Heavy Metals in Science - Definition and Examples

Heavy Metals in Science s In science, a  heavy metal is a metallic element which is toxic and has a high density, specific gravity or atomic weight. However, the term means something slightly different in common usage, referring to any metal capable of causing health problems or environmental damage. Examples of Heavy Metals Examples of heavy metals include lead, mercury and cadmium. Less commonly, any metal with a potential negative health effect or environmental impact may be termed a heavy metal, such as cobalt, chromium, lithium and even iron. Dispute over Heavy Metal Term According to the International Union of Pure and Applied Chemistry or IUPAC, the term heavy metal may be a meaningless term because there is no standardized definition for a heavy metal. Some light metals or metalloids are toxic, while some high-density metals are not. For example, cadmium generally is considered a heavy metal, with an atomic number of 48 and specific gravity of 8.65, while gold typically is not toxic, even though it has an atomic number of 79 and specific gravity of 18.88. For a given metal, the toxicity varies widely depending on the allotrope or oxidation state of the metal. Hexavalent chromium is deadly; trivalent chromium is nutritionally significant in many organisms, including humans. Certain metals, such as copper, cobalt, chromium, iron, zinc, manganese, magnesium, selenium, and molybenum, may be dense and/or toxic, yet are required micronutrients for humans or other organisms. The essential heavy metals may be needed to support key enzymes, act as cofactors, or act in oxidation-reduction reactions. While necessary for health and nutrition, excess exposure to the elements can cause cellular damage and disease. Specifically, excess metal ions can interact with DNA, proteins, and cellular components, altering the cell cycle, leading to carcinogenesis, or causing cell death. Heavy Metals of Significance to Public Health Exactly how dangerous a metal is depends on several factors, including the dose and means of exposure. Metals affect species differently. Within a single species, age, gender, and genetic predisposition all play a role in toxicity. However, certain heavy metals are of grave concern because they can damage multiple organ systems, even at low exposure levels. These metals include: ArsenicCadmiumChromiumLeadMercury In addition to being toxic, these elemental metals are also known or probable carcinogens. These metals are common in the environment, occurring in air, food, and water. They occur naturally in water and soil. Additionally, they are released into the environment from industrial processes. Source: Heavy Metals Toxicity and the Environment, P.B. Tchounwou, C.G. Yedjou, A.J. Patlolla, D.J. Sutton, Molecular, Clinical and Environmental Toxicology  Volume 101 of the series  Experientia Supplementum  pp 133-164. Heavy metals a meaningless term? (IUPAC Technical Report)  John H. Duffus,  Pure Appl. Chem., 2002, Vol. 74, No. 5, pp. 793-807

The Gentleman Fled on Foot

The Gentleman Fled on Foot The Gentleman Fled on Foot The Gentleman Fled on Foot By Maeve Maddox My local TV news team never lets me down when it comes to egregious misuse of the English language. This week they reported on a man who killed his two-month-old son by crushing his ribs and slamming his head against the side of his crib. Youll never guess what the reporter called this monstrous sicko in the introduction to the story. She referred to him as Frustrated Dad. Surely a more neutral noun than dad would have been preferable in this contextparent, for example. (For that matter, frustrated seems mild for the circumstances, but thats another post.) Newswriters would do well to weigh their choice of words against the context of the story being reported on. Moms, dads, and kids might be acceptable in reporting on Little League or a school picnic, but such folksy terms dont belong in stories about child abuse, poverty, or juvenile delinquency. The title of this post comes from a news story about a man who robbed a bank branch and escaped on foot. I cant remember if it was the reporter or the policeman being interviewed, but one of them said the gentleman fled on foot. This bizarre use of the word gentleman to refer to a bank robber is similar to the tendency of writers to apply the honorific Mr. to felons. Unless your publication has a specific policy, dont imply respect for the criminal by calling him Mr. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Misused Words category, check our popular posts, or choose a related post below:50 Idioms About Talkingâ€Å"As Well As† Does Not Mean â€Å"And†10 Types of Hyphenation Errors