological symptoms and 27 persons died; 16 of whom were her own relatives (De Wolff and Edelbroek, 1994).
Research during that period led to the development of post-mortem detection of poison, followed by decrease in incidents of poisoning with arsenic. During the 19th century, European women applied arsenic powder to whiten their faces as well as to their hair and scalp to destroy vermin. It was also thought that arsenic consumption by women gave “beauty and freshness” to the skin. For the first time in Europe, medicinal applications of arsenic are found in late 18th century, when various chronic disorders were being treated with arsenic (Bentley and Chasteen, 2002). Arsenic continued to be used in cosmetics well into the early twentieth century and this was a common source of accidental poisoning.
When arsenic is heated, it oxidizes and releases an odor similar to that of garlic. Striking various arsenic-containing minerals with a hammer might also release the characteristic odor. At ordinary pressure, arsenic, like carbon dioxide, does not melt but sublimes directly into vapor. Liquid arsenic only forms under high pressure.
Curiously, alchemists gave emphasis on characterizing material in terms of mercury and arsenic. Mercury, lead and arsenic are effective mitotic poisons (turbagens) at particular concentrations, due to their known affinity for thiol groups and induce various types of spindle disturbances. New Science classifies these clastogenic effects to be S-dependent. The availability of cations affect the number of aberrations produced quantitatively. Plants, following lower exposure, regain normalcy on being allowed to recover (Patra et al., 2004). However, as usual New Science does not distinguish between natural arsenic and processed arsenic, thereby obscuring any usefulness of the research findings.
Historically, New Scientists5 have focused on medicinal effects of arsenic when it comes to finding any positive aspect of arsenic. Citations of medicinal applications range from Ancient China to Ancient Greece through Ancient India (Doyle, 2009). Hippocrates (469–377 BC) recommended arseniko as a tonic whilst Dioscorides (c. 54–68AD) recommended it for asthma. A Greek surgeon‐herbalist working in Nero’s army, he made extensive observations on asthma, including the use of realgar mixed with resin, inhaled as a smoke for the relief of cough or taken as a potion for asthma. Reportedly, it was used to kill Britanicus in 55 AD during the reign of Emperor Nero (37–68AD).
Egyptologists claim that ancient Egyptians used arsenic to harden copper at least 3000 years ago. This was confirmed by Islam et al. (2010), who reviewed ancient technologies and found them to be totally sustainable because they used no artificial mass or energy source. They also discussed the fact that such chemicals were added in the embalming fluid during processing of mummies. Of course, the Medieval Islamic golden era saw numerous applications through alchemy. However, the role of arsenic in material processing has drawn little attention from New Scientists. In Europe, during the New Science era, the use of arsenic is synonymous with processed derivatives of arsenic, rather than naturally occurring version. Graeme and Pollack (1998) described how artificial processing of arsenic can render both mercury and arsenic into toxic agents. They pointed out that Greeks and Romans continued to use natural arsenic throughout the Medieval era for various medical purposes. Even during the 1800s, arsenic remained in use for medical purposes in treating leukemia, psoriasis, and asthma. Of interest is the fact that the Fowler’s solution was not withdrawn from the US market until the 1950s. Meanwhile, Erlich and Bertheim produced nearly 1000 compounds of arsenic to be used in the treatment of syphilis; the use of such compounds was not curtailed until after the advent of penicillin in 1943. The arsenic-containing drug melarsoprol (Mel B) is still the drug of choice for treating African trypanosomiasis at the meningoencephalitic stage 1, 2, 3, 4. Note that commercial use of electricity began in 1870s. Although it is unknown among New scientists, the use of electricity for thermal alteration renders a process unsustainable. In the meantime, while natural penicillin was discovered in 1928 by Alexander Fleming, Professor of Bacteriology at St. Mary’s Hospital in London, mass production was possible only after synthetic version of penicillin was created. This transformation from natural penicillin to Benzylpenicillin (C16H18N2O4S) first took place in 1942 (Fischer and Ganellin, 2006). This transition from natural to artificial is symbolic of what has happened in sustainability considerations, natural being sustainable while artificial (or synthetic) being unsustainable.
Arsenic may occur in an inorganic or an organic form. The inorganic arsenic compounds include the arsenites, the arsenates, and elemental arsenic. The organic arsenic compounds include arsine and its organic derivatives. In modern era, synthetic or inorganic arsenic has been the only one used for commercial applications. In all these applications, arsenic is never in its natural form and all the byproducts are inherently toxic to the environment. For instance, arsenic is a byproduct of the smelting process for many metal ores such as, cobalt, gold, lead, nickel, and zinc. The natural form of arsenic was used in ancient and medieval era for similar applications. It seems even in modern Europe as late as 19th century arsenic was used in paints and dyes for clothes, paper, and wallpaper (Meharg 2003). Even then, arsenic for the production of green pigments following the synthesis in the late eighteenth century of copper arsenite was in its toxic form. These pigments were widely used in wallpapers. In damp rooms, fungi living on the wallpaper paste turned the arsenic salts into highly toxic trimethylarsine. Arsenic pigments were responsible for untold numbers of cases of chronic illness and many deaths (Meharg, 2003).
The source of both organic and inorganic arsenicals are naturally occurring minerals, such as, arsenopyrite (FeAsS), realgar (As4S4) and orpiment (As2S3). As these erode, they react with moisture and oxygen to form arsenites and arsenates that are water soluble and consequently end up in both surface and groundwater. Some of these chemical forms and oxidation states cause acute and chronic adverse health effects, including cancer (Hughes, 2002). The metabolism involves reduction to a trivalent state and oxidative methylation to a pentavalent state. The trivalent arsenicals, including those methylated, have more potent toxic properties than the pentavalent arsenicals. The exact mechanism of the action of arsenic is not known, but several hypotheses have been proposed. What is missing in this analysis is the role of artificial chemicals. At a biochemical level, inorganic arsenic in the pentavalent state may replace phosphate in several reactions. In the trivalent state, inorganic and organic (methylated) arsenic may react with critical thiols in proteins and inhibit their activity. However, this ‘organic’ in New Science doesn’t mean that an artificial state has been avoided. As such, potential mechanisms include genotoxicity, altered DNA methylation, oxidative stress, altered cell proliferation, co-carcinogenesis, and tumor promotion cannot be tracked to artificial chemicals. A better understanding of the mechanism(s) of action of arsenic will make a more confident determination of the risks associated with exposure to this chemical.
In surface waters, these chemicals can be absorbed by algae that then convert them to arsenosugars, arsinolipids and arsenobetaine. In surface waters, these can be absorbed by algae that then convert them to arsenosugars, arsinolipids and arsenobetaine. Fish and other forms of marine life feed on these algae and concentrate the arsenic compounds. When the same arsenic compounds are absorbed by plants, similar but less complex reactions take place and further dilution occurs when they are passed on to grains.
Figure 2.5 Shows the pathway followed by the original naturally occurring ore, containing arsenic. Most arsenic in the terrestrial environment is found in rocks and soils. Arsenic in surface and ground water is mostly a mixture of arsenite and arsenate. Although New Science designates various components in molecular form, in reality molecules are fictitious and never exist in isolation. During the pre-New Science era chemical equations were not written in molecular or atomic form, hence the words, such as ‘air’ (instead of Oxygen), ‘moisture’ (instead of H2O) and chosen.
Figure 2.5 Pathway followed by arsenic chemicals.
This figure shows that in order for arsenic to travel natural pathway, the entire chain of air and moisture has to be free of synthetic chemicals. In the post industrial revolution, major sources of arsenic include the combustion of coal, nonferrous metal smelting, and the burning of agricultural wastes. These are inherently toxic to the environment. Similarly, each chemical containing arsenic that has been widely used as herbicides, fungicides, wood preservatives, desiccants, cattle and sheep dips, and dyestuffs is necessarily synthetic or artificially processed. Today, arsenic continues to be widely used in agriculture, in glass and ceramics, as a metal alloy, and in semiconductors and other electronic devices – all causing irreparable harm to the environment. It is no surprise that the entire branch of toxicology deals with only artificial type of arsenic products (Hughes, 2002).