Lead :: essays research papers

choke is a lustrous, silverymetal that tarnishes in the presence of air and becomes a dull bluishgray. Soft and flexible, it has a miserable melting point (327 C). Its chemicalsymbol, Pb, is from plumbum, the Latin word for wetworks, because of falls extensive use in ancient wet pipes. Itsatomic number is 82 itsatomic weight is 207.19.Lead and lead compounds female genital organ be highly toxicwhen eaten or inhaled. Although lead is absorbed very slowly into thebody, its rate of excretion is even slower. Thus, with constant exposure,lead accumulates gradually in the body. It is absorbed by the red bloodcells and circulated through the body where it becomes concentrated inthe soft tissues, especially the liver and kidneys. Lead can cause damagein the central nervous system and apparently can damage the cells makingup the blood-brain barrier that protects the brain from many bruising chemicals.Symptomsof lead poisoning include loss of appetite, weakness, anemia, vomiting,and con vulsions, sometimes leading to permanent brain damage or death.Children who ingest chips of old, lead-containing paint or are undefendableto dust from the deterioration of such paint may exhibit symptoms. Levelsof environmental lead considered nontoxic may also be involved in change magnitudehypertension in a significant number of persons, according to studiesreleased in the mid-1980s. As a result, the U.S. Centers for Disease Controlin recent years birth been revising downward the levels of environmentallead that it would consider safe. At one time, lead poisoning was commonamong those who worked with lead, but such workplace hazards have been largely curtailed.Lead has been used by humans since ancient times.It was used in ancient Egypt in coins, weights,ornaments, utensils,ceramic glazes, and solder. Lead is mentioned in the Old Testament. TheRomansconveyed drinking water in lead pipes, some of which are still in operation.Roman slavesextracted and prepared the lead, describes a disease amongthe slaves that was clearly lead poisoning. Because of their potentialtoxicity, lead water pipes are no longer being installed. The greatestsingle use of lead metal today is in the plates of storage batteries forautomobiles.The protective oxidation bottom formed by lead in contactwith such substances as air, sulfuric acid,and fluorine makes it highlyresistant to corrosion. For this reason, lead has been used to makedrainpipepipes and lead chambers in sulfuric acid factories. It is also used asa roofing material. Thesoftness and malleability of lead make it effectivefor sheathing telephone and television cables. Lead isused in solderbecause of its low melting point. When combined with tin, lead forms solder