lead

• n.

• 鉛

　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　

WordNet

1. tend to or result in; "This remark lead to further arguments among the guests"
2. a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull grey; "the children were playing with lead soldiers" (同)Pb, atomic number 82
3. (sports) the score by which a team or individual is winning
4. the angle between the direction a gun is aimed and the position of a moving target (correcting for the flight time of the missile)
5. thin strip of metal used to separate lines of type in printing (同)leading
6. mixture of graphite with clay in different degrees of hardness; the marking substance in a pencil (同)pencil lead
7. a position of leadership (especially in the phrase `take the lead'
8. an advantage held by a competitor in a race; "he took the lead at the last turn"
9. the playing of a card to start a trick in bridge; "the lead was in the dummy"
10. a news story of major importance (同)lead story
11. the introductory section of a story; "it was an amusing lead-in to a very serious matter" (同)lead-in, lede
12. evidence pointing to a possible solution; "the police are following a promising lead"; "the trail led straight to the perpetrator" (同)track, trail
13. (baseball) the position taken by a base runner preparing to advance to the next base; "he took a long lead off first"
14. travel in front of; go in advance of others; "The procession was headed by John" (同)head
15. take somebody somewhere; "We lead him to our chief"; "can you take me to the main entrance?"; "He conducted us to the palace" (同)take, direct, conduct, guide
16. be ahead of others; be the first; "she topped her class every year" (同)top
17. cause to undertake a certain action; "Her greed led her to forge the checks"
18. bring into a different state; "this may land you in jail" (同)land
19. induce or persuade; "The confession of one of the accused brought the others to admit to the crime as well"
20. take something or somebody with oneself somewhere; "Bring me the box from the other room"; "Take these letters to the boss"; "This brings me to the main point" (同)convey, take
21. go or come after and bring or take back; "Get me those books over there, please"; "Could you bring the wine?"; "The dog fetched the hat" (同)get, convey, fetch
22. cause to happen or to occur as a consequence; "I cannot work a miracle"; "wreak havoc"; "bring comments"; "play a joke"; "The rain brought relief to the drought-stricken area" (同)work, play, wreak, make for
23. attract the attention of; "The noise and the screaming brought the curious"
24. be accompanied by; "Can I bring my cousin to the dinner?"
25. cause to come into a particular state or condition; "Long hard years of on the job training had brought them to their competence"; "bring water to the boiling point"
26. join or connect; "The rooms communicated"
27. transmit thoughts or feelings; "He communicated his anxieties to the psychiatrist" (同)intercommunicate
28. transmit information ; "Please communicate this message to all employees"; "pass along the good news" (同)pass_on, pass, pass along, put across
29. administer Communion; in church
30. be in verbal contact; interchange information or ideas; "He and his sons havent communicated for years"; "Do you communicate well with your advisor?"
31. direct (oneself) somewhere; "Steer clear of him"
32. direct the course; determine the direction of travelling (同)maneuver, manoeuver, manoeuvre, direct, point, head, guide, channelize, channelise
33. cover with graphite
34. a pulley-block used to guide a rope forming part of a ships rigging to avoid chafing
35. going or proceeding or going in advance; showing the way; "we rode in the leading car"; "the leading edge of technology"
36. greatest in importance or degree or significance or achievement; "our greatest statesmen"; "the countrys leading poet"; "a preeminent archeologist" (同)preeminent
37. indicating the most important performer or role; "the leading man"; "prima ballerina"; "prima donna"; "a star figure skater"; "the starring role"; "a stellar role"; "a stellar performance" (同)prima, star, starring, stellar
38. treated or mixed with lead; "leaded gasoline"; "leaded zinc"
39. (of panes of glass) fixed in place by means of thin strips of lead; "leaded windowpanes"
40. having thin strips of lead between the lines of type
41. a unit of length of thread or yarn

PrepTutorEJDIC

1. 《方向を表す副詞[句]を伴って》…‘を'『導く』,案内する / 〈道・灯火などが〉…‘に'道筋を示す;(…へ)…‘を'導く《+『名』+『to』(『into』)+『名』》 / …‘の'先頭になる,1番である / …‘の'『率いる』,指揮する / 〈ある人生・生活〉‘を'経験する,生きる,送る / 『先頭に立つ』,(競技・成績などで)リードスル / 〈人が〉『案内する』,先導する / (…に)〈道などが〉『通じている』《+『to』+『名』》 / (…の)結果となる《+『to』+『名』(do『ing』)》 / 〈U〉《the~》『先頭』,首位 / 〈C〉《a~》相手を引き離した点(時間,距離) / 〈C〉模範,手本(example) / 〈C〉(問題解決の)手がかり,ヒント(clue) / 〈C〉(劇・映画などの)主役,主演俳優 / 〈C〉(新聞報道記事などの本文の前におく要約した)前文,前書き,リード / 先頭の,主要な
2. 〈U〉『鉛』(化学記号はは『pb』) / 〈C〉鉛のおもり,測鉛 / 〈C〉《複数形で》(ガラスをはめる)鉛の枠(わく);《英》(屋根をふくのに用いる)鉛板 / 〈U〉〈C〉黒鉛,鉛筆のしん / 〈U〉《集合的に》(鉛の)弾丸 / …‘に'鉛をかぶせる,鉛を詰める,鉛のおもりを付ける
3. 〈物〉‘を'『持ってくる』 / 〈人が〉(…に)〈人〉‘を'『連れてくる』《+『名』〈人〉+『to』+『名』》 / 〈物事が〉(…に)〈人〉‘を'『来させる』,引き寄せる《+『名』+『to』+『名』》 / 〈物事〉をもたらす,引き起こす / (ある状態・結果・動作などに)…‘を'『する』 / (…に対して)〈訴訟〉を起こす《+『名』+『for』(『against』)+『名』》
4. 〈知識・情報・思想など〉'を'『伝える』,伝達する / 《文》(…に)〈病気・熱・動きなど〉'を'伝染させる《+『名』+『to』+『名』》 / …‘に'聖餐(せいさん)を与える / (…と)『通信する』,連絡する《+『with』+『名』》 / 《文》〈場所・部屋などが〉(…に)通じている,連絡する《+『with』+『名』》
5. 〈船・車・飛行機など〉‘の'『かじをとる』,‘を'操縦する;《しばしば比喩(ひゆ)的に》〈人〉‘を'操る / 〈進路・道〉‘を'操縦して進む / …‘を'導く,‘に'道を教える / 操縦する / 進路をとる / 〈船・車などが〉かじ(ハンドル)がきく / 助言,忠告
6. 去勢された食用の雄ウシ[の子]
7. 開始,第一歩,手始め / 『主導権』 / 独創力,創意工夫;進取の精神 / (一般国民の)発議;発議権の手続き
8. 〈炉の金具など〉‘に'黒鉛を塗る;…'を'黒鉛でみがく
9. 『先導する』,先頭の / 『主要な』,一流の / 指導する / 指導
10. (ガソリンが)四エチル鉛入りの
11. 草原,牧草地(meadow)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/08/31 21:13:16」(JST)

wiki ja

[Wiki ja表示]

Lead
別名	リード
出身地	日本
ジャンル	J-POP
活動期間	2002年 - 現在
レーベル	FLIGHT MASTER（2002年 - 2009年） ポニーキャニオン（2010年 - 現在）
事務所	ライジングプロダクション（RISINGPRODUCTION）
共同作業者	DA PUMP、w-inds.、三浦大知
公式サイト	Lead OFFICIAL SITE
メンバー	谷内伸也 古屋敬多 鍵本輝

Lead（リード）は、日本の男性ダンスボーカルユニットである。所属事務所はライジングプロダクション、レコード会社はポニーキャニオン。

メンバー

• 谷内伸也（たにうち しんや、1987年9月23日 - ）

  大阪府枚方市出身。血液型A型。イメージカラーは緑。

• 古屋敬多（ふるや けいた、1988年6月13日 - ）

  福岡県福岡市出身。血液型A型。イメージカラーは黄。

• 鍵本輝（かぎもと あきら、1988年8月20日 - ）

  奈良県生駒郡斑鳩町出身。血液型O型。イメージカラーは青。

元メンバー

• 中土居宏宜（なかどい ひろき、1985年7月26日 - ）

  大阪府藤井寺市出身。血液型AB型。イメージカラーは赤。2013年3月31日を以て卒業。

略歴

2002年4月からダンススクール「キャレス」大阪校に通っていた中土居宏宜、谷内伸也、鍵本輝が「Rhymix」（リミックス）というユニットを組んで、ストリートライブを行っていた。その後、「flow」（フロウ）と改称し京橋駅付近などで路上パフォーマンスを始め、同年6月に「九州・沖縄 スターライトオーディション2002」で審査員特別賞を受賞した古屋敬多が加わり現在のLeadが結成される。ユニット名の由来は時代を「リード」できる存在になりたい、という意味をこめて自分たちで命名。その後大阪で路上ライブを始め、城天でのライブでは7000人の観客を集めるようになる。
同年夏、先輩であるw-inds.の1st Liveのオープニングアクトを務め全国を廻った。

同年7月31日、シングル「真夏のMagic」でポニーキャニオンのレーベルFLIGHT MASTERよりデビュー。2ndシングル「"Show me the way"」で2002年第44回日本レコード大賞新人賞を受賞。6thシングル「Night Deluxe」で2004年第46回日本レコード大賞金賞を受賞。8thシングル「あたらしい季節へ」で2005年第47回日本レコード大賞金賞を受賞。

リクエスト・ベスト・アルバム『Lead Tracks ～listener's choice～』においてファンを中心に一般からの投票を募り、収録楽曲を決定するといったものを行った。日本のみならず韓国、台湾、香港などでも投票受け付けを行い、リクエスト総数105,571票となった。

2008年7月、鍵本が織田裕二主演のフジテレビ系月9ドラマ「太陽と海の教室」に出演。Leadのメンバーがゴールデン帯枠の連続ドラマにレギュラー出演するのはこれが初めてとなる。2010年1月、谷内がMBS・TBS系ドラマ「新撰組 PEACE MAKER」（土方歳三役）、同年4月、中土居がTBS系ドラマ「タンブリング」に出演。

2008年12月と2009年5月にLeadをメンバー全員でミュージカル「ZIPANGU～遥かなる道～」に、2010年11月と2011年10月には「絆～少年よ、大紙を抱け～」に出演。メンバー個々でも古屋敬多が「新 日ノ丸レストラン」（2011年4月）、「恋する私のベーカリー」（2011年12月）、鍵本輝が「タンブリングVol.2」（2011年5～7月）、「タンブリングVol.3（ケガで降板した木戸邑弥の代役として凱旋公演のみ出演）」（2012年9月）、谷内伸也が「コカンセツ！再演」（2011年9月）などの舞台に出演している。

2013年3月31日、中土居宏宜がLeadを脱退、芸能界から引退した。 2014年2月26日発売の23rdシングルの「サクラ」がオリコンウィークリーチャートで3位を記録した。

2014年9月17日発売の24thシングル「想い出ブレイカー」以降、カップリングにメンバーそれぞれがメインで作詞・作曲した曲が必ず収録されており、作詞、作曲、編曲、セルフ・プロデュースに精力的に取り組んでいる姿勢をうかがわせる。

3人体制で踏み出したLead第2章が始まって以降としては初の、実に約4年ぶりにリリースされた2016年6月8日発売の7thアルバム「THE SHOWCASE」が、2016年6月20日付けのオリコン週間チャートで初登場2位を記録。これにより、1stアルバム「LIFE ON DA BEAT」（2003年4月発売）の初登場5位、そして、19thシングル「Wanna Be With You」（2012年3月発売）の初登場3位を上回る、過去14年で発売してきたシングル・アルバム全作品含めたLead史上最高位の記録が更新された。（※2016年6月14日現在）

作品

シングル

■ … 10位以内　■ … 20位以内　■ … 30位以内

	タイトル	発売日	カップリング曲	最高 順位	登場 回数
2002年
1st	真夏のMagic	7月31日	No doubt 真夏のMagic (MOCH² BRANDNEW CLUB TRACK)	18位	5回
2nd	"Show me the way"	10月17日	Step by Step "Show me the way" (Led on Remix)	7位	6回
2003年
3rd	FLY AWAY	2月5日	SHINING DAY	10位	7回
4th	ファンキーデイズ!	7月30日	ALL MY LIFE ～真夏の海物語～ 真夏のMagic 2003 ～MAGICAL RED HOT SUMMER REMIX～	10位	5回
5th	GET WILD LIFE	12月3日	Field of Soul	9位	7回
2004年
6th	Night Deluxe	6月16日	Here goes!	5位	5回
7th	手のひらを太陽に/Delighted	10月27日	ファンキーデイズ! <Does It Be Funky? Remix>	8位	4回
2005年
8th	あたらしい季節へ	4月13日	Freedom No Rule	6位	4回
9th	ベイビーランニンワイルド	7月6日	Summer Splash	11位	3回
2006年
10th	バージンブルー	3月8日	Cosmic Drive	9位	4回
11th	Summer Madness	6月21日	僕が月に祈る夜 ONE	17位	5回
2007年
12th	Drive Alive	3月14日	GET DIZZY Love & Everything	14位	3回
13th	海	7月18日	空の彼方へ 君は何かが出来る	27位	2回
2008年
14th	STAND UP!	2月6日	Load Sleepin' Flower	20位	4回
15th	Sunnyday	7月30日	Sunnyday (BLUE DRAGON EDIT)	34位	2回
2009年
16th	ギラギラRomantic	8月5日	High テンション DAY Stay with me【AKIRA ver.のみ】 Follow Me【SHINYA ver.のみ】 You're the only one【KEITA ver.のみ】 君 ～さくら～【HIROKI ver.のみ】	12位	4回
2010年
17th	SPEED STAR★	7月28日	Speechless バージンブルー 2010 光【初回限定盤（CD+DVD）のみ】※各種アレンジ違い	11位	3回
2011年
18th	HURRICANE	8月10日	CAN'T STOP アンバランスなKISSをして【初回盤Aのみ】 Sun×You【初回盤Bのみ】 walk【初回盤Cのみ】 What cha gonna? (LIVE MIX)【初回盤Dのみ】 24HRS【通常盤のみ】	8位	3回
2012年
19th	Wanna Be With You	3月14日	COLOR【初回盤4種類共通】 Tick Tock【初回盤Bのみ】 Last Situation【初回盤Cのみ】 Gimme Your Love【初回盤Dのみ】 Hungry Sniper【通常盤のみ】	3位	3回
20th	Still	12月12日	冬色ガール【全種類共通】 ORDINARY【初回盤Bのみ】 anytime【初回盤Cのみ】 Masquerade【初回盤Dのみ】	4位	2回
2013年
21st	Upturn	6月19日	Versus【初回盤A,Bのみ】 Take You Higher【初回盤Cのみ】 Friendship【初回盤Cのみ】 トワイライト【通常盤のみ】	5位	3回
22nd	GREEN DAYS/strings	9月18日	雨のち君【初回盤Aのみ】 Giant Steps【初回盤Bのみ】 アザヤカナセカイ【初回盤Cのみ】 GREEN DAYS (TV drama edit)【通常盤のみ】	4位	4回
2014年
23rd	サクラ	2月26日	With U【全種類共通】 茜色染まるころに【初回盤Aのみ】 Just do it【初回盤Bのみ】 Can't Stop Loving You【初回盤Cのみ】	3位	2回
24th	想い出ブレイカー	9月17日	Summer Love Story【全種類共通】 君と歩く未来【初回盤Aのみ、谷内伸也作詞】 Fairy tale【初回盤Bのみ、鍵本輝作曲】 線香花火【初回盤Cのみ、古屋敬多作詞】	4位	4回
2015年
25th	My One	3月4日	It’s My Style【全種類共通】 Until…【初回盤Aのみ、鍵本輝作曲】 スーパーディスコ【初回盤Bのみ、古屋敬多作詞】 Change myself【初回盤Cのみ、谷内伸也作曲】	6位	3回
26th	約束	11月25日	Always Love【全種類共通】 Wake me up【初回盤Aのみ、鍵本輝作詞作曲】 ムーンライトシャワー【初回盤Bのみ、古屋敬多作詞】 CROSS OVER【初回盤Cのみ、谷内伸也作詞】	5位	2回

アルバム

オリジナルアルバム

枚	発売日	タイトル	最高位	登場回数
1st	2003年4月23日	LIFE ON DA BEAT	5位	6回
2nd	2004年8月25日	BRAИD ИEW ERA	11位	3回
3rd	2005年8月10日	Lead! Heat! Beat!	15位	4回
4th	2006年7月19日	4	18位	2回
5th	2008年3月5日	Feel The Vibes	44位	2回
6th	2012年7月18日	NOW OR NEVER	6位	2回
7th	2016年6月8日	THE SHOWCASE	2位	5回

リクエストベストアルバム

1. Lead Tracks ～listener's choice～（2008年8月6日） 最高順位67位、登場回数1回

参加作品

• buddies（2003年3月19日） 収録曲：「FLY AWAY ～AKIRA'S CONQUISTADOR REMIX～」、「"Show me the way" ～TinyVoice,Production REMIX～」

w-inds.、FLAMEとの合同リミックス・アルバム。

• CHRISTMAS HARMONY ～VISION FACTORY presents～（2007年11月21日） 収録曲：「Ding Dong」、「OkiDoki Christmas」

ヴィジョンファクトリー所属アーティストによる「クリスマス」をテーマに綴られたコンピレーション・アルバム。

• SPRING HARMONY ～VISION FACTORY presents～（2008年2月13日） 収録曲：「Thanks For...」

ヴィジョンファクトリー所属アーティストによる「春」をテーマに綴られたコンピレーション・アルバム。

• FLOWER FESTIVAL ～VISION FACTORY presents～（2008年3月19日） 収録曲：「Dear My Flower」

ヴィジョンファクトリー所属アーティストによる「花」をテーマに綴られたコンピレーション・アルバム。

配信限定

※規格は着うた、着うたフル（その他については楽曲毎に特記）。「24HRS」以降はレコチョク限定配信（☆）、レコチョク先行配信（★）。「24HRS」以降の最高順位はレコチョクチャート。なお、レコチョク限定配信楽曲はCD化に合わせて他の配信サイトでも配信されている。

1. OkiDoki Christmas（2006年12月8日）
2. Ding Dong（2006年12月8日）

   規格：待ちうた（上記2曲）

   上記2曲ともにコンピレーション・アルバム『CHRISTMAS HARMONY ～VISION FACTORY presents～』に収録。

3. Load（2006年12月29日）

   14thシングル「STAND UP!」に収録。

4. 24HRS（2011年3月9日）☆

   規格：待ちうた　最高順位：デイリー3位、週間9位（ともに着うた）

   18thシングル「HURRICANE」（通常盤のみ）に収録。

5. CAN'T STOP（2011年5月11日）☆

   規格：着ムービー、待ちうた　最高順位：週間1位（着ムービー）

   18thシングル「HURRICANE」（全5種類共通）に収録。

6. Wanna Be With You（2011年11月24日）★

   規格：待ちうた　最高順位：デイリー1位、週間8位（ともに着うた）

   シングル・バージョンとして歌詞を一部変更、再録されたものが19thシングルとして発売。

7. Hungry Sniper（2011年12月28日）★

   規格：待ちうた　最高順位；デイリー1位、週間6位（ともに着うた）

   林田健司による書き下ろし。KEITA出演の女性チャンネル♪LaLa TV・LISMOドラマ「恋する私のベーカリー」主題歌。19thシングル「Wanna Be With You」（通常盤のみ）に収録。

未発表曲

全国ツアー、ライブイベントなどで披露されたCD未発売の楽曲。

• 嵐の日々（2004年8月18日）

映画「かまち」VHS版の初回封入特典CD。同映画の挿入歌。

• TRIBAL PARTY

  作詞：Lead / 作曲、編曲：中土居宏宜

• LD style

  作詞：Lead / 作曲：HIROKI, Hayabusa / 編曲：Hayabusa

• I don't give a damn

  作詞：Lead / 作曲、編曲：鍵本輝

Upturn2015～MASTER PLAN～にて披露された。CD化はされていないが同ツアーのDVD、Blu-rayに収録されている。

2016年6月6日0時よりiTunesで、7thアルバム「THE SHOWCASE」の独占先行配信が開始され、アルバム全曲をダウンロードするとボーナストラックとして入手可能となる。

• RIDE ON MUSIC

  作詞、作曲、編曲：Lead

26thシングル「約束」の発売記念イベントで公約として完全セルフプロデュース曲の発表を掲げ、2015年年末に行われた「Lead LIVE SHOUT」にて披露された。

DVD・VHS

※『Lead LIVE TOUR UPTURN 2005』以降はDVDのみの発売。

	発売日	タイトル	規格品番	最高位	備登場回数
1st	2003年9月18日	Lead MOVIES 1	PCVP-53254:VHS PCBP-50910:DVD
2nd	2004年11月17日	Lead 1st live tour ～BRAИD ИEW ERA～	PCVP-53401:VHS PCBP-51334:DVD
3rd	2005年3月16日	Lead MOVIES 2	PCVP-53426:VHS PCBP-51393:DVD
4th	2005年12月7日	Lead LIVE TOUR UPTURN 2005	PCBP-51586	35位	2回
5th	2006年12月6日	LEAD UPTURN 2006 [4]	PCBP-51887	24位	2回
6th	2007年12月12日	Lead Upturn 2007 ～B.W.R～	PCBP-51910	34位	1回
7th	2008年8月6日	Lead MOVIES 3	PCBP-51558	40位	2回
8th	2008年12月3日	Lead Upturn 2008 ～Feel The Vibes～	PCBP-51921	37位	2回
9th	2009年12月9日	Lead Upturn 2009 ～Summer Day & Night Fever～	PCBP-51948	41位	1回
10th	2010年12月8日	Lead Upturn 2010 ～I'll Be Around★～	PCBP-52055	41位	回
11th	2011年2月	Lead drama box ※VISION FACTORY Online Shop限定販売
12th	2011年7月	Short Movie 4 ～Ignition～ ※VISION FACTORY Online Shop限定販売
13th	2011年12月21日	Lead Upturn 2011 ～Sun×You～	PCBP-52085	93位	2回
14th	2012年12月26日	Lead Upturn 2012 ～NOW OR NEVER～	PCBP-52108	38位	1回
15th	2013年12月25日	Lead Upturn 2013 Leap	PCBP-53092	57位	1回
16th	2014年12月24日	Lead Upturn 2014 Attract	PCBP-52310	42位	1回
17th	2015年05月13日	MOVIES 4	PCBP-53125	11位	1回
18th	2015年12月16日	Lead Upturn 2015 MASTER PLAN	PCBP-53134:DVD PCXP-50364:Blu-ray	53位	1回

写真集

• 伝説の序章―Lead写真集（竹書房、2002年10月）
• Lead+FLAME Kyohei "SCHOOL BOYS" in『棒たおし!』（主婦と生活社、2003年3月）
• Lead PERFECT BOOK（主婦と生活社、2003年10月）
• Lead meets JUNON（主婦と生活社、2004年12月17日）
• LEAD TOUR（イーストプレス、2006年10月）
• Leadデビュー10周年アニバーサリーブック「Document」（エムオン・エンタテインメント、2012年7月）　※予約限定販売

ミュージックビデオ

監督	曲名
井上強	「FLY AWAY」「SPEED STAR★」「Show me the way」「手のひらを太陽に」「真夏のMagic」
柿本ケンサク	「STAND UP!」
北平誠治	「My One」「Stand and Fight」「Still」「Wanna Be With You」「サクラ」「想い出ブレイカー」 「約束」「Zoom up」
多田卓也	「Summer Madness」「バージンブルー」「ベイビーランニンワイルド」
土屋隆俊	「Drive Alive」「Sunnyday」「海」
長谷川信	「GET WILD LIFE」「Night Deluxe」「あたらしい季節へ」「ファンキーデイズ!」
Tatsuya Murakami	「Upturn」
モリ○カツ	「ギラギラRomantic」
不明	「GREEN DAYS」

出演

※レギュラー出演のみ。メンバー個人の出演は、それぞれのページ（谷内伸也、古屋敬多、鍵本輝）を参照。

テレビ番組

• 東京MXTV「XEBEC ONLINE」（2003年1月 - 2005年3月30日）
• 台湾TVBS-G「FACTORY GENERATION（F超世代）」（2003年3月13日 - 2005年2月19日）
• テレビ東京「コラボレーションスタジアム」（2003年4月 - 9月）
• テレビ東京「ピカピカプリンス」（2003年10月 - 2004年3月）
• NHK-BS2「大阪発元気ダッシュ!DOYAH」（2003年10月 - 2005年2月）
• 東京MXTV「Lead Generation」（2005年4月 - 2005年9月）
• MUSIC ON! TV「M-ON! Make On The Holiday」Leadレギュラーコーナー「ぶらり～ど」（2006年7月29日 - 2008年2月）
• ディズニー・チャンネル「東京ディズニーリゾート トレジャーハント」（2008年5月 - 2010年7月）

ラジオ番組

• One Step Lead（2002年10月 - 2003年3月、FM AICHI）
• One For The Lead（2003年4月 - 2006年3月、FM NACK5）※「The Nutty Radio Show 鬼玉」内で放送されていた。
• 木曜日の男子会（ - 現在、Fm yokohama 84.7）

映画

• 棒たおし!（2003年）
• かまち（2004年）

舞台

• ミュージカル「ZIPANGU ～遥かなる道～」（2008年12月23日、2008年12月29日）
• ミュージカル「絆 －少年よ、大紙を抱け！－」（2010年11月18日 - 2010年11月23日）
• ミュージカル「絆 2011 －少年よ、大紙を抱け！－」（2011年10月20日 - 2011年10月25日）

脚注

関連項目

• ライジングプロダクション
• DA PUMP
• w-inds.
• 三浦大知

外部リンク

• 公式サイト
• ライジングプロダクション
• Leadcafe（Leadプロデュースのカフェ）
• ポニーキャニオン音楽専用サイトによるページ
• Leadブログ「Leadship～Blog for Leaders by Lead～」
• 鍵本輝オフィシャルブログ「アキラキラッ」（2008年8月8日 - 2011年9月20日、更新終了）
• Lead_tv (@Lead_tv) - Twitter
• Lead公式YouTubeチャンネル

wiki en

[Wiki en表示]

This article is about the metal. For other uses, see Lead (disambiguation).

Lead,  ₈₂Pb

General properties
Name, symbol	lead, Pb
Pronunciation	/ˈlɛd/ LED
Appearance	metallic gray
Lead in the periodic table
Sn ↑ Pb ↓ Fl thallium ← lead → bismuth
Atomic number (Z)	82
Group, block	group 14 (carbon group), p-block
Period	period 6
Element category	post-transition metal
Standard atomic weight (±) (Ar)	207.2(1)
Electron configuration	[Xe] 4f14 5d10 6s2 6p2
per shell	2, 8, 18, 32, 18, 4
Physical properties
Phase	solid
Melting point	600.61 K ​(327.46 °C, ​621.43 °F)
Boiling point	2022 K ​(1749 °C, ​3180 °F)
Density near r.t.	11.34 g/cm3
when liquid, at m.p.	10.66 g/cm3
Heat of fusion	4.77 kJ/mol
Heat of vaporization	179.5 kJ/mol
Molar heat capacity	26.650 J/(mol·K)
vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 978 1088 1229 1412 1660 2027
Atomic properties
Oxidation states	4, 3, 2, 1, −1, −2, −4 ​(an amphoteric oxide)
Electronegativity	Pauling scale: 1.87
Ionization energies	1st: 715.6 kJ/mol 2nd: 1450.5 kJ/mol 3rd: 3081.5 kJ/mol
Atomic radius	empirical: 175 pm
Covalent radius	146±5 pm
Van der Waals radius	202 pm
Miscellanea
Crystal structure	​face-centered cubic (fcc)
Speed of sound thin rod	1190 m/s (at r.t.) (annealed)
Thermal expansion	28.9 µm/(m·K) (at 25 °C)
Thermal conductivity	35.3 W/(m·K)
Electrical resistivity	208 nΩ·m (at 20 °C)
Magnetic ordering	diamagnetic
Young's modulus	16 GPa
Shear modulus	5.6 GPa
Bulk modulus	46 GPa
Poisson ratio	0.44
Mohs hardness	1.5
Brinell hardness	38–50 MPa
CAS Number	7439-92-1
History
Discovery	Middle Easterns (7000 BCE)
Most stable isotopes of lead
iso NA half-life DM DE (MeV) DP 202Pb syn 53000 y ε 0.0497 202Tl 204Pb 1.4% >1.4×1020 y (α) 1.972 200Hg 205Pb trace 1.53×107 y ε 0.051 205Tl 206Pb 24.1% – (α) 1.1366 202Hg 207Pb 22.1% – (α) 0.3915 203Hg 208Pb 52.4% >2×1019 y (α) 0.5188 204Hg 210Pb trace 22.3 y β− 0.064 210Bi
Decay modes in parentheses are predicted, but have not yet been observed

Lead (/lɛd/) is a chemical element in the carbon group with symbol Pb (from Latin: plumbum) and atomic number 82. It is a soft, malleable and heavy post-transition metal. Freshly cut, solid lead has a bluish-white color that soon tarnishes to a dull grayish color when exposed to air; the liquid metal has shiny chrome-silver luster. Lead has the highest atomic number of any non-radioactive element (two radioactive elements, namely technetium and promethium, are lighter), although the next higher element, bismuth, has one isotope with a half-life that is long enough (over one billion times the estimated age of the universe) to be considered stable. Lead's four stable isotopes each have 82 protons, a magic number in the nuclear shell model of atomic nuclei. The isotope lead-208 also has 126 neutrons, another magic number, and is hence double magic, a property that grants it enhanced stability: lead-208 is the heaviest known stable nuclide.

Lead is used in building construction, lead-acid batteries, bullets and shot, weights, as part of solders, pewters, fusible alloys, and as a radiation shield.

If ingested or inhaled, lead and its compounds are poisonous to animals and humans. Lead is a neurotoxin that accumulates both in soft tissues and the bones, damaging the nervous system and causing brain disorders. Excessive lead also causes blood disorders in mammals. Lead poisoning has been documented since ancient Rome, ancient Greece, and ancient China.

Etymology

The modern English word "lead" is of Germanic origin; it comes from the Middle English leed and Old English lēad (with the macron above the "e" signifying that the vowel sound of that letter is long). The Old English word is derived from the Proto-Germanic *lauda- ("lead"); this word is not known in itself, but rather reconstructed, which is marked by an asterisk. According to the linguistical hypothesis, this word bore descendants in most Germanic languages (with a major exception being German) of exactly the same meaning.

The origin of the Proto-Germanic *lauda is not agreed on in the linguistical community. One hypothesis suggests it is derived from Proto-Indo-European *lAudh-("lead"; capitalization of the vowel is equivalent to the macron). Another hypothesis suggests it is borrowed Proto-Celtic *ɸloud-io- ("lead"), which is related to the Latin plumbum, which gave the element its chemical symbol Pb. The origin of *ɸloud-io- presumably pre-dates the Proto-Indo-European language; while it is yet unknown, it is suggested it is also the origin of Proto-Germanic *bliwa- (which also means "lead"), from which stemmed the German Blei ("lead").

The name of the chemical element is not related to the verb of that same spelling, the latter derived from (eventually) Proto-Germanic *laidijan- ("to lead").

Physical characteristics

Atomic configuration

A lead atom has 82 electrons, arranged in an electronic configuration of [Xe]4f¹⁴5d¹⁰6s²6p². The first and second ionization energies—energies required to remove an electron from a neutral atom and an electron from a resulting singly charged ion—of lead combined are close to those of tin, its upper group 14 neighbor; this proximity is caused by the 4f shell—no f shell is present in the atoms of the previous group 14 elements—and the thereby following lanthanide contraction. However, the first four ionization energies of lead combined exceed those of tin, opposite to what the periodic trends would predict. For that reason, unlike tin, lead is reluctant to form the +4 oxidation state in inorganic compounds (see below). Such unusual behavior is rationalized by relativistic effects, which are increasingly stronger closer to the bottom of the periodic table; one of such effects is the spin–orbit interaction, particularly the inert pair effect, which stabilizes the 6s orbital. Furthermore, with increasing atomic radii down the group, the energy that would be released by the formation of two additional bonds is no longer enough to compensate the higher amount of energy required to ionise the 6s electrons.

All previous elements in group 14 have a stable or metastable allotropes in which it crystallizes in the diamond cubic structure, involving covalent bonds. In this structure, each atom is tetrahedrally coordinated, indicating that all four bonds are equivalent, obtaining the lowest possible energy. To explain this, in spite of the fact that two of the electrons are in s-orbitals and the other two in higher-energy p-orbitals, orbital hybridization is invoked, in which one of the electrons is "promoted" from an s-orbital to a p-orbital, and then all form four intermediate hybrid orbitals in a process called sp³ hybridization. The inert pair effect affects the crystal structure of lead, because the promotion of an s-electron becomes inefficient energetically and is larger than the amount of energy that would be released from the additional bonds formed. As such, only the p-electrons can be involved in bonding; hence, lead undergoes metallic bonding, in which only the p-electrons are delocalised and shared between the Pb²⁺ ions, resulting in a face-centered cubic structure like those of the similarly-sized divalent alkaline earth metals calcium and strontium.

Bulk properties

A sample of lead freshly solidified from a molten state

Lead is a bright silvery metal with a very slight shade of blue in a dry atmosphere. It tarnishes on contact with air, forming a complex mixture of compounds whose color and composition depend on conditions, sometimes with significant amounts of carbonates and hydroxycarbonates; a common reaction chain is the initial formation of the oxide by corrosion by oxygen followed by reactions of the resulting oxide with carbon dioxide to yield lead carbonate. Lead's characteristic properties include high density, softness, ductility, malleability, poor electrical conductivity compared to other metals, high resistance to corrosion, and ability to react with organic chemicals.

Lead has only one common allotrope, which is face-centered cubic, with the length of an edge of a unit cell being 349 pm. Unlike the other elements in its group, it does not have a diamond cubic allotrope. This, along with a high atomic weight, greatly adds to the great density of lead; its value—11.34 g·cm⁻³—in accordance with the periodic trends, is higher than those of germanium and tin—5.23 and 7.29 g·cm⁻³. Moreover, it exceeds those of many other common metals: iron (7.87 g·cm⁻³), copper (8.93 g·cm⁻³), zinc (7.14 g·cm⁻³), and so on. This property is one of the best-known characteristics of lead: for example, consider the idiom go down like a lead balloon. However, some rarer metals are far denser than lead: tungsten, gold (both 19.3 g·cm⁻³), with the densest metal known—osmium—having a density of 22.59 g·cm⁻³, about twice that of lead.

At 327.5 °C (621.5 °F), lead melts; the melting point exceeds that of tin (232 °C, 449.5 °F), but is significantly below that of germanium (938 °C, 1721 °F). The boiling point of lead is 1749 °C (3180 °F), below those of both tin (2602 °C, 4716 °F) and germanium (2833 °C, 5131 °F).

Isotopes

Main article: Isotopes of lead

Lead has four observationally stable isotopes, lead-204, lead-206, lead-207, and lead-208. The relative multitude of its stable isotopes relies on the fact that lead's atomic number of 82 is even. With its high atomic number, lead is the second-heaviest element that occurs naturally in the form of isotopes that could be treated as stable for any practical applications: bismuth has a higher atomic number of 83, but its only primordial isotope was found in 2003 to be actually very slightly radioactive. The four stable isotopes of lead could theoretically undergo alpha decay to isotopes of mercury with release of energy as well, but this has not been observed for any of them: accordingly, their predicted half-lives are extremely long, ranging up to over 10¹⁰⁰ years. As such, lead is often quoted as the heaviest stable element.

Three of these isotopes also found in three of the four major decay chains: lead-206, lead-207, and lead-208 are the final decay products of uranium-238, uranium-235, and thorium-232, respectively; the decay chains are called the uranium series, actinium series, and thorium series, respectively. Since the amounts of them in nature depend also on the presence of other elements, the isotopic composition of natural lead varies between samples: in particular, the relative amount of lead-206 may vary between 20.84% and 27.78%, and the relative amount of lead-208 may vary between 52.4% in normal samples to 90% in thorium ores. (For this reason, the atomic weight of lead is given with such imprecision, to only one decimal place.) As time passes, relative amounts of lead-206 and lead-207 to that of lead-204 increase, since the former two are supplemented by radioactive decay of heavier elements and the latter is not; this allows for lead–lead dating. Analogously, as uranium decays (eventually) into lead, their relative amounts change; this allows for uranium–lead dating.

Apart from the stable isotopes, which make up almost all of lead that exists naturally, there are trace quantities of a few radioactive isotopes. One of them is lead-210; although it has a half-life of 22.3 years, a period too short to allow any primordial lead-210 to still exist, some small non-primordial quantities of it occur in nature, because lead-210 is found in the uranium series: thus, even though it constantly decays away, its amount is also constantly regenerated by decay of its parent, polonium-214, which, while also constantly decaying, is also supplied by decay of its parent, and so on, all the way up to original uranium-238, which has been present for billions of years on Earth. Lead-210 is particularly well known for helping to identify ages of samples containing it, which is performed by measuring lead-210 to lead-206 ratios (both isotopes are present in a single decay chain). Lead-214 is also present in the decay chain of natural uranium-238, lead-212 is present in that of natural thorium-232, and lead-211 is present in that of natural uranium-235; therefore, traces of all three of these isotopes exist naturally as well. Lastly, very minute traces of lead-209 are also present from the cluster decay of radium-223, one of the daughter products of natural uranium-235. Hence, natural lead consists of not only the four stable isotopes, but also minute traces of another five short-lived radioisotopes.

In total, thirty-eight isotopes of lead have been synthesized, those with mass numbers of 178–215. Lead-205 is the most stable radioisotope of lead, with a half-life of around 1.5×10⁷ years. The second-most stable radioisotope is the synthetic lead-202, which has a half-life of about 53000 years, longer than any of the natural trace radioisotopes. Additionally, 47 nuclear isomers (long-lived excited nuclear states), corresponding to 24 lead isotopes, have been characterized. The longest-lived isomer is lead-204m2 (half-life of about 1.1 hours).

Chemical characteristics

See also: Compounds of lead

Lead shows two main oxidation states: +2 and +4. While the latter is common for the group 14, stability of the former is increasing down the group: it is virtually non-existent for carbon and silicon, extremely minor for germanium, important (but not prevailing) for tin, and is the more important for lead: even the strongest oxidizing agents among the elements, oxygen and fluorine, oxidize lead to only lead(II) initially. This is caused by the relativistic effects, more specifically, the inert pair effect, which manifests itself when a great difference in electronegativity between lead and the anions (oxide, halides, nitrides) is present, as this results in positive charge on lead and then leads to a stronger contraction of the 6s orbital than the 6p orbital, making the 6s orbital rather inert in ionic compounds. However, this is not applicable to compounds in which lead forms covalent bonds to elements of similar electronegativity such as carbon in organolead compounds, where the sp³ hybridization in compounds is still the energetically preferred one; as such, lead, similarly to carbon, is dominantly tetravalent in organolead compounds. The spin–orbit interaction not only stabilizes the 6s electron levels, but also two of the six 6p levels; and lead has just two 6p electrons. This effect takes part in making lead slightly less reactive chemically.

The figures for electrode potential show that lead is only slightly easier to oxidize than hydrogen. Lead thus can dissolve in acids, but this is often impossible due to specific problems (such as the formation of insoluble salts). Electronegativity, although often thought to be constant for each element, is a variable property; lead shows a high electronegativity difference between values for lead(II) and lead(IV)—1.87 and 2.33, accordingly. This marks the reversal of the trend of stability of the +4 oxidation state in group 14 down the group from increasing to decreasing; tin, for comparison, has electronegativities of 1.80 and 1.96 in the +2 and +4 oxidation states respectively.

Reactivity

Powdered lead burns with a bluish-white flame. As with many metals, finely divided powdered lead exhibits pyrophoricity. Bulk lead released to the air forms a protective layer of insoluble lead oxide, which covers the metal from undergoing further reactions. Other insoluble compounds, such as sulfate or chloride, may form the protective layer if lead is exposed to a different chemical environment.

Fluorine reacts with lead at room temperature, forming lead(II) fluoride. The reaction with chlorine is similar, although it requires heating: the chloride layer diminishes the reactivity of the elements. Molten lead reacts with all the chalcogens.

Presence of carbonates or sulfates results in the formation of insoluble lead salts, which protect the metal from corrosion. So does carbon dioxide, as the insoluble lead carbonate is formed; however, an excess of the gas leads to the formation of the soluble bicarbonate, which makes the use of lead pipes dangerous. Water in the presence of oxygen attacks lead to start an accelerating reaction. Lead also dissolves in quite concentrated alkalis (≥10%) because of the amphoteric character and solubility of plumbites.

The metal is normally not attacked by sulfuric acid; however, concentrated acid does dissolve lead thanks to complexation. Lead does react with hydrochloric acid, albeit slowly, and nitric acid, quite actively, to form nitrogen oxides and lead(II) nitrate. Organic acids, such as acetic acid, also dissolves lead, but this reaction requires oxygen as well.

Inorganic compounds

Lead(II)

Most inorganic compounds that lead forms are lead(II) compounds. This includes binary compounds; lead forms such compounds with many nonmetals, but not with all of them, as for example there is no known lead carbide.

Even though most lead(II) compounds are ionic, they are not as ionic as those of many other metals. In particular, many lead(II) compounds are water-insoluble. In solution, lead(II) ions are colorless, but under specific conditions, lead is capable of changing its color. Unlike tin(II) ions, these do not react as reducing agents in solution. Lead(II) ions partially hydrolyze in aqueous solution to form Pb(OH)⁺ and finally Pb₄(OH)₄ (in which hydroxyls act as bridging ligands).

Lead monoxide exists in two allotropes, red α-PbO and yellow β-PbO, the latter being stable only from around 488 °C. It is the most commonly applicable compound of lead. However, its hydroxide counterpart, lead(II) hydroxide, is not capable of existence outside solutions; in solution, it is known to form anions, plumbites. Lead commonly reacts with the heavier chalcogens. Lead sulfide can only be dissolved in strong acids. It is a semiconductor, a photoconductor, and an extremely sensitive infrared radiation detector. A mixture of the monoxide and the monosulfide when heated forms the metal. The other two chalcogenides are photoconducting as well.

Lead dihalides are known and well-characterized; this refers to not only the binary halides (even including the diastatide), but also mixed ones, such as PbFCl, etc. The difluoride is the first ionically conducting compound to have been discovered. The other dihalides decompose on exposure to ultraviolet or visible light, especially notably for the diiodide. There are anion counterparts for the heavier three dihalides, such as PbCl4−
6. Many pseudohalides are also known.

Lead(IV)

Few lead(IV) compounds are known. Inorganic lead(IV) compounds are typically strong oxidants or exist only in highly acidic solutions. Lead(II) oxide gives a mixed oxide on further oxidation, Pb
3O
4. It is described as lead(II,IV) oxide, or structurally 2PbO•PbO
2, and is the best-known mixed valence lead compound. Lead dioxide is a strong oxidizing agent, capable of oxidizing hydrochloric acid. Like lead monoxide, lead dioxide is capable of forming anions, plumbates. Lead tetrafluoride, a yellow crystalline powder, is stable, but less stable than the difluoride. Lead tetrachloride decomposes at room temperature, lead tetrabromide is less stable still and the existence of lead tetraiodide is questionable. Lead disulfide, like the monosulfide, is a semiconductor. Lead(IV) selenide is also known.

Other oxidation states

A few compounds exist in oxidation states other than +2 and +4, but they do not have a great impact on lead chemistry from either theoretical or industrial perspective. Lead(III) may be obtained under specific conditions as an intermediate between lead(II) and lead(IV), in larger organolead complexes rather than by itself. This oxidation state is not specifically stable, as the lead(III) ion (as well as, consequently, larger complexes containing it) is a radical; the same applies for lead(I), which can also be found in such species. Negative oxidation states can occur as Zintl phases, as either free lead anions, for example, in Ba
2Pb, with lead formally being lead(−IV), or in oxygen-sensitive cluster ions, for example, in a trigonal bipyramidal Pb5−
2 ion, where two lead atoms are lead(−I) and three are lead(0): this illustrates lead's proclivity towards catenation, an ability shared with tin. In such anions, each atom is at a polyhedral vertex and contributes two electrons to each covalent bond along an edge from their sp³ hybrid orbitals, the other two being an external lone pair. The shapes of such anions may be determined by Wade's rules.

Organolead

Main article: Organolead compound

Lead can form long singly- or multiply-bonded chains (catenas) and so shares some covalent chemistry with its lighter homolog carbon. This tendency is much lower for lead because the Pb–Pb bond energy (98 kJ/mol) is much lower than for the C–C bond (356 kJ/mol). Lead atoms can build metal–metal bonds of order up to three. Lead also forms covalent bonds with carbon to produce organolead compounds similar to but generally less stable than typical organic compounds, because the Pb–C bond is rather weak.

The simplest lead analog of an organic compound is plumbane, the lead analog of methane. It is unstable against heat, decaying in heated tubes, and thermodynamically; in general, little is known about chemistry of plumbane, as it is so unstable. A lead analog of the next alkane, ethane, is not known. Two simple plumbane derivatives, tetramethyllead and tetraethyllead, are the best-known organolead compounds. These compounds are relatively unstable against heating—tetraethyllead starts to decompose at only 100 °C (210 °F)—as well as sunlight or ultraviolet light. General oxidizing nature of organolead compounds find its use in chemistry: tetraethyllead is produced in larger quantities than any other organometallic compound; lead tetraacetate is an important laboratory reagent for oxidation in organic chemistry. Other organolead compounds, including homologs of the said compounds, are still less chemically stable.

Lead readily forms an equimolar alloy with sodium metal that reacts with alkyl halides to form organometallic compounds of lead such as tetraethyllead. Plumbane may be obtained in a reaction between metallic lead and atomic (not molecular) hydrogen. Atoms of chlorine or bromine displace alkyls in tetramethyllead and tetraethyllead; hydrogen chloride, a by-product of the previous reaction, further reacts with the halogenated molecules to complete mineralization—a chemical reaction or a series of reactions transforming an organic compound into an inorganic one—of the original compounds, yielding lead dichloride.

Origin and occurrence

In space

Chart representing the final part of the s-process from mercury to polonium. Red horizontal lines with a circle in their right ends represent neutron captures; right-upward blue arrows represent beta decays; left-downward green arrows represent alpha decays; right-downward cyan arrows represent electron captures.

Primordial lead—the isotopes lead-204, lead-206, lead-207, and lead-208—was created by the s-process and the r-process. The letter "s" stands for "slow" or "slow neutron capture", and the letter "r" stands for "rapid neutron capture": in the s-process another capture takes a long time, centuries or millennia, while the r-process takes only tens of seconds to result in a heavy nuclide of lead's mass. In the s-process, a nucleus in a star captures another slow neutron, and if the resulting nucleus is unstable, it typically undergoes a beta decay to become an element of the next atomic number. Lead-204 is created from short-lived thallium-204; on capturing another neutron, it becomes lead-205, which, while unstable, is stable enough to generally last longer than a capture takes (its half-life is around 15 million years). Further captures result in lead-206, lead-207, and lead-208. On capturing another neutron, lead-208 becomes lead-209, which quickly decays into bismuth-209, which on capturing another neutron becomes bismuth-210, which either undergoes an alpha decay to result in thallium-206, which would beta decay into lead-206, or a beta decay to yield polonium-210, which would inevitably alpha decay into lead-206 as well, and the cycle ends at lead-206, lead-207, lead-208, and bismuth-209. As a result, relative abundances of the three have stable lead isotopes are multiplied by a "cycling factor", which depends on the conditions of the process. Furthermore, lead-208 and bismuth-209 have a very low cross section towards neutron capture because of their closed neutron shell at neutron number 126. Lead and bismuth are thus very common in stars, in which nucleosynthesis mostly happens through the s-process.

Apart from the s-process, the latter three isotopes have been synthesized as a result of the r-process (lead-204 is not produced in this manner because its isobar mercury-204 is stable, and it is not formed as a decay product of r-process products). The r-process happens in mediums of great electron density. In such conditions, beta decay is blocked, because the high electron density fills all available free electron states up to a Fermi energy which is greater than the energy of nuclear beta decay. But nuclear capture of those free neutrons can still occur, and it causes neutron enrichment of matter. This results an extremely high density of free neutrons which cannot decay, and, correspondingly, a large neutron flux and high temperatures, which is the reason why neutron capture occurs much faster than beta decay. However, the r-process does not directly form as much lead as the s-process, because neutron-rich nuclei with mass numbers 206–208 that would decay to lead are not magic, unlike those that reach the closed neutron shell at neutron number 126 and decay to the platinum group metals around mass number 194. This effect is nevertheless masked, because these lead isotopes are also located at the end of three major decay chains (see above), they are created by the decay of the heavier elements, which are also created by the r-process. Nuclides with mass numbers between 210 and 231 inclusive, as well as 233 and 234 (polonium through actinium, as well as protactinium), quickly undergo alpha and beta decay to stable lead and bismuth isotopes. However, nuclides with mass numbers 232 as well as 235 and above soon decay to the extremely long-lived isotopes of thorium and uranium, which decay very slowly to lead. Hence, the amount of lead in the universe is still slowly increasing.

Solar System abundances

Atomic number	Element	Relative amount
42	Molybdenum	1.0
46	Palladium	0.3
50	Tin	0.9
52	Tellurium	1.6
56	Barium	1.2
80	Mercury	0.1
82	Lead	1
92	Uranium	0.0052

The isotopes at the end of the chains make up around 98.02% lead in the universe, with non-radiogenic lead-204 making up slightly less than two percent. Lead is not an abundant element in general—its per-particle abundance in the Universe is 0.06 ppb—still, it is an order of magnitude more abundant than mercury, and further exceeds those of most other elements of similar atomic numbers. After element 40 (zirconium), no element is at least twofold as abundant as lead, and there is no element as abundant as lead starting after element 56 (barium). Lead is three times as abundant as platinum, ten times as mercury, and twenty times as gold. Per mass, lead's abundance is 10 ppb—the difference between the per-mass and per-particle abundances is justified by mass difference between lead isotopes and the most common elements: the most common nuclide in the Universe, hydrogen-1, has a mass of approximately one atomic mass unit, while those of lead isotopes have masses of over 200 atomic mass units.

On Earth

Lead is a quite common element in the Earth's crust for its high atomic number.

Since lead commonly reacts with sulfur (see above), it is classified as a chalcophile using the Goldschmidt classification. Lead is likely to form minerals that do not sink into the core but that stay above on Earth in its crust, even though without sinking deep into it. Lead's abundance in the Earth's crust is 16 ppm. This results in a great availability of lead minerals and easy extraction of the metal; for this reason, the mineral form of its sulfide, galena, has been known for millennia, as was the metal itself (see below). Lead's pronounced chalcophilic character is close to those of zinc and copper; as such, it is usually found in ore and extracted together with these metals. Metallic lead does occur in nature, but it is rare. As a result of lead's chemistry, it occurs in primary minerals exclusively as lead(II), unlike tin, which always occurs as tin(IV). Lead deposits can be hydrothermal vein, impregnation, and replacement deposits; volcanogenic sedimentary deposits; and hydrothermal or marine sedimentary deposits. World resources of lead exceed 2 billion tons. Massive resources are located in Australia, China, Ireland, Mexico, Peru, Portugal, Russia, and the United States. World reserves—resources ready to be mined for which that would be economically feasible—totaled 89 million tons in 2015, of which Australia had 35 million, China had 15.8 million, and Russia had 9.2 million.

The main lead mineral is galena (PbS). Galena is mostly found with other minerals, mostly zinc ores. Most other lead minerals are normally related to galena in some way; for example, boulangerite, Pb
5Sb
4S
11, is a mixed sulfide derived from galena; anglesite, PbSO
4, is a product of galena oxidation; cerussite or white lead ore, PbCO
3, is a decomposition product of galena. Zinc, copper, arsenic, tin, anitmony, silver, gold, and bismuth are common impurities in lead minerals. Typical background concentrations of lead do not exceed 0.1 μg/m³ in the atmosphere; 100 mg/kg in soil; 5 μg/L in freshwater and seawater.

History

World lead production peaking in the Roman period and the rising Industrial Revolution

(present on the picture = 1980)

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 easily smeltable. Metallic lead beads dating back to 7000–6500 BCE, if not before that, have been found in Asia Minor; this indicates lead was the first metal ever to be smelted. Since then, the metal has been used by many ancient peoples. A major reason for the spread of lead production was its association with silver, which may be obtained by burning galena, a widespread lead mineral. The Ancient Egyptians are thought to have used lead for sinkers in fishing nets, in glazes, glasses and enamels, and for ornaments; they also were the first to use lead for cosmetics, a use that would continue through millennia to Ancient Greece and far beyond. Various civilizations of the Fertile Crescent used lead as a writing material, as currency, and for construction. The Ancient Chinese used lead as a stimulant in the royal court, a currency, and a contraceptive; lead also had a few uses, such as making amulets, for the Indus Valley civilization and the Mesoamericans. Peoples of eastern and southern Africa are known to exercise wire drawing.

Lead Roman pipes inscribed IMP.VESP.VIIII.T.IMP.VII.COS.CN.­IULIO.AGRICOLA.LEG.AUG.PR.PR.

Lead mines were worked in 2000 BCE in the Iberian peninsula by the Phoenicians; and also in Athens, Carthage, and Sicily. Lead was mined in Ancient China before 1000 BCE. With the development of mining and its territorial expansion in Europe and across the Mediterranean, Rome became the greatest producer of lead during the classical era, with an estimated annual output equaling 80,000 tonnes. The Romans obtained lead mostly as a by-product of extensive silver smelting. Lead mining occurred in Central Europe, Britain, the Balkans, Greece, Anatolia, and Hispania, which alone accounted for 40% of world production. Lead was used for making water pipes in the Roman empire and consequently the Latin word for the metal, plumbum, was the origin of the English word "plumbing" and its derivatives—even though some Romans, such as Vitruvius, were able to recognize its danger for health. Nevertheless, a number of researchers suggest lead poisoning was one of the reasons behind the fall of Rome. Lead poisoning—a condition in which one becomes dark and cynical—was called "saturnine", after the ghoulish god of Saturn; the metal was also considered the father of all metals. It was easily available in the Roman society, and as such, its social status was low.

During the ancient and classical eras, (and even far beyond them, until the 17th century), tin was often not distinguished from lead or seen as a different kind of the metal that lead is: Romans called lead plumbum nigrum (literally, "black lead"), while tin was called plumbum candidum (literally, "bright lead"). Their association through history can also be seen in other languages: the word olovo in Czech translates to "lead", but in Russian the cognate олово (olovo) means "tin". In addition to that, lead also bore a close relation to antimony: Both elements commonly occur as sulfides (galena and stibnite), often together. Pliny declared stibnite would give lead on heating, whereas the mineral on heating actually produces antimony. The originally South Asian surma—"galena" in English—spread across Asia with that meaning, and also gave its name to antimony in a number of Central Asian languages, as well as Russian.

Papal bull of 1637 with a lead stamp

Lead plumbing in Western Europe may have been continued beyond the fall of the Western Roman Empire into the medieval era, but lead mining in Europe in general fell into decline, and the largest lead production was conducted in South and East Asia, where lead output underwent a strong growth. In European alchemy, lead continued its status of the oldest metal and its association with Saturn—this time, the planet named after the Roman god rather than the god himself. Alchemists accordingly used Saturn's symbol (the scythe, ♄) to refer to lead. During the period, lead has become increasingly more used as for wine adulteration. This practice was declared forbidden in 1498 by a papal bull, but it continued long past the date, being a reason of various mass poisonings up to late 18th century. In the wake of the Renaissance, the printing press was invented, and lead served as a key material for its parts, starting with the Johannes Gutenberg's press; however, lead dust also was commonly inhaled by operators, causing lead poisoning. Additionally, firearms were invented approximately at the same time, and lead, despite its expense over iron, became a chief material for making bullets, because it made less damage to iron gun barrels, had a higher density (which allowed better retaining velocity and energy), and its lower melting point made production much easier: bullets could be made on wooden fire. Lead was extensively used in cosmetics at the time in Western Europe by the aristocracy, as whitened faces were seen as a sign of modesty. The practice eventually expanded to white wigs and eyeliners, and it only faded out with the French Revolution in the late 18th century; one effect of such prolonged contacts with lead was teeth rotting and teeth replacements often were also made of lead (which temporarily gave sweet breath), inducing further damage to the organism. (A similar fashion appeared in Japan in the 18th century with the emergence of the geishas, with the practice continuing long into the 20th century and the white face becoming a "symbol of a Japanese woman"; lead was commonly used as a face whitener.)

In the New World, lead was first produced soon after the European settlers had arrived; the earliest recorded lead production dates to 1621, in the Colony of Virginia that had been founded fourteen years earlier. In Australia, mining was introduced by the colonists as well, and they opened the first mine on the continent—a lead mine—in 1841. However, centuries before the Europeans were able to start the colonization of Africa in the late 19th century, lead mining was known in the Benue Trough and the lower Congo basin, where lead was used for trade with the Europeans and as a currency.

Lead mining in the upper Mississippi River region in the United States in 1865

In the second half of the 18th century, Britain and later continental Europe and then the United States entered the Industrial Revolution. During the period, lead mining proved important; the Industrial Revolution was the first time to have greater lead production rates than those of Rome. Britain was the leading producer during the period, losing the status of the greatest producer by the mid-19th century with depletion of its mines and development of lead mining in Germany, Spain, and the United States. The United States took the lead by 1900; other non-European nations—in particular, Canada, Mexico, and Australia—started their massive lead production, and by 1900, Europe's output of lead fell below that elsewhere. A great share of demand of lead came from plumbing and painting—lead paints had been invented and regularly used; with invention of gasoline in late 19th century, lead was extensively used as an additive. At this time, more people—the working class—contacted the metal, and this led to the increase of the numbers of those poisoned by lead. This also led to research of effects of lead intake: lead was proven to be more dangerous in its fume form than as a solid metal; lead poisoning and gout were linked (Alfred Baring Garrod noted a third of his gout patients was plumbers and painters); effects of chronic ingestion of lead, including mental disorders, were all studied in the 19th century. The first political acts to decrease the degree of lead poisoning in factories followed in the 1870s and 1880s in the United Kingdom.

Promotional poster for Dutch Boy lead paint, United States, 1912

Further evidence of the threat lead posed to human organisms were revealed in the late 19th and early 20th centuries—mechanisms of the harm were better realized, and lead blindness was documented—and countries in Europe and the United States started efforts to reduce the amount of lead a regular person contacts with. The last major innovation to impose contact with lead on humans was adding tetraethyllead to gasoline, invented in the United States in 1921; it was phased out in the U.S. and the European Union by 2000. Most European countries banned usage of lead paint for interiors by 1930. The result of many regulations and bans put on lead products was significant: in the last quarter of the 20th century, percentage of people with excessive lead blood levels dropped from over three quarters of the population to slightly over two percent in the U.S. By the end of the 20th century, the main good made of lead was the lead–acid battery, which possesses no direct threat to humans. That allowed for a consistent lead production in the industrialized countries. From 1960 to 1990, lead output in the Western Bloc grew by 31%. The share of the world's lead production of the Eastern Bloc increased from 10% and 30% from 1950 to 1990, with the Soviet Union being world's largest producer during the mid- and late 1970s and the 1980s, and China started a massive lead production in the late 20th century. Unlike the European communist countries, China was largely unindustrialized by mid-20th century; in 2004, China surpassed Australia as the largest producer of lead. However, in part similarly to the European industrialization, lead does have a negative effect on the global health in the country.

Production

Historical evolution of the production of lead, as extracted in different countries.

Production and consumption of lead is increasing worldwide. Lead production generally is divided into two major categories, primary and secondary: the primary production is the production from concentrate from the previously mined ores, and the secondary production is the production from scrap. In 2013, 4.74 million metric tons came from the primary production, and 5.74 million tons came from secondary production. The top mining countries for lead in 2013 were China, Australia, Russia, India, Bolivia, Sweden, North Korea, South Africa, Poland, and Ireland. The top lead producing countries were China, United States, India, South Korea, Germany, Mexico, United Kingdom, Canada, Japan, and Australia. According to the International Resource Panel's Metal Stocks in Society report of 2010, the global per capita stock of lead in use in society is 8 kg. Much of this is in more developed countries (20–150 kg per capita) rather than less developed countries (1–4 kg per capita).

Processes of production of primary and secondary lead are similar, despite using different sources of lead—ores and scrap—and some primary production plants now also use scrap, and this trend is likely increase in the future. Given adequate techniques, secondary lead is indistinguishable from primary lead. Scrap lead from the building trade is usually fairly clean and is re-melted without the need for smelting, though some refining operations may be necessary; as such, secondary lead is also cheaper to produce than primary in terms of energy spent on production, often twice or more so.

Primary production

Most lead ores contain only a very low percentage of lead, which must be concentrated during processing. During initial ore processing, ores typically undergo crushing, dense-medium separation, grinding, froth flotation, and drying of the resulting concentrate. The resulting concentrate is the initial quantitative metric of mined lead. Sulfide concentrate is more common for subsequent lead production than oxide concentrate; it commonly has a lead content fraction of 50%–60%, occasionally varying to up to 30% or 80%.

World's largest mining countries of lead, 2015

Country	Output (thousand tons)
China	2,300
Australia	633
United States	385
Peru	300
Mexico	240
India	130
Russia	90
Bolivia	82
Sweden	76
Turkey	54
North Korea	45
Poland	40
South Africa	40
Kazakhstan	38
Ireland	33
Other countries	226

The resulting concentrate is then turned into (impure) lead metal. The main route for doing so is the two-stage process: The sulfide concentrate is roasted in the air, the main reaction occurring is oxidation of lead sulfide with oxygen:

2PbS + 3O₂ → 2PbO + 2SO₂↑

This reaction releases heat once it started. However, as the original concentrate was not pure lead sulfide, roasting does not yield pure oxide, producing primarily lead oxide and a mixture of sulfates and silicates of lead and other metals contained in the ore. This impure lead oxide reduced in a coke-fired blast furnace to the (again, impure) metal by a reaction with that very coke:

2PbO + C → Pb + CO₂↑

Research on a process cheaper in terms of energy spent and pollution introduced into the environment than the described one continues, with some success; a major drawback is that the alternative results in either an exceedingly high sulfur content of the resulting lead metal or too much lead lost as waste. An alternative gaining ground involves direct smelting without an intermediate compound involved; another promising alternative involves hydrometallurgical means (it is based on anodes of impure lead and cathodes of pure lead dissolved in an electrolyte).

Impurities in the resulting metal are still significant; these are mostly 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 drossing, where they float to the top and are skimmed off. Since lead ores contain significant concentrations of silver, the smelted metal also is commonly contaminated with silver. Metallic silver as well as gold is removed and recovered economically by means of the Parkes process, in which zinc is added to lead and adsorbs silver, which dissolves in zinc many times more actively than in lead. 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. Very pure lead can be obtained by processing smelted lead electrolytically by means of the Betts process. The process uses anodes of impure lead and cathodes of pure lead in an electrolyte of silica fluoride. Once electrical potential is applied, impure lead at the anode dissolves and then plates out in the cathode, while the impurities remain in the solution.

Secondary production

Smelting, an essential part of the primary production, is often skipped in the secondary production. The reason for that is that scrap lead itself is commonly reproduced to its metallic form. As such, smelting is only performed when metallic lead had undergone significant chemical transformation, such as oxidation/rusting. However, when smelting is performed, it is performed in a fashion similar to that of the primary production in either a blast furnace or a rotary furnace (though both, with the essential difference being the greater variability of what could be extracted as the final product after the latter). The Isasmemt process is a more recent method that possesses a possibility of extension to the primary production; the essence of this process is that the input battery paste is deprived of its sulfur content (by, for example, treating it with alkalies) and then treated in a coal-fueled furnace in presence of oxygen, which eventually yields impure lead with antimony being the most common impurity.

Refining of secondary lead is similar to that of primary lead; some refining processes may be skipped depending on the material recycled and its potential contamination, with bismuth and silver being skipped especially often of all major impurities.

Of the sources of lead for recycling, lead–acid batteries is the most important one; lead pipe, sheet and cable sheathing are also significant sources.

Applications

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, a small brush used for painting. When the pencil originated as a wrapped graphite writing tool, the particular type of graphite being used was named plumbago (lit. act for lead, or lead mockup).

Elemental form

Lead bricks are commonly used as radiation shielding.

Lead metal has a number of mechanical properties that make using it advantageous in comparison with many alternatives: high density, low melting point, ductility, and relative inertness against oxygen attacks. While many metals are superior to lead in some of these aspects, lead is also more common than most of these metals; moreover, lead minerals are easier to mine and then lead is easier to extract from its ores than many other metals, which makes the resulting metal relatively inexpensive. One disadvantage of using lead, however, is its chemical toxicity, and it has been a reason why lead was or is being phased out for some uses.

Lead has been used for bullets since their invention (see above); however, with the development of firearms, round bullets became pointed and later, lead was jacketed with, for example, copper. 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. Lead is sometimes alloyed with tin or antimony: this increases the cost and time of making the bullet, but increasing the hardness of the bullet, this makes the bullet more effective against hard targets, eases the tension on the gun barrel and does not contaminate it with lead, as simple lead bullets do. However, concerns have been raised over whether lead bullets used for hunting can damage the environment.

Because of its high density and resistance to corrosion, lead is used for the 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 weight belts to counteract the diver's natural buoyancy and that of his equipment.

Roman lead water pipes with taps

Lead pipe in Roman baths

Multicolor lead-glazing in a Tang dynasty Chinese sancai ceramic cup dating from the 8th century CE

Punched lead cast in a Venice bridge wall fixing the hard-metal connecting bar

Lead is alloyed with copper and its alloys (namely, brass and bronze) to increase their machinability and to reduce machine tool wear. Lead does not form a solid solution with copper and is found as granules within copper. It acts as a lubricant in copper; in low concentrations, it also acts as a chip breaker.

It is also 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. 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. It is the traditional base metal of organ pipes, mixed with varying amounts of tin to control the tone of the pipe.

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 balance the wheels of a car; this use is being phased out in favor of other materials for environmental reasons.

Apart from its mechanical properties, lead is also useful in batteries, namely lead–acid batteries. The reactions in the battery between lead, lead dioxide, and sulfuric acid provides a reliable source of voltage. This, since lead in batteries undergoes no direct contact with humans (and thus no toxicity), is a use not threatened by toxicity concerns, and has been the largest use of lead in early 21st century.

Lead is also used as electrodes in the process of electrolysis. It is used in solder for electronics, although this usage is being phased out by some countries to reduce the amount of environmentally hazardous waste, and 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. It is also used as shielding from radiation (e.g., in X-ray rooms). Molten lead is used as a coolant (e.g., for lead cooled fast reactors).

=Ancient lead special use

Lead when mined contains an unstable isotope, lead-210, which has a half life of 22 years. This makes lead slightly radioactive. As such ancient lead which has almost no radioactivity is sometimes desired for scientific experimentation.

Compounds

Lead compounds are used as a coloring element in ceramic glazes, notably in the colors red and yellow.

Lead tetraacetate (LTA) and lead dioxide have been used as oxidizing agents in organic chemistry. Geminal diols are cleaved to a pair of carbonyl compounds by stoichiometric LTA. LTA also is a selective oxidant of 5-methyl groups in 5-methylpyrrole-2-carboxylic esters, leading to 5-acetoxymethyl groups or 5-formyl groups with one or two equivalents of oxidant, respectively, to provide important intermediates for porphyrin synthesis.

Lead is frequently used in polyvinyl chloride (PVC) plastic, which coats 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 alternatives such as zinc. Lead glass is composed of 12–28% lead oxide. It changes the optical characteristics of the glass and reduces the transmission of ionizing radiation.

Some artists using oil-based paints continue to use lead carbonate white, citing its properties in comparison with the alternatives. Tetraethyl 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.

Biological and environmental effects

Main article: Lead poisoning

Biological

Symptoms of lead poisoning.

Lead is a highly poisonous metal (whether inhaled or swallowed), affecting almost every organ and system in the body. The component limit of lead (1.0 μg/g) is a test benchmark for pharmaceuticals, representing the maximum daily intake an individual should have. Even at this level, a prolonged intake can be hazardous to human beings. Exposure to lead and lead chemicals occurs primarily through ingestion, to a lesser extent through inhalation and occasionally by direct contact.

The primary cause of lead's toxicity is its interference with a variety of enzymes because it binds to sulfhydryl groups found on many enzymes. Part of lead's toxicity results from its ability to mimic other metals that take part in biological processes, which act as cofactors in many enzymatic reactions, displacing them at the enzymes on which they act. Lead salts are thus very quickly and efficiently absorbed by the body, accumulating in it and leading to both chronic and acute poisoning. Lead is able to bind to and interact with many of the same enzymes as these metals but, due to its differing chemistry, does not properly function as a cofactor, thus interfering with the enzyme's ability to catalyze its normal reaction or reactions. Among the essential metals with which lead interacts are calcium, iron, and zinc. Thus high levels of calcium and iron tend to protect one somewhat from lead poisoning, while low levels of these metals render one more susceptible.

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. 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 ethylenediaminetetraacetic 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. According to the Agency for Toxic Substance and Disease Registry, a small amount of ingested lead (1%) will store itself in bones, and the rest will be excreted by an adult through urine and feces within a few weeks of exposure. However, only about 32% of lead will be excreted by a child.

Ingestion of lead-based 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. 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 issued the regulation in 1980. The use of lead for water pipes is problematic in areas with soft or (and) acidic water. Hard water forms insoluble layers in the pipes while soft and acidic water dissolves the lead pipes.

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.

Dermal exposure may be significant for a narrow category of people working with organic lead compounds, but is of little concern for general population, as most countries stopped using leaded gasoline by 2007. The rate of skin absorption is also low for inorganic lead.

The main target for lead toxicity is the nervous system, both in adults and children, in which it crosses the blood-brain barrier by mimicking calcium. Lead causes loss of neurons' myelin sheaths, reduces numbers of neurons, interferes with neurotransmission, and decreases neuronal growth. In a child's developing brain, lead interferes with synapse formation in the cerebral cortex, neurochemical development (including that of neurotransmitters), and organization of ion channels. Long-term exposure of adults can result in decreased performance in some tests that measure functions of the nervous system. Long-term exposure to lead or its salts (especially soluble salts or the strong oxidant PbO₂) can cause nephropathy, and colic-like abdominal pains. 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 cause severe damage to 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 has been shown to reduce fertility in males. Lead also damages nervous connections (especially in young children) and causes 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. 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. The treatment for lead poisoning consists of dimercaprol and succimer.

NFPA 704 "fire diamond"
1 3 0
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). Most cases of adult elevated blood lead levels are workplace-related. High blood levels are associated with delayed puberty in girls. Lead has been shown many times to permanently reduce the cognitive capacity of children at extremely low levels of exposure.

Despite the toxicity of lead in significant amounts, there is some evidence that trace amounts of lead are beneficial in pigs and rats, and that its absence causes deficiency signs including depressed growth, anemia, and disturbed iron metabolism. If true in humans as well, this would make lead by far the heaviest essential element, since its atomic number (82) is much greater than that of the second-heaviest such element, iodine (element 53). Nevertheless, these findings are still uncertain, and even if lead does turn out to be beneficial in small quantities, the threshold of toxicity is so low that lead toxicity would remain a much higher priority to address than lead deficiency.

Environmental

The extraction, production, use and disposal of lead and its products have caused significant contamination of the Earth's soils and waters, posing a hazard to living organisms because of its toxicity. Atmospheric emissions of lead were at their peak during the Industrial Revolution and the period of leaded petrol in the second half of the twentieth century; although these periods are over, elevated concentrations of lead persist in soils and sediments in post-industrial and urban areas. Meanwhile, industrial emissions continue in many parts of the world.

Remediation

Fish bones are being researched for their ability to bioremediate lead in contaminated soil. The fungus Aspergillus versicolor is both greatly effective and fast at removing lead ions. Several bacteria have been researched for their ability to reduce lead; including the sulfate reducing bacteria Desulfovibrio and Desulfotomaculum; which are highly effective in aqueous solutions.

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 tonnes in 1990 to 47.5 tonnes in 1995, two years after the ban.

Restriction of lead usage

During the 20th century, the use of lead in paint pigments was sharply reduced because of the danger of lead poisoning, especially to children. 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 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 Chinese brass. Old 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. Old paint should not be stripped by sanding, as this produces inhalable dust.

People can be exposed to lead in the workplace by breathing it in, swallowing it, skin contact, and eye contact. In the United States, the Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for lead exposure in the workplace as 0.050 mg/m³ over an 8-hour workday, which applies to metallic lead, inorganic lead compounds, and lead soaps. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 0.050 mg/m³ over an 8-hour workday, and recommends that workers' blood concentrations of lead stay below 0.060 mg per 100 g blood. At levels of 100 mg/m³, lead is immediately dangerous to life and health.

See also

• 2009 Chinese lead poisoning scandal
• Adult Blood Lead Epidemiology and Surveillance
• Consumer Product Safety Improvement Act
• Devon colic
• Flint water crisis
• Medical geology
• Plumbosolvency
• Restriction of Hazardous Substances Directive
• Roman lead pipe inscription

Notes

References

Bibliography

• Rieuwerts, John (2015). "Chapter 13. Lead". The Elements of Environmental Pollution. Abingdon, UK: Routledge. pp. 224–34. ISBN 9780415859202. 
• Bisson, Michael S.; Vogel, Joseph O. (2005). Ancient African Metallurgy: The Sociocultural Context. Rowman & Littlefield. ISBN 978-0-742-50261-1. 
• Sutherland, Charles A.; Milner, Edward F.; Kerby, Robert C.; Teindl, Herbert; Melin, Albert; Bolt, Hermann M. (2005). "Lead". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a15_193.pub2. ISBN 3-527-30673-0. 
• Lide, D. R., ed. (2004). CRC Handbook of Chemistry and Physics (84th ed.). CRC Press. ISBN 978-0-8493-0484-2. 
• Greenwood, N. N.; Earnshaw, A. (1998). Chemistry of the Elements (2nd ed.). Butterworth Heinemann. ISBN 0-7506-3365-4. 
• Kroonen, Guus (2013). Etymological Dictionary of Proto-Germanic. Leiden Indo-European Etymological Dictionary Series. Leiden, Boston: Brill. 
• Rich, Vincent (1994). The International Lead Trade. Woodhead Publishing. ISBN 9781855731035. 
• Polyanskiy, N. G. (1986). Fillipova, N. A, ed. Аналитическая химия элементов: Свинец [Analytical Chemistry of the Elements: Lead] (in Russian). Nauka. 
• Thornton, Iain; Rautiu, Radu; Brush, Susan (2001). Lead: the facts. Hersham, Surrey: Ian Allan Printing. ISBN 0-9542496-0-7. 

Further reading

• Keisch, B.; Feller, R. L.; Levine, A. S.; Edwards, R. R. (1967). "Dating and Authenticating Works of Art by Measurement of Natural Alpha Emitters". Science. 155 (3767): 1238–1242. Bibcode:1967Sci...155.1238K. doi:10.1126/science.155.3767.1238. PMID 17847535. 
• Keisch, B (1968). "Dating Works of Art Through their Natural Radioactivity: Improvements and Applications". Science. 160 (3826): 413–415. Bibcode:1968Sci...160..413K. doi:10.1126/science.160.3826.413. PMID 17740234. 
• Keisch, B (1968). "Discriminating Radioactivity Measurements of Lead: New Tool for Authentication". Curator. 11 (1): 41–52. doi:10.1111/j.2151-6952.1968.tb00884.x. 
• Casas, Jose S.; Sordo, Jose, eds. (2006). Lead Chemistry, Analytical Aspects. Environmental Impacts and Health Effects. Elsevier. ISBN 0-444-52945-4. 

External links

• National Lead Free Wheel Weight Initiative| Waste Minimization|Wastes|US EPA
• CDC – NIOSH Pocket Guide to Chemical Hazards – Lead

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