Jump to content

Lead: Difference between revisions

Edit links
From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
m Reverting possible vandalism by 151.213.140.58 to version by Edgar181. False positive? Report it. Thanks, ClueBot NG. (632918) (Bot)
Undid revision 454123122 by 151.213.140.58 (talk)
Line 1: Line 1:
{{About|the metal}}
{{infobox lead}}


GAY
'''Lead''' ({{IPAc-en|icon|ˈ|l|ɛ|d}}) is a main-group [[Chemical element|element]] in the [[carbon group]] with the symbol '''Pb''' (from {{lang-la|plumbum}}) and [[atomic number]] 82. Lead is a soft, [[malleable]] [[poor metal]]. It is also counted as one of the [[heavy metal (chemistry)|heavy metal]]s. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid.

Lead is used in building construction, [[lead-acid battery|lead-acid batteries]], [[bullet]]s and [[lead shot|shot]]s, weights, as part of [[solder]]s, [[pewter]]s, [[fusible alloy]]s and as a [[radiation shield]]. Lead has the highest [[atomic number]] of all of the [[stable element]]s, although the next higher element, [[bismuth]], has a [[half-life]] that is so long (much longer than the age of the universe) that it can be considered stable. Its four stable isotopes have 82 [[proton]]s, a [[magic number (physics)|magic number]] in the [[nuclear shell model]] of [[atomic nuclei]].

Lead, at certain exposure levels, is a poisonous substance to animals as well as for human beings. It damages the [[nervous system]] and causes [[brain]] disorders. Excessive lead also causes blood disorders in mammals. Like the element [[mercury (element)|mercury]], another heavy metal, lead is a [[neurotoxin]] that accumulates both in soft tissues and the bones. [[Lead poisoning]] has been documented from [[ancient Rome]], [[ancient Greece]], and [[ancient China]].

==Characteristics==
{{Expand section|date=January 2008}}
[[File:Lead-2.jpg|thumb|left|A sample of recently solidified lead (from a molten state)]]
Lead is bright and silvery when freshly cut but the surface rapidly tarnishes in air to produce the commonly observed dull luster normally associated with lead. It is a [[density|dense]], [[ductile]], very soft, highly malleable, bluish-white metal that has poor [[electrical conductivity]] when compared to most other metals. This metal is highly resistant to [[corrosion]], and because of this property, it is used to contain corrosive liquids (for example, [[sulfuric acid]]). Because lead is very malleable and resistant to corrosion it is extensively used in building construction – for example in the external coverings of roofing joints.

Metallic lead can be toughened by addition of small amounts of [[antimony]], or a small number of other metals such as [[calcium]]. All [[isotope]]s of lead, except for lead-204, can be found in the end products of the [[radioactive decay]] of the even heavier elements, [[uranium]] and [[thorium]].

Powdered lead burns with a bluish-white flame. As with many metals, finely divided powdered lead exhibits [[pyrophoricity]].<ref>{{cite journal|last1=Charles|first1=J.|last2=Kopf|first2=P. W.|last3=Toby|first3=S.|title=The Reaction of Pyrophoric Lead with Oxygen|journal=Journal of Physical Chemistry|volume=70|pages=1478|year=1966|doi=10.1021/j100877a023}}</ref> Toxic fumes are released when lead is burned.

==Isotopes==
{{Main|Isotopes of lead}}
Lead can be found or produced in many [[isotope]]s, with three of them being stable. The four natural isotopes of lead are <sup>204</sup>Pb, <sup>206</sup>Pb, <sup>207</sup>Pb, and <sup>208</sup>Pb with the slightly radioactive <sup>204</sup>Pb regarded as completely primordial lead, and the stable isotopes 206, 207, 208 being formed probably from the [[radioactive decay]] of two isotopes of uranium ([[Uranium-235|U-235]] and [[Uranium-238|U-238]]) and one isotope of [[thorium]] ([[Th 232]]).

The one common [[radiogenic isotope]] of lead, <sup>202</sup>Pb, has a [[half-life]] of about 53,000 years.<ref name="NUBASE">{{cite journal|first = Audi|last = Georges|title = The NUBASE Evaluation of Nuclear and Decay Properties|journal = Nuclear Physics A|volume = 729| pages = 3–128| publisher = Atomic Mass Data Center| year = 2003| doi = 10.1016/j.nuclphysa.2003.11.001| bibcode=2003NuPhA.729....3A}}</ref>

==Chemistry==

Various oxidized forms of lead are easily reduced to the metal. An example is heating PbO with mild organic reducing agents such as glucose. A mixture of the oxide and the sulfide heated together will also form the metal.<ref name="pauling">{{cite book|first = Pauling|last = Linus|title = General Chemistry|publisher = W.H. Freeman|year = 1947|isbn = 0486656225}}</ref>

: 2 PbO + PbS → 3 Pb + SO<sub>2</sub>

Metallic lead is attacked (oxidized) only superficially by air, forming a thin layer of lead oxide that protects it from further oxidation. The metal is not attacked by [[sulfuric acid|sulfuric]] or [[hydrochloric acid|hydrochloric]] acids. It dissolves in [[nitric acid]] with the evolution of [[nitric oxide]] gas to form dissolved [[lead(II) nitrate|Pb(NO<sub>3</sub>)<sub>2</sub>]].

: 3 Pb + 8 H<sup>+</sup> + 8 {{chem|NO|3|-}} → 3 Pb<sup>2+</sup> + 6 {{chem|NO|3|-}} + 2 NO + 4 H<sub>2</sub>O

When heated with [[nitrate]]s of alkali metals, metallic lead oxidizes to form [[lead(II) oxide|PbO]] (also known as [[litharge]]), leaving the corresponding alkali [[nitrite]]. PbO is representative of lead's +2 oxidation state. It is soluble in [[nitric acid|nitric]] and [[acetic acid|acetic]] acids, from which solutions it is possible to precipitate [[halide]], [[lead sulfate|sulfate]], [[lead chromate|chromate]], [[lead carbonate|carbonate]] (PbCO<sub>3</sub>), and basic carbonate ({{chem|Pb|3|(OH)|2|(CO|3|)|2|)}} salts of lead. The [[lead sulfide|sulfide]] can also be precipitated from [[lead acetate|acetate]] solutions. These salts are all poorly soluble in water. Among the halides, the iodide is less soluble than the bromide, which, in turn, is less soluble than the chloride.<ref name="brady_holum">{{cite book| last1 = Brady|first1= James E. |last2=Holum|first2=John R.|title = Descriptive Chemistry of the Elements| publisher = John Wiley and Sons| year = 1996| isbn = 0471135577}}</ref>

Lead(II) oxide is also soluble in [[alkali metal|alkali]] [[hydroxide]] solutions to form the corresponding [[plumbite]] salt.<ref name="pauling" />

: PbO + 2 OH<sup>−</sup> + H<sub>2</sub>O → {{chem|Pb(OH)|4|2-}}

[[Chlorination]] of plumbite solutions causes the formation of lead's +4 oxidation state.

: {{chem|Pb(OH)|4|2-}} + Cl<sub>2</sub> → PbO<sub>2</sub> + 2 Cl<sup>−</sup> + 2 H<sub>2</sub>O

[[Lead dioxide]] is representative of the +4 oxidation state, and is a powerful [[oxidizing agent]]. The chloride of this oxidation state is formed only with difficulty and decomposes readily into lead(II) chloride and chlorine gas. The bromide and iodide of lead(IV) are not known to exist.<ref name="brady_holum" /> Lead dioxide dissolves in alkali hydroxide solutions to form the corresponding [[plumbate]]s.<ref name="pauling" />

: PbO<sub>2</sub> + 2 OH<sup>−</sup> + 2 H<sub>2</sub>O → {{chem|Pb(OH)|6|2-}}

Lead also has an oxide with mixed +2 and +4 oxidation states, [[lead tetroxide|red lead]] ({{chem|Pb|3|O|4}}), also known as ''minium''.

Lead readily forms an equimolar alloy with [[sodium]] metal that reacts with [[alkyl halide]]s to form [[organometallic]] compounds of lead such as [[tetraethyllead]].<ref>{{cite book| title = Merck Index of Chemicals and Drugs, 9th ed., monograph 8393| last = Windholz|first= Martha| publisher = Merck|year = 1976|isbn = 0911910263}}</ref>

===Chloride complexes===
[[File:Lead complexes in chloride media.png|left|thumb|300px|Diagram showing the forms of lead in chloride media.<ref name="medusa">{{cite book|last=Puigdomenech|first=Ignasi |title=Hydra/Medusa Chemical Equilibrium Database and Plotting Software|year=2004|publisher=KTH Royal Institute of Technology|url=http://www.kemi.kth.se/medusa/}}</ref>]]

Lead(II) forms a series of complexes with [[chloride]], the formation of which alters the corrosion chemistry of the lead. This will tend to limit the solubility of lead in [[salinity|saline]] media.

{| class="wikitable"
|+ Equilibrium constants for aqueous lead chloride complexes at 25 °C<ref name="ward">{{cite book|title=Remediation of Firing Range Impact Berms|last1=Ward|first1= C. H.|last2= Hlousek|first2=Douglas A.|last3= Phillips|first3=Thomas A.|last4= Lowe|first4= Donald F.|isbn=1566704626|year=2000|publisher=CRC Press}}</ref>
|-
| Pb<sup>2+</sub> + Cl<sup>−</sup> → PbCl<sup>+</sup>
| ''K<sub>1</sub>'' = 12.59
|-
| PbCl<sup>+</sup> + Cl<sup>−</sup> → PbCl<sub>2</sub>
| ''K<sub>2</sub>'' = 14.45
|-
| PbCl<sub>2</sub> + Cl<sup>−</sup> → PbCl<sub>3</sub><sup>−</sup>
| ''K<sub>3</sub>'' = 3.98 ×10<sup>−1</sup>
|-
| PbCl<sub>3</sub><sup>−</sup> + Cl<sup>−</sup> → PbCl<sub>4</sub><sup>2−</sup>
| ''K<sub>4</sub>'' = 8.92 × 10<sup>−2</sup>
|}
{{-}}

===Phase diagrams of solubilities===
{{See also|Phase diagram}}
Lead(II) sulfate is poorly soluble, as can be seen in the following diagram showing addition of SO<sub>4</sub><sup>2−</sup> to a solution containing 0.1 M of Pb<sup>2+</sub>. The pH of the solution is 4.5, as above that, Pb<sup>2+</sup> concentration can never reach 0.1 M due to the formation of Pb(OH)<sub>2</sub>. Observe that Pb<sup>2+</sup> solubility drops 10,000 fold as SO<sub>4</sub><sup>2−</sup> reaches 0.1 M.

<br style="clear:both;"><center>
{| class="wikitable" style="text-align:center"
|-
| style="width:60%;"|[[File:PbSO4 solubility graph.png|420px]]
| style="width:40%;"|[[File:Lead sulphate pourdaix diagram.png|280px]]
|-
| Plot showing aqueous concentration of dissolved Pb<sup>2+</sub> as a function of SO<sub>4</sub><sup>2−</sup> <ref name="medusa"/>
|Diagram for lead in sulfate media<ref name="medusa"/>
|}
</center>

{{clear}}
The addition of chloride can lower the solubility of lead, though in chloride-rich media (such as [[aqua regia]]) the lead can become soluble again as anionic chloro-complexes.
<br style="clear:both;">
<center>
{| class="wikitable" style="text-align:center"
|-
| style="width:60%;"|[[File:PbCl2 solubility graph.png|420px]]
| style="width:40%;"|[[File:Lead chloride pourdiax diagram.png|280px]]
|-
| Diagram showing the solubility of lead in chloride media. The lead concentrations are plotted as a function of the total chloride present.<ref name="medusa"/>
|[[Pourbaix diagram]] for lead in chloride (0.1 M) media<ref name="medusa"/>
|}
</center>
{{clear}}

==History==
[[File:World Lead Production.jpg|thumb|left|World lead production peaking in the [[Ancient Rome|Roman]] period and the rising [[Industrial Revolution]]<ref name="Hong, Candelone, Patterson, Boutron 1994, 1841–1843"/>]]
[[File:Lead ingots.JPG|thumb|Lead [[ingot]]s from [[Roman Britain]] on display at the [[Wells and Mendip Museum]]]]
[[File:Lead mining Barber 1865p321cropped.jpg|thumb|Lead mining in the upper [[Mississippi River]] region of the U.S., 1865.]]

Lead has been commonly used for thousands of years because it is widespread, easy to extract and easy to work with. It is highly malleable and ductile as well as easy to [[smelting|smelt]]. Metallic lead beads dating back to 6400 BCE have been found in [[Çatalhöyük]] in modern-day Turkey.<ref>{{cite journal|title = A Model for the Adoption of Metallurgy in the Ancient Middle East|last = Heskel|first= Dennis L.|journal = Current Anthropology|volume = 24|issue = 3|year = 1983|pages = 362–366|doi = 10.1086/203007}}</ref> In the early [[Bronze Age]], lead was used with [[antimony]] and [[arsenic]].

The largest [[Industrial Revolution|preindustrial]] producer of lead was the [[Roman economy]], with an estimated output per annum of 80,000 [[Tonnes|t]], which was typically won as a by-product of extensive silver smelting.<ref name="Hong, Candelone, Patterson, Boutron 1994, 1841–1843">{{Cite journal|doi=10.1126/science.265.5180.1841|last1=Hong|first1=Sungmin|last2= Candelone|first2= Jean-Pierre|first3=Clair Cameron |last3=Patterson|last4= Boutron|first4= Claude F.|year=1994|title=Greenland Ice Evidence of Hemispheric Lead Pollution Two Millennia Ago by Greek and Roman Civilizations|journal=Science|volume= 265|issue=5180|pages=1841–1843|pmid=17797222|bibcode = 1994Sci...265.1841H }}</ref><ref name="Callataÿ 2005, 361–365">{{cite journal|last=Callataÿ|first= François de |year=2005|title=The Graeco-Roman Economy in the Super Long-Run: Lead, Copper, and Shipwrecks|journal=Journal of Roman Archaeology|volume=18|pages=361–372}} see pages 361–365.</ref><ref name="Settle, Patterson 1980, 1170f.">{{cite journal|doi=10.1126/science.6986654|last1=Settle|first1= Dorothy M.|last2= Patterson|first2=Clair C. |year=1980|title=Lead in Albacore: Guide to Lead Pollution in Americans|journal=Science|volume= 207|issue=4436|pages= 1167–1176|pmid=6986654|bibcode = 1980Sci...207.1167S }} see 1170f.</ref> [[Roman metallurgy|Roman mining activities]] occurred in [[Central Europe]], [[Roman Britain]], the [[Balkans]], [[Greece]], [[Asia Minor]]; [[Hispania]] alone accounted for 40% of world production.<ref name="Hong, Candelone, Patterson, Boutron 1994, 1841–1843"/>

Roman lead pipes often bore the insignia of Roman emperors (see [[Roman lead pipe inscription]]s). Lead plumbing in the [[Latin West]] may have been continued beyond the age of [[Theoderic the Great]] into the medieval period.<ref>{{cite book|isbn = 9789004106802|pages =134f.|editor=Squatriti, Paolo|year = 2000|publisher = Brill|location = Leiden|title = Working with water in medieval Europe : technology and resource use}}</ref> Many Roman "pigs" (ingots) of lead figure in [[Derbyshire lead mining history]] and in the history of the industry in other English centers. The Romans also used lead in molten form to secure iron pins that held together large [[limestone]] blocks in certain monumental buildings. In [[alchemy]], lead was thought to be the oldest metal and was associated with the planet [[Saturn]]. Alchemists accordingly used Saturn's symbol (the scythe, {{Unicode|♄}}) to refer to lead.

Lead's symbol Pb is an abbreviation of its [[Latin]] name ''plumbum'' for soft metals; originally it was ''plumbum nigrum'' (literally, "black ''plumbum''"), where ''plumbum candidum'' (literally, "bright ''plumbum''") was [[tin]]. The English words "[[plumbing]]", "[[plumber]]", "plumb", and "[[plumb-bob]]" also derive from this Latin root.

==Occurrence==

[[File:MV-Type and clastic sediment-hosted lead-zinc deposits.svg|thumb|right|Lead and zinc bearing carbonate and clastic deposits. Source: USGS]]
Metallic lead does occur in nature, but it is rare. Lead is usually found in [[ore]] with [[zinc]], [[silver]] and (most abundantly) [[copper]], and is extracted together with these metals. The main lead [[mineral]] is [[galena]] (PbS), which contains 86.6% lead. Other common varieties are [[cerussite]] (PbCO<sub>3</sub>) and [[anglesite]] (PbSO<sub>4</sub>).

===Ore processing===
[[File:Calcite-Galena-elm56c.jpg|thumb|left|upright|[[Galena]], lead ore]]

Most ores contain less than 10% lead, and ores containing as little as 3% lead can be economically exploited. Ores are crushed and concentrated by [[froth flotation]] typically to 70% or more. [[Sulfide]] ores are [[Roasting (metallurgy)|roasted]], producing primarily lead oxide and a mixture of [[sulfates]] and [[silicates]] of lead and other metals contained in the ore.<ref name="samans">{{cite book|last = Samans|first = Carl H.|title = Engineering Metals and their Alloys|publisher = MacMillan|year = 1949}}</ref>

Lead oxide from the roasting process is reduced in a coke-fired [[blast furnace]].<ref name="leadorg1">{{cite web|url = http://www.ldaint.org/technotes1.htm|title = Primary Extraction of Lead Technical Notes|publisher = LDA International|accessdate = 7 April 2007 |archiveurl = http://web.archive.org/web/20070322231927/http://www.ldaint.org/technotes1.htm <!-- Bot retrieved archive --> |archivedate = 22 March 2007}}</ref> This converts most of the lead to its metallic form. Three additional layers separate in the process and float to the top of the metallic lead. These are [[slag]] (silicates containing 1.5% lead), [[matte (metallurgy)|matte]] (sulfides containing 15% lead), and [[speiss]] (arsenides of iron and copper). These wastes contain concentrations of copper, zinc, cadmium, and bismuth that can be recovered economically, as can their content of unreduced lead.<ref name="samans"/>

Metallic lead that results from the roasting and blast furnace processes still contains significant contaminants of arsenic, antimony, bismuth, zinc, copper, silver, and gold. The melt is treated in a [[reverberatory furnace]] with air, steam, and sulfur, which oxidizes the contaminants except silver, gold, and bismuth. The oxidized contaminants are removed by [[dross]]ing, where they float to the top and are skimmed off.<ref name="samans"/><ref name="leadorg">{{cite web|url = http://www.ldaint.org/technotes2.htm|title = Primary Lead Refining Technical Notes|publisher = LDA International|accessdate = 7 April 2007 |archiveurl = http://web.archive.org/web/20070322191856/http://www.ldaint.org/technotes2.htm <!-- Bot retrieved archive --> |archivedate = 22 March 2007}}</ref>

Most lead ores contain significant concentrations of [[silver]], resulting in the smelted metal also containing silver as a contaminant. Metallic silver as well as gold is removed and recovered economically by means of the [[Parkes process]].<ref name="pauling"/><ref name="samans"/><ref name="leadorg"/>

Desilvered lead is freed of [[bismuth]] according to the [[Betterton-Kroll process]] by treating it with metallic calcium and magnesium, which forms a bismuth dross that can be skimmed off.<ref name="samans"/><ref name="leadorg"/>

Very pure lead can be obtained by processing smelted lead electrolytically by means of the [[Betts electrolytic process|Betts process]]. The process uses anodes of impure lead and cathodes of pure lead in an electrolyte of silica fluoride.<ref name="samans"/><ref name="leadorg"/>

===Production and recycling===
Production and consumption of lead is increasing worldwide. Total annual production is about 8&nbsp;million tonnes; about half is produced from recycled scrap. The top lead producing countries, as of 2008, are Australia, China, USA, Peru, Canada, Mexico, Sweden, Morocco, South Africa and North Korea.<ref name="infomin">{{cite web|url = http://www.infomine.com/commodities/lead.asp|title = Global InfoMine{{ndash}} Lead Mining|publisher = GlobalInfoMine |accessdate = 17 April 2008}}</ref> Australia, China and the United States account for more than half of primary production.<ref name="ldaint">{{cite web|url = http://www.ldaint.org/information.htm|title = Lead Information|publisher = LDA International|accessdate = 2007-09-05 |archiveurl = http://web.archive.org/web/20070827030846/http://www.ldaint.org/information.htm|archivedate = 2007-08-27}}</ref>

{{As of|2010|alt=In 2010}}, 9.6 million pounds of lead were produced, of which 4.1 million pounds came from mining.<ref name="ilzsg">"Mine Production: 4,117, 000 lbs; Metal Production: 9,604,000 lbs; Metal Usage: 9,569,000 lbs" from {{cite web|url=http://www.ilzsg.org/static/statistics.aspx|title = Lead and Zinc Statistics|publisher = International Lead and Zinc Study Group|accessdate = 2011-09-26}} (See also their [http://www.ilzsg.org/static/generaldef.aspx definitions of terms].)</ref>

At current use rates, the supply of lead is estimated to run out in 42 years.<ref>{{cite journal|date = May 26, 2007|journal = New Scientist|volume = 194|issue = 2605|pages = 38–39|issn = 0262-4079|title = How Long Will it Last?|bibcode = 2007NewSc.194...38R |doi = 10.1016/S0262-4079(07)61508-5 }}</ref> Environmental analyst [[Lester Brown]] has suggested lead could run out within 18 years based on an extrapolation of 2% growth per year.<ref name="Brown">{{cite book|last = Brown|first = Lester|title=Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble|publisher = New York: W.W. Norton|year = 2006 |page = 109|isbn = 0393328317}}</ref> This may need to be reviewed to take account of renewed interest in [[recycling]], and rapid progress in [[fuel cell]] technology. According to the [[International Resource Panel]]'s [[Metal Stocks in Society report]], the global per capita stock of lead in use in society is 8kg. Much of this is in more-developed countries (20–150kg per capita) rather than less-developed countries (1–4kg per capita).

==Applications==
Due to its [[half-life]] of 22.2 years, the radioactive isotope [[Isotopes of lead|<sup>210</sup>Pb]] is used for dating material from marine [[sediment]] cores by [[radiometric dating|radiometric]] methods.

===Elemental lead===
[[File:Lead shielding.jpg|thumb|Lead bricks are commonly used as radiation shielding.]]
Because of its high density and resistance from corrosion, lead is used for the [[Sailing ballast|ballast]] keel of sailboats. Its high density allows it to counterbalance the heeling effect of wind on the sails while at the same time occupying a small volume and thus offering the least underwater resistance. For the same reason it is used in [[scuba diving]] [[diving weighting system|weight belts]] to counteract the diver's natural buoyancy and that of his equipment. It does not have the weight-to-volume ratio of many heavy metals, but its low cost increases its use in these and other applications.

[[File:DSC00125 - Tubi di piombo romani - Foto di G. Dall'Orto.jpg|thumb|Roman lead water pipes with taps]]
[[File:Lead pipe Bath.jpg|thumb|Lead pipe in Roman baths]]
[[File:Lead glazed ceramic cup Tang China 8th century.jpg|thumb|Multicolor lead-glazing in a ''[[sancai]]'' ceramic cup, [[Tang dynasty]], [[China]], 8th century CE.]]

Lead is used in applications where its low melting point, ductility and high density is an advantage. The low melting point makes casting of lead easy, and therefore small arms ammunition and shotgun pellets can be cast with minimal technical equipment. It is also inexpensive and denser than other common metals.<ref>{{cite web|url = http://www.lead.org.au/fs/shootingranges.pdf|format = PDF|title = Contamination at Shooting Ranges|first = Corinne|last = Rooney|publisher = The Lead Group, incorporated|accessdate=7 April 2007}}</ref> The [[hot metal typesetting]] uses a lead based alloy to produce the types for printing directly before printing.

Its corrosion resistance makes it suitable for outdoor applications when in contact with water.

More than half of the worldwide lead production (at least 1.15 million metric tons) is used for automobiles, mostly as electrodes in the [[lead-acid battery]], used extensively as a [[car battery]].<ref>Ecology Center "Getting the Lead Out: Impacts of and Alternatives For Automotive Lead Uses"[http://www.ecocenter.org/sites/default/files/publications/docs/GettingLeadOut.pdf]</ref>

[[Cathode]] ([[redox|reduction]])
:PbO<sub>2</sub> + 4 H<sup>+</sup> + SO<sub>4</sub><sup>2–</sup> + 2e<sup>–</sup> → PbSO<sub>4</sub> + 2 H<sub>2</sub>O
[[Anode]] ([[oxidation]])
:Pb + SO<sub>4</sub><sup>2–</sup> → PbSO<sub>4</sub> + 2e<sup>–</sup><ref>{{cite book|url = http://books.google.com/?id=q58IX4BM7-0C&pg=PT210|isbn = 9780750646253|pages = 18/2–18/4|first = T.R.|last= Crompton.|year = 2000|publisher = Newnes|location = Oxford, England|title = Battery reference book}}</ref><ref>{{cite book|title = Encyclopaedia of Occupational Health and Safety|first = Jeanne Mager|last = Stellman|publisher = International Labour Organization|year = 1998|isbn = 9789221098164|pages = 81.2–81.4|url = http://books.google.com/?id=nDhpLa1rl44C&pg=PT644}}</ref>

Lead is used as [[electrodes]] in the process of [[electrolysis]]. Lead is used in [[solder]] for electronics, although this usage is being phased out by some countries to reduce the amount of [[Environmental hazard|environmentally hazardous]] waste. Lead is used in high voltage power cables as sheathing material to prevent water diffusion into insulation.

Lead is one of three metals used in the [[Oddy test]] for museum materials, helping detect organic acids, aldehydes, and acidic gases.

Lead is used as [[lead shielding|shielding]] from [[Ionizing radiation|radiation]] (e.g., in [[X-ray]] rooms).<ref>{{cite book|url = http://books.google.com/?id=DKu4YDjEluoC&pg=PA16|isbn = 9780929600833|pages = 16–17|year = 2004|publisher = National Council on Radiation Protection and Measurement|location = Bethesda, MD|title = Structural shielding design for medical X-ray imaging facilities.}}</ref> Molten lead is used as a [[coolant]] (e.g., for [[lead cooled fast reactor]]s).<ref>{{cite journal|doi = 10.1016/j.nucengdes.2006.04.019|url = http://www.ecolo.org/documents/documents_in_english/SFRvsLFR-05.pdf|title = Comparison of sodium and lead-cooled fast reactors regarding reactor physics aspects, severe safety and economical issues|year = 2006|last = Tuček|first= Kamil|journal = Nuclear Engineering and Design|volume = 236|page = 1589|last2 = Carlsson|first2 = Johan|last3 = Wider|first3 = Hartmut}}</ref><!-- isbn = 9783527406791|page = 271-->

Lead is added to [[brass]] to reduce [[machine tool]] wear.
Lead, in the form of strips, or tape, is used for the customization of tennis rackets. Tennis rackets of the past sometimes had lead added to them by the manufacturer to increase weight.<ref>{{cite book|url = http://books.google.com/?id=p7Ne5IjK5H0C&pg=PA250|isbn = 9780415408813|page = 250|title = Routledge Handbook of Biomechanics and Human Movement Science|editor= Hong, Youlian and Bartlett, Roger|year = 2008|publisher = Routledge|location = London}}</ref>

Lead is used to form glazing bars for [[stained glass]] or other multi-lit windows. The practice has become less common, not for danger but for stylistic reasons.<!-- http://www.bmj.com/cgi/reprint/291/6492/383 10.1136/bmj.291.6492.383 G Frenzel – Scientific American, 1985 – archaeometry.dk http://www.archaeometry.dk/Glas/The%20Restoration%20of%20Medieval%20Stained%20Glass.pdf
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1567791 The cultural parameters of lead poisoning: a medical anthropologist's view of intervention in environmental lead exposure.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1512529 Dishware as a a possible source of lead poisoning
10.1016/S0026-265X(02)00100-5 Characterization of lead and lead leaching properties of lead glazed ceramics from the Solis Valley, Mexico
10.1006/jasc.1996.0085 Roman Glazed Ceramics in the Western Mediterranean:
-->
Lead, or ''sheet-lead'', is used as a sound deadening layer in some areas in wall, floor and ceiling design in sound studios where levels of airborne and mechanically produced sound are targeted for reduction or virtual elimination.<ref>{{cite book|url =http://books.google.com/?id=gDwOAAAAQAAJ&pg=PA31|isbn = 9780824782474|page = 31|last =Guruswamy|first=Sivaraman|year =2000|publisher =Marcel Dekker|location =New York, NY|title =Engineering properties and applications of lead alloys}}</ref><ref>{{cite book|url = http://books.google.com/?id=TtGmjOv9CUAC&pg=PA240|isbn = 9780709916536|page = 240|editor=Lansdown, Richard and Yule, William|year = 1986|publisher = Croom Helm|location = London|title = The Lead debate : the environment, toxicology, and child health}}</ref>

Lead is the traditional base metal of [[organ pipe]]s, mixed with varying amounts of [[tin]] to control the tone of the pipe.<ref>{{cite book|url = http://books.google.com/?id=I0h525OVoTgC&pg=PA503|isbn = 9780486213156|pages = 250–251|title = The Art of Organ Building|last = Audsley|first=George Ashdown|date = 1988-04-01|volume=2}}</ref><ref>{{cite book|url = http://books.google.com/?id=cgDJaeFFUPoC&pg=PA412|pages = 412–413|title = The Organ|isbn = 9780415941747|editor = Palmieri, Robert|year = 2006|publisher = Garland|location = New York u.a.}}</ref>

Lead has many uses in the construction industry (e.g., lead sheets are used as [[architectural metals]] in roofing material, cladding, flashing, gutters and gutter joints, and on roof parapets). Detailed lead moldings are used as decorative motifs used to fix lead sheet. Lead is still widely used in statues and sculptures.
Lead is often used to [[tire balance|balance]] the wheels of a car; this use is being phased out in favor of other materials for environmental reasons.

===Lead compounds===
Lead compounds are used as a coloring element in [[ceramic glaze]]s, notably in the colors red and yellow.<ref>{{cite journal|journal = Calif. Med.|year = 1958|volume = 89|issue = 6|pages = 414–416|pmc = 1512529|title = Dishware as a Possible Source for Lead Poisoning|first1 =Alvin R.|last1 = Leonard|last2 = Lynch|first2= Glenn|pmid = 13608300}}</ref><!-- http://books.google.com/books?id=aE_VQ8I24OoC&pg=PA20

http://books.google.com/books?id=PiJEAhMxLQgC&pg=PA23
http://jama.ama-assn.org/cgi/content/citation/202/6/544
10.1007/BF00542755
-->
Lead is frequently used in [[polyvinyl chloride]] (PVC) plastic, which coats electrical cords.<ref>{{cite book|url = http://books.google.com/?id=WbBH5QFXOhoC&pg=PT475|page = 438|isbn = 9783446408012 |title =Plastics Additives Handbook|first = Hans|last = Zweifel|publisher = Hanser Verlag|year = 2009}}</ref><ref>{{cite book|url = http://books.google.com/?id=YUkJNI9QYsUC&pg=PA106|page = 106| isbn = 9781569903797|last1 = Wilkes|first1= C. E.|last2=Summers|first2= J. W.|last3= Daniels|first3=C. A.|last4= Berard|first4=M. T.|year = 2005|publisher = Hanser|location = München|title = PVC handbook}}</ref>
<!-- Basic lead sulfate, basic lead phthalate and basic lead phosphate are used as stabilizer for [[polyvinyl chloride]] (PVC) plastic. The lead oxide in the compounds improves the heat stability by reacting with hydrochloride and adding to double bonds in the structure of the PVC, which are starting points for degradation of the polymer. While in Europe PVC for the use in windows and pipes also uses lead based stabilizers in the US most of the lead stabilized PVC is used for coats of electrical cords.-->

Lead is used in some candles to treat the wick to ensure a longer, more even burn. Because of the dangers, European and North American manufacturers use more expensive alternatives such as zinc.<ref>{{cite journal|url = http://www.newscientist.com/article/mg17423481.900-candle-pollution.html|journal = NewScientist.com|title = Candle pollution|first = James|last = Randerson|month = June|year = 2002|accessdate = 2007-04-07| issue = 2348}}</ref><ref>{{cite journal|doi = 10.1016/S0048-9697(00)00359-4|title = Emissions of lead and zinc from candles with metal-core wicks|year = 2000|last = Nriagu|first= J|journal = The Science of the Total Environment|volume = 250|page = 37|pmid = 10811249|last2 = Kim|first2 = MJ|issue = 1–3}}</ref> [[Lead glass]] is composed of 12–28% [[Lead(II) oxide|lead oxide]]. It changes the optical characteristics of the glass and reduces the transmission of radiation.<ref>{{cite book|isbn = 9780070016194| publisher = McGraw-Hill Professional|year = 1997|first = Joseph S.|last = Amstock|title = Handbook of glass in construction|url = http://books.google.com/?id=apWvKnKKrvsC&pg=PA116 |pages = 116–119}}</ref>

Some artists using oil-based paints continue to use lead carbonate white, citing its properties in comparison with the alternatives. Tetra-ethyl lead is used as an anti-knock additive for aviation fuel in piston-driven aircraft. Lead-based [[semiconductors]], such as [[lead telluride]], [[lead selenide]] and [[lead antimonide]] are finding applications in [[photovoltaic]] (solar energy) cells and [[infrared]] detectors.<ref name="Applications for Lead">{{cite web|url = http://www.americanelements.com/pb.html|title = Applications for Lead|accessdate = 7 April 2007}}</ref>

===Former applications===
Lead pigments were used in [[lead paint]] for white as well as [[chrome yellow|yellow]], orange, and [[chrome red|red]]. Most uses have been discontinued due of the dangers of lead poisoning. Beginning April 22, 2010, US federal law requires that contractors performing renovation, repair, and painting projects that disturb more than six square feet of paint in homes, child care facilities, and schools built before 1978 must be certified and trained to follow specific work practices to prevent lead contamination. [[Lead chromate]] is still in industrial use. Lead carbonate (white) is the traditional pigment for the priming medium for oil painting, but it has been largely displaced by the zinc and titanium oxide pigments. It was also quickly replaced in water-based painting mediums. Lead carbonate white was used by the Japanese [[geisha]] and in the West for face-whitening make-up, which was detrimental to health.

Lead was the hot metal used in [[hot metal typesetting]]. It was used for [[plumbing]] as well as a [[Food preservation|preservative]] for food and drink in [[Ancient Rome]]. Until the early 1970s, lead was used for joining cast iron water pipes and used as a material for small diameter water pipes.

[[Tetraethyllead]] was used in [[Gasoline#Lead|leaded fuel]]s to reduce [[engine knocking]], but this practice has been phased out across many countries of the world in efforts to reduce toxic pollution that affected humans and the environment.<ref>{{cite web|url=http://www.dft.gov.uk/pgr/roads/environment/lrp/leadreplacementpetrolphaseout|title=Lead replacement petrol phase-out – Information to motorists|publisher=Department for Transport (gov.uk)}}</ref><ref>{{cite web|url=http://www.environment.gov.au/atmosphere/airquality/publications/qa.html|title=National phase out of leaded petrol: Some questions and answers|publisher=Department of the Environment and Heritage, Australian Government|year=2001}}</ref><ref name="Banning of Leaded Gasoline for Highway Use">{{cite news|url=http://www.accessmylibrary.com/coms2/summary_0286-6346110_ITM|title=Banning of Leaded Gasoline for Highway Use|accessdate=23 September 2008|work=Knight Ridder/Tribune Business News|date=4 October 1995}}</ref>

Lead was used to make bullets for [[sling (weapon)|slings]]. Lead was used for [[shotgun]] pellets in the US until about 1992 when it was outlawed (for [[waterfowl]] hunting only) and replaced by [[non-toxic]] shot, primarily steel pellets. In the [[Netherlands]], the use of lead shot for hunting and sport shooting was banned in 1993, which caused a large drop in lead emission, from 230 ton in 1990 to 47.5 ton in 1995, two years after the ban.<ref>{{ cite web|url = http://www.emissieregistratie.nl/ERPUBLIEK/documenten/Water/Factsheets/Nederlands/Lood-%20en%20zinkemissies%20door%20jacht.pdf|language=Dutch|format=PDF|title=Lood en zinkemissies door jacht|date=April 2010}}</ref>

Lead was a component of the paint used on children's toys – now restricted in the United States and across Europe ([[ROHS Directive]]). Lead was used in car body filler, which was used in many [[custom car]]s in the 1940s–60s. Hence the term [[Leadsled]]. Lead is a [[superconductor]] at 7.2&nbsp;K and [[IBM]] tried to make a [[Josephson effect]] computer out of lead-alloy.<ref>{{cite web|url = http://adsabs.harvard.edu/abs/1985JAP....58.2371H|title = Josephson 4 K-bit cache memory design for a prototype signal processor|last1=Henkels|first1=W. H.|last2= Geppert|first2= L. M.|last3= Kadlec|first3= J.|last4= Epperlein|first4= P. W.|last5= Beha|first5= H.|accessdate = 7 April 2007|month = September|year=1985| publisher = Harvard University}}</ref>

Lead was also used in pesticides before the 1950s, when fruit orchards were treated ([[ATSDR]]). A lead cylinder attached to a long line was used by sailors for the vital navigational task of determining water depth by ''heaving the lead'' at regular internals. A soft tallow insert at its base allowed the nature of the sea bed to be determined, further aiding position finding. Contrary to popular belief, pencil leads in wooden pencils have never been made from lead. The term comes from the Roman stylus, called the ''penicillus'', which was made of lead without a wooden holder.<ref>{{cite web|url = http://www.pencils.com/history.html|title = A history of pencils|accessdate= 7 April 2007|publisher = www.pencils.com}}</ref> When the pencil originated as a wrapped graphite writing tool, the particular type of [[graphite]] being used was named [[Plumbago_(mineral)#Plumbago|''plumbago'']] (lit. ''act for lead'', or ''lead mockup'').

==Health effects==
{{Main|Lead poisoning}}
Lead is a poisonous metal that can damage nervous connections (especially in young children) and cause blood and brain disorders. Lead poisoning typically results from ingestion of food or water contaminated with lead; but may also occur after accidental ingestion of contaminated soil, dust, or lead based paint.<ref>{{cite web|publisher=Agency for Toxic Substances and Disease Registry/Division of Toxicology and Environmental Medicine|year=2006|title=ToxFAQs: CABS/Chemical Agent Briefing Sheet: Lead.|url=http://www.atsdr.cdc.gov/cabs/lead/lead_cabs.pdf}}</ref> Long-term exposure to lead or its salts (especially soluble salts or the strong oxidant PbO<sub>2</sub>) can cause [[nephropathy]], and [[colic]]-like abdominal pains. The effects of lead are the same whether it enters the body through breathing or swallowing. Lead can affect almost every organ and system in the body. The main target for lead toxicity is the nervous system, both in adults and children. Long-term exposure of adults can result in decreased performance in some tests that measure functions of the nervous system. It may also cause weakness in fingers, wrists, or ankles. Lead exposure also causes small increases in blood pressure, particularly in middle-aged and older people and can cause anemia. Exposure to high lead levels can severely damage the brain and kidneys in adults or children and ultimately cause death. In pregnant women, high levels of exposure to lead may cause miscarriage. Chronic, high-level exposure have shown to reduce fertility in males.<ref>{{cite book|isbn = 9780415700405|url = http://books.google.com/?id=Qt8LEB7_HyQC&pg=PA153|page = 153|chapter = Summary|editor = Golub, Mari S.| year = 2005|publisher = Taylor and Francis|location = Boca Raton, Fla.|title = Metals, fertility, and reproductive toxicity}}</ref> The antidote/treatment for lead poisoning consists of [[dimercaprol]] and [[succimer]].

{| class="wikitable" align=right
|-
! style="background:#f90;"|NFPA 704
|-
| style="text-align:left;"|{{NFPA 704|Health = 3|Flammability = 1|Reactivity = 0|Other =}}
|-
| style="width:80pt;"|Fire diamond for lead granules
|}

The concern about lead's role in cognitive deficits in children has brought about widespread reduction in its use (lead exposure has been linked to [[learning disabilities]]).<ref>{{cite journal|last =Hu|first = Howard|title = Knowledge of diagnosis and reproductive history among survivors of childhood plumbism|journal = [[American Journal of Public Health]]|year = 1991|volume = 81|issue = 8|pages = 1070–1072|pmid = 1854006|doi = 10.2105/AJPH.81.8.1070|pmc = 1405695}}</ref> Most cases of adult elevated blood lead levels are workplace-related.<ref>{{cite web|url= http://www.cdc.gov/niosh/topics/ABLES/ables-description.html|title= NIOSH Adult Blood Lead Epidemiology and Surveillance|accessdate=2007-10-04| publisher = United States National Institute for Occupational Safety and Health}}</ref> High blood levels are associated with delayed puberty in girls.<ref>{{cite journal|last1 = Schoeters|first1 = Greet|last2 = Den Hond|first2 = Elly|last3 = Dhooge|first3 = Willem|last4 = Van Larebeke|first4 = Nik|last5 = Leijs|first5 = Marike|title = Endocrine Disruptors and Abnormalities of Pubertal Development|journal = Basic & Clinical Pharmacology & Toxicology|volume = 102|pages = 168–175|year = 2008|pmid=18226071|issue = 2|doi = 10.1111/j.1742-7843.2007.00180.x}}</ref> Lead has been shown many times to permanently reduce the cognitive capacity of children at extremely low levels of exposure.<ref>{{cite journal|doi = 10.1056/NEJM199001113220203|journal= New England Journal of Medicine|year = 1990|last1 = Needleman|volume = 322|issue = 2|first1 = Herbert L.|pages = 83–88|last2 = Schell|pmid = 2294437|first2 = Alan|last3 = Bellinger|first3 = David|last4 = Leviton|first4 = Alan|last5 = Allred|first5 = Elizabeth N.|title = The long-term effects of exposure to low doses of lead in childhood. An 11-year follow-up report|url = http://content.nejm.org/cgi/content/abstract/322/2/83}}</ref>

During the 20th century, the use of lead in paint [[pigment]]s was sharply reduced because of the danger of lead poisoning, especially to children.<ref>{{cite web|url = http://www.derm.qld.gov.au/heritage/owning_a_heritage_place/general_exemptions/g1__maintenance_and_minor_repair/lead_paint_cautionary_note.html|title = Download: Lead paint: Cautionary note|accessdate = 7 April 2007|publisher=Queensland Government}}</ref><ref>{{cite web|url=http://www.qld.mpa.org.au/index.php/content/33/|title = Lead Paint Information|accessdate=7 April 2007|publisher = Master Painters, Australia}}</ref> By the mid-1980s, a significant shift in lead end-use patterns had taken place. Much of this shift was a result of the U.S. lead consumers' compliance with environmental regulations that significantly reduced or eliminated the use of lead in non-battery products, including [[gasoline]], paints, solders, and water systems. Lead use is being further curtailed by the European Union's [[Restriction of Hazardous Substances Directive|RoHS directive]]. Lead may still be found in harmful quantities in stoneware, vinyl (such as that used for tubing and the insulation of electrical cords), and brass manufactured in China. Between 2006 and 2007 many children's toys made in China were recalled, primarily due to lead in paint used to color the product.

Older houses may still contain substantial amounts of [[lead paint]]. White lead paint has been withdrawn from sale in industrialized countries, but the yellow [[lead chromate]] is still in use; for example, [[Holland Colours]] Holcolan Yellow. Old paint should not be stripped by sanding, as this produces inhalable dust.

Lead salts used in pottery glazes have on occasion caused poisoning, when acidic drinks, such as fruit juices, have leached lead ions out of the glaze.<ref>{{cite web|url= http://www.fda.gov/ICECI/ComplianceManuals/CompliancePolicyGuidanceManual/ucm074516.htm|title = CPG Sec. 545.450 Pottery (Ceramics); Import and Domestic – Lead Contamination|accessdate = 2010-02-02|publisher=U.S. Food and Drug Administration}}</ref> It has been suggested that what was known as "[[Devon colic]]" arose from the use of lead-lined presses to extract apple juice in the manufacture of [[cider]]. Lead is considered to be particularly harmful for women's ability to reproduce. <!--For that reason, many universities do not hand out lead-containing samples to women for instructional laboratory analyses.--> [[Lead(II) acetate]] (also known as ''sugar of lead'') was used by the [[Roman Empire]] as a sweetener for wine, and some consider this to be the cause of the [[dementia]] that affected many of the Roman Emperors.<ref>{{cite news|date=August 21, 2007|url=http://www.nytimes.com/2007/08/21/science/21angi.html?_r=1&oref=slogin|title = The Pernicious Allure of Lead|publisher = New York Times|first=Natalie|last=Angier|accessdate=7 May 2010}}</ref>

Lead as a [[soil contaminant]] is a widespread issue, since lead is present in natural deposits and may also enter soil through (leaded) gasoline leaks from [[underground storage tank]]s or through a wastestream of lead paint or lead grindings from certain industrial operations.

Lead can also be found listed as a [[criteria pollutant]] in the [[United States Clean Air Act]] section 108. Lead that is emitted into the atmosphere can be inhaled, or it can be ingested after it settles out of the air. It is rapidly absorbed into the bloodstream and is believed to have adverse effects on the central nervous system, the cardiovascular system, kidneys, and the immune system.<ref>{{cite journal |doi=10.1002/tqem.20197 |title=The proposed lead NAAQS: Is consideration of cost in the clean air act's future? |year=2008 |last=Bergeson|first= Lynn L. |journal=Environmental Quality Management |volume=18 |page=79}}</ref>

===Biochemistry of lead poisoning===
In the human body, lead inhibits [[porphobilinogen synthase]] and [[ferrochelatase]], preventing both [[porphobilinogen]] formation and the incorporation of [[iron]] into [[protoporphyrin IX]], the final step in [[heme]] synthesis. This causes ineffective heme synthesis and subsequent [[microcytic anemia]].<ref>{{cite journal|url = http://pediatrics.aappublications.org/cgi/content/abstract/67/6/904|title = Reassessment of the Microcytic Anemia of Lead Poisoning|first1 = Alan R.|last1 = Cohen|first2 = Margret S.|last2 = Trotzky|first3 = Diane|last3= Pincus|journal = Pediatrics|volume = 67|issue = 6
|year = 1981|pages = 904–906|pmid = 7232054 }}</ref> At lower levels, it acts as a calcium analog, interfering with ion channels during nerve conduction. This is one of the mechanisms by which it interferes with cognition. Acute lead poisoning is treated using disodium calcium edetate: the calcium [[chelate]] of the disodium salt of ethylene-diamine-tetracetic acid ([[EDTA]]). This chelating agent has a greater affinity for lead than for calcium and so the lead chelate is formed by exchange. This is then excreted in the urine leaving behind harmless calcium.<ref>{{cite book| last = Laurence|first= D. R.|year = 1966| title = Clinical Pharmacology(Third Edition)}}</ref>

===Leaching of lead from metal surfaces===
The [[Pourbaix diagram]] below shows that lead is more likely to corrode in a citrate medium than it is in a non-complexing medium. The central part of the diagram shows that lead metal oxidizes more easily in the citrate medium than in normal water.

<center>
{| class="wikitable" style="float:right;margin-left:1em;text-align:center;"
|-
| style="width:50%;"|[[File:Pb in water Pourbiax diagram.png|350px]]
| style="width:50%;"|[[File:Pb in citrate media pourbiax diagram.png|360px]]
|-
| The Pourbaix diagram for lead in a non-complexing aqueous medium (e.g., [[perchloric acid]]/sodium hydroxide)<ref name="medusa"/>
|The [[Pourbaix diagram]] for lead in citric acid/citrate<ref name="medusa"/>
|}
</center>

In a Pourbaix diagram, the acidity is plotted on the x axis using the pH scale, while how oxidizing/reducing nature of the system is plotted on the y axis in terms of volts relative to the [[standard hydrogen electrode]]. The diagram shows the form of the element which is most chemically stable at each point, it only comments on [[thermodynamics]] and it says nothing about the rate of change ([[Chemical kinetics|kinetics]]).

===Exposure pathways===
Exposure to lead and lead chemicals can occur through inhalation, ingestion and dermal contact. Most exposure occurs through ingestion or inhalation; in the U.S. the skin exposure is unlikely as leaded gasoline additives are no longer used. Lead exposure is a global issue as lead mining and lead smelting are common in many countries. Most countries have stopped using lead-containing gasoline by 2007.<ref name=health>{{cite web|url=http://www.atsdr.cdc.gov/csem/lead/pbroute_exposure2.html |title=Case Studies in Environmental Medicine Lead (Pb) Toxicity: How are People Exposed to Lead?}}</ref>

Lead exposure mostly occurs through ingestion. Lead paint is the major source of lead exposure for children. As lead paint deteriorates, it peels, is pulverized into dust and then enters the body through hand-to-mouth contact or through contaminated food, water or alcohol. Ingesting certain home remedy medicines may also expose people to lead or lead compounds.<ref name=health/> Lead can be ingested through fruits and vegetables contaminated by high levels of lead in the soils they were grown in. Soil is contaminated through particulate accumulation from lead in pipes, lead paint and residual emissions from leaded gasoline that was used before the Environment Protection Agency issue the regulation around 1980.<ref>{{cite web|url=http://www.atsdr.cdc.gov/csem/lead/community/index.html|title=Information for the Community Lead Toxicity|publisher=Agency for Toxic Substances and Disease Registry}}</ref>

Inhalation is the second major pathway of exposure, especially for workers in lead-related occupations. Almost all inhaled lead is absorbed into the body, the rate is 20–70% for ingested lead; children absorb more than adults.<ref name=health/>

Dermal exposure may be significant for a narrow category of people working with organic lead compounds, but is of little concern for general population. The rate of skin absorption is also low for inorganic lead.<ref name=health/>

According to Agency for Toxic Substance and Disease Registry, a small amount of lead (1%) will store itself in bones and the rest will be excreted through urine and feces within a few weeks of exposure. Children have a harder time excreting lead. Only about 32% of lead will be excreted by a child.<ref>{{Cite web|url=http://www.atsdr.cdc.gov/PHS/PHS.asp?id=92&tid=22|title= Toxic Substances Portal – Lead|publisher=Agency for Toxic Substance and Disease Registry}}</ref>

===Occupational exposure===
Lead is widely used in the production of batteries, metal products (solder and pipes), ammunition and devices to shield X-rays leading to its exposure to the people working in these industries. Use of lead in [[gasoline]], [[paints]] and ceramic products, [[caulking]], and pipe solder has been dramatically reduced in recent years because of health concerns. Ingestion of contaminated food and drinking water is the most common source of lead exposure in humans. Exposure can also occur via inadvertent ingestion of contaminated soil/dust or lead-based paint.<!--A knowledgeable statement concerning the issue of occupational exposure in the manufacture of lead crystal would be appropriate here.-->

===Testing===
Water contamination can be tested with commercially available kits. Analysis of lead in whole blood is the most common and accurate method of assessing lead exposure. Erythrocyte protoporphyrin (EP) tests can also be used to measure lead exposure, but are not as sensitive at low blood lead levels (<0.2&nbsp;mg/L). Lead in blood reflects recent exposure. Bone lead measurements are an indicator of cumulative exposure. While measurements of urinary lead levels and hair have been used to assess lead exposure, they are not reliable.

Pharmaceuticals also require laboratory testing for heavy metals such as lead. The component limit of lead (1.0 μg/g) is a test benchmark for pharmaceuticals, representing the maximum daily intake an individual should have. However, even at this low level, a prolonged intake can be hazardous to human beings.<ref>http://www.caspharma.com/Heavy-Metals-Testing-USP/</ref><ref>http://www.britannica.com/EBchecked/topic/455151/pharmaceutical</ref>

==See also==
*[[Adult Blood Lead Epidemiology and Surveillance]]
*[[Lead-Free Toys Act]]
*[[Medical geology]]
*[[Plumbosolvency]]
*[[Restriction of Hazardous Substances Directive|RoHS directive]]
*[[Banning of leaded petrol]]
{{Subject bar
|portal=Chemistry
|book1=Lead
|book2=Period 6 elements
|book3=Carbon group
|book4=Chemical elements (sorted&nbsp;alphabetically)
|book5=Chemical elements (sorted by number)
|commons=y
|wikt=y
|wikt-search=lead
}}

==References==
{{Reflist|colwidth=35em}}

==Further reading==
* {{ cite journal|last1=Keisch|doi=10.1126/science.155.3767.1238|first1=B.|last2=Feller|first2=R. L.|last3=Levine|first3=A. S.|last4=Edwards|first4=R. R.|title=Dating and Authenticating Works of Art by Measurement of Natural Alpha Emitters|journal=Science|volume=155|issue=3767|pages=1238–1242|year=1967|pmid=17847535|bibcode = 1967Sci...155.1238K }}
*{{ cite journal|doi=10.1126/science.160.3826.413|last=Keisch |first=B|title=Dating Works of Art Through their Natural Radioactivity: Improvements and Applications|journal=Science|volume= 160|issue=3826 |pages=413–415|year=1968|pmid=17740234|bibcode = 1968Sci...160..413K }}
*{{ cite journal| doi=10.1111/j.2151-6952.1968.tb00884.x| last=Keisch|first= B|title=Discriminating Radioactivity Measurements of Lead: New Tool for Authentication|journal=Curator|volume=11|issue=1|pages=41–52|year= 1968}}
*{{ cite book|editor1-first=Jose S.|editor1-last= Casas |editor2-first=Jose |editor2-last=Sordo|url=http://www.google.com/books?id=D9nYWCv_FE4C&printsec=frontcover|title= Lead Chemistry, Analytical Aspects. Environmental Impacts and Health Effects|year= 2006|publisher= Elsevier| isbn= 0-444-52945-4}}

==External links==
*[http://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=96&tid=22 Toxicological Profile for Lead (Update)] Agency for Toxic Substances and Disease Registry (ATSDR). 2007. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.
*[http://www.atsdr.cdc.gov/csem/lead/ ATSDR Case Studies in Environmental Medicine: Lead Toxicity] U.S. [[Department of Health and Human Services]]
*{{dmoz|Science/Chemistry/Elements/Lead/}}
*[http://www.rsc.org/chemistryworld/podcast/element.asp Chemistry in its element podcast] (MP3) from the [[Royal Society of Chemistry]]'s [[Chemistry World]]: [http://www.rsc.org/images/CIIE_lead_48kbps_tcm18-126010.mp3 Lead]
*[http://www.leadfreewheels.org/ Lead-Free Wheels]
*[http://www.epa.gov/waste/hazard/wastemin/nlfwwi.htm National Lead Free Wheel Weight Initiative| Waste Minimization|Wastes|US EPA]

{{Compact periodic table}}
{{Lead compounds}}

[[Category:Chemical elements]]
[[Category:Soil contamination]]
[[Category:Toxicology]]
[[Category:Coolants]]
[[Category:Lead| ]]
[[Category:Poor metals]]
[[Category:Occupational safety and health]]
[[Category:Endocrine disruptors]]
[[Category:Superconductors]]
[[Category:IARC Group 2B carcinogens]]
[[Category:Nuclear reactor coolants]]

{{Link FA|de}}

[[af:Lood]]
[[ang:Lēad]]
[[ar:رصاص]]
[[an:Plomo]]
[[az:Qurğuşun]]
[[bn:সীসা]]
[[zh-min-nan:Iân]]
[[be:Свінец]]
[[bs:Olovo (hemija)]]
[[bg:Олово]]
[[ca:Plom]]
[[cv:Хура тăхлан]]
[[cs:Olovo]]
[[co:Piombu]]
[[cy:Plwm]]
[[da:Bly]]
[[de:Blei]]
[[nv:Dilyį́hí]]
[[et:Plii]]
[[el:Μόλυβδος]]
[[myv:Чопода киве]]
[[es:Plomo]]
[[eo:Plumbo]]
[[eu:Berun]]
[[fa:سرب]]
[[hif:Raanga]]
[[fr:Plomb]]
[[fy:Lead (elemint)]]
[[fur:Plomp]]
[[ga:Luaidhe]]
[[gv:Leoaie]]
[[gl:Chumbo]]
[[hak:Yèn]]
[[xal:Хорлҗн]]
[[ko:납]]
[[hy:Կապար]]
[[hi:सीसा]]
[[hr:Olovo (element)]]
[[io:Plombo]]
[[id:Timbal]]
[[os:Зды]]
[[is:Blý]]
[[it:Piombo]]
[[he:עופרת]]
[[kn:ಸೀಸ]]
[[ka:ტყვია]]
[[kk:Қорғасын]]
[[sw:Risasi (metali)]]
[[kv:Ширысь]]
[[ht:Plon]]
[[ku:Sirb]]
[[mrj:Вӹдвулны]]
[[lbe:ЧӀутӀи]]
[[la:Plumbum]]
[[lv:Svins]]
[[lb:Bläi]]
[[lt:Švinas]]
[[lij:Ciongio]]
[[jbo:cnisa]]
[[hu:Ólom]]
[[mk:Олово]]
[[ml:കറുത്തീയം]]
[[mi:Matā (konganuku)]]
[[mr:शिसे]]
[[ms:Plumbum]]
[[mdf:Киви]]
[[mn:Хар тугалга]]
[[nah:Temētztli]]
[[nl:Lood (element)]]
[[ja:鉛]]
[[no:Bly]]
[[nn:Bly]]
[[oc:Plomb]]
[[pnb:سیسہ]]
[[koi:Ширись]]
[[nds:Blie]]
[[pl:Ołów]]
[[pt:Chumbo]]
[[ro:Plumb]]
[[qu:Titi]]
[[ru:Свинец]]
[[sa:सीसम्]]
[[sco:Leid (element)]]
[[stq:Lood]]
[[sq:Plumbi (element kimik)]]
[[scn:Chiummu]]
[[simple:Lead]]
[[sk:Olovo]]
[[sl:Svinec]]
[[sr:Олово]]
[[sh:Olovo]]
[[fi:Lyijy]]
[[sv:Bly]]
[[tl:Tingga]]
[[ta:ஈயம்]]
[[te:సీసపద్యము]]
[[th:ตะกั่ว]]
[[tg:Сурб]]
[[tr:Kurşun]]
[[uk:Свинець]]
[[ur:سیسہ]]
[[ug:قوغۇشۇن]]
[[vi:Chì]]
[[war:Tinggâ]]
[[wuu:铅]]
[[yi:בליי]]
[[yo:Lead]]
[[zh-yue:鉛]]
[[zh:铅]]

Revision as of 20:12, 5 October 2011

GAY

Retrieved from "https://wiki.riteme.site/w/index.php?title=Lead&oldid=454123727"