P. 1 

# OAR Box 

# 1131 Prepped by Ollie Stewart



## Document

Number: 

# 116)11-1-12 1 Docket Number: 

# A-83-2 2

Printed 4/21/2008 2:34:11 PM

Sheet 116 of 162

# £ P. 2 j , m. —' , —«

k 

# -x - 

# izt EP A 600/ 8 7 7 01

7 Decembe r197

7 Specia l Serie s



# Ai rQuality 

# Criteriafo

r WDEJ I

Offic e o f Researc h an d Developmen t " U.S . Environmenta l Protectio n Agenc y ; 

### -egg ?

Washington , D.C . 2046 0 'T^ TP. 3



## RESEARC H REPORTIN GSERIE S Researc hreport s o f

th e Offic e o f

Researc han dDevelopment , U.S . Environmenta l Protectio n Agenc y hav e bee n groupe dint o series . Thes e broa dcategorie s wer e establishe dt o facilitat e furthe r developmen t

an dapplicatio n o f

environmenta l technology . Eliminatio n of traditiona l groupin g wa s consciousl y planne dt o foste r technolog y transfe r

an damaximu minterfac e i n relate dfields . Thes e serie s are :

1 . Environmenta l Healt hEffect s Researc h 2 . Environmenta l Protectio n Technolog y 3 . Ecologica l Researc h 4 . Environmenta l Monitorin g 5 . Socioeconomi c Environmenta l Studie s 6 . Scientifi c an dTechnica l Assessmen t Report s (STAR ) 7 . Interagenc y Energy-Environmenta l Researc han dDevelopmen t 8 . "Special " Report s 9 . Miscellaneou s Report s Thi s repor t

ha s bee n assigne dt o th e SPECIA Lseries . Ai r qualit y criteri adocument s ar e issued , a s mandate db y th e Clea n Ai r Act , t o provid e th e basi s fo r decision s b y th e Administrator , EPA , regardin g th e nee dfo r nationa l ambien t

ai r qualit y standards . 

## EP A REVIE WNOTIC E Thi s repor t

ha s bee n reviewe db y th e Offic e o f Researc han dDevelopment , EPA , an dapprove dfo r publication . Mentio n o f trad e name s o r

commercia l product s doe s no t constitut e endorsemen t o r recommendatio n fo r

use . 

## AVAILABILIT Y NOTIC E Thi s documen t

i s availabl e throug hth e Librar y Service s Office , MD-35 , Researc hTriangl e Park , N.C . 27711 . Th e printe dversio n wil l als o b e availabl e fro mth e Superintenden t o f Documents , U.S . Governmen t

Printin g Office , Washington , D.C . 20402 .



## Publicatio n No . EPA-600/8-77-01 7P. 4



### EPA-600/8-77-01 7 December197 7



# AI RQUALIT Y CRITERI A

FO R LEA D

U.S . ENVIRONMENTA L PROTECTIO N AGENC Y OFFICE OF RESEARC H AN D DEVELOPMEN T

WASHINGTON , D.C . 2046 0 Fo rsal e b y th e Superintenden to f Documents' , U.S . Governmen t Printin g Office , Washington , D.C . 2040 2P. 5



# PREFACE Thi s documen t

ha s bee n prepare dpursuan t t o Sectio n108(a)(2 ) o f th e Clea n Ai r Act , a s amended , an dth e Administrator' s actio no nMarc h31,1976 , o f listin g lea d a s acriteri apollutant . Unde r th e Act , th e issuanc e o f ai r qualit y criteri ai s avita l ste p in aprogra mo f

responsibl e technological , social , an dpolitica l actio n t o pro tec t th e publi c fro mth e advers e effect s o f ai r pollution . Thes e healt han dwelfar e criteri afulfil l th e regulator y purpos e o f servin g a s th e basi s upo n whic hth e Administrato r mus t promulgat e nationa l primar y an dsecond ar y ambien t

ai r qualit y standard s fo r

lea dunde r

Sectio n10 9 o f

th e Clea n Ai r

Act . Th e propose dstandard s ar e bein g publishe dconcurrentl y wit hth e publicatio n o f thi s criteri adocument . Althoug hth e preparatio no f acriteri adocumen t

require s acomprehensiv e revie w an devaluatio n o f th e curren t

scientifi c knowledg e regardin g th e ai r pollu tan t in question , th e documen t doe s no t

constitut e acomplete , in-dept hscientifi c review . Th e reference s cite dd o no t constitut e acomplet e bibliography . Th e objec tiv e i s t o evaluat e th e scientifi c dat abas e an dt o formulat e criteri awhic hma y serv e a s th e basi s fo r

decision s regardin g th e promulgatio n o f anationa l ambien t

ai r qualit y standar dfo r

lead . I n th e cas e o f

lead , a s wel l a s othe r

ai r pollutants , advers e healt heffect s ar e a consequenc e o f

th e tota l bod y burde nresultin g fro mexposur e vi aal l route s o f in take . I t i s necessary , therefore , t o evaluat e th e relativ e contributio n mad e b y in halatio n an dingestio n o f atmospheri c lea dt o th e tota l bod y burden . Th e Agenc y i s please dt o acknowledg e th e effort s an dcontribution s o f al l per sons ' an dgroup s wh o hav e participate da s author s o r reviewer s t o thi s document . I n th e ias t analysis , however , th e Environmenta l Protectio nAgenc y i s responsibl e fo r it s content .

DOUGLA S M . COSTL E Administrato r U.S . Environmenta l Protectio n Agenc y

i nP. 6



## ABSTRAC T Thi s document

summarize s curren t

knowledg e abou t

th e relationship s o

f air born e leadt o ma

n an dhi s environment . Th e effects that hav e bee n observe dt o oc cur whe n airborn e leadha s reache dor exceede dspecifi c level s fo r specifi c time period s constitut e th e centra l criteri ao n whichEP

A will bas e anational ambient air quality standar dfo

r lead . Althoug hthi s document

deal s mainl y wit

hairborn e lead , i

t als o outline s othe r environmental route s o

f exposure . Primary exposure t o airborn e lea doccur s directl y vi ainhalation , andit s source s ar e relativel y eas y t o identify . Secondar y ex posure ma y occur throug hingestio n o

f food s fro mcrop s contaminate db

y airborn e leador , especiall y i

n children , throug hmouthin g o f nonfoo ditem s an dmaterial s s o contaminated . Exposure s t o nonairborn e leadma y als o b e direc t

andindirect , and route s includ e ingestio n o

f food s containin g leadattributabl e t o natura l uptake and t o processing . In man , leadprimaril y affects re dbloo dcells , th e centra l andperiphera l nervou s systems , sof

t tissue s suc

ha s liver andkidney , andbone ; th e latte r ultimatel y se quester s 9 5 percent

o f th e body' s leadburden . Significan t biological indice s o

f ex posure t o leadinclud e microgra mquantitie s o

f leadando

f erythrocyt e pro toporphyri n (EP ) per

decilite r o f bloo d(/xg/dl) . Advers e effects rang e fro mele vate dE Pandmil danemi aa t 20 t o 4 0 fig Pb/dl—throug hgastrointestinal , renal , an dhepati c pathologies—to severe neurobehaviora l impairment a t >8 0 t o 120 fig Pb/dl , sometime s culminatin g a t thos e level s i

n convulsion s andabrup t death . Preschoo l childre n anddevelopin g fetuse s ar e th e population s a t greates t risk .

I V

## SCIENC E ADVISOR Y BOAR D SUBCOMMITTE E O N SCIENTIFI C CRITERI A FO RENVIRONMENTA L LEA D P. 7 

# 1

Th e substanc e o f

thi s documen t

wa s revie w b y aSubcommitte e o n Scientifi c Cri teri afo r Environmenta l Lead , Scienc e Advisor y Board , inpubli c session . CHAIRMAN : Dr . Roge r

O . McClellan , Directo r o f Inhalatio n Toxicolog y Researc hInstitute , Lovelac e Foundation , P.O . Bo x 5890 , Albuquerque , Ne w Mexic o 8711 5 CONSULTANTS : Dr . J . Julia n Chisolm , Jr. , Senio r Staf f Pediatrician , Baltimor e Cit y Hospital , 494 0 Easter n Avenue , Baltimore , Marylan d21224 ; an dAssociat e Professo r o f Pediatrics , John s Hopkin s Universit y Schoo l o f Medicin e Dr . Pau l B . Hammond , Professo r o f Environmenta l Health , Departmen t o f En vironmenta l Health , Universit y o f Cincinnat i Medica l Center , 322 3 Ede n Avenue , Cincinnati , Ohi o 4526 7 Dr . Jame s G . Horsfall , Directo r Emeritus , Departmen t o f Plan t Patholog y an d Botany , Connecticu t

Agricultur e Experimen t Station , Ne w Haven , Connecti cu t 0650 4 MEMBERS : Dr . Samue l S . Epstein , Professo r o f Occupationa l an dEnvironmenta l Medicine , Schoo l o f

Publi c Health , Universit y o f Illinois , P.O . Bo x 6998 , Chicago , Il linoi s 6068 0 Dr . Edwar dF . Ferrand , Assistan t Commissione r

fo r Science s an dTechnology , Ne w Yor k

Cit y Dept . fo r

Ai r Resources , 5 1 Asto r

Place , Ne w York , Ne w Yor k 1000 3 Dr . Sheldo n K . Friedlander , Professo r o f Chemica l Engineerin g an dEnviron menta l Healt hEngineering , W . M . Kec k Laboratory , Californi aInstitut e o f Technology , Pasadena , Californi a9110 9 Dr . Jennife r

L . Kelsey , Associat e Professo r o f Epidemiology , Yal e Universit y Schoo l o f Medicine , Departmen t

o f Epidemiolog y an dPubli c Health , 6 0 Col leg e Street , Ne w Haven , Connecticu t 0650 4 Dr . Rut hLevine , Chairman , Graduat e Divisio no f Medicin e an dDentistry , Bosto n Universit y Colleg e o f Medicine , Boston , Massachusett s 0211 8 Mailin g address : 21 2 Craft s Road , Chestnu t Hill , Brookline , Massachusett s 0216 7 Dr . Bailu s Walker , Jr. , Director , Environmenta l Healt hAdministration , Depart men t o f Environmenta l Services , Governmen t o f th e Distric t

o f Columbia , 80 1 Nort hCapitol , NE , Washington , D.C . 2000 2 STAF F OFFICER : Mr . Erns t

Linde , Scientis t

Administrator , Scienc e Advisor y Board , U.S . Environ menta l Protectio n Agency , Crysta l Mal l Buildin g 2 , 192 1 Jefferso n Davi s Highway , Arlington , Virgini a2046 0P. 8



## CONTRIBUTOR S AN D REVIEWER S Mr . Geral dG . Akland , Environmenta l Monitorin g an dSuppor t Laboratory , En vironmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . C . Ale x Alexander , Adjunc t Professo r

o f Medicin e an dChie f

o f Hospita l Medica l Staff

, Schoo l o f

Medicine , Wrigh t

Stat e University , Dayton , Ohi o 4543 1 Dr . A . P . Altshuller , Director , Environmenta l Science s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . Ann aBaetjer , Professo r Emeritu s o f

Environmenta l Medicine , Departmen t o f Environmenta l Medicine , Schoo l o f Hygien e an dPubli c Health , Th e John s Hopkin s University , 61 5 Nort hWolf e Street , Baltimore , Marylan d2120 5 Dr . Donal dBarltrop , Pediatric s Unit , St . Mary' s Hospita l Medica l School , Lon do n W 2 1PG , Englan d Ms . Gayl aBenignus , Technica l Consultant , Researc hTriangl e Park , Nort h Carolin a2770 9 Dr . Irwi n H . Billick , Progra mManager , Lead-Base dPain t Poisonin g Preventio n Research , Divisio n o f

Housin g Research , Offic e o f th e Assistan t

Secretar y fo r Polic y Developmen t

an dResearch , Departmen t o f Housin g an dUrba n Development , Washington , D.C . 2041 0 Dr . Rober t

P . Botts , Environmenta l Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , 20 0 S W35t h Street , Corvallis , Orego n 9733 0 Dr . Rober t

Bornschein , Departmen t o f Environmenta l Health , Colleg e o f Medicine , Universit y o f Cincinnati , Cincinnati , Ohi o 4526 7 Dr . Ronal dL . Bradow , Environmenta l Science s Researc hLaboratory , Environ menta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc h Triangl e Park , Nort hCarolin a2771 1 Dr . Kennet hBridbord , Director , Offic e o f Extramura l Coordinatio n an dSpecia l Projects , Nationa l Institut e fo r Occupationa l Safety an dHealth , 560 0 Fisher s Lane , Rockville , Marylan d2085 2 Dr . Marijo n Bufalini , Environmenta l Science s Researc hLaboratory , Environ menta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc h Triangl e Park , Nort hCarolin a2771 1 Dr . Rober t

Burger , Senio r

Scientist , Researc hTriangl e Institute , P.O . Bo x 12194 , Researc hTriangl e Park , Nort hCarolin a2770 9 Dr . Joh n B . Clements , Environmenta l Monitorin g an dSuppor t Laboratory , En vironmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Mr . Stanto n Coerr , Strategie s an dAi r Standard s Division , Offic e o f Ai r Qualit y Plannin g an dStandards , U.S . Environmenta l Protectio nAgency , Researc h Triangl e Park , Nort hCarolin a2771 1Ms . Josephin e S . Cooper , Strategie s an dAi r Standard s Division , Offic e o f Ai r Qualit y Plannin g an dStandards , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Mr . Gunthe r

F . Craun , Healt hEffect s Researc hLaboratory , U.S . Environmenta l Protectio n Agency , Cincinnati , Ohi o 4526 8 Dr . Annemari e Crocetti , Professo r o f Epidemiology , Ne w Yor k Medica l College , Ne w York , Ne w Yor k

1002 9 Dr . Terr i Damstra , Offic e o f Healt hHazar dAssessment , Nationa l Institut e o f Environmenta l Healt hServices , Researc hTriangl e Park , Nort hCarolin a 2770 9 Dr . Clif f Davidson , Graduat e Researc hAssistant , Californi aInstitut e o f Tech nology , Mai l Sto p 138-78 , Pasadena , Californi a9110 9 Dr . Iva n Diamond , Departmen t o f Neurology , Schoo l o f

Medicine , Universit y o f California , San Francisco , Californi a9414 3 Dr . Michae l Dowe , Jaycor , Incorporated , Researc hTriangl e Park , Nort h Carolin a2770 9 Dr . Be n B . Ewing , Professo r an dDirector , Institut e fo r Environmenta l Studies , Universit y o f

Illinois , 40 8 S . Goodwi n Avenue , Urbana , Illinoi s 6180 1 Dr . Harol dFurst , Professo r o f Epidemiology , Ne w Yor k Medica l Colleg e an d Ne w Yor k

Cit y Healt hDepartment , Ne w York , Ne w Yor k 1002 9 Mr . Warre n Galke , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio nAgency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . J.H.B . Garner , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . Joh n T . Gatzy , Associat e Professo r o f Pharmacology , Schoo l o f Medicine , Universit y o f

Nort hCarolina , Chape l Hill , Nort hCarolin a2751 4 Dr . Rober t

Goyer , Departmen t

o f Pathology , Universit y o f Wester n Ontario , Londo n 72 , Ontario , Canad a Dr . Leste r

D . Grant , Associat e Professo r o f Psychiatry , Schoo l o f Medicine , Universit y o f

Nort hCarolina , Chape l Hill , Nort hCarolin a2751 4 Mr . Danie l Greathouse , Healt hEffect s Researc hLaboratory , U.S . Environmen ta l Protectio n Agency , Cincinnati , Ohi o 4526 8 Dr . Vi c Hasselblad , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . Dere k

Hodgson , Professor , Departmen t o f Chemistry , C44 8 Kenan , Univer sity o f Nort hCarolina , Chape l Hill , Nort hCarolin a2751 4 Dr . Joh n Horn , Environmenta l Consultant , 75 8 Oxfor dStreet , West , London , Ontario , Canad aN6M1V 2 Dr . Rober t

J . M . Horton , Senio r Researc hAdvisor , Healt hEffect s Researc h Laboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Mr . Alle n G . Hoyt , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . F . Gordo n Hueter , Associat e Director , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . Emmet t

S . Jacobs , Divisio nHead , Additive s an dEnvironmenta l Studies , E . I . d u Pon t

d e Nemour s an dCompany , Inc. , Petroleu mLaboratory , Wilmington , Delawar e 1989 8

v n^ p i n

Mr . Gar y L . Johnson , Industria l Environmenta l Researc hLaboratory , Environ menta l Researc hCenter , U.S . Environmenta l Protectio nAgency , Researc h Triangl e Park , Nort hCarolin a2771 1 Mr . Rober t

Kellam , Strategie s an dAi r Standard s Division , Offic e o f Ai r Qualit y Plannin g an dStandards , U.S . Environmenta l Protectio n Agency , Researc h Triangl e Park , Nort hCarolin a2771 1 Dr . Carol e A . Kimmel , Nationa l Cente r fo r Toxicologica l Research , Jefferson . Arkansa s 7207 9 Dr . Rober t

R . Kinnison , Environmenta l Monitorin g an dSuppor t Laboratory , U.S . Environmenta l Protectio nAgency , P.O . Bo x 15027 , La s Vegas , Nevad a 8911 4 Dr . Joh n H . Knelson , Director , Healt hEffect s Researc hLaboratory , Environ menta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc h Triangl e Park , Nort hCarolin a2771 1 Dr . Marti n R . Krigman , Professo r o f Pathology , Schoo l o f

Medicine , Universit y o f Nort hCarolina . Chape l Hill , Nort hCarolin a2751 4 Dr . Rober t

E . Lee , Deput y Director , Healt hEffect s Researc hLaboratory , En vironmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . G . J . Love , Epidemiolog y Consultant , Researc hTriangl e Park , Nort h Carolin a2770 9 Dr . Jame s MacNeill , Pediatrician , Hillsid e Medica l Center , E l Paso , Texa s 7990 3 Dr . Kathry n R . Mahaffey . Divisio no f Nutrition . Foo dan dDru g Administration , Departmen t

o f Health , Educa t

ion . an dWelfare , 109 0 Tusculu mAvenue , Cincinnati . Ohi o 4522 6 Dr . Ale c E . Martin , Visitin g Scientist , Offic e o f Healt hHazar dAssessment , Na tiona l Institut e o f

Environmenta l Healt hSciences , P.O . Bo x 12233 , Researc h Triangl e Park , Nort hCarolin a2770 9 Dr . Edwar dB . McCabe . 322 5 Knollwoo dWay . Madison , Wisconsi n 5371 3 Mr . Gar y D . McCutchen , Emissio nStandard s an dEngineerin g Division , Offic e o f Ai r Qualit y Plannin g an dStandards , U.S . Environmenta l Protectio n Agen cy , Researc hTriangl e Park , Nort hCarolin a2771 1 Mr . Thoma s B . McMullen , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio nAgency , Researc hTriangl e Park , Nort hCarolin a2771 1 Mr . Josep hMerenda . Offic e o f Mobil e Sourc e Ai r

Pollutio n Control , Offic e o f Ai r an dWast e Management , U.S . Environmenta l Protectio n Agency , Wash ington , D.C . 2046 0 Ms . Margarit aM . Morrison , Technica l Informatio n Specialist , Progra mOpera tion s Office , Healt hEffect s Researc hLaboratory , Environmenta l Researc h Center , U.S . Environmenta l Protectio nAgency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . Pau l Mushak , Associat e Professo r o f Pathology , Schoo l o f

Medicine , Univer sity o f Nort hCarolina , Chape l Hill , Nort hCarolin a2751 4 Dr . D . F . Nataush , Professo r o f Chemistry , Colorad o Stat e University , For t Col lins , Colorad o 8052 3 Dr . Joh n C . Nduaguba , Assistan t Professo r

o f Medicine , Schoo l o f

Medicine , Wrigh t Stat e University , Dayton , Ohi o 4543 1 Dr . Herber t

L . Needleman , Th e Children' s Hospita l Medica l Center , 30 0 Long woo dAvenue , Boston , Massachusett s 0211 5 Dr . Stat aNorton , Departmen t o f Pharmacology , Universit y o f Kansa s Medica l Center , Kansa s City , Kansa s 6611 0 vii iP.1 1

Mr . Joh n O'Connor , Strategie s an dAi r Standard s Division , Offic e o f Ai r Qualit y Plannin g an dStandards , U.S . Environmenta l Protectio nAgency , Researc h Triangl e Park , Nort hCarolin a2771 1 Dr . Sergi o Piomelli , Professo r o f Pediatric s an dDirecto r o f Pediatri c Hematology , Schoo l o f

Medicine , Ne w Yor k

Universit y Medica l Center , 55 0 Firs t Avenue , Ne w York , Ne w Yor k 1001 6 Dr . Herber t

Posner , Offic e o f

Healt hHazar dAssessment , Nationa l Institut e o f Environmenta l Healt hSciences , Researc hTriangl e Park , Nort hCarolin a 2770 9 Dr . Jerr y Ptasnik , Directo r o f Specia l Education , E l Pas o Cit y Schools , E l Paso , Texa s 7990 3 Dr . Michae l J . Quigley , Healt hEffect s Consultant , Researc hTriangl e Park , Nort hCarolin a2770 9 Dr . Ketura hReinbold , Associat e Researc hBiologist , Institut e fo r Environmenta l Studies , Universit y o f

Illinois , 40 5 S . Goodwi nAvenue , Urbana , Illinoi s 6180 1 Dr . Lawrenc e Reiter , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio nAgency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . Joh n F . Rogers , Assistan t Professo r

o f Medicine , Schoo l o f Medicine , Universit y o f

Nort hCarolina , Chape l Hill , Nort hCarolin a2751 4 Dr . Gar y L . Rolfe , Associat e Professo r o f Forestry , Institut e fo r

Environmenta l Studies , Universit y o f

Illinois , 40 8 S . Goodwi n Avenue , Urbana , Illinoi s 6180 1 Dr . Donal dRouth , Professo r o f Clinica l Psychology , Schoo l o f Medicine , Universit y o f

Nort hCarolina , Chape l Hill , Nort hCarolin a2751 4 Mr . Rober t

C . Ryans , Writer-Editor , Environmenta l Researc hLaboratory , U.S . Environmenta l Protectio nAgency , Colleg e Statio nRoad , Athens , Georgi a 3060 5 Mr . Edwar dA . Schuck , Environmenta l Monitorin g an dSuppor t Laboratory , U.S . Environmenta l Protectio nAgency , P.O . Bo x 15027 , La s Vegas , Nevad a 8911 4 Dr . R . K . Skogerboe , Professo r o f Chemistry , Colorad o Stat e University , For t Collins , Colorad o 8052 3 Dr . Ceci l Slome , Professo r o f Epidemiology , Schoo l o f Publi c Health , Universit y o f Nort hCarolina , Chape l Hill , Nort hCarolin a2751 4 Mr . Jame s R . Smith , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio nAgency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . R . D . Snee , Biostatistician , E . I . d u Pon t d e Nemour s an dCompany , Inc. , Petroleu mLaboratory , Wilmington , Delawar e 1989 8 Mr . Andre w G . Stead , Statistician , Healt hEffect s Researc hLaboratory , Environ menta l Researc hCenter , U.S . Environmenta l Protectio nAgency , Researc h Triangl e Park , Nort hCarolin a2771 1 Mr . Ori n W . Stopinski , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Dr . Richar dJ . Thompson , Environmenta l Monitorin g an dSuppor t Laboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 Ms . Beverl y E . Tilton , Healt hEffect s Researc hLaboratory , Environmenta l Researc hCenter , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , Nort hCarolin a2771 1 I XP.1 2 *********



### Mr . Ia n von Lindern , Environmental Engineer , Departmen t o f Healthan d Welfare , Divisio n o

f th e Environment , State o f Idaho , 32

4 2n dStreet , East , Twin Falls , Idah o 8330 1 Ms . P . A . Warrick , Technical Consultant , Schoo l o f Publi c Health , Universit

y o f Nort hCarolina , Chape l Hill , Nort hCarolin a2754 1 Mr . Tony Yankel , Divisio n o f th e Environment , Departmen t o f Healthan d Welfare , Statehouse , Boise , Idah o 8372 0 Dr . R . L . Zielhuis , Universitei t von Amsterdam , Corone l Laboratorium , Eerst e Constantij n Huygersstcaa

t 20 , Amsterdam , Netherland s Dr . R . L . Zimdahl , Professor o f Botany an dPlant

Pathology , Colorad o State University , Fort

Collins , Colorad o 8052 3

# CONTENT S

Paiie PREFAC Eii i ABSTRAC T iv SCIENTIFI C ADVISOR Y BOAR D SUBCOMMITTE EO N SCIENTIFI C CRITERI A FO RENVIRONMENTA LLEA D v CONTRIBUTOR S AN D REVIEWER S v i FIGURE S xv i TABLE S xi x ABBREVIATION S AN D SYMBOL S xxii i 1 . SUMMAR Y AN D CONCLUSION S 1- 1 1. 1 Introductio n 1- 1 1.1. 1 Potentia l Exposur e t o Environmenta l Lea d1- 1 1.1. 2 Source s o f

Environmenta l Lea d1-2 1.1. 3 Monitorin g o f

Environmenta l Lea d1- 3 1. 2 Effect s o f

Lea do n Ma n an dHi s Environmen t 1- 4 1.2. 1 Effec t

o f Lea do n Ma n1- 4 1.2. 2 Effect s o f

Lea do nth e Ecosyste m1- 9 1. 3 Effect s o f

Lea do n Population s 1-1 0 1. 4 Assessmen t

o f Ris k fro mHuma n Exposur e t o Lea d1-1 1 1.4. 1 Us e o f

Blood-Lea dLevel s in Ris k Assessmen t

1-1 1 1.4. 2 Us e o f

Biologica l an dAdvers e Healt hEffect s o f Lea din Ris k Assessmen t

1-1 2 1.4. 3 Population s at

Ris k 1-1 4 2 . INTRODUCTIO N 2- 1 3 . CHEMICA LAN D PHYSICA LPROPERTIE S 3- 1 3. 1 Elementa l Lea d3- 1 3. 2 Genera l Chemistr y o f Lea d3- 1 3. 3 Organometalli c Chemistr y o f Lea d3- 2 3. 4 Comple x Formatio n an dChelatio n3- 2 3. 5 Reference s fo r

Chapte r 3 3- 4 4 . SAMPLIN GAN D ANALYTICA LMETHOD S FO RLEA D 4- 1 4. 1 Introductio n 4- 1 4. 2 Samplin g 4- 2 4.2. 1 Sample r

Sit e Selectio n4- 2 4.2. 2 Samplin g Error s 4- 2 4.2. 3 Samplin g fo r

Airborn e Particulat e Lea d4- 3 4.2. 4 Samplin g fo r

Vapor-Phas e Organi c Lea dCompounds . . 4- 4 4.2. 5 Samplin g fo r

Lea din Othe r

Medi a4- 4 4.2. 6 Sourc e Samplin g 4- 6 4.2. 7 Filte r

Selectio nan dSampl e Preparatio n4- 7

X IP.1 4

4. 3 Analysi s 4- 8 4.3. 1 Colorimetri c Analysi s 4- 8 4.3. 2 Atomi c Absorptio nAnalysi s 4- 8 4.3. 3 Anodi c Strippin g Voltammetr y 4- 9 4.3. 4 Emissio n Spectroscop y 4- 9 4.3. 5 Electro n Microprob e 4-1 0 4.3. 6 X-Ra y Fluorescenc e 4-1 0 4.3. 7 Method s f©

r Compoun dAnalysi s 4-1 1 4. 4 Conclusion s 4-1 1 4. 5 Reference s fo r

Chapte r 4 4-1 1 5 . SOURCE S AN D EMISSION S 5- 1 5. 1 Natura l Source s 5- 1 5. 2 Man-Mad e Source s 5- 1 5.2. 1 Productio n 5- 1 5.2. 2 Utilizatio n 5- 1 5.2. 3 Emission s 5- 2 5. 3 Reference s fo r

Chapte r 5 5- 5 6 . TRANSFORMATIO N AN D TRANSPOR T 6- 1 6. 1 Introductio n 6- 1 6. 2 Physica l an dChefiica l Transformation s inth e Atmospher e .. . 6- 1 6.2. 1 Physica l Transformation s 6- 1 6.2. 2 Chemica l Transformation s 6- 4 6. 3 Transpor t

in Ai r 6- 8 6.3. 1 Distributio n Mechanism s 6- 8 6.3. 2 Remova l Mechanism s 6-1 2 6.3. 3 Model s 6-1 9 6. 4 Transformatio n an dTranspor t in Othe r

Environmenta l Medi a6-2 0 6.4. 1 Soil s 6-2 0 6.4. 2 Wate r

6-2 1 6.4. 3 Plant s 6-2 3 6. 5 Reference s fo r

Chapte r 6 6-2 5 7 . ENVIRONMENTA LCONCENTRATION S AN D POTENTIA L EXPOSURE S 7- 1 7. 1 Ambien t

Ai r Exposure s 7- 1 7.1. 1 Nationa l Ai r

Surveillanc e Networ k

(NASN ) Dat a7- 1 7.1. 2 Airborn e Particl e Siz e Distributio n7- 4 7.1. 3 Vertica l Gradient s o f Lea dinth e Atmospher e 7- 4 7. 2 Mobil e Sourc e Exposure s 7- 6 7. 3 Poin t

Sourc e Exposure s 7- 7 7. 4 Dietar y Exposure s 7- 9 7.4. 1 Foo d7- 9 7.4. 2 Wate r

7-1 1 7. 5 Occupationa l Exposure s 7-1 2 7.5. 1 Exposure s in Lea dMining , Smelting , an dRefinin g ... . 7-1 2 7.5. 2 Exposure s in Weldin g an dShipbreakin g 7-1 3 7.5. 3 Exposure s in th e Electri c Storag e Batter y Industr y ... . 7-1 3 7.5. 4 Exposure s in th e Printin g Industr y 7-1 3 7.5. 5 Exposure s in Alky l Lea dManufactur e 7-1 3 7.5. 6 Exposure s in Othe r Occupation s 7-1 3 7.5. 7 Exposure s Resultin g fro mManmad e Material s 7-1 4 7.5. 8 Historica l Change s 7-1 4 7. 6 Reference s fo r

Chapte r 7 7-1 4 xi iP.1 5

Page 8 . EFFECT S O FLEA D O N ECOSYSTEM S 8- 1 8. 1 Effect s o n Domesti c Animals , Wildlife , an dAquati c Organism s 8- 1 8.1. 1 Domesti c Animal s 8- 1 8.1. 2 Wildlif

e 8- 3 8.1. 3 Aquati c Organism s 8- 5 8. 2 Effect s o n Plant s 8- 8 8.2. 1 Route s o f

Plan t Exposur e 8- 8 8.2. 2 Effect s o n Vascula r Plant s 8-1 0 8.2. 3 Effect s o n Nonvascula r Plant s 8-1 1 8. 3 Effect s o n Relationship s Betwee n Arthropod s an dLitte r Decom positio n 8-1 3 8. 4 Reference s fo r

Chapte r 8 8-1 3 9 . QUANTITATIV EEVALUATIO N O FLEA D AN D BIOCHEMI CA LINDICE S O FLEA D EXPOSUR EI N PHYSIOLOGICA L MEDI A 9- 1 9. 1 Genera l Samplin g Procedure s fo r Lea din Biologica l Media . . . 9- 1 9. 2 Bloo dLea d9- 2 9. 3 Urin e Lea d9- 3 9. 4 Soft-Tissu e Lea d9- 3 9. 5 Hai r Lea d9- 3 9. 6 Lea din Teet han dBon e 9- 3 9. 7 Comparativ e Studie s o f Method s fo r

Measuremen t

o f Lea din Biologica l Medi a9- 4 9. 8 Measurement s o f

Urinar y 8-Aminolevulini c Aci d(ALA-U ) .. . 9- 4 9. 9 Measurement s o f

8-Aminolevulini c Aci dDehydratas e (ALAD ) 9- 5 9.1 0 Measurement s o f

Fre e Erythrocyt e Protoporphyri n (FEP)... . 9. 6 9.1 1 Reference s fo r

Chapte r 9 • 9- 6 10 . METABOLIS M O FLEA D 10- 1 10. 1 Introductio n 10- 1 10. 2 Absorptio n 10- 1 10.2. 1 Respirator y Absorptio n 10- 1 10.2. 2 Gastrointestina l Absorptio n10- 2 10.2. 3 Cutaneou s Absorptio n 10- 5 10. 3 Distributio n 10- 5 10.3. 1 Huma n Studie s 10- 5 10.3. 2 Anima l Studie s 10- 6 10. 4 Eliminatio n 10- 7 10.4. 1 Huma n Studie s 10- 7 10.4. 2 Anima l Studie s 10- 7 10. 5 Alky l Lea dMetabolis m10- 8 10. 6 Metaboli c Consideration s inth e Identificatio n o f Susceptibl e Subgroup s in th e Populatio n10- 8 10. 7 Reference s fo r

Chapte r 1 0 10- 9 11 . BIOLOGICA LEFFECT S O FLEA D EXPOSUR E11- 1 11. 1 Introductio n 11- 1 11. 2 Cellula r

an dSubcellula r

Effect s o f

Lea d11- 1 11.2. 1 Effect s o nEnzyme s , 11- 1 11.2. 2 Organella r

an dCellula r

Effect s 11- 1 11.2. 3 Effect s o f

Lea do n Chromosome s 11- 4 11.2. 4 Carcinogenesi s 11- 5 11. 3 Clinica l Lea dPoisonin g 11- 6 11. 4 Hematologica l Effect s o f Lea d11- 7 xii i1P P I (• • P.1 6

Page 11.4. 1 Anemi a11- 7 11.4. 2 Effect s o f

Lea do nErythrocyt e Morpholog y an dSurviva l 11- 7 11.4. 3 Effect s o f

Lea do nHem e Synthesi s 11-8 11.4. 4 Othe r

Hematologica l Effect s 11-1 3 11.4. 5 Summar y o f

Effect s o f

Lea do n th e Hematopoieti c Syste m11-1 3 11. 5 Effect s o f

Lea do n Neurophysiolog y an dBehavio r 11-1 4 11.5. 1 Huma n Studie s 11-1 5 11.5. 2 Anima l Studie s 1 1 -2 6 11. 6 Effect s o f

Lea do n th e Rena l Syste m1 1 -4 4 11.6. 1 Acut e Effect s 1 1 -4 4 11.6. 2 Chroni c Effect s 1 1 -4 4 11. 7 Reproductio n an dDevelopmen t 1 1 -4 5 11.7. 1 Huma n Studie s 1 1 ^4 6 11.7. 2 Anima l Studie s 1 1 -4 8 11. 8 Th e Endocrin e Syste m11-5 1 11. 9 Th e Hepati c Syste m11-5 2 11. 1 OTh e Cardiovascula r Syste m11-5 2 11.1 1 Th e Immunologi c Syste m11-5 3 11.1 2 Th e Gastrointestina l Syste m1 1 -5 4 11.1 3 Reference s fo r

Chapte r 1 1 11-5 4 12 . ASSESSMEN T O FLEA D EXPOSURE S AN D ABSORPTIO N I N HUMA N POPULATION S 12- 1 12. 1 Introductio n 12- 1 12. 2 Lea din Huma n Population s 12- 1 12.2. 1 Statistica l Description s an dImplication s 12- 1 12.2. 2 Geographi c Variabilit y in Huma n Bloo dLea dLevel s . 12- 4 12.2. 3 Demographi c Variable s an dHuma nBloo dLea dLevel s 12- 6 12. 3 Relationship s Betwee n Externa l Exposure s an dBloo dLea d Level s 12-1 0 12.3. 1 Ai r

Exposure s 12-1 0 12.3. 2 Soi l an dDas t

Exposure s 12-2 9 12.3. 3 Foo dan dWate r Exposure s 12-3 2 12.3. 4 Effect s o f

Lea din th e Housin g Environment : Lea din Pain t 12-3 3 12.3. 5 Secondar y Exposur e o f Childre n Fro mParents ' Occupa tiona l Exposur e 12-3 6 12.3. 6 Miscellaneou s Source s o f Lea d12-3 8 12. 4 Summar y 12-3 8 12. 5 Reference s fo r

Chapte r 1 2 12-3 9 13 . EVALUATIO N O FHUMA N HEALT H RISK S FRO M EXPOSUR E T O LEA D AN D IT S COMPOUND S 13- 1 13. 1 Introductio n 13- 1 13. 2 Sources , Routes , ari dMechanism s o f Entr y 13- 1 13.2. 1 Source s 13- 1 13.2. 2 Route s an dMechanism s o f Entr y 13- 2 13. 3 Evidenc e o f

Increase dBloo dLea dLevel s inHuman s Expose dt o Environmenta l Lea d13- 2 13.3. 1 Relationship s Betwee nBloo dLea dLevel s an dSingle Sourc e Exposure s 13- 2 13.3. 2 Multiple-S®urc e Exposure s 13- 3 xi vP.1 7

Page 13.3. 3 Effec t

o f Hos t Factor s o n Bloo dLea dLevel s 13- 3 13.3. 4 Summar y o f

th e Quantitativ e Relationshi p 13- 3 13. 4 Averaging-Tim e Consideration s 13- 4 13. 5 Biologica l an dAdvers e Healt hEffect s o f Lea din Ma n 13- 4 13.5. 1 Assessmen t

o f Hematologica l Effect s o f Lea d13- 4 13.5. 2 Assessmen t

o f Neurobehaviora l Effect s o f Lea d13- 6 13.5. 3 Effect s o f

Lea do nReproductio n an dDevelopment... . 13- 7 13.5. 4 Othe r

Healt hEffect s 13- 8 13.5. 5 Dos e Effect/Respons e Relationship s 13- 8 13. 6 Population s a t

Ris k 13-1 1 13.6. 1 Childre na s aPopulatio n a t Ris k 13-1 1 13.6. 2 Pregnan t

Wome nan dth e Conceptu s a s aPopulatio n a t Ris k , 13-1 2 13. 7 Descriptio n o f

Unite dState s Populatio n in Relatio n t o Probabl e Lea dExposure s 13-1 3 13. 8 Reference s fo r

Chapte r 1 3 13-1 4 APPENDICE S A . GLOSSAR Y A- l B . PHYSICAL/CHEMICA LDAT A FO RLEA D COMPOUND S B- l C . ADDITIONA LSTUDIE S O FENVIRONMENTA LCONCENTRA TION S O FLEA D C- l D . UNIT S AN D METRI C CONVERSIO NFACTOR S D- l E . A REVIE WO FTHRE ESTUDIE S O N TH EEFFECT S O FLEA D SMELTE REMISSION S I N E LPASO , TEXA S E- l

xvT"* -



## FIGURE S Page 4- 1 Sequenc e o f

operation s involve dinmonitorin g fo r lea din th e en vironmen t

4- 2 5- 1 Approximat e flo w o f lea dthroug hU.S . industr y i n197 5 5- 1 5- 2 Locatio n o f

majo r lea doperation s inth e Unite dStates , 197 6 5- 3 6- 1 Simplifie decologi c flo w char t fo r lea dshowin g principa l cyclin g pathway s an dcompartment s 6- 1 6- 2 Effec t

o f variou s drivin g condition s o nth e amoun t o f lea dexhauste d6- 2 6- 3 Effec t

o f spee do n siz e distributio no f exhaus t particle s at

differen t roa dloa dcruis e condition s an dusin g Indolen e H O O fue l 6- 2 6- 4 Cumulativ e mas s distribution s fo r lea daeroso l i naut o exhaus t an da t Pasadena , arecepto r

samplin g sit e 6- 3 6- 5 Differentia l mas s distribution s fo r lea d1 mfro mafreewa y an dat Pasaden asamplin g site s 6- 3 6- 6 Cumulativ e mas s distributio n o f lea dparticle s b y siz e 6- 4 6- 7 Air-lea dvalue s a s afunctio no f traffi c volum e an ddistanc e fro mth e highwa y 6- 9 6- 8 Relationshi p o f

th e diamete r

o f th e particle s (mass ) t o distanc e fro m th e highwa y 6- 9 6- 9 Lea dconcentratio n profile s inth e ocean s 6- 9 6-1 0 Midpoin t

collectio n locatio n fo r

atmospheri c sample s collecte dfro m R . V . Trident

nort ho f 30°N , 197 0 throug h197 2 6-1 0 6-1 1 Th e EF crus t

value s fo r

atmospheri c trac e metal s collecte din th e Nort hAtlanti c westerlie s an dat th e Sout hPol e 6-1 0 6-1 2 Lea dconcentratio n profil e i nsno w strat ao f norther n Greenlan d. . 6-1 1 6-1 3 Worl dlea dsmelte r an dalky l lea dproductio nsinc e 175 0 A.D . . . . 6-1 1 6-1 4 210 P b i n Storbree n glacie r ice , 1954-196 6 6-1 1 6-1 5 Predicte ddepositio n velocit y at indicate dheigh t

fo r fi» = 2 0 cm/se c an dz 0 = 3. 0 c m6-1 4 6-1 6 Predicte ddepositio n velocitie s a t 1- mheigh t fo r z 0 = 3. 0 c m... . 6-1 4 6-1 7 Predicte ddepositio n velocitie s a t 1 mfo r / x « = 20 0 cm/se c 6-1 4 6-1 8 Regressio n o f

percentag e lea dparticulate s remove db y dr y deposi tio n wit hdistanc e fro mroadwa y 6-1 5 6-1 9 Compariso n o f

siz e distributio no f

lea dparticulate s collecte da t 2 0 an d64 0 f

t fro ma n expresswa y nort ho f Cincinnati , Ohi o 6-1 5 6-2 0 Atmospheri c concentration s o f lea dan dcarbo n monoxid e a s afunc tio n o f lo g o f distanc e fro medg e o f

highwa y 6-1 5 6-2 1 Atmospheri c lea dconcentratio na t freewa y sit e inPal o Alto , Califor nia , o n Augus t

15 , 196 6 6-1 6 6-2 2 Averag e lea di n dr y fallou t a s afunctio n o f

distanc e fro mth e freewa y 6-1 6 6-2 3 Fat e o f

lea dcontribute dfro mautomotiv e traffi c in Lo s Angele s Basi n 6-1 7 xv iP.1 9

NumberPage 6-2 4 Contaminatio n o f dus t b y lea demission s fro mtw o secondar y smelter s 6-1 7 6-2 5 Tota l depositio n o f lea do n Teflo nplate s a t variou s height s abov e th e roo f o f Kec k Laboratories , Californi aInstitut e o f Technology , Pasaden a6-1 9 6-2 6 Lea ddistributio n betwee nfiltrat e an dsuspende dsolid s in strea m

wate r fro murba n an drura l compartment s 6-2 2 7- 1 Seasona l pattern s an dtrend s in quarterl y averag e urba n lea dcon centration s 7- 3 7- 2 Nationwid e trend s in regular , premium , an dunleade dgasolin e sales ,

1960-197 6 7- 4 7- 3 Nationwid e trend s in lea dconten t o f regula r an dpremiu mgasoline , 1960-197 6 7- 4 7- 4 Annua l ambien t ai r lea dconcentratio n nea r asmelter , b y area , befor e th e Augus t

197 4 an dAugus t

197 5 survey s 7- 8 8- 1 Simplifie decologi c flo w char t fo r lea dshowin g principa l cyclin g pathway s an dcompartment s 8- 1 8- 2 Concentratio n o f lea din thre e specie s o f smal l mammal s trappe d besid e majo r

an dmino r

road s an dat

arabl e an dwoodlan dsite s 8- 5 8- 3 Mea n lea dconten t in groupe dinsec t

sample s take n fro mlo w an d hig hlea demissio n area s fo r sucking , chewing , an dpredator y feed in g type s 8- 7 8- 4 Mea n lea dlevel s i n representativ e organism s an dsediment s o f th e compartment s o f

th e drainag e basi n o f

th e Salin e Branc ho f

th e Vermilio n River , Illinoi s 8- 7 8- 5 Tre e rin g analysi s o f lea dconcentration s inurba nan drura l tree s . 8- 9 11- 1 Lea deffect s o n hem e biosynthesi s 11- 8 11- 2 McCarth y genera l cognitiv e inde x score s a s afunctio n o f degre e o f lea dexposur e 11-2 1 11- 3 Score s o n McCarth y subscale s a s afunctio no f degre e o f

lea dex posur e 11-2 1 11- 4 Peronea l nerv e conductio n velocit y versu s bloo dlea dlevel , Idaho ,

197 4 11-2 5 12- 1 Estimate dcumulativ e distributio n o f bloo dlea dlevel s for

popula tion s in whic hth e geometri c mea n leve l i s 15 , 25 , o r 4 0 /xg/dl. . 12- 2 12- 2 Estimate dcumulativ e distributio no f bloo dlea dlevel s fo r

popula tion s havin g ageometri c mea n bloo dlea dleve l o f 2 5 /xg/dl , bu t geometri c standar ddeviation s o f 1.2 , 1.3 , o r

1. 5 12- 2 12- 3 Geometri c mean s fo r bloo dlea dvalue s b y rac e an dage , Ne w Yor k City , 197 1 12- 9 12- 4 Arithmeti c mea n o f ai r lea dlevel s b y traffi c count , Dallas , 1976. . 12-1 2 12- 5 Bloo dlead.concentratio n an dtraffi c densit y b y se x an dage , Dallas ,

197 6 12-1 2 12- 6 Monthl y ambien t ai r lea dconcentration s inKellog , Idaho , 197 1 throug h197 5 12-1 6 12- 7 Annua l ambien t

ai r lea dconcentration , b y area , befor e th e Augus t 197 4 an dAugus t

197 5 survey s 12-1 6 12-8 Bloo dlea dversu s ai r lea dfo r urba n mal e worker s 12-2 5 12- 9 Cumulativ e distributio no f lea dlevel s in dwellin g unit s 12-3 4 12-1 0 Cumulativ e distributio n o f lea dlevel s b y locatio n in dwelling , al l age s 12-3 5 12-1 1 Cumulativ e distributio no f lea dlevel s indwellin g unit s withunsoun d pain t condition s 12-3 5 xvi iP.2 0



### 12-1 2 Cumulativ e frequenc y distributio n of bloo dleadlevel s foundi n Pittsburg hhousin g survey 12-3 6 12-1 3 Correlatio n o

f children' s bloo dleadlevel s wit hfraction s o

f surface s withi n adwellin g havin g leadconcentration s > 2 m g Pb/cm 2 

### 12-3 6 13- 1 Dose-respons e curv e fo r percen t ALA D inhibitio n fo

r adult s an d childre n a s afunctio n of

bloo dleadleve l 13- 9 13- 2 Dose-respons e curv e fo r ALA i n urin e (ALA-U ) a s afunctio n o f bloo dlea dlevel 13- 9 13- 3 Dose-respons e curv e fo r FE Pa s afunctio n o

f bloo dleadlevel... . 13- 9 13-4 Dose-respons e curv e fo r FE Pa s afunctio n o

f bloo dlea

dlevel... . 13- 9 13- 5 Dose-respons e curv e for FE Pa s afunctio n of

bloo dleadlevel... . 13-1 0 13- 6 EPA calculate ddose-respons e curv e for ALA- U (fromAza

r e t al. ) 13-1 0 C- l Location s o

f fixedsamplin g station s i n Kanawh aRiver

Valley... . C- 3 C- 2 Air samplin g site s fo

r Souther n Solano , California , study C- 3 C- 3 Omaha , Nebraska , study : mea n monthl y composite atmospheri c lead at industrial , commercial , mixed , an dtw o residential site s C- 4 C- 4 Settleabl e particulat e lea dradia l distributio n fro

mHelen aValle y environmental pollutio n study C- 5 C- 5 Annual averag e o

f settleabl e particulat e leada t site s nea r Missour i leadmin e an dsmelter

C- 6 C- 6 Schemati c pla

n o f lea dmin e andsmelter

fromMez aValley , Yugoslavia , stud

y C- 7 C- 7 Soil transect s b

y tw o streets : Curv e A = low traffi c volum e (40 0 veh/day) ; Curv e B = hig

htraffi c volum e (14,00 0 veh/day ) C- 8 C- 8 Surfac e soi l level s o f lea di n E l Paso , Texas , an dDon aAn aCounty , Ne w Mexico , 197 2 C- 8

xvi nP.2 1



# TABLE S

Page 1- 1 Bloo dlea dlevel s versu s lowest-observed-effect s level s 1-1 3 1- 2 Estimate dpercentag e o f subject s wit hALA- U exceedin g 5 mg/ 1 fo r variou s bloo dlea dlevel s 1-1 4 1- 3 Estimate dpercentag e o f childre nwit hE Pexceedin g specifie dcutof f point s fo r

variou s bloo dlea dlevel s 1-1 4 3- 1 Propertie s o f

elementa l lea d3- 1 3- 2 Isotope s o f

lea d3- 1 3- 3 Propertie s o f

majo r organolea dcompound s 3- 2 4- 1 Dail y foo dintak e 4- 6 5- 1 U.S . consumptio n o f lea db y produc t

categor y 5- 2 5- 2 Estimate datmospheri c lea demission s fo r th e Unite dStates , 197 5 . 5- 3 6- 1 Compariso n o f

siz e distribution s o f

lead-containin g particle s in ma jo r samplin g are a6- 4 6- 2 Result s o f

atmospheri c samplin g fo r organi c an dparticulat e lead . . 6- 5 6- 3 Percentag e o f

particulat e versu s vapor-phas e lea din urba n ai r sam ple s 6- 5 6- 4 Analyse s o f

fiv e replicat e sample s take nina n undergroun dparkin g garag e 6- 5 6- 5 Averag e compositio n o f particulat e lea dcompound s emitte din aut o exhaus t 7 6- 6 6- 6 Effect s o f

agin g o n lea dcompound s i nsample s o f aut o exhaus t

a s determine db y electro n microprob e 6- 6 6- 7 Concentratio n rang e an dmea nEF crus t value s fo r

atmospheri c trac e metal s collecte dove r

th e Atlanti c nort ho f

30 ° N 6-1 0 6- 8 Lea daeroso l productio nin th e norther n hemispher e compare dwit h

lea dconcentration s inCam p Century , Greenland , sno w a t differen t time s 6-1 1 6- 9 Termina l velocitie s o f spherica l particle s o f

uni t densit y a t

groun d leve l 6-1 2 6-1 0 Summar y o f

fiel ddat afro mPal o Alto , Californi a6-1 7 6-1 1 Depositio n o f

lea da t th e Walke r

Branc hWatershed , 197 4 ...... . 6-1 7 6-1 2 Lea dcompound s identifie din roadsid e soil s b y X-ra y powde r

diffractio n technique s 6-2 1 7- 1 Numbe r

o f NAS N urba nstation s whos e dat afal l withi n selecte dan nua l averag e lea dconcentratio nintervals , 1966-197 4 7- 2 7- 2 Numbe r

o f NAS N nonurba nstation s whos e dat afal l withi n selecte d annua l averag e lea dconcentratio nintervals , 1966-197 4 7- 2 7- 3 Cumulativ e frequenc y distribution s o f quarterl y lea dmeasurement s a t urba n station s b y year , 197 0 throug h197 4 7- 2 7- 4 Cumulativ e frequenc y distribution s o f quarterl y lea dmeasurement s at nonurba n station s b y year , 197 0 throug h197 4 7- 2 7- 5 NAS N station s withannua l averag e lea dconcentration s > 3. 0 /xg/m 3 7- 3 xi xP.2 2

NumberPage 7- 6 Quarterl y an dannua l siz e distribution s o f lead-bearin g particle s fo r si x cities , 197 0 7- 5 7- 7 Lea din ai r

o n Mai n Street , Brattleboro , Vermont , Septembe r 1 2 an d 13 , 197 2 7- 5 7- 8 Airborn e lea dconcentration s a t 5 - an d20-f

t elevation s abov e stree t leve l 7- 6 7- 9 Monthl y averag e lea dconcentration s fo r 197 5 Lo s Angele s catalys t stud y 7- 6 7-1 0 Lea ddus t

o n an dnea r

heavil y travele droadway s 7- 7 7-1 1 Lea dconten t

in o r o n roadsid e soi l an dgras s a s afunctio n o f distanc e fro mtraffi c an dgras s dept hinprofil e 7- 7 7-1 2 Lea ddus t

in residentia l area s 7- 8 8- 1 Accumulatio n o f certai n heav y metal s fro mseawate r b y fis h(Ammodytes an dClupea) an dapuffi n 8- 3 8- 2 Summar y o f

lea dconcentration s inbir dorgan s an dtissue s fro marea s o f high-lea dan dlow-lea denvironment s 8- 4 8- 3 Mea n lea dconcentration s in organ s an dtissue s o f smal l mammal s fro mindicate darea s o f environmenta l lea dexposure s 8- 6 8- 4 Lea dconcentration s o f insect s a t

tw o distance s fro mahigh-traffic volum e roa d(interstat e highway ) 8- 6 8- 5 Lea dconcentration s o f predominan t

organism s fro mth e rural , ur ban , an dcombine dcompartment s o f th e drainag e basi n o f th e Salin e Branc ho f

th e Vermilio nRiver , 11 1 8- 8 8- 6 Summar y o f

goldfis htoxicit y dat a8- 8 8- 7 Concentration s o f selecte dheav y metal s infres hwate r an din fresh wate r alga l bloom s 8-1 2 10- 1 Lea dconten t

o f fresh , processed , an dcanne dfoodstuffs 10- 3 10- 2 Effec t

o f differen t diet s o nlea dabsorptio nexpresse da s th e rati o o f mea n retentio n fo r

experimenta l an dcontro l subject s 10- 4 10- 3 Percen t

absorptio n o f

differen t lea dcompound s relativ e t o lea dace tat e 10- 4 11- 1 Enzyme s affecte db y lea dinanima l studie s 11- 2 1 1 - 2 Enzyme s affecte db y lea dinhuma nstudie s 11- 2 1 1 - 3 Compariso n o f

tes t result s in lea dan dcontro l group s 1 1 -2 2 11- 4 Summar y o f

result s o f

huma n studie s o n neurobehaviora l effect s a t "moderate " bloo dlea dlevel s 1 1 -2 7 1 1 - 5 Effect s o f

lea dexposur e o n locomoto r activit y inlaborator y animal s 1 1 -3 0 11- 6 Lea dexposur e an dresultin g bloo dlea dlevel s in experiment s measurin g locomoto r

activit y in rat s 1 1 -3 2 1 1 - 7 Protocol s use dfo r th e stud y o f

anima l learnin g 1 1 -3 5 1 1 - 8 Stag e o f

learnin g 1.1-3 7 11- 9 In vivo effect s o f

lea dexposur e o nneurochemistr y 1 1 -3 9 11-1 0 Statistic s o n th e effec t o f lea do n pregnanc y 11-4 6 11-1 1 Reproductiv e performanc e o f F , lead-toxi c rat s 1 1 -4 9 12- 1 Analysi s o f

varianc e fo r

th e logarithm s o f

bloo dlea dvalue s fo r selecte dstudie s 12- 3 12- 2 Bloo dlea dlevel s o f remot e population s 12- 4 12- 3 Ag e an dsmoking-adjuste dgeometri c mea nbloo dlead s in urba n ver su s suburba n area s o f

thre e citie s : 12- 5 12- 4 Bloo dlea dconcentration s insi x urba n an don e rura l population. . 12- 5 12- 5 Mea n bloo dlea dvalue s fo r childre nin1 4 intermediate-size dcitie s in Illinois , 197 1 12- 6 x xNumberft*' 12- 6 Bloo dlea dlevel s (whol e blood ) inchildre n in U.S . smelte r an dcom pariso n towns , 197 5 12- 7 12- 7 Geometri c mea n an dgeometri c standar ddeviation s (i n parentheses ) o f bloo dlea dlevel s b y ag e an dstud y secto r 12- 7 12- 8 Proportio n o f

childre n withbloo dlea dvalue s betwee n 5 0 an d9 9 Mg/dl , b y age , Chicago , 1971-197 5 12- 7 12- 9 Mea n bloo dlea db y age , sex , an dG6P D statu s in 155 9 urba n blac k childre n 12- 8 12-1 0 Geometri c mea n blood-lea dlevel s in Ne w Yor k Cit y lea dscreenin g progra m12- 8 12-1 1 Numbe r

o f children' s initia l screen s in Ne w Yor k Cit y program s b y race/ethnicit y an dyear , 1970-197 7 12- 9 12-1 2 Bloo dlea dlevel s in militar y recruits , b y rac e an dplac e 12- 9 12-1 3 Geometri c mea n bloo dlea dlevel s inNe w Yor k lea dscreenin g pro gram , 1970-1976 , fo r

childre n u p t o 7 2 month s o f age , b y rac e an d yea r 12-1 0 12-1 4 Mea n bloo dlea dlevel s fo r stud y an dcontro l groups , Houston... . 12-1 1 12-1 5 Arithmeti c an dgeometri c mea n bloo dlea dlevel s fo r Lo s Angele s an dLancaster , California , b y se x an dag e 12-1 1 12-1 6 Mea n ai r

lea dlevel s indoor s an doutdoor s at tw o traffi c densities , Dallas , Texas , 197 6 12-1 2 12-1 7 Soi l lea dlevel s b y traffi c densit y 12-1 2 12-1 8 Bloo dlea dconcentration s in relatio n t o soi l lea dconcentration s an d traffi c densit y 12-1 3 12-1 9 Bloo dlea dlevel s in childre n age d1 t o 5 in Newark , Ne w Jersey , in relatio n t o distanc e o f

residenc e fro mamajo r roadway , 197 1 . . 12-1 3 12-2 0 Geometri c mea n bloo dlea dlevel s b y are acompare dwit hestimate d ai r lea dlevel s fo r

1 - t o 9-year-ol dchildre nlivin g nea r Idah o smelte r 12-1 5 12-2 1 Mea n bloo dlea dlevel s in childre n livin g in vicinit y o f aprimar y lea dsmelter , 197 4 an d197 5 12-1 7 12-2 2 Mea n bloo dlea dlevel s inselecte dYugoslavia npopulations , b y esti mate dweekly , time-weighted , ai r lea dexposur e 12-1 8 12-2 3 Lea dconcentration s inair , dustfall , an dblood , Omaha , Nebraska , study , 1970-197 7 12-1 9 12-2 4 Geometri c mea n ai r an dbloo dlea dlevel s fo r fiv e city-occupatio n group s 12-2 1 12-2 5 Geometri c mea n ai r an dbloo dlea dvalue s fo r 1 1 stud y population s 12-2 2 12-2 6 Mea n ai r

an dbloo dlea dvalue s fo r fiv e zone s inToky o stud y ... . 12-2 2 12-2 7 Lengt ho f

tim e neede dfo r

mea nbloo dlea dvalue s t o reac hspecifie d level s a t tw o exposur e level s 12-2 3 12-2 8 Estimate dbloo dlea dt o ai r lea dratio s fo r

fou r ai r lea dconcentra tion s 12-2 5 12-2 9 Yearl y mea n ai r

an dbloo dlea dlevel s o f blac k female s in relatio n t o distanc e o f

residenc e fro mabus y highwa y :.. . . 12-2 6 12-3 0 Bloo dan dai r

lea dlevel s b y se x in Finnis hpopulatio n stud y 12-2 7 12-3 1 Bloo dan dai r

lea ddat afro mclinica l stud y 12-2 8 12-3 2 Estimate dpercentag e o f populatio nexceedin g aspecifi c bloo dlea d leve l in relatio n t o ambien t ai r lea dexposur e 12-2 8 12-3 3 Compariso n o f

bloo dlea dlevel s inchildre nwit hai r lea dlevel s fo r 197 4 an d197 5 12-2 9 12-3 4 Mea n bloo dan dsoi l lea dconcentration s in Englis hstud y 12-3 0 12-3 5 Summar y o f

soi l lead/bloo dlea drelationship s 12-3 2

xx iP.2 4

NumberPage 

### 12-3 6 Bloo dleadlevel s o f 77 1 person s i

n relatio n t o leadconten t

o f drink in g water , Boston , Massachusett s 12-3 3 12-3 7 Result s o

f screenin g andhousin g inspectio n i n childhoo dlead poisonin g contro l projec t

b y fisca l yea r 12-3 6 12-3 8 Geometri c mea

n bloo dlea

dlevel s o f childre n b

y parenta l employ ment 12-3 7 12-3 9 Geometri c mea

n bloo dlea

dlevel s fo r childre n base don reporte doc cupatio n o

f father , histor

y o f pica , an ddistanc e o

f residenc e fro

m smelter 12-3 7 13- 1 Source s o

f leadfo r huma n exposure s 13- 2 13- 2 Summar

y o f lowes t observe deffec

t level s 13- 8 13- 3 Percentag e o

f subject s wit

hALA- U exceedin g 5 mg/ 1 fo r variou s bloo dleadlevel s 13-1 0 13-4 Estimate dpercentage s o f childre n wit

hEPexceedin g cut-of

f point s fo r variou s bloo dlea

dlevel s 13-1 1 13- 5 Populatio n andpercent distribution , urban an drural , b y race, 197 0 censu s 13-1 3 13- 6 Number

o f birth s b y rac e an dsiz e o

f populatio n 13-1 4 B- l Physica

l propertie s o

f inorgani c leadcompound s B- l B- 2 Temperatur e variatio n o f th e vapo r

pressure s o

f commo n leadcom pound s B- 2 C- 1 Summar

y o f monthl y averag e lea

dconcentration s foundi

n seven-cit

y study C- 2 C- 2 Seasona

l lea dconcentration s i

n Birmingham , Alabama , area , 1964-196 5 C- 2 C- 3 Leaddat afro

mKanawh aValle y Stud

y C- 3 C-4 Dat aon lea

ddepositio n i

n 7 7 midwester

n citie s C- 3 C- 5 Leadconcentration s i n air determine db

y analysi s o

f suspende dpar ticulate , Souther

n Solan o County , California , March-May 1970 . C- 4 C- 6 Tota l leadan dlea dfallou t determine db

y analysi s o

f dustfal l sam ples , Souther

n Solan o County , California , June-September 197 0 C- 4 C- 7 Leadconcentration s i n suspende dparticulat e ai r sample s fro

mEl Paso , Texas , 197 1 C- 5 C- 8 Particulat e dat asummar y fro mHelen aValley , Montana, environ mental pollutio n study C- 5 C- 9 Pea

k depositio n rate s o

f leadmeasure di

n Southeas t

Missour i C- 6 C-1 0 Atmospheri c leadconcentration s (24-hr ) i n th e Mez aValley , Yugoslavia , November

197 1 t o Augus t

197 2 C- 7 C-1 1 Compariso n of

leadlevel s i

n th e surrounding s o

f tw o leadindustry facilitie s an da

n urba n contro l are aC- 7 C-1 2 Leadconten t

o f soil nea r 3-year-ol dRussia

n smelter , E . Kazakhstan C- 8 C-1 3 Leadconten t

o f soi l i n vicinit y o f Russia n leadplan t

i n Kazakhsta

n C- 9

xx n

## ABBREVIATION S AN D SYMBOL S

A AA S AL A ALA D ALA S ALA- U 8-AL A APH A AST M AS V b.p . B.W . °C C a C d CD C (Ch 3 ) 4 P b (CH 3 ) 6 Pb 2 (C 2 H 5 ) 4 P b (C 6 H 5 ) 4 P b (C 2 H 5 ) 6 Pb 2 c m CN S 

### co 3 

### = C P CP G CP- U C u D A d l DN A EDT A E P EP A

° F Angstro m(10 1 0 meter )

Atomi c absorptio n spectroscop y Delta-aminolevulini c aci d Delta-aminolevulini c aci d dehydratas e Delta-aminolevulini c aci d synthetas e Delta-aminolevulini c aci di n urin e Delta-aminolevulini c aci d America n Publi c Healt h Associatio n America n Societ y fo r

Testin g an d Material s Anodi c strippin g voltammetr y Boilin g poin t Bod y weigh t Degree s Celsiu s (centigrade ) Calciu m Cadmiu m Cente r fo r Diseas e Contro l (Atlanta , Ga. ) Tetramethy l lea d(als o TM Lo r Me 4 Pb ) Hexamethy l lea d Tetraethy l lea d(als o TE Lo r Et 4 Pb ) Tetrapheny l lea d Hexaethy l lea d Centimete r Centra l nervou s syste m Carbonat e io n Coproporphyri n Coproporphyrinoge n Coproporphyri n in urin e Coppe r Dopamin e Decilite r Deoxyribonuclei c aci d Ethylenediaminetetraacetat e Erythrocyt e protoporphyrin ; als o erythrocyt e porphyri n U.S . Environmenta l Protectio n Agenc y Degree s Fahrenhei t FD A 59 F e Fe 2 0 3 FE P f t g GS H G-6-PD H h a 5-HIA A h r IAR C ICR P in i.p . K kca l RC R kg k m 1 LC , LC 5 0 m M ma x Me 3 PbA c (Me 3 Pb) 2 S Me V MEPP s m g M g mi n MME D ml m o m.p . Foo dan dDru g Administratio n

Radioisotop e o f

iro n Ferri c oxid e Fre e erthythrocyt e protoporphyrin ; als o fre e erythrocyt e porphyri n Foo t Gra m Glutathion e (reduced ) Glucose-6-phosphat e dehydrogenas e Hectar e 5-Hydroxyindol e aceti c aci d Hou r Internationa l Agenc y fo r Researc h o n Cance r Internationa l Radiologica l Protectio n Commissio n Inc h Intraperitonea l Potassiu m Kilocalori e Respirator y contro l rat e Kilogra m Kilomete r Lite r Concentratio nletha l t o 1 percen t o f recipient s Concentratio n letha l t o 5 0 percen t o f recipient s Mete r Mola r Maximu m Trimethy l lea dacetat e Trimethy l lea dsulfid e Meg aelectronvolt s (10 6 electronvolts ) Miniatur e end-plat e potential s Milligra m Magnesiu m Minut e Mas s media n equivalen t diamete r Millilite r Mont h Meltin g poin t XXll lP.2 6

M T N a NAD H NA S NAS N N E n g N i n m NO" 3 NS F NV S P P b 204p b Pb + + Pb- A Pb- B PbBr 2 PbBrC l Metri c to n

Sodiu m Reduced(hydrogenated ) nicotinamid e adenin e dinucleotid e Nationa l Academ y o f

Science s Nationa l Ai r

Surveillanc e Network s Norepinephrin e Nanogra m Nicke l Nanomete r Nitrat e io n Nationa l Scienc e Foundatio n Nonvolatil e solid s Phosphoru s Lea d Isotop e o f

Lea d( 2l0 Pb , etc. ) Diavalen t

lea dio n Concentratio n o f

lea din ai r Concentratio n o f

lea din bloo d Lea dbromid e Lea d(II ) bromochlorid e PbBrCl-NH 4 C I Lea dbromochloride-ammoniu m [Pb(C 2 H 3 0 2 ) 2 - 2Pb(OH) 2 ] PbCl 2 PbC0 3 

### PbCr6 4 PbF 2 Pb(N0 3 ) 2 Pb O PbO x (PbO) 2 Pb 3 0 4 Pb(OCOCH 3 ) 2 Pb(OH) 2 Pb(OH)B r Pb(OH)C l Pb(OH) 2 C0 3 PbO.PbS0 4 Pb 4 0(P0 4 ) 2 chlorid e

Basi c lea d(II ) acetat e Lea dchlorid e Lea dcarbonat e Lea dchromat e Lea dfluorid e Lea dnitrat e Lea doxid e Lea doxide s Lea doxid e dime r Lea d(IV ) oxid e Lea d(II ) acetat e Lea dhydroxid e Lea d(II ) hydroxybromid e Lea dhydroxychlorid e Basi c lea dcarbonat e Basi c lea dsulfat e Lea doxyphosphat e Pb(P0 3 ) 2 Pb 3 (P0 4 ) 2 Pb s (P0 4 ) 3 O H Pb S PbS0 4 PB G pC i PIX E P H PO ? P P pp b pp m PV C RB C RN A s.c . sc m se c SGO T SGP T S H S0 2 SO ? 85 S r STE L TE L TM L TV L USPH S Z n Zn S ZP P M g fi\ ju m > <

xxi v Lea dmetaphosphat e Lea dorthophosphat e Lea dhydroxqpmxqpqwz n Lea dsulfid e Lea dsulfat e Porphobilinoge n Picocuri e (IO" 12 curie ) Proton-induce dX-ra y emission s Lo g o f th e reciproca l o f

th e hydroge n io n concentratio n Phosphat e io n Protoporphyri n Par t pe r billio n Par t pe r millio n Polyviny l chlorid e Re dbloo dcell ; erythrocyt e Ribonuclei c aci d Subcutaneou s Standar dcubi c mete r Secon d Seru mglutami c oxaloaceti c transaminas e Seru mglutami c pyruvi c transaminas e Sulfhydry l Sulfu r dioxid e Sulfat e io n Radioisotop e o f

strontiu m Short-ter mexposur e limi t Tetraethy l lea d Tetramethy l lea d Threshol dvalu e limi t U.S . Publi c Healt hServic e Zin c Zin c sulfid e Erythrocyt e zin c protoporphyri n Microgra m Microlite r Micromete r Greate r tha n Les s tha n Approximatel y

## 1 . SUMMAR Y AN D CONCLUSION S

1. 1 INTRODUCTIO N Th e firs t portio n o f

thi s documen t

i s devote dt o lea din th e environment : it s physica l an dchemica l properties ; it s monitorin g an dmeasuremen t in variou s environmenta l media ; it s environmenta l sources , emissions , an dconcentrations ; an dit s trans por t an dtransformatio n withi n th e environmen t (Chapter s 3 throug h7) . Chapter s 8 throug h1 3 ar e concerne dwit hth e effect s o f lea do n ecosystem s and , mos t important , o n huma n health . Amon g th e question s tha t hav e bee n specificall y addresse di n thi s documen t

are : 1 . Wha t ar e th e source s o f

lea din th e environ ment ? 2 . Wha t ar e th e route s an dmechanism s b y whic hlea dfro mthes e source s enter s th e body ? 3 . Onc e lea denter s th e body , wher e i s i t deposited ? 4 . Onc e lea di s in th e body , wha t ar e it s healt h effects ? 5 . Ar e ther e group s withi n th e populatio n tha t ar e particularl y vulnerabl e t o lead ? 6 . Wha t i s th e magnitud e o f

th e ris k i nterm s o f th e numbe r

o f person s expose din variou s subgroup s o f

th e population ? Thi s documen t

ha s bee n prepare dt o reflec t th e curren t stat e o f

knowledg e abou t

lea d— specifically , thos e issue s tha t ar e mos t

relevan t

t o establishin g th e objectiv e scientifi c dat abas e tha t will b e use dt o recommen da n ai r qualit y standar d fo r lea dtha t

wil l adequatel y safeguar dth e publi c health . 1.1. 1 Potentia l Exposur e t o Environmenta l Lea d Lea di s uniqu e amon g th e toxi c heav y metal s in tha t i t i s relativel y abundan t i n th e earth' s crust . Becaus e o f

it s eas y isolatio n an dlo w meltin g point , lea dwa s amon g th e firs t metal s t o b e use db y ma n thousand s o f

year s ago . Th e environmenta l signifi canc e o f lea di s aresul t

bot ho f it s utilit y an do f

it s abundance . Worl dproductio n exceed s 3. 5 millio n tons/year , afa r large r quantit y tha nth e productio n o f an y othe r

toxi c heav y metal . Lea di s presen t

infood , water , air , soil , dustfall , paint , an dothe r

material s withwhic hth e genera l populatio ncome s incontact . Eac ho f thes e repre sent s apotentia l pathwa y fo r huma n lea dexposur e vi ainhalatio n o r

ingestion . Th e actua l lea dconten t ineac hsourc e ma y var y b y severa l order s o f mag nitude . Potentia l exposur e pattern s ar e furthe r con founde db y huma nactivit y pattern s an db y difference s betwee nindoo r an doutdoo r

environ ments . Th e numbe r

an dexten t

o f variable s involve d mak e i t ver y difficul t

t o determin e th e actua l lea d intak e o f individual s inthei r

norma l environment . A s aresul t

o f centurie s o f

th e mining , smelting , an dus e o f

lea di nhuma nactivities , natura l back groun dconcentration s ar e difficul t t o determine . Geochemica l dat aindicat e tha t th e concentration s o f lea di nmos t surfac e material s inth e Unite dState s rang e fro m1 0 t o 3 0 pp m(figlg). Trac e amount s o f lea doccu r

naturall y inai r

an dwate r

a s aresul t

o f win dan drai nerosion , an dinai r a s aresul t

o f volcani c dusts , fores t

fires , se asalt , an dth e deca y o f radon . Natura l backgroun dconcentration s o f air born e lea dhav e bee n estimate dt o approximat e 0.000 6 fig Pb/m 3 o f

ai r (o r 5 x 10 7 /xg Pb/ g air) . Natura l concentration s infres hwate r hav e bee nesti mate dt o b e abou t

0. 5 /xg/lite r

o f wate r (abou t 5 x IO 4 fig Pb/ g water ) an dinocea nwate r abou t 0.0 5 fig Pb/lite r

o f wate r (abou t 4. 9 x 10" 5 fig Pb/ g water) . A s aconsequenc e o f th e extensiv e an d divers e use s o f

lead , presen t

concentration s o f

lea d inair , soil , an dwate r

ar e substantiall y highe r tha n thes e estimate dbackgroun dlevels . Nonurba n lea d concentration s averag e 0. 1 fig Pb/m 3 o f ai r (abou t 8 x 10 5 fig Pb/ g air) . Concentration s o f airborn e lea d inU.S . cities , a t

site s no t

conspicuousl y influence d b y majo r sources , averag e 1 fig Pb/m 3 o f ai r ( 8 x IO 4 fig Pb/ g air) . Expresse do n aweigh t basi s with respec t t o th e tota l suspende dparticulat e (TSP ) in th e air , thi s amoun t

i s approximatel y equivalen t t o 10 " fig Pb/ g TSP . Th e shap e o f

building s inurba n area s ma y caus e larg e horizonta l an dvertica l variation s in lea dcon 1- 1P.2 8

centrations . I n th e absenc e o f suc hstructures , th e vertica l gradien t

woul dusuall y b e relativel y small . Durin g period s o f

maximu mtraffi c densit y o n free ways , airborn e concentration s o f lea dimmediatel y adjacen t t o th e freeway s may reac h2 0 /xg/m 3 fo r a few hours . I n th e immediat e vicinit y o f larg e station ar y source s havin g n o ai r pollutio n controls , con centration s o f

airborn e lea dma y reac h30 0 /xg/m 3 unde r unfavorabl e meteorologica l conditions . Consequently , exposur e vi ainhalatio n o f airborn e inorgani c lea dparticulate s ma y var y b y afacto r o f at leas t 100 , dependin g o n locatio n an dactivit y pat terns . Th e smal l numbe r o f indoo r ai r lea dstudie s conducte dhav e show n indoo r concentration s t o b e one-thir do r

les s th e leve l measure doutdoors . In doo r level s var y widel y dependin g o n typ e o f struc ture , ai r conditioning , wind , etc . Dus t i s ageneri c ter man dconsequentl y imprecis e whe n use dt o describ e potentia l huma n exposure . Dus t in th e popula r

sens e usuall y refer s t o soli dpar ticle s tha t

hav e settle do n asurfac e an dtha t ca n b e readil y redisperse din th e atmosphere . I n a naero metri c sense , dus t

i s soli dparticle s suspende dinth e atmosphere ; consequently , i t i s an integra l par t

o f tota l suspende dparticulates . I n an occupationa l sense , dus t

may encompas s eve n large r particle s dis charge dint o th e wor k

environmen t

b y mechanica l means . Dustfal l i s ameasur e o f th e settle dparticu late , o r tha t deposite din o r

o n th e collectio n devices ; thu s dustfal l i s mor e closel y relate dt o th e popula r definitio n o f

dust . I n thi s document , dustfal l i s treate da s aseparat e pathwa y for potentia l ex posur e t o lea dvi aingestio n o f thes e settle dparticles , bu t onl y in aqualitativ e manner . Lea dconcentration s in dustfal l var y widel y with th e typ e an ddistributio n o f sources . Th e highes t value s occu r

in th e immediat e vicinit y o f source s an d diminis hrapidl y withdistance . Potentia l exposur e t o lea din dustfal l depend s o n th e tota l accumulatio n o f dus t in accessibl e areas . Th e accumulatio n de pend s o n th e depositio n rat e an dth e frequenc y an d efficienc y wit hwhic haccessibl e surface s ar e cleaned . Lea daccumulatio n resultin g fro mdeposi tio n fro mth e ai r

may b e augmente din th e home s o f lea dworker s b y transportatio n o f lead-containin g dust s fro mth e workplace . Th e leve l o f accumulate d lea dpotentiall y availabl e bot hindoor s an dout door s clearl y ma y var y b y on e t o tw o order s o f mag nitude . Concentration s o f

lea din solutio n in mos t urba n wate r supplie s ar e belo w 1 0 /xg Pb/lite r o f wate r (0.0 1 fig Pb/ g water) , bu t som e value s >5 0 /xg/lite r (th e U.S . Publi c Healt hServic e standar dfo r lea din drinkin g water ) hav e bee nreported . Suspende d

solid s contai n th e majo r fractio n o f

lea dinrive r waters . Concentration s of lea di n ta p wate r

ma y b e considerabl y highe r

tha nthos e i

nmunicipa l sup plies . Lea dvalue s a s hig ha s abou t 200 0 /xg/lite r hav e bee n reporte dfo r home s withlea dpipe s an d lead-line dstorag e tanks . Se aspray , rainwate r

leaching , an dflakin g pain t fro molde r

building s ca n contribut e significantl y t o lea dlevel s i

n adjacen t

soil . Direc t

ingestio no f

th e soi l o r o f re-entraine ddust , a s wel l a s ingestio n o f th e pain t chip s themselves , constitut e a nimportan t sourc e o f lea din area s wher e thes e condition s exist . Th e contributio no f

foo dt o huma nexposur e t o lea di s highl y variabl e an dno t wel l quantified . Esti mate s o f dail y intak e var y fro mabou t 10 0 t o 35 0 fig Pb/day . Recen t

studie s inth e Unit dState s estimat e th e adult s inges t

abou t 20 0 fig Pb/da y in food . Beverage s an dfood s tha t ar e store din lead-soldere d can s o r store do r

serve dinlead-glaze dpotter y hav e bee n identifie da s havin g hig hlea dcontent . Pro cesse dmil k

ha s bee n reporte dt o contai nmor e lea d tha n fres hcow' s mil k

—abou t 2 0 t o 4 0 /xg/lite r compare dt o abou t

5 t o 1 0 /xg/liter , respectively . If thes e value s ar e correct , processe dmil k coul db e a significan t

sourc e o f

lea dexposur e fo r

infants . Fo r adults , illicitl y distille dwhiske y an dol dauto mobil e batterie s use da s hom e heatin g fuel represen t tw o nonindustria l source s o f over t lea dpoisoning . O f muc hgreate r

significanc e a s ahealt hproblem , however , ar e variou s source s o f occupationa l ex posure . Worker s involve din uncontrolle d(withou t pollu tio ncontrols ) mining , smelting , an dmanufacturin g processe s wher e lea di s used , hav e th e highes t leve l o f potentia l exposure . Althoug hoccupationa l condi tion s hav e generall y bee nsubstantiall y improved , in som e case s lea dconcentration s i nth e ai r inwor k place s hav e bee nmeasure da t 100 0 /xg/m 3 o r greater . Th e majo r

occupationa l exposur e problem s occu r wher e adequat e hygien e program s hav e no t bee nimplemente do r

wher e individual s fai l t o tak e th e recommende dprecautions . Th e majo r rout e o f occupationa l exposur e i s th e inhalatio n o f dus t an d fumes ; in addition , dus t transporte do n clothin g fro mth e wor k

plac e t o th e hom e o r

automobil e ma y b e asignifican t

pathwa y o f

exposur e fo r

worker s an d thei r families . 1.1. 2 Source s o f

Environmenta l Lea d Th e mining , smelting , an dus e o f lea dinhuma n activitie s ha s significantl y altere dth e natura l distri butio n o f

lea din th e environment . Contaminatio n 1- 2ha s occurre dprimaril y i n th e vicinit y o f

source s an d i n densel y populate dareas . Th e lea duse di

n gasolin e antiknoc k

additive s represent s amajo r

fractio n o f

th e tota l U.S . lea d consumption , an dmoto r vehicl e emission s con stitut e th e majo r

sourc e o f

lea demission s t o th e at mosphere . I n 1975 , som e 189,00 0 M T o f lea d(1 6 percen t o f tota l production ) use din antiknoc k com pound s wer e converte dt o 142,00 0 M T o f at mospheri c emission s (8 8 percen t o f tota l lea demis sions) . A s aresul t

o f legislatio n settin g amaximu m limi t o n th e lea dconten t

o f gasoline , th e productio n an dus e o f

alky l lea dadditive s ha s decrease dinre cen t year s an dwil l probabl y continu e t o d o so . Base do n 197 5 estimates , combustio n o f wast e oi l an dincineratio n o f

soli dwast e ar e th e majo r contri butor s o f

lea demission s fro mstationar y source s (12,06 0 MT/year) . Thi s figur e represent s onl y tha t portio n o f

wast e oi l tha t

i s reprocesse dan dburne d in oil-fire do r

coal-fire dboiler s an dmunicipa l in cinerators . Othe r

stationar y source s of

lea demis sion s includ e iro n an dstee l productio nin plant s withpoo r pollutio n controls , primar y an dsecondar y smelting , batter y manufacturing , an dlea dalky l manufacturing . Lea dtha t may b e emitte dt o th e environmen t

fro mthes e operation s include s tha t in stac k emission s an dfugitiv e dusts . Contaminatio n fro mth e majo r

stationar y emitter s may determin e environmenta l concentration s fo r aradiu s o f

severa l kilometer s aroun dth e sources . Fugitiv e dust s ma y resul t in ahig hleve l o f

contaminatio n in th e im mediat e vicinit y o f

small , uncontrolle dbatter y re cyclin g operations . I n term s o f

mas s balance , lea dfro mmobil e an d industria l source s i s transporte dan ddistribute d mainl y vi ath e atmosphere . Certai n wast e disposa l operation s tha t

discharg e larg e amount s o f lea dint o soi l an dwate r

resul t onl y in highl y localize dcon tamination . Lea di s emitte dt o th e atmospher e pri maril y i n th e for mo f inorgani c particulates ; however , smal l amount s o f organi c vapor s hav e bee n reporte din th e vicinit y o f gasolin e servic e stations , garages , an dheav y traffi c areas . Thes e organi c vapor s underg o photochemica l decompositio n inth e atmosphere , bu t

the y ma y als o b e adsorbe do ndus t particl e surfaces . Base do n th e limite ddat aavailable , it i s estimate d tha t 7 5 percen t

o f th e particulat e lea demitte dfro m automobile s i s remove dfro mth e atmospher e in th e immediat e vicinit y o f

traffi c sources . Particle s smalle r

tha n thos e fro mmobil e sources , an demission s fro mtal l stack s will remai n airborn e longe r an db e transporte dove r greate r distances . Submicro n particle s ma y resid e inth e atmospher e a

wee k o r mor e befor e the y ar e remove db y dr y depositio n (diffusio n an dinertia l mechanisms ) an d b y precipitation . Th e tendenc y towar dunifor mver tica l an dhorizonta l distributio n(mixin g withcon comitan t distribution ) increase s wit han increas e in residenc e time . Th e chemistr y o f

lea daerosol s discharge dint o th e environmen t

ha s no t bee nstudie da s extensivel y a s th e chemistr y o f

som e o f th e othe r

majo r ai r pollu tants . Muc ho f

th e wor k

o nlea dparticulat e chemis tr y befor e 197 3 wa s limite dt o elementa l analyse s an ddi dno t

includ e analyse s o f

associate dions . In formatio n fro melementa l analyse s i s no t sufficien t t o permi t

athoroug hexaminatio n an dunder standin g o f

(1 ) transformatio nan dtranspor t pro cesse s tha t

occu r amon g th e environmenta l media , (2 ) mobilit y o f

lea din soils , (3 ) uptak e an ddistri butio no f lea dinplants , an d(4 ) th e overal l impac t o f lea dpollutio n o nhuma nhealt han decosystems . Informatio n i s neede do n th e chemica l form s an d interaction s o f

lea dan dit s tendenc y t o formcom pound s o f

lo w solubilit y withth e majo r anions . Onl y afew studie s hav e bee n conducte do nth e chemica l form s o f lea dinsoi l an dplants . The y sho w tha t th e principa l lea dformfoun dinsoil s i s sulfate , an dth e principa l formfoun din plant s i s phosphate . Lea ddissolve dfro mprimar y lea dsulfid e or e tend s t o combin e wit hcarbonat e o r sulfat e ion s t o formrelativel y insolubl e lea dcarbonat e o r lea dsul fate , o r t o b e absorbe db y ferri c hydroxide . Th e amoun t o f lea dtha t

ca nremai nin solutio n in wate r i s afunctio n o f

th e concentratio n o f

othe r ions , especiall y hydroge n ions . 1.1. 3 Monitorin g o f

Environmenta l Lea d Lea dha s bee nmonitore dinair , water , soil , food , an dbiologica l sample s suc ha s bloo dan durin e fo r man y years , bu t

th e accurac y o f

th e earl y samplin g an danalytica l technique s wa s quit e low . Conse quently , thes e earlie r

dat aca nb e use donl y in a qualitativ e o r

semiquantitativ e manner . Externa l contaminatio n ha s bee n th e majo r proble min al l samplin g procedures , particularl y in samplin g fo r bloo dlea danalyses . Samplin g an danalytica l techni que s fo r environmenta l lea dhav e enjoye dcon siderabl e improvemen t

an drefinemen t

inth e pas t few years . Som e o f

th e bes t methods , however , ar e tediou s an dexpensiv e an dar e availabl e onl y in relativel y specialize dlaboratories . Thos e analytica l technique s tha t

ar e les s sophisticate dproduc e result s o f limite dvalue . Th e capabilit y no w exist s fo r achievin g hig hprecisio n in lea dmonitoring ; bu t i n 1- 3P.3 0

genera l practice , precis e an daccurat e result s ar e difficul t t o obtain , particularl y for biologica l sam ples . Atomi c absorptio n spectroscop y i s th e mos t successfu l analytica l metho duse din recen t years . Th e primar y proble mface di n environmenta l monitorin g —

tha t is , samplin g an danalysi s —i s t o determin e th e typ e o f

monitorin g procedure s t o b e use dt o accomplis hspecifi c objectives , an dt o estab lis han dmaintai n adequat e qualit y control . Ambien t ai r monitorin g procedure s designe d specificall y fo r

assessin g populatio n exposur e pat tern s presen t

particularl y difficul t

problems . Tota l mas s concentration , particl e siz e distribution , an d chemica l compositio n o f lea daerosol s al l var y con siderabl y wit hspac e an dtime . I n usin g atmospheri c measurement s t o determin e populatio n exposures , huma n activit y pattern s ar e afurthe r complication . Thu s th e relationshi p betwee n measurement s o f at mospheri c concentratio n o f lead , duratio n o f

ex posure , an dincrementa l change s in bloo dlea dlevel s i s no t constant . Althoug hmeasurement s o f at mospheri c lea dlevel s ar e an essentia l ingredien t i n populatio n exposur e assessment , othe r indice s o f

ex posur e suc ha s bloo dlea dan dfre e erythrocyt e porphyri n (FEP ) level s ar e als o essentia l fo r th e characterizatio n of

huma n populatio n exoosures . Bloo dlea dma y b e measure db y severa l genera l technique s tha t

presentl y appea r

t o b e satisfactor y in th e hand s o f

qualifie danalyst s wh o hav e asophisti cate dtechnica l appreciatio n o f th e man y problem s associate dwit hmeasurin g a n elemen t tha t i s bot h presen t a t trac e level s an dubiquitousl y distribute d a s acontaminant . Extensiv e interlaborator y com parison s hav e demonstrate dth e nee dfo r standardiz in g methodology , usin g referenc e standards , an dob tainin g bloo dlea ddetermination s fro mthos e laboratorie s havin g highl y skille dpersonne l ac custome dt o handlin g alarg e numbe r o f samples . Th e presen t

existenc e o f

anumbe r

o f regiona l an d nationa l analytica l proficienc y testin g program s will hel p improv e th e qualit y o f analysi s an dth e reliabilit y o f

consequen t

clinica l an depidemiologi ca l data . Measurement s ofbiologica l indicator s suc h a s erythrocyt e porphyrin , 8-ALA , an d8-ALA D ar e als o aproblem . A standardize dmetho dexist s fo r urinar y ALA , an daprogra mi s underwa y in th e Unite dState s t o evaluat e standardization s o f methodolog y fo r

determinin g erythrocyt e porphyrin . 1. 2 EFFECT S O F LEA D O N MA N AN D HI S ENVIRONMEN T I n th e summar y materia l presente din th e preced in g section , attentio n wa s directe dt o al l th e ex posur e aspect s o f

lead . Th e biologica l aspect s o f th e lea dpollutio nproble mar e discusse dinthi s section . Thes e aspect s includ e no t onl y th e effect s o f

lea do n man , bu t als o it s effect s o n amyria do f ecosystem s tha t suppor t ma n an dcontribut e t o hi s genera l welfare . 1.2. 1 Effect s o f

Lea d o n Ma n Th e effect s o f

lea do n ma nar e summarize din se quentia l statement s o f

presen t knowledg e concern ing : 1 . Man' s metabolis mo f lead . 2 . Biologica l an dadvers e healt heffect s i n man . 3 . Effect s o f

lea do npopulations . 4 . Risk s ma nincur s fro mexposur e t o lead . 1.2.1. 1 METABOLIS M Metabolism , a s discusse dhere , encompasse s th e physiologica l processe s inma ntha t relat e t o absorp tion , distribution , excretion , an dne t retention . I t ca n b e discusse dinterm s o f route s o f

lea dexposur e an dth e physiologica l distinction s existin g withi n certai n segment s o f

th e populatio ntha t

modif y thes e processes . Specia l attentio n i s focuse do n th e factor s tha t may plac e th e developin g fetu s an dth e chil din acategor y o f

highe r ris k tha n th e adult . Nearl y al l lea dexposure s resul t fro minhalatio n an dingestion . Th e quantitie s o f lea dabsorbe dvi a thes e route s ar e determine db y man y factor s suc ha s th e physica l an dchemica l formo f th e lead , an dth e nutritiona l status , metaboli c activity , an dpreviou s exposur e histor y o f

thos e exposed . Clinica l studie s o n th e despositio n o f airborn e lea dparticulat e matte r inth e huma nrespirator y trac t sugges t tha t 3 0 ± 1 0 percen t

o f th e ambien t

ai r lea dparticulate s inhale dwil l b e deposited . O f th e lea dthu s deposite dinth e respirator y tract , it ha s bee n estimate dtha t

a s muc ha s 5 0 percen t

o r mor e i s absorbe dan denter s th e bloo dstream . Thi s deposi tio nma y var y considerably , dependin g o nparticl e siz e an dpatter n o f

respiration . Par t

o f th e fractio n deposite din th e respirator y tract , tha t portio n remove dvi ath e mucociliar y escalator , i s swallowe d an denter s th e gastrointestina l tract . Anima l studie s sugges t tha t th e relativ e efficienc y o f lun g clearanc e mechanism s ma y b e impaire da t hig hlevel s o f

air born e lead . I nchildren , approximatel y 4 0 percen t o f th e lea d take n int o th e gastrointestina l trac t i s absorbed , wherea s th e correspondin g valu e fo r adult s i s abou t 1 0 percent . I n on e stud y assessin g ne t gastro intestina l absorption , a n invers e relationshi p be 1- 4P.3 1

twee n calciu mintak e an dlea dabsorptio n wa s shown . Thi s relationshi p ha s als o bee n demonstrate d in experimenta l animals . I n discussin g th e route s b y whic hma n ma y b e ex pose dt o environmenta l lead , it i s importan t

t o dis tinguis hbetwee n primar y an dsecondar y exposur e t o atmospheri c lead . Primar y exposur e i s direct , an d secondar y i s indirect . Primar y exposur e t o airborn e lea dconsist s o f

it s direc t

inhalation , wherea s sec ondar y exposur e t o airborn e lea dconsist s o f inges tio n o f lea dtha t

i s o f atmospheri c origi n (tha t is , lea dtha t i s transporte db y th e airborn e rout e t o th e ingeste dmaterial) . Lea dma y contaminat e foodstuffs b y atmospheri c fallout , wit hsubsequen t adsorptio n ont o plan t sur face s o r absorptio n int o plants . Thi s contaminatio n ma y involv e primar y foo d(plant s consume db y man ) o r anima l foo dcrops . Soi l lea dtake n int o plant s ma y com e fro matmospheri c fallou t o r fro m leachin g fro mnatura l a s wel l a s industria l sources . Th e absorptio n o f

soi l lea db y plants , however , i s though t t o b e relativel y poor , althoug hdat ao n lea d accumulatio n in tre e ring s sugges t tha t absorptid n fro msoi l may occu r

in a t leas t som e plants . I nan y case , th e contributio n o f ai r lea dt o foo dlea dlevel s i s probabl y smal l o n th e basi s o f anationwid e foo d distributio n system ; bu t adequat e quantificatio n doe s no t yet exis t t o allo w precis e statement s o n thi s poin t t o b e made . I t

i s clear , however , tha t

commer cia l processin g raise s th e lea dconten t o f foo dsignifi cantly . Anothe r importan t

depo t o f lea din th e environ men t i s soi l o r

dust . Th e ultimat e sourc e o f thi s lea d varie s fro mplac e t o place ; i t ca n b e dustfal l fro mth e atmospher e (comin g fro meithe r stationar y o r mobil e sources) , o r

it ca n b e soi l o r

dus t int o whic h leade dpain t

ha s eroded . Thi s exposur e rout e i s though t t o b e mor e importan t

fo r childre n tha nfo r adults . Studie s hav e consistentl y show n association s betwee n soi l o r

dus t lea dlevel s an dbloo dlea d level s in childre n whe n suc hexposure s excee d100 0 ppm . I t i s though t

tha t lea dreache s th e childre n throug hthei r

norma l mouthin g behavior . Lea di s picke du p o n children' s hand s throug hthei r pla y an d i s the n transferre dt o thei r mouth s b y thei r

custom ar y habi t

o f puttin g thei r

hands , objects , an d material s in thei r

mouths . Ther e i s evidenc e demon stratin g arelationshi p betwee n dus t lea dan dlea do n fingers , bu t

a s ye t ther e i s n o direc t

evidenc e linkin g lea do n fingers wit hlea din th e blood . I n childre n withpica , however , th e importanc e o f thi s sourc e coul db e greatl y magnified . I t ha s bee n show n repeatedl y tha t level s o f lea din bloo dincreas e whe n ora l intak e increases , bu t

studie s d o no t

sho w aprecise , quantitativ e expres sio no f thi s relationship . Rather , anumbe r o f studie s sho w that , withsustaine ddail y ingestio no f 100 /xg o f lead , th e maximu mincreas e in steady-stat e level s o f bloo dlea drange s fro m6 t o 1 8 /xg/dl . Thes e variation s probabl y relat e t o nutritiona l factors , biologica l variability , unreporte dsource s o f ex posure , difference s in analytica l techniques , o r pre viou s exposur e histor y —o r t o acombinatio no f thes e factors . Sinc e children , particularl y infants , absor b alarge r

percentag e o f

lea dtha nadult s do , th e relativ e contributio no f ora l intak e i s undoubt edl y greate r

fo r them . Becaus e o f

highe r metaboli c activity , childre n als o inhal e relativel y mor e air born e lea dtha n d o adults . Therefore , th e contribu tio no f airborn e lea dt o tota l lea dintak e ma y b e greate r in childre ntha n inadults , bu t on e mus t

kee p inmin dtha t

childre n als o ea t

correspondingl y mor e o n abod y weigh t

basis . A numbe r

o f experimenta l anima l studie s hav e assesse dth e effect s o f

nutritio n an dothe r

factor s o n gastrointestina l absorptio n a s reflecte db y bloo d lea dlevels . I t

i s clea r fro mthes e studie s tha t th e statu s o f essentia l nutrient s suc ha s calcium , iron , phosphorus , fat , an dprotei ni s ver y important . Th e absorption , distribution , an daccumulatio no f lea din ma n i s convenientl y describe db y athree compartmen t

model . Th e first

compartment , cir culatin g re dbloo dcells , distribute s lea dt o th e othe r two , sof t tissue s (primaril y live r an dkidney ) an d bone , wher e it

accumulates . Thi s accumulatio n begin s in feta l lif

e a s aresul t

o f transplacenta l trans fer . I nnonoccupational ^ expose dadults , suc h storag e approache s 9 5 percen t o f th e tota l bod y burden . Th e skeleto n i s arepositor y o f lea dtha t

re flect s th e long-ter mcumulativ e exposur e o f th e in dividua l ; bod y fluid s an dsof t tissue s reflec t

mor e re cen t exposure . Sinc e th e nonaccumulatin g bod y burde n in sof t tissue s ha s agreate r

toxicologica l significanc e tha n tha t fractio n sequestere din bone , th e mobilizabl e lea dburde n i s amor e importan t concep t tha n tota l bod y burden . I nthi s connection , chelatabl e urinar y lea dha s bee n show nt o provid e a ninde x o f th e mobil e portio n o f

th e tota l bod y burden , a s ha s th e lea dleve l in blood , whic hi s th e mor e generall y use d indicato r o f interna l dose . Ther e i s atim e fram e inwhic hchange s in ex posur e registe r

a s aperturbatio n in th e bloo dlea d level . Clinica l studie s sho w tha t (1 ) acontrolle d dail y intak e result s inaconstan t concentratio n o f bloo dlea dafte r

11 0 days , dependin g o n th e ex 1-5P.3 2

posur e setting , an d(2 ) asingle , acute , controlle dex posur e yielde dabloo dlea dhalf-lif e o f abou t 2 day s compare dt o approximatel y 1 7 day s in th e cas e o f repeate dexposures . Followin g cessatio n o f exposur e afte r lon g exposur e period s (e.g. , years) , however , th e half-lif

e o f bloo dlea dca n b e expecte dt o b e sub stantiall y longe r

tha n 1 7 days . Feca l excretio n represent s th e majo r rout e b y whic hingeste dlea di s eliminate dfro mth e body . Thoug hexcretio n b y thi s rout e i s usuall y muc h greate r tha n b y urinar y elimination , th e tota l fecal lea dconten t

include s unabsorbe dlea da s it s majo r component . 1.2.1. 2 BIOLOGICA LAN D ADVERS E HEALT H EFFECT S O FLEA D I N MA N Ther e ar e variou s physiologica l level s an dex posur e range s a t

whic hth e effect s o f

lea din ma noc cur . Furthermore , lea daffect s ma n at th e sub cellular , cellular , an dorga n syste mlevels . Amon g subcellula r

components , bot hnucle i an d mitrochondri agenerall y sho w th e mos t pronounce d response s t o cellula r invasio n b y lead . Th e mitochondria , however , ar e mos t vulnerabl e an d sustai n th e greates t

functiona l impairment . Mitochondria l injury , bot hin term s o f cellula r energetic s an dmorphologica l aberration , ha s bee n show n in anumbe r

o f experimenta l animals . I n man , th e evidenc e fo r

mitochondria l impairmen t ha s bee n morphologica l rathe r

tha n functional . Thos e sub cellula r change s observe dar e primaril y th e develop men t o f nuclea r inclusio n bodie s in kidne y cell s a s wel l a s mitochondria l change s in rena l tubula r cell s in person s expose doccupationally . An y discussio n o f

th e subcellula r

effect s o f

lea d mus t conside r th e questio n o f

chromosoma l aberra tion s an dcarcinogenesis . A t th e presen t

time , n o conclusiv e statement s ca n b e mad e abou t th e induc tio n o f chromosoma l damag e b y lead . Th e literatur e o n thi s issu e eithe r

yield s conflictin g informatio no r describe s studie s tha t

ar e difficul t

t o compar e with eac hother . Som e experimenta l anima l studie s relat e th e developmen t

of cance r t o relativel y hig hdose s o f lead , bu t a s i s tru e in th e cas e o f

othe r suspecte dcar cinogens , ther e ar e n o dat acorroboratin g thes e find ings in man . Amon g th e systemi c an dorgani c effect s o f lead , importan t

area s ar e it s hematologic , neurobe havioral , an drena l effects . Attentio n mus t als o b e given , however , t o th e effect s o f lea do n reproduc tio n an ddevelopmen t

a s wel l a s it s hepatic , en docrine , cardiovascular , immunologic , an dgastro intestina l effects . A numbe r o f significan t

effect s o f

lea do n th e hematopoieti c syste minhuman s hav e bee n observe d in lea dpoisoning . Thes e effect s ar e prominen t in clinica l lea dpoisonin g bu t ar e stil l presen t

t o a lesse r degre e in person s wit halowe r leve l o f lea d exposure . Anemi ai s aclinica l featur e o f lea dintoxication , resultin g fro mbot hincrease derythrocyt e destruc tio nan ddecrease dhemoglobi nsynthesis . I n children , athreshol dbloo dlea dleve l fo r produc tio no f thes e symptom s o f

anemi ai s approximatel y 4 0 fig Pb/dl , an dth e correspondin g valu e fo r adult s appear s t o b e 5 0 /xg Pb/dl . Hemoglobi n synthesi s i s impaire db y lea dvi ain hibitio no f

synthesi s o f

th e globi nmoiet y an dinhibi tio na t severa l step s inth e synthesi s o f heme . Th e ste p mos t

sensitiv e t o lea din th e hem e syntheti c pathwa y i s tha t

mediate db y th e enzym e 8-aminolevulini c aci ddehydratas e (8-ALAD) , whic hconnect s tw o unit s o f 8-aminolevulini c aci d (8-ALA ) t o formporphobilinogen . Th e resul t i s an increas e inplasm aleve l an denhance durinar y ex cretio n o f

8-ALA . Als o inhibite db y lea di s th e in corporatio no f

iro n int o protoporphyri n t o for m heme , th e prostheti c grou p o f hemoglobin . Thi s result s inth e accumulatio no f coproporphyrin , whic hi s excrete dinth e urine , an do f protopor phyrin , whic hi s retaine dinth e erythrocytes . Th e overal l effec t

o f lea di s ane t

decreas e inhem e syn thesis . (Thi s als o derepresse s 8-AL A synthetase , th e enzym e involve din th e firs t ste p o f hem e synthesis. ) Inhibitio no f

8-ALA D occur s at

extremel y lo w bloo dlea dlevel s an dha s bee n show nt o star t at a bloo dlea dleve l a s lo w a s 1 0 /xg/dl . Thoug hth e health-effec t

significanc e o f

inhibitio n a t

abloo d leve l o f 1 0 /xg/d l i s ope nt o debate , th e increase d urinar y 8-AL A excretio n tha t occur s withincreasin g inhibitio nat

4 0 /xg/d l i s accepte da s ameasur e o f probabl e physiologica l impairmen t in vivo. Thi s threshol dleve l fo r

urinar y 8-AL A excretio n (4 0 /xg/dl ) appear s t o b e tru e fo r bot hadult s an d children . A nincreas e infre e erythrocyt e protoporphyri n (FEP ) occur s a t

bloo dlea dlevel s o f

1 6 /xg/d l in children . I n adul t

females , thi s threshol di s probabl y similar . I n adul t

males , th e valu e i s 2 0 t o 2 5 /xg/dl . Th e precis e threshol dfo r coproporphyrin , whil e no t wel l established , i s probabl y simila r t o tha t fo r 8-ALA . Elevatio no t

fre e erythrocyt e protopor phyri n ha s th e sam e implication s o f physiologica l impairmen t

in vivo a s urinar y 8-ALA . T o th e exten t tha t th e protoprophyri n elevatio n i s alikel y indica to r o f th e impairmen t

o f mitochondria l functio n i n 1- 6erythroi dtissue , it ma y b e eve n mor e important . Fo r thes e reasons , physician s wh o participate din th e developmen t

o f th e 197 5 statemen t

b y th e Cente r

fo r Diseas e Contro l an dth e America n Academ y o f Pediatric s reache daconsensu s tha t elevate dFE P shoul db e use da s a n indicato r o f increase dexposur e t o lead . Th e effect s o f

lea do n th e nervou s syste mrang e fro macut e intoxicatio n an dfata l encephalopath y t o subtl e behaviora l an delectrophysiologi c change s as sociate dwit hlowe r

leve l exposures . Change s throughou t

th e rang e o f

effect s ar e relate dt o bloo d lea dlevels . I t woul dappea r

tha t surprisingl y lo w level s o f bloo dlea dma y sometime s b e associate dwithth e mos t extrem e effect s o f

lea dpoisonin g —servere , ir reversibl e brai n damag e a s indexe db y th e occur renc e o f acut e o r chroni c encephalopath y symptom s and/o r death . Thoug hfor

mos t adult s suc hdamag e doe s no t occu r unti l bloo dlea dlevel s substantiall y excee d120 /xg/dl , som e evidenc e suggest s tha t acut e encephalopath y an ddeat hma y occu r in som e adult s at bloo dlea dlevel s slightl y belo w 10 0 /xg/dl . Fo r children , th e effectiv e bloo dlevel s fo r producin g en cephalopath y o r

deat har e lowe r

tha n fo r

adults , withsuc heffect s bein g see n somewha t mor e often , startin g a t

approximatel y 10 0 /xg/dl . Again , however , evidenc e exist s fo r th e occurrenc e o f encephalopath y in aver y fe w case s at

lowe r levels , dow n t o abou t

8 0 /xg/dl . I t shoul db e note dtha t

onc e encephalopath y oc curs , deat hca n b e afrequen t outcome , regardles s o f th e leve l o f

medica l interventio n a t th e tim e o f

th e acut e crisis . I t

i s als o crucia l t o cit e th e rapidit y with whic hacut e encephalopath y o r deat hca ndevelo p in apparentl y asymptomati c individual s o r inthos e ap parentl y onl y mildl y affecte db y elevate dbod y bur den s o f lead . I t i s no t unusua l fo r

rapi ddeterioratio n t o occur , wit hconvulsion s o r com asuddenl y appear in g an dprogressin g t o deat hwithi n 4 8 hr . Thi s suggest s tha t

a t hig hbloo dlea dlevels , eve n whe n individual s ar e asymptomatic , rathe r sever e neura l damag e ca n exis t withou t over t manifesta tions . Studie s sho w tha t apparentl y asymptomati c childre n wit hhig hbloo dlea dlevel s o f ove r 8 0 t o 10 0 /Ag/d l ar e permanentl y impaire dcognitively , a s ar e individual s wh o surviv e acut e episode s o f lea d encephalopathy . Thes e studie s ten dt o suppor t th e hypothesi s tha t

significan t

if albei t subtl e change s in neura l functio n occu r

a t wha t wer e onc e considere d tolerabl e bloo dlea dlevels . Othe r evidenc e tend s t o confir mrathe r wel l tha t som e typ e o f

neura l damag e doe s exis t inasympto mati c children , an dno t necessaril y onl y a t

ver y hig h level s o f bloo dlead . Th e bod y o f studie s o nlow - o r moderate-leve l lea deffect s o n neurobehaviora l function s presen t

overal l a n impressiv e arra y o f dat a pointin g t o tha t

conclusion . Severa l well-controlle d studie s fin deffect s tha t ar e clearl y statisticall y sig nificant , an dman y other s repor t nonsignifican t

bu t borderlin e effects . Sinc e som e o f th e effect s a t

lo w level s o f lea dexposur e discusse dinthi s documen t ar e o f asubtl e nature , th e finding s ar e no t alway s strikin g in individua l cases . Nevertheless , whe nth e result s o f

al l o f th e studie s o nneurologi c an dbe haviora l effect s at

subclinica l exposure s ar e con sidere dina n overal l perspective , arathe r consisten t patter no f

impaire dneura l an dcognitiv e function s appear s t o b e associate dwithbloo dlea dlevel s belo w thos e producin g th e over t symptomatolog y o f lea dencephalopathy . Th e bloo dlea dlevel s a t whic h neurobehaviora l deficit s occu r i n otherwis e asymptomati c childre n appea r t o star t a t arang e o f 5 0 t o 6 0 /xg/dl , althoug hsom e evidenc e tentativel y suggest s tha t

suc heffect s may occu r

at slightl y lowe r level s fo r som e children . Dat aobtaine dfor

th e effect s o f

lea do nth e ner vou s syste min laborator y animal s ar e als o quit e ex tensive . Encephalopath y i s produce db y high-leve l perinata l exposur e t o lead ; indifferen t species , thi s occur s t o varyin g degree s a s characterize db y th e relativ e exten t

o f neurona l degeneratio n an d vasculopathy . I t

seem s clea r

tha t th e anima l dat a suppor t th e contentio n tha t

th e developin g organis m represent s th e populatio na t greates t ris k fo r centra l nervou s syste mtoxicity . Ther e i s als o goo devidenc e tha t perinata l ex posur e o f

laborator y animal s t o lea da t moderat e level s will produc e delay s in bot hneurologica l an d sexua l development . Sinc e thes e effect s hav e bee n demonstrate dt o occu r in th e absenc e o f

eithe r undernutritio n o r

growt hretardation , it ha s bee n suggeste dtha t

the y ma y represen t

mor e o r les s direc t effect s o f lea dinth e respectiv e systems . I nanima l studies , locomoto r activit y ha s bee n th e mos t commonl y use dbehaviora l inde x o f lea dtox icity . Dat aindicat e tha t increase dlocomoto r

ac tivit y in youn g animal s occur s onl y a t moderatel y hig hexposur e levels . I t

ma y be , invie w o f

th e levels , tha t th e change s in activit y currentl y reporte din laborator y animal s ar e mor e diagnosti c o f apost encephalopathi c hyperactivit y tha n o f subclinica l effects . Interestingly , th e reactivit y change s see n in olde r animal s ar e associate dwithmuc hlowe r bloo d lea dlevels . Finally , report s o n th e effect s o f lea dexposure s o n 1-7P.3 4

th e acquisitio n and/o r performanc e o f

operan t response s indicat e tha t

perinata l exposur e t o moder at e o r lo w level s o f

lea dmay disrup t

thi s typ e o f behavior . Thu s a t

bloo dlea dlevel s rangin g fro m3 0 t o 8 0 /xg/dl , cognitiv e functio n appear s t o b e dis rupte din animals . Excessiv e lea dexposur e ca n resul t in acut e a s wel l a s chroni c rena l injur y in man . Th e acut e rena l effect s o f lea dar e see n in person s dyin g o f acut e lea d poisonin g wher e lead-induce danemi aand/o r encephalopath y ma y als o b e seen . Thes e effect s ar e manifeste db y nonspecifi c degenerativ e change s in rena l tubula r

linin g cells , cloud y swelling , an dsom e degre e o f

cellula r necrosis . I n addition , nuclea r in clusio n bodie s for min tubul e cells , an dther e ar e functiona l an dultrastructura l change s in tubula r mitochondria . Aminoaciduria , glycosuria , an d hyperphosphaturi aar e noted , wit haminoaciduri a bein g arathe r

consisten t

featur e o f

tubula r damag e in children . Thes e effect s ar e usuall y reversible . I t i s no t possibl e a t

th e presen t

tim e t o stat e wha t

leve l o f lea din bloo di s associate dwithaminoaciduri ao r an y o f th e othe r

specifi c indice s o f

acut e rena l injury . Prolonge dlea dexposur e in human s ca n resul t in chroni c lea dnephropathy . Th e patholog y o f thes e chroni c change s i s differen t fro mtha t

see n in acut e rena l injury . I t

i s characterize db y th e gradua l onse t of pronounce darterioscleroti c changes , fibrosis , glomerula r

atrophy , hyalin e degeneration , an d reductio n in kidne y size . Thi s ca n b e aprogressive , irreversibl e conditio n resultin g in deat hfro mrena l failure . A threshol do f lea dexposur e fo r

thes e chroni c change s canno t ye t b e stated , however , a s a resul t o f th e typica l inaccessibilit y o f dat aneede dfo r th e accurat e assessmen t of th e precedin g long-ter m exposur e history . Considerabl e evidenc e fo r th e advers e effect s o f lea do n reproductio n an ddevelopmen t in ma nha s bee n accumulatin g fo r man y years . Man y o f th e earl y dat ao n th e inductio n o f abortions , stillbirths , an dneonata l death s wer e fo r occupationall y ex pose dpregnan t

women , wher e suc heffect s wer e demonstrate dat

hig hbloo dlea dlevels . O f mor e pressin g presen t

interes t ar e certai n recen t

studie s in thi s are afocusin g o n tw o aspect s o f th e effect s o f

lo w t o moderat e lea dexposur e o n reproduction : gameto toxicit y an dpost-conceptio n events . I n regar dt o potentia l lea deffect s o n huma n ovaria n function , on e stud y ha s show n tha t short ter mexposur e a t

ambien t ai r level s o f

les s tha n 7 /ig/m 3 ma y caus e an increas e in th e anovula r cycl e an ddisturbance s in th e lutei n phase . Thi s study , however , require s confirmatio n befor e conclusiv e statement s ca n b e made . Anothe r recen t repor t in volvin g occupationa l exposur e similarl y suggest s tha t moderatel y increase dlea dabsorptio n (bloo d lea dmea n = 52. 8 /ig/dl ) ma y resul t indirec t testicula r impairment ; however , th e desig n o f thi s stud y i s suc htha t

thi s observatio nals o require s verification . Thus , i t i s clea r tha t gametotoxic , embryotoxic , an dteratogeni c effect s at agros s leve l ca n b e in duce din laborator y animal s withlead , bu t it shoul d b e emphasize dtha t

th e productio no f

suc heffect s probabl y require s acute , hig hexposures . Unfor tunately , apaucit y o f informatio n exist s o nth e teratogenicit y an ddevelopmenta l toxicit y o f chroni c lo w o r moderat e lea dexposures . Availabl e dat ao n th e subjec t

d o suggest , however , tha t chroni c low leve l lea dexposur e may induc e postnata l develop menta l delay s in rats . Ou r presen t knowledg e abou t

th e effect s o f

lea din ma n o nth e hepatic , cardiovascular , immunologic , an dendocrin e system s i s fragmentary , renderin g it difficul t t o mak e an y conclusiv e statement s abou t quantitativ e relationships . Fo r example , effect s o f lea do n th e endocrin e syste mar e no t wel l define da t present . Thyroi dfunctio n in man , however , ha s bee n show nt o b e decrease dinoccupationa l plumbism . Also , effect s o f

lea do n pituitar y an dadrena l func tio nin ma nhav e bee n observed , wit hdecrease d secretio no f

pituitar y gonadotrophi c hormone s bein g note dbu t

adrena l functio n effect s bein g ales s con sisten t finding . Th e respons e o f

th e hepati c syste mt o lea dha s no t bee n wel l characterize dinman ; instead , muc ho f th e literatur e deal s withhepati c effect s in experimenta l animals . Lead-poisone danimal s sho w significantl y impaire ddrug-metabolizin g activities , thu s suggest in g a neffec t

o n th e hepati c mixed-functio n oxidas e system . Sinc e detoxificatio ninanimal s depend s o n th e microsoma l hem e protein , cytochrom e P450 , an dsinc e hem e biosynthesi s i s impaire dinlea dex posure , suc ha n effec t

i s alogica l consequenc e o f lea dpoisoning . O f mor e direc t

interes t in term s o f

reproductiv e efficienc y ar e th e effect s o f lea dexposur e o npreg nan t wome n—no t

onl y o n feta l healt han ddevelop ment , bu t als o o n materna l complications . Placenta l transfe r o f lea dha s bee ndemonstrate dbot hb y feta l tissu e analysi s an dcompariso no f newbor n umbilica l cor dbloo dlea dwithmaterna l bloo dlead . On e mus t no t onl y conside r

th e resultin g absorptio n o f lea db y th e fetus , bu t

als o th e specifi c point s in embryoni c developmen t

a t whic hexposur e occurs . Feta l tissu e uptak e o f

lea doccur s b y th e en do f th e firs t tri 1 -mester , whic hma y b e asensitiv e perio di n

embryoni c developmen t o f th e nervou s system . Studie s comparin g umbilica l cor dbloo dlea d level s in newborn s withsimultaneousl y sample d materna l bloo dsho w tha t th e newbor n an dmaterna l level s ar e closel y correlated . Th e studie s hav e als o show n tha t

th e newborn s o f

mother s in a n urba nset tin g ar e bor n wit hgenerall y highe r bloo dlevel s tha n thos e o f correspondin g newborn s fro mrura l areas . Tha t th e prenata l exposur e o f th e fetu s t o lead , eve n in th e absenc e o f

teratogeni c effects , i s o f conse quenc e fo r

advers e healt heffect s i s show n b y studie s relatin g feta l level s t o change s in feta l hem e syn thesi s an dt o th e incidenc e o f prematur e births . Som e suggestion s in th e literatur e tha t hem e biosynthesi s in anewbor n ma y b e affecte drequir e confirmation . I n evaluatin g materna l complication s relate dt o lea dexposure , on e mus t conside r tha t pregnanc y i s a physiologica l stres s tha t may plac e th e pregnan t woma n a t

highe r ris k t o lea dexposur e effects . Bot h iro n an dcalciu mdeficienc y increas e th e suscep tibilit y o f

an individua l t o lea dtoxicity . Wome n hav e a n increase dris k o f bot hdeficiencie s durin g pregnanc y an dpostpartum . Som e availabl e bu t

unconfirme dinformatio nin dicate s tha t

th e ris k o f prematur e ruptur e o f

th e am nioti c membran e ma y b e highe r in case s o f

elevate d exposur e tha n in age-matche dcontrol s withou t suc h exposure . Th e literatur e leave s littl e doub t abou t th e deleteriou s healt heffect s o f lea do n reproduction , bu t mos t report s d o no t

provid e specifi c description s of exposur e level s at

whic hspecifi c reproductiv e effect s ar e noted . Materna l bloo dlea dlevel s o f approximatel y 3 0 /xg/d l ma y b e associate dwit ha highe r incidenc e of

prematur e deliver y an dpre matur e membran e rupture , bu t thes e observation s requir e confirmation . I n adul t males , level s o f

5 0 t o 8 0 /xg/d l ma y b e sufficien t t o induc e significan t spermatotoxi c effects , bu t thi s effec t

ha s no t bee n conclusivel y demonstrated . Lea dha s no t

bee n show n t o b e teratogeni c inman , bu t anima l experiment s hav e demonstrate dtha t hig h level s o f lea dtha t

ar e stil l compatibl e wit hlif e in sexuall y matur e animal s interfer e wit hnorma l reproduction ; thes e studie s includ e assessmen t o f lea deffect s in bot hparents . Reductio n in offsprin g number , weight , an dsurviva l an da n increas e in feta l resorptio n i s aconsisten t findin g in rats , mice , an d othe r specie s ove r

arang e o f

high-leve l lea dex posures . Effect s o n offsprin g hav e bee n show n t o in volv e th e gametotoxi c effec t o f lea do n male s a s wel l a s female s in anumbe r o f anima l species . A t lea dlevel s presentl y encountere din occupa tiona l exposure , n o significan t cardiovascula r

effect s ar e discernible . Clinica l dat afor childre nsufferin g fro mchroni c lea dpoisonin g resultin g in deat hindi cat e tha t extensiv e myocardia l damag e occurs . I t i s no t clea r tha t th e associate dmorphologica l change s ar e aspecifi c respons e t o lea dintoxication . How ever , inman y instance s wher e encephalopath y i s present , th e electrocardiographi c abnormalitie s dis appea r withchelatio n therapy . Ther e ar e insufficien t

dat apertainin g t o th e effect s o f elevate dbloo dlea dlevel s an dth e incidenc e o f in fectiou s disease s inma nt o allo w th e derivatio n o f a dose-respons e relationship . Neithe r ca n adose respons e relationshi p b e define dfo r th e effect s o f elevate dbloo dlea dlevel s o nth e gastrointestina l tract , eve n thoug hcoli c i s usall y aconsisten t earl y sympto mo f

lea dpoisonin g inadult s expose d occupationall y an dininfant s an dyoun g children . 1.2. 2 Effect s o f

Lea d o n th e Ecosyste m A s anatura l constituent , lea ddoe s no t usuall y pos e athrea t

t o ecosystems . Th e redistributio n o f naturall y occurrin g lea di nth e environment , how ever , ha s no w cause dsom e concer ntha t lea dma y represen t apotentia l threa t

t o th e ecosystem . Fo r

ex ample , studie s hav e show nafivefol dincreas e in lea d intre e ring s durin g th e las t 5 0 years ; thi s accumula tio nmay serv e a s ausefu l inde x o f pattern s o f

en vironmenta l lea daccumulation . Ther e ar e als o documente deffect s o f lea do n domesti c animals , wildlife , an daquati c life . Lea d poisonin g indomesti c animal s produce s varyin g degree s o f

derangemen t

o f th e centra l nervou s system , gastrointestina l tract , muscula r system , an d hematopoieti c system . A s i s tru e in man , younge r animal s appea r

t o b e mor e sensitiv e tha nolde r ones . Wildlif e ar e expose dt o awid e rang e o f lea d levels . Toxi c effect s fro mingestio no f lea dsho t

hav e lon g bee n recognize da s amajo r healt hproble min waterfowl . Severa l specie s o f smal l mammal s trap pe dalon g roadway s wer e teste dfo r lea dconcentra tions . Al l bu t

on e o f th e specie s livin g i n habitat s ad jacen t t o high-volum e traffi c showe dhig hcon centration s o f

lead . Thi s wa s especiall y tru e i nurba n areas . Lea dtoxicit y inaquati c organism s ha s bee n ob serve dan dstudie dexperimentally . Symptom s o f chroni c lea dpoisonin g in fis hinclud e anemia , possi bl e damag e t o th e respirator y system , growt hinhibi tion , an dretardatio n o f sexua l maturity . Ther e i s evidenc e tha t

lea dha s bot hharmfu l an d beneficia l effect s o nplants . Plant s ar e expose dt o lea dthroug hth e leaves , stems , bark , o r roots , an d 1-9P.3 6

th e exten t

o f th e effect s depend s o n th e form , amount , an davailabilit y o f tha t lead . Th e morpholog y o f

th e plan t

surfac e play s th e majo r rol e in determinin g th e typ e an dquantit y o f materia l re taine db y plants . Meteorologica l factor s ar e als o im portan t in determinin g th e fat e o f lea dtha t

come s int o contac t

wit hplants . Larg e deposit s o f iner t in solubl e meta l compound s o n th e leave s ar e probabl y o f littl e consequenc e t o plants , a s th e mos t importan t facto r i s th e solubilit y o f

th e metal . Thus , becaus e in organi c lea dcompound s ar e generall y o f lo w solubility , ther e i s littl e incorporatio n an daccumu latio n withi n th e leave s o f plants . Th e majorit y o f

studie s reportin g lea dtoxicit y in plant s hav e bee n conducte dwithplant s grow nin artificia l nutrien t

culture . Thes e studie s hav e pro mote dth e concep t

tha t th e effect s o f

lea dar e depen den t o n avariet y o f

environmenta l factors , includin g anion s an dcation s withi n th e plan t an din th e growt h media , an dth e physica l an dchemica l characteristic s o f th e soi l itself . A s lea dinteract s wit hman y environmenta l factors , specifi c correlation s betwee n lea deffect s an dlea dconcentration s ar e extemel y difficul t t o predict . 1. 3 EFFECT S O F LEA D O N POPULATION S Th e frequenc y distributio n o f bloo dlea dlevel s in homogeneou s huma n population s ha s almos t invari abl y bee n foun dt o b e lognormal . Mos t dat aset s of homogeneou s population s displa y ageometri c stan dar ddeviatio n (GSD ) o f 1. 3 t o 1.5 . Thi s woul d roughl y correspond , fo r example , t o a n arithmeti c standar ddeviatio n o f

5. 3 t o 8. 5 /xg/d l a t

amea n bloo dlea do f

2 0 /xg/dl . Fro mth e lognorma l distribution , give n amea n bloo dlea dleve l an destimate dGSD , it i s possibl e t o predic t th e percentag e o f

apopulatio n whos e bloo d lea dlevel s excee do r

fal l belo w aspecifie dvalue . I t i s als o possibl e t o estimat e th e probabl e increas e in mea n bloo dlea dlevel s fo r apopulatio n expose dt o a specifi c increase s in environmenta l lead . Thes e tw o procedures , use dtogether , provid e ametho db y whic hai r qualit y standard s ma y b e chose n t o protec t th e healt ho f

th e population . Bloo dlea dlevel s var y wit hgeographi c location . The y ar e lowes t

in som e remot e populations , highe r in mos t rura l settings , highe r

stil l i n suburba n areas , an dhighes t

i n inner-cit y areas . Thi s gradien t follow s th e presume dlea dexposur e gradient . Bloo dlea d value s als o var y b y age , sex , an drace , althoug hi na somewha t

mor e comple x fashion . Generally , youn g childre n hav e th e highes t levels , wit hlittl e differenc e note dbetwee n sexe s a t thi s age . I nolde r segment s o f th e population , afte r

eliminatio n o f

oc cupationa l exposur e inlea dworkers , male s stil l hav e ahighe r

bloo dlea dtha nfemales . Onl y limite d publishe ddat aar e availabl e comparin g th e bloo d level s of th e variou s racia l an dethni c group s o f th e population . Thes e dat asugges t tha t urba nblack s hav e highe r

lea dlevel s tha n whites , wit hlevel s in Puert o Rican s frequentl y bein g intermediate . Result s o f

th e numerou s studie s o f environmenta l lea dexposure s o f

ma n hav e indicate dstrongl y tha t ma ndoe s indee dhav e cumulativ e uptak e fro meac h sourc e t o whic hh e i s exposed . Equall y important , thes e studie s hav e show n tha t th e bloo dlea dleve l represent s asummatio nof th e absorptio n fro meac h o f thes e sources . Dat afo r th e tw o mos t

widesprea denvironmenta l source s o f

lea dothe r

tha n foo dpermi t

summar y statement s concernin g thei r quantitativ e relation shi p withbloo dlea dlevels : ai r an dsoil/dust . Bloo d lea dlevel s wer e foun dt o increas e withrisin g ai r lea dconcentrations . Th e relationship s wer e foun dt o b e eithe r log-linea r

o r log-log . Evaluatio n o f th e equation s a t

variou s commonl y observe dai r lea d level s reveale dtha t

th e rati o betwee nchange s i n bloo dan dchange s inai r lea dvarie dgenerall y be twee n1 an d2 an dtha t it wa s no t constan t ove r th e rang e o f ai r exposures . Thi s implie s tha t a nincreas e o f 1 /xg/m 3 o f

ai r lea dresult s ina n averag e increas e o f 1 t o 2 /xg/d l in bloo dlea dlevels . Suggestiv e evi denc e indicate s tha t

childre n ma y hav e highe r ratio s tha nadult s an dtha t

male s ma y hav e highe r ratio s tha n females . On e o f th e mos t extensiv e dat aset s o n bloo dlea d inchildre n come s fro mastud y b y th e U.S . Depart men t o f Housin g an dUrba n Developmen t o n th e bloo dlea dvalue s o f approximatel y 180,00 0 childre ni nNe w Yor k

City . Thes e dat acovere dth e perio dMarc h197 0 throug hDecembe r 1976 . A pre liminar y analysi s o f

thes e importan t

researc hfind ings wa s presente dt o th e Subcommitte e o nLea do f EPA' s Scienc e Advisor y Boar dinOctobe r 1977 . Th e followin g pattern s appea r t o b e indicate db y thes e data : 1 . Ther e i s adefinit e differenc e in bloo dlea d value s fo r

racia l an dethni c groups , black s havin g highe r

mea nlea dlevels , an dHis panic s an dwhite s havin g lowe r levels . 2 . Analysi s show s tha t th e mea n bloo dlea d leve l i s relate dt o rac e an dethnicity , age , an dyea r o f sampling . Thi s ag e dependenc e i s simila r fo r al l years : Th e 1 - t o 12-month-ol d grou p ha s th e lowes t

levels , an dgenerall y th e maximu mi s foun din 2 - t o 4-year-olds . 1-1 03 . Ther e wa s aconsisten t decreas e o f

mea n bloo dlea dlevel s ove r th e cours e o f

th e study . Thi s decreas e wa s coinciden t wit ha reductio n in lea dlevel s in gasolin e in th e Ne w Yor k

Cit y area . 4 . Ther e appear s t o b e alikel y correspondin g decreas e in th e ai r

lead . However , it

shoul d b e pointe dou t

tha t ai r lea ddat afo r

Ne w Yor k Cit y ar e spars e an dtha t it woul db e un wis e t o assum e tha t

th e ai r lea dleve l a s measure dat

asingl e locatio n woul db e th e sam e fo r al l locations . Becaus e o f th e heigh t o f th e sampler , i

t i s als o questionabl e whethe r th e ai r lea dleve l woul drepresen t th e leve l t o whic hth e populatio n i s exposed . Consisten t

relationship s betwee n bloo dlea dlevel s an dexposur e t o lead-containin g soi l hav e bee n shown . Also , childre n expose dt o highe r con centration s o f

soi l an dhous e dus t

lea dhav e bee n show n t o hav e elevate dconcentration s o f lea do n thei r hands . Th e intermediat e link , fro melevate d han dlevel s o f

lea dt o elevate dbloo dlevels , ha s no t ye t bee n established . Quantitatively , bloo dlea d level s hav e bee n show n t o increas e 3 t o 6 percen t give n adoublin g of

th e soi l o r

dus t lea dcontent . Significan t

wate r lea dexposure s in thi s countr y hav e onl y occurre di

n place s havin g asof

t wate r sup pl y an dusin g leade dpipes . Suc hexposure s hav e bee n show n t o b e associate dwithsignifican t eleva tion s o f bloo dlead . The y hav e als o bee nlinke dt o case s o f menta l retardation . Exposur e t o leade dpain t stil l constitute s aver y seriou s proble mfo r

America n childre n in urba n set tings . Althoug hne w regulation s o f th e lea dconten t o f pain t shoul dalleviat e th e proble min ne w hous ing , th e poorl y enforce dregulatio n an dlac k o f regulatio n o f

th e pas t hav e lef

t aheav y burde no f lea dexposures . Mos t

o f th e studie s o n lea dpoison in g in childre n hav e assume dan associatio nwith leade dpaint . I t

i s ver y difficul t

in thes e studie s t o measur e th e actua l amoun t o f exposure . Ther e i s nevertheles s incontrovertibl e evidenc e tha t th e con tributio n fro mthi s sourc e i s ver y significan t fo r cer tai n segment s o f

th e population . Foo dlea dexposure s ar e though t t o b e asourc e o f asignifican t

portio n o f

bloo dlead . Precis e quantita tiv e estimate s o f

th e relationshi p betwee nfoo dan d bloo dlea dar e no t

available , however . Similarly , precis e quantitativ e estimate s ar e no t availabl e for th e relativ e contribution s o f differen t source s t o th e tota l amoun t

o f lea din th e diet . I t

i s clear , however , tha t probabl y th e larges t

proportio n o f

dietar y lea d i s derive dfro mfoo dprocessin g (e.g. , fro msolde r in th e seam s o f

cans) , an dsom e i s als o derive dfro m lea dinth e ai r

an dth e soil . 1.4 ASSESSMEN T O F RIS KFRO M HUMA N EXPOSUR E T O LEA D O f th e estimate d160,00 0 metri c ton s o f lea demit te dint o th e atmospher e in 1975 , th e combustio n o f gasolin e additive s an dwast e oi l accounte dfo r 9 5 percen t o f th e total . Onc e lea di s introduce dint o th e air , it i s subjec t

t o avariet y o f

processes , includin g dr y deposition , precipitation , an dresuspension . Othe r use s of lea dresul t

in othe r avenue s o f

ex posure : (1 ) Lea din pain t make s lea davailabl e b y in gestion ; (2 ) lea din plumbin g fo r potabl e wate r wher e th e wate r

i s sof t (lo w pH ) permit s leachin g an dmake s lea davailabl e b y ingestion ; (3 ) lea din th e diet , introduce db y processing , packaging , an d ra w foo dstock , als o make s lea davailabl e b y in gestion . I t

i s therefor e importan t t o realiz e tha t huma n exposur e t o lea di s th e summatio no f al l thes e comple x an dindividua l sources . Th e factor s tha t

gover nth e quantitativ e aspect s o f inhalatio n an dingestio n o f lea dhav e bee npointe d out , an dattentio n ha s bee ngive nt o th e fac t tha t in gestio n include s bot hfoo dan dnonfoo dmaterials . In th e cas e o f

children , th e nonfoo dmateria l ha s especiall y importan t

implications . Thu s th e tota l in terna l dos e i s afunctio n o f al l externa l source s with whic hth e bod y come s int o contact . Th e relativ e sig nificanc e o f

an y give n exposur e sourc e depend s o n th e specifi c exposur e circumstance s an dcertai n at tribute s o f

th e populatio na t

risk . 1.4. 1 Us e o f

Bloo d Lea d Level s i n Ris kAssess men t Th e evidenc e fo r

increase dbloo dlea dlevels , th e usua l accepte dindicato r o f lea dexposure , ha s evolve dfro mstudie s o f bot hsingle-sourc e an d multiple-sourc e exposures . Studie s o f singl e source s o f ai r lea dhav e include dbot hepidemiologica l an d clinica l investigations . Clinica l dat auniforml y demonstrat e an dquantif y th e actua l transfe r

o f lea d inai r t o blood . Th e epidemiologica l dat aar e no t a s definitive , bu t

the y ar e mor e relevan t t o th e rea l worl dan dclearl y suppor t suc harelationship . Studie s concerne dwit hdus t an dsoi l lea dex posure s ma y b e considere djointly , sinc e mos t studie s hav e no t

attempte dt o isolat e thei r relativ e contributions . Stron g evidenc e exist s t o sho w tha t thes e source s ca n b e significan t determinant s o f bloo dlea dlevels . Furthermore , investigation s in volvin g childre n expose dt o lead-contaminate ddus t hav e demonstrate dlea do nth e children' s hands . 1-1 1P.3 8

providin g stron g inferentia l evidenc e fo r a nora l rout e o f entry . Lead-base dpain t

i s associate dwithover t clinica l intoxicatio n an dwidesprea dexces s absorptio n in children . Screenin g program s in al l majo r urba n area s hav e sough t

t o abat e thi s sever e publi c healt h problem , bu t

onl y withlimite dsuccess . Thes e childre n represen t

aparticularl y hig hris k grou p withrespec t

t o th e incrementa l lea dexposur e attri butabl e t o direc t

inhalatio n o f

atmospheri c lea da s wel l a s wit hrespec t

t o th e ingestio n o f

dus t con taminate db y lea dfro mth e atmosphere . Studie s centere daroun dprimar y lea dsmelter s an dsecondar y industria l source s in urba n setting s hav e consistentl y an dindependentl y demonstrate da relationshi p betwee n bloo dlea dlevel s an dthes e mixe dsources . Mos t

characteristic s tha t

mediat e th e relationshi p betwee n bloo dlea dleve l an dlea dex posur e hav e bee n examine din severa l studies . Ag e i s certainl y asignifican t

facto r in determinin g bloo d lea dlevels , particularl y in childre n unde r 6 year s o f age . Wit hregar dt o se x differences , ther e appea r t o b e non e amon g children , wherea s in adults , male s generall y exhibi t

highe r level s tha n females . Thoug h on e stud y ha s reporte dtha t blac k childre n hav e highe r lea dlevel s tha n whit e children , th e overal l dat aar e to o spars e t o establis haconclusiv e relation ship . Socioeconomi c variable s suc ha s incom e an d education , a s wel l a s genera l healt hstatus , hav e no t bee n examine din thes e studies . A numbe r

o f summar y statement s may b e mad e abou t th e quantitativ e relationship s pertainin g t o bloo dlead . Th e weigh t o f evidenc e indicate s tha t bloo dlea dlevel s follo w alog-norma l distributio n withageometri c standar ddeviatio n o f abou t 1. 3 t o 1.5 . Th e log-norma l distributio n possesse s prop ertie s tha t

mak e it o f valu e in arrivin g at

acceptabl e maxima l exposures , sinc e i t make s it possibl e t o esti mat e aproportio n o f

apopulatio n whos e bloo dlea d level s excee dan y specifie dlevel . Th e increas e in bloo dlea dleve l resultin g fro man increas e in ai r

lea dconcentratio n i s no t constan t in magnitud e ove r

th e rang e o f

ai r lea dlevel s com monl y foun din th e environment . Th e relationshi p i s dependen t

o n man y factors , includin g rat e o f curren t exposur e an dth e histor y o f pas t exposure . Th e ob serve dratio s var y fro mai r lea dleve l t o ai r

lea d level ; the y ar e generall y betwee n 1 an d2 . Evidenc e suggest s tha t

th e ratio s fo r

childre n may b e highe r tha n thos e o f

adults ; als o it

suggest s tha t

ratio s fo r male s ma y b e highe r

tha n thos e fo r

females . Ther e i s genera l agreemen t tha t bloo dlea dlevel s begi n t o increas e whe n soi l level s ar e 50 0 t o 100 0 ppm . Mea n percen t increase s inbloo dlea dlevels , give n atwofol dincreas e insoi l lea dlevels , range d fro m3 t o 6 ; thi s i s remarkabl y consisten t give nth e divergenc e o f

th e population s studied . On e o f th e mos t

importan t

aspect s o f

ris k assess men t i s th e evaluatio nof

effect s o f

long-term , low level , o r intermitten t

exposures . I n suc hcircum stances , bloo dlea dlevel s d o no t alway s correlat e wel l withth e exposur e history . I n on e clinica l stud y o f lea dexposur e b y inhalation , a n averag e ai r leve l o f 3. 2 /xg/m 3 ove r

aperio do f

abou t 7 week s wa s re late dt o asignifican t

ris e inbloo dlea dafte r abou t 7 weeks . Whe n expose dt o clea n air , th e bloo dlea d level s o f thes e sam e subject s returne dt o pre-ex posur e levels . 1.4. 2 Us e o f

Biologica l an d Advers e Healt h Effect s o f

Lea d i n Ris kAssessmen t Lea di s no t

conclusivel y know n t o hav e an y biologica l effec t

o nma ntha t

ca n b e considere d beneficial . Therefore , an y o f th e biologica l an dad vers e healt heffect s o n ma nat thi s tim e mus t

b e con sidere dfro mamedica l poin t o f vie w tha t acknowledge s th e absenc e o f an y healt h benefit/healt hcos t

ratio . Earlie r discussio n considere dth e biologica l an d advers e healt heffect s o f lea dacros s th e entir e rang e o f lea dexposures . I nris k assessment , th e primar y focu s i s o n thos e biologica l an dadvers e physiologi ca l effect s tha t

relat e t o th e genera l population . Thoug hth e literatur e dealin g withth e healt h effect s o f lea dembrace s virtuall y al l o f th e majo r orga n system s in man , hematologica l an dneurologi ca l effect s ar e o f

prim e concern . Thes e effect s ar e summarize din Tabl e 1-1 . I t shoul db e pointe dou t tha t Tabl e 1- 1 i s alowest-observed-effect s leve l tabulation ; i.e. , it

list s th e lowes t

bloo dlea dlevel s at whic hparticula r

effect s hav e bee ncredibl y reporte d fo r give nsubpopulations . Fou r hematologica l effect s ar e considered : anemia , inhibitio no f th e enzym e 8-ALAD , urinar y 8-AL A excretion , an delevatio n o f fre e erythrocyt e porphyri n (FEP) . Anemi ai s foun din childre n wit han dwithou t con comitan t iro n deficiency . Increase dlea dintak e prompt s amor e sever e anemia . Thi s i s o f specia l im portanc e inchildre n1 t o 6 year s ol do f lowe r socio economi c status , sinc e thi s grou p als o ha s ahig hinci denc e o f iro n deficiency . Th e literatur e relatin g bloo dlea dlevel s t o a statisticall y significan t

reductio nin hemoglobi n point s t o athreshol dleve l o f 4 0 /xg/d l fo r

childre n an dacorrespondin g valu e o f 5 0 /Ag/d

l fo r adults . Th e questio n o f

alow-threshol do r

no-threshol d 1-1 2TABL E 1-1 . BLOO D LEA D LEVEL S VERSU S LOWEST OBSERVED-EFFECT S LEVEL S Lowes t level lo robserve d effects , tig Pb/d l whol e bloo d 1 0 1 5 t o 2 0 2 0 t o 2 5 4 0 4 0 4 0 5 0 5 0 t o 6 0 5 0 t o 6 0 8 0 t o 10 0 10 0 t o 12 0 Observe d effec t ALA D inhibitio n Fre e erythrocyt e porphyri n elevatio n Fre e erythrocyt e porphyri n elevatio n Increase d urinar y AL Aexcretio n Anemi a Coproporphyri n elevatio n Anemi a Cognitiv e (CNS ) deficit s Periphera l neuropathie s Encephalopath y symptom s Encephalopath y symptom s Populatio n grou p Childre n an d adult s Adul t female s an d childre n Adul t male s Childre n an d adult s Childre n Adult s an d childre n Adult s Childre n Adult s an d childre n Childre n Adult s leve l fo r th e inhibitor y effec t

o f lea do n th e enzym e 8-ALA D i s overshadowe db y th e large r issu e o f th e healt hsignificanc e o f

thi s observation . I nan y event , avalu e o f

1 0 /xg/d l bloo dlea dappear s t o represen t a threshol dlevel . Elevatio n o f urinar y 8-AL A levels , however , appear s t o b e considere da ninde x o f physiologica l impairment , an dth e threshol dleve l o f thi s effec t

i s approximatel y tha t fo r anemi ai

n childre n (i.e. , 4 0 /xg/dl) . Thi s valu e seem s t o appl y fo r bot hchildre n an dadults . Elevatio n o f

erythrocyt e porphyri n i s bette r ac cepte das.a n indicato r

o f physiologica l impairment . O n th e basi s o f

anumbe r

o f studies , threshol dvalue s of bloo dlea da t

whic herythrocyt e protoporphyri ni s elevate dappea r

t o b e 1 5 t o 2 0 /xg/d l fo r childre n an dadul t

female s an d2 0 t o 2 5 /xg/d l fo r adul t males . Th e hematologica l effect s describe dabov e ar e th e earlies t physiologica l impairment s encountere da s a functio n o f

increasin g lea dexposure s a s indexe db y bloo dlea delevations ; a s such , thos e effect s ma y b e considere dt o represen t critica l effect s o f

lea dex posure . Althoug hi t

ma y b e argue dtha t

certai n o f

th e initia l hematologica l effect s (suc ha s ALA D inhibi tion ) constitut e relativel y mild , nondebilitatin g symptom s a t

lo w bloo dlea dlevels , the y nevertheles s signa l th e onse t

o f steadil y intensifyin g advers e effect s a s bloo dlea delevation s increase . Eventually , th e hematologica l effect s reac hsuc hmagnitud e tha t the y ar e o f

clear-cu t

medica l significanc e a s indica tor s o f undu e lea dexposure . O f eve n greate r

concer n tha n earl y symptom s o f lea dexposure s (i.e. , hematologica l impairments ) ar e th e neurologi c effect s o f lea dtha t

begi n t o b e en countere da s th e hematologica l deficit s reac hclini ca l magnitudes . Childre nar e mos t clearl y th e populatio na t

ris k fo r neurologi c effects . Th e neurologi c effects , includin g bot hperiphera l neuro pathie s an dsign s o f

CN S damage , ar e firs t encoun tere dfo r som e childre na s bloo dlea dlevel s reac h5 0 t o 6 0 /xg/dl ; an dthe y ver y rapidl y intensif y in severit y a s afunctio no f increasin g bloo dlea deleva tions . O f grea t medica l concer ni s th e ver y stee p up war dris e i n th e ris k fo r permanent , sever e neurologica l damag e o r deat ha s bloo dlea deleva tion s approac han dexcee d8 0 t o 10 0 /xg/d l in children . Inne r

cit y childre n ar e o f

particula r

con cer nwithrespec t

t o th e manifestatio no f lead-in duce dneurologi c deficits , a s documente db y th e evi denc e discusse din Sectio n11.5 . Som e evidenc e ha s recentl y bee n advance dtha t suggest s tha t

long-ter mneurobehaviora l deficit s may als o b e induce db y in utero exposure s o f huma n fetuses t o lead , a s indicate db y th e apparen t highe r incidenc e o f

postnata l menta l retardatio n amon g childre n bor n o f

mother s experiencin g elevate dlea d exposur e befor e o r

durin g pregnancy . Thu s wome n o f childbearin g ag e ma y b e anothe r grou p a t

specia l ris k b y virtu e o f

th e potentia l in utero exposure s o f fetuses . However , th e paucit y o f informatio n o n ex ac t exposure s experience db y thes e mother s an dth e lac k o f othe r confirmator y studie s d o no t allo w firm statement s t o b e mad e abou t probabl e threshol d lea dexposur e level s fo r pregnan t

wome ntha t

ma y induc e late r

neurobehaviora l deficit s i n thei r children . I t i s eve n mor e difficul t

t o spea k

o f risk-to-healt h assessmen t

i nterm s o f

threshol dlevel s fo r

effect s o f lea do n reproduction , sinc e th e relevan t dat aar e sparse . However , in n o othe r aspec t o f healt heffect s i s th e potentia l fo r

deleteriou s healt heffect s o f lea d a s inherentl y grea t

a s inth e are ao f

reproductio n an d development . I n particular , lea dcrosse s th e placen ta l barrier , placin g th e huma nfetu s a t direc t risk . An dsuc hexposur e begin s at astag e o f

gestatio n whe nneura l embryoni c developmen t i s beginning . Placenta l transfer , couple dwithth e fac t tha t a n effectiv e blood-brai n barrie r i s no t presen t in huma n fetus , mean s tha t

ther e i s effectivel y adirec t pat h fro mmaterna l lea dexposur e t o th e feta l nervou s system . Availabl e informatio n suggest s tha t ther e ar e severa l possibl e consequence s t o th e newbor n arisin g fro mlea dexposure . Prematur e birt hi s suggeste da s 1-1 3P.4 0

bein g associate dwithelevate dbloo dlea dlevel s in women , an dsom e impairmen t in th e hem e biosyn theti c pathwa y ma y exis t in th e newbor n childre no f mother s havin g elevate dbloo dlea dlevels . Muc ho f th e discussio n abov e ha s deal t wit h relationship s betwee n bloo dlea dlevel s an dvariou s biologica l effect s of

lead . Thi s discussio n wa s pri maril y concerne dwit hthreshol dlevel s a t whic h healt heffect s o f

lea dar e firs t

observe din differen t populatio n groups . O f

additiona l interes t

i s th e pro portio n o f

apopulatio n exhibitin g ahealt heffec t at a give n bloo dlea dleve l (i.e. , th e dose-respons e curve) . Thre e differen t

assessment s o f

dose-respons e relationship s fo r

hematologica l effect s hav e bee n carrie dou t

an dpublished . Thes e effect s ar e th e in hibitio n o f

ALAD , elevatio n o f

ALA-U , an deleva tio n o f E Plevel s in th e blood . A s note delsewher e in thi s summary , som e questio n exist s concernin g th e relevanc e o f

ALA D inhibitio n t o huma n health . Th e othe r tw o hematologica l effect s ar e relevant . Tabl e 1-2 show s ALA- U dat afro mtw o studies , on e pub lishe dan don e don e b y EP A (se e Chapte r 13) . TABL E 1-2 . ESTIMATE D PERCENTAG E O F SUBJECT S WIT H ALA- U EXCEEDIN G 5 mg/lrt« r FO R VARIOU S BLOO D LEA D LEVEL S Bloo d lea d level , pg/d l 1 0 2 0 3 0 4 0 5 0 6 0 70 Zielhui s estimate . % 0 0 6 2 4 4 8 7 6 9 6 Aza r e t al . estimate . % 2 6 1 6 3 1 5 0 6 9 8 4 Publishe dstudie s (se e Chapte r 13 ) o f dose-respons e relationship s als o exis t fo r erythrocyt e proto porphyri n an dar e presente di n Tabl e 1-3 . TABL E 1-3 . ESTIMATE D PERCENTAG E O F CHILDRE N WIT H E P EXCEEDIN G SPECIFIE D CUTOF F POINT S FO R VARIOU S

BLOO D LEA D LEVEL S Bloo d lea d level . /ig/d l 1 0 2 0 3 0 4 0 5 0 6 0 70 8 0 Zielhui s

estimate. 8 % 0 6 2 2 37 49 ~

-

- Roel s et al .

estimate, 1 5 % 3 2 7 7 3 100

- —

-

- Piomell i

estimate, 0 % 9 1 1 4 8 8 0

-

-

-

- E P >E P o

f childre n wit h bloo d lea d level s <2 0 pg/dl . b E P >82(ifl/<l l cells . C E P >33MS/<1I 1.4. 3 Population s a tRis k Th e concep t

o f "specia l risk " i s define da s a populatio n segmen t

exhibitin g characteristic s asso ciate dsignificantl y highe r probabilit y o f

developin g acondition , illness , o r othe r abnorma l statu s a s a resul t o f exposur e t o agive ntoxi c agent . Wit h respec t t o lead , tw o suc hsegment s o f huma n popula tion s ar e currentl y definable : preschoo l childre n an d unbor nfetuses , withpregnan t wome na s th e recip ien t populatio no f

concern . 1.4.3. 1 PRESCHOO LCHILDRE N Ther e i s a nimpressiv e bod y o f dat atha t

indicate s tha t childre nar e inherentl y mor e susceptibl e t o lea d b y virtu e of

physiolog y an dtha t

the y hav e adifferen t relationshi p t o exposur e sources . Thes e physiologi ca l factor s include : (1 ) greate r lea dintak e o naper unit-body-weigh t

basis ; (2 ) greate r

net respirator y intak e a s wel l a s greate r net absorptio nan dretentio n o f lea denterin g th e gastrointestina l tract ; (3 ) rapi d growth , whic hreduce s th e margi no f safety agains t

a variet y o f

stresses , includin g nutritiona l deficiency ; (4 ) certai n incompletel y develope ddefens e mechan ism s inver y youn g children , suc ha s th e blood-brai n barrie r innewborns ; an d(5 ) differen t partitionin g of lea din th e bone s of

childre ncompare dt o tha t o f adults , wit honl y 6 0 t o 6 5 percen t o f th e lea dbod y burde noccurrin g i

nbone , an dtha t

fractio n proba bl y bein g mor e labil e tha ninadults . A nimportan t

aspec t o f th e dietar y habit s o f

ver y youn g childre nin connectio n wit hlea dexposur e i s thei r norma l mouthin g activity , suc ha s thumb-suck in g o r tastin g o f

nonfoo dobjects . Suc hbehavio r pose s aris k

o f increase dcontac t

wit hdus t

an dsoi l contaminate dwit hlead . Clinica l evidenc e als o ex ist s t o indicat e childre n ar e a t specia l ris k

fo r lea d effects . Threshold s fo r anemi aan derythrocyt e protoporphyri nelevatio nar e lowe r fo r children , an danumbe r

o f neurologica l effect s appea r a t lowe r level s o f lea dinchildre ntha n inadults . 1.4.3. 2 PREGNAN T WOME N Considerabl e evidenc e indicate s tha t pregnan t wome nar e apopulatio nsegmen t a t ris k wit hrespec t t o lea dmainl y becaus e o f increase dris k

t o th e fetu s an dmaterna l complications . Lea dcrosse s th e pla centa l barrie r

an ddoe s s o at

a nearl y stag e in embryoni c development . Althoug hquantitativ e ex pression s o f

thi s ris k canno t b e stated , certainl y th e potentia l fo r

damag e exists . Pregnanc y place s aphysiologica l stres s o n a woma nin term s o f

nutritiona l state s tha t

lea dt o iro n an dcalciu mdeficiency , in consequenc e o f whic h 1-1 4P.4 1



### bon e lea dma y b e mobilize dandth e hematopoieti c syste mma y be place da

t higher ris k t o lea dex posure . I n addition , dat asugges t

that elevate dbloo d lea dlevel s i

n pregnan t

wome n ma y resul t i n in crease dincidenc e o

f prematur e membran e rupture , placin g th e mother

a s well as her

newbor n i n a specia l ris k category . 1.4.3. 3 UNITE D STATE S POPULATIO N I N RELATIO N T O PROBABL ELEA D EX POSURE S Wit hth e exceptio n o

f thos e livin g i

n area s wit

h primary leadsmelters , mos t population s expose dt o lea dliv e i n urban areas . Resident s o f th e centra l cit

y ar e a t th e highes t

ris k i n thes e urban areas . There fore , fo r othe r than point

stationary source s o

f lead , i t i s th e urban populatio n that i s a t risk , an di

n par ticular , centra l cit

y residents . Black s an dHispanic s are probabl y subject

t o greate r

exposure t o airborn e lea dbecaus e higher

proportion s o

f thes e segment s o

f th e populatio n liv e i n urban areas . I

n th e Unite d State s i n 1970 , 149 millio n person s wer e reporte dt o liv e i n urban areas , and64 millio n i n th e centra l cities . Thes e figure s includ e abou t 1 2 millio n childre n unde r

5 year s o f age , wit happroximatel y 5 millio n o f thes e childre n livin g i

n central-city areas . Ther e ar e a

n estimate d600,00 0 childre n i n th e Unite dState s wit

hbloo dleadvalue s greate r than 4 0 /xg/dl . Thes e value s d o not resul t fro mexposure t o airborn e lea

dalone ; they als o includ e exposure t o leade dpain t

an dleadi

n food . In vie

w o f th e narro w margi n o f safet y fro mcurrentl y observe durban bloo dleadlevels , childre n expose dt o a n additiona l increment o f leadfro mth e ai r woul db e at

great ris k fo r advers e healt

heffects . O f th e roughl y 3 millio n U.S . pregnancie s pe r year , inner-city wome

n ar e estimate dt o account fo r 500,000 . I n vie w o f availabl e data , thes e wome n and thei r unbor n childre n ar e als o a

t highrisk .

1-1 5

## 2 . INTRODUCTIO N

Accordin g t o Sectio n 10 8 of th e Clea n Ai r

Ac t o f 1970 , a s amende din Jun e 1974 , acriteri adocumen t fo r aspecifi c pollutan t

o r clas s o f pollutant s shal l

. . . accuratel y reflec t

th e lates t

scientifi c knowledg e usefu l in indicatin g th e kin d an dexten t

o f al l identifiabl e effect s o n publi c healt ho r

welfar e whic hma y b e ex pecte dfro mth e presenc e o f suc hpollu tan t in th e ambien t

air , in varyin g quan tities . Ai r qualit y criteri aar e o f

necessit y base do npre sentl y availabl e scientifi c data , whic hin tur nreflec t th e sophisticatio n o f

th e technolog y use di

n obtain in g thos e dat aa s wel l a s th e magnitud e o f th e experi menta l effort s expended . Thu s ai r qualit y criteri afo r atmospheri c pollutant s ar e ascientifi c expressio n o f curren t knowledg e an duncertainties . Specifically , ai r qualit y criteri aar e expression s o f th e scientifi c knowledg e o f

th e relationship s betwee n variou s con centrations

—average dove r asuitabl e tim e perio d—

o f pollutant s i

n th e sam e atmospher e an d thei r advers e effect s upo n publi c healt han dth e en vironment . Criteri aar e issue dt o hel p mak e deci sion s abou t

th e nee dfo r

contro l o f

apollutan t

an d abou t th e developmen t

o f ai r qualit y standard s governin g th e pollutant . Ai r qualit y criteria ar e descriptive; tha t

is , the y describ e th e effect s tha t hav e bee n observe dt o occu r a s aresul t

of externa l ex posur e a t specifi c level s o f

apollutant . I n contrast , ai r qualit y standards ar e prescriptive; tha t is , the y prescrib e wha t

apolitica l jurisdictio n ha s deter mine dt o b e th e maximu mpermissibl e exposur e fo r a give n tim e in aspecifie dgeographi c area . I n th e cas e o f

criteri afo r

pollutant s tha t

appea r in th e atmospher e onl y in th e ga s phas e (an dthu s re mai n airborne) , th e sources , levels , an deffect s of ex posur e mus t

b e considere donl y a s the y affec t th e huma n populatio n throug hinhalatio n o f o r externa l contac t withtha t

pollutant . Lead , however , i s foun din th e atmospher e pri maril y a s inorgani c particulate , wit honl y asmal l fractio n normall y occurrin g a s vapor-phas e organi c lead . Consequently , inhalatio n an dcontac t ar e bu t tw o o f th e route s b y whic hhuma n population s ma y b e expose dt o lead . Som e particulat e lea dma y re mai n suspende din th e ai r an dente r

th e huma nbod y onl y b y inhalation , bu t othe r lead-containin g parti cle s wil l b e deposite do n vegetation , surfac e waters , dust , soil , pavements , interio r an dexterio r

surface s of housin g —in fact , o n an y surfac e incontac t with th e air . Thu s criteri afo r lea dmus t

b e develope dtha t will tak e int o accoun t

al l principa l route s o f ex posur e o f

th e huma npopulation . Thi s criteri adocumen t set s fort hwha t

i s know n abou t th e effect s of

lea dcontaminatio ninth e en vironmen t

o nhuma n healt han dwelfare . Thi s re quire s tha t

th e relationshi p betwee nlevel s o f ex posur e t o lead , vi aal l route s an daverage dove r a suitabl e tim e period , an dth e biologica l response s t o thos e level s b e carefull y assessed . Assessmen t o f ex posur e mus t

tak e int o consideratio nth e tempora l an dspatia l distributio n o f lea dan dit s variou s form s inth e environment . Thi s documen t

focuse s primaril y o n lea da s foun d i nit s variou s form s in th e ambien t atmosphere ; in orde r t o asses s it s effect s o nhuma nhealth , however , th e distributio nan dbiologica l availabilit y o f lea din othe r environmenta l medi ahav e bee nconsidered . Th e rational e fo r

structurin g th e documen t wa s base dprimaril y o n th e tw o majo r question s o f

ex posur e an dresponse . Th e firs t portio no f

th e docu men t i s devote dt o lea dinth e environmen t —physi ca l an dchemica l properties ; th e monitorin g o f lea d i nvariou s media ; sources , emissions , an dconcentra tion s o f lead ; an dth e transpor t an dtransformatio n o f lea dwithi nenvironmenta l media . Th e latte r sec tio ni s devote dt o biologica l response s an deffect s o n huma n healt han decosystems . A n effort ha s bee n mad e t o limi t

th e documen t

t o ahighl y objectiv e analysi s o f

th e scientifi c dat abase . Th e scientifi c literatur e ha s bee nreviewe dthroug hMarc h1977 . Th e reference s cite dd o no t constitut e acomplet e bibliograph y bu t

the y ar e hope dt o b e sufficien t t o reflec t th e curren t

stat e o f knowledg e o n thos e issue s mos t relevan t t o th e establishmen t

o f a n ai r qualit y standar dfo r

lead . Th e statu s o f

contro l technolog y fo r lea dha s no t bee n treated . Fo r

informatio n o n th e subject , th e reade r i s referre dt o appropriat e contro l technolog y documentatio npublishe db y th e Offic e o f Ai r Qualit y Plannin g an dStandard s (OAQPS) , EPA . Th e subjec t

o f adequat e margi n o f

safety stipulate d in Sectio n 10 8 o f

th e Clea n Ai r

Ac t als o i s no t treate dhere ; thi s topi c will b e considere din dept h b y EPA' s Offic e o f

Ai r Qualit y Plannin g an dStan dard s in documentatio nprepare da s apar t o f th e proces s o f

establishin g a n ai r

qualit y standard . 2- 1

## 3 . CHEMICA L AN D PHYSICA L PROPERTIE S

3 1 ELEMENTA L LEA D Lea di s agray-whit e meta l of brigh t luste r that , becaus e o f

it s eas y isolatio n an dlo w meltin g poin t (327.4°C) , wa s amon g th e firs t o f th e metal s t o b e place di n th e servic e o f

man . Lea dwa s use da s earl y a s 200 0 B.C . by th e Phoenicians , wh o travele da s fa r a s Spai n an dEnglan dt o min e it . It s mos t abundan t or e i s galena , in whic hlea di s presen t a s th e sulfid e (PbS) , an dfro mwhic hmetalli c lea di s readil y ob taine db y roasting . Th e meta l i s soft , malleable , an d ductile ; i

t i s apoo r

electrica l conductor , an di t i s highl y imperviou s t o corrosion . Thi s uniqu e com binatio n o f

physica l propertie s ha s le dt o it s us e i n pipin g an droofing , an di n container s fo r

corrosiv e liquids . B y th e tim e o f

th e Roma n Empire , i

t wa s al read y i n wid e us e i

n aqueduct s an dpubli c wate r systems , a s wel l a s in cookin g an dstorag e utensils . Lea di s uniqu e amon g th e toxi c heav y metal s i n tha t i t i s relativel y abundan t

i n th e earth' s crust ; it s abundanc e i s estimated 1 t o b e mor e tha n 100 time s tha t o f cadmiu man dmercury , tw o othe r systemi c metalli c poisons . Th e grea t environmenta l signifi canc e o f lea di s th e resul t

bot ho f it s utilit y an do f

it s abundance ; lea di s produce din fa r large r quantitie s tha n an y othe r

toxi c heav y metal , withworl dpro ductio n exceedin g 3. 5 millio n ton s pe r year. 2 Th e propertie s o f

elementa l lea d(Pb ) ar e summarize din Tabl e 3-1 . TABL E 3-1 . PROPERTIE S O F ELEMENTA L LEA D Propert y Descriptio n Atomi cweigh t Atomi cnumbe r Oxidatio n state s Densit y Meltin g poin t Boilin g poin t Covalen t radiu s (tetrahedral ) Ioni cradi i Resistivit y 207.1 9 8 2 +2 , + 4 11.35g/cm 3 at20° C 327.4° C 1744° o C 1.4 4 A 1.2 1 A(+2) , 0.7 8 A(+4 ) 21. 9 xlO" 6 ohm/c m Ther e ar e eigh t

isotope s o f

lead : Fou r

ar e stabl e an dfou r ar e radioactive . Th e averag e abundance s o f th e stabl e isotope s an dth e deca y characteristic s o f th e radioactiv e isotope s ar e liste din Tabl e 3-2 . Th e stabl e isotopi c composition s o f naturall y occurrin g lea dore s ar e no t

identical , bu t

rathe r sho w varia tion s reflectin g geologica l evolution. 3 Ther e i s n o radioactiv e progenito r

for 2<)4 Pb . However , 206 Pb , 207 Pb , an d2tm P b ar e produce db y th e radioactiv e deca y o f

238 U , 23S U , an d232 Th , respectively . Thu s th e observe disotopi c ratio s depen do n th e U/P b an d Th/P b ratio s o f

th e sourc e fro mwhic hth e or e i s derive dan dth e ag e o f th e or e deposit . Th e 2(| oPb/ 204 P b isotopi c ratio , fo r example , varie s fro m approximatel y 16. 5 t o 21 , dependin g o nth e source. 4

TABL E 3-2 . ISOTOPE S O F LEA D Isotop e 204 R b 206p b 207 R b 208 p b 210 p b 210 p b 211 p b 211p b 212 p b 212 p b 214p b 214 R b Averag e

abundance . % 1.4 26. 3 20. 8 51. 5 — — — — — — — — Deca ymod e

Stabl e Stabl e Stabl e Stabl e Ii a Ii a Ii a ii a Energy . Me V

— — — 0.01 7 0.04 7 1.4 0.8 2 0.3 6 0.2 4 0.72 0.35 Half-lif e

Stabl e Stabl e Stabl e Stabl e 2 2 y r 2 2 y r 36. 1 mi n 36. 1 mi n 10. 6 h r 10. 6 h r. 26. 8 mi n 26. 8 mi n 

### 3. 2 GENERA L CHEMISTR Y O F LEA D Lea di s th e heavies t

elemen t i nGrou p IV B o f

th e periodi c table ; thi s i s th e grou p tha t als o contain s carbon , silicon , germanium , an dtin . Unlik e th e chemistr y o f

carbon , however , th e inorgani c chemis tr y o f lea di s dominate db y th e divalen t ( + 2 ) oxida tio nstat e rathe r

tha n th e tetravalen t

( +4 ) oxidatio n state . Thi s importan t

chemica l featur e i s adirec t resul t o f th e fac t tha t th e strength s o f

singl e bond s betwee n th e Grou p I V atom s an dothe r atom s generall y decreas e a s th e atomi c numbe r o f th e Grou p I V ato mincreases. 5 Thus , th e averag e energ y o f aC- H bon di s 10 0 kcal/mole , an di t i s thi s facto r tha t stabilize s CH 4 relativ e toCH r Fo r lead , th e Pb H energ y i s onl y approximatel y 6 5 kcal/mole , an d thi s i s to o smal l t o compensat e fo r th e Pb(II ) —

* Pb(IV ) promotiona l energy . I t i s thi s sam e feature , o f course , tha t

explain s th e marke ddifferenc e in th eP.4 4

tendencie s t o catenatio n show n b y thes e elements . Thoug hC- C bond s ar e presen t in literall y million s o f compounds , lea di s no t know n t o forman y cate nate dinorgani c compounds . A listin g o f

th e solubilitie s an dphysica l propertie s o f th e mor e commo n compound s o f lea di s give n in Appendi x B . A s ca n b e discerne dfro mthos e data , mos t inorgani c lea dsalt s ar e sparingl y solubl e (e.g. , PbF 2 , PbCl 2 ) o r

virtuall y insolubl e (PbS0 4 , PbCr0 4 ) i

n water ; th e notabl e exception s ar e lea d nitrate , Pb(N0 3 ) 2 , an dlea dacetate , Pb(OCOCH 3 ) 2 . Inorgani c lea d(II ) salt s ar e generall y relativel y high-melting-poin t

solid s withcorrespondingl y lo w vapo r pressure s at

roo mtemperatures . Th e vapo r pressure s o f

th e mos t

commonl y encountere dlea d salt s ar e als o tabulate din Appendi x B . Th e deca y o f lea dsalt s in th e atmospher e i s discusse din Sectio n 6.2.2 . 3. 3 ORGANOMETALLI C CHEMISTR Y O F LEA D Th e propertie s o f

organolea dcompound s (i.e. , compound s containin g bond s betwee n lea dan dcar bon ) ar e entirel y differen t fro mthos e o f

th e in organi c compound s o f

lead . Th e Pb- C bon denerg y i s approximatel y 130 kcal/mole, 6 o r twic e th e Pb- H valu e cite dabove . Consequently , th e organi c chemistr y o f

lea di s dominate db y th e tetravalen t ( + 4 ) oxidatio n state . An importan t propert y o f

mos t organolea dcompound s i s tha t the y underg o photo lysi s whe n expose dt o light . Th e physica l propertie s o f som e o f

th e mor e importan t

organolea dcom pound s ar e summarize din Tabl e 3-3 . TABL E 3-3 . PROPERTIE S O F MAJO R ORGANOLEA D COMPOUND S Compoun d Tetramethy l lea d Tetraethy l lea d Tetrapheny l lea d Hexamethy l lea d Hexaethy l lea d Formul a (CH 3 ) 4 P b (C 2 H 5 ) 4 P b (C 6 H 5 ) 4 P b (CH 3 ) 6 Pb 2 (C 2 H 5 ) 6 Pb 2 Appearanc e Colorles s liqui d Colorles s liqui d Whit e soli d Pal e oi l Yello woi l m.p. . C -27. 5 -13 0 22 3 3 8 3 6 b.p. . C

11 0 82 a Decompose s Decompose s 100 b A t 1 3 m m pressure . A t 2 m m pressure . Becaus e o f

thei r us e a s antiknoc k

agent s in gasolin e an dothe r

fuels , th e mos t

importan t organolea dcompound s ar e th e tetraalky l com pound s tetraethy l lea d(TEL ) an dtetramethy l lea d (TML) . A s woul db e expecte dfo r suc hnonpola r compounds , TE Lan dTM Lar e insolubl e in wate r bu t solubl e in hydrocarbo n solvent s (e.g. , gasoline) . Thes e tw o compound s ar e manufacture dinex tremel y larg e quantitie s (Chapte r 5) b y th e reactio n o f th e alky l chlorid e withlead-sodiu malloy: 7 4NaP b + 4C 2 H,C 1 —(C 2 H 5 ) 4 P b + 3P b + 4NaC I Th e methy l compound , TML , i s als o manufacture d b y aGrignar dproces s involvin g th e electrolysi s o f lea dpellet s i n methylmagnesiu mchloride: 7 2CHJvlgC I + 2CH 3 C 1 (CH 3 ) 4 P b + + P b 2MgCl 2 Thes e lea dcompound s ar e remove dfro maut o o r othe r interna l combustio n engine s b y aproces s calle dlea dscavenging , in whic hthe y reac t inth e combustio n chambe r

withhalogenate dhydrocarbo n additive s (notabl y ethylen e dibromid e an dethylen e dichloride ) t o formlea dhalides , usuall y bro mochlorolead . Suc hinorgani c compound s ap parentl y originat e a s vapor s in th e combustio n chambe r o f a n automobil e engine . Durin g thei r passag e throug hth e exhaus t system , however , the y condens e t o formsmal l spherica l particle s with diameter s o nth e orde r o f afew tenth s o f

a micrometer ; the y als o condens e o r absor b ont o th e surface s o f

co-entraine dparticle s derive dfro mth e intak e ai r

o r fro mcorrosio no f

th e exhaus t

system . Consequently , lea dhalide s emitte dfro mautomobil e exhaus t ar e presen t

a s vapors , a s pur e soli dparticles , an da s acoatin g o nth e surfac e o f particulat e sub strates . Mobil e sourc e emission s ar e discusse din detai l inChapte r

6 (Sectio n6.2.2.1) . Severa l hundre dothe r organolea dcompound s hav e bee nsynthesized , an dth e propertie s o f man y o f the mar e reporte db y Shapir o an dFrey. 7 Som e o f thes e ar e use din th e commercia l preparatio n o f organomercur y compound s use da s fungicides , an d thei r us e a s catalyst s an dstabilizer s in industria l processe s ha s bee n investigate dextensively . 3 4 COMPLE X FORMATIO N AN D CHELA TIO N Th e bondin g in organometalli c derivative s o f lea d i s principall y covalen t

rathe r tha n ioni c becaus e o f th e smal l differenc e in th e electronegativitie s o f lea d (1.8 ) an dcarbo n(2.6) . A s i s th e cas e invirtuall y al l meta l complexes , however , th e bondin g i s o f th e donor-accepto r

type , in whic hbot helectron s in th e bondin g orbita l originat e fro mth e carbo n atom . Th e dono r

atom s inameta l comple x could , o f 3- 2course , b e almos t an y basi c ato mo r

molecule ; th e onl y requiremen t

i s tha t adonor , usuall y calle da ligand , mus t

hav e apai r

o f electron s availabl e fo r bon dformation . I n general , th e meta l ato moccupie s acentra l positio n in th e complex , a s exemplifie db y th e lea dato min tetramethy l lea d(a) , whic hi s

H 3 C # CH ,

H, C CH ,

(a ) tetrahedrall y surrounde db y fou r methy l groups . I n thes e simpl e organolea dcompounds , th e lea di s usuall y presen t

a s Pb(IV) , an dth e complexe s ar e relativel y inert . Thes e simpl e ligands , whic hbin dt o meta l at onl y asingl e site , ar e calle dmonodentat e ligands . Som e ligands , however , ca n bin dt o th e meta l ato mb y mor e tha n on e dono r atom , s o a s t o formaheterocycli c rin g structure . Ring s o f thi s genera l typ e ar e calle dchelat e rings , an dth e dono r molecule s whic hfor

mthe mar e calle dpolydentat e (a s oppose dt o monodendate ) ligand s o r chelatin g agents . I n th e chemistr y of lead , chelatio n normall y involve s Pb(ll) , leadin g t o kineticall y quit e labil e (althoug hhighl y stable ) complexe s tha t ar e usuall y six-coordinate . A Wid

e variet y o f

biologicall y sig nifican t chelate s withligands , suc ha s amin o acids , peptides , nucleotides , an dsimila r macromolecules , ar e known . Th e simples t structur e o f

thi s typ e i s with th e amin o acid , glycine , a s represente din (b ) fo r a 1: 2 (metal : ligand ) complex . H 2 0 O O . CH . / P b NH „ .NH . \ \ CH ,



### I • C O H 2 0 Th e importanc e o f chelatin g agent s in th e presen t contex t i s thei r widesprea dus e in th e treatmen t o f lea dan dothe r

meta l poisoning . Sinc e Pb(II ) i s arelativel y sof t (o r clas s b ) meta l ion, 8 it form s stron g bond s t o sof t dono r atom s lik e th e sulfu r

atom s in th e cystein e residue s o f protein s an denzymes ; i

t als o coordinate s strongl y wit hth e imidazol e group s o f

histidin e residue s an dwit hth e carboxy l group s o f

glutami c an dasparti c aci d residues . I nlivin g systems , therefore , lea datom s bin dt o thes e peptid e residue s i nproteins , thereb y preventin g th e protein s fro mcarryin g ou t thei r func tion s b y changin g th e tertiar y structur e o f th e protei n o r b y blockin g th e approac hb y asubstrat e t o th e ac tiv e sit e o f

th e protein . Th e rol e o f th e chelatin g agent s i s t o compet e withth e peptide s fo r th e meta l b y formin g stabl e chelat e complexe s tha t ca n the n b e transporte dfro mth e protei nan deventuall y ex crete db y th e body . Fo r simpl e thermodynami c reason s (se e Appendi x B) , chelat e complexe s ar e muc hmor e stabl e tha nmonodentat e meta l complex es , an dit

i s thi s enhance dstabilit y tha t i s th e basi s for thei r abilit y t o compet e favorabl y withprotein s an dothe r

ligand s fo r

th e meta l ions . Th e chelatin g agent s mos t

commonl y use dfo r

th e treatmen t

o f

<s > O I O-C-CH . O I<x> CH 2 -C O N-CH 2 -CH 2 - N / 

### /

J 

### \ O-C-CH . O CH 2 -C O . O EDT A (c ) CH . H S —C C H c ; CH 3 NH 2 PENICILLAMIN E O O H (b ) (d ) 3- 3P.4 6

lea dpoisonin g ar e ethylenediaminetetraacetat e ion s (EDTA ) (c) , D-penicillamin e (d) , an dthei r deriva tives . EDT A i s know n t o ac t a s ahexadentat e ligan d towar dmetals. 9 Recen t X-ra y diffractio n studie s hav e demonstrate dtha t D-penicillamin e i s atriden tat e ligan d(bindin g throug hS , N , an dO ) towar d cobalt, 1 0 chromium, " an dlead, 1 2 bu t monodentat e towar dmercury. 131 5 I t shoul db e note dtha t

bot hth e stoichiometr y an d structure s o f

meta l chelat e depen do n pH , an dtha t differen t structure s may occu r

in crystal s fro mthos e manifes t in solution . I t

will suffic e t o state , however , tha t severa l ligand s ca n b e foun dtha t ar e capabl e o f sufficientl y stron g chelatio n withlea dpresen t in th e bod y unde r

physiologica l condition s t o enabl e thei r us e in th e effectiv e treatmen t o f lea dpoisoning . 3. 5 REFERENCE S FO RCHAPTE R3 1 . Moeller , T . Inorgani c Chemistry . Joh n Wile y an dSons , Inc. , Ne w York . 1953 . 96 6 p . 2 . Dyrssen , D . Th e changin g chemistr y o f th e oceans . Ambio . /(l):21-25 , 1972 . 3 . Russell , R . an dR . Farquhar . Lea dIsotope s i n Geology , lnterscience . Ne w York . I960 . 4 . Doe , B . Lea dIsotopes . Springer-Verlag , Ne w York . 1970 . p . 3-80 . 5 . Cotton , F . A . an dG . Wilkinson . Advance dInorgani c Chemistry . Joh n Wile y an dSons , Inc. , Ne w York . 1972 . 6 . Shaw , C . F. . Ill , an dA . L . Allred . Nonbonde dinteraction s i n organometalli c compound s o f Grou p I V B . Organometalli c Chem . Rev . A 30:95 , 1970 . 7 . Shapiro , H . an dF . W . Frey . Th e Organi c Compound s o f Lead , lnterscienc e Publishers , Joh n Wile y an dSons , Inc. , Ne w York , 1968,48 6 p . 8 . Basolo , F . an dR . G . Pearson . Mechanism s o f Inorgani c Reactions . J . Wile y an dSons , Inc. , Ne w York . 1967 . p . 23-25 , 113-119 . 9 . Richards , S. , B . Pedersen , J . Silverton , an dJ . L . Hoard . Stereochemistr y o f

ethylenediaminetetraacetat e complex es . Inorg . Chem . 5:27-33 , Jan . 1964 . 10 . d e Meester . P . an dD . J . Hodgson . Mode l fo r th e bindin g o f D-penicillamin e t o meta l ion s i n livin g systems : Syn thesi s an dstructur e o f L-histidinyl-D-penicil laminatocobal t

(III ) monohydrate . [CO(L-his ) (D pen)]H 2 0 . J . Am . Chem . Soc . 99( 1 ):10l-104 . 1977 . 11 . d e Meester , P . an dD . J . Hodgson . Synthesi s an dX-ra y structur e o f

L-histidinyl-D-penicillaminatocobal t (III ) an dL-histidinyl-D-penicillaminatochromiu m(111) . J . Chem . Soc . Chem . Commun . 280 , 1976 . 12 . Freeman , H . C , G . N . Stevens , an d1 . F . Taylor , Jr . Meta l bindin g i

n chelatio n therapy : Th e crysta l structur e o f D penicillaminatolea d(II) . J . Chem . Soc . Chem . Commun . / 0:366-367 , 1974 . I 3 . Wong . Y . S. . P . C . Chieh , an dA . J . Carty . Th e interactio n o f organomercur y pollutant s withbiologicall y importan t sites . Can . J . Chem . 5/:2597 , 1973 . 14 . Wong , Y . S. , P . C . Chieh , an dA . J . Carty . Bindin g o f methylmercur y b y amino-acids : X-ra y structur e o f D , L penicillaminatomethylmercur y (II) . J . Chem . Soc . Chem . Commun . 741 , 1973 . 15 . Carty , A . J . an dN.J . Taylor . Bindin g o f inorgani c mercur y at biologica l sites . J . Chem . Soc . Chem . Commun . 214 . 1976 .

3-4

## 4 . SAMPLIN G AN D ANALYTICA L METHOD S FO RLEA D

4 1 INTRODUCTIO N Monitorin g fo r

lea din th e environment , whic hin clude s samplin g an dmeasurement , i s ademandin g tas k tha t require s carefu l attention . Lea di s receivin g carefu l scrutin y a s apollutant , an dth e accurat e assessmen t

o f it s impac t

o n th e environmen t

i s con tingen t o n th e acquisitio n o f

vali dmonitorin g data . Furthermore , th e movemen t an daccumulatio no f lea din ecosystem s occu r vi acomple x pathway s an d compartments . I n addition , man y difficultie s ar e in heren t in th e identificatio n an dtracin g of lea din it s variou s form s in th e environment . Airborn e lea d originate s fro mmanmad e sources , primaril y th e automobile , an di s extracte dfro mth e atmospher e b y animals , vegetation , soil , an dwater . Knowledg e o f th e concentration s o f

lea di n thes e variou s medi a an dth e movemen t

o f lea dbetwee n an damon g the m i s critica l fo r

controllin g lea dpollutio nan dfo r mitigatin g th e advers e effect s o f lea di n th e environ men t o n people . Samplin g an danalytica l method s for monitorin g lea dhav e bee n devise dfo r almos t ever y purpose . Som e method s ar e to o tediou s o r expensiv e fo r genera l use ; other s ar e relativel y easil y applie dbu t produc e result s o f

limite dutilit y o r

questionabl e validity ; an dother s ar e appropriat e fo r us e i n monitorin g lea din certai n system s bu t no t i nothers . Th e monitorin g o f

environmenta l lea dca nb e car rie dou t withalmos t

an y precisio n deeme dnecess ary , bu t actuall y obtainin g precis e an daccurat e result s i s no t

atrivia l tas k

in man y instances . (Se e Chapte r 9 fo r adiscussio n o f

th e difficultie s in reproducin g bloo dlea danalyses. ) Th e primar y proble mi s tha t

o f determinin g wha t

type s o f monitorin g procedure s ar e necessar y t o realiz e societa l objective s fo r

protectin g huma n healt ho na practica l basis . Th e objectiv e o f thi s chapte r

i s t o revie w th e statu s o f

th e monitorin g procedure s avail able . Anothe r

seriou s proble mi s th e presen t lac k of instrumentatio n fo r

th e continuou s analysi s o f aero sol . Monitorin g fo r

lea dinvolve s a n operationa l se quence , base do n th e scientifi c method , a s show n schematicall y in Figur e 4-1 . Th e typ e o f dat at o b e collecte dmus t

b e define dclearl y o nth e basi s o f th e question(s ) t o b e answered . Th e require daccurac y o f th e dat amus t

b e determine dan dassure db y mean s o f aqualit y assuranc e strateg y fo r al l aspect s o f

th e monitorin g operation . Similarly , th e samplin g strateg y mus t

b e base do nth e typ e o f dat aneede d an dye t tak e int o accoun t

requirement s impose db y th e analytica l method s t o b e used . Th e selectio n an d applicatio no f

th e analytica l method s ar e in tur n in fluencedb y th e kin do f dat aneeded , th e type s o f sample s collected , th e analytica l capabilitie s availa ble , an dothe r

factors . Ultimately , analysi s o f th e dat aobtaine ddetermine s whethe r th e sequenc e ha s reache dasatisfactor y conclusio no r if modification s o f an y particula r

segment s o f

th e sequenc e ar e re quired . Althoug hther e ar e numerou s technica l source s o f

informatio n concernin g samplin g strategy , samplin g methods , sampl e preparation , an danalyses , onl y afe

w o f th e mos t noteworth y ar e cite dhere . Thes e includ e th e Nationa l Academ y o f Science s repor t

o nlead, 1 Stern' s three-volum e com pendiu mo n ai r

pollution, 2 th e Geologica l Surve y revie w o f lea dinth e environment, 3 an dth e Nationa l Scienc e Foundatio npublication , "Monitorin g fo r Lea di n th e Environment." 4 I n succeedin g sections , th e specifi c operation s in volve dinmonitorin g ar e discussed . Sit e selectio n i s treate dsuccinctl y becaus e o f th e deart ho f

criteri ain th e literatur e an dth e necessit y fo r establishin g specifi c sit e criteri afo r

eac hsamplin g requirement . Muc hremain s t o b e don e towar destablishin g cri teri afo r locatio no f

samplers . Th e variou s sampler s use dt o collec t

lea ddat aar e described . Method s fo r collectin g dustfall , water , soil , an dvegetatio n sam ple s ar e reviewe dalon g withcurren t samplin g method s specifi c fo r

mobil e an dstationar y sources . Th e processin g o f

sample s fo r

analysi s i s critica l an d influence s th e selectio n o f filte r material s an d characteristics . Thi s i s an are ao f monitorin g tha t

i s receivin g muc hattentio nbecaus e o f th e inter ference s tha t

hav e bee n encountered . Th e analytica l sectio n i s length y becaus e o f th e 4- 1P.4 8

FORMULAT E HYPOTHESI S O R DELINEAT E QUESTION S T O B E ANSWERE D

DEFIN E TYP E O F DAT A NEEDE D AN D QUALIT YASSURANC E REQUIRE D

PLA N SAMPLIN G STRATEG Y SELEC T SIT E CHOOS E

COLLECTIO N METHOD S DETERMIN E SAMPL E STORAG E AN D TRANSPOR T REQUIREMENT S

OBTAI N SAMPLE S ANALYZ E SAMPLE S PREPAR E SAMPL E ! « » MEASURE I LEA D j MAK E QUALIT Y ASSURANC E CHECK S

ANALYZE/INTERPRE TDAT A HYPOTHESI S CONFIRMED ? QUESTION S ANSWERED ? N O YE S (END ) Figur e 4-1 . Sequenc e o f operation s involve d i n monitorin g fo r lea d i n th e environment . larg e variet y o f

method s applie dt o lea danalysis . Analysi s i s th e mos t

advance dare ao f

monitorin g operations , an di

f use dproperly , analytica l method s ar e alread y availabl e tha t ar e capabl e o f

providin g al l th e require ddata . 4. 2 SAMPLIN G Th e purpos e o f

samplin g i s t o obtai n lead-contain in g particles , adsorbe dgases , liquids , an dsoli dsam ple s tha t will provid e ameasur e o f th e natur e an d concentratio n o f

lea da t

variou s point s inth e environment . Samplin g encompasse s no t onl y th e metho do f

sampl e collection , bu t als o th e selectio n of samplin g site s an dprocedure s applicabl e t o th e processin g o f

samples . 4.2. 1 Sample rSit e Selectio n Th e locatio n o f

sampl e collectio n device s ha s im portan t an dpervasiv e effect s o n th e dat aobtained . I n monitorin g ambien t

ai r fo r lead , th e proximit y t o th e sample r

o f mobil e an dstationar y source s i s o f prim e importance . Als o o f importanc e ar e th e heigh t o f th e sample r

intak e abov e th e groun dan dth e loca l topography , climate , an dlea dleve l in th e soil . Ott 5 ha s enumerate dth e problem s an ddifficultie s en countere dincomparin g dat aobtaine dfro mai r monitorin g station s in differen t cities . Genera l guideline s fo r locatin g ambien t

ai r sampler s includ e th e following : 1 . Sampler s shoul db e aunifor mheigh t abov e th e ground , althoug ht o asses s th e ris k t o children , som e sampler s shoul dals o b e lo cate dat achild' s heigh t

( 2 t o 3 ft) . 2 . Sample r

inlet s shoul db e at

leas t 3 mfro m an y obstruction . 3 . Sampler s shoul db e locate di narea s fre e o f loca l sourc e influenc e an dconvectio no r edd y currents . Mos t existin g sample r

site s d o no t

mee t thes e cri teria , an dinformatio no nsample r locatio ni s no t usuall y provide dwit hdata. 5 Th e numbe r o f monitorin g site s inanai r monitorin g networ k

shoul d b e relate dt o geography , population , an dsources. 6 Sinc e ther e i s n o suitable , continuou s metho dfo r measurin g lea di

n air , th e samplin g perio dan dfre quenc y ar e als o importan t inth e overal l samplin g strategy . I t

shoul db e noted , however , tha t i t i s no t possibl e t o discus s samplin g plan s outsid e th e con tex t o f aparticula r

objectiv e (e.g. , characterizatio n o f rura l o r urba nbackgroun dlevels , assessmen t of healt hhazard s t o people , determinatio no f sourc e effects , o r

delineatio nof

transpor t

mechanisms). 4 Th e treatmen t

o f samplin g indetai l i s outsid e th e scop e o f thi s discussion , bu t

referenc e shoul db e mad e t o th e availabl e sources. 6 ' 7 4.2. 2 Samplin g Error s Th e fidelit y withwhic hasampl e reflect s th e quan tit y an dnatur e o f

lea dinan y mediu mbein g sample d i s basi c t o th e obtainin g o f vali ddat aan dtherefor e t o a n understandin g o f th e phenomen abein g in vestigated . I nSectio n 4.2.1 , th e importanc e o f sit e selectio nfo r

collectin g sample s o f

airborn e lea dwa s noted . I n Sectio n 4.2.6.2 , th e problem s o f dilutio n o f sample s fro mmobil e source s ar e noted . A genera l samplin g erro r

associate dwit hsamplin g o f airborn e particulate s i s discusse dhere . Mos t ambien t

sampl e collection s ar e obtaine d nonisokinetically ; tha t

is , a s th e ai r

i s draw nint o th e sample r inlet , th e spee dan ddirectio n o f th e ai r ar e changed . Th e inertia l characteristi c o f suspende d particulate s brin g abou t losse s o f

large r particle s bot hby drif

t fro mth e sample dai r

strea man db y im pactio n o n th e surfac e o f th e sample r

inlet . I t ha s bee n show n tha t

appreciabl e error s may resul t fro m nonisokineti c sampling , primaril y becaus e o f th e los s o f larg e particle s (thos e with diameter s exceedin g 1 0 4- 2fim). 8Generally , it i s no t possibl e t o estimat e th e er ro r unde ran y specifie dconditions . Butsuc herror s ma y b e minimize db y avoidin g edd y formation , tur bulence , divergenc e o r

convergence , an dchange s in directio n o f

th e sample dai r

stream . 4.2. 3 Samplin g fo rAirborn e Particulat e Lea d Airborn e lea di s primaril y carrie db y particulate s o r aerosols , bu t

in smalle r

concentrations , i

t may oc cu r in th e formo f

organi c gases . Sampler s rang e fro mth e widel y use dhigh-volum e filte r sample r t o a variet y o f

othe r collector s tha t

emplo y filters , im pactors , an dimpingers . 4.2.3. 1 HIGH-VOLUM ESAMPLE R Th e mos t

widel y use dmetho dfor samplin g air born e particulate s in th e 0.1 - t o ]0-fim rang e i s th e high-volum e ai r

sampler, 91 0 whic hi s routinel y use d in th e Nationa l Ai r

Surveillanc e Networks . Th e metho drequire s avacuu mcleane r typ e o f ai r blowe r tha t draw s ai r

throug hafilte r

at rate s a s hig ha s 2 m 3 /min . Sinc e th e norma l samplin g perio di s 2 4 hr , particulate s fro masampl e volum e o f abou t 200 0 m 3 ar e collected . Becaus e th e ai r flo w varie s withfilte r typ e an dth e degre e o f

filte r loading , i

t i s necessar y at leas t t o measur e initia l an dfinal ai r flows . Gros s particulat e loadin g i s determine db y carefull y weighin g th e filte r

befor e an dafte r

sampl e collec tion . Th e lea dconten t

i s the n determine db y on e o f th e analytica l method s describe din th e following . Commercia l high-volum e sampler s i n whic hth e filte r i s hel di

n ahorizonta l plan e an dprotecte d fro mdustfal l by ahousin g ar e available. 9 An 8 - by 10-in . glas s fibe r

filte r i s usuall y recommended . Problem s withfilte r

selectio n ar e discusse dinasub sequen t section . High-volum e sampler s ar e inexpensive , eas y t o operate , an din widesprea duse . A measur e o f thei r precisio n an deas e o f

operatio n can b e deduce dfro m th e observatio n tha t

an interlaborator y relativ e stan dar ddeviatio n fo r

tota l particulat e collectio nha s bee n reporte do f

3. 7 percen t

ove r th e rang e 8 0 t o 12 5 /ug/m- \Th e disadvantage s o f th e high-volum e sample r includ e th e lac k

o f separatio n o f

particu late s b y size , th e interference s by impuritie s in th e filter s withsom e analytica l procedures , an dth e par ticl e fracturin g tha t

occur s o n impact , whic h preclude s subsequen t

determinatio n o f

siz e distri bution. 9 I n addition , high-volum e sampler s ar e usuall y operate dnonisokinetically ; thi s result s ina n underestimatio n o f

th e airborn e concentratio no f larg e particles . "I f

ther e i s appreciabl e mas s inpar ticle s withaerodynami c diameter s greate r tha n abou t

1 0 fim, thi s effec t ma y b e important . Isokineti c impacto r

measurement s ru nin Lo s Angele s hav e indicate dtha t th e mas s media n equivalen t

diameter s ar e apparentl y large r tha n thos e measure dunde r

nonisokineti c conditions. 1 2 Thi s topi c i s als o discusse di n Sectio n6.3.2.1 . A ninterlaborator y compariso n progra mbein g conducte din Europ e ha s compare dtota l particulat e result s fro mhigh - an dlow-volum e samplers. 1 3 Base do n th e low-volum e sample r data , th e preci sio nof tota l particulat e collectio no f th e high volum e sample r

i s estimate dat

± 0. 5 /ug/m 3

. O f course , suc hcomparison s appl y onl y t o th e particu lar condition s an dmethodolog y o f samplin g an d analysi s use din tha t

study . 4.2.3. 2 DICHOTOMOU S SAMPLE R Th e siz e distributio n o f airborn e particulate s ca n b e determine dby usin g multistag e impactor s an d impinger s o r

b y analyzin g unfractionate dsamples . Suc hinformatio n i s desirabl e for monitorin g source s o f apollutan t

a s wel l a s fo r

assessin g potentia l effect s o f th e pollutan t

o n huma nhealth . Th e abov e technique s ar e expensiv e t o us e o nalarg e scal e an d generall y requir e extende dsamplin g periods . Measurements' 4 hav e indicate dtha t airborn e partic ulate s usuall y hav e abimoda l siz e distributio n an d als o tha t ther e i s adistinc t

differenc e inth e effect s o f smal l an dlarg e particle s o nhumans. 1 5 A dichotomou s sample r fo r particulate s ha s bee n designe dt o collec t

an dfractionat e sample s int o tw o siz e ranges. 1 6 Th e dichotomou s sample r use s virtua l impactio n t o avoi dth e particl e bounc e error s fre quentl y encountere dwithcascad e impactors. 1 7 Vir tua l impactio n involve s th e separatio n o f particle s int o separat e ai r

stream s by inertia l means. 1 6 I n th e apparatus , th e larges t

portio n o f

th e ai r strea mi s pulle dthroug ha n annula r pat hs o tha t

i t change s direction , whil e asmal l ai r flow i s maintaine dina straigh t path . Th e inerti ao f

th e large r

particulate s tend s t o kee p the minth e straigh t pat hwhil e th e smalle r particle s ar e diverte dwithth e mai n stream . Tw o stage s o f

virtua l impactio nhav e bee n use dt o obtai n bette r

fractionation . Membran e filter s in th e tw o ai r path s collec t

th e respectiv e samples . Th e particl e diamete r

demarcatio n o f

th e tw o fraction s i s normall y betwee n 2. 0 an d3. 5 fim i nvariou s designs . Commercia l dichotomou s sampler s ar e available , bu t

the y ar e considerabl y mor e expensiv e tha nhigh-volum e samplers . Test s o f aprototyp e dichotomou s sample rinSt . Loui s indicated 1 6 that8 0 percen to f th e particulat e lea dwa s containe dinparticle s les s than 2 fim i n 4- 3P.5 0

diameter , wherea s onl y 2 0 percen t wa s foun dt o b e in large r particles . Othe r

test s t o evaluat e th e perfor manc e o f dichotomou s sampler s ar e unde r way. 1 8 4.2.3. 3 TAP ESAMPLE R Thoug hdustfal l an dhigh-volum e collector s usuall y requir e 2 4 h r

samplin g period s t o obtai n a sufficien t analytica l sample , ther e ma y b e anee din sourc e an dtranspor t

studie s t o monito r

airborn e particulate s fo r

shorte r tim e intervals . Th e tap e sample r draw s ai r

throug haspo t

o n afilter

tap e tha t advance s automaticall y a t prese t interval s (e.g. , ev er y 2 hr). 9 A t

asamplin g rat e o f

abou t 0.5 6 m 3 /h r (2 0 ft 3 /hr ) fo r

a2-h r interva l an dwit ha2.54-c m ( 1 -in. ) spo t

diameter , i

t i s possibl e t o analyz e th e collecte dsampl e fo r

lea dusin g anodi c strippin g voltammetr y analysis. 1 9 Atmospheri c con centration s o f

lea drangin g fro m0. 1 t o 2. 0 /xg/m 3 wer e measure dat

monitorin g station s in Chicag o an dWashingto n usin g tap e samplers. 1 9 Diurna l cy cle s in airborn e lea dconcentration s wer e obtaine d tha t correlat e wit hmanmad e source s o f lead . 4.2.3. 4 IMPACTOR S AN D IMPINGER S Impactor s ar e multistag e particulat e collectio n device s designe dt o provid e anumbe r o f siz e frac tions . Th e modifie dAnderse n cascad e impacto r use din th e Nationa l Ai r Surveillanc e Network s (NASN ) i s describe dhere. 2 0 Other s ar e describe din standar dtexts. 2

- 2 1 Th e cascad e impacto r

fractionate s particle s ina serie s o f fiv e o r si x collectio n stages. 2 0 Particle s pas s throug haserie s o f

jets , 40 0 pe r

stage , tha t

ar e progressivel y smaller . Unde r eac hserie s o f

jet s i s a collectio n plate . Th e siz e fractio n o f particle s col lecte da t eac hstag e depend s o n th e ai r velocity , geometry , an dpreviou s stages . Th e las t stag e con sist s o f afilter . Ai r

i s pumpe dthroug hth e impacto r at 0.1 4 t o 0.1 7 m 3 /mi n b y mean s o f a n ai r pum p o n th e downstrea mside . Aluminu mfoi l i s use da s th e collector , an dth e siz e fractio n i s determine db y weighin g befor e an dafte r a24-h r

sampl e i s col lected . Fiv e fraction s ar e usuall y obtained : < 1.1, 1. 1 t o 2.0 , 2. 0 t o 3.3 , 3. 3 t o 7 , an d> 7 ^m . Result s obtaine db y th e NASN 2 2 indicat e tha t lea d particulate s typicall y hav e mas s media n diameter s in th e rang e o f

0.2 5 t o 1.4 3 fim. Analysi s b y optica l emissio n spectrograph y indicate dtha t fo r particle s les s tha n 0. 5 fim in diameter , th e lea dconten t wa s 2 t o 4 percent . A cascad e impacto r ha s als o bee n ap plie dt o multielemen t

siz e characterizatio n o f urba n aerosols. 2 3 A size-selectiv e particl e sample r usin g cyclone s ha s als o bee ndescribed, 2 4 an daten-fraction-siz e

sampl e ca n b e obtaine dwit hth e Lundgre nimpac tor. 2 5 Impinger s collec t

atmospheri c aerosol s b y im pingemen t

ont o asurfac e submerge dinaliquid. 2 9 Impactor s ar e sometime s calle ddr y impingers . A s in impactors , impingemen t relie s o n th e inertia ! characteristic s o f

th e particl e fo r

collectio n o n asur face . Hig hcollectio n efficiencie s fo r particle s a s smal l a s 0. 1 fim may b e obtaine dinwe t impingers. 2 4.2. 4 Samplin g fo rVapor-Phas e Organi cLea d Compound s I ndeterminin g th e tota l quantit y o f lea dinth e at mosphere , ai r

i s draw n throug hamembran e o r glas s filter fo r collectin g particulat e lea dan dthe n throug hasuitabl e reagen t o r absorbe r

fo r collectio n o f gaseou s compound s tha t pas s throug hth e filter. 2 6 Sinc e th e norma l filte r

use dha s anomina l 0.45-/u m por e size , analysi s b y thi s metho dwil l includ e an y materia l tha t

passe s throug hthes e pores , althoug hit i s considere dt o b e primaril y organi c lead . Organi c lea dma y b e collecte do n iodin e crystals , adsorbe d o n activate dcharcoal , o r absorbe dina n iodin e monochlorid e solution. 4 Review s o f th e procedure s ar e available. 272 8 Th e procedure s usin g iodin e monochlorid e hav e bee n describe dan dar e claime dt o b e effective. 2 6 I n on e experiment , tw o bubbler s containin g th e solu tio nwer e place din serie s in th e samplin g train . Hea dlevel s correspondin g t o abou t 2. 0 /xg/m 3 o f organi c lea dwer e obtaine din th e firs t bubbler , wherea s th e secon dgav e ablan k response , indicatin g tha t th e collectio n efficienc y o f th e firs t bubble r wa s essentiall y 10 0 percen t

an dtha t th e metho di s quan titative . Analyse s wer e accomplishe dwithatomi c absorptio n spectrometr y afte r chelatio no f

th e lea d an dextractio n int o a norgani c solvent . I t shoul db e noted , however , tha t

th e detectio nsensitivit y wa s lo w an dtha t

th e us e o f

bubbler s limit s th e sampl e volume . 4.2. 5 Samplin g fo rLea d i n Othe rMedi a I nsom e respects , samplin g fo r lea dinwater , soil , dustfall , o r

vegetatio nca nb e easie r tha nsamplin g fo r airborn e lead . However , th e samplin g condition s ma y b e equall y a s comple x an dhav e afirst-orde r impac t o n th e measurements . 4.2.5. 1 WATE R Heav y metal s may b e distribute dinwate r a s ions , a s chemica l complexes , o r a s specie s adsorbe do n suspende dmatter. 4 Method s fo r samplin g an d 4- 4P.5 1

analysi s o f

lea din wate r

hav e bee n extensivel y de scribed. 293 0 Sampl e container s ma y b e eithe r glas s o r plastic . Thedynamicso f th e wate r

bod y shoul db e considered , an ddefine dprocedure s an dprecaution s shoul db e followed. 4 A variet y o f procedures , eac h associate dwithparticula r objectives , exist s (e.g. , separatio n o f

dissolve dan dsuspende dlea dan d preservatio n o f

wate r sample s t o retai n thei r

origina l state) . Analysi s o f

lea din wate r

i s typicall y accomplishe d withatomi c absorptio n an demissio n spectroscopy , althoug hanalytica l method s fo r othe r medi aar e als o applicable . Th e natura l lea dconten t o f lake s an driver s lie s in th e rang e o f 1 t o 1 0 /ttg/liter , with a n averag e valu e o f

6. 6 /ug/lite r

fo r Nort hAmerica n rivers. 1 Thus , i t

i s commonl y foun dnecessar y t o concentrat e th e sampl e b y chelatin g an dextractin g th e lea do r

b y evaporatin g th e water. 3 Technique s fo r wate r analysi s hav e bee n reviewe drecentl y b y Fisherma n an dErdman. 3 1 4.2.5. 2 SOI L Lea din soi l sample s collecte dfro mnearl y 100 0 location s aroun dth e Unite dState s range s fro mles s tha n 1 0 t o abou t

70 0 ppm , withamea n concentra tio n o f 1 6 ppm. 3 Depositio n o f lea do n soi l fro mth e atmospher e result s in extrem e vertica l concentratio n gradients , sinc e lea di s relativel y immobil e insoil. 4 I t ha s bee n estimate dtha t a n averag e o f

1 /xg Pb/cm 2 ' yea r

fro mrainou t

o r washou t o r both , an d 0. 2 fig Pb/cm 2 ' yea r

fro mdus t

accumulate s at

o r nea r th e soi l surface. 3 2 Horizonta l gradient s o f lea d concentration s in soi l occu r a s th e resul t

o f natura l an dmanmad e sources . Th e lea dconten t o f soi l decrease s rapidl y wit hdistanc e fro memissio n sources ; fo r

example , reduction s o f 7 5 percen t

ar e observe din movin g fro m8 t o 3 2 mfro mahigh way. 3 3 Thi s poin t

i s discusse din detai l in Chapte r 6 . Soi l samplin g i s no t

complex. 4 Vegetatio nan d larg e object s shoul db e avoided , an darepre sentativ e sit e shoul db e selected . Th e vertica l in tegrit y o f th e sampl e shoul db e preserve dan dnoted . Th e sampl e shoul db e air-drie dan dstore din seale d containers . Th e samplin g shoul db e planne dt o ob tai n result s representativ e o f th e condition s bein g in vestigated . Mos t

o f th e analytica l procedure s use d fo r airborn e particulate s ar e applicabl e t o soils , bu t th e result s ma y no t

b e comparable . Man y tech niques , includin g optica l emissio n spectrography , X ra y spectrography , atomi c absorption , an dth e electro n microprob e hav e bee n use dfo r soi l lea d analysis. 3 X-ra y diffractio n ha s bee n use dt o analyz e soi l sample s fo r

lea demitte db y automobiles. 3 4 4.2.5. 3 DUSTFAL L Al l particle s suspende din ai r ar e affecte db y grav itationa l settling . Th e settlin g velocitie s o f large r particle s (^ 5 t o 1 0 fim) ar e suc htha t the y wil l b e transporte dshorte r

distance s tha nth e smalle r parti cle s ( < 1 fim), whic hhav e nearl y negligibl e settlin g velocities . Thu s dustfal l collection s ca n b e use dt o monito r th e dispersio no f

particulat e lea dfro ma specifi c source . Th e collection s ar e mad e b y placin g ope ncontainer s a t

appropriat e site s fre e o f overhea d obstructions. 91 0 Usin g bucket s t o measur e dustfal l ca n lea dt o inaccurat e data ; win deddie s create db y th e wall s o f

th e bucke t

ma y greatl y affec t

deposition . Th e dustfal l surfac e shoul db e smoot han dflat , pre sentin g a s littl e disturbanc e t o th e win da s possible . Thes e point s ar e discusse db y Patterson. 3 5 Dustfal l i s generall y reporte din unit s of gram s pe r squar e mete r

pe r mont h(g/m 2 -mo ) an dma y b e analyze db y th e method s describe dfo r particulate s collecte do n filters. 9 Th e "AST M Standar dMetho d fo r Collectio n an dAnalysi s o f Dustfall " provide s detaile dprocedures. 3 6 On e compariso no f lea d quantitie s collecte db y dustfal l an db y filtratio nin dicate dconsistentl y tha t th e lea dconten t

o f particu late s collecte db y filtratio nin th e high-volum e sample r wa s highe r

tha nin dustfall. 3 7 Thi s i s aresul t primaril y o f

th e lo w settlin g velocitie s o f th e smalle r particles , whic hmak e u p asignifican t fractio n o f

th e tota l particulate . 4.2.5. 4 VEGETATIO N Lea danalysi s o f

plan t tissue s ha s bee n les s exten siv e tha nstudie s in othe r media . Lea ddeposite do n lea f surface s b y fallou t

ca n b e remove dan d analyzed. 3 8 Lea dinplant s i s usuall y observe dt o b e les s tha n 1 figlg dr y weight , althoug hlevel s a s hig h a s 3 1 figlg hav e bee n cited. 1 Plant s ca n absor b solu bl e lea dfro msoils , bu t

mos t soi l lea di s inform s no t availabl e t o plants. 1 Leaf y portion s o f

plant s ofte n exhibi t highe r concentration s o f

lead , bu t

in general , a t leas t 5 0 percen t

o f thi s lea dca n b e remove db y washing. ' Sinc e th e presenc e o f lea dinsid e th e plant s may manifes t

differen t effect s tha ntha t

o n th e plan t surface , attempt s shoul db e mad e t o differentiat e be twee nthes e tw o conditions . Littl e mentio n appear s i nth e literatur e o f method s fo r

th e fieldsamplin g o f plan t lif e fo r environmenta l studies . Th e standar dmethod s an d procedure s usuall y ar e focuse do n statistica l sam plin g fo r determinatio no f

nutrien t element s i nfoo d crops . Plan t tissu e collectio nan dtreatmen t hav e bee n reviewe db y Skogerbo e e t al. 4 Samplin g o f

plan t 4- 5P.5 2

material s i s generall y carrie dou t b y rando mselec tio n o f th e indigenou s specie s representativ e o f a give n are ao f

interest . Wher e th e entir e plan t i s no t collected , emphasi s i s usuall y place do n th e portio n o f th e plan t consume db y herbivore s o r harveste dfo r market . I n developin g samplin g plans , ther e shoul d b e clos e coordinatio n betwee n plan t an danima l samplin g groups , especiall y wher e foodchain s ar e in volved . Befor e analysis , adecisio n mus t b e mad e a s t o whethe r o r no t th e plan t

materia l shoul db e washe d t o remov e surfac e contaminatio n fro mfallou t an d soi l particles . If

th e plant s ar e sample din astud y of tota l lea dcontamination , o r if the y serv e a s anima l foo dsources , washin g shoul db e avoided . If th e effec t o f lea do n plan t

processe s i s bein g studied , o r i f th e plan t i s asourc e o f

huma n food , th e plan t

sam ple s shoul db e washed . I n eithe r case , th e decisio n mus t b e mad e a t

th e tim e o f

sampling , a s washin g canno t b e effectivel y use dafte r th e plan t

material s hav e dried . Neithe r

ca n fres hplan t

sample s b e store dfo r

an y lengt ho f

tim e in atightl y close dcon taine r befor e washing , becaus e mold s an denzymati c actio n ma y affec t

th e distributio n o f

lea do n an din th e plan t tissues . Freshl y picke dleave s store din seale dpolyethylen e bag s at roo mtemperatur e generall y mol di n afe w days . Storag e tim e ma y b e increase dt o approximatel y 2 week s b y refrigeration . Method s reporte din th e literatur e fo r removin g surfac e contaminatio n var y considerably , rangin g fro mmechanica l wipin g wit hacamel-hai r brus ht o leachin g in minera l acid s o r EDTA . Remova l o f

sur fac e contaminatio n wit hminimu mleachin g o f con stituent s fro mlea f

tissu e ca n generall y b e ac complishe db y usin g dilut e solution s of selecte dsyn theti c detergent s followe db y rinsin g in deionize d water . Afte r collection , plan t

sample s shoul db e drie da s rapidl y a s possibl e t o minimiz e chemica l an d biologica l changes . Sample s tha t ar e t o b e store dfo r extende dperiod s o f

tim e o r t o b e groun dshoul db e oven-drie dfo r

a t leas t 4 h r a t 70° C t o arres t enzymati c reaction s an drende r th e plan t

tissu e amenabl e t o th e grindin g process . Storag e in seale d container s i s alway s advisable . 4.2.5. 5 FOODSTUFF S I n 1972 , lea dwa s include din th e Foo dan dDru g Administratio n Marke t Baske t Survey , whic hin volve s nationwid e samplin g o f food s representin g th e averag e die t

o f a n 18-year-ol dmal e (i.e. , th e in dividua l wh o o n astatistica l basi s eat s th e greates t quantit y o f

food). 3 9 Variou s foo ditem s fro mth e differen t foo dclasse s ar e purchase din loca l market s an dmad e u p int o meal s in th e proportio ntha t eac h foo dite mi s ingested ; the y ar e the n cooke do r other wis e prepare da s the y woul db e consumed . Food s ar e groupe dint o 1 2 foo dclasses , the ncomposite dan d analyze dchemically . Th e quantitie s represente din th e Tota l Die t

Surve y an dth e percentage s o f thes e food s groupe dinth e die t ar e presente dinTabl e 4-1 . TABL E 4-1 . DAILYFOO D INTAKE 3 9

I I I II I I V V V I VI I VII I I X X X I XI I Foo d grou p Dairyproduct s Meat , fish , an d poultr y Grai n an d cerea l product s Potatoe s Leafyvegetable s Legum e vegetable s Roo t vegetable s Garde n fruit s Fruit s Oils , fats , an d shortenin g Suga ran d adjunct s Beverage s (includin g water ) Tota l Foo d consumptio n Avg . g/da y consume d 75 6 29 0 36 9 204 5 9 7 4 34 8 8 21 7 5 2 8 2 69 7 292 2 % o l

tota l die t 26. 1 9. 9 12. 6 7. 0 2. 0 2. 5 1. 2 3. 0 7. 4 1. 8 2. 8 24. 9 4.2. 6 Sourc e Samplin g Source s o f

lea dhav e bee nwel l identifie dan din clud e automobiles , smelter s (lea dan dothe r non ferrou s metals) , coal-burnin g facilities , batter y manufacturin g plants , chemica l processin g plants , an dfacilitie s fo r

scra p processin g an dweldin g an d solderin g operations . A n importan t secondar y sourc e i s fugitiv e dus t

fro mminin g operation s an d fro msoil s contaminate dwit hautomotiv e emis sions. 3 4 A complet e discussio n o f source s o f

lea d emission s i s give n in Chapte r 5 . Th e followin g sec tion s discus s th e samplin g o f stationar y an dmobil e sources , whic hrequir e differen t samplin g methods . 4.2.6. 1 STATIONAR Y SOURCE S Samplin g o f

stationar y source s fo r

lea drequire s th e us e o f

asamplin g trai n a t

th e sourc e t o sampl e th e effluen t

stream . Bot hparticulate s an dvapor s mus t b e collecte db y th e samplin g train , an dofte na prob e i s inserte ddirectl y int o th e stac k o r exhaus t stream . I nth e tentativ e AST M metho dfo r samplin g fo r atmospheri c lead , ai r i s pulle dthroug ha 0.45-/x mmembran e filte r an da n activate dcarbo n adsorptio n tube. 4 0 I nastud y o f manua l method s fo r 4- 6measurin g emissio n concentration s o f lea dan dothe r toxi c materials, 4 1 us e o f afilter , asyste mo f

im pingers , ameterin g system , an dapum p wa s recom mended . Th e recommende dsolutio n inth e im pinger s wa s nitri c acid . Mor e recently , impinge r solution s containin g iodin e monochlorid e hav e bee n show n t o b e effective. 2 6 Sinc e lea din stac k

emission s ma y b e presen t in a variet y o f

physica l an dchemica l forms , sourc e sam plin g train s mus t

b e designe dt o tra p an dretai nbot h gaseou s an dparticulat e lead . 4.2.6. 2 MOBIL ESOURCE S A variet y o f

procedure s ha s bee n use dt o obtai n sample s o f

aut o exhaus t

aerosol s fo r

subsequen t analysi s fo r

lea dcompounds . I n on e suc hprocedure , alarg e horizonta l ai r dilu tio n tub e wa s designe dt o segregat e fine combustion derive daerosol s fro mlarge r lea dparticle s ablate d fro mcombustio n chambe r an dexhaus t

deposit. 4 2 I n thi s procedure , ho t

exhaus t wa s ducte dint o a56-cm diameter , 12-m-long , ai r dilutio n tunne l an dmixe d withfiltere dambien t

ai r in a20-m-diamete r

mixin g baffl e in aconcurren t

flo w arrangement . Tota l ex haus t an ddilutio n ai r

flow rat e wa s 2 8 t o 3 6 m 3 /min , whic hproduce daresidenc e tim e o f abou t 5 se c in th e tunnel . A t

th e downstrea men do f th e tunnel , sample s o f

th e aeroso l wer e obtaine db y mean s o f isokineti c probe s facin g upstream , usin g filter s o r cascad e impactors . Properl y designe dai r dilutio n tube s o f thi s typ e hav e ver y few aeroso l losse s fo r particle s smalle r

tha n abou t

2 fim, th e siz e tha t

ca n b e respire dint o huma n lungs. 4 3 Air-dilute daerosol s fro mcycli c aut o emission s test s hav e bee n accumulate din alarg e plasti c bag . Filtratio n o r

impactio n o f

aerosol s fro mth e ba g sample s produce s sample s suitabl e fo r lea d analysis. 4 4 Becaus e o f

th e rathe r

length y residenc e time , th e ba g techniqu e ma y resul t in th e measure men t o f anomalousl y larg e aeroso l size s becaus e o f condensatio n o f

low-vapor-pressur e organi c sub stance s ont o th e lea dparticles . Thi s effec t ma y b e offset , however , b y fallou t processe s tha t

appl y pri maril y t o large r

particle s (se e above) . A low-residence-tim e samplin g syste mha s bee n use dtha t i s base do n proportiona l samplin g o f ra w exhaust , followe db y ai r dilutio n an dfiltratio n o r impaction. 45 ^ 4 6 A relativel y larg e sampl e o f aeroso l constituent s ca n b e obtaine dbecaus e o f th e hig h samplin g rate s o f

th e ra w exhaust . Sinc e aconstan t proportio n o f

th e sampl e flo w t o th e tota l exhaus t flow mus t

b e maintained , thi s techniqu e ma y b e limite db y th e respons e tim e o f th e equipmen t

t o operatin g cycl e phase s tha t caus e relativel y smal l transient s in th e exhaus t flo w rate . Mos t researc ho naeroso l emission s in recen t year s ha s use dvariou s configuration s o f th e horizonta l ai r dilutio n tunnel. 4 2 Severa l polyviny l chlorid e dilu tio ntunnel s hav e bee n use dwit hgoo dsuccess. 43474 8 Thes e 46-cm-diamete r

tunnel s o f

varyin g length s hav e bee n limite db y exhaus t temperature s t o tota l flows abov e approximatel y 1 1 m 3 /min . Buildu p o f electrostati c charg e o n th e wall s o f thes e plasti c system s ca n caus e abnormall y hig hwal l losses , bu t thes e ca nb e avoide db y wrappin g th e tunne l wit ha grounde dconductiv e cabl e a t abou t 30-c minter vals. 4 7 Simila r

tunnel s hav e bee n use di n whic ha centrifuga l fanlocate dupstrea mi s use drathe r tha n apositiv e displacemen t pum p locate d downstream. 4 3 Thi s geometr y produce s asligh t posi tiv e pressur e inth e tunne l an dexpedite s transfe r o f th e aeroso l t o holdin g chamber s fo r studie s o f

aero so l growth . Sinc e th e tota l exhaus t plu s dilutio n ai r flo w i s no t

hel dconstan t

in thi s system , ther e ma y b e sligh t sampl e disproportionation . However , thes e error s ca n b e minimize db y maintainin g aver y hig h dilutio n air/exhaus t

flo w ratio. 4 3 Ther e hav e als o bee nanumbe r o f studie s per forme dusin g tota l filtratio n o f th e exhaus t

strea mt o arriv e a t materia l balance s fo r

lea dusin g rathe r

lo w back-pressur e meta l filters. 4549

- 5 1 Th e cylindrica l filtratio n uni t

use dinthes e studie s i s bette r tha n 9 9 percen t effectiv e in retainin g lea dparticles. 5 1 Sup portin g dat afo r

lea dbalance s generall y confir mthi s conclusion. 5 2 Thu s awid e variet y o f

samplin g an dtota l exhaus t filtration procedure s hav e bee n use dt o measur e th e mas s emission s o f

lea dcompound s fro mauto mobiles . Eac hha s it s appropriat e are ao f appli cation , dependin g o nth e objective s o f th e variou s researc hprogra mcarrie dout . Th e ai r dilutio n tun ne l techniqu e i s mos t

convenient , i s compatibl e with th e usua l ga s emissio n measurements , an dha s therefor e bee nmos t

commonl y used . 4.2. 7 Filte rSelectio n an d Sampl e Preparatio n I nsamplin g fo r

lea dparticulates , ai r i s draw n throug hfilte r

material s suc ha s fiber glass , asbestos , cellulosi c paper , o r

porou s plastics. 2 4 Thes e material s includ e trac e element s tha t ca ninterfer e in th e subsequen t

analysis. 535 5 I f

th e sampl e i s large , the n th e effect s o f

thes e trac e element s ar e negligi ble , bu t thi s i s no t

alway s th e case. 5 6 Whe nsample s ar e prepare dfo r

analysis , reductio n o f th e mas s o f filte r materia l i s ofte naccomplishe db y ashing , eithe r chemicall y o r

ina n oven. 4 Th e natur e o f th e 4- 7P.5 4

filter determine s th e ashin g technique . I n othe r method s o f

analysi s —X-ra y fluorescence , fo r ex ampl e — analysi s ca n b e performe ddirectl y o nth e filte r i f th e filte r

materia l i s suitable. 1 6 Becaus e th e natur e an dperformanc e o f filter material s ar e stil l unde r investigation , genera l criteri afo r thei r selec tio n canno t

b e given. 4 A genera l revie w o f filte r material s i s available. 5 7 Th e mai n advantage s o f glass-fibe r

filter s ar e thei r lo w pressur e dro p an dhig hparticl e collectio n effi cienc y a t hig hflo w rates . Th e mai n disadvantag e i s th e variabl e lea dcontent . I n on e investigatio n o f Nuclepor e filters , example s wer e give n i n whic hth e analysi s o f

sample s an dblank s showe dresult s tha t di dno t diffe r sufficientl y t o allo w us e o f th e data. 4 Other s hav e show n tha t th e variabilit y o f

residua l impuritie s in som e glas s filter s make s thei r us e inad visabl e in mos t

cases, 545 5 an dthe y plac e ahig h priorit y o n th e standardizatio n o f asuitabl e filte r

fo r high-volum e samples. 5 6 Othe r investigation s hav e indicated , however , tha t glass-fibe r

filter s ar e avail abl e no w tha t

d o no t presen t alea dinterferenc e problem. 5 8 Th e collectio n efficiencie s o f filters , an d als o o f impactors , hav e bee n show n t o b e dominan t factor s in th e qualit y o f

th e derive ddata. 5 9 Th e rela tiv e effectivenes s o f

dr y ashin g (eithe r

a t lo w tem perature s in a n oxyge n plasm ao r a t hig htem peratures ) an do f

we t ashin g b y aci ddissolutio ni s a subjec t o f curren t concern . Eithe r

techniqu e wil l giv e goo dresult s if

employe dproperly. 45 5 4. 3 ANALYSI S A variet y o f

usefu l analytica l procedure s i s avail abl e fo r determinatio n o f

lea din th e environmenta l samples . Th e choic e o f th e bes t metho din agive n situatio n depend s o n th e natur e o f th e dat arequired , th e typ e o f

sampl e bein g analyzed , th e skil l o f th e analysts , an dth e equipmen t available . Fo r

genera l determinatio n o f

elementa l lead , atomi c absorptio n spectroscop y i s comin g int o wide r use . However , if multielemen t

analysi s i s required , an dif th e equip men t i s available , X-ra y fluorescence ha s bee n show n t o b e capabl e o f rapid , inexpensiv e analyses. 1 6 Othe r

analytica l method s hav e specifi c advantage s tha t

cal l fo r

thei r continue dus e in specia l studies . Onl y thos e analytica l technique s receivin g curren t

us e in lea danalysi s ar e describe d in th e following . Mor e complet e review s ar e availa bl e in th e literature. 342 9 4.3. 1 Colorimetri cAnalysi s Colorimetri c o r

spectrophotometri c analysi s fo r lea dusin g dithizon e (diphenylthiocarbazone ) a s th e reagen t ha s bee n use dfo r

man y years. 60 " 6 2 Thi s metho di s th e primar y on e recommende di n aNa tiona l Academ y o f

Science s repor t

o n lead, 1 an di t

i s th e basi s o f

th e tentativ e metho do f testin g fo r

lea din th e atmospher e b y th e America nSociet y fo r Testin g an dMaterials. 4 0 Becaus e o f it s history , i t

ha s serve d a s areferenc e b y whic hothe r method s hav e bee n tested . Dithizon e i s a n organi c compoun dtha t react s wit h lea dsalt s t o forma nintensel y colore dchelate dcom plex . Thi s comple x ha s a n absorptio n maximum , withaknow nextinctio ncoefficient , a t awavelengt h o f 51 0 nm , whic hi s th e basi s o f th e measurement . Standard s ca n b e prepare dfo r calibratio npurpose s b y addin g know n quantitie s o f lea dt o reagents . Th e procedure s fo r

th e colorimetri c dithizon e analysi s requir e askille danalys t i f reliabl e result s ar e t o b e obtained . Th e metho dha s bee nanalyzed, 4 an dth e procedure s ar e give nin th e literature. 44 0 Th e America nSociet y fo r Testin g an dMaterial s conducte dacollaborativ e tes t o f th e dithizon e method 6 3 an dconclude dtha t th e AST M dithizon e procedur e gav e satisfactor y precisio ninth e deter minatio no f

particulat e lea di nth e atmosphere . Th e colorimetri c dithizon e metho dha s th e advan tag e o f acceptabilit y b y professiona l organizations . I naddition , th e require dapparatu s i s simpl e an d relativel y inexpensive , th e absorptio ni s linearl y re late dt o th e lea dconcentration , th e metho drequire s onl y afew microgram s o f lea din th e sample , larg e sample s ca nb e used , an dinterference s ca nb e removed. 4 Realizatio no f thes e advantage s depend s o n meticulou s attentio n t o th e procedure s an d reagents . Thi s require s arelativel y length y pro cedur e an dthu s ahig hcos t pe r sample . 4.3. 2 Atomi cAbsorptio n Analysi s Atomi c absorptio n (AA ) spectroscop y i s th e mor e generall y accepte dmetho dfo r th e measuremen t

o f lea din environmenta l sampling. 4 A variet y o f lea d studie s usin g A A analysi s hav e bee n re ported. 26

. 55

. 58

. 64

- 6 5 I nAA , th e lea ddeterminatio ni s mad e b y measur in g th e resonanc e absorptio n o f lea datoms . Th e at tenuatio n o f

th e ligh t bea mpassin g throug hth e sam pl e i s logarithmicall y relate dt o th e concentratio n o f th e atom s bein g measured . Th e lea datom s inth e sampl e mus t

b e vaporize deithe r

inaprecisel y con trolle dflame o r

inanonflam e medium . Th e sampl e solutio n enter s th e flame throug hanebulizer . Th e lea dabsorptio n wavelength s ar e precisel y a t 217. 0 n man d283. 3 nm . Thes e wavelength s ar e produce d in ahollo w cathod e lam p containin g lead . Th e ligh t 4- 8beam , afte r passin g throug hth e flame , i s separate d in amonochromato r

an ddetecte dwit haphoto multiplier . A A require s frequen t us e o f calibratio n standard s t o obtai n precisio n an daccuracy . Typica l precisio n i s 1 t o 5 percent . Severa l hundre dsample s ca n b e analyze din a n 8-h r da y if sampl e preparatio n procedure s ar e simple . I n a n analysi s usin g A A an dhigh-volum e samplers , atmospheri c concentration s o f lea dwer e foun dt o b e 0.6 3 ± 0.3 0 ng/sc ma t th e Sout hPole. 6 4 Lea danalyse s o f

99 5 particulat e sample s fro mth e NAS N wer e accomplishe db y A A t o a nindicate d precisio n o f

1 1 percent , wit ha0.1 5 /ug/m 3 detectio n limit. 5 8 Atomi c absorptio n require s a s muc hcar e a s othe r technique s t o obtai n highl y precis e data . Back groun dabsorption , chemica l interferences , back groun dligh t

losses , an dothe r

factor s ca ncaus e er rors . A majo r

proble mwit hA A i s tha t i t ha s becom e s o popula r

tha t untraine doperator s ar e usin g i t in man y laboratories . Bu t fo r genera l purposes , A A i s th e mos t readil y applicabl e o f

an y o f th e analytica l methods . Technique s fo r

A A ar e stil l evolving , an dim prove dperformanc e involvin g nonflam e atomiza tio n systems , electrode-les s discharg e lamps , an d othe r equipmen t

refinement s an dtechniqu e development s ar e t o b e expected. 4 4.3. 3 Anodi cStrippin g Voltammetr y Electroanalytica l method s o f microanalysi s base d o n electrochemica l phenomen aar e foun din a variet y o f

forms. 666 7 The y ar e characterize db y a hig hdegre e o f

sensitivity , selectivity , an daccurac y derive dfro mth e relationship s betwee ncurrent , charge , potential , an dtim e fo r electrode s in solu tions . Th e electrochemistr y o f lea di s base dpri maril y o n th e plumbou s ion , whic hbehave s reversi bl y i n ioni c solution s an dha s areductio npotentia l nea r -0. 4 vol t

versu s astandar dcalome l electrode. 4 Voltammetry , th e electrometri c metho dwit h greates t sensitivit y fo r

lead , i s discusse dhere . Othe r method s ar e describe din th e reference s cite dabove . Anodi c strippin g voltammetr y (ASV ) describe s th e proces s b y whic hth e componen t o f interest , lead , i s selectivel y deposite do n a n electrod e b y reductio n in orde r t o concentrat e th e component. 6 6 Th e work in g electrod e ma y b e amercur y filmo nawax impregnate dgraphit e electrode . Afte r al l o f th e lea d in solutio n i s reduce dont o th e electrode , th e analysi s involve s astrippin g process . I n this , th e lea d i s oxidize db y mean s o f alinearl y variabl e voltag e tha t i s applie dt o th e electrode . Th e voltammogram , aplo t o f curren t versu s voltage , show s apea k corres pondin g t o th e oxidatio no f th e lead . Th e are ao f

th e pea k correspond s t o th e quantit y o f lea dion s avail abl e at th e strippin g voltage . AS V wa s applie dt o th e analysi s o f lea di n 2-h r sample s obtaine dwit haspo t tap e sampler. 1 9 Be twee n 8 0 n g an d2. 4 /xg o f lea dwa s presen t

in th e samples . Th e averag e standar ddeviatio n obtaine din th e lea dmeasurement s wa s 5. 9 percent . A detaile d procedur e fo r

sampl e preparatio n an danalysi s ha s bee npublished. 1 9 Voltammetr y wa s als o use din analysi s o f particu lat e lea dcollecte db y a nimpacto r fro mth e ambien t atmosphere. 6 8 Lea dconcentration s foun dwer e in th e 600 - t o 3000-ng/m 3 range . Curren t practic e withcommerciall y availabl e AS V equipmen t

allow s lea ddeterminatio n a t th e 1 pp b leve l wit hroutin e 5 - t o 10-percen t relativ e pre cision. 4 Extensio n t o 0.1-pp b level s i s attainabl e withmodifie dtechniques . Differentia l ASV 6 9 an ddifferential-pulse dASV 7 0 ar e reporte dt o giv e improve dsensitivit y an dt o facilitat e mor e rapi danalysis , thu s lowerin g th e cost . 4.3. 4 Emissio n Spectroscop y Optica l emissio nspectroscop y ha s bee n use dt o determin e th e lea dconten t o f soils , rocks , an d mineral s a t

th e 5 - t o 10-pp mleve l wit harelativ e standar ddeviatio no f

5 t o 1 0 percent; 6 2 thi s metho d ha s als o bee n applie dt o th e analysi s o f alarg e num be r o f ai r samples. 58

- 7 1 Th e primar y advantag e o f thi s metho di s tha t

it allow s simultaneou s analysi s fo r alarg e numbe r

o f element s inasmal l sampl e o f th e material . Emissio nspectroscop y essentiall y consist s o f ob servin g th e optica l emissio nspectr ao f materia l ex cite dinaspark , arc , o r flame . Th e wavelengt han d intensit y o f

th e characteristi c emissio n wavelength s o f th e element s provid e bot hqualitativ e an dquan titativ e dat ao n composition . Befor e 1960 , th e emis sio n spectromete r

wa s th e mos t

commo ninstrumen t in trace-detectio nlaboratories. 7 2 Whe nuse dfo r

asingl e elemen t

suc ha s lead , emis sio nspectroscop y i s at

adisadvantag e becaus e o f th e expens e o f

th e equipment , th e require dspecia l operato r training , an dth e us e o f photographi c fil m inth e detectio n process. 4 I nastud y o f environmen ta l contaminatio nb y automotiv e lead , samplin g time s wer e muc hreduce db y usin g asamplin g tech niqu e inwhic hlead-fre e porou s graphit e wa s use d bot ha s th e filte r

mediu man dth e electrod e inth e spectrometer. 707 3 Lea dconcentration s o f 1 t o 1 0 4- 9P.5 6

/xg/m 3 coul db e detecte dafte r ahal f hou r flo w at 80 0 t o 120 0 ml/mi n throug hth e filter . Scot t e t al . analyze dcomposite dparticulat e sam ple s obtaine dwithhigh-volum e sampler s fo r abou t 2 4 elements , includin g lead , usin g adirect-readin g emissio n spectrometer. 7 4 Ove r 100 0 sample s col lecte db y th e NAS N in 197 0 wer e analyzed . Carefu l consideratio n o f

accurac y an dprecisio n le dt o th e conclusio n tha t

optica l emissio n spectrometr y i s a rapi dan dpractica l techniqu e fo r analysi s o f

particu lates . 4.3. 5 Electro n Microprob e Whe n a n intens e electro n bea mi s inciden t o n a material , it

produces , amon g othe r form s o f

radia tion , X ray s whos e wavelength s depen do n th e ele ment s presen t

in th e materia l an dwhos e intensit y de pend s o n th e relativ e quantitie s o f thes e elements . Thi s X-radiatio n i s th e basi s o f th e electro n micro prob e metho do f

analysis . A n electro n bea mtha t give s aspo t

siz e a s smal l a s 0. 2 fim i s possible . Th e microprob e i s ofte n incorporate din ascannin g electro n microscop e tha t allow s precis e locatio n o f th e beam . Unde r

idea l conditions , th e analysi s i s quantitative , withan accurac y o f 1 t o 3 percent . Th e mas s o f th e analyze delemen t

may b e in th e IO 1 4 t o IO" 1 6 grange. 7 5 Te r Haa r an dBayard 7 6 applie dth e electro n microprob e metho dt o th e analysi s o f th e composi tio n o f airborn e lead-containin g particles . Particle s collecte do n membran e filter s wer e mounte do n specia l substrate s an danalyze dfo r lea dcom pounds. 7 6 Th e analysi s wa s base do n th e ratio s o f elementa l X-ra y intensities . Fro ma n environmenta l monitorin g viewpoint , th e abilit y t o determin e th e compositio n o f

comple x lea dparticulate s wit hhig h precisio n wa s demonstrated . Th e percentag e com positio n o f

lea dcompound s in th e sampl e range d fro malo w o f

0. 1 percen t

t o ahig ho f

ove r 3 7 per cent . Electro n microprob e analysi s i s no t awidel y ap plicabl e monitorin g method . I t require s expensiv e equipment , comple x sampl e preparation , an dahigh l y traine doperator . Th e metho di s unique , however , in providin g compositio n informatio n o n individua l lea dparticles , thu s permittin g th e stud y o f dynami c chemica l change s an dperhap s allowin g improve d sourc e identification . 4.3. 6 X-Ra y Fluorescenc e X-ra y fluorescen t

emission s tha t

characteriz e th e elementa l conten t

o f asampl e occu r

whe n atom s ar e irradiate da t

sufficien t

energ y t o remov e a n inner shel l electron. 4 Thi s fluorescenc e allow s simultaneou s identificatio no f arang e o f

elements , includin g lead . Fo r

example , 2 2 element s wer e iden tifie dan dquantitativel y analyze dinparticulat e sample s fro mdichotomou s sampler s withou t inter mediat e sampl e preparation. 1 6 Thi s analytica l metho di s identica l t o tha t describe dfo r

th e electro n microprob e inth e precedin g sectio nbu t utilize s differen t excitatio n sources . X-ra y fluorescence require s ahigh-energ y irradia tio nsource . X-ra y tubes, 16 ' 2 3 electro n beams, 7 5 an d radioactiv e isotop e sources 7 7 hav e bee nuse dexten sively. 78 ' 7 9 T o reduc e background , secondar y fluorescers hav e bee n employed. 1 6 Th e fluorescent X-ra y emissio nfro mth e sampl e ma y b e analyze d withacrysta l monochromato r an ddetecte dwith scintillation , wit hproportiona l counters, 4 o r wit h low-temperatur e semiconducto r detector s tha t discriminat e th e energ y o f th e fluorescence . Th e lat te r techniqu e require s aver y lo w leve l o f excita tion. 1 6 X-ra y emissio n induce db y charged-particl e ex citatio n(proton-induce dX-ra y emission , o r PIXE ) offer s a n attractiv e alternativ e t o th e mor e commo n techniques. 80 " 8 2 Recognitio no f th e potentia l o f heavy-particl e bombardmen t fo r excitatio n occur re din 1970 , an da ninterference-fre e sensitivit y dow n t o th e picogra mrang e wa s demonstrated. 8 0 Th e excellen t

capabilit y o f

accelerato r

beam s fo r

X ra y emissio n analysi s i s partiall y du e t o th e relativel y lo w backgroun dradiatio n associate dwit h th e excitation . Th e mai n contributio ni s Bremsstrahlun g fro msecondar y electro nemission . Th e hig hparticl e fluxes obtainabl e fro maccelera tor s als o contribut e t o th e sensitivit y o f th e PIX E method . Literatur e reviews 83 " 8 6 o napproache s t o X ra y elementa l analysi s agre e tha t proton s o f

afew Me V energ y provid e apreferre dcombinatio n fo r hig hsensitivit y analyse s unde r condition s les s sub jec t t o matri x interferenc e effects . A s aresul t o f thi s premise , asyste mdesigne dfo r routin e analysi s ha s bee n described, 8 1 an dpaper s involvin g th e us e o f PIX Efo r

aeroso l analysi s hav e recentl y ap peared. 81 ' 8 2 Advantage s o f

X-ra y fluorescence method s in clud e th e abilit y t o detec t avariet y o f

elements , th e abilit y t o analyz e wit hlittl e o r n o sampl e prepara tion , an dth e availabilit y o f automate danalytica l equipment . Disadvantage s includ e th e nee dfo r lo w blan k filters , expensiv e equipment , liqui dnitroge n (e.g. , fo r

energy-dispersiv e models , an dhighl y traine danalysts . Th e detectabilit y leve l fo r lea di s abou t 2 0 ng/cm 2 of

filter area , whic hi s wel l belo w 4-1 0th e quantit y obtaine din norma l samplin g period s

wit hth e dichotomou s sampler. 1 6 4.3. 7 Method s fo rCompoun d Analysi s Colorimetry , atomi c absorption , an danodi c strip pin g voltammetr y ar e restricte dt o measuremen t o f tota l lea dan dthu s canno t identif y th e variou s com pound s o f

lead . Th e electro n microprob e an dothe r X-ra y fluorescenc e method s provid e approximat e dat ao n compound s o n th e basi s o f th e ratio s o f

ele ment s present. 7 6 Ga s chromatograph y usin g th e electro n captur e detecto r ha s bee n demonstrate dt o b e usefu l fo r

organi c lea dcompounds. 2 8 Powde r X ra y diffractio n technique s hav e bee n applie dt o th e identificatio n o f

lea dcompound s i n soil. 3 4 4. 4 CONCLUSION S T o monito r

lea daeroso l in air , samplin g wit hth e high-volum e sample r

an danalysi s b y atomi c absorp tio n spectrometr y hav e emerge da s th e mos t widel y use dmethod . Samplin g in thi s way doe s no t provid e for fractionatio n o f

th e particle s accordin g t o size , no r doe s i t allo w determinatio n o f th e gaseou s (organic ) concentrations ; thes e capabilitie s ma y prov e importan t

fo r specia l studies . Th e siz e distri butio n o f

lea daeroso l i s importan t in considerin g question s regardin g exposur e b y inhalation ; sam plin g wit hcascad e impactor s o r dichotomou s sampler s i s necessar y t o suc hevaluations . T o deter min e gaseou s lead , i t

i s necessar y t o bac k

th e filte r wit hchemica l scrubber s o r acrystallin e iodin e trap . X-ra y fluorescenc e an doptica l emissio n spectroscop y ar e applicabl e t o multielemen t analysi s an dar e convenien t

t o appl y t o th e measuremen t o f lea din suc hstudies . Becaus e o f th e man y environ menta l variable s implici t in sit e monitoring , th e developmen t

o f usefu l biologica l monitorin g techni que s ma y b e o f

mor e direc t

utility . 4. 5 REFERENCE S FO RCHAPTE R4 1 . Lead : Airborn e Lea di n Perspective . Nationa l Academ y o f Sciences , Washington , D . C . 1972 . 33 0 p . 2 . Stern , A . C . (ed.) . Ai r Pollution . 2n ded . Academi c Press , Ne w York , 1968 . 3 . Lovering , T . G . (ed.) . Lea di n th e Environment . Geologi ca l Surve y Professiona l Pape r 957 . U.S . Governmen t Printin g Office , Washington , D.C . 1976 . 9 0 p . 4 . Skogerboe , R . K. , A . M . Hartley , R . S . Vogel , an dS . R . Koirtyohann . Monitorin g fo r lea di n th e environment . In: Lea di n th e Environment . (W . R . Boggs , ed.) . Repor t t o NSF ® RANN . U.S . Governmen t Printin g Office , Washing ton , D.C . 1977 . (I n press. ) 5 . Ott , W . R . Developmen t o f criteri afo r

sitin g ai r

monitor in g stations . In: Proc . 68t hAnnua l Meeting , Ai r Pollutio n Contro l Association , Boston , Vol . 2 , Pape r No . 75-14.2 . Jun e 1975 . 1 7 p . 6 . Guidelines : Ai r Qualit y Surveillanc e Networks . U.S . En vironmenta l Protectio n Agency , Offic e o f Ai r Programs , Researc hTriangl e Park , N.C . Publicatio n No . AP-98 . Ma y 1971 . 1 6 p . 7 . Samplin g Locatio n Guidelines . U.S . Environmenta l Pro tectio n Agency , Divisio n o f Atmospheri c Surveillance . Novembe r

1972 . 8 . Watson , H . H . Error s du e t o anisokineti c samplin g o f aerosols . Am . Ind . Hyg . Assoc . Q . /5(l):21-25 . 1954 . 9 . Warner , P . O . Analysi s o f Ai r Pollutants . Joh n Wile y & Sons , Ne w York . 1976 . 32 9 p . 10 . Ai r Qualit y Criteri afo r

Particulat e Matter . U.S . Dept . o f Health , Education , an dWelfare , Nationa l Ai r Pollutio n Contro l Administration , Washington , D.C . Publicatio n No . AP-49 . 1969 . 11 . Wedding , J . B. , A . R . McFarland , an dJ . E . Cermak . Larg e particl e collectio n characteristic s o f ambien t

aeroso l samplers . Envir . Sci . Tech . //:387 , 1977 . 12 . Davidson , C . I . Ph.D . Dissertation . Calif . Inst . Tech nology , Pasadena , Calif . 1977 . 1 3 . Berlin , A. , P . De l Castilho , an dJ . Smeets . Europea n inter compariso n programs . In: Environmenta l Healt hAspect s o f Lead . Commissio n o f

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Lo s Angele s smog . J . Colloi dInterfac e Sci . J9(l) : 177-204 , 1972 . 15 . Lippmann , M . an dW . B . Harris . Size-selectiv e sample s fo r estimatin g "respirable " dus t concentrations . Healt h Physics . 8(2):155-163 , 1962 . 16 . Dzubay , T . G . an dR . K . Stevens . Ambien t ai r analysi s wit hdichotomou s sample r an dX-ra y fluorescenc e spectrometer . Environ . Sci . Tech . 9(7):633-688 , 1975 . 17 . Dzubay , T . G. , L . E . Hines , an dR . K . Stevens . Particl e bounc e error s i

n cascad e impactors . Atmos . Environ . / 0:229-234 , 1976 . 18 . Goulding , F.S. , J . M . Jaklevic.an dB . W . Loo . Fabricatio n o f monitorin g syste mfo r determinin g mas s an dcomposi tio n o f aeroso l a s afunctio n o f time . Prepare dunde r

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No . EPA-IAG-D4-037 7 b y th e Law renc e Berkele y Laboratory , Universit y o f California , Berkeley , Calif . U.S . Environmenta l Protectio nAgency , Washington , D.C , an dth e Nationa l Environmenta l Researc hCenter , Chemistr y an dPhysic s Laboratory . Re por t No . EPA-650/2-75-048 . 1975 . 3 8 p . 19 . Macleod , K . E . an dR . E . Lee , Jr . Selecte dtrac e meta l determinatio n o f

spo t tap e sample s b y anodi c strippin g voltammetry . Anal . Chem . 45(14):2380-2383 , 1973 . 20 . Lee , R . E. , Jr . an dS . Goranson . Nationa l ai r surveillanc e cascad e impacto r

network . I . Siz e distributio n measure ment s o f suspende dparticulat e matte r i n air . Environ . Sci . Technol . 6( 1 2) : 1019-1024 , 1972 . 21 . Rossano , A . T. , Jr . (ed.) . Ai r Pollutio n Contro l Guideboo k fo r Management . E . R . A. , Inc. , Stanford , Conn . 1969 . 22 . Lee , R . E. , Jr. , S . S . Goranson , R . E . Enrione , an dG . B . Morgan . Nationa l ai r

surveillanc e cascad e impacto r net work . II . Siz e distributio n measurement s o f trac e meta l components . Environ . Sci . Technol . 6( 1 2):1025-1030 , 1972 . 23 . Paciga , J . J . an dR . E . Jervis . Multielemen t siz e charac terizatio n o f

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24 . Bernstein , D . J. , M . T . Kleinman , T . J . Kneip , T . L . Chan , an d M . Lippmann . Ahig h volum e sample rfo rth e deter minatio n o f particl e siz e distribution s i n ambien t air . J . Ai rPollut . Contro l Assoc . 26( 1 I ):1069-1072 , 1976 . 25 . Lundgren , D . A . A n aeroso l sample rfo rdeterminatio n o f particl e concentratio n a s a functio n o f siz e an d time . J . Ai r Pollut . Contro l Assoc . /7(4):225-229 , 1967 . 26 . Purdue , L . J. , R . E . Enrione , R . J . Thompson , an d B . A . Bonfield . Determinatio n o f organi can d tota l lea d i n th e atmospher e b yatomi cabsorptio n spectrometry . Anal . Chem . 45(3):527-530 , 1973 . 27 . Harrison , R . M. , R . Perry , an d D . H . Slater . Th e contribu tio n o f organi clea d compound s t o tota l lea d i n urba n at mospheres . In:

Internationa l Symposiu m Proceedings : Re cen t Advance s i n th e Assessmen t o f th e Healt h Effect s o f Environmenta l Pollution , Vol . 111 . Commissio n o f th e Europea n Communities . Luxembourg . 1975 . p . 1783-1788 . 28 . Shapiro , H . an d F . W . Frey . Th e Organi cCompound s o f Lead , lnterscienc e Publishers . Joh n Wile yan d Sons , Inc. . Ne wYork . 1968.486p . 29 . Standar d Method s fo rth e Examinatio n o f Wate ran d Wastewater . 13t h Ed . Amer . Publi cHealt h Assoc , Wash ington , D.C . 1971 . 30 . Kopp , J . F . an d R . C . Kroner . Trac e Metal s i n Water s o f th e Unite d States . U.S . Dept . o f th e Interior , Federa l Wate rPollutio n Contro l Administration , Cincinnati , Ohio . 1967 . 21 8 p . 3 1 . Fishman , M . J . an d D . E . Erdmann . Wate ranalysis . Anal . Chem.45(5):361R-403R . 1973 . 32 . Te rHaar , G . L. , R . B . Holtzman , an d H . F . Lucas . Lea d an d lead-21 0 i n rainwater . Nature . 2/6(51131:353-355 , 1967 . 33 . Lagerwerff , J . V . an d A . W . Specht . Contaminatio n o f roadsid e soi l an d vegetatio n wit h cadmium , nickel , lead , an d zinc . Environ . Sci . Technol . 4(7):583-586 , 1970 . 34 . Olson , K . W . an d R . K . Skogerboe . Identificatio n o f soi l lea d compound s fro m automotiv e sources . Environ . Sci . Technol . 9(3):227-230 , 1975 . 35 . Patterson , C . C . Repor t o f th e Exper t Meetin g o n Dr y Deposition . Worl d Meteorologica l Organization . Gothen burg , Sweden . 36 . America n Societ yfo rTestin g an d Materials . Standar d metho d fo rcollectio n an d analysi s o f dustfal l (settleabl e particulates) . D 1 739-70 . Annu . Boo k AST M Stand . Pt . 26 : 517-521 , 1975 . 37 . Hinners , T „ J . Kent , W . Terrill , T . Heiderscheit , R . Bur ton , an d A . V . Colucci . Metal s i n Atmospheri cParticu late s Collecte d b yH i Vo l Sample ran d b yDustfal l Bucket . U.S . Environmenta l Protectio n Agency , Researc h Triangl e Park.N.C . 1972 . 5 3 p . 38 . Smith , W . H . Meta l contaminatio n o f urba n wood yplants . Environ . Sci . Technol . 7(7):631-636 , 1973 . 39 . Kolbye , A . C , Jr. , K . R . Mahaffey , J . A . Fiorino , P . C . Corneliussen , an d C . F . Jelinek . Foo d exposure s t o lead . Environmenta l Healt h Perspectives . Experimenta l Issu e No . 7 , Ma y1974 . 40 . America n Societ yfo rTestin g an d Materials . Tentativ e metho d o f tes t fo rlea d i n th e atmospher e b ycolorimetri c dithizon e procedure . D3112-72T . Annu . Boo k AST M Stand . Pt . 26:633-641 , 1975 . 4 1 . Coulson , D . M. , D . L . Haynes , M . F . Balazs , an d M . P . Dolder . Surve yo f Manua l Method s o f Measuremen t o f Asbestos , Beryllium , Lead , Cadmium , Selenium , an d Mer cur yi n Stationar ySourc e Emissions . U.S . Environmenta l Protectio n Agency , Researc h Triangl e Park , N.C . Pub . No . EPA-650/4-74-015 . 1953 . 42 . Habibi , K . Characterizatio n o f particulat e lea d i n vehicl e exhaust—experimenta l techniques . Environ . Sc . Technol . 4(3):239-248 , 1970 . 43 . Trayser , D . A. , E . R . Blosser , R . A . Creswick , an d W . R . Pierson . Sulfuri caci d an d nitrat e emission s fro m oxida tio n catalysts . SA E Tech . Pap . (750091):!-15 , 1975 . 44 . Te rHaar , G . L. , D . L . Lenane , J . N . Hu , an d M . Brandt . Composition , size , an d contro l o f automotiv e exhaus t par ticulates . J . Ai rPollut . Contro l Assoc . //(l):39-46 , 1972 . 45 . Sampson , R . E . an d G . S . Springer . Effect s o f exhaus t ga s temperatur e an d fue l compositio n o n particulat e emissio n fro m spar k

ignitio n engines . Environ . Sci . Technol . 7(l):55-60 , 1973 . 46 . Ganley . J . T . an d G . S . Springer . Physica l an d chemica l characteristic s o f particulate s i n spar k ignitio n engin e ex haust . Environ . Sci . Technol . S(4):340-347 , 1974 . 47 . Moran , J . B. . M . J . Baldwin , O . J . Manary , an d J . C . Valenta . Effec t o f fue l additive s o n th e chemica l an d physica l characteristic s o f particulat e emission s i n automotiv e exhaust . U.S . Environmenta l Protectio n Agen cy . Researc h Triangl e Park , N . C . Pub . No . EPA-R2-72 - 066 . 1972 . 48 . Gentel . J . E. . O . J . Manary . an d J . C . Valenta . Charac terizatio n o f particulate s an d othe rnon-regulate d emis sion s fro m mobil e source s an d th e effect s o f exhaus t emis sion s contro l device s o n thes e emissions . U.S . Environ menta l Protectio n Agency , An n Arbor , Mich . No . APTD-1567 . 1973 . 49 . Hirschler , D . A. . L . F . Gilbert , F . W . Lamb , an d L . M . Niebylski . Particulat e lea d compound s i n automobil e ex haus t gas . Ind . Eng . Chem . 49(1):\ 131- 1 142 , 1957 . 50 . Hirschler , D . A . an d L . F . Gilbert . Natur e o f Lea d i n ex haus t gas . Arch . Environ . Health . 5:297-313 . 1964 . 5 1 . Habibi , K . Characterizatio n o f particulat e matte ri n vehi cl e exhaust . Environ . Sci . Technol . 7(3):223-224 . 1973 . 52 . Kunz , W . G. , Jr. . E . S . Jacobs , an d A . J . Pahnke . Desig n an d performanc e o f muffle rlea d trap s fo rvehicles . Pre sente d befor e Unio n Indersyndica l d e I'ndustri e d u Petrole . Paris , France . Januar y1975 . 53 . Gandrud , B . W . an d A . L . Lazrus . Desig n o f syste m fo r removin g water-solubl e material s fro m IPC-147 8 filte r paper . Environ . Sci . Technol . 6(5):455-457 , 1972 . 54 . Luke , D . L. , T . Y . Kometani , J . E . Kessler , T . C . Loomis , J . L . Bove , an d B . Nathanson . X-ra yspectrometri c analysi s o f ai rpollutio n dust . Environ . Sci . Technol . 6(13): ! 105- 1 109 , 1972 . 55 . Kometani , T . Y. , J . L . Bove , B . Nathanson , S . Sieben berger , an d M . Magyar . Dr yashin g o f airborn e particulat e matte ro n pape ran d glas s fiberfilter s fo rtrac e meta l analysi s b yatomi cabsorptio n spectrometry . Environ . Sci . Technol . 6(7):617-620 , 1972 . 56 . Witz , S . an d R . D . Macphee . Effec t o f Differen t Type s o f Glas s Filter s o n Tota l Suspende d Particulate s an d Thei r Chemica l Compounds . Souther n Californi a Ai rPollutio n Contro l District , Tech . Service s Report . Jul y1976 . 9 p . 4-1 257 . Skogerboe , R . K . Monitorin g trac e meta l particulates : A n evaluatio n o f th e samplin g an d analysi s problems . Ameri ca n Societ yfo rTestin g an d Materials , Philadelphia , Pa . Specia l Pub . 555:125-136 , 1974 . 58 . Scott , D . R. , W . A . Loseke , L . E . Holboke , an d R . J . Thompson . Atomi cabsorptio n an d optica l emissio n analysi s o f NAS N atmospheri cparticulat e sample s fo r lead . Environ . Sci . an d Technol . /0.877-88O . 1976 . 59 . Skogerboe , R . K. , D . L . Dick , an d P . J . Lamothe . Evalua tio n o f filte rinefficiencie s fo rparticulat e collectio n unde r lo wloadin g conditions . Atmos . Environ . //(3):243-249 , 1977 . 60 . Sandell , E . B . Colorimetri cDeterminatio n o f Trace s o f Metals , lnterscienc e Publishers , Inc. , Ne wYork . 1944 . 6 1 . Horowitz , W. , P . Chichilo , an d H . Reynold s (eds.) . Offi cia l Method s o f Analysi s o f th e Associatio n o f Officia l Analytica l Chemists . I 1t h Ed . Associatio n o f Officia l Analytica l Chemists , Washington , D . C . 1970 . 101 5 p . 62 . Officia l Standardize d an d Recommende d Method s o f Analysis . W . Heffe ran d Sons , Ltd , Cambridge , Mass . 1963 . 63 . Foster , J . F. , G . H . Beatty , an d J . E . Howes , Jr . In terlaborator yCooperativ e Stud yo f th e Precisio n an d Ac curac yo f th e Measuremen t o f Lea d i n th e Atmospher e Usin g th e Colorimetri cDithizon e Procedure . America n Societ yfo rTestin g an d Materials , Philadelphia , Pa . AST M Dat a Serie s Pub . DS55-S5 . 1975 . 7 9 p . Zoller , W . H. , E . S . Gladney , an d R . A . Duce . At mospheri cconcentration s an d source s o f trac e metal s a t th e Sout h Pole . Science . 183:\ 98-200 , 1974 . Huntzicker . J . J. . S . K . Friedlander , an d C . I . Davidson . Materia l balanc e fo rautomobile-emitte d lea d i n Lo s Angele s Basin . Environ . Sci . Technol . 9(5):488-457 , 1975 . 66 . Willard , H . H. , L . L . Merritt . Jr. , an d J . A . Dean . Instru menta l Method s o f Analysis . 5t h ed . D . Va n Nostran d Co . Ne wYork . 1974 . 86 0 p' . Sawyer , D . T . an d J . L . Roberts . Jr . Experimenta l Electrochemistr yfo rChemists . Wile yan d Sons , Ne w York . 1974 . Harrison . P . R. . W . R . Matson . an d J . W . Winchester . Tim e variation s o f lead , copper , an d cadmiu m concentra tion s i n aerosol s i n An n Arbor . Michigan . Atmos . En viron . 5:613-619 . 1971 . Zirino , A . an d M . L . Healy . ph-controlle d differentia l voltammetr yo f certai n trac e transitio n element s i n natura l waters . Environ . Sci . Technol . 6(3)243-249 , 1972 . 70 . Copeland.T . R.J . H . Christie , R . K . Skogerboe , an d R . A . Osteryoung . Effec t o f supportin g electrolyt e concentratio n i n pulse d strippin g voltammetr ya t th e thi n fil m mercur y electrode . Anal . Chem . 45(61:995-996 , 1973 . 71 . Environmenta l Contaminatio n Cause d b yLead . Prepare d unde rNS F Grant s GI-34813X I an d GI-4442 3 b yCol orad o Stat e University , For t Collins , Colo . H . W . Edward s (ed.) . Interi m repor t fo rth e perio d Januar yI t o Decembe r 3 1 , 1974 . 6 4 6 5

6 7 6 8

6 9 72 . Ward , F . N . an d M . J . Fishman . Analytica l method s fo r th e determination s o f lead . In: Lea d i n th e Environmen t (T . G . Lovering , ed.) . U.S . Geologica l Surve yProfessiona l Pape r957:

81-84 , 1976 . 73 . Seeley , J . L . an d R . K . Skogerboe . Combine d sampling analysi s metho d fo rth e determinatio n o f trac e element s i n atmospheri cparticulates . Anal . Chem . 46(3):415-421 . 1974 . 74 . Scott , D . R. . W . A . Loseke . L . E . Holboke , an d R . J . Thompson . Analysi s o f atmospheri cparticulate s fo rtrac e element s b yoptica l emissio n spectrometry . Appl . Spectrosc . J0(4):392-405 , 1976 . 75 . T . D . McKinley , T . D . an d K . F . J . Heinric h (eds.) . Th e Electro n Microprobe . Joh n Wile yan d Sons , Inc . Ne w York . 1966 . 103 5 p . 76 . Te rHaar , G . L . an d M . A . Bayard . Compositio n o f air born e lea d particles . Natur e 232:553-554 , 1971 . 77 . Kneip , T . J . an d G . R . Lauer . Isotop e excite d X-ra y fluorescence . Anal . Chem . 44( I4):57A-58A . 1972 . 78 . Birks , L . S . X-ra yabsorptio n an d emission . Anal . Chem . 44(5):557R-562R . 1972 . 79 . Birks . L . S. . J . V . Gilfrich . an d D . J . Nagel . Large-Scal e Monitorin g o f Automobil e Exhaus t Particulate—Method s an d Costs . NR L Memorandu m Repor t 2350 . Nuclea r Scienc e Division . Nava l Researc h Laboratory . Washing ton . D.C . 1971 . 2 6 p . 80 . Johansson . T . B. . R . Akselsson . an d S . A . E . Johansson . X ra yanalysis : Elementa l trac e analysi s a t th e 10" 1 2 level . Nucl . Instrum . Method s (Eng.) . 84(I):!4 I -143 . 1970 . 8 I . Johansson . T . B. . R . E . Va n Grieken . J . W . Nelson , an d J . W . Winchester . Elementa l trac e analysi s o f smal l sample s b yproton-induce d X-ra yemission . Anal . Chem . 47(61:855-860 . 1975 . 82 . Hardy . K . A . R . Akselsson . J . W . Nelson , an d J . W . Winchester . Elementa l constituent s o f Miam i aeroso l a s a functio n o f particl e size . Environ . Sci . Technol . /0(2):I76-182 . 1976 . 83 . Walter , R . L. . R . D . Willis , W . F . Gutknecht , an d J . M . Joyce . Analysi s ofbiological . clinical , an d environmenta l sample s usin g proton-induce d X-ra yemission . Anal . Chem . 46(71:843-855 . 1974 . 84 . Gilfrich . J . V . P . G . Burkhalter . an d L . S . Birks . X-ra y spectrometr yfo rparticulat e ai rpollution— Aquantitativ e compariso n o f techniques . Anal . Chem . '45(121:2002-2009 . 1973 . 85 .

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### 4-1 3

## 5 . SOURCE S AN D EMISSION S

5. 1 NATURA L SOURCE S Lea denter s th e biospher e fro mlead-bearin g mineral s in th e lithospher e throug hbot hnatura l an d human-mediate dprocesses . Measurement s o f sur fac e material s take n a t

8-in . depth s in th e continen ta l Unite dStates 1 sho w amedia n lea dconcentratio n o f 1 5 ppm . Ninety-fiv e percen t o f thes e measure ment s sho w 3 0 pp mo f

lea do r less , wit hamaximu m sampl e concentratio n o f 70 0 ppm . I n natura l pro cesses , lea di s firs t

incorporate din soi l in th e activ e soi l zone , fro mwhic hi t ma y b e absorbe db y plants , leache dint o surfac e waters , o r erode dint o windborn e dusts. 2 5 I n addition , minut e amount s o f radioactiv e 210 P b reac hth e atmospher e throug hth e deca y o f rado n ga s release dfro mth e earth. 6 Becaus e lea dha s bee n use dfo r centuries , i t

i s difficul t t o determin e th e rang e o f natura l back groun dlevels . Calculation s o f natura l contribution s usin g geochemica l information , however , indicat e tha t natura l source s contribut e arelativel y smal l amoun t o f lea dt o th e environment . Fo r example , i

f th e typica l 2 5 t o 4 0 ju-g/m 3 o r rura l airborn e particu lat e matte r

wer e derive dfro msurfac e material s con tainin g 15 , an drarel y mor e tha n 30 , pp mlea da s cite dabove , the n th e natura l contributio n t o air born e lea dwoul drang e fro m0.000 4 t o 0.001 2 Mg/m 3

. I n fact , level s a s lo w a s 0.001 2 t o 0.02 9 /ug/m 3 hav e bee n measure da t asit e in California' s Whit e Mountains. 7 I n contrast , however , annua l averag e lea dconcentration s in urba n suspende dpar ticulat e matter 8 rang e a s hig ha s 6 /Lig/m 3

. Clearly , therefore , mos t

o f thi s urba n particulat e lea dstem s fro mman-mad e sources . 5. 2 MAN-MAD E SOURCE S 5.2. 1 Productio n Lea doccupie s a n importan t positio n in th e U.S . economy , rankin g fourt hamon g th e nonferrou s metal s in tonnag e used . Th e pattern s o f it s flo w throug hindustr y ar e identifie din Figur e 5-1. 9 Ap proximatel y 8 5 percen t o f th e primar y lea dpro duce din thi s countr y i s fro mnativ e mines, 1 0 wher e it i s ofte n associate dwit hmino r amount s o f

zinc , cad mium , copper , bismuth , gold , silver , an dothe r

minerals. 1 0 Missour i or e deposit s accoun t fo r abou t 8 0 percen t

o f th e domesti c production . EXTERNA L EMISSION S

SCRA P 59 8

DOMESTI C ORE S 48 3 FOREIG N ORE S 9 6 META L IMPORT S 9 0 SECONDAR Y

PLANT S 51 2

PRIMAR Y PLANT S 58 2 TOTA L

SUPPL Y 136 3 META L PRODUCT S 24 5 CERAMIC S AN D PIGMENT S 7 2 ALKYL S 19 0 BATTERIE S 63 4 OTHE R 3 6 EXPOR T 1 9 UNREPORTE D USE S AN D STOC K CHANGE S 18 7 Figur e 5-1 . Approximat

e flo wo f lead throug h U.S . industr y i n 1975 , metri c tons. 9 5.2. 2 Utilizatio n Th e reporte duse s o f

lead , liste db y majo r

produc t categorie s in Tabl e 5-1, " stoo da t nearl y 1. 2 millio n M T in 1975 , wit ha n estimate dconsumptio n fo r 197 6 o f 1.3 5 millio n MT. 1 2 Certai n products , especiall y batteries , cables , plumbing , weights , an dballast , contai nlea dtha t i s economicall y recoverabl e a s secondar y lead . Thi s reserv e o f

lea dinus e i s estimate da t 3. 8 millio nMT , o f whic habou t

0. 6 millio n M T i s recovere dan nually . Lea dinpigments , gasolin e additives , am munition , foil , solder , an dstee l product s i s widel y disperse dan dtherefor e i s largel y unrecoverable . 5- 1P.6 1

TABL E 5-1 . U.S . CONSUMPTIO N O F LEA D B YPRODUC TCATEGORY 1 1 (MT/yr ) Produc t categor y Storag e batterie s Gasolin e antiknoc k additive s Pigment s an d ceramic s Ammunitio n Solde r Cabl e covering s Caulkin g lea d Pip e an d shee t lea d Typ e meta l Bras s an d bronz e Bearin g metal s Weigh t ballas t Othe r Tota l 197 1 616,58 1 (679,803) a 239,66 6 (264,240 ) 73,70 1 (81,567 ) 79,42 3 (87,567 ) 63,50 2 (70,013 ) 47,99 8 (52,920 ) 27,20 4 (29,993 ) 41,52 3 (45,781 ) 18,87 6 (20,812 ) 18,18 0 (20,044 ) 14,77 1 (16,285 ) 15,83 0 (17,453 ) 41,12 8 (45,345 ) 1,298,38 3 (1,431,514 ) 197 2 661,74 0 (729,592 ) 252,45 4 (278,340 ) 80,91 7 (89,214 ) 76,82 2 (84,699 ) 64,65 9 (71,289 ) 41,65 9 (45,930 ) 20,39 2 (22,483 ) 37,59 2 (41,447 ) 18,08 9 (19,944 ) 17,96 3 (19,805 ) 14,43 5 (15,915 ) 19,32 1 (21,302 ) 43,80 3 (48,294 ) 1,349,846 (1,488,254 ) 1973 697,88 8 (769,447 ) 248,89 0 (274,410 ) 98,65 1 (108,766 ) 73,09 1 (81,479 ) 65,09 5 (71,770 ) 39,00 6 (43,005 ) 18,19 2 (20,057 ) 40,52 9 (44,685 ) 19,88 3 (21,922 ) 20,62 1 (22,735 ) 14,20 1 (15,657 ) 18,90 9 (20,848 ) 42,11 0 (46,428 ) 1,397,87 6 (1,541,209 ) 1974 772,65 6 (851,881 ) 227,84 7 (251,210 ) 105,40 5 (116,213 ) 78,99 1 (87,090 ) 60,11 6 (66,280 ) 39,38 7 (43,426 ) 17,90 3 (19,739 ) 34,23 8 (37,749 ) 18,60 8 (20,516 ) 20,17 2 (22,240 ) 13,25 0 (14,609 ) 19,42 6 (21,418 ) 42,68 0 (47,056 ) 1,450,679 (1,599,427 ) 1975 634,36 8 (699,414 ) 189,36 9 (208,786 ) 71,71 8 (79,072 ) 68,09 8 (75,081 ) 52,01 1 (57,344 ) 20,04 4 (22,099 ) 12,96 6 (14,296 ) 35,45 6 (39,092 ) 14,70 3 (16,211 ) 12,15 7 (13,404 ) 11,05 1 (12,184 ) 18,15 6 (20,018 ) 36.36 8 (40,097 ) 1,176,465 (1,297,098 ) a Shor t lons/y rgive n i n parentheses . 

### 5.2. 3 Emission s Leado r it s compound s ma

y ente r th e environmen t a t an y step durin g it s mining , smelting , processing , use , or disposal . Recent

estimate s o

f th e dispersal o

f leademission s into th e environmen t b y principal source s indicat e that

th e atmosphere i s th e major in itial recipient . Estimate dlea demission s t o th e at mosphere i

n 197 5 ar e shown i

n Tabl e 5-2 . Mobil e an dstationary source s o f lea demissions , althoug hfoundthroughou t th e nation , ten dt o be concentrate di

n area s o f highpopulatio n density , wit hth e exceptio n o

f smelters . Figure 5- 2 show s th e approximat e location s of

major leadmines , primary smelters , alky l leadplants , andmanufacturer s o f leadstorag e batteries. 1 3 

### 5.2.3. 1 MOBIL ESOURCE S Th e larges t

source , b y far , o f leademission s t o th e atmosphere i s th e exhaus t o f moto r vehicle s powere d b y gasolin e tha t

contain s leadadditives. 1 4 

### Thes e mobile-sourc e emission s collectivel y constitut e a n estimate d8 8 percen t

o f tota l lea demission s (Tabl e 5-2). 9 

### Othe r

mobil e sources , includin g aviatio n usag e of leade dgasolin e an ddiese l an dje t fue l com bustion , contribut e insignificant leademission s t o th e atmosphere . Leadparticulate s emitte di n automotiv e exhaus t ma y b e divide dinto tw o siz e classes . Particle s in itiall y forme db

y condensatio n o

f leadcompound s i

n th e combustio n gase s ar e quit e smal l i n siz e (well under 0. 1 fim i

n diameter) . Particle s i

n thi s siz e categor y that become airborn e ca

n remai n sus pende di n th e atmosphere fo

r long period s an dthu

s ca n trave l substantial distance s fro mth e original sources . Large r

particle s ar e als o forme da s aresult o f agglomeratio n o

f smalle r condensatio n particles . 5- 2TABL E 5-2 . ESTIMATE D ATMOSPHERI C LEA D EMISSION S FO R TH E UNITE D STATES , 1975»•» Sourc e categor y Annua l emissions , MT/y r Emission s a s percentag e o f Subtota l Mobil e subtota l 142,00 0 10 0 Gasolin e combustio n Stationar ysubtota l Wast e oi l combustio n Soli d wast e incineratio n Coa l combustio n Oi l combustio n Gra yiro n productio n Iro n an d stee l productio n Secondar ylea d smeltin g Primarycoppe rsmeltin g Or e crushin g an d grindin g Primarylea d smeltin g Othe rmetallurgica l Lea d alky l manufactur e Typ e meta l Portlan d cemen t productio n Pigment s Miscellaneou s Tota l 142,00 0 19,22 5 10 0

10 0 10,43 0 1,63 0 40 0 10 0 1,07 9 84 4 75 5 61 9 49 3 •40 0 27 2 1,01 4 43 6 31 3 11 2 54. 3

8. 5 2.1 ' 0. 5 5. 6 4. 4 3. 9 3. 2 2. 5 2. 1 1. 4 5. 3 2. 3 1. 6 0. 6 32 8 161,22 5 1. 7 88. 1 6. 5 1. 0 0. 2 0. 1 0. 7 0. 5 0. 4 0. 4 0. 3 0. 2 0. 2 0. 6 0. 3 0. 2 0. 1 0. 2 10 0 a Inventor ydoe s no t includ e emission s fro m exhaustin g workroo m air . burnin g o f lead-painte d surfaces , weldin g of lead-painte d stee l structures , o rweatherin g o f painte d surfaces .

O LEA D SMELTIN G AN D REFININ G PLANT S (7) ; • TETRAMETHY L AN D TETRAETHY L LEA D PLANT S (5 ) PRIMAR YPRODUCTIO N FO R 197 6 = 652 , 87 7 M T ASTORAG E BATTER YMANUFACTURER S ( > 188 ) Figur e 5-2 . Locatio n o

f majo r lea d operation s i n th e Unite d States , 1976. 1 ' • LEA D MINE S (2 5 LARGEST) ; PRODUCTIO N = > 95 % O F DOMESTI C OUTPU T 5-3P.6 3



### Thes e large r

particles , whic

hma y b e ten s o

f micrometer s or

larger i n diameter , behav e i

n th e at mosphere lik

e th e larger

leadparticulate s emitte d fro mmos t stationary source s andfall t o th e groun d i n th e vicinit

y o f th e traffi c producin g them . Th e dis tributio n o

f leadexhaus t

particle s between th e smaller an dlarge r

siz e range s appear s t o depen don anumber o f factors , includin g th e particular drivin g pattern i n whichth e vehicl e i s usedan dit s pas t driv in g histor y (Chapte r

6) . Bu t a s a n overal l average , it ha s bee n estimated 1 5 

### that

durin g th e lifetime o

f th e vehicle , approximatel y 3 5 percen t o f th e leadcon taine di n th e gasolin e burne db

y th e vehicl e wil l b e emitte da s fine particulate , an dapproximatel y 4 0 percen t wil l b e emitte das coars e particulate . Th e re mainde r o f th e lea dconsume di

n gasolin e combus tio n i s deposite di

n th e engin e andexhaus t

system . Engin e deposit s are , i

n part , graduall y transferre dt o th e lubricatin g oi l andremove dfro mth e vehicl e whe n th e oi l i s changed . Moreover , som e oil s an d lubricant s contai n lea

dnaphthenat e a s adetergent . Th e fat e o f spent oi l an dit s lea

dconten t i s o f con siderabl e importance . A measure o f it s significanc e i s reflecte di

n th e wast e oil combustio n value s i

n Ta bl e 5-2 . In addition , som e o f th e leaddeposite di

n th e exhaus t

syste mgraduall y flake s off

, i s emitte di

n th e exhaus t

a s extremel y larg e particles , an drapidl y fall s into th e street s an droad s wher e i t i s incorpor ate dinto th e dus t

an dwashe dint o sewer s o r ont o ad jacen t soil . Th e us e o f leadadditive s i

n gasoline , whichwas increasin g i

n tota l volum e fo

r man y years , i s no

w decreasin g a s car s designe dt o us e lead-fre e gasolin e constitut e agrowin g portio n o f th e total automotiv e populatio n (see Section 7.1.1) . Regulation s promul gate db y EPA 1 6 

### that

limi t th e averag e concentratio n o f lea dadditive s i

n gasolin e will contribut e t o a further reductio n i

n future automotiv e leademis sions . 5.2.3. 2 STATIONAR Y SOURCE S A s show n i n Tabl e 5- 2 (base do

n 197 5 emission estimates 9 

### ) , soli dwast

e incineratio n an dcombustio n o f wast e oi l ar e th e principa l contributor s o f lead emission s fro

mstationary sources , accountin g fo r two-third s o

f stationary sourc e emissions . Th e manufacture o

f consumer

product s sucha s lea

d glass , storag e batteries , an dleadadditive s fo r gasolin e als o contribute s significantly t o stationary sourc e leademissions . Sinc e 1970 , th e quantity o f lea demitte dfro

mth e metallurgica l industry ha s decrease dsomewha

t becaus e o

f th e applicatio n o

f contro l equipment

an dth e closin g o

f several plants , particularl y i n th e zin c andpyrometallurgica l indus tries . A ne w locu s fo

r leademission s emerge di n th e mid-sixties , however , wit hth e openin g o

f th e "Viburnu mTrend " o r

"New LeadBelt " i

n south easter n Missouri . Th e presenc e of seve n mine s an d tw o accompanyin g lea

dsmelter s i

n thi s are amake s i

t th e larges t

lead-producin g distric t

i n th e worl dan d ha s move dth e Unite dState s into firs t plac e amon g th e world' s |ead-producin g nations . A n extensiv e study t o asses s th e impac t o f th e expandin g lea

din dustr y i n Missouri an dt o stimulat e ne w emissio n contro l technolog y ha s been initiated. 1 7 

### Althoug hsom

e contaminatio n o

f soi l an dwater occur s a s aresul t

o f suchmechanism s as leachin g fro mmin e an dsmelter

wastes , quantitativ e estimate s o f th e extent

o f thi s contaminatio n ar e no t available . Spillag e o f or e concentrate s fro

mopen truck s an d railroa dcars , however , i s known t o contribut e sig nificantly t o contaminatio n alon g transportatio n routes . Fo r

example , alon g tw o route s usedb y ore truck s i n southeastern Missouri , lea dlevel s i n lea f litte r range dfro

m200 0 t o 500 0 figlg a

t th e road way , declinin g t o afairly constan t 10 0 t o 20 0 figlg beyon dabou t

40 0 f t fro mth e roadway. 1 7 

### Another possibl e sourc e o

f lan dor water con taminatio n i s th e disposal o f particulat e leadcol lecte db y ai r pollutio n contro l systems . Th e poten tial fo r impac t on soil andwater

system s o

f th e dis posa l o f dust s collecte db

y thes e contro l system s ha s no t been quantified . Th e lead-containin g particle s emitte dfro msta tionary source s occur

i n variou s sizes . Thos e emitte d fro muncontrolle dstationary source s generall y in clud e particle s larger

than 1 - t o 2-fim mas s mea n diameter , an dtherefore ten dt o settl e out nea r th e source . Thes e large-particle emission s ad dcon siderabl e leadt o th e dust , soil , water , an dvegetatio n i n th e neighborhoo do

f th e sourc e (se e Sectio n 7.2) . Uncontrolle dsource s als o contribut e substantial quantitie s o

f smaller-diamete r

particle s t o th e at mosphere , where iong-rang e transport ma y occur . When control s ar e applie dt o stationary sources , th e tota l mas s o

f th e emission s i s reduce dsignificantly . Bu t th e number

o f particle s bein g emitte dma y no t b e affectedgreatl y i

f mos t o f th e particle s emitte d ar e small , becaus e curren t particulat e contro l method s ar e usuall y more effectiv e i n removin g th e larger-diamete r

particles . Th e smaller-diamete r particle s (belo w 2 fim) ma y be fa r greate r i n number than th e larger , more massiv e particles ; an dwit h diminishin g size , a

n increasin g proportio n i s likel y t o escap e collection . Generally , contro l method s ar e 5-4

### applie dt o emission s fro mstacks , vents , an dothe r proces s outlets . Bu

t lead-containin g particle s ma y als o b e emitte da s fugitiv e dust s i n th e larger

siz e rang e (>2-fim diameter ) fro mles s controllabl e source s suchas window s an ddoors , conveyors , an d wast e piles . Availabl e emissio n inventorie s d o no t includ e emission s fro

mth e exhaus t

o f workroo mair , burnin g o

f lead-painte dsurfaces , weatherin g o f lead-painte dsurfaces , etc . Th e magnitud e o f emis sion s fro mthes e source s i s unknown . 5. 3 REFERENCE S FO RCHAPTE R5 1 . Shacklette , H . T. , J . C . Hamilton , J . G . Boerngen , an dJ . M . Bowles . Elementa l Compositio n o f Surficia l Material s in th e Conterminou s Unite dStates . U.S . Geologica l Survey . Washington , D.C . Professiona l Pape r 574-D . 1971 . 7 4 p . 2 . Chamberlain , A . C . Interceptio n an dretentio n o f radioac tiv e aerosol s b y vegetation . Atmos . Environ . 4:57-77 , 1970 . 3 . Chow , T . J . an dC . C . Patterson . Th e occurrenc e an dsig nificanc e o f

lea disotope s in pelagi c sediments . Geochim . Cosmochim . Acta . (London) . 26:263-308 , 1962 . 4 . Lead : Airborn e Lea din Perspective . Nationa l Academ y o f Sciences . Washington , D . C . 1972 . 33 0 p . 5 . Patterson , C . C . Contaminate dan dnatura l lea denviron ment s o f man . Arch . Environ . Health . 77:334-360 , 1965 . 6 . Burton , W . M . an dN . G . Stewart . Us e o f long-live d natura l radio-activit y a s an atmospheri c tracer . Nature . 756:584-589 , 1960 . 7 . Chow , T . J. , J . L . Earl , an dC . B . Snyder . Lea daeroso l baseline : Concentratio n at Whit e Mountai n an dLagun a Mountain , California . Science . 7 78(4059):401-402 , 1972 . 8 . Akland , G . G . Ai r

Qualit y Dat afo r

Metals , 197 0 throug h 1974 , fro mth e Nationa l Ai r Surveillanc e Network . U.S . 1 0 I I Environmenta l Protectio n Agency , Researc hTriangl e Park , N.C. , Pub . No . EP A 600/4-76-401 . 1976 . Contro l Technique s fo r Lea dAi r

Emissions . (Draf

t final report. ) Offic e o f

Ai r Qualit y Plannin g an dStandards , U.S . Environmenta l Protectio n Agency , Researc hTriangl e Park , N.C . EP A Contrac t No . 68-02-1375 . 1976 . 42 4 p . Minera l Fact s an dProblems . U.S . Burea u o f Mine s Bulleti n 667 , U.S . Departmen t o f Interior , Washington , D.C . 1975 . p . 1243 . Lea dIndustr y i

n Ma y 1976 . Minera l Industr y Surveys . U.S . Departmen t

o f Interior , Burea u o f

Mines , Washing ton , D.C . Augus t

1976 . Cited

in: Contro l Technique s fo r Lea dAi r

Emissions . (Draf

t fina l report. ) Offic e o f Ai r Qualit y Plannin g an dStandards , U . S . Environmenta l Pro tectio n Agency , Researc hTriangl e Park , N . C . EP A Con trac t No . 68-02-1375 . 1976 . 42 4 p . Commodit y Dat aSummaries , 1977 . U.S . Departmen t o f Th e Interior , Burea u o f Mines , Washington , D . C . Januar y 1977 . Commodit y Files , 1976 . U.S . Dept . o f Interior , Burea u o f Mines , Washington , D.C . 1976 . 14 . EPA' s Positio n o n th e Healt hImplication s o f Airborn e Lead . U.S . Environmenta l Protectio n Agency , Washing ton , D.C . 1973 . 11 6 p . Te r Haar , G . L. , D . L . Lenane , J . N . Hu , an dM . Brandt . Composition , size , an dcontro l o f automotiv e exhaus t

par ticulates . J . Ai r

Poll . Contro l Assoc . 22(l):39-46 , 1972 . Federa l Register . Regulatio n o f fuel s an dfue l additives . 5S(234):33 . 734-33 . 741 , Dec . 6 . 1973 . Wixson , B . G . an dJ . C . Jennet t (eds.) . An Interdisciplin ar y Investigatio n o f

Environmenta l Pollutio n b y Lea dan d Othe r Heav y Metal s fro mIndustria l Developmen t in th e Ne w Lea dBel t

o f Southeaster n Missouri . (Interi mreport. ) Nationa l Scienc e Foundation , Researc hApplie dt o Na tiona l Need s (RANN) , Roll aan dColumbia , Missouri , Th e Universit y o f

Missouri . 1974 . 48 0 p . 1 2 1 3

1 5 1 6 1 7



### 5- 5

## 6 . TRANSFORMATIO N AN D TRANSPOR T

6 1 INTRODUCTIO N Th e circulatio n o f

lea din th e environmen t (show n conceptuall y i n Figur e 6-1 ) illustrate s tha t lea d release dint o th e atmospher e ca. n b e delivere dt o ma n (animals ) vi asevera l routes . A t present , it

i s possibl e t o obtai n onl y qualitativ e o r semiquantita tiv e estimate s o f

th e movemen t

o f lea dwithi n an d amon g th e variou s environmenta l media . Thi s i s largel y becaus e th e physica l an dchemica l transfor mation s occurrin g withi n th e lea dcycl e ar e no t wel l understood . Th e purpos e o f thi s chapte r

i s t o sum mariz e th e availabl e dat atha t reflec t wha t i s know n abou t th e transformatio n an dtranspor t mechanism s controllin g th e distributio n and.fat e o f lea di n th e environmen t

in it s variou s chemica l forms . Primar y emphasi s i s place do n th e atmosphere , since.i t serve s a s th e principa l mediu mfo r transpor t

o f lea dfro m manmad e sources .

FOO D PROCESSIN G . ; WATE R : : : SUPPLIE S : :

> PLANT S •:•> : :•:•:•:•:•:•:•:•:•:•:• :

• EARTH : : ISOIL I : MININ G OPERATION S

JO'lN'D'OStR V > 

# u . r

# , , . » / ^.AUTOMOBILE S j —•- ; , L ± I

; ATMOSPHER E ; . I (LEA D AEROSO L \- : AN D ;'• ; ORGANI C LEAD ) ;'• :£:£;£ : "Ir^x^'oust':::::::!"^ ' Si::::::::::*:::*:::*:::*:* : OTHE R LEA D CONTAININ G PRODUCT S AN D WASTE S

" ' FALLOUT " " ly.'.; :-: : : : AN D RAINOU T'•:•:'•: 

## T 

## ~~ :':'.yy.'': OCEAN S #$ +

- * ^ESTUARIES - :; !

LAKE S AN D RIVER S

'•>:•:•: SEDIMENT S • : Figur e 6-1 . Simplifie d ecologi c flo wchar t fo r lea d showin g principa l cyclin g pathway s an d compartments . 6. 2 PHYSICA L AN D CHEMICA L TRANS FORMATION S I N TH E ATMOSPHER E Althoug hlea di s introduce dint o th e atmospher e primaril y in th e particulat e form , relativel y smal l amount s ar e als o emitte din th e vapo r phase . Onc e lea di s introduce dint o th e atmosphere , importan t physica l an dchemica l change s occu r befor e it s transfe r t o othe r environmenta l media . Th e discus sio no f thes e change s will b e divide dint o mobil e an d stationar y sourc e categories . Thi s divisio n i s some wha t arbitrar y in tha t

th e pollutant s fro mbot h sourc e categorie s ar e wel l mixe din th e atmosphere . I n thos e case s in whic hon e typ e o f sourc e predomi nate s (e.g. , freeway s o r smehers) , th e approac h shoul db e reasonabl y realistic . 6.2. 1 Physica l Transformation s 6.2.l. l SIZ EDISTRIBUTIO N O FPARTICLE S FRO M MOBIL ESOURCE S Automotiv e exhaus t

i s th e primar y sourc e o f par ticulat e lea dintroduce dubiquitousl y int o th e at mospher e in urba n areas . Th e siz e o f th e particle s emitte dmay rang e fro mafew hundredth s o f a micromete r

in diamete r

t o severa l millimeters , de pendin g o n th e operatin g mode , ag e o f exhaus t system , fuel lea dcontent , spee dan dload , accelera tion , deceleration , engin e condition , an dothe r fac tors . Numerou s environmenta l processes , includin g transformation , transport , deposition , an dmechan ism s o f impact , ar e prominentl y influence db y th e particl e sizes . I t

i s significant , fo r

example , tha t

th e size s o f th e particle s directl y affec t th e probabilit y o f lead' s bein g transporte dvi ath e respirator y system . Becaus e o f

th e importanc e o f

lea dparticl e size s in relatio n t o numerou s environmenta l questions , th e siz e distribution s o f

thos e particle s emitte dfro m automobile s hav e bee n studie db y man y investiga tors. 1 " 10

. Figur e 6- 2 show s th e result s o f aserie s o f

variabl e spee dtest s mad e b y Hirschle r an dGilbert 4 o n an aut o afte r

abou t 25,00 0 mile s o f

deposi t accumula 6- 1I i u p i I i •»•'»' " ' I P.6 6

tio n in th e exhaus t

system . Th e dat ademonstrat e tha t smalle r lea dparticle s mak e u p th e larges t frac tio n o f thos e exhausted , an dtha t ther e i s significan t exhaus t syste maccumulatio n o f lea dparticle s in bot hsiz e categorie s unde r city-drivin g conditions . Durin g acceleration , releas e o f thes e accumulation s i s quit e rapidl y induced , bu t th e increase demissio n drop s of f durin g th e perio do f constan t

highwa y speed . Th e effec t

o f spee do n th e particl e siz e distri butio n show n in Figur e 6-3 , a s foun db y Ganle y an d Springer, 3 als o demonstrate s tha t th e mea n particl e size s emitte ddecreas e wit hincreasin g speed . Th e result s o f

thes e tw o studie s impl y tha t althoug h large r lea dparticle s ar e mos t likel y t o b e deposite d in th e exhaus t

system , th e deposit s ar e release db y ablativ e processe s tha t caus e decrease s in particl e size . Figur e 6- 4 compare s siz e distribution s a t recep to r site s in Californi awit hthos e typica l o f undilute d aut o exhaust . Th e smalle r size s at th e recepto r

site s reflec t th e decreas e in th e mea n siz e cause db y gra vitationa l settlin g an dothe r scavengin g processe s tha t occu r durin g atmospheri c transport . Figur e 6- 5 compare s differentia l mas s distributi@n s a t th e Californi arecepto r

site s withthos e a t

afreewa y site . Thes e distribution s ar e generall y bimodal , indicat in g tha t particulat e lea din th e atmospher e may con sis t o f lea demitte db y auto s an dlea dtha t ha s bee n deposite do n surface s (soil ) an dre-entraine dvi aat mospheri c turbulenc e (fugitiv e dust) ; o r fihe bimoda l distributio n ma y reflec t emissio n patterns . Th e result s o f thes e studie s generall y indicau e tha t mor e tha n hal f o f th e lea dparticle s ar e typicall y les s tha n 1 fim in diameter , bu t

thes e estimate s ma y b e biase d b y th e failur e t o us e isokineti c samplin g technique s (se e Sectio n 4.2.3.1) . Le e e t al. 9 measure dth e concentration s an dsiz e distribution s o f

particulat e emission s fro mauto mobil e exhaus t

an dfoun dtha t

9 5 percen t

o f th e tota l particulat e lea dwa s in particle s withmas s me dia n equivalen t

diameter s (MMED ) les s tha n 0. 5 fim. Al l sample s wer e take n a t steady-cruis e condi tion s an dthu s d o no t

represen t

th e typica l discharg e o f particle s unde r

wide-open-throttl e accelerations , decelerations , an dshort-ter mcruis e an didl e condi tion s typica l o f

urba n traffic . Th e varyin g mode s resul t in th e discharg e o f

muc hlarge r

particles . Robinso n an dLudwig " reporte dMMIE D o f 0.2 5 fim fo r urba n an drura l areas ; 2 5 percen t o f th e par ticle s wer e smalle r

tha n 0.1 6 fim, an d2 5 percen t wer e large r

tha n 0.4 3 fim (Tabl e 6-1) . Chola k e t al., 1 2 Le e e t

al., 1 3 an dFlesch 1 4 observe dsimila r distributions ; however , thei r dat aals o indicat e tha t thes e distribution s chang e ver y littl e ove r distances . < 5 0 — 100 0 50 0

10 0 5 0

1 0 5 

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k CITY-TYP E DRIVIN G -* | o l l I 1 1 I I TOTA L LEA D EXHAUSTE D FIN E PARTICLES . 0- 5 u m _ AN D UNCLASSIFIE D LEAD : I COARS E PARTICLES , > 5 HI T A l 1 i - 

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f variou s drivin g condition s o n th e amoun t o f lea d exhausted. 4

3 0 4 0 5 0 6 0 7 0 8 0 9 0 PARTICLE S WIT H DIAMETE R <D,wl % Figur e 6-3 . Effec t o

fspee d o n siz e distributio n o f exhaus t par ticle s a t differen t roa d loa d cruis e condition s an d usin g In dolen e H O 0 fuel. 3 Gillett e an dWinchester 1 5 examine dth e effec t o f ag e o n th e siz e distributio no f lea daerosols . The y foun d tha t lea daeroso l siz e distribution s d o no t var y greatl y fro mon e sourc e are a(essentiall y a n are aof heav y automobil e traffic ) t o another , an dtha t th e 6- 2crometenUJ a UJOIAM UJPARTICNAMIC

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### / —

- —

_ —

—

—

_ — I. . 4 0 6 0 8 0 9 0 9 5 MAS S I N PARTICLE S < D , percen t Figur e 6-4 . Cumulativ e mas s distribution s fo r lea d aeroso l i n aut o exhaus t an d at Pasadena , a recepto r samplin g site . Th e absciss a i s a log-norma l scale , an d D

_i s th e aerodynamic , uni t density particl e diameter.'' '

0. 2 a. a ro < « -

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### .Nft ^ O 0. 2 —

0. 1 1. 0 1 0 MEA N DIAMETE R I D I , micrometer s Figur e 6-5 . Differentia l mas s distribution s fo r lea d 1 m fro m a freeway , Ma y 1973 , an d a t Pasaden a samplin g sites , Novem be r 1972 an d February 1974 . (Th e absciss a i s th e mea n diameter , an d th e dashe d line s assum e tha t th e smalles t par ticl e siz e i s 0.0 1 /u m an d th e larges t 5 0 /im . Alo g D p = inter va l of lo g o

f aerodynami c particl e diameter ; m T= total mas s loadin g o

f lea d i n airborn e particulates ; A m = mas s o f lea d occurrin g i n a fraction , define d i n term s o f size , o f th e tota l particulates ; im/m T= fractio n o f mas s occurrin g i n a give n particl e siz e range.) 1 " lea daeroso l siz e distribution s d o no t respon d noticeabl y t o change s in weathe r withi n asourc e are adurin g 24-h r

samplin g periods . Th e result s o f thei r stud y sugges t

littl e modificatio n o f

th e charac teristic s o f

th e lea daeroso l siz e distributio n a s a resul t o f nonprecipitativ e atmospheri c mechanism s fo r equivalen t

particl e radi i large r

tha n 0. 2 fim. Electro n microscop e studie s hav e show ntha t man y o f th e fin e particle s in exhaus t emission s ar e nearl y spherica l in shap e an dar e electron-dense . Th e coarse r

particle s ar e muc hmor e irregular , an d som e ar e filamentou s i n outline . Particle s collecte d at aconstan t

cruis e spee do f

3 0 mp hwer e foun dt o b e compose do f

acarbo ncor e o r

matrix , o n o r

in whic hwer e distribute dspherica l o r crystallin e electron-dens e lea dparticle s <0. l fim i n diameter. 31 6 Electro n micrograph s o f th e exhaus t particle s hav e show ntha t althoug hth e particl e ag gregate s o f

abou t 0. 5 fim wer e stable , sample s o f th e ga s tha t

ha dbee n inhale dshowe dmor e homogeneou s aggregate s I t o 2 micrometer s in diamete r tha n large r

aggregate s in th e exhale dgas . A simila r

effec t wa s obtaine db y drawin g th e ga s throug hahumidifier.' 7 6.2.1. 2 SIZ EDISTRIBUTIO N O FPARTICLE S FRO M STATIONAR Y SOURCE S High-temperatur e combustio nan dsmeltin g pro cesse s generat e submicrometer-size dlea dparticu late , wherea s lea demission s fro mmateria l handlin g an dmechanica l attritio n operation s associate dwit h smelter s consis t

o f large r ( > 1 fim) dus t

particles . Actua l dat ao n th e siz e distributio no f lea dparticle s emitte dfro mstationar y source s ar e limited . Fuga s e t al., 1 8 usin g afive-stag e impactor , obtaine dsample s in th e Mez aValle y (influence db y alea dsmelter ) an di n th e urba n are ao f Zagreb . Th e result s ar e show n i n Figur e 6-6 . A considerabl e differenc e wa s foun din th e siz e distributio no f lea dparticle s i n th e industria l (Mez aValley ) versu s th e urba n (Zagreb ) area . I n th e industria l area , onl y 1 0 percen t o f th e lea dparticle s ha ddiameter s smalle r an d1 fim, wherea s i n th e urba narea , 7 5 percen t wer e smalle r tha n 1 fim. Thi s implie s tha t th e fugitiv e dus t

fro m th e mechanica l rathe r tha nth e direct-smeltin g operatio n i s th e primar y emission . Lea demission s fro mstationar y source s ar e proba bl y affecte db y topographi c influence s i n amanne r simila r t o othe r

pollutants . Becaus e o f th e moun tainou s locatio no f

hal f o f th e si x primar y lea d smelter s i n th e Unite dStates , however , an dbecaus e thes e thre e smelter s ar e probabl y th e larges t single poin t emitter s o f

lead , th e topographi c influenc e o n transpor t an ddispersio n i s important . 6- 3P.6 8

TABL E 6-1 . COMPARISO N O F SIZ E DISTRIBUTION S O F LEAD-CONTAININ G PARTICLE S I N MAJO R SAMPLIN G AREAS 1 1

Sampl e are a Chicag o Cincinnat i Philadelphi a Lo s Angele s (DTN ) Pasaden a Verno n (rural ) Sa n Francisc o Cheroke e (rural ) Mojav e (rural ) No . O l sample s 1 2 7 7 8 7 5 3 1 1 25 %

Avg . 0.19(7) b 0.15(3 ) 0.14(3 ) 0.16(7 ) 0.1 8 0.17(4 ) 0.1 1 0.2 5 — Rang e

0.10-0.2 9 0.09-0.2 4 0.09-0.2 5 0.10-0.2 2 0.05-0.2 5 0.12-0.2 2 0.06-0.1 3 — — Distributi o

Avg . 0.3 0 0.2 3 0.2 4 0.2 6 0.2 4 0.2 4 0.2 5 0.3 1 0.2 7 i b yparticl e size . u, m

MMED a Rang e 0.16-.6 4 0.16-0.2 8 0.19-0.3 1 0.19-0.2 9 0.08-0.3 2 0.18-0.3 2 0.15-0.3 1 — — 75 %

Avg . 0.40(10 ) 0.44 0.4 1 0.49(7 ) 0.48(6 ) 0.4 0 0.45(2 ) 0.7 1 0.3 4 Rang e

0.28-0.6 3 0.30-0.6 8 0.28-0.5 6 0.39-0.6 0 0.13-0.6 7 0.28-0.4 7 0.44-0.4 6 — — MME D = mas s media n equivalen t diameter . Number s i n parenthese s indicat e numbe ro l sample s availabl e fo ra specifi cvalu e whe n differen t fro m tota l numbe ro f samples .

I I T MEZ A VALLE Y

ZAGRE B SEP-OC T197 1 JAINJ-FE B 197 2 _ MAY-JU L 197 2 " AUG-SE P 197 2 JAN-FE B 197 3 1 5 1 0 3 0 SO 7 0 9 0 9 5 9 9 MAS S < DIAMETER , percen t Figur e 6-6 . Cumulativ e mas s distributio n o f lea d particle s b

y size. 1 8 

### A t leas t fou r general conclusion s abou t leadfro m mobil e an dstationary source s ca n b e base don th e result s o f th e abov e studies : 1 . Leadi s emitte dint o th e atmosphere prin cipall y i n th e particulat e form . 2 . Th e mas s median equivalen t diameter s o

f th e lead-bearin g particle s ar e typicall y les s than l fim, andth e siz e distribution s ar e fairl y unifor mfro mare at o area . 3 . Th e particl e size s i

n urban an drura l area s ar e suchtha t

th e leadca

n b e transporte d over relativel y larg e distance s vi atypical at mospheri c convectio n an dturbulenc e pro cesses . 4 . Th e siz e distribution s are suchthat signifi cant fraction s o

f th e tota l atmospheri c lead concentration s ar e withi n th e respirabl e siz e range . 6.2. 2 Chemica l Transformations 6.2.2. 1 MOBIL ESOURC EEMISSION S Tetraethy l lead(TEL ) an dtetramethy l lead (TML) , a s well a s th e mixed-lea dalkyls , ar e used widely a s additive s i

n gasoline . Althoug hthes e organi c compound s ar e les s volatil e than gasoline , smal l amount s ma

y escap e t o th e atmospher e b y evaporatio n fro

mfue l system s o r

storag e facilities . TE Lan dTM Lar e light-sensitiv e an dunderg o photochemical decompositio n whe n they reac hth e atmosphere. 101 9 

### Th e lifetime o f TM Lappear s t o b e longer than tha t o f TEL . Exposur e o

f dus t t o TEL , bot hi n th e presenc e andabsenc e o f water vapor , result s i n sorptio n o

f organi c leadon dus t

particl e surfaces. 2 0 

### Laveskog 2 1 

### foundthat transien t

pea k leadalky l concentration s up t o 500 0 fig lead/m 3 

### i n exhaus t ga s ma y b e reache di

n acold-started , fully choked , an dpoorl y tune dvehicle . I f avehicl e wit

h suchemission s wer

e t o pas s asamplin g statio n on a stree t where th e lea

dalky l level migh

t typicall y b e 0.0 2 t o 0.04 /ng/m 3 

### o f

air , apea k o f abou t 0. 5 /ug/m3 

### coul db e measure da s th e ca r passe dby . Th e dat are porte db y Lavesko g were obtaine dwit haprocedur e that collecte dver

y smal l (10 0 ml) , short-tim e (1 0 min ) ai r samples . Th e sensitivit

y reporte dwa s much bette r than that reporte db

y othe r investigators , who hav e no t been abl e t o duplicat e hi s results. 2 2 

### Har riso n e t al. 2 2 

### foundlevel s a s higha s 0.5 9 /xg/m3 

### (9. 7 percen t o f tota l lead ) at

abus y gasolin e servic e sta tion . Purdu e e t al. 2 3 

### measure dparticulat e an dorgani c leadi n atmospheri c samples . Som e result s ar e shown i n Table s 6- 2 throug h6-4 . Thes e dat ademonstrat e tha t i n al l o f th e citie s studied , particulat e leadlevel s ar e muchhigher

(a n averag e o

f approximatel y 2 0 6- 4P.6 9

time s higher ) tha n organi c lea dlevels . Th e result s ar e entirel y consisten t

wit hth e studie s o f

Huntzicke r e t al., 1 0 wh o repor t

a n organi c componen t o f 6 per cen t o f th e tota l airborn e lea din Pasaden afo r a3 - da y perio di n Jun e 1974 , an do f Skogerboe, 2 4 wh o measure dfraction s in th e rang e o f 4 t o 1 2 percen t

at asit e in For t

Collins , Colorado . I t

i s noteworthy , however , tha t

in th e undergroun dgarag e (Tabl e TABL E 6-2 . RESULT S O F ATMOSPHERI C SAMPLING 6-4) , tota l lea dconcentration s ar e approximatel y fiv e time s thos e in th e urba n areas , an dth e per centag e o f

organi c lea dincrease s t o approximatel y 1 7 percent . Consequently , th e concentratio n o f organi c lea di na n undergroun dgarag e sit e i s te n time s tha t

inth e ope nurba nenvironmen t (se e Ta ble s 6- 2 an d6-4) , an dth e potentia l exposur e leve l i s similarl y magnified . FO R ORGANI C AN D PARTICULAT E LEAD 23 ( M g/m 3 ) Sampl e no. a 1 2 3 4 5 6 7 8 9 1 0 Avg . Cincinnat i

Organi cParticulate 0 0. 2 0. 0 0. 0 0. 2 0. 4 0. 2 0. 2 0. 4 0. 2 0. 2 0. 2 1.

5 0. 9 0. 9 1. 9 3. 7 1. 6 1.8 1. 3 1. 5 2. 4 1. 7 De n

Organi c 0. 2 0.5 d 1.4 d 0. 3 0. 2 0. 1 0. 0 0. 2 0. 2 0.5 d 0. 2 ve r

Particulat e 2. 3 1. 8 1. 6 1. 7 1. 0 1. 8 2. 2 1. 8 2. 0 — 1. 8 Washington , D.C . Organi cParticulat e 0. 0 0. 2 0. 1 0. 3 0. 1 0. 1 0. 1 0. 2 0. 4 0. 2 0. 2 1.

4 1. 4 1. 5 1.0 1. 1 0. 8 1. 7 1. 2 0. 8 1. 6 1. 2 St .

Organi c 0. 5 0. 2 0. 4 0. 2 0. 3 0. 2 0. 3 0. 4 0. 4 1.3 d 0. 3 Loui s

Particulat e 2. 0 2. 0 1. 8 2. 5 1. 9 1. 8 2. 2 2. 2 2. 0 1. 2 2. 0 Philadelphi a

Organi cParticulat e 0. 5 1.1 d 0. 2 0. 4 0. 8 0. 4 0. 0 0. 3 0. 1 0. 1 0. 3 1.3

1. 7 2. 9 2. 4 1. 1 1. 1 1. 7 2. 1 1. 8 2. 3 1. 8 Ch i Organi c 0. 2 0. 4 0. 2 1.6 d 0. 2 0. 2 0. 3 0. 1 0. 2 0. 2 0. 2 :ag o

Particulat e 5. 9 5. 6 5. 3 3. 5 4. 6 5. 5 5. 8 4. 8 5. 0 5. 1 5. 1 Sampl e no . represent s orde ri n whic h sample s wer e taken . Citie s wer e no t sample d concurrently . Al l value s ar e averag e o t tw o determinations , determine d b yNAS N metho d (6) . Organi clea d average s d o no t includ e thes e value s becaus e th e replicat e value s to rthes e sample s wer e mor e tha n twic e th e standar d deviatio n fro m th e average . TABL E 6-3 . PERCENTAG E O F PARTICULAT E VERSU S VAPOR-PHAS E LEA D I N URBA N AI R SAMPLES 2 3

Cit y Cincinnat i Denve r Washington , D.C . St . Loui s Philadelphi a Chicag o a AI I value s ar e average s Tota l lead 3 Organic . ug/ m 0. 2 0. 2 0. 2 0. 3 0. 3 0. 2 o f te n determination s particulat e P b x Particulate ,

jig/m 3 1. 7 1. 8 1. 2 2. 0 1. 8 5. 1 to o Particulate .

% o f tota l 8 9 9 0 8 6 87 8 6 9 6

TABL E 6-4 . ANALYSE S O F FIV E REPLICAT E SAMPLE S TAKE N I N A N UNDERGROUN D PARKIN G GARAGE 2 3 Organi c lead , Sampl e no . /J.g/ m 1 1. 9 2 1. 9 3 1. 9 4 1. 8 5 2. 2 Averag e (X)

1. 9 Relativ e standar d deviatio n (Srel) a 7.9 % a 0 . Standar d deviatio n ,„ „ Sre l = x10 0 Organi c lead . % 15. 7 17. 1 17. 6 14. 9 18. 0 16. 7 7.9 % Particulat e

lead , /ig/m 3 10. 3 9. 2 8. 9 10. 3 10. 0 9. 7 6.7 % Tota l

lead . Mg/m 3 12. 2 11. 1 10. 8 12. 1 12. 2 11. 6 5.2 % Averag e A s th e lea dalky l compound s o f gasolin e ar e sub jecte dt o th e elevate dtemperature s an dpressur e o f combustion , the y ar e converte dt o lea doxides , whic hfunctio n t o inhibi t engin e knock . Th e lea dox ide s reac t

withothe r

additive s inth e fuel an dleav e th e combustio nchamber s in avariet y o f comple x compounds . Th e result s o f compositio nstudie s b y Hirschle r an dGilbert, 4 Te r

Haa r e t al., 2 an dTe r Haa r an dBayard 2 5 ar e show n in Table s 6- 5 an d6-6 , respectively . Habib i e t al. 5 determine dth e compositio n o f par ticulat e matte r

emitte dfro mates t

ca r operatin g o n a typica l drivin g cycle . Th e mai n conclusion s draw n fro mth e stud y were : 1 . Compositio n o f

emitte dexhaus t

particle s i s relate dt o particl e size . 2 . Ver y larg e particle s greate r tha n20 0 fim hav e acompositio n simila r t o lead-contain in g materia l deposite dinth e exhaus t system , confirmin g tha t

the y hav e bee nre-entraine d o r hav e flake dof

f fro mth e exhaus t

system . Thes e particle s contai n approximatel y 6 0 t o 6 5 percen t

lea dsalts , 3 0 t o 3 5 percen t ferri c oxid e (Fe 2 0 3 ) , an d2 t o 3 percen t soo t an d carbonaceou s material . Th e majo r lea dsal t i s lea dbromochlorid e (PbBrCl) , wit hlarg e amount s (1 5 t o 1 7 percent ) o f lea doxid e 6- 5P.7 0

TABL E 6-5 . AVERAG E COMPOSITIO N O F PARTICULAT E LEA D COMPOUND S EMITTE D I N AUT O EXHAUST 8 ' 2 ' 4 Compound , wt . % aNH„CI - /3NH 4 CI - 2NH 4 CI - 3Pb 3 (P0 4 lj " Exhaus t sourc e PbCIB r2PbCIB r2PbCiB rPbCIB r"bCIB r CarB : Cit ytyp e cycle , fue l plu s TE L moto rmi xonl y6 8 2 4 6 2 — Cit ytyp e cycle , adde d sultur c7 0 3 0 ——— Cit ytyp e cycle , adde d phosphorus d 3 5 1 8 1 7 1 0 2 0 Constan t speed , 6 0 mph , roa d loa d 6 0 2 0 2 0 —— Full-throttl e acceleration s 8 5 1 0 5 — - — CarM : Cit ytyp e cycle , fue l plu s TE L moto rmi xonl y3 3 4 0 5 2 2 — Constan t speed , 6 0 mph , roa d loa d 3 0 3 0 3 5 5 — Full-throttl e acceleration s 9 0 1 0 ——— a X-ra ydiffractio n analyse s mad e in situ o n materia l deposite d o n glas s slide s mounte d withi n th e precipitato rof th e sampler . I n additio n t o th e tabulate d compounds . PbSO . an d PbO-PbCI-Br-hL O occurre d ocasionall yi n concentration s o f 5 percen t o rless . c Sulfu rconten t increase d fro m 0.02 5 t o 0.10 5 weigh t percen t byadditio n o f disulfid e oil . 0. 4 theor yphosphoru s added . TABL E 6-6 . EFFECT S O F AGIN G O N LEA D COMPOUND S I N SAMPLE S O F AUT O EXHAUS TA S DETERMINE D B YELECTRO N MICROPROBE 2 5

Percentag e o f tota l particle s sample d Blac k bag 3 Eight-Mil e Road b Lea d compoun d Zer o tim e 1 8 hou rNea rroa d 40 0 y d Rura l site 0 PbCi ^ 10 4 8 3 iT 2 10 5 5~ 4 PbBr 2 5. 5 0. 5 4. 0 0. 7 0. 1 PbBrC I 32. 0 12. 0 4. 4 0. 6 1. 6 Pb(OH)C I 7. 7 7. 2 4. 6 8. 8 4. 0 Pb(OH)B r2. 2 0. 1 2. 0 1. 1 — (PbO) 2 PbCI 2 5. 2 5. 6 2. 8 5. 6 1.5 (PbO) 2 -PbBr 2 1. 1 0. 1 0. 7 0. 3 — (PbO) 2 PbBrC I 31. 4 1. 6 2. 0 0. 6 1. 0 PbC0 3 1.2 13. 8 15. 6 14. 6 30. 2 Pb 3 (P0 4 ) 2 ——0. 2 0. 3 — PbO x2. 2 21. 2 12. 0 25. 0 20. 5 (PbO) 2 PbC0 3 1. 0 29. 6 37. 9 21. 3 27. 5 PbOPbS0 4 —0. 1 1. 0 4. 6 5. 0 PbS0 4 0. 1 —2. 2 6. 0 3. 2 Sampl e collecte d directl yfro m tailpip e i n blac k ba g t o preven t irradiatio n o f exhaust . Analyze d immediatel yan d agai n 1 8 h rlate rt o determin e effec t o f aging . Stat e highwa yi n Detroi t carryin g abou t 100,00 0 car s a day . °Sample s wer e take n 40 0 y d fro m a lightl ytravele d roadway . 

### (PbO ) occurrin g a s th e 2 PbC^PbBrC l dou - b y X-ray diffraction . Thi s i s particularl y bl e salt . Leadsulfate an dleadphosphat e ac - tru e fo r particle s i

n th e 2 - t o 0.5-micromete r coun t fo r 5 t o 6 percen t

o f thes e deposits . siz e range . (Thes e composition s resulte dfro mth e com - 6 . Ther e i s considerabl y more soo t andcar bustio n o f low-sulfur

an dlow-phosphoru s bonaceou s material associate dwit hsmal l fuel. ) particle s tha n wit hcoars e particle s re 3 . PbBrC I i s th e major

leadsal t i n particle s of

2 entraine dafte r havin g been deposite dafte r t o 1 0 micrometer s equivalen t diameter , wit

hemissio n fro

mth e exhaus t

system . Thi s car 2 PbBrC I -NH4 

### C 1 present a s amino r

constit - bonaceou s material account s fo r 1 5 t o 2 0 uent . percen t o f th e fine r particles . 4 . Submicrometer-size dlea dsalt s ar e pri - 7 . Particulat e matte r emitte dunder

typical maril y 2PbBrCl-NH 4 

### Cl . drivin g condition s i s ric hi n carbonaceous 5 . Lead-haloge n mola

r ratio s i n particle s o

f typ e material . Ther e i s substantiall y les s such les s than 1 0 micron s MME D indicat e tha t materia l emitte dunde r continuou s ho t muchmor e haloge n i s associate dwit hthes e operation . solid s than th e amount

expecte dfro

mth e 8 . Onl y smal l quantitie s o f 2PbBrCl«NH 4 

### C I presenc e o

f 2PbBrCl»NH 4 

### Cl , a s identifie dwere foundi n sample s collecte da

t th e tail 6- 6P.7 1

pip e fro mth e ho t

exhaus t gas . It s formatio n therefor e take s plac e primaril y durin g cool in g an dmixin g o f

exhaus t withambien t

air . Hirschle r an dGilbert 4 foun dsimila r result s an d speculate dtha t

highe r ga s temperatur e durin g full throttl e operation s reduce dth e tendenc y fo r th e am monium-lea dhalid e complexe s t o b e presen t sinc e the y ar e unstabl e at

hig htemperatures . Base do n th e abov e studies , it seem s quit e clea r tha t th e size.distributio n o f lea dparticle s emitte d fro mautomobile s an dth e relativ e concentration s o f th e comple x compound s in thos e particle s var y sig nificantl y wit hdrivin g conditions , engin e condition , typ e o f fuel , an dag e o f

exhaus t system . Particle s > 2 fim in th e exhauste dparticulat e ar e primaril y lea d bromochloride . Th e ver y larg e particles , aconse quenc e o f

deposit s in th e exhaus t system , ar e als o primaril y lea dbromochloride . Th e fate s o f

thes e lea dcompounds , onc e the y ar e introduce dint o th e atmospher e fro mautomobiles , ar e no t completel y understood . Ther e i s disagree men t in th e earl y literatur e concernin g th e los s o f halogen s b y thes e lea dcompounds . Pierrard 2 6 sug geste dtha t

PbBrC I undergoe s photochemica l decompositio n withth e formatio n o f alea doxid e an dth e releas e o f

fre e bromin e an dchlorine , bu t late r suggeste dahydrolyti c conversio n mechanism . Te r Haa r an dBayard 2 5 an dRobbin s an dSnitz 2 7 confir mth e los s o f

haloge n fro mfreshl y emitte dP b salts , bu t the y d o no t

suppor t th e photochemica l mechanism . Te r

Haa r an dBayard 2 5 sugges t tha t lea dhalide s ar e eventuall y converte dt o lea dcar bonate s an dlea doxides . Pierrard 26 obtaine ddat ao n age dlea daeroso l tha t

indicate dtha t

th e lea dparti cl e surface s ha dalread y bee n converte dt o a relativel y insolubl e formsuc ha s oxide , carbonate , o r basi c halide ; thi s woul db e consisten t wit hacon versio n mechanis mexpecte dt o releas e th e les s reac tiv e hydroge n halid e rathe r tha n th e mor e reactiv e molecula r

halogen . Dzuba y an dStevens 2 8 observe d adiurna l variato n in th e bromine-to-lea dcon centratio n rati o in atmospheri c particulat e indica tiv e o f th e los s o f

halogen s durin g atmospheri c transport . Te r

Haa r an dBayard 2 5 studie dth e effect s o f agin g o n automobil e exhaus t collecte din ablac k bag , usin g an electro n probe . Th e results , show ni n Tabl e 6-6 , indicat e tha t 7 5 percen t

o f th e bromin e an d3 0 t o 4 0 percen t

o f th e chlorin e associate dwith th e compound s containe din th e particulate s wer e los t in 1 8 hr ; dat apresente dsugges t tha t th e pro portion s o f

lea dcarbonate s an alea doxide s in creased . Sinc e thes e chemica l reaction s occurre din a blac k bag , photolyti c processe s woul dno t likel y b e responsibl e fo r th e decreas e inhalides . A t th e ver y least , therefore , thi s experimen t demonstrate s th e existenc e o f

nonphotolyti c decompositio npathway s fo r lea dhalide s in th e atmosphere . Consequently , th e chemica l compositio n o f lea dinth e atmospher e fro mautomobil e emission s almos t certainl y depend s t o som e exten t

o n th e ag e o f

th e particle s a s wel l a s th e presenc e o f

othe r pollutant s withwhic hth e lea d compound s ca n react . Th e result s o f

Le e e t al. 9 sho w tha t

th e percentag e o f water-solubl e particulat e lea dincrease dwhe n dilute dexhaus t

wa s irradiate db y ligh t in th e wave lengt hregio no f

300 0 t o 600 0 A . Thi s regio n i s in th e near-ultraviole t

an dvisibl e region s o f

th e spectru m an di s availabl e fro mdirec t sunlight . Th e percentag e o f water-solubl e lea dinth e dilute dexhaus t als o wa s increase db y irradiatio n inth e presenc e o f 0. 5 pp m S0 2 . Irradiatio n significantl y increase dth e sulfat e concentratio no f

th e particulate s an dwa s accom panie db y ashif

t t o smalle r

particl e sizes . A shif

t o f nitrate-bearin g particle s t o smalle r sizes , wit han d withou t additio n o f

S0 2 , wa s als o observe dwithir radiation . Th e amoun t o f nitrat e presen t

wa s decrease din th e presenc e o f S0 2 . Th e lea dnitrate , whic hi s muc hmor e solubl e in wate r tha n th e othe r lea dsalt s present , canno t b e totall y responsibl e fo r th e increase dwate r

solubilit y observe di

f th e N0 3 concentration s decrease . Th e informatio navailabl e regardin g th e chemica l compositio no f

lea dparticle s emitte dfro mauto mobile s ma y b e summarize da s follows : 1 . Lea dhaloge ncompound s ar e th e principa l form s emitted ; lea dchlorobromid e i s th e mos t prominen t

o f these . 2 . Th e particulate s underg o compositiona l change s durin g transpor t awa y fro mth e source . Thes e change s appea r t o consistentl y involve : a . Losse s o f

halogens , th e rat e o f

whic hmigh t b e photochemicall y enhanced , bu t whic h als o occu r

in th e absenc e o f

light . b . Genera l increase s i n th e wate r solubilitie s o f th e particle s wit hconcomitan t shift s towar dsmalle r

mea n particl e sizes . Thes e latte r change s ar e enhance db y th e pres enc e o f SO z , in whic hcas e th e amount s o f nitrat e presen t

decrease . 3 . Althoug hsevera l report s hav e suggeste dtha t th e lea dhaloge ncompound s ar e converte d t o oxide s and/o r

carbonates , th e onl y specifi c examinatio no f

th e compositio nafte r

agin g wa s tha t o f Te r Haa r an dBayard. 2 5 Unfor tunately , thei r

experimenta l approac hdi d 6- 7P.7 2

no t rel y o n aparticularl y definitiv e metho d o f identification . Indeed , th e electro n micro prob e approac huse dca n onl y b e regarde da s acrud e qualitativ e too l fo r th e identificatio n o f compounds ; th e simultaneou s occurrence s o f othe r element s in lead-bearin g particle s an dth e genera l morphologica l charac teristic s o f

th e particle s ca n provid e onl y cir cumstantia l indication s o f th e compound s tha t ar e present . Thi s i s particularl y tru e fo r lead-bearin g particle s becaus e compound s o f severa l othe r

element s ar e als o typicall y pre sent . Habib i e t

al., 5 fo r example , hav e show n tha t th e particle s ofte n includ e iro n a s wel l a s lea dcompounds . Th e percentag e composi tio n dat agive n in Tabl e 6- 6 shoul dals o b e evaluated , takin g int o accoun t tha t the y ar e numbe r rathe r tha n mas s percentages . Thus , althoug hlea dcarbonate , fo r example , ma y compris e arelativel y hig hnumbe r percen tag e o f th e total , it s mas s percentag e ma y b e quit e different , dependin g o n th e siz e distri bution s involve dan dwhethe r th e particl e composition s ar e siz e dependent . Thes e genera l conclusion s an dqualification s ar e consisten t

withan dsupportiv e o f th e result s o f

th e stud y reporte db y Olso n an dSkogerboe. 2 9 The y determine dtha t

th e principa l formo f

lea dfoun din lead-contaminate dsoil s fro mhighwa y median s a s wel l a s in stree t

dust s wa s lea dsulfate . Althoug hthi s stud y include devaluatio n o f 1 8 soi l and/o r

dus t sample s collecte dfro mdifferen t U.S . locations , sig nifican t amount s o f

th e lea dhaloge n compound s wer e foun din an y case . Th e conversio n o f lea d halide s t o othe r

compound s appear s t o hav e bee n quit e complet e fo r

thes e age dlea daeroso l deposits . 6.2.2. 2 STATIONAR Y SOURC EEMISSION S Measurement s ar e no t

availabl e t o confir mth e chemica l for mo f

lea demission s fro mstationar y sources . Barltro p an dMeek 3 0 indicat e th e presence , withou t referenc e t o specifi c measurements , o f lea d sulfid e o r

lea dchlorid e i n th e minin g industry , lea d oxid e in smelters , an dlea dcarbonat e an dlea dchro mat e in pigment s use din olde r paints . Lea doxid e i s th e principa l formo f

th e meta l use din batter y manufacturing . Th e associatio n o f

lea dsulfid e wit hminin g i s clearl y rational , sinc e thi s i s th e primar y minera l for m(galena) . Whil e lea doxid e ma y certainl y b e derive dfro mth e smeltin g process , th e amount s pro duce dma y b e relativel y smal l in compariso nt o th e amount s o f

lea dsulfid e release da s fugitiv e dus t t o th e atmospher e aroun dasmelter . Moreover , th e releas e o f

S0 2 usuall y associate dwithlea dsmeltin g operations , couple dwithth e possibl e interaction s betwee n lea dparticle s an dSO z , impl y tha t th e com pound s release dmay wel l underg o conversio n t o othe r forms . Thus , althoug hth e compound s generall y associate dwit hstationar y source s ar e no t particularl y soluble , th e possibilit y o f conversio n t o mor e solubl e compound s o r accumulatio n o f

th e particle s inth e lung s o f expose dpopulation s shoul d no t b e ignored . 6. 3 TRANSPOR T I N AI R Th e mechanism s o f

atmospheri c transport , removal , an dresuspensio n o f lea dparticulate s in terac t in acomple x manner . Th e transpor t mechan ism s ar e function s o f

th e particl e siz e distribution , particl e morphology , meteorology , an dloca l topography . 6.3. 1 Distributio n Mechanism s Th e transpor t

an ddiffusio n o f

gaseou s an dpartic ulat e material s inth e atmospher e ar e consequence s o f molecula r

diffusio nan dth e three-dimensiona l motio nfield , th e latte r

bein g th e dominan t

factor . A detaile dtreatmen t

o f thes e phenomen awill b e foun d inman y standar dtextbook s o nmeteorology . Th e three-dimensiona l motio nfiel dca nb e assume dt o b e compose do f

amea n win d(transport ) vecto r an da turbulen t component . Th e turbulen t componen t

i s analogou s t o molecula r

diffusion , bu t

th e coefficien t o f turbulen t

edd y diffusio n i s usuall y o f muc h greate r magnitude . Th e turbulen t componen t

tend s t o sprea dth e materia l verticall y an dlaterall y abou t th e mea nhorizonta l transpor t vector . Therefore , assumin g apollutio n plum e fro maloca l lin e o r poin t source , th e atmospheri c motio nserve s t o dilut e an dtranspor t

th e pollutants . Sinc e lea demitte dt o th e atmospher e i s primaril y inth e inorgani c particulat e form , it s transpor t an d dispersio n will depen dprimaril y o n particl e siz e a s wel l a s chemica l stability , th e heigh t o f injection , an dth e intensit y an dstabilit y o f th e atmospheri c motio nfield . Larg e particle s injecte da t lo w eleva tion s wil l settl e t o th e surfac e inth e immediat e vicinit y o f

th e source , wherea s th e smalle r particle s wil l b e transporte dove r greate r distances . A stud y b y Daine s e t

al. 3 1 relate datmospheri c lea dt o traffi c volum e an ddistanc e fro mahighway . The y foun dth e effec t

o f traffi c o nlea dconten t

o f th e ai r t o b e striking , bu t

limite dt o arathe r

narro w zon e borderin g primaril y th e le e sid e o f th e highway , a s show nin Figur e 6-7 . Abou t 6 5 percen t

o f th e lea din 6- 8th e ai r

betwee n 3 0 an d175 0 f t fro mth e highwa y consiste do f

particle s unde r

2 fim, an d8 5 percen t wer e unde r

4 fim in diameter . Figur e 6- 8 show s a typica l relationshi p o f

particl e siz e t o distanc e fro m th e highway . Chola k

etal. 1 2 an dSchuc k

an dLocke 3 2 di dsimila r

studie s wit hsimila r

results . A s show n in Figure s 6- 4 an d6-5 , Huntzicke r e t al. 1 0 demon strate dtha t

th e larg e particl e mod e (D p > 7 fim) in th e freewa y distributio n i s severl y attenuate dat th e Pasaden asite . 0 I 1 1 I

-

-

- TRAFFI C VOLUME , vehicles/da y 1 0 - 58,00 0 \ 6 - 47.00 0 ft •- 44,00 0 \ O - 19,80 0 

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—o 1 20 0 30 0 40 0 DISTANC E FRO M HIGHWAY , fee t Figur e 6-7 . Air-lea d value s a s a functio n o f traffi c volum e an d distanc e fro m th e highway. 3 1

% HAVIN G MEA N MAS S DIAMETE R LES S THA N Figur e 6-8 . Relationshi p o f th e diamete r o

f th e particle s (mass ) t o distanc e fro m th e highway. 3 1 Knowledg e o f

lea dconcentration s in th e ocean s an dglacier s provide s som e insigh t int o th e degree s o f atmospheri c mixin g an dlong-rang e transport . Tatsumato , Patterson , an dChow 333 5 measure ddis solve dlea dconcentration s in se awate r of f th e coas t o f California , in th e Centra l Nort hAtlanti c (nea r Bermuda) , an din th e Mediterranean . Th e profile s obtaine dar e show n in Figur e 6-9 . Surfac e con centration s inth e Pacifi c wer e foun dt o b e highe r tha nthos e o f

th e Mediterranea n o r

th e Atlantic , an d decrease dabruptl y t o relativel y constan t level s wit h depth . Th e vertica l gradien t wa s foun dt o b e muc h les s inth e Atlantic . Base do n th e Pacifi c data , Tatsumat o an dPatterson 3 3 estimate da n averag e surfac e lea dconcentratio n o f 0. 2 /ig/k g in th e north er n hemispheri c oceans . Cho w an dPatterson 3 5 revise dthi s estimat e downwar dt o 0.0 7 figlkg. Ther e appear s t o b e n o differenc e betwee nlea dconcentra tion s in dee p wate r

inth e Atlanti c an dPacific . Thes e investigator s calculate dtha t industria l lea di s cur rentl y bein g adde dt o th e ocean s a t abou t 1 0 time s th e rat e o f

introductio n b y natura l weathering , with significan t

amount s bein g remove dfro mth e at mospher e b y precipitatio nan ddeposite ddirectl y int o th e ocean . Thei r

dat asugges t

considerabl e con taminatio n o f

surfac e water s nea r

shore , diminishin g towar dth e ope nocean. 3 5 Thes e investigator s con clud e tha t

lea demission s fro mautomobile s ar e th e primar y sourc e o f

pollutio n o f

ocea nsurfac e water . 0

100 0

20OO

300 0

400 0 -1 —< r

i f f i I t

6

i o — 1

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O - ATLANTI C (BERMUDA ) O - MEDITERRANEA N 40°39'N , 05°48' E d- PACIFI C 29°13'N , 117°37' W I -

—

LEA D I N SE A WATER , vg/k g Figur e 6-9 . Lea d concentratio n profile s i n th e oceans . " ^ Duce , Taylor , Zoller , an dthei r co-workers 36 ' 3 8 hav e investigate dtrace-meta l concentration s (in cludin g lead ) inth e atmospher e inremot e norther n an dsouther nhemispheri c sites . Th e natura l source s fo r suc hatmospheri c trac e metal s includ e th e ocean s an dth e weatherin g o f

th e earth' s crust , wherea s th e manmad e sourc e i s particulat e pollution . Enrich men t factor s fo r

concentration s relativ e t o standar d value s fo r

th e ocean s an dth e crus t wer e calculate d (Tabl e 6-7) ; th e mea n crusta l enrichmen t factor s fo r th e Nort hAtlanti c an dth e Sout hPol e ar e show n in Figure s 6-1 0 an d6-11 . Th e significanc e o f th e com 6- 9P.7 4

pariso n in Figur e 6-1 1 i s tha t 9 0 percen t

o f th e par ticulat e pollutant s in th e globa l tropospher e ar e in jecte din th e norther n hemisphere. 3 9 Sinc e th e resi denc e time s fo r

particle s in th e troposphere 4 0 ar e muc hles s tha n th e interhemispheri c mixin g time , it i s unlikel y tha t

significan t

amount s o f

particulat e pollutant s ca n migrat e fro mth e Nort hAtlanti c t o Antarctic avi ath e troposphere ; howeve r thi s doe s no t rul e ou t

stratospheri c transfer . I n th e cas e o f lea d(an dal l othe r

metal s studie dexcep t

vanadium) , th e enrichmen t

factor s wer e ver y simila r at th e tw o locations . Thi s suggest s (bu t doe s no t prove ) tha t

th e atmospheri c concentration s o f thes e metal s ma y originat e primaril y fro mnatura l (rathe r tha nman made ) sources . TABL E 6-7 . CONCENTRATIO N RANG E AN D MEA N EF cru8 t VALUE S FO R ATMOSPHERI C TRAC E METAL S COLLECTE D

OVE R TH E ATLANTI C NORT H O F 30 ° N 3 6

Concentralio n range , ng'sc m t r crust . qeom . mean 3 A l S e F e C o M n C r V Z n C u C d P b S b S e 8-37 0 0.0008-0.01 1 3.4-22 0 0.006-0.0 9 0.05-5. 4 0.07-1. 1 0.06-1 4 0.3-2 7 0.12-1 0 0.003-0.6 2 0.10-6 4 0.05-0.6 4 0.09-0.4 0 1. 0 0. 8 1. 4 2. 4 2. 6 1 1 1 7 11 0 12 0 73 0 2,20 0 2,30 0 10,00 0 Calculate d o n th e basi s o f th e mea n crusta l abundance s o f Taylor. "

Figur e 6-10 . Midpoin t collectio n locatio n fo r atmospheri c sample s collecte d fro m R . V . Trfden f nort h o f 30°N , 197 0 throug h 1972. 36 ' 3 8 Murozum i e t

al. 4 1 hav e presente dsupportiv e evi dence . Thei r

dat asho w tha t

long-rang e transpor t

o f lea daerosol s emitte dfro mautomobile s ha s signifi cantl y pollute dth e pola r glaciers . The y collecte d •NORT H ATLANTI C WESTERLIE S D SOUT H POL E



### CogivTB " 

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Figur e 6-11 . Th e EF crug t value s fo r atmospheri c trac e metal s collecte d i n th e Nort h Atlanti c westerlie s an d a t th e Sout h Pole . Th e horizonta l bar s represen t th e geometri c mea n enrichmen t factors , an d th e vertica l bar s represen t th e geometri c standar d deviatio n o f th e mea n enrichmen t fac tors . Th e EF crus t fo r lea d a t th e Sout h Pol e i s base d o n th e lowes t lea d concentratio n (0. 2 mg/scm). 36 ' 3 8 sample s o f

sno w an dic e fro mGreenlan dan dth e Antarctic . A s show ninFigur e 6-12 , the y foun dtha t th e concentratio n o f

lea dvarie dinversel y withth e geologica l ag e o f

th e sample . Th e author s attribut e th e gradien t

increas e afte r

175 0 t o th e Industria l Revolutio n an dth e enhance dincreas e afte r 194 0 t o th e increase dus e o f

lea dalkyl s ingasoline . Th e mos t recen t level s froun din th e antarcti c snow s were , however , les s tha n thos e foun din Greenlan d b y afacto r

o f 1 0 o r more . Befor e 1940 , th e con centration s inth e Antarcti c wer e belo w th e detect abl e leve l ( < 0.00 1 /xg/kg ) an dhav e rise n t o 0. 2 Mg/k g in recen t

snow . A grap ho f

th e worl dlea d smelte r an dlea dalky l productio n presente db y Murozum i e t

al. 4 1 i s show n in Figur e 6-13 ; support in g dat aar e show ninTabl e 6-8 . Th e result s an dconclusion s o f Murozum i e t

al . wer e criticize db y Mills, 4 2 wh o suggeste dth e in creas e inth e sno w lea dafte r 194 0 coul db e du e t o aircraf t operatin g fro mThul e Ai r Forc e Base . Bryce-Smith 4 3 countere dMills ' argumen t b y statin g tha t th e greates t

amoun t

o f lea dfoun dt o b e deposite dinth e sno w wa s durin g winte r month s whe n ai r traffi c wa s lightest ; ther e wa s n o horizonta l gradien t betwee nth e ai r

bas e an dth e collectin g site ; th e collectin g sit e wa s predominantl y upwin dfro m th e ai r base ; and , finally , th e majo r increas e in lea d level s bega nabou t

2 0 year s befor e th e neares t operatin g bas e wa s established . Jaworowski 4 4 foun dtha t lea dconcentration s in tw o glacier s hav e increase db y afacto r o f 1 0 durin g th e las t century . Th e concentration s inth e mos t re 6-1 00.2 0 0.1 8 0.1 6 0.1 4 0.1 2 0.1 0 0.0 8 O.O E 0.0 4 0.0 2 n ' I T-TV " 1 1 1 1

J.iy , T l 1 1 1 , 1 1 1 1 |

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- O - LEA D SMELTE D I N NORTHER N HEMISPHER E D - LEA D SMELTE D I N SOUTHER N HEMISPHER E & - LEA D BURNE D A S ALKYL S I N NORTHER N HEMISPHER E

80 0 h«-B,C , »| « 180 0 185 0 A . D . AG E O F SAMPLE S Figur e 6-12 . Lea d concentratio n profil e i n sno wstrat a o

f Norther n Greenland. 4 1 Figur e 6-13 . Worl d lea d smelte r an d alky l lea d productio n sinc e 175 0 A.D. 4 1 TABL E 6-8 . LEA D AEROSO L PRODUCTIO N I N TH E NORTHER N HEMISPHER E COMPARE D WIT H LEA D CONCENTRATION S I N CAM P CENTURY , GREENLAND , SNO W A TDIFFEREN TTIMES 4 1

Dat e 1753 181 5 193 3 196 6 Lea d

smelted . 10 3 tons/y r 1 2 1 6 3 1 Fractio n

converte d t o aerosols . % 2 2 1 6 0.0 6 Lea d

aerosol s produce d fro m smelteries. . 10 3 tons'y r 2 4 8 2 Lea d burne d

as alkyls . 10 3 lons/y r — — 0- 1 3 Fractio n

converte d t o aerosols . % — — 4 0 4 0 Lea d

aerosol s produce d fro m alkyls . 10 3 tons/y r

• — — 4 10 0 Tota l lea d

aerosol s produced . 10 3 tons/y r 2 4 12 a 102 a Lea d

concentratio n at Cam p Century . /ig/k g sno w 0.0 1 0.03 0.07 0. 2 a Value s corrected . cen t ic e layer s wer e extremel y hig h(14 8 fig/kg). Jaworowsk i e t

al. 4 5 als o studie dstabl e an dradio activ e pollutant s fro mic e sample s fro mStorbree n glacier s in Norway . Th e mea n stabl e lea dconcentra tio n in Storbree n glacie r ic e in th e 12t

hcentur y wa s 2.1 3 figlkg. Th e mea n fo r mor e recen t

sample s wa s 9.8 8 /u.g/kg . Aroun d1870 , th e averag e lea dcon centratio n in Norwegia n glacie r ic e wa s 5.8 6 figlkg, wherea s tha t

fo r glacier s in Polan dwa s 5. 0 figlkg. A centur y later , th e mea n concentratio n in th e Nor wegia n glacie r

wa s 9.8 8 Mg/kg , wherea s th e mea n concentratio n in th e Polis hglacie r reache d14 8 Mg/kg . Jaworowsk i e t

al. 4 5 attribute dth e larg e in creas e o f lea dconcentration s in th e Polis hglacie r t o loca l sources . Jaworowsk i e t

al. 4 5 als o measure d2,0 P b inth e glacie r ice . Th e value s foun din th e Storbree nglacie r ic e ar e show n graphicall y in Figur e 6-14 . Th e high es t valu e wa s foun din 1961 . A simila r valu e wa s foun din Polis hglacier s an din th e Alp s th e sam e year. 4 4 Th e value s an dirregularitie s observe din ^ 10 P b concentration s in th e investigation s sugges t tha t par t o f th e atmospheri c 2l0 P b ma y hav e origi nate dfro martificia l source s —nuclea r explosion s inth e Arctic , o r

energ y productio nin fossil-fue l powe r stations . Base do nthei r findings , Jaworowsk i e t al. 4 5 conclude dtha t

long-rang e transpor t

o f lea d

YEAR . A S DETERMINE D B YDEPT H 196 6 6 5 6 4 6 3 6 2 6 1 6 0 5 9 5 8 5 7 5 6 5 S 5 4 4 0. 5 z 2 0. 4 H <-210CONCENToo

Q m 0. 1

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s Figur e 6-14 . 210 P b I n Storbreen , Norway , glacie r Ice , 1954-1966 , 4 5 6-1 1"*r*~ P.7 6

pollutant s in th e atmospher e i s areality , bu t th e author s sugges t

tha t th e rat e o f

contaminatio n o f glacie r ic e correlate s bette r

withth e tota l annua l in pu t o f coa l burnin g t o th e energ y syste mo f th e worl d tha n wit hlea demission s fro mautomobiles . 6.3. 2 Remova l Mechanism s Th e principa l mechanism s fo r remova l o f

in organi c lea dparticulat e fro mth e atmospher e ar e dr y depositio n an dprecipitation . Detaile ddis cussion s o f

thes e processe s will b e foun din standar d textbook s b y Sutton, 4 6 Pasquill, 4 7 Fletcher, 4 8 Junge, 4 9 Gree n an dLane, 5 0 an dSlade. 5 1 Th e remova l efficienc y o f

thes e processe s varie s signifi cantly , dependin g o n physica l characteristic s o f th e suspende dmaterial , atmospheri c conditions , an dth e natur e o f th e receivin g surface . 6.3.2. 1 DR Y DEPOSITIO N Dr y depositio n remova l processe s includ e sedi mentation , diffusion , an dinertia l mechanism s suc h a s impaction . Sedimentation , o r settlin g o f

particles , occur s whe n th e mas s o f th e particl e i s larg e enoug h t o overcom e th e buoyanc y forc e an dth e liftin g force s o f convectiv e currents . Freel y fallin g particle s o f th e siz e rang e foun din suspende daerosol s rapidl y attai n thei r

terminal , o r

constant , velocit y whe nth e aerodynami c dra g o n th e particl e i s equa l t o th e weigh t o f th e particle . Th e termina l velocit y depend s o n th e particl e size , it s density , an dgravitationa l ac celeration . Whe n aparticl e i s o f asiz e comparabl e t o th e mea n fre e pat hof

th e ga s molecules , bombard men t b y th e molecule s result s i n arando mo r Brownia n motio n tha t

i s superimpose do n it s down war dmotion . If

aparticl e i s ver y smal l an dit s mo tio n i s observe dfo r

onl y ashor t

perio do f

time , it s fal l ma y b e completel y maske db y th e Brownia nmo tion . Residenc e time s or , conversely , th e rat e o f fallou t o f aerosol s o r

dus t particle s containin g lea d in th e atmospher e ar e the n primaril y afunctio n o f particl e size . Th e shap e o f th e suspende dparticle s als o ha s asignifican t

effec t o n th e settlin g velocity . Usuall y th e settlin g velocit y o f particle s o f

variou s geometrica l form s i s calculate din term s o f th e set tlin g velocit y o f

spherica l particle s o f th e sam e volume . Th e aerodynami c particl e size , conven tionall y use dwhe n discussin g airborn e particulate , i s define da s th e siz e o f aspher e o f

uni t densit y tha t ha s identica l aerodynami c behavio r t o th e particl e in question . Particle s havin g th e sam e aerodynami c siz e may hav e differin g shape s an ddimensions . Airborn e particle s ar e generall y divide dint o thre e siz e ranges : Aitke n nucle i (particl e radiu s < 0. 1 fim), larg e nucle i (particl e radiu s 0. 1 t o 1 fim), an dgian t

nucle i (particl e radiu s > 1 fim). Ex tremel y smal l particle s (radiu s < 0.00 1 fim) ten dt o coagulat e rapidl y t o formlarge r ( ~ 0.0 5 t o 0. 5 fim), les s mobil e particles. 5 0 Fletcher 4 8 derive da n approximat e equatio nt o predic t th e rat e at

whic h th e concentratio nnumber , n , o f particle s o f

radius , r , wil l decreas e inarelativel y unifor maerosol . Fo r r = 0.00 5 /A

man dn = 10 5 /cm 3 (typica l in urba nair) , th e tim e require dfo r particl e concentratio n t o decreas e b y one-hal f

wa s calculate dt o b e 3 0 min . Fo r r = 0.\fimandn= 10 3 /cm 3 , 5 0 percen t reduc tio nwa s calculate dt o requir e 50 0 hr . Th e siz e dis tribution s o f

larg e an dgian t

nucle i ar e no t

signifi cantl y affecte db y coagulation . Settlin g o r

termina l velocitie s o f

spherical , parti cles , a s reporte db y Gree nan dLane 5 0 an dIsrae l an d Israe l , 5 2 ar e show n inTabl e 6-9 . TABL E 6-9 . TERMINA L VELOCITIE S O F SPHERICA L PARTICLE S O F UNI TDENSITYA TGROUN D LEVE L Particl e radius . /u n 0.0 1 0.05 0. 1 0. 2 0. 5 1.0 2. 0 5. 0 10. 0 20. 0 50. 0 Termina l velocit y

Israe l an d Israe l 1.4 3 x10" 5 — 2.32 X10 - 4 — — 1.3 2 x10" 2 — — 1.23x10 ° — — cm/se c

Gree n on d Lan e 8.7 1 x 10" 5 2.2 7 X10 - 4 6.85 x 10" 4 3.49 x10" 3 1.2 9 x10" 2 5.0 0 x10' 2 3.03 x10" 1 1.20x10 ° 4.7 1 24. 7 Airborn e particle s ar e als o remove dfro mth e at mospher e b y inertia l mechanisms . I nturbulen t iner tia l deposition , turbulen t win dfluctuation s per pendicula r

t o ahorizonta l surfac e impar t sufficien t inerti at o prope l th e particle s throug hth e boundar y laye r an dont o th e surface . Thi s mechanis mi s im portan t fo r bot hsmoot han droug hsurfaces . Whe n th e roughnes s element s o nasurfac e protrud e suffi cientl y fa

r int o th e windstream , inertia l impactio n ma y becom e important . Th e mea nhorizonta l flo w o f th e wind , rathe r

tha n turbulen t

fluctuations , con trol s impaction . Thi s mechanis moccur s whe nparti cle s canno t

follo w th e ai r

streamline s a s the y pas s aroun daroughnes s element . I n thi s case , th e mea n windflo w supplie s th e inerti atha t drive s th e parti cle s ont o th e surface . Inertia l mechanism s ar e dependen t o n at mospheri c condition s an dth e characteristic s o f th e surface . Th e small-scal e surfac e structur e ma y b e especiall y significant . Fo r example , smal l particle s 6-1 2ar e preferentiall y retaine do n lea f surfaces , wher e the y ma y b e tightl y retaine db y smal l hair s o nth e leaf , b y surfac e pores , an db y tack y substance s ex crete db y th e leaves . Impactio n o f submicrometer size dparticle s o n lea f

surface s i s possibl e at

norma l win dspeeds. 5 3 Pin e needle s an dsimilarl y shape d surface s appea r

t o b e aerodynamicall y attractiv e fo r impactio n o f

particulat e matter . Therefore , pin e tree s nea r

asurfac e sourc e o f

lea dparticulat e pollu tio n ma y increas e th e rat e at whic hlea daerosol s ar e remove dfro mth e atmosphere . Heiche l an d Hankin 5 4 reporte dsoi l lea dconcentration s in fron t o f an dwithi n aroadsid e windbrea k o f pin e tree s a s bein g 5 0 percen t

an d10 0 percen t

higher , respec tively , tha n soi l lea dconcentration s a t correspond in g distance s in anearb y ope n fiel dtha t bordere d th e sam e sid e o f

th e road . Particl e remova l rate s fro mth e atmospher e ar e usuall y describe din term s o f depositio nvelocity . Historically , depositio n velocitie s hav e bee ndefine d a s th e rati o o f

depositio n flu x t o th e airborn e con centratio n withunit s o f length/tim e usuall y reporte d a s cm/sec. 4 9 Sehme l an dHodgson 5 5 hav e publishe da mode l fo r

th e predictio n o f

dr y depositio nvelocitie s base do n thi s concept . K|_ 

### c (6-1 ) wher e K i s th e depositio n velocity , N i s th e deposi tio n flux , an dC i s th e airborn e concentratio nfo r monodisperse dparticle s measure d1 c mabov e th e depositio n surface . Th e depositio n velocity , K , assume s tha t

particl e depositio n i s describe db y a one-dimensional , steady-stat e continuit y equation . Th e basi c assumption s in th e mode l ar e tha t th e flu x i s constan t

withheight , tha t

arelationshi p fo r

parti cl e edd y diffusivity ca n b e determined , tha t th e effec t o f gravit y ca n b e describe db y th e termina l set tlin g velocity , tha t

agglomeratio n doe s no t occur , an dtha t particle s ar e completel y retaine do n th e surface . Th e mode l wa s designe dt o predic t deposi tio n velocitie s fo r

simpl e surfaces . Actua l remova l rate s ar e non-steady-stat e processe s dependen t o n th e deliver y capabilit y o f th e uppe r

atmospher e an d th e surfac e resistance . Base do n th e abov e assump tions , Sehme l an dHodgson 5 5 writ e th e equatio n fo r depositio n flu x as :

N = -( e + D ) —-v. C (6-2 )

d z wher e v t i s th e absolut e valu e o f th e termina l settlin g velocity , €

i s th e particl e edd y diffusivity , D i s th e Brownia n diffusivity , C i s th e airborn e concentra tion , an dz i s th e referenc e height . Fo r smal l parti cles , th e sedimentatio n ter m(-v,C ) i s negligibl e s o

tha t depositio n velocit y i s afunctio n o f th e Brown ianan dedd y diffusivit y ter monly . Fo r larg e parti cles , th e diffusivity ter mi s negligible , an dth e depositio n velocit y i s equa l t o th e termina l velocity . Incorporatin g th e concept s o f frictio nvelocity : 

### u. = 

### -^—L —(6-3 ) Klm(z/z 0 ) wher e k i s vo n Karman' s constant , u i s th e windspeed , z i s height , an dz o i s th e roughnes s height . Roughnes s heigh t i s define da s ameasur e o f th e roughnes s o f

asurfac e ove r

whic hflui di s flow ing : z o=H/3 0 (6 . 4 ) wher e H i s th e averag e heigh t o f surfac e ir regularities . Sehme l an dHodgson 5 5 develope dpre dictio n depositio n velocit y curve s fo r arang e o f roughnes s height s an dfrictio n velocities . Represen tativ e curve s ar e show n inFigure s 6-1 5 throug h 6-17 . Depositio nvelocitie s ar e show nt o b e afunc tio no f particl e diamete r

an dhav e thei r

smalles t value s in th e 0. 1 t o 1 fim particl e diamete r range . Th e mea n diamete r

o f lead-containin g particle s in th e atmosphere , remot e fro mmajo r sources , fall s ap proximatel y inthi s range . I nth e cas e o f large r parti cles , bot hincrease deffectiv e edd y diffusio n in sur fac e boundar y laye r

(a s aresul t

o f greate r particl e inertia ) an dincrease dgravitationa l settlin g rate s ten dt o increas e th e predicte ddepositio n velocitie s abov e th e minimum . Th e lowe r limi t o f th e pre dicte ddepositio n velocitie s i s th e sedimentatio n velocity . Fo r

smalle r particles , depositio n velocitie s increas e withdecreasin g particl e diameter s becaus e o f increase dmas s transfe r b y Brownia n motion . Depositio nvelocitie s fo r 0.01-M mparticle s ar e relativel y insensitiv e t o change s inparticl e diamete r a t elevate dheight s abov e 1 0 cm . Depositio n velocitie s at

1 c mabov e th e groun dar e extremel y large ; consequently , inth e 0.01-M mparticle diamete r range , th e depositio nvelocitie s ar e con trolle db y atmospheri c diffusio nin th e layer s im mediatel y abov e th e canopy . A s indicate db y Sehme l an dHodgson, 5 5 th e mode l shoul dpredic t reasona bl y wel l th e depositio n velocitie s fo r simpl e surfaces , assumin g th e win ddirectio n i s persisten t ove r suffi cien t distance . I t

shoul dnot , however , b e expecte d t o predic t

depositio nvelocitie s fo r acit y becaus e o f th e complexit y in th e geometr y o f th e surfac e an d becaus e o f

loca l win dconditions . Value s o f

lea ddepositio n velocitie s foun din th e literatur e generall y rang e fro mabou t 0. 1 t o 0. 5 cm/sec. 5 6 Thes e value s ar e base do ntota l lea dflu x an dtota l airborn e concentrations , withou t regar dt o 6-1 3P.7 8

particl e size . Sinc e larg e particle s ma y contro l lea d depositio n in certai n cases , i t i s necessar y t o examin e th e entir e siz e distributio n o f particle s i n orde r

t o calculat e depositio n rates . Further , accurat e isokineti c measurement s o f larg e airborn e particle s ar e require dt o relat e airborn e concentration s t o deposition . Davidson 5 6 foun dadepositio n velocit y o f 0.2 9 cm/se c i n Pasadena , base do n tota l flu x an d tota l airborn e concentrations . Base do n th e fractio n o f lea dparticle s greate r

tha n 1 0 microns , however , th e depositio n velocit y wa s 1. 3 cm/sec . Huntzicke r e t al. 10 foun dadepositio n velocit y o f 1.8 0 cm/se c o n aTeflo n plat e place do n th e shoulde r o f aLo s Angele s freeway .

£ 1 0 E * >ELOCOSITIONV

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10' ' 1 1 0 PARTICL E DIAMETER , micrometer s Figur e 6-15 . Predicte d depositio n velocity o f particle s a t indi cate d heigh t fo r u . = 2 0 cm/se c an d Z Q = 3. 0 cm. 5 5

— I 1 I I Mil l I— I I I I I M | I I I I 11I I | I—Illl l .UNSTABLE , L =-1 0 meter s

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1 0 1 1 0 PARTICL E DIAMETER , micrometer s Figur e 6-16 . Predicte d depositio n velocitie s o f particle s a t 1- m heigh t fo r z 0 = 3. 0 cm , 5 5 Johnson 5 7 sample dparticle s wit han instrumente d aircraf t flyin g a t

30 0 maltitud e i n th e vicint y o f St . Louis , Missouri . Particle s wer e collecte db y expos in g asmal l (1.0 - b y 7.5-cm ) glas s slid e covere dwith athi n laye r

o f high-viscosit y silicon e oi l t o th e fre e ai r strea moutsid e th e ski n o f th e aircraft . Particle s wer e counte dan dsize dmanuall y fro mphotographs . Sample s wer e obtaine dupwin dan ddownwin do f St . I I I I Illl l 1— I I I I lll | ^UNSTABLE , L » -1 0 meter s „STABLE,L "

I I I Illl l 1 0 1 1 0 PARTICL E DIAMETER , micrometer s 1 0 Figur e 6-17 . Predicte d depositio n velocitie s o fparticle s a t 1 m fo r u . = 20 0 cm/sec. 5 5 Loui s o n eac ho f

1 1 day s durin g th e perio dJul y l throug hJul y 18 , 1975 . Th e result s indicate dtypica l numbe r concentration s o f

airborn e particle s large r tha n 1 0 fim in diamete r o f 7,50 0 particles/m 3 up win dan d11,00 0 particles/m 3 downwind . Particle s large r tha n 3 0 fim in diamete r wer e foun din con centration s o f

20 0 particles/m 3 upwin dan d42 5 par ticles/m 3 downwin do f th e city . Fo r

th e downwin d particl e numbe r

densitie s o f

> 1 0 M man d>3 0 M

m particles , an dwit hth e assume ddensit y o f 2 g/m 3 , th e mas s concentration s woul db e abou t 0.0 1 ng/m 3 an d 0.01 2 ng/m 3 , respectively . Th e result s reporte dindi cat e tha t particle s >3 0 fim ca n b e transporte dt o altitude s o f

30 0 mb y convectiv e currents ; therefore , al l larg e particle s ar e no t remove db y sedimentatio n in th e immediat e vicinit y o f sources . Assumin g a sedimentatio nvelocit y o f 0. 3 cm/se c fo r

a1 0 fimdiamete r particl e an da n initia l heigh t o f 30 0 m , th e particl e coul dremai nairborn e fo r approximatel y 2 7 h r an db e transporte dabou t 20 0 k mwithaunifor m win do f 2 m/sec . Thi s typ e o f

lon g distanc e transpor t ha s bee n observe db y Gillett e an dWinchester 1 5 ove r Lak e Michigan . Th e actua l concentration s observe d ar e ver y small , however , an dwoul dcontribut e littl e t o ambien t

ai r loadin g o r

dustfal l accumulatio nin region s remot e fro mth e source . Lynam 5 8 studie dth e atmospheri c diffusio n o f car bo n monoxid e an dlea dfro ma n expresswa y (1-75 , nort ho f Cincinnati , Ohio) . Th e significan t result s ar e show n i n Figure s 6-1 8 throug h6-20 . Approx imatel y 5 0 percen t

o f th e lea demitte dfro mth e auto mobil e traffi c wa s remove dfro mth e atmospher e b y 6-1 4dr y depositio n withi n 64 0 f t o f th e edg e o f

th e road way (Figur e 6-18) . Th e siz e distributio n o f th e lea d particle s wa s no t

significantl y altere dbetwee n 2 0 an d64 0 f

t (~ 6 an d—19 5 meters) . Win dspeed s range dfro mapproximatel y 0. 5 t o 3. 8 m/sec . Assum in g amea n win dspee do f 2 m/sec , th e 50-percen t reductio n withi n 64 0 f

t woul dcorrespon dt o abou t 1. 5 mi n o f

trave l time . Th e concentratio n o f lea d decrease dfro mabou t

7 Mg/m 3 at

2 0 f t t o abou t 1. 5 Mg/m 3 a t 64 0 ft , adecreas e b y afacto r o f abou t 5 . Th e dat awer e no t

sufficien t

t o determin e th e rela tiv e efficienc y o f

sedimentatio n versu s impactio nin th e tota l remova l process ; however , Figure s 6-1 9 an d6-2 0 indicat e tha t

th e remova l mechanis mwa s no t strictl y limite dt o sedimentation . Daine s e t al., 3 1 in thei r stud y o f th e relationshi p o f

atmospheri c lea d t o traffi c volum e an ddistanc e fro mahighway , foun da50-percen t

reductio n in lea dbetwee n 1 0 an d 15 0 f t o f th e edg e o f

th e roadway . 1— I Illl l % LEA D REMOVE D =

_R = 0.6 8 

### i

—r i i 1 1

i IIII I 4 0 6 0 8 0 10 0 15 0 20 0 40 0 60 0

TRAVE L DISTANCE , fee t Figur e 6-18 . Regressio n o f percentag e lea d particulate s remove d b

y dry depositio n wit h distanc e fro m roadway. 6 8 (Legend:— = regressio n line;— = 95 % confidenc e limit s fo r regressio n line ; = 95 % confidenc e limit s fo r singl e value ; R = correlatio n coefficient. ) Smith 5 9 investigate dlea dcontaminatio n o f whit e pin e growin g alon g a n east-wes t sectio n o f

Interstat e 9 5 in Connecticut . H e foun dtha t lea dcontamina tio n decrease dregularl y withincreasin g distanc e fro mth e roa dan dwa s greates t o n th e side s o f

th e tree s neares t

th e highway . Base do n th e muc hhighe r concentratio n o f

lea ddeposite do n th e needle s neares t th e roadway , Smit hconclude dtha t pin e tree s ma y serv e a s rathe r

efficien t ai r filters . 6.3.2. 2 PRECIPITATIO N Precipitation , o r

we t deposition , remova l pro cesse s includ e rainou t

an dwashout . Rainou t

occur s 8 b 4

2

1. 0 0. 8 0. 6 0. 4

0. 2 -

-

-

.

- 1 1 —0 —

--•- -

1 1 1 Illl l

SAMPLIN G STATIO N 2 0 f t FRO M EDG E O F EXPRESSWA Y SAMPLIN G STATIO N 64 0 f t FRO M EDG E O F EXPRESSWA Y

1 Illl l l 1 / A 1 1 ifa 1 a 

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1 . - -

-

-

-

. .

-

—

-

-

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1 1 0 2 0 5 0 7 0 9 0 9 5 9 8 9 9 P b PARTICULATE S <STATE D SIZE , percen t Figur e 6-19 . Compariso n o f siz e distributio n o

f lea d particu late s collecte d at 2 0 an d 64 0 f t fro m a n expresswa y nort h o f Cincinnati . Ohio . Determine d b y seven-stag e Anderse n sampler. 5 8

- | 1—|— i i i i | | 1—i—|— r P b CONC . = 12.114766 7 - 3.899313 5 XLO G DISTANC E

R " -0.7 8

C O CONC . - 6.5198 9 - 1.713846 7 XLO G DISTANC E

R = -0.6 0

_L _ i _ _ i _ _i _ JL 5 0 10 0 20 0 DISTANC E FRO M EDG E O F HIGHWAY , fee t Figur e 6-20 . Atmospheri c concentratio n o f lea d an d carbo n monoxid e a s a functio n o f lo g o f distanc e fro m edg e ofhigh wa y ( R = correlatio n coefficient). 5 8 whe n particulat e matte r i s presen t

inth e super saturate denvironmen t

o f agrowing ' cloud . Th e smal l particle s (0. 1 t o 0. 2 fim) ac t a s nucle i fo r

th e formatio n o f

smal l droplets , whic hgro w int o raindrops. 4 9 Droplet s als o collec t particle s unde r 0. 1 M mb y Brownia nmotio n an db y th e water-vapo r gradient . Th e nucleatio n proces s ma y als o occu r o n particulat e matte r

presen t belo w clou dlevel , pro ducin g droplet s larg e enoug ht o b e affecte db y sedi mentation . Thes e processe s ar e referre dt o a s rainout . A secon dproces s (washout ) occur s whe n fallin g raindrop s collec t particle s b y diffusio nan d impactio n o n th e way t o th e ground . Rainou t an d 6-1 5•Il l P I I ••••• • P.8 0

washou t togethe r

ar e know n a s we t

deposition . Althoug hdat ao n th e lea dconten t o f precipitatio n ar e rathe r

limited , thos e tha t

d o exis t indicat e ahig h variability . Lazru s e t

al. 6 0 sample dprecipitatio n at 3 2 U.S . station s an dfoun dacorrelatio n betwee n gasolin e us e an dlea dconcentratio n in * rainfal l in eac harea . Similarly , ther e i s probabl y acorrelatio n betwee n lea dconcentratio n in rainfal l aji ddistanc e fro mlarg e stationar y poin t source s o f

lea demission s in th e vicinit y o f

suc hsources . Th e author s pointe d ou t tha t at leas t twic e a s muc hlea di s foun din pre cipitatio n a s in wate r

supplies , inferrin g th e exis tenc e o f aproces s b y whic hlea di s deplete dafte r precipitatio n reache s th e ground . Russia n studies 6 1 poin t t o th e insolubilit y o f

lea dcompound s in sur fac e water s an dacknowledg e thi s remova l b y natura l sedimentatio n an dfiltration . Th e intensit y o f

rainfal l appear s t o b e negativel y correlate dwithth e amoun t o f lea dwashe dou t

o f th e atmosphere . Te r

Haa r e t al. 6 2 foun dtfoa

t shower s ha dlowe r

concentration s tha n slow , eve n rainfall . Dat apresente db y Jaworowski 4 4 sho w tba t in recen t years , th e lea dconten t

in rainwate r

range dfro m0 t o 185 8 Mg/l'ter . A laborator y stud y in whic hsimulate drainfal l wa s use dt o determin e th e efficienc y withwhic h automotiv e lea dparticulate s coul db e washe dou t indicate dtha t

th e efficienc y wa s les s tha n 1 per cent. 6 3 Concentration s o f 210 P b in rainwate r

hav e als o bee n reporte db y Jaworowski 4 4 a s highl y variabl e (a s muc ha s tw o order s o f magnitud e i

mth e sam e locality ) an dno t

relate dt o seaso n o r

amioun t o f pre cipitation . Value s range dfro m0. 2 t o 30 0 pCi/liter. 4 4 Hig hconcentration s wer e foundinsam ple s collecte dfro mnorther n continenta l localities , an dlo w concentration s wer e foun din sample s fro m oceani c an dAntarcti c locations . Jaworowsk i sug gest s tha t th e difference s migh t

b e attribute din par t t o artificia l contaminatio n b y nuclea r esxplosions . 6.3.2. 3 FIEL D STUDIE S Atkin s an dKruger 6 4 conducte dafiel dsamplin g progra min Pal o Alto , California , t o determin e th e effectivenes s o f

sedimentation , impaction , rainout , an dwashou t

in removin g lea dcontaminant s fro m th e atmosphere . Rainfal l in th e are aaverage s approximatel y 3 3 c m(1 3 in)/yea r an doccur s pri maril y durin g th e lat e fal l an dwinte r months . Air born e concentration s at afreeway sit e varie dfro m 0. 3 Mg/m 3 t o amaximu mo f 1 9 Mg/m 3 iff

l t*h e fal l an d winte r seasons , an dwer e amaximu mof'9. 3 Mg/m 3 in th e spring . Durin g period s o f ligh t rawfal l inth e spring , th e maximu mconcentratio n observe dwa s

7. 4 Mg/m3

- A typica l dail y concentratio n profil e ob serve di s show ninFigur e 6-21 . Mor e tha n9 0 per cen t o f th e lea dpollutant s reachin g th e surfac e dur in g th e 1-yea

r samplin g perio dwer e collecte din dr y fallout . Dr y depositio n a s afunctio n o f distanc e fro mth e freewa y i s show n in Figur e 6-22. * Approx imatel y 1 percen t

o f th e tota l dr y fallou t

collecte d nea r th e expresswa y wa s lead . We t depositio n(ap proximatel y 3 3 c mo r

1 3 ino f

rai n pe r

year ) ac counte dfo r

5 t o 1 0 percen t

o f th e lea dremova l at th e samplin g sites . A summar y o f th e fiel ddat ai s show n inTabl e 6-10 .

E • 5 1 5

MID - 2 NIGH T 4 6 8 1 0 NOO N 2 TIM E O F DA Y 4 6 8 1 0 MID NIGH T Figur e 6-21 . Atmospheri c lea d concentratio n at freewa y sit e i n Pal o Alto , California , o n August 15,1966. 6 3 ? 1. 0 N e n E 1 v ]

I I I II I I I

—^ V l=STD . DEV . 1 N . X.9.0x10V B06 L

N . (SE E FOOTNOT E I N TEXT I



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- 1 • 1 1 1 I t I I 1



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-

- ' x - I N 10 0 20 0 50 0 100 0 200 0 500010,00 0 50.00 0 100,00 0 DISTANC E FRO M FREEWA Y{X), foo t Figur e 6-22 . Averag e lea d i n dry fallou t a s a functio n o f dis tanc e fro m th e freeway. 6 3 'Figur e 6-2 2 i s a semi-lo g plo t o f th e thre e averag e lea d value s a s a functio n n f dis tanc e fro m th e freeway . Th e dat a appea rt o fal l alon g a straigh t line , suggestin g tha t th e relationshi p hetwee n lea d i n fal l out . I. , an d distanc e fro m th e freeway . X . ca n h e describe d b yX = ae h l - wher e a an d b ar e constants . Fro m th e semi-plot , th e ap propriat e value s fo ra an d b ar e a = 9. 0 xI0 4 ; b o -8.06 . i f L i s expresse d i n mgm 2 -wt can d X i s expresse d i n feet . Therefor e X = 9. 0 xIO 4 e**- 0ft k Th e are a unde rthi s curve , fro m X , = 5 0 f t t o X 3 = 26,90 0 ft , shoul d represen t th e tota l amoun t o f lea d deposite d i n th e Pal o Alt o are a fo reac h l-f i sectio n o f freeway . Thi s valu e i s 7.8 5 g/ft . Th e are a unde rth e curv e fro m L = 0.9 5 mg/ft^-w k t o L • 0 shoul d represen t th e tota l amoun t o f lea d tha t wa s remove d h ysedimentation , assumin g tha t th e dat a ca n b e extrapolate d pas t 26,90 0 ft . Thi s valu e i s I I. I g/ft . Thi s indicate d tha t a n averag e o f 7 0 percen t o f th e lea d tha t wa s remove d h ysedi mentatio n wa s remove d withi n 5 mile s o f th e source . 6-1 6P.8 1

TABL E 6-10 . SUMMAR YO F FIEL D DAT A FRO M PAL O ALTO , CALIFORNIA '

6 4 Freeway 3 {Bayshore ) Resi dentia l Foot hill s Lea d i n dr yfallout : Average , mg/fr-w k Amoun t removed , mg/f t -y r Lea d i n rainfall : Average , mg/lite r Amoun t removed , mg/f t -y r Averag e ai rconcentration , Mg/m 3 Pb/tota l solid s i n ai r Pb/nonvolatil e solid s i n dryfallou t 0.9 2 49. 4 0.18 1 3.2 5 7.3 0 0.042 0.2 4

11. 7 0.14 9 3.6 6 2.2 8 0.01 8 0.15 3

8. 3 0.03 5 0.9 2 1.9 0 0.01 6 0.011 2 0.010 2 0.004 9 Andre n e t

al. 6 5 evaluate dth e contributio n o f we t an ddr y depositio n o f

lea di n astud y o f

th e Walke r Branc hWatershed , Oa k Ridge , Tennessee , durin g th e perio dJun e 197 3 t o Jul y 1974 . Th e mea npre cipitatio n in th e are ai s approximatel y 13 0 cm/yea r (5 1 in/year) . Th e majo r atmospheri c emission s in th e vicinit y o f

Oa k Ridg e ar e derive dprimaril y fro m thre e coal-fire dstea mplants . A foundr y an dferro allo y plan t

approximatel y 64. 5 k m(4 0 miles ) t o th e wes t wer e assume dt o hav e amino r impac t becaus e o f

orographi c barriers . Result s reporte dfo r th e perio dJanuar y throug hJun e o f 197 4 ar e pre sente di n Tabl e 6-11 . Rainfall , o r we t deposition , contribute dapproximatel y 6 7 percen t o f th e tota l depositio n fo r

th e period . TABL E 6-11 . DEPOSITIO N O F LEA D A TTH E WALKE R BRANC H WATERSHED , 1974 6 5 Lea d depositio n (g/ha ) Dr y Januar y February Marc h Apri l Ma y Jun e Tota l Averag e 34. 1 6. 7 21. 6 15. 4 26. 5 11. 1 115. 4 19. 2 < 16. 7 3. 3 10. 6 7. 5 13. 0 5. 4 56. 5 9. 4

a Tota l depositio n — 17 2 g/ha . We t depositio n —67 percen t o l total . yuntzicke r

e t al. 1 0 estimate dth e flo w o f automo bile-emitte dlea di n th e Lo s Angele s Basi n base do n measurement s o f

particl e size , atmospheri c con centrations , an dsurfac e depositio n o f lea da t variou s site s aroun dth e Basin . A flow diagra mbase do nth e stud y an dmodifie db y Schuc k an dMorgan 6 6 i s show n i n Figur e 6-23 . O f th e lea demitte dfro mau tomobil e exhaus t

in th e Basi n (estimate dt o b e abou t 1 8 ton s pe r

day) , th e investigator s calculate dtha t abou t 5 6 percen t

wa s deposite dnea r

th e sourc e (nea r deposition) , 1 2 percen t wa s deposite din th e Basi n bu t i n area s remove dfro mth e sourc e (far deposi tion) , an dabou t

3 2 percen t

wa s transporte dou t

o f th e Basi nb y th e wind . Th e value s presente dfo r depositio n an dwin dremova l wer e fo r dr y weathe r onl y (i.e. , dr y depositio n only) .

INPU T 23. 7 metri c ton s Pb/da y

25 % 

# t REMOVE D B YSTREE T CLEANIN G 6 % SEWAG E 40 % J NEA R DEPOSITIO N STREE T 8 % LAN D

32 % RUNOF F 2 % V

0.6 4 metri c ton s Pb/da y I 10 % FA R DEPOSITIO N LAN D 

# T ^ COASTA L WATER S Figur e 6-23 . Fat e of lea d contribute d fro m automotive traffi c i n Lo s Angele s Basin. 0 3 Robert s e t

al. 6 7 foun dan exponentia l decreas e in dustfal l wit hdistanc e aroun dtw o secondar y smelter s (Figur e 6-24) . Th e author s conclude dtha t th e hig hrat e o f

fallou t aroun dth e smelter s origi nate dfro mepisoda l large-particulat e emission s fro mlow-leve l fugitiv e source s rathe r tha n fro mth e stack . Thi s bein g th e case , sedimentatio nwoul db e th e principa l remova l process . Th e lea din dustfal l value s decrease dwel l ove r 9 0 percen t

withi nadis tanc e o f 300m .

100 0

50 0 I I 1 SMELTE R A :

\ SMELTE R B : 1 1 1 Y= 6,10 0 -2.56 0 lo g X R = -0.8 1 p < 0.00 1 9 6 SAMPLE S A T 1 6 SITE S — Y= 89 6 - 34 0 lo g X R - -0.6 3 p <0.00 1 3 4 SAMPLE S A T6 SITE S

-

U 20 0 30 0 40 0 50 0 DISTANC E FRO M STACK , meter s Rgur e 6-24 . Contaminatio n o f dus t b y lea d emission s fro m tw o secondary smelters . Soli d an d dashe d line s ar e fitte d curve s correspondin g t o th e regressio n equations ; dotte d line s ar e a n extrapolate d fit ; U indicate s correspondin g value s foun d I n urba n contro l areas. 6 6 6-1 7P.8 2

Studie s suc ha s thos e describe dabov e clearl y indi cat e tha t lea di s effectivel y remove dfro mth e at mospher e b y dr y an dwe t depositio n processes , an d tha t atmospheri c concentration s ar e significantl y in fluence db y thes e remova l mechanism s eve n in th e immediat e vicinit y o f th e source . Th e rat e o f remova l i s highl y dependent , however , o n th e siz e distributio n o f

th e particles , th e natur e an dcharac teristic s o f

th e depositio n surfaces , airborn e con centrations , an datmospheri c condition s includin g stability , winds , an dprecipitation . I n dr y weather , th e lea dwil l b e deposite do n surface s in th e formo f dustfal l b y sedimentation , diffusion , o r inertia l mechanism , dependin g primaril y o n th e siz e o f th e particles . Mas s depositio n nea r th e source s will b e controlle dprimaril y b y sedimentatio n o f larg e parti cles , wherea s th e smalle r particle s will remai nair born e longer , b e transporte dfurthe r b y th e wind , an db e remove dprimaril y b y diffusio n an dinertia l mechanisms . Th e characteristic s o f

th e surface s o n whic hth e lea di s deposite dwil l significantl y influenc e th e depositio n an dretention . Depositio n will b e greate r in awoode dare atha n o n pave dsurface s o r shor t grass . Building s als o will influenc e th e dr y deposi tion , althoug hther e ar e few dat aavailabl e t o quan tif y th e effect . I n area s withhighe r annua l rainfall , remova l b y precipitatio n (we t deposition ) become s mor e importan t

an dma y b e th e dominan t process . Al l o f thes e factor s substantiall y influenc e poten tia l huma n lead-exposur e pattern s —bot hinhala tio n o f airborn e lea dan dpossibl e ingestio n o f dus t containin g lead . Th e dr y depositio n remova l mechanism s deplet e th e airborn e concentration s bu t deposi t th e materia l in th e formo f dust . Th e factor s controllin g dr y depositio n the n becom e extremel y importan t

fro mth e standpoin t

o f potentia l exposur e pattern s fo r

dust , sinc e the y ma y strongl y influenc e tempora l an dspatia l variations . Becaus e o f sedi mentatio n o f

larg e particles , dustfal l rate s (mass ) will b e highes t

immediatel y adjacen t

t o roadway s wit hdens e automobil e traffi c an dnea r stationar y source s o f

al l type s wher e lea dma y b e emitted . Thes e rate s wil l diminis ht o arathe r lo w valu e in area s remot e fro msource s an dwher e th e smal l par ticle s ar e remove dprimaril y b y diffusio n an diner tia l mechanisms . Th e accumulatio n o n th e depositio n surface s wil l depen do n th e rat e o f depositio n an dth e rat e a t whic hth e materia l i s cleane dfro mth e surface s b y precipitatio n o r

b y mechanica l mean s suc ha s stree t sweepin g o r

vacuuming . Dus t

enterin g building s o r home s b y ai r

transpor t

wil l usuall y b e deposite do n fla t surface s suc ha s floor s o r furniture . Th e sam e physica l processe s wil l contro l th e rat e o f deposi tion . Th e potentia l exposur e level , particularl y fo r youn g children , will depen do n th e accumulation , whic hagai n will b e influence db y th e depositio nrat e an dth e frequenc y an dmethod s o f cleaning . I n oc cupationa l environment s wher e fugitiv e dus t emis sion s ar e high , accumulatio nwil l b e rapi dif surface s ar e no t frequentl y cleaned . Significan t amount s o f thi s dus t ma y b e carrie do n clothin g int o th e home s o f worker s an dcontribut e furthe r t o th e tota l lead dus t loadin g in th e hom e environment . Emissio n rate s fro mautomobil e traffi c an dfro m stationar y source s ar e highl y variabl e intime , eve n o n a nhourl y basis . Sinc e th e residenc e tim e o f larg e particle s inth e atmospher e i s o nth e sam e orde r o r less , th e dustfal l rate s inth e immediat e vicinit y o f source s shoul dals o b e highl y variable . Thi s i s reflecte dinairborn e concentration s measure dver y nea r th e source . A s aconsequenc e o f

th e numbe r

o f variable s in volve dan do f

th e tempora l an dspatia l variation s occurring , it

i s no t possibl e t o quantif

y huma n ex posur e in uncontrolle dcase s withou t th e us e o f

per sona l monitors . Estimate s o f suc hexposur e ma y var y b y an orde r

o f magnitud e o r

greater . Fo r

agive n emissio n pattern , on e ca n generall y conclud e tha t potentia l exposur e fro mlea dindus t shoul db e greates t (1 ) i ndr y seasons , (2 ) inarea s wit hspars e vegetation , (3 ) withi n afe w hundre dmeter s o f

th e sources , (4 ) unde r

condition s o f

stabl e atmospheres , (5 ) durin g th e mornin g an dafternoo ntraffi c rus h hour s inth e vicinit y o f

freeways , an d(6 ) durin g pea k productio nperiod s o f

stationar y source s (usuall y durin g th e day) . 6.3.2. 4 RESUSPENSIO N Th e threshol dstress , whic hmus t b e exceede d befor e aparticl e i s resuspende dfro masurface , i s a functio n o f

th e particl e properties , particl e size , an d th e surfac e properties . A particl e o f agive nsiz e an d densit y will resuspen dmor e easil y fro masmoot h surfac e tha n fro manirregula r surfac e suc ha s an asphal t road . Particle s o n adir t roa do r othe r soi l surface s ma y becom e attache dt o soi l particle s an d behav e quit e differentl y fro ma niner t fre e particle . Thi s proces s o f

weatherin g tend s t o reduc e resuspen sion . Moisture , influence db y atmospheri c variable s suc ha s wind , precipitation , humidity , an dsola r radiation , ma y inhibi t

resuspension . Dat ain th e literatur e o nresuspensio n sho w tha t thi s proces s i s no t

wel l understood , an dhenc e resus pensio nrate s canno t

yet b e predicte dt o an y degre e 6-1 8o f

accuracy . Fo r

example , Mishima 6 8 indicate s tha t reporte dresuspensio n factors * var y ove r 1 0 order s o f magnitud e fro m10" 2 t o 10"" . (Th e resuspensio n factor , in m 1 , equal s th e airborn e concentration , in ng/m 3 , divide db y th e groun dsourc e concentration , in ng/m 2

. ) I t

i s useful , however , t o examin e dat a fro mmor e controlle dresuspensio n experiment s in orde r t o obtai n aqualitativ e ide ao f expecte dlea d resuspensio n rates . Sehmel 6 9 ha s examine dth e resuspensio n o f Zn S particle s smalle r

tha n 2 5 micron s fro ma n asphal t roa dsurface . H e foun dtha t whe n aca r

wa s drive n acros s th e recentl y applie dtracer , 0.00 1 percen t t o 1. 0 percen t

o f th e materia l wa s resuspended . However , th e fractio n resuspende ddecrease db y 2 t o 3 order s o f

magnitud e whe n a30-da y perio delapse d betwee n applicatio n o f th e trace r

an dth e ca r passage . Th e fractio n resuspende dpe r vehicl e passag e in crease da s afunctio n o f vehicl e spee dan dwa s inde penden t o f win dvelocitie s fo r

th e tes t conditions . Th e fractio n resuspende dpe r vehicl e passag e wa s greate r fo r adriv e throug hth e trace r tes t lan e tha n o n th e adjacen t

lan e an dgreate r

fo r a3/4-to ntruc k tha n fo r acar . Thes e result s sugges t tha t resus pensio n o f

lea dfro mroadway s ma y pla y asignifi can t rol e in th e overal l transpor t o f lea dawa y fro m automotiv e sources . Thi s ma y b e importan t con siderin g th e conclusion s o f Huntzicke r

e t al. 1 0 tha t

a considerabl e fractio n o f th e emitte dlea ddeposit s directl y o n th e roadways . I n anothe r

experiment , Sehme l an dLloyd 7 0 ex amine dth e resuspensio n o f \0-fim monodispers e uranin e particle s fro masmoot hsurfac e inth e laboratory . The y foun dtha t th e fractio n o f

materia l resuspende dpe r

secon dvarie dfro mIO" 6 t o 10" 3 fo r win dspeed s o f

16. 5 t o 18. 3 m/sec . The y als o measure dth e resuspensio n o f CaMo 4 ove r

sand y soil. 7 0 Th e fractio n o f

materia l resuspende dpe r sec on drange dfro m2 x 10 l 0 t o 2. 2 x 10 8 fo r wind s o f 1. 3 t o 2 0 m/sec . A limite damoun t

o f dat ao n lea dresuspensio n i s als o available . Figur e 6-2 5 show s th e depositio no f lea dfoun da s afunctio n o f heigh t abov e aroo f

sur face. 7 2 Th e lea dwa s deposite do n flat Teflo nplate s mounte da t

variou s heights . Th e greate r deposition s clos e t o th e roo f

ar e believe db y th e investigator s t o b e du e t o resuspende droo f dust . Th e environmenta l consequenc e o f sal t particl e resuspensio n fro mroad s ha s bee n reporte db y Smith. 7 3 Needle s fro mwhit e pin e plante dadjacen t t o a n interstat e highwa y in Connecticu t showe dex cessiv e sodiu man dcalciu mconten t resultin g fro m airborn e sal t resuspensio n fro mth e highway . Th e depositio n o f

airborn e sal t

appear s t o b e simila r

t o tha t o f lea dfro mautomobil e exhaust. 6 9

35 0

30 0

25 0

20 0

15 0

10 0

5 0 

### 1 1

-

-

-

-



### 1 1 !

/

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### 1 °^ U 2 0 P b DEPOSITION , ng/cm'-da y Figur e 6-25 . Tota l depositio n o flea d o n Teflo n plate s a t variou s height s abov e th e roo fof Kec k

Laboratories , Califor ni a Institut e o

f Technology , Pasadena. 7 1 Bau me t al. 7 4 sample dairborn e particulat e fo r a perio do f abou t 2 year s at

severa l location s in Port land , Oregon , usin g paraffin-coate dMyla r film s withfour - an dfive-stag e Lundgre nimpactors . Soi l an ddus t samples , bot hsurfac e an dsubsurface , wer e als o take n at

th e air-samplin g sites . Sample s wer e analyze dfo r

lea dan dothe r

elements . Chemica l ele menta l balanc e method s wer e use dt o calculat e soi l an ddus t burden s in th e air . Th e author s repor t tha t greate r tha n 9 0 percen t

o f th e submicrometer-size d airborn e particle s wer e associate dwit hautomotiv e emissions . Th e large r

particle s wer e reporte dt o b e contribute dabou t

equall y b y resuspende dstree t dus t an ddirec t

emission s fro mautomobiles . Thes e dat asugges t

tha t lea dresuspensio nma y pla y a n importan t

rol e inth e transpor t

o f lead . A t present , however , i t

i s no t possibl e t o reac hquantita tiv e conclusion s abou t

thi s mechanism . Siz e distri butio nmeasurement s o f ambien t lea dpresente dher e an delsewher e in th e literatur e represen t airborn e dat atha t hav e bee n influence db y th e combine dfac tor s o f atmospheri c transport , deposition , an d resuspension . 6.3. 3 Model s Ther e i s an extensiv e bod y o f literatur e o nat 6-1 9P.8 4

mospheri c transpor t

an ddiffusio n models. 75 ' 7 9 A detaile ddiscussio n i s beyon dth e scop e o f thi s docu ment . Th e mathematica l model s ar e usuall y base d o n th e basi c Gaussia n plum e mode l emanatin g fro m th e earl y wor k

o f Sutton 4 6 an dPasquill 4 7 an dwel l describe db y Gifford. 7 6 Stern 7 7 provide da n ex cellen t revie w o f

ai r qualit y modelin g technique s fo r bot hrura l an durba n modelin g situations . Experi menta l dat adescribin g th e pollutan t concentration s fro mpoin t

source s sho w that , in spit e o f wid e varia tions , thes e plume s exhibi t astron g tendenc y towar d aGaussia n o r

norma l distributio n a s astatistica l average . I n simpl e terms , parameter s reflectin g th e turbulen t componen t

defin e th e horizonta l an dver tica l dimension s o f

apollutan t

clou din avertica l plan e perpendicula r

t o th e mea n win dvelocity . Cermac k e t al. 8 0 hav e use dth e win dtunne l t o mode l physicall y th e atmospheri c boundar y laye r ove r urba n area s t o determin e th e pollutan t transpor t characteristics . 6. 4 TRANSFORMATIO N AN D TRANSPOR T I N OTHE RENVIRONMENTA L MEDI A 6.4. 1 Soil s Numerou s studie s hav e show n significan t con taminatio n o f

soil s b y th e emissio n o f lea dfro m mobil e an dstationar y source s an dthroug hth e dis posa l o f wast e products . Excellen t review s o f

th e earl y literature , a s wel l a s report s o n mor e recen t research , hav e bee n publishe db y member s o f ajoin t researc hstaf

f fro mColorad o Stat e Universit y an d th e Universitie s o f

Missour i an dIllinois. 202 9 Man y o f th e studie s o f

lea dbefor e 197 3 wer e limite dt o analysi s fo r

elementa l lea dan ddi dno t includ e analysi s fo r

associate dions . Suc hinformatio ni s no t sufficien t t o permi t

athoroug hexaminatio n an d understandin g o f

(1 ) transformatio n an dtranspor t processe s tha t

occu r amon g th e environmenta l media , (2 ) mobilit y o f

lea din soils , (3 ) uptak e an d distributio n o f

lea din plants , an d(4 ) th e overal l im pac t o f lea do n huma n healt han decosystems . Infor matio n o n th e chemica l form s o f lea di s needed . Soi l i s acomple x matri x compose do f severa l hundre ddifferen t

compounds , onl y asmal l fractio n o f whic har e lead . Mos t

analytica l technique s ar e no t capabl e o f

providin g positiv e identificatio n o f specifi c compound s unles s separatio n method s ar e use dtha t d o no t alte r th e lea dcompounds . Recently , nondestructiv e separation/preconcentratio n tech nique s hav e bee n develope dan duse db y th e Col orad o Stat e Universit y researc hgrou p t o determin e lea dcompound s i n soi l an dplants. 1 0 Lea dcontaminant s ar e deposite do n soi l b y dr y an dwe t depositio n processes . Presen t understandin g o f th e chemica l reaction s involvin g thes e particle s onc e the y ar e deposite dint o o r o nth e soi l i s in complete. 8 1 Earl y wor k indicate s tha t

lea dprobabl y react s wit hsoi l anions , e.g. , S0 4 = , P0 4 = , o r C0 3 = , o r withsom e organi c o r

cla y complex. 8 2 Thes e reac tion s woul dten dt o mak e th e P b insoluble , thu s in hibitin g rapi dmobilit y i nth e soi l o r plan t a s wel l a s microbia l uptake . Direc t evidenc e supportin g thes e reaction s i s limited . I nastud y b y Lagerwerf f an d Brower, 8 3 lea dwa s precipitate dinN a+ -treated , alkalize dsoils . Th e solubilit y o f th e precipitat e in crease dwit hdecreasin g p H an dconcentratio n o f NaCl . Furthermore , absorptio no f soi l lea db y hy drou s oxide s o f

iro n an dmanganese , an dit s conse quen t immobilization , ha s bee n reporte db y Gadd e an dLaitinen. 8 4 Studie s hav e identifie dcatio nexchang e capacity , organi c matte r

content , pH , soi l type , an dsoi l drain ag e a s th e importan t

factor s influencin g th e mobilit y o f lea dinsoils. 8 5 Santillan-Medran o an dJurinak 8 6 conducte dbatc hequilibriu mstudie s t o obtai n solubilit y dat afo r

lea dan dcadmiu minsoil . Lea d solubilit y decrease din th e soil s a s p H increased . Th e lowes t value s wer e obtaine din calcareou s soil . I n noncalcareou s soil , th e solubilit y o f lea dappear s t o b e regulate db y Pb(OH) 2 , Pb 3 (P0) 4 ) 2 , Pb 4 0(P0 4 ) 2 , Pb 5 (P0 4 ) 3 0H , an deve n PbC0 3 , dependin g o n th e pH . Th e creatio n o f

organi c chelatin g agent s b y biologi c activit y serve s a s on e o f th e mos t

effectiv e processe s o f

meta l mobilizatio n o r

immobilizatio nin th e soil . Thes e agent s ar e eithe r plan t products , microbia l metabolities , o r humi c compound s (humi c acids) . Th e latte r

ar e capabl e o f

precipitatin g lead . Th e amount s an dtype s o f organi c matte r

pre sen t appea r t o provid e a n importan t contro l mechanis mfo r

th e movemen t

o f heavy-meta l ion s in soi l systems . Th e associatio no f lea dan dorgani c matter , however , i s no t alway s empiricall y consis tent. 8 7 Olso nan dSkogerboe 2 9 preconcentrate dlea d compound s in roadsid e soi l sample s an duse dX-ra y powde r diffractio ntechnique s fo r compoun diden tification . Th e lea dcompound s in eac hsoi l fractio n examine dar e show n i nTabl e 6-12 . Th e mos t abun dan t lea dsal t

foun dwa s th e relativel y insolubl e PbSo 4 . Th e author s not e tha t generall y 7 0 percen t

o r mor e o f th e tota l lea din th e soil s examine dwa s con taine din th e dens e fraction s an dtha t th e majorit y (>5 0 percent ) o f

thi s lea dwa s presen t

a s sulfate . Th e result s indicat e tha t oxide s presen t

in th e soi l 6-2 0wer e mino r constituent s compare dt o th e sulfat e concentrations . Sinc e lea dbromochlorid e com pound s ar e th e principa l constituent s o f fres hauto mobil e exhaus t

emissions , conversio n t o lea dsulfat e mus t hav e occurre deithe r

in th e atmospher e o r

in th e soil . Th e author s sugges t tha t sulfuri c aci d forme dfro mS0 2 in th e atmospher e o r at th e soi l interfac e ma y reac t

withth e lea dparticulat e t o form lea dsulfate . Reactio n withth e sulfat e io n als o ma y occu r in th e soi l in contac t

withgroundwater. 2 4 Th e result s o f Le e e t al. 9 (Sectio n 6.2.2.1 ) suppor t thes e genera l contentions . Dat aar e limite dregardin g th e chemica l composi tio n o f lea din soi l contaminate db y emission s fro m stationar y sources . Lea dsulfid e an dlea dchlorid e ar e though t

t o b e th e majo r

constituent s in soil s in th e vicinit y o f

minin g industries , an dlea doxid e i s th e chie f on e in th e vicinit y o f

smelters . Th e presenc e o f lea dsulfid e a s th e primar y compoun di n soil s alon g amine-acces s roa din Missour i ha s bee nre ported , (Tabl e 6-12) . Analytica l dat aconfirmin g th e othe r compound s mentione dabov e ar e no t availa ble . 6.4. 2 Wate r 6.4.2. 1 INORGANI C Th e chemistr y o f

lea din an aqueou s solutio ni s highl y comple x becaus e th e elemen t ca n b e foun din amultiplicit y o f

forms . He man dDuru mhav e reivewe dth e chemistr y o f lea din wate r

indetail, 8 8 an dth e aspect s o f

aqueou s lea dchemistr y tha t ar e german e t o thi s documen t ar e discusse din Chapte r 3 . Natura l concentration s o f lea di n lead-or e deposit s d o no t

normall y mov e appreciabl y in groun do r

surfac e water . An y lea ddissolve dfro m primar y lea dsulfid e or e tend s t o combin e wit hcar bonat e o r

sulfat e ion s t o (1 ) forminsolubl e lea dcar bonat e o r

lea dsulfate , o r

(2 ) b e absorbe db y ferri c hydroxide. 8 7 A n outstandin g characteristi c o f lea di s it s tendenc y t o formcompound s o f lo w solubilit y wit hth e majo r

anion s o f

natura l water . Th e hydrox ide , carbonate , sulfide , an dmor e rarel y th e sulfat e ma y ac t a s solubilit y controls . Th e amoun t o f lea d tha t ca n remai n in solutio n in wate r i s afunctio n o f th e p H o f

th e wate r

an dth e dissolve dsal t content . Equilibriu mcalculation s sho w tha t th e tota l solubilit y o f

lea din har dwate r

(p H >5.4 ) i s abou t 3 0 fig/\iter

an dabou t

50 0 ^tg/lite r

in sof t wate r (p H <5.4). 8 9 Lea dsulfat e (PbS0 4 ) i s presen t in sof t wate r an dlimit s th e lea dconcentratio n in solution . Abov e p H 5.4 , PbC0 3 an dPb 2 (OH) 2 C0 3 limi t th e TABL E 6-12 . LEA D COMPOUND S IDENTIFIE D I N ROADSID E

SOIL S B YX-RAYPOWDE R DIFFRACTIO N TECHNIQUES 2 9 Locatio n an d soi l fractio n Fort Collins : Magneti c Nonmagneti c Denver : Magneti c Nonmagneti c Chicago : Magneti c Nonmagneti c Chicago : Magneti c Nonmagneti c Missouri : Magneti c Nonmagneti c Compound s foun d PbS0 4 PbS0 4 PbOPbS0 4 Pb0 2 PbO ° PbS0 4 PbS0 4 PbS0 4 Pb O PbS0 4 PbS0 4 PbS0 4 None c Pb S PbS0 4 Estimate d concentrations 8 Majo r Majo r Mino r Trac e Trac e Majo r Majo r Majo r Majo r Mino r Majo r Majo r Majo r Mino r

a Majo rindicate s th e principa l portio n o f lea d presen t i n th e soi l fractio n indicate d and . therefore , th e principa l portio n o f th e soi l sample . Mino rrefer s l o approx imatel y1 t o 1 0 percen t o l th e lea d i n th e respectiv e fractions . Trac e quantitie s ar e les s tha n approximatel y1 percen t o f th e tota l i n eac h fraction . D Assignmen t i s base d o n th e presenc e o f onl yth e mos t intens e d-spacin g an d i s therefor e questionable . c Comple xd-spacin g patter n obtaine d wit h al l intensitie s low ; positiv e assign men t o f an yon e compoun d o rgrou p o f compound s i s questionable . concentration . Th e carbonat e concentratio n i s in tur n dependen t

o nth e partia l pressur e o f C0 2 a s wel l a s th e pH . Calculation s b y He man dDurum 8 8 sho w tha t

man y rive r

water s in th e Unite dState s hav e lea dconcentration s nea r th e solubilit y limit s impose db y thei r

p H level s an dcontent s o f dissolve d C 0 2 species . Becaus e th e influenc e o f changin g tem peratur e an dp H ma y b e substantial , observe dlea d concentration s ma y var y significantl y fro m theoreticall y calculate dones . Lazru s e t

al. 6 0 calculate dtha t

a s muc ha s 13 8 g/ha-m o o f

lea dma y b e deposite db y rainfal l in «om e part s o f th e northeaster n Unite dStates . Assumin g a n averag e annua l rainfal l runof f o f 5 0 c m(—2 0 in) , th e averag e concentratio n o f lea dinth e runof

f woul dhav e t o b e abou t 33 0 /ug/lite r

t o remov e th e lea da t th e rat e o f

13 8 g/ha-mo . Concentration s a s hig ha s 33 0 /txg/liter

coul db e stabl e in wate r withp H nea r 6. 5 an da n alkalinit y o f abou t 2 5 n g bicar bonat e ion/lite r

o f water . Wate r

havin g thes e proper tie s i s commo n i nrunof f area s o f

Ne w Yor k

Stat e an dNe w England ; hence , th e potentia l fo r hig hlea d concentration s exist s there . I nothe r areas , th e averag e p H an dalkalinit y ar e s o hig htha t les s tha n 1 /ug/lite r o f lea dcoul db e retaine dinsolution s a t equilibrium. 8 7 6-2 1P.8 6

A significan t

fractio n o f

th e lea dcarrie db y rive r wate r ma y b e in a n undissolve dstate . Thi s nonsolut e lea dca n consis t

o f colloida l particle s in suspensio n o r large r undissolve dparticle s o f lea dcarbonate , oxide , hydroxide , o r

othe r lea dcompound s incor porate din othe r

component s o f

particulat e lea d fro mrunoff, eithe r

a s sorbe dion s o r

surfac e coating s o n sedimen t

minera l particle s o r

carrie da s apar t

o f suspende dlivin g o r

nonlivin g organi c matter. 8 7 A laborator y stud y b y Hem 9 0 o f sorptio n o f

lea db y ca tio n exchang e indicate dtha t amajo r par t o f th e lea d in strea mwate r

ma y b e adsorbe do n suspende dsedi ment . Figur e 6-2 6 illustrate s th e distributio n o f lea d output s betwee n filtrat e an dsolid s in strea mwate r fro mbot hurba n an drura l compartments , a s re porte db y Rolf

e an dJennett. 9 1 Th e majorit y o f lea d outpu t i s associate dwithsuspende dsolid s in bot h urba n an drura l compartment s withver y littl e dis solve din th e filtrate . Th e rati o o f lea din suspende d solid s t o lea din filtrat e varie s fro m4: 1 in th e rura l compartmen t

t o 27:1 in th e urba n compartment .

100

s o

0 _

- SHWl l SUSPENDE D SOLID S ^-^ j FILTRAT E

,,,II, I ,ii ' 

# f ^ -

/V/ ^ ^ Figur e 6-26 . Lea d distributio n betwee n filtrat e an d suspende d solid s I n strea m wate r fro m urba n an d rura l compartments." 0 Th e concentratio n o f

lea dusuall y reporte drepre sent s asomewha t

arbitraril y define dsolut e fraction , separate dfro mth e nonsolut e fractio n b y filtration . Mos t filtratio n technique s canno t b e relie do nt o remov e al l colloidal-size dparticles . Upo n acidifica tio n o f th e filtere dsample , whic hi s usuall y don e t o preserv e i t

befor e analysis , th e colloida l materia l tha t passe s throug hi s dissolve dan dreporte din tha t form . Usuall y th e solid s remove dfro masurfac e wate r sampl e b y filtratio n ar e no t analyze dfo r

lead . Bu t eve n th e lea di n rainfal l ca n b e mainl y particu late , an dthu s i t

wil l b e necessar y t o obtai n mor e in formatio n o n th e amount s o f lea dtransporte din nonsolut e form 8 7 befor e avali destimat e ca n b e ob taine do f th e effectivenes s o f

runof f in transportin g lea dawa y fro marea s wher e it ha s bee n deposite db y atmospheri c fallou t

an drain . 6.4.2. 2 ORGANI C Th e organi c component s o f soil-wate r

syste mar e a n extremel y divers e grou p o f compound s tha t

in clude s carbohydrates , amin o acids , phenoli c an d quinoni c compounds , organi c acids , nuclei c acids , enzymes , porphyrins , an dhumi c materials. 8 7 I nad ditio nt o th e natura l organi c compound s presen t in soils , stream s an dlake s contai n organi c sediment s an dsuspende dsolid s tha t hav e bee n derive dfro m municipal , agricultural , an dindustria l wastes . Thes e waste s includ e carbohydrates , proteins , nuclei c acids , enzymes , lipids , an dman y othe r organi c com pound s foun dinlivin g systems . I n addition , oils , plasticizers , polymers , an dman y othe r organi c com pound s ar e discharge dt o natura l waterway s b y man ufacturin g an dchemica l industries . Th e interactio n o f lea dwit hthes e organi c compound s i s stil l no t wel l understood , bu t

mos t o f thes e organi c material s ca n confidentl y b e expecte dt o for mcomplexe s withlea d (an dothe r

metals) , sinc e the y al l contai n availabl e dono r site s fo r complexation . A discussio n o f meta l complexatio ni s presente din Chapte r 3 an dAppen di x B . Th e presenc e o f

fulvi c aci d( aconstituen t o f soi l humi c materials ) in wate r ha s bee n show n t o increas e th e rat e o f

solutio n o f

lea dsulfid e 1 0 t o 6 0 time s ove r tha t o f awate r solutio na t

th e sam e p H tha t

di d no t contai n fulvi c acid. 879 2 A t p H value s nea r

7 , solubl e lead-fulvi c aci dcomplexe s wer e presen t in solution . A t

initia l p H value s betwee n 7. 4 an dabou t 9 , th e lead-fulvi c complexe s partiall y decomposed , an dlea dhydroxid e an dcarbonat e wer e precipi tated . A t initia l p H value s o f

abou t 10 , th e lead fulvi c aci dcomplexe s agai nincreased . Thi s increas e wa s attribute dt o dissociatio n o f phenoli c group s at hig hp H values , whic hincrease s th e complexin g capacit y o f

th e fulvi c acid . Bu t

i t ma y als o hav e bee n du e t o th e formatio no f solubl e lead-hydroxy l com plexes . I nsummary , th e complexin g o f lea db y mos t

o f th e commo n sulfur- , phosphorus- , oxygen- , an d nitrogen-containin g ligand s mean s tha t lea dwil l ac cumulat e inlivin g an dnonlivin g organi c compo nent s o f soil-wate r

an dsediment-wate r

systems . Th e livin g an dnonlivin g organi c component s ar e no t in dependent , o f

eac hother , bu t

the y ar e constantl y interactin g a s th e livin g component s metaboliz e th e nonlivin g component s o f th e syste man dthe ndie , contributin g thei r

remain s t o th e poo l o f nonlivin g compound s in th e system . Th e fat e o f heav y metal s in thi s proces s ha s no t

bee nelucidated ; bu t

th e sedi men t in acontaminate dsurface-wate r bod y wil l serv e a s alarg e reservoi r tha t ca n provid e lea dan d othe r metal s t o th e biot ao f th e syste meve n afte r 6-2 2heavy-meta l pollutant s hav e cease dt o b e in troduced . Mos t

attentio n ha s bee n give n t o th e heav y metal s dissolve din th e wate r phas e o f surfac e wate r rathe r tha n t o th e complexe dmetal s in th e sedimen t phase , thoug hsediment s probabl y contai n ahighe r amoun t o f lead. 8 7 Th e biotransformatio n o f lea dt o volatil e tetra methy l lea dconstitute s on e mechanis mb y whic h lea dma y leav e sediment-wate r systems . Th e direct , biologica l methylatio n o f certai n inorgani c lea d compound s b y lak e sedimen t microorganism s ha s bee n reported. 93

- 9 4 Al l th e lak e sediment s teste d wer e abl e t o transfor mtrimethy l lea dt o tetramethy l lead, 9 3 bu t

onl y som e o f

th e sediment s wer e abl e t o transfor mlea dnitrat e an dlea dchlorid e int o tetramethy l lead . N o biotransformatio n occurre d whe n th e lak e sediment s wer e incubate dwithlea d oxide , lea dhydroxide , lea dbromide , lea dcyanide , o r lea dpalmitate. 9 3 Certai n pur e bacteria l isolate s (se e Chapte r

8) fro mthes e lak e sediment s wer e show n t o transfor mtrimethy l lea dt o tetramethy l lea din th e anaerobi c incubatio n syste mused. 9 3 Th e conversio n o f

th e tri - t o th e tetramethy l lea d sal t wa s subsequentl y postulate dt o b e chemica l rathe r tha n biological , proceedin g vi aformatio n an d the n decompositio n o f a n organi c sulfid e inter mediate , (Me 3 Pb) 2 S. 9 5 Usin g asyste mcontainin g n o sulfides , however , othe r worker s showe dth e produc tio n b y microorganism s o f Me 4 P b fro mMe 3 P b + muc hi n exces s o f

yield s expecte dfro mth e stoichiometr y o f

redistributio n reaction s o f lea d alky l compound s in aqueou s solutions. 9 4 Thus , th e alkylatio n appear s t o b e direc t an dbiological . Th e alkylatio n o f

lead , unlik e tha t

o f mercury , wa s no t mediate db y methylcobalamin , a s show n whe n equimola r

amount s o f

Me 3 PbOAc , Me 3 PbCI , Me 2 PbCl 2 , an dPb(N0 3 ) 2 wer e substitute dfo r in organi c mercur y in a n aqueou s tes t syste m(~p H 7). 9 5 Taylo r

an dHanna, 9 6 however , hav e recentl y demonstrate dtha t

prolonge dincubatio no f methylcobalami n withafin e suspensio n o f lea dox id e (Pb 3 0 4 ) in a n aqueou s mediu mresult s in partia l demethylatio n o f

th e corrinoid . Thi s chemica l demethylatio n o f

MeB 1 2 b y Pb 3 0 4 wa s show n t o b e highl y p H dependent , wit hn o demethylatio n occur rin g at p H 7 , an d6 1 percen t occurrin g at

p H 2 . Trace r studie s wit h[ 14 C]-methyl-labele d methylcobalami n indicate dtha t demethylatio n o f MeB 1 2 b y Pb(IV ) wa s accompanie db y apro portiona l volatilizatio n o f th e label . Thes e result s ar e in agreemen t

wit hth e know n instabilit y o f monoalky l lea dcompound s in aqueou s medi aa s de scribe db y Wood. 9 7 Th e alkylatio n o f lead , then , unlik e tha t

o f merc ury , doe s no t

appea r t o resul t

in nonvolatile , toxi c organolea dtha t

coul dunderg o biomagnificatio n in th e foo dchain . Volatil e TM Lgenerate din situ woul db e expecte dt o escap e fro mabod y o f water . Th e possibl e uptak e o f tetramethy l lea db y aquati c organism s durin g it s passag e t o th e surfac e o f abod y o f wate r i s unknown . 6.4. 3 Plant s Lea di s transferre dfro mth e atmospher e t o th e soi l an dvegetativ e compartment s o f th e environ men t b y dr y an dwe t

deposition . Considerabl e atten tio n ha s bee n devote dt o determinin g th e amoun t an dlocalizatio nof

lea din roadsid e an dsmelte r areas , bu t

littl e informatio n i s availabl e regardin g it s chemistr y an deffect s inthos e areas . Mott o e l al. 9 8 suggeste dtha t

plan t uptak e i s probabl y relate dbet te r t o solubl e rathe r

tha ntota l lea dinsoils . Wilso n an dCline 9 9 conclude dtha t onl y 0.00 3 t o 0.00 5 per cen t o f tota l lea di

nsoi l i s availabl e fo r

plan t uptake . Th e soi l solutio ni s affecte dby al l th e reaction s tha t occu r a s th e constituent s ar e change dthroug haddi tio nt o o r

depletio n fro mth e soil . Ultimately , th e compositio no f

th e soi l solutio n i s controlle db y th e solubilit y o f

th e variou s minera l phase s in th e soil . Th e long-ter meffect s o f lea din soil s ar e uncertain . Onl y recentl y ha s attentio n bee ngive n t o th e solubilit y relationship s o f PbS0 4 , Pb 3 (P0 4 ) 2 , an d PbC0 3 a s possibl e controllin g mechanism s fo r th e amoun t o f lea din soils. 4 4 If

PbC0 3 i s involve da s a reactio n product , ther e i s th e possibilit y tha t soil s o f hig hpH , upo n becomin g acidic , coul dreleas e lea d at som e futur e time. 10 0 Th e questio no f chemica l identit y o f

lea dinplant s i s stil l largel y unanswered . Ham p an dZiegler 10 1 hav e suggeste dtha t lea dasso ciate dwithplan t

surface s innatur e ma y b e largel y lea dphosphate . Zimdahl, 10 2 citin g studie s con ducte da t Colorad o Stat e Universit y an dth e Univer sity o f Illinois , reporte dth e identificatio n o f lea d pyrophosphat e in bea n root s an dlea dorthophos phat e insoybea nroot . Th e result s o f late r solubilit y studie s o f

th e tw o compound s suggeste dtha t lea d pyrophosphat e shoul db e th e dominan t for min plants . Th e proces s b y whic hlea di s take n u p b y plants , whic hma y b e passive, 8510 3 i s favore dunde r condi tion s o f lo w soi l pH. 10 4 MacLea n e t al. 10 5 hav e sug geste dtha t

soi l managemen t

practice s suc ha s th e ad ditio n o f organi c matter , lime , an dphosphat e ma y b e appropriat e incontaminate dsoil s t o reduc e th e availabilit y o f

lea dfo r plan t uptake . The y foun dtha t th e concentratio ninoat s an dalfalf avarie dinversel y 6-2 3P.8 8

withp H an dorgani c matter , an dtha t additio n o f phosphat e reduce dth e uptak e o f lead ; the y sug geste dtha t

th e p H effec t

wa s du e t o repressio n o f lea dsolubilit y a t

th e highe r

p H values . Joh n an d Va n Laerhoven 10 6 foun dlittl e differenc e in uptak e b y oat s an dlettuc e whe n lea dwa s derive dfro m water-insolubl e lea dcarbonat e a s oppose dt o th e mor e water-solubl e lea dchlorid e o r nitrate . Henc e th e formatio n o f

lea dcarbonat e a s aresul t o f limin g woul dno t

explai n th e p H effect . Wor k a t th e Universit y o f

Illinoi s an dat

Colorad o Stat e University , cite db y Zimdahl, 10 2 ha s show n tha t uptak e b y severa l plan t specie s i s inversel y pro portiona l t o soi l lea dconten t an di s greates t

unde r condition s o f

lo w p H an dlo w phosphorus . Th e bind in g o r exchang e capacit y o f

soils , relate dt o organi c content , i s extremel y importan t a s adeterminan t

of lea davailabilit y t o plants . Chelatin g agent s ca n modif y th e uptak e an dpossibl y th e movemen t of heav y metal s b y plants , bu t th e relativ e importanc e o f natura l chelatin g substance s i s har dt o evaluat e a t thi s time. 10 2 Zimdahl, 10 2 citin g anumbe r o f studie s regardin g chelatio n o f lea dwithEDTA , conclude s tha t th e exten t

o f lea dmovemen t

withi n th e plan t

i s stil l unresolved . H e question s whethe r studie s with syntheti c an dhighl y ionize dchelatin g agent s suc ha s EDT A actuall y reflec t

wha t i s happenin g in nature . I n astud y conducte da t th e Universit y o f

Il linois 10 7 (cite db y Zimdahl 102 ) , it wa s show n tha t

th e root s o f hydroponicall y grow n cor n acquire dasur fac e lea dprecipitat e an dslowl y accumulate d crystallin e lea din th e cel l walls . Th e surfac e precipi tat e forme dquickl y an dindependentl y o f plan t ac tivity . Tw o compound s wer e postulate dbu t no t identified . Th e lea denterin g th e roo t wa s concen trate din som e bu t

no t al l dictyosom e vesicles . After precipitatio n ha doccurre din th e dictyosom e vesi cle , cell-wal l precursor s wer e adde dt o th e vesicl e b y appositio n o f

vesicle s o r

b y interna l secretion . A s th e lead-containin g crystal s grew , mor e cell-wal l materia l wa s added , s o tha t th e entir e vesicl e even tuall y move dt o th e peripher y o f th e cel l t o achiev e fusio n wit hth e cel l wall . Lea ddeposit s wer e thereb y concentrate da t

th e cel l wal l an dno t withi n mitochondri ao r

othe r organelles. 10 2 Althoug hthi s sequenc e of

event s wa s observe din th e roo t tips , deposit s wer e observe dthroughou t th e plant , an di t wa s suggeste dtha t

asimila r

proces s occurre din al l plan t tissues. 10 2 Th e depositio n o f

lea do n th e lea f

surface s of plant s wher e th e particle s ar e ofte n retaine dfo r lon g tim e period s mus t

als o b e considered. 3210810 9 Sev era l studie s hav e show n tha t plant s nea r

roadway s exhibi t

considerabl y highe r

level s o f

lea dtha n thos e farthe r away . I n mos t

instances , th e highe r con centration s wer e du e t o lea dparticl e depositio n o n plan t surfaces. 3 2 Studie s hav e show n tha t particle s deposite do n plan t

surface s ar e ofte n ver y difficul t t o remov e completel y b y simpl e washin g technique s considere dcharacteristi c o f th e treatmen t

tha t woul db e use din ahousehol dkitchen.IOS. I 10,11 1 Leave s wit hhair y surface s see mabl e t o retai n (an d attract ) particle s vi aa n electrostati c mechanism . Othe r type s o f

leave s ar e covere dwit hacuticula r wax sufficientl y stick y t o preclud e th e remova l o f particles . Thu s rainfal l doe s no t serv e a s aparticu larl y effectiv e mean s o f removin g th e deposite dpar ticles. 11 0 Animal s o r

human s consumin g th e leaf y portion s o f

suc hplant s ca n certainl y b e expose dt o highe r tha n norma l level s o f lead . Fortunately , a majo r fractio n o f

lea demitte db y automobile s i s deposite dinsid e atypica l highwa y right-of-way , s o at leas t par t o f thi s proble mi s alleviated . Th e particl e depositio n o n leave s ha s le dsom e in vestigator s t o stipulat e tha t lea dma y ente r

plant s throug hth e leaves . Thi s woul dtypicall y require , however , tha t

th e lea dparticle s b e dissolve db y con stituent s o f

th e lea f surfac e and/o r

converte dt o th e ioni c formvi acontac t withwater . Th e forme r possibilit y i s no t

considere dlikely , sinc e cuticula r waxe s ar e relativel y iner t chemically . Zimdah l an d Arvik 8 5 hav e show n in arathe r elegan t se t o f experi ment s tha t

entr y o f ioni c lea dthroug hplan t leave s i s o f minima l importance . B y usin g th e lea f cuticle s o f severa l type s o f

plant s essentiall y a s membranes , the y foun dtha t

eve n hig hconcentration s o f lea dion s woul dno t

pas s throug hth e cuticle s int o distille d wate r o n th e opposit e side . Th e result s o f

th e studie s discusse dabov e generall y indicat e th e following : 1 . Th e uptak e o f

lea db y plant s fro msoi l i s highl y dependen t

o n th e chemica l equilibri a prevalen t

in th e soi l in question . Th e uptak e ca n probabl y b e controlle dthroug htreat men t o f th e soi l wit hmaterial s (e.g. , lime , phosphat e fertilizers , etc. ) tha t affec t thes e chemica l equilibria . 2 . Althoug huptak e rate s ar e enhance da t lowe r soi l p H levels , th e majorit y o f th e lea dtake n u p remain s in th e plan t roots ; onl y smalle r fraction s ar e translocate dt o th e shoots . 3 . Depositio n an dretentio n o f lea dparticle s o n plan t surface s ca n serv e a s arout e o f anima l o r huma n exposur e t o automotiv e lead . Thu s crop s grow n nea r

source s o f

hig htraffi c 6-2 4

### shoul dprobabl y b e considere dsuspec t

unles s appropriat e safet

y precaution s ar e taken . 6. 5 REFERENCE S FO RCHAPTE R6 1 . Habibi , K . Characterizatio n o f particulat e matte r

in vehi cl e exhaust . Environ . Sci . Technol . 7(3):223-234 , 1973 . 2 . Te r Haar , G . L. , D . L . Lenane , J . N . Hu , an dM . Brandt . Composition , siz e an dcontro l o f automotiv e exhaus t

par ticulates . J . Ai r

Pollut . Contro l Assoc . 22(l):39-46 , 1972 . 3 . Ganley , J . T . an dG . S . Springer . Physica l an dchemica l characteristic s o f

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ignitio n engin e ex haust . Environ . Sci . Technol . S(4):340-347 , 1974 . 4 . Hirschler , D . A . an dL . F . Gilbert . Natur e o f lea din auto mobil e exhaus t

gas . Arch . Environ . Hlth . 8:297-313 , 1964 . 5 . Habibi , K. , E . S . Jacobs , W . G . Kunz , Jr. , an dD . L . Pastell . Characterizatio n an dcontro l o f gaseou s an dparticulat e exhaus t emission s fro mvehicles . Pape r presente dat

Th e Fift hTechnica l Meetin g o f th e Ai r Pollutio n Contro l As sociation , Wes t

Coas t Section . Oct . 8-9 , 1970 . 6 . Mueller , P . K. , H . L . Helwig , A . E . Alcocer , W . K . Gong , an dE . E . Jones . Concentratio n o f fin e particle s an dlea d in ca r exhaust . In: Symposiu mo n Ai r Pollutio n Measure men t Methods , Specia l Technica l Publicatio n No . 352 , America n Societ y fo r

Testin g an dMaterials . 1963 . 7 . Habibi , K . Characterizatio n o f particulat e lea din vehicl e exhaust—experimenta l techniques . Environ . Sci . Technol . 4(3):239-248 , 1970 . 8 . Habibi , K . Automotiv e particulat e emission s an dthei r control . Pape r

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th e join t

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Th e Societ y o f

Automotiv e Engineers , Mid-Michiga n Section , an dTh e America n Chemica l Society , Midlan dSection , Midland , Michigan . SA ETech . Pape r (710638) : 1-8 , 1970 . 9 . Lee , R . E. , R . K . Patterson , W . L . Crider , an dJ . Wagman . Concentratio n an dparticl e siz e distributio n o f particulat e emission s i n automobil e exhaust . Atmos . Environ . 5(4):225-237 , 1971 . 10 . Huntzicker , J . J. , S . K . Friedlander , an dC . 1 . Davidson . Materia l balanc e fo r

automobile-emitte dlea din Lo s Angele s Basin . Environ . Sci . Technol . 9(5):448-457 , 1975 . 11 . Robinson , E . an dF . L . Ludwig . Siz e Distributio n o f At mospheri c Lea dAerosol . Stanfor dResearc hInstitute , Menl o Park , Calif . SR I Projec t No . PA-4788 . Apri l 30 , 1964 . 12 . Cholak , J. , L . J . Schafer , an dD . Yeager . Th e ai r transpor t o f lea dcompound s presen t in automobil e exhaus t gases . J . Am . Ind . Hyg . Assoc . 29(6):562-568 , 1968 . 13 . Lee , R . E. , R . K . Patterson , an dJ . Wagman . Particle-siz e distributio n o f

meta l compound s in urba n air . Environ . Sci . Technol . 2(4):288-290 , 1968 . 14 . Flesch , J . P . Calibratio n studie s o f ane w sub-micro n aero so l siz e classifier . J . Colloi dInterfac e Sci . 29(3):502-509 , 1969 . 15 . Gillette , D . A . an dJ . W . Winchester . A stud y o f agin g o f lea daerosols.I . Observations . Atmos . Environ . 6(7):443-450 , 1972 . 16 . Lawther , P . J. , B . T . Commins , R . McK . Ellison , an dB . Biles . Mor e observation s o n airborn e lead . In: Proceed ing s o f th e Internationa l Symposiu mo n Environmenta l Healt hAspect s o f

Lead . Commissio n o f th e Europea n Communities , Luxembourg . 1973 . p . 373-389 . 17 . Chamberlain , A . C , W . S . Clough , M . J . Heard , D . Newton , A.N.B . Stott , an dA . C . Wells . Uptak e o f inhale d lea dfro mmoto r

exhaust . Postgrad . Med . J . J/:790-794 , 1975 . 18 . Fugas , M. , D . Majic , R . Paukovic , B . Wilder , Z . Skuric . Biologica l Significanc e o f Som e Metal s a s Ai r

Pollutants , Par t I : Lead . U . S . Departmen t o f Health , Educatio n an d Welfare , Publi c Healt hService , Consume r Protectio n an d Environmenta l Healt hService . 1974 . 8 5 p . 19 . Surve y o f

Lea din th e Atmospher e o f Thre e Urba nCom munities . U . S . Departmen t o f Health , Educatio n an d Welfare , Publi c Healt hService , Nationa l Ai r Pollutio n Contro l Administration , Washington , D . C . Pub . No . AP-12 . 1965 . 20 . Edwards , H . W . (ed.) . Environmenta l Contaminatio n Cause db y Lead . (Interi mreport. ) Prepare dunde r NS F grant s GI-34813X 1 an dGI-4442 3 b y Colorad o Stat e University , For t

Collins , Colo . 1974 . 21 . Laveskog , A . A metho dfo r determinin g tetramethy l lea d (TML ) an dtetraethy l lea d(TEL ) in air . In: Proc . o f th e Secon dInternationa l Clea n Ai r Congres s o f

th e Interna tiona l Unio n o f

Ai r Pollutio n Preventio n Associations , Washington , D . C . Academi c Press , Ne w York . Pape r CP-37D . 1971 . p . 549-557 . 22 . Harrison , R . M.,R . Perry , an dD . H . Slater . Th e contribu tio n o f organi c lea dcompound s t o tota l lea dlevel s i n ur ba n atmospheres . In: Proc . Int . Symposiu mo n Recen t Ad vance s in th e Assessmen t o f th e Healt hEffect s o f

Environ menta l Pollution . Vol . 3 . Commissio n o f th e Europea n Communities , Luxembourg . 1975 . p . 1783-1788 . 23 . Purdue , L . J. , R . E . Enrione , R . J . Thompson , an dB . A . Bonfield . Determinatio n o f organi c an dtota l lea din th e atmospher e b y atomi c absorptio n spectrometry . Anal . Chem . 45(3):527-528 , 1973 . 24 . Skogerboe , R . K . Analytica l chemistry . In: Environmenta l contaminatio n cause db y lead . Nationa l Scienc e Founda tion . 1975 . p . 187-203 . 25 . Te r Haar , G . L . an dM . A . Bayard . Compositio n o f air born e lea dparticles . Nature . 232:553-554/1971 . 26 . Pierrard , J . M . Photochemica l decompositio no f lea d halide s fro mautomobil e exhaust . Environ . Sci . Technol . i(l):48-5l , 1969 . 27 . Robbins , J . A . an dF . L . Snitz . Bromin e an dchlorin e los s fro mlea dhalid e automobil e exhaus t particles . Environ . Sci . Technol . 6(2):164-169 , 1972 . 28 . Dzubay , T . G . an dR . K . Stevens . Application s o f X-Ra y fluorescenc e t o particulat e measurements . In: Secon d Join t Conferenc e o n Sensin g o f Environmenta l Pollutants , Washington , D . C . Instrumen t Societ y o f

America , Pitts burgh , Penn . 1973 . p.2 1 1-216 . 29 . Olson , K . W . an dR . K . Skogerboe . Identificatio n o f soi l lea dcompound s fro mautomotiv e sources . Environ . Sci . Technol . 9(3):227-230 , 1975 . 30 . Barltrop , D . an dF . Meek . Absorptio n o f differen t

lea d compounds . Postgrad . Med . J . 57:805-809 , 1975 . 31 . Daines , R . H. , H . Motto , an dD . M . Chilko . Atmospheri c lead : it s relationshi p t o traffi c volum e an dproximit y t o highways . Environ . Sci . Technol . 4(4):318-322 , 1970 . 32 . Schuck , E . A . an dJ . K . Locke . Relationshi p o f automotiv e lea dparticulate s t o certai n consume r crops . Environ . Sci . Technol . 4(4):324-330 , 1970 . 33 . Tatsumoto , M . an dC . C . Patterson . Th e concentratio n o f commo n lea din se awater . In: Eart hScienc e an d Meteorites . Amsterdam , Nort hHolland . 1963 . p . 74-89 . 

### 6-2 5P.9 0

34 . Tatsumoto , M . an dC . C . Patterson . Concentration s o f commo n lea din som e Atlanti c an dMediterranea n water s an di n snow . Nature . 799(489 1 ):350-352 , 1963 . 35 . Chow , T . J . an dC . C . Patterson . Concentratio n profile s o f bariu man dlea din Atlanti c water s of f Bermuda . Eart h Planet . Sci . Lett . 7:397-400 , 1966 . 36 . Duce , R . A. , G . L . Hoffman , an dW . H . Zoller . At mospheri c trac e metal s a t remot e norther n an dsouther n hemispher e sites : pollutio n o r natural ? Science . 787(4171):59-61 , 1975 . 37 . Taylor , S . R . Abundanc e o f chemica l element s in th e con tinenta l crust : A ne w table . Geochim . Cosmochim . Acta . 25:1273-1285 , 1964 . 38 . Zoller , W . H. , E . S . Gladney , an dR . A . Duce . At mospheri c concentration s an dsource s o f trac e metal s a t th e Sout hPole . Science . 183: 198-200, 1974 . 39 . Robinson , E . an dR . C . Robbins . Emissions , Concentra tions , an dFat e o f

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Pollut . Contro l Assoc . 26(8):753-766 , 197 6 82 . Singer , M . J . an dL . Hanson . Lea daccumulatio nin soil s nea r highway s in th e Twi n Citie s metropolita n area . Soi l Sci . Soc . Amer . Proc . 33:152 , 1969 . 83 . Lagerwerff , J . V . an dD . L . Brower . Exchang e absorptio n o r precipitatio n o f

lea din soil s treate dwit hchloride s o f aluminum , calciu man dsodium . Soi l Sci . Soc . Amer . Proc . 37(1):11-13 , 1973 . 84 . Gadde , R . R . an dH . A . Laitinen . Studie s o f heav y meta l absorptio n b y hydrou s iro n an dmanganes e oxides . Anal . Chem . 46(13):2022-2026 , 1974 . 85 . Zimdahl , R . L . an dJ . H . Arvik . Lea din soil s an dplants : a literatur e review . Crit . Rev . Environ . Control . 3:213-224 , 1973 . 86 . Santillan-Medrano , J . an dJ . J . Jurinak . Th e chemistr y o f lea dan dcadmiu min soil : soli dphas e formation . Soi l Sci . Soc . Am . Proc . 39:851-856 , 1975 . 87 . Lovering , G . T . Lea din th e Environment . U.S . Geologica l Surve y Professiona l Pape r 957 . Washington , DC . 1976 . 9 0 p . 88 . Hem , J . D . an dW . H . Durum . Solubilit y an doccurrenc e o f lea di n surfac e water . J . AM . Wate r Work s Assoc . 65(8):562-568 , 1973 . 89 . Davies , P . H . an dW . H . Everhar . Effect s o f Chemica l Variation s i

n Aquati c Environments . Vol . III . Lea dTox icit y t o Rainbo w Trou t an dTestin g Applicatio n Factor . Concept . U.S . Environmenta l Protectio n Agency , Offic e o f Researc han dMonitoring , Researc hTriangl e Park , N.C . Pub . No . EPA-R3-73-011C . 1973 . 8 0 p . 90 . Hem , J . D . Geochemica l control s o f lea dconcentratio ni

n strea mwate r

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lead . Nature . 255(5505):217-218 , 1975 . 96 . Taylor , R . T . an dM . L . Hanna . Methylcobalamin : Methylatio n o f

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6-2 8

## 7 . ENVIRONMENTA L CONCENTRATION S AN D POTENTIA L EXPOSURE S 7. 1 AMBIEN T AI REXPOSURE S Severa l studie s o n concentration s o f lea din th e ambien t ai r hav e bee n undertaken . Thes e studie s wer e generall y intende dt o surve y th e level s an ddis tribution s o f

lea din th e genera l ai r

environmen t

an d aroun dsources . The y usuall y wer e no t designe din conjunctio n wit hepidemiologica l studie s o f th e con curren t effect s o f

lea do n ma n o r

othe r organisms . Ye t tha t i s th e contex t

in whic hthes e studie s mus t no w b e interprete dt o she dth e mos t ligh t possibl e o n th e concentration s likel y t o b e encountere din variou s environmenta l settings . Measurement s take n withhigh-volum e samplers , dust-fal l buckets , an dparticl e siz e fractionator s ar e include din thes e studies ; however , withth e excep tio n o f th e NAS N dat afro m197 0 throug h1974 , qualit y contro l an dinterlaborator y comparabilit y ar e unspecified . Th e effectivenes s o f som e filte r medi ain collectin g ver y smal l lead-containin g parti cle s ha s bee n questioned ; thi s subjec t i s discusse din Chapte r 4 . Th e studie s sho w that : 1 . Lea dtypicall y occur s in urba n airborn e sus pende dparticle s 0. 5 fim o r les s in mas s me dia n equivalen t

diamete r

a t annua l averag e concentration s rangin g fro m<0. 1 t o 5 /xg/m 3 , withan overal l averag e o f 1 t o 2 Mg/m 3

. 2 . Urba n concentration s o f lea dhav e decline d somewha t

sinc e 1970 . 3 . Suspende dparticle s in rura l ai r sample s con tai n lea dat

concentration s rangin g fro m <0.0 1 t o 1. 4 /ug/m 3 , withan overal l averag e o f abou t 0. 2 /j.g/m 3

. 4 . Monthl y averag e concentration s o f lea din urba n settleabl e particle s rang e fro m3 t o 1 2 mg/m 2 -mo . 5 . Indoo r

concentration s o f

lea dar e quit e variable , bu t

ar e generall y one - t o two-third s th e concentration s o f adjacen t

outdoo r levels . A discussio n o f

th e NAS N measurement s follows . Summarie s o f additiona l studie s ca nb e foun din Ap pendi x C . 7. 1 . 1 Nationa l Ai rSurveillanc e Networ k(NASN ) Dat a Sinc e 1957 , sample s o f

suspende dparticulat e mat te r collecte da t

som e 30 0 urba nan d3 0 nonurba n NAS N site s hav e bee nanalyze dfo r trac e metals , in cludin g lead . Onl y dat abeginnin g wit h196 6 ar e summarize dhere , however , becaus e th e procedur e use dbefor e 196 6 wa s foun dt o recove r onl y abou t

5 0 percen t o f th e lea dactuall y present . Th e emissio n spectrograph ^ metho dno w employe di n th e analysi s ha s sufficien t

sensitivit y t o permi t

detectio n o f lea dinal l urba n an dmos t nonurba nsamples . Summarie s o f

th e dat afo r

urba nan dnonurba n NAS N site s fo r

196 6 throug h197 4 ar e presente di n Table s 7- 1 an d7-2 , whic hcategoriz e th e site s b y fou r successiv e annua l averag e concentratio n ranges. ' 2 Th e majorit y o f th e urba nsite s (9 1 percen t of th e site-years ) reporte dannua l average s belo w 2. 0 Mg/m 3 , an dth e majorit y o f nonurba nsite s (8 6 per cen t o f th e site-years ) reporte dannua l average s belo w 0. 2 ,y,g/m 3

. Sample s collecte db y th e NAS N fro m197 0 throug h197 4 wer e combine dfo r analysi s int o quar terl y composites . Table s 7- 3 an d7-4 , respectively , giv e th e cumulativ e frequenc y distribution s o f urba n an dnonurba nquarterl y composit e value s fo r 197 0 throug h1974. ' Urba nNAS N site s fo r

whic hannua l averag e con centration s hav e bee n3. 0 figlm 3 o r greate r ar e liste d inTabl e 7-5. 1 2 Highes t concentration s fo r

shorte r interval s (quarterl y an d24-hr ) hav e bee n included , wher e available , inorde r t o indicat e th e variatio n in concentratio nwit haveragin g tim e an dpotentia l pea k exposur e conditions . A larg e numbe r o f Souther n Californi acitie s ar e include dinth e lis t becaus e o f

th e heav y automobil e traffi c in thes e areas . Bot hth e annua l averag e an dmaximu mvalue s at Lo s Angele s Count y site s wer e consistentl y high , 7- 1P.9 4

TABL E 7-1 . NUMBE R O F NAS N URBA N STATION S WHOS E DATA FAL L WITHI N SELECTE D ANNUA L AVERAG E LEA D CONCENTRATIO N INTERVALS , 1966-1974 1 • * TABL E 7-2 . NUMBE R O F NAS N NONURBA N STATION S

WHOS E DATA FAL L WITHI N SELECTE D ANNUA L AVERAG E LEA D CONCENTRATIO N INTERVALS , 1966-19741 2 Yea r 1966 : No . station s Percen t 1967 : No . station s Percen t 1968 : No . station s Percen t 1969 : No . station s Percen t 1970 : No . station s Percen t 1971 : No . station s Percen t 1972 : No . station s Percen t 1973 : No . station s Percen t 1974 : No . station s Percen t 1966-1974 : No . station s Tota l percen t < 0. 5 9 9 4 3 1 4 9 5 2 9 5

— 1 6 9 2 0 1 5 1 9 1 5 9 6 8 Concentratio n interval , ug 0.5-0.9 9 4 0 4 2 3 7 3 2 6 7 4 5 4 6 2 5 5 4 3 3 2 3 2 1 6 7 3 7 7 6 5 5 6 9 5 3 47 9 3 8 1.0-1. 9 4 0 4 2 6 3 5 5 5 4 3 6 10 3 5 7 8 0 5 0 6 4 5 8 8 4 4 7 3 6 2 6 3 8 2 9 56 2 4 5 2.0-3. 9 6 6 9 7 10 6 2 3 1 2 1 5 9 2 1 1 9 1 2 7 4 3 4 3 10 4 8 /m 3 4.0-5. 3

—

— —

0

0 0 6 1 Tota l 9 5 10 0 11 3 10 0 14 6 10 0 17 8 10 0 15 9 10 0 10 9oooO00o 13 7 10 0 13 0 10 0 124 7 10 0 Yea r

1966 : No . station s Percen t 1967 : No . station s Percen t 1968 : No . station s Percen t 1969 : No . station s Percen t 1970-1971 : No . station s Percen t 1972 : No . station s Percen t 1973 : No . station s Percen t 1974 : No . station s Percen t 1966-1974 : No . station s Tota l percen t < 0.0 3

— 1 5 1 5

—

— — 10 2 9 9 3 9 3 1 9 2 4 1 5 Concentratio n interva l 0.03-0.09 9 1 0 5 2 7 3 5 1 5 7 5 1 1 5 2

— — 4 1 2 7 3 1 5 3 1 5 9 3 6 0.10-0.1 9

6 3 2 10 5 0 4 2 0 9 4 3 7 7 0 9 2 6 6 2 6 6 3 8 5 7 3 5 ng'm 3

0.20-0.4 5 3 1 6 2 10

— — 1 5 3 3 0 1 1 3 3 1 4 2 1 2 2 3 1 4 Tota l 1 9 10 0 2 0 10 0 2 0 10 0 2 1 10 0 10 10 0 3 4 10 0 2 3 10 0 1 6 10 0 16 3 10 0 TABL E 7-3 . CUMULATIV E FREQUENC YDISTRIBUTION S O F QUARTERL YLEA D MEASUREMENT S ATURBA N STATION S B YYEAR , 197 0 THROUG H 1974 ' (/u.g/m3 )

Yea r 197 0 197 1 197 2 197 3 197 4 No .

quarterl y composite s 79 7 71 7 70 8 55 9 59 4 Mi n

LD " LD a LD » LD a 0.0 8 1 0

0.4 7 0.4 2 0.4 6 0.3 5 0.3 6 3 0 0.7 5 0.7 1 0.7 2 0.5 8 0.5 7 5 0 1.0 5 1.0 1 0.9 7 0.7 7 0.7 5 Percentil e

7 0 1.3 7 1.4 2 1.2 5 1.0 5 1.0 0 9 0 2.0 1 2.2 1 1.9 3 1.6 2 1.6 1 9 5 2.5 9 2.8 6 2.5 7 2.0 8 1.9 7 9 9 4.1 4 4.3 8 3.6 9 3.0 3 3.1 6 Max .

5.8 3 6.3 1 6.8 8 5.8 3 4.0 9 Arithmeti c

Mea n 1.1 9 1.2 3 1.1 3 0.9 2 0.8 9 Std .

dev . 0.8 0 0.8 7 0.7 8 0.6 4 0.5 7 Geometri c Std . Mea n dev . 0.9 9 1.8 4 1.0 0 1.8 9 0.9 3 1.8 7 0.7 6 1.8 7 0.7 5 1.8 0 a L D = limi t o f detection .

TABL E 7-4 . CUMULATIV E FREQUENC YDISTRIBUTION S O F QUARTERL YLEA D MEASUREMENT S

ATNONURBA N STATION S BYYEAR , 197 0 THROUG H 1974 '

(ng/m 3 )

197 0 197 1 197 2 197 3 197 4 12 4

8 5 13 7 10 0 7 9 0.00 3

0.00 3 0.00 7 0.01 5 0.00 7 0.00 3 0.00 3 0.00 3 0.00 3 0.26 7 0.38 3 0.62 8

0.00 3 0.00 3 0.00 3 0.00 3 0.12 7 0.20 4 0.78 3 0.00 7 0.00 7 0.10 7 0.16 6 0.29 4 0.39 2 0.95 0 0.01 5 0.01 5 0.05 8 0.13 2 0.23 3 0.39 2 0.69 8 0.00 7 0.05 3 0.08 7 0.14 1 0.22 1 0.31 7 0.49 6 1.47 1 1.13 4 1.04 8 0.93 9 0.53 4 0.08 8 0.19 0

0.04 7 0.15 5 0.13 9 0.16 9 0.11 0 0.14 9 0.11 1 0.11 1 Yea r N o

quarterl y composite s Mi n 1 0 3 0 5 0 Percentil e 7 0 9 0 9 5 9 9 Max . Arithmeti c Std . Mea n dev . Geometri c Std . Mea n aev . 0.04 0 3.72 0.00 8 4.8 0 0.09 0 2.5 9 0.06 8 2.77 0.08 3 2.3 0 7- 2TABL E 7-5 . NAS N STATION S WIT H ANNUA L AVERAG E LEA D CONCENTRATION S 23. 0 Mg/m 31 < 2 Yea r an d statio n 1966 : Phoenix , Ariz . Burbank , Calif . Lo s Angeles , Calif . Pasadena , Calif . 1967 : Lo s Angeles , Calif . 1968 : Burbank , Calif . Glendale , Calif . Lon g Beach , Calif . Lo s Angeles , Calif . Pasadena , Calif . 1969 :Fairbanks , Alask a Phoenix , Ariz . Burbank , Calif . Glendale , Calif . Lo s Angeles , Calif . Sa n Juan , Puert o Ric o Dallas , Tex . 1970 : Burbank , Calif . Glendale , Calif . Lo s Angeles , Calif . Sa n Juan , Puert o Ric o Dallas , Tex . 1971 : Anaheim , Calif . Burbank , Calif . Sant a Ana , Calif . Lo s Angeles , Calif . 1972 : Burbank , Calif . Glendale , Calif . Lo s Angeles , Calif . Sa n Juan , Puert o Ric o 1973 : Burbank , Calif . Averag e 3. 2 3. 7 3. 6 3. 6 3. 1 4. 4 3. 0 3. 3 3. 9 3. 5 3. 2 3. 1 3. 5 3. 1 4. 6 3. 8 3. 0 4. 9 3. 5 4. 5 3. 7 3. 2 3. 3 5. 3 3. 5 4. 6 3. 2 3. 5 3. 1 5. 0 4. 0 Maximu m

Quarterl y composite 8. 1 6. 0 11. 0 4. 3 5. 4

— — — — — 4. 8 7. 1 4. 7 4. 5 5. 7 4. 2 5. 2 5. 8 4. 2 5. 6 4. 1 3. 8 4. 0 6. 2 4. 6 6. 3 6. 7 5. 2 4. 8 6. 9 5- 2 24-h r

— ' ' — — —

— 14. 0 7. 5 12. 0 10. 0 8. 3

— — — — — — —

— — — — —

— — — —

— — — —

— apparentl y becaus e o f location , topography , an d meteorologica l condition s tha t favo r retentio n o f pollutant s in th e ai r

ove r th e area . Ambien t particulat e lea ddat afro mNAS N wer e studie dfo r

trend s ove r

th e 10-year

perio dfro m 196 5 throug h1974 . Figur e 7- 1 show s th e 10th , 50th , an d90t hpercentile s fo r dat afro m9 2 NAS N urba n sites. 3 Urba n lea dconcentration s a s describe db y th e 50t hpercentile s increase dfro m196 5 unti l 197 1 an d the n decline dfro mabou t 1. 1 ,ug/m 3 t o 0.8 4 /xg/m 3 —abou t

a24-percen t

decrease , wit hmos t

o f thi s declin e occurrin g betwee n 197 2 an d1973 . Th e othe r percentile s exhibi t

asimila r

pattern . Thi s genera l patter n describe s th e tren dfo r mos t o f th e site s studied . Trend s in th e percentag e o f lea dinth e tota l particulat e matte r measure dals o follo w thi s pattern , whic hindicate s tha t th e trend s in lea dar e no t jus t aresul t o f genera l particulat e control s bu t ar e adirec t

resul t o f decrease s inlea demissions .

E • a \ —i—i—i—i—i—r

90T H PERCENTIL E

Figur e 7-1 . Seasona l pattern s an d trend s I n quarterl y averag e urba n lea d concentrations. 3 Th e seasona l patter n in quarterl y composit e value s (soli dline s inFigur e 7-1 ) show s tha t th e high es t level s o f

airborn e lea doccurre di nth e winte r quarter s (firs t

an dfourth ) an dth e lowes t level s in th e summe r

quarter s (secon dan dthird) . I n contrast , automotiv e emission s o f lea dwoul db e expecte dt o b e greate r

in th e summe r

fo r tw o reasons : (l ) gasolin e usag e i s highe r inth e summer , an d(2 ) lea d conten t i s raise di

nsumme r

gasoline s t o replac e som e o f th e mor e volatil e high-octan e component s tha t canno t b e use din summertim e gasolines . Evi dentl y summertim e meteorologica l condition s ex pedit e th e movemen t

o f thes e large r

emission s mor e quickl y an dwidel y throug hth e atmospher e o nthei r wa y t o subsequen t

destination s invegetation , crops , soil , an dwater . Sinc e abou t

th e 197 0 mode l year , automobile s hav e bee nbuil t

wit hlower-compressio n engine s tha t ca nus e lower-octan e gasolin e an dthu s gasolin e with lowe r lea dcontent . A s aresul t o f thi s engin e modification , practicall y al l car s buil t sinc e 197 0 ar e abl e t o us e regula r

gasolin e instea do f

th e mor e leade dpremiu mfuels . Figure s 7- 2 an d7- 3 show , respectively , th e percentag e o f th e total , marke t

fo r regula r an dpremiu mgasoline s an dth e tren dinlea d conten t o f gasolines. 4 Th e result s o f th e engin e modification s ca nb e clearl y see ninth e lowe r lea d conten t ingasolin e (bot hinregula r an dpremiu m grades ) an din th e subsequen t increas e inregula r gasolin e sale s an ddecreas e in premiu msales . Thes e 7- 3P.9 6

factors , couple dwithth e us e o f amodes t

amoun t o f low-lea dan dno-lea dgasolin e introduce dat abou t thi s sam e time , ar e identifie da s principall y responsi bl e fo r th e observe ddecreas e in ambien t lea dcon centration s ove r

thi s period . Th e increasin g us e of unleade dgasolin e resultin g fro mEP A regulations , whic hi s reflecte din Figur e 7-2 , will lea dt o eve n lowe r level s o f

atmospheri c pollutio n in th e future . Th e effec t

o f thes e change s i s enoug ht o overrid e th e genera l increas e in annua l gasolin e consumptio no f abou t 5 percen t

typica l o f

recen t year s (excep t 1974) . Thi s increas e in gasolin e consumptio n proba bly doe s no t

proportionatel y affec t man y urba n monitorin g site s (whic har e chiefl y center-cit y loca tions ) becaus e thei r

neighborhood s ar e generall y at o r nea r traffi c saturation . Ther e ma y eve n b e in stance s o f

areductio n in vehicl e mile s travele din downtow n area s becaus e o f ca r pooling , improve d mas s transi t

systems , an dth e los s o f busines s activit y t o suburba n shoppin g centers .

O 3 0 I z U J U F . 2 0 I I I I I I I I I I I I I I I I

REGULA R GA S SALE S 1% ) 

# f PREMIU M GA S SALE S 1% )

UNLEADE D GA S SALE S (% l _ 6 2 6 4 6 6 6 8 7 0 7 2 7 4 7 6 Figur e 7-2 . Nationwid e trend s I n regular , premium , an d unleade d gasolin e sales , 1960-1976. 4 I n additio n t o th e NAS N study , anumbe r o f othe r studie s involvin g majo r citie s an drura l area s hav e bee n undertaken . Thes e dat asuppor t th e NAS N result s (se e Appendi x C) . 7.1. 2 Airborn e Particl e Siz e Distributio n I n 1970 , acascad e impacto r networ k wa s estab lishe db y EP A in si x citie s (Cincinnati , Chicago , Denver , Philadelphia , St . Louis , an dWashington , D.C. ) t o collec t

particulate s o f

differen t siz e range s fo r subsequen t

analysi s fo r

lea dan dothe r

metals. 5 Th e samples , collecte donc e ever y 2 week s fo r aful l I l I I I l l 6 0 6 2 6 4 6 6 7 0 7 2 7 4 7 6 Figur e 7-3 . Nationwid e trend s I n lea d conten t o t regula r an d premiu m gasoline , 1960-1976. 4 year , wer e analyze dfo r siz e distribution . Sample s fro meac hcit y wer e als o composite dquarterl y an d analyze dfo r

lea db y optica l emissio n spectroscopy . Th e averag e annua l tota l lea dconcentratio n a s determine din thi s stud y range dfro mahig hquarte r o f 3. 2 jLtg/m

3 in Chicag o t o alo w quarte r o f 1. 3 /ng/m 3 in Washington , D.C . Th e averag e mas s me dia n diamete r

fo r lea dparticle s range dfro m0.6 9 fim inSt . Loui s t o 0.4 2 fim in Washington , D.C . Fifty-nin e t o 7 4 percen t o f th e lea dwa s associate d withparticle s smalle r

tha nI fim in diameter . Quar terl y an dannua l particl e siz e distributio ndat aar e presente din Tabl e 7-6 . 7.1. 3 Vertica l Gradient s o f Lea d i n th e At mospher e Ver y few studie s hav e bee nconducte dt o deter min e th e variatio n o f

lea dconcentration s wit hheigh t abov e th e ground . O f

thos e tha t

wer e found , al l con taine dth e premise , eithe r explicitl y o r

implicitly , tha t th e concentration s bein g studie dderive dprin cipall y fro mautomotiv e emissions . O f th e studie s foun dinth e literature , non e wer e adequatel y designe dt o establis hth e lea dconcentratio n versu s heigh t relationship . Suc hastud y woul drequir e simultaneou s measuremen t (preferabl y continuous ) at give nheigh t

interval s ove r

alon g perio do f

tim e ( aminimu mo f

l year) . Eve nthen , th e result s woul d b e vali donl y fo r

alocatio n havin g th e sam e charac teristic s an dexperiencin g th e sam e atmospheri c con ditions . A singl e se t

o f concentratio n value s ob taine dove r

shor t an dvariabl e tim e interval s i s no t sufficien t t o dra w conclusion s regardin g genera l ex posur e conditions . 7-4TABL E 7-6 . QUARTERL YAN D ANNUA L SIZ E DISTRIBUTION S O F LEAD-BEARIN G PARTICLE S FO R SI X CITIES . 1970

S TABL E 7-7. LEA D I N AI R O N MAI N STREET , BRATTLEBORO , VERMONT , SEPTEMBE R 12an d 13,1972» «

(ng/m3 )

Cit yan d quarte r o f yea r Averag e

concentration . jj.g/m 3 Averag e

mas s media n diameter . utr\ Chicago , III. : 1 2. 9 2 3. 5 3 3. 5 4 2. 9 Tota l yea r3. 2 Cincinnati , O. : 1 1. 0 2 2. 2 3 1. 9 4 2. 1 Tota l yea r1. 8 Denver , Colo. : 1 2. 0 2 1. 1 3 1. 4 4 3. 0 Tota l yea r1. 8 Philadelphia , Penn. : 1 1. 5 2 1. 2 3 1. 8 4 1. 9 Tota l yea r1. 6 St . Louis , Mo. : 1 1. 9 2 1. 6 3 1. 8 4 1. 8 Tota l yea r1. 8 Washington , D.C : 1 1. 3 2 1. 0 3 1. 3 4 1. 8 Tota l yea r1. 3 1.4 3 0.5 1 0.5 6 0.5 4 0.6 8 0.2 5 0.4 1 0.5 4 0.6 5 0.4 8 0.4 3 0.5 8 0.5 2 0.5 6 0.5 0 0.3 6 0.3 8 0.7 0 0.4 5 0.4 7 0.4 6 0.6 3 0.7 8 0.9 5 0.6 9 0.3 6 0.3 9 0.4 1 0.5 4 0.4 2 Percentag e

o f particle s 5//. m 4 1 6 5 6 5 6 4 5 9 7 9 7 4 6 9 6 7 7 2 7 6 6 8 6 9 6 6 7 0 7 4 7 4 6 2 7 0 7 0 6 8 6 3 5 9 5 3 6 2 7 6 7 3 7 4 7 1 7 4 Darro w an dSchroeder 6 measure dlea dconcentra tion s a t eigh t height s abov e stree t

leve l in Brat tleboro , Vermont . Th e value s foun dar e show n in Tabl e 7-7 . Th e averag e traffi c flo w wa s reporte dt o b e 750 0 car s pe r

day . Th e concentratio n level s show n in Tabl e 7- 7 ar e considerabl y highe r tha n thos e usuall y reporte din othe r cities . Th e investiga tor s attribute dth e highe r value s t o greate r

collectio n efficiency an dlowe r

samplin g heights , bu t

thi s wa s no t confirmed . Th e samplin g time s wer e shor t an d variable . Genera l conclusion s regardin g th e rela tionshi p o f

concentration s versu s heigh t canno t b e draw n fro mthes e data . Samplin g time s Heigh t abov e 8:36a.m . 10:2 0 a.m . 1:20p.m . street , f t 10:1 5 a.m . 12:0 0 noo n 3:0 0 p.m . 3:2 5 p.m . 4:3 5 p.m . 9/1 2 4:2 5 p.m . 1:02 p.m . 9/1 3 1 " 2 3 4 5 C 7 8 3 0 8.9 4

8.2 2 7.1 5 7.8 4

4.4 0 8.1 5 3.8 5

5.3 1 7.5 6 17.3 8

21.1 1 2.4 0 3.0 1

4.2 5 a Averag e ai rlea d valu e fo r54.3 8 m 3 ai r= 8.5 4 ^ g Pb/m 3

. D 1- . 2- , 3- . an d 4-ft heights : Averag e ai rlea d value s lo r13.5 3 m 3 ai r= 8.0 1 M 9 Pb/m 3

. c5- . 7- , 8- , 30-ft heights : Averag e ai rlea d value s fo r40.8 5 m 3 ai r= 3.9 6 n g Pb/m 3

. Edwards 7 ha s reporte dmeasurement s mad e in downtow n For t

Collins , Colo . Measurement s wer e mad e inastree t

canyo n forme db y two - an dthree stor y building s (averag e height , 9 m) . Wit ha2. 3 m/se c win dfro mth e Northeas t (stree t runnin g north-south) , lea dconcentration s alon g th e eas t sid e o f th e stree t

canyo nrange dfro m11. 3 /i,g/m 3 a t stree t leve l t o 4. 0 /u,g/m 3 a t

roo f level . O n th e wes t

sid e o f th e street , concentration s range dfro m0. 9 /ug/m 3 at stree t leve l t o 1. 3 /xg/m 3 at

roo f level . Value s fo r

tw o additiona l samplin g point s abov e th e rooftop s o n eac hsid e o f

th e stree t

wer e 0. 4 ttg/m 3 (eas t

side ) an d 0. 9 /xg/m 3 (wes t

side) . Lea dconcentration s 2 t o 5 block s awa y range dfro m0. 1 t o 0. 3 Mg/m 3

. Thes e dat areflec t

th e wid e variabilit y tha t ca nb e expecte d inurba ntraffi c environments . Unde r moderat e cross-win dconditions , concentration s withi n th e canyo n wer e strikingl y anisotropic , an dstreet-leve l concentration s alon g th e upwin dbuildin g face s wer e substantiall y highe r

tha nalon g th e downwin dface . Wit hdifferen t

win dregimes , differen t buildin g con figuration , an ddifferen t stabilit y conditions , th e dis tributio n o f

concentratio nvalue s woul dals o b e different . Barltro p an dStrelow 8 conducte da n ai r samplin g progra mat

apropose dnurser y sit e unde r a n ele vate dmotorway . Th e heigh t o f th e motorwa y wa s 9. 3 m . Ai r

sampler s wer e operate da t fiv e t o seve n site s fro mMonda y t o Friday , 8 a.m . t o 6 p.m . fo r 1 year . Th e maximu mindividua l valu e observe dwa s 1 8 /xg/m 3

. Th e 12-mont hmea nrange dfro m1.5 1 Mg/m 3 t o 1.3 5 /xg/m 3 , wit hstandar ddeviation s o f 0.9 1 an d0.66 , respectively . Th e author s reporte d tha t th e airborn e concentration s wer e independen t o f heigh t fro mgroun dleve l u p t o 7 m . PedCo-Environmental 9 measure dlea dconcentra tion s a t height s o f

5 an d2 0 f

t a t site s nea r

street s in 7- 5P.9 8

Kansa s City , Mo . an dCincinnati , O . Th e samplin g site s in Kansa s Cit y wer e describe da s unsheltered , unbiase db y localize dpollutio n influences , an dno t immediatel y surrounde db y larg e buildings . Th e Cincinnat i stud y are awa s locate din aprimaril y resi dentia l are awit hon e commercia l street . Sampler s wer e operate dfo r

24-h r period s fro m8 a.m . t o 8 a.m. ; bu t afew 12-h r

sample s wer e collecte dfro m8 a.m . t o 8 p.m . Dat awer e obtaine da t Kansa s Cit y o n 3 5 day s an da t

Cincinnat i o n 3 3 days . Th e rang e an d averag e value s reporte dar e show n in Tabl e 7-8 . I n al l case s excep t

two , th e measure dconcentration s wer e highe r

at 5 f t tha n a t 2 0 ft . Not e tha t

th e differenc e betwee n th e eas t sid e an dwes t

sid e o f th e street s wa s approximatel y th e sam e a s th e differenc e betwee n 5 an d2 0 f

t in height . TABL E 7-8 . AIRBORN E LEA D CONCENTRATION S AT5 - AN D 20-F TELEVATION S ABOV E STREE TLEVEL *

( M g/m3 )

Locatio n Rang e Kansa s Cit y0.8-4. 0 Cincinnat i 0.1-4. 6 Eas t sid e o f stree t 2 0 f t 5 ft Did . 1. 7 2. 0 0. 3 0. 9 1. 4 0. 5 Average s Wes t sid e o f stree t 2 0 I t 5 ft Diff . 1. 5 1. 7 0. 2 0. 6 0. 8 0. 2 Thes e dat areflec t

th e stron g influenc e o f th e geometr y o f

th e boundar y layer , wind , an dat mospheri c stabilit y condition s o n th e vertica l gra dien t o f lea dresultin g fro mautomobil e emissions . Th e varabilit y o f

concentratio n withheigh t i s furthe r complicate db y elevate demission s (i.e. , fro m stacks) . Concentration s measure dfro msamplin g station s o n th e roofs o f

building s severa l storie s hig h ma y no t reflec t actua l huma n exposur e conditions , bu t neithe r woul dasingl e samplin g statio n locate d at groun dleve l in abuildin g complex . Th e heigh t variatio n in concentratio n resultin g fro mvertica l diffusio n o f

automobil e emission s i s likel y t o b e smal l compare dt o tempora l an dspatia l variation s resultin g fro msurfac e geometry , wind , an dat mospheri c conditions . 7. 2 MOBIL E SOURC E EXPOSURE S Severa l majo r

studie s hav e bee n undertake n t o determin e th e lea dlevel s in th e ai r an din settle d dus t nea r bus y highway s tha t

ar e fa r fro man y sta tionar y lea dsource . Amon g th e mos t intensiv e o f thes e studie s wa s th e Lo s Angele s Catalys t Stud y o f 1974-1975 , undertake n b y EP A t o measur e th e im pac t o f th e catalyti c converte r o n ai r qualit y nea r

a majo r traffi c lea dsource. 1 0 , Tabl e 7- 9 summarize s th e 24-h r ambien t

con centration s o f

lea dobserve dat

tw o site s ( A an dC ) o n opposit e side s of amajo r

freewa y durin g th e calenda r yea r 1975 . I nadditio nt o th e monthl y averag e concentratio na t eac hsite , th e monthl y averag e cross-freewa y differenc e in concentration s (C-A ) an drati o o f

concentration s (C/A ) ar e show n inth e table . Finally , th e percentag e o f hour s in th e mont hwhe n wind s wer e fro mth e directiona l secto r tha t i s mos t favorabl e t o th e detectio no f cross-free wa y difference s i s show n in th e righthan dcolumn . Th e favorabl e win ddirectio ninterva l i s approx imatel y 160 ° t o 290 ° an dwa s define do n th e basi s o f concentratio n o f

carbo n monoxide , whic hi s atrace r fo r mobile-sourc e pollutants . TABL E 7-9 . MONTHL YAVERAG E LEA D CONCENTRATION S FO R 197 5 LO S ANGELE S CATALYS TSTUDY' "

Mont h Sit e A . Mg/m 3 SiteC .

jjg/m J Difference .

C- A Ratio .

C/ A % Favorabl e win d direction 8 Januar y February Marc h Apri l Ma y Jun e Jul y Augus t Septembe r Octobe r Novembe r 6. 0

4. 1 3. 2 2. 8 1. 8 1. 4 1. 9 2. 8 3. 7 4. 2 4. 8 6. 2 4. 8 5. 2 6. 0 7. 4 8. 1 8. 0 8. 4 8. 5 7. 3 6. 6 0. 2

0. 5 2. 0 3. 3 5. 6 6. 8 6. 1 5. 7 5. 0 3. 3 1. 7 1.0

3 1.1 8 1.6 3 2.1 4 4.0 6 5.6 8 4.2 7 3.0 0 2.3 0 1.7 4 1.3 7 28. 2 35. 2 43. 3 47. 6 65. 6 71. 2 68. 0 61. 6 59. 5 49. 4 31. 6 8 Fro m At o C ( S + SW + W winds) . A ver y stron g seasona l effec t i s observe din th e data , withconcentration s a t Sit e C exceedin g thos e at Sit e A b y onl y 3 percen t inJanuary , increasin g t o amaximu mdifferenc e o f ove r 40 0 percen t

in June , an dsubsequentl y decreasin g durin g th e fal l month s (n o dat awer e collecte ddurin g th e mont ho f Decem ber) . A s expected , ther e i s astron g linea r relation shi p betwee nth e occurrenc e o f favorabl e win d directio n an dth e observe dcross-freewa y differenc e inlea dconcentration . Th e correlatio n coefficien t betwee n th e tw o variable s i s 0.96 , indicatin g tha t almos t al l o f th e variatio n inth e cross-freewa y con centratio no f

lea dma y b e accounte dfo r b y th e seasona l variatio nin th e occurrenc e o f favorabl e win ddirection . I nastud y conducte dinLondon , England, 1 1 am bien t ai r level s o f organi c lea dwer e measure da t ur ba n sites . Concentration s o f 0.0 4 t o 0.1 1 M

g organi c Pb/m 3 wer e foun do n street s o f varyin g width s an d traffi c flow . Thes e value s wer e 0. 3 t o 2. 6 percen t o f tota l airborn e lead . Th e leve l o f organi c lea dinsid e abus y tunne l wa s 0.0 2 figlm 3 , o r 0. 1 percen t

o f th e tota l airborn e lead . No t surprisingly , organi c lea d concentration s measure dat abus y servic e statio n 7- 6

### range dfro m0.2 1 t o 0.5 9 figlm 3 

### , o r 3. 9 t o 9. 7 per cent o f tota l airborn e leada

t that site . A t ales s busy servic e station , th e concentratio n o f organi c lea

d was 0.0 7 Mg/m3



### . o r



### 4. 2 percent

o f tota l airborn e lead a t that site . Dat aobtaine di

n anumber

o f othe r studie s on lea di n dust s nea

r roadway s ar e summarize di n Ta ble s 7-1 0 and7-11 . Th e abov e dat ademonstrat e tha t abnormall y highconcentration s o f leadar e foundi

n th e ai r an ddus t nea r majo r roadways , an dtha t

peo pl e who liv e o r

wor k (e.g. , traffi c policemen , servic e statio n an dgarag e attendants ) i n thes e area s ar e ex posedt o hig

hleadconcentrations . Fo r comparison , Tabl e 7-1 2 summarize s lea di n dust s fro mnominall y residential urban areas . Thes e concentration s hav e awider rang e than thos e i

n traffic-oriente ddus t

samples . They are higher i n th e vicinit y o f a n identifie dpoint

sourc e suc

ha s th e E

l Pas o smelter , but

th e majorit

y o f th e reading s are lowe r than thos e o

f th e traffic-oriente dsamples . 7 3 POIN T SOURCE EXPOSURE S Severa l studie s hav e bee

n undertake n t o investig ate lea dlevel s i n th e vicinit

y o f variou s point

source s o f lea demissio n suc

has smelter s or

battery plants . B y fa r th e mos t complete an dinformativ e studie s are TABL E 7-10 . LEA D DUS TO N AN D NEA R HEAVIL Y TRAVELE D ROADWAY S Samplin g sit e Washington , DC : Bus yintersectio n Man ysite s Chicago : Nea rexpresswa y Philadelphia : Nea rexpresswa y Brooklyn : Nea rexpresswa y Ne wYor k

City : Nea rexpresswa y Detroit : Stree t dus t Philadelphia Gutte r(lo wexposure ) Gutte r(lo wexposure ) Gutte r(hig h exposure ) Gutte r(hig h exposure ) Miscellaneou s U.S . Cities : Highway s an d tunnel s Netherlands : Heavil ytravele d road s Concentratio n ji g Pb/ g 1282 0 (4000-8000)1 2 660 0 (3000-8000)1 3 (900-4900)1 " 20001 5 (966-1213)1 6 150 7 (270-2626) " 326 2 (280-8201)1 ' (10000-20000)1 8 50001 9 TABL E 7-11 . LEA D CONTEN TI N O R O N ROADSID E SOI L AN D GRAS S A S A FUNCTIO N O F DISTANC E FRO M TRAFFI C AN D GRAS S DEPT H I N PROFILE * Sit e an d distanc e fro m road , m Lea d content , iig/ g dryweigh t Gras s 0- 5 c m

soi l deat h 5-1 0 c m

soi l deDt h 10-1 5 c m

soi l dent h Wes t o t U.S . 1 , nea rPlan t Industr yStation , Beltsville , Md. : 8 1 6 3 2 Wes t o f southboun d lanes , Washington-Baltimor e Parkway , Bladensburg.Md. : 8 1 6 32 Wes t o f Interstat e 29 , Platt e City , Mo. : 8 1 6 32 Nort h o f Seymou rRoad , Cincinnati , O. : 8 1 6 3 2 68. 2 47. 5 26. 3 52 2

37 8 16 4 46 0

26 0 10 8 41 6

10 4 6 9

51. 3 30. 0 18. 5

21. 3 12. 5 7. 5

31. 3 26. 0 7. 6 54 0

20 2 14 0 24 2 14 0 6 1 15 0 10 1 5 5 30 0

10 5 6 0 11 2 10 4 5 5 2 9 1 4 1 0 9 8

6 0 3 8 9 5 6 6 6 0 1 1 8. 2 6. 1 a Adapte d fro m Lagerwerf f an d Spech t (cite d i n Referenc e 20) . 7-7P.10 0

TABL E 7-12 . LEA D DUS TI N RESIDENTIA L AREA S

Samplin g sit e Concentration , M 9 Pn/ g Philadelphia : Classroo m Playgroun d Windo wframe s Bosto n an d Ne wYork : Hous e dus t Brattleboro , Vt. : I n hom e Birmingham , England : I n hom e Ne wYor k

City : Middl e clas s residentia l E l Paso , Texas , Smeltertow n dus t at : 0- 1 mil e 1- 2 mile s 2- 3 mile s > 4 mile s Philadelphia : Urba n industria l Residentia l Suburba n 200 0 300 0 17501 ? (1000-2000) 2 1 (500-900) 6 50001 " (608-742)1 5

3685 3 (2800-103750)2 2 272 6 (100-84000)2 2 223 4 (100-29386)2 2 215 1 (200-22700)2 2 385 5 (929-15680)2 3 61 4 (293-1030)2 3 83 0 (277-1517)2 3 thos e carrie dou t

b y Yanke l e t

al. 2 4 an dLandriga ne t al. 2 5 in th e neighborhoo do f asmelte r

in Silve r Valley , Idaho . Consequently , th e dat afro mthes e studie s wil l b e describe dher e in som e detail . Othe r studie s carrie dou t

in Solan o County , Calif. ; Omaha , Neb. ; E l Paso , Tex. ; Helen aValley , Mont. ; Missouri ; Helsinki , Finland ; Mez aRive r Valley , Yugoslavia ; an dOntario , Canada , ar e summarize d in Appendi x C . Thei r

finding s ar e in substantiv e agreemen t

wit hthos e o f

th e Idah o study . Yanke l an dvo n Lindern 2 4 define dfiv e stud y area s arrange dconcentricall y aroun dth e smelte r an dtw o contro l areas . Are a1 consiste do f home s withi n 1 mil e o f

th e smelter ; Are a2 , 1 t o 2-1/ 2 mile s fro msmelter ; Are a3 , 2-1/ 2 t o 6 miles ; Are a4 , 6 t o 1 5 miles ; an dAre a5 , 1 5 t o 2 0 miles . Environmenta l samples , includin g surfac e soil , hous e dust , paint , grass , an dgarde n vegetable s wer e collecte da t th e home s in eac harea , a s wer e bloo dsample s fro mth e residen t childre n age d1 t o 9 years . Th e mea nlea d level s foun dinth e ambien t air , soil , an dhous e dus t al l decrease dwithincreasin g distanc e fro mth e smelter . A s mentione dinChapte r 12 , th e bloo dlea d level s o f th e residen t

childre nfollowe dasimila r pattern . Ambien t ai r lea dlevel s wer e measure db y high volum e sampler s statione dthroughou t th e Silve r Valley . A highl y significan t relationshi p betwee n distanc e fro mth e smelte r an dambien t

ai r lea dcon centratio n wa s found , an dthi s relationshi p wa s use d t o estimat e th e ambien t ai r lea dleve l fo r

an y loca tio ninth e stud y area . Th e mea nannua l ambien t ai r lea dlevel s nea r

asmelte r

fo r tw o differen t

year s (1974 , 1975 ) ar e show n graphicall y inFigur e 7-4 . Simila r result s wer e obtaine dfo r th e lea dconten t

o f soi l an dhous e dust . A s note din Chapte r 12 , th e children' s bloo dlea dlevel s correlat e quit e closel y withambien t

ai r lea dlevels , althoug hthi s resul t shoul dno t

b e interprete da s suggestin g tha t direc t inhalatio n o f

lea di s th e principa l exposur e mechan is minvolved . On e resul t o f thi s pivota l stud y wa s tha t som e specifi c emergenc y measure s wer e take n in

E " a l~~ l AUG . 197 4 ES 3 AUG . 197 6

1.5 T1. 8 

# JL M 1 2 3 4 5 6 7

B YAREA ISE E TEXT ! Figur e 7-4 . Annua l ambien t ai r lea d concentratio n nea r a smelter , b

y area , befor e th e Augus t 1974 an d Augus t 1975 sur veys. 2 4 Are a 1 I s withi n 1 mil e o fsmelter ; Are a 2 I s 1 t o 1-1/ 2 mile s fro m smelter ; Are a 3 , 2-1/ 2 t o 6 miles ; Are a 4 , 6 t o 1 5 miles ; an d Are a 5,1 5 t o 2 0 miles . 7- 8