Metal Element-trace

See also: ETM

The concept of metal element-traces , or ETM (in the past heavy metals ), is currently a relatively fuzzy concept, without scientific definition, technical or legal which is unanimously recognized. As example, an information paper to the French Senate “the effects of heavy metals on the environment and health”, indicated: “Name heavy metals is however a current name which has neither scientific base, nor legal application”.

  • Certains authors defines heavy metals as the metal elements having a Density higher than a certain value (this minimal value varying between 4000 kg/m 3 and 5000 kg/m 3 according to the authors).
  • Of others defines as heavy metals the metal elements ranging between copper and lead in the periodic Tableau of the elements (thus excluding iron, chromium).
  • For others it acts of all the metal elements as from the fourth period of the periodic table of the elements. even sometimes
  • By confusion, taking into account the potentially toxic character of composed of some of heavy metals (mercury, lead, cadmium in particular), one includes in the category of heavy metals certain toxic elements like the Arsenic (metalloid), even some organic compounds. It is better in this case speech d'" elements traces".

Uses

Much ETM has a utility in the biological process: for example iron is an essential component of the Hémoglobine, the Zinc, the Cuivre are Oligo-élément S essential.

All the metal element-traces are present naturally at the state of traces in the ground. The human activity can have reinforced this presence; indeed, number of ETM play a big role in the daily life:

  • the Iron (Fe) and its alloys, Steel S, stainless steels;
  • the Lead (Pb) for the accumulator batteries (in particular for the cars), pipings, the weldings, the Painting S anti Corrosion (Minium) and the Ammunition S. the Shot S of lead of the ammunition of hunting and shooting-trap, lost in the environment, represented approximately 8.000 T of plomb/an only for France about the year 2000; these toxic ammunition is avian source of Saturnisme and at the man…;
  • the mercury (Hg) for very many uses of which the dental alloys and the batteries; source of hydrargism.
  • the Uranium (U) for the skittles of certain boats, the Ammunition S anti-shielding (Uranium depleted);
  • the chromium (Cr), like red Pigment and for the chromium plating of parts;
  • the Copper (Cu), in the field of electronics like like fungicide (copper sulfate, in particular used during the treatment of the vines);
  • the money (Ag) for the jewelry and silverware, the silver Photography, the mirrors, of many industrial uses (in particular electric and electronic), the currencies and medals;
  • the Gold (With) for the jewelry, the invaluable objects, the electrical contacts, in dentistry;
  • the Zinc (Zn) for the Galvanization of the Steel, and for castings used in the car;
  • the Titanium (Ti) because of its chemical inertia for the construction of chemical engines, or for the clothes industry of prostheses (Prosthesis of the hip for example);
  • the Nickel (Ni) for the stainless steels.

The solid or liquid fossile fuel combustion (coal, produced oil origin) is also likely to reject metals in ashes, vapors and smoke.

Toxicological impact

The toxicological impact of the ETM depends on their chemical form (named " species chimique"), of their concentration, the environmental context, the possibility of passage in the chain of the alive one.

One distinguishes in particular three metals mercury, Plomb, Cadmium, for which on the one hand one could not highlight of positive role for the biological activity, and which on the other hand can be at the origin of grave diseases; for example the lead ingestion causes the Saturnisme, particularly serious in the child. It would be abusive to put on the same plan as these three metals of metals considered as biocompatible and used in surgery or dentistry like titanium and gold, or of the base metals like iron. Other metals can be toxic in certain forms (Chrome, Cuivre,…).

The use of certain ETM thus is strictly regulated, even prohibited in certain applications. The rejection in the environment at the end of the use must be avoided, and these recycled metals.

See too

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