![]() In this review, we will be focused on the arsenicals in the trivalent and pentavalent states that are found in the environment and to which humans are exposed. Arsine and arsenides have a valence of (–III). Elemental arsenic has a valence state of (0). The valence states of arsenic of environmental interest are the trivalent (III) and pentavalent (V) states. Elemental arsenic tends to be nonductile.) In the environment, arsenic is found in inorganic and organic forms and in different valence or oxidation states. (A metal has luster, conducts heat and electricity, and is malleable and ductile. The substances are ranked on frequency or occurrence, toxicity, and potential for human exposure.Īn understanding of the chemistry of arsenic is needed to appreciate the toxicology of this metalloid, which shares properties of metals and nonmetals. This list is comprised of substances found at hazardous waste sites on the National Priorities List. Many of these areas have been identified, and efforts are being made to either remediate these areas or limit access to them.Īrsenic is the number one substance in the most recent ( ATSDR, 2007a) Comprehensive, Environmental, Response, Compensation and Liability Act (CERCLA) Priority List of Hazardous Substances published by the Agency for Toxic Substances and Disease Registry (ATSDR). Although most typical environmental exposures to arsenic do not pose a health risk, several areas of the world contain arsenic from natural or anthropogenic sources at levels that create a toxicological concern. However, most laymen do not know or understand that we are constantly exposed to arsenic because it is naturally present in the environment, is used in commercial products, and has medical applications. This is because arsenic has a long history of being a poison, both intentional and unintentional, to humans. The word “arsenic” elicits a fearful response in most people. With advances in technology and the recent development of animal models for arsenic carcinogenicity, understanding of the toxicology of arsenic will continue to improve. Two key areas are the interaction of trivalent arsenicals with sulfur in proteins and the ability of arsenic to generate oxidative stress. The mode of action of arsenic for its disease endpoints is currently under study. A major concern of ingested arsenic is cancer, primarily of skin, bladder, and lung. Depending on the dose, chronic arsenic exposure may affect several major organ systems. Acute effects of arsenic range from gastrointestinal distress to death. Trivalent arsenic is generally more toxicologically potent than pentavalent arsenic. ![]() ![]() Metabolism of arsenic, catalyzed by arsenic (+3 oxidation state) methyltransferase, is a sequential process of reduction from pentavalency to trivalency followed by oxidative methylation back to pentavalency. Environmentally relevant forms of arsenic are inorganic and organic existing in the trivalent or pentavalent state. There are several structural forms and oxidation states of arsenic because it forms alloys with metals and covalent bonds with hydrogen, oxygen, carbon, and other elements. In some areas of the world, high levels of arsenic are naturally present in drinking water and are a toxicological concern. Arsenic has a long history of use as a homicidal agent, but in the past 100 years arsenic, has been used as a pesticide, a chemotherapeutic agent and a constituent of consumer products. The metalloid arsenic is a natural environmental contaminant to which humans are routinely exposed in food, water, air, and soil.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |