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# 54 ) 11-1-7 1 Docket Number: 

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INVESTIGATION S INT O LEAD FRO M MOTO RVEHICLE S
A.C . Chattberlai n M.J . Hear d P . Littl e D . Newto n A.C . Well s R.D . Wiffe n

Repor t o f wor k a t AERE , Harwel l sponsore db y th e membe r companie s o f the Institut e o f Petroleum , Departmen t o f Energy , Departinen t o f th e Environment , Departmen t o f Healt hand Social Securit y an d Internationa l Lea dZin c Researc hOrganisation .

Environmenta l & Medica l Science s Division , AERE , HARWEL L
Novembe r 1S7 8 HL78/412 2 (C.10 )



### -I -P. 3

• • •

t . 2 .

3 .

-

4 .

5 . CONTENT S

Sunmar y Introductio

n 2. 1 2. 2 2. 3 2. 4 2. 5 Envi 3. 1 3. 2 3. 3 3. 4 3. 5

3. 6

3. 7 Origin s an

d object s o f th

e work Previou s publication s •

Reason s fo r environmenta l measurement s

20 3 Reason s for P

binhalatio

n an d injection experiment s Reason s fo

r ingestio

n experiment s ronmenta l measurement s Emissio n o f exhaus t lea

d fro m vehicle s Deposition of lea

d nea r road s Comparison o f rate s o f emission an d depositiono f lea d Th e possibl e us e o f shelte r belt s fo r Limitin

g dispersa l o f lea

d Concentration s o f lea d in ai r (a ) Roadsid e measurement s (b ) Measurement s i n car s (c ) Variation o f airborne lea d wit hdistanc e (d ) Urba n an

d suburban site s no t adjacen t t o (e ) Enclosed ca r park Particl e siz e analyse s (a ) Objective s an

d method s (b ) Motorway

aerosol s (c ) Urban , suburba n an d rura l area s (d ) Enclosed ca r park Chemica l compositio n of exhaus t lea

d Inhalatio

n o f stabl e lea

d 4. 1 4. 2 4. 3 Method s o f measuremen t Inhalatio

n experiment s i n th e fiel d Comparison o f fiel d an d laborator

y method s Inhalatio

n o f radioactive lea d aerosol s 5. 1 5. 2

5. 3 Objec t o f experiment s Preparation an

d inhalatio

n o f labelle

d aeroso ] (a ) Wind-tunne l aerosol s (b ) Bo xaerosol s Depositio

n o f labelled aerosol s i nth e lun g 5.3. 1 Wind-tunne l aerosol s 5.3. 2 Bo

xaerosol s 5.3. 3 Comparison wit hothe r publishe d wor k 5.3. 4 Variation between individual s

ISB N 0-70-580650- 2 -2 - fro

m mai n

s roa

d road s ".i . '-">"»FT» r » 1 ' » ' trai' T

Pag e No . 9 12 12 12 1 3 1 4 1 4 1 5 1 5 1 5 1 6 1 7 1 7 i e 1 9 1 9 2 0 2 1 2 1 2 1 2 2 2 3 2 5 2 5 4 1 4 1 4 2 4 3 5 0 5 0 V ; 5 1 5 2 5 2 5 2 5 3 5 4 5 4 I 1 T



### \

*-~ «

\

t

( • 'P. 4

CONTENT

S ICont'd ) « 6 . Clearanc e o f

labelle d aerosol s from th e lun g 6. 1 Objec to f

experiment s 6. 2 Method s o f

measurin g rat e o f

clearanc e 6. 3 Result s o f

lun g clearanc e experiment s 6. 4 Transfe rfrom lun g t o bloo d 6. 5 Dosag e o f

stabl e lea d 7 . Injectio n experiment s 7. 1 Objec t o f experiment s 7. 2

8 .

10 . 

### r. 3 Method s

20 3P bi n bloo

d followin

g injection 7.3. 1 Interchang e wit hextra-cellula r flui d

20 3 7.3. 2 Level s o f P bi n plasm

a 7.3. 3 Transfe r fro m bloo d t o site s o f storag e 203 „ 7.3. 4 P

bi n bloo

d fro m on e da v onward s 20 3 Excretio

n o f P

b 8. 1 Objec t o f measurement s 6. 2 Method s 8. 3 Excretio

n i n urin e 8. 4 Endogenou s feca l excretion 8. 5 Tota l excretion 8. 6 Excretion in relatio n t o 8. 7 Relation o f urinar y excretion t o
203 P b 20 3 P bi n blood 203 , P bin plasm

a Ingestio

n experiment s wit h 9. 1 Objec to f

experiment s 9. 2 Method s 9. 3 Uptak e fro

m th e gu t 20 3 9. 4 Observation s o n absorbed P

bfollowin

g ingestion 9.4. 1 203 P bi n bloo d 9.4. 2 Appearanc e o f systemi c lea d followin

g ingestio

n 9.4. 3 Excretion 9. 5 Summar

y o f result s o f ingestio nexperiment s Synthesi s o f AER E an d othe r result s 10. 1 Introductio n 10. 2 Uptak e an

d storag e o f

lea d i n Kehoe' s experiment s 10. 3 Uptak e and storag e o f lea d i n UCL

A experiment s 10. 4 Elevatio n o f

bloo d lea d i n experimenta l exposur e o f subject s t o Pb A (a ) Kehoe' s subject s (b ) Griffi n e taL' s subject s (c ) Tola' s subject s Pag. - Nc . 6 5 6 5 6 5 6 5 6 6 6 7 8 2 8 2 8 2 8 2 6 2 8 3 6 3 8 4 9 0 9 0 9 0 9 1 9 1 9 2 9 2 9 3 10 1 10 1 10 1 10 1 10 3 10 3 10 3 10 4 10 4 11 1 11 1 11 2 11 4
11 7 11 7 11 9 12 0
-3 --fT^"" " !--!: • f»* l IT" ' P. 5

CONTENT S (Cont'd )

10. 5 Survey s o f

bloo d lea d versu s ai rlea d i n variou s region s 10. 6 Bloo d lea d versu s wate rlea d 10. 7 Lead i n children' s bloo d 10. 8 Resorptio n o f

lea d from bon e (a ) Kehoe' s experiment s (b ) Bon

e lea d versu s ag e (c ) Bloo d lea d versu s ag e (d ) Bloo d lea d i n occupationa l versu s non-occupationa l group s (e ) Isotopi c ratio s i n lea d an d bloo d 20 4 (f ) UCL A experiment s wit h P b 10. 9 Possibl e schem e o f uptak e and excretio n o f lea d 10.1 0 Conclusion s Acknowledgement s Reference s

Tabl e 3. 1 Tabl e 3. 2
Tabl e 3. 3 Tabl e 3. 4 Tabl e 3. 5 Tabl e 3. 6 Tabl e 3. 7 Tabl e 4. 1 Tabl e 4. 2
Tabl e 4. 3
Tabl e 5. 1 Tabl e 5. 2 TABLE S Lea d depositio n rate s a tvariou s location s Measurement s o f

lead-in-ai rbesid e motorway s an d othe r street s Measurement s o f

airborn e lea d i n carborn e survey s Measurement s o f

airborn e lea d a tfixe d site s Particl e siz e analyse s Categorie s o f

particle s i n electro n micrograph s Volumetric-mea n particl e diameter s Depositio n i n lun g o f environmenta l lea d Depositio n i n lun g o f stabl e aggregate d exhaus tP b usin g fiel d equipmen t Percentag e depositio n b y radioactiv e and stabl e lea d analysi s 20 3 Particl e siz e o f

wind-tunne l 'Pl> v.xtaunt aerosol * Aggregate d aerosol s - Anderse n Impacto rdat a I ) 2 ) 203 ,

i 203 , i 203 „ Pb-labelle d exhaus taerosol s (1976-1977 ) Pb-labelle d lea d compounds (1976-1977 )
Tabl e 5. 3 Tabl e 5. 4 3 ) '""Pb-labelle d exhaus taerosol s (1975 ) (Well s e tal . 1977 )

Depositio n i n lun g o f wind-tunne l aerosol s Depositio n i n lun g o f aggregate d exhaus tan d othe r labelle d aerosol s 20 3 Pb

Pag e No .

12 0 12 1 12 3 12 3 12 3 12 4 12 4
12 4 12 4 12 5 12 5 12 7 14C 14G

.2 7
2 8 29 2 9 3 0 3 1 3 1 4 5
4 6
AT,

SC>

Tabl e 5. 5 Variatio n o f respirator y depositio n betwee n tw o subject s 5 7 5 8 5 6P. 6 "TT'-ITTTrTf"--'- "
CONTENT S (Cont'd )

•>0 3 Tabl e 6. 1 Lun

g clearanc e followin g inhalatio n o f 'Pb-labelle d aerosols . Compariso n o f exponentia l component s o rth e observe d mea

n clearanc e curve s fo rsi x differen taerosol *

20 3 Tabl e 7. 1 Possibl e distributio n o f P b afte rintravenou s salin e injectio n 20 3 Tabl e 7. 2 Mea n percentag e o f absorbe d P bappearing i n blood a t the pea k fo r variou s group s o f experiment s

20 3 Tabl e 7. 3 Pea

k level s o f P

bi n blood followin g intravenou s injection . Comparison o f subject s wit hmor e tha none attninistrat i o n Tabl e 7. 4 Biologica l half-live s o f P bi n bloo

d followin

g intravenou s saline injection compare d wit hothe r mode s o f intak e (individua l value s fo r salin e injectio

n experiments ) Tabl e 6. 1 Excretion o f P bfollowin

g intravenou s salin e injection - 197 7 serie s Tabl e 8. 2 Compariso n o f endogenou s feca l an d urinary

excretion i n differen t serie s o f experiment s *Wi** > Tabl e 8. 3 Accountin g fo rP b i n salin e injection s (197 7 series )

20 3 Tabl e 8. 4 Urinar y an d feca l excretio n o f P b relativ e t o concentration s i n *hol e bloo d followin g injectio n 20 3 Tabl e 8. 5 Compariso n o f th e observe d biologica l half-lif e o f P b i n Pagr No .

6 8

Tabl e 8. 6 Tabl e 9. 1 Tabl e 9. 2
Tabl e 9. 3 Tabl e 9. 4 Tabl e 9. 5
Tabl e 10. 1
Tabl e 10. 2
Tabl e 10. 3
Tabl e 10. 4 Tabl e 10. 5
Tabl e 10. 6 Tabl e 10. 7 Tabl e 10. 8 bloo d wit h th e calculatio n ( F + U) half-lif e fro m Tabl e 8. 4 20 3 Relatio n betwee n P b i n urin e and plasma , 0-4 6 hour s 20 3 Percentag e uptak e o f P b from th e gu t Percentag e uptak e o f lea d from th e gut : compariso n o f publishe d dat a 20 3 Th e hierarch y o f

subject s i n P

b injectio n experiment s 20 3 Percentag e uptak e i n gu to f Pb-labelle d exhaus taerosol s 3 0 *" r Half-lif e i n bloo d o f P b followin g ingestio n compare d wit h value s followin g salin e injectio n Storag e o f

lea d b y Kehoe' s subject s receivin g dail y ora l dose s Uptake , excretio n and storag e o f lea d i n Kehoe' • subject s M Rand E B Lea d balanc e i n Kelioe' s subjec tP C before , durin g and afte r exposur e t o airborn e lea d i n an experimenta l chambe r 20 4 Endogenou s feca l excretio n o f P b b y UCL

A subject s 20 4 Uptak e and storag e o f P b i n UCL

A subject s give n dail y ora l dose s 20 4 Estimate s o f half-lif e o f P bi nblood o f UCL

A subject s 20 4 P ban d tota l P

bi n die t an

d blood o f UCL

A subject s Respire d lea

d intak e b

y thre e method s (Mg/d ) 8 5
8 6

6 6
9 4
9 4 9 5

9 5
9 6 9 6 10 5

10 5 10 6 10 7

10 7

12 9

12 9

13 0 13 0
13 1 13 1 13 2 13 2

-5 -P. 7 •wpTT' T '"""fl f

""•""•"*' "

Tabl e Tabl e
Tabl e Tabl e
Tabl e Tabl e Tabl e
Tabl e Tabl e Tabl e 10. 9 10.1 0

10.1 1 10.1 2

10.1 3 10.1 4 10.1 5

10.1 6 10.1 7 10.1 6
Tabl e 10.1 9
Tabl e 10.2 0
Tabl e 10.2 1 CONTENT S ( Cont'd )

Sunmar y o f result s o f experimenta l exposur e t o lea d i n ai r Fi t o f exponentia l curve s to Pb B o f Dannemor a subject s in Fig . 10. 3 Mea n bloo

d lea d i n population s i nCaliforni a Predicted mea n childhood blood lea d (pg/iOO ml ) fo r variou s ai r an

d soi l lea

d concentration s nea r smelte r Elevation o f bloo

d lea d fro m ora l intake o f lea d Bloo d lea d an d dietar

y lea d Rati o o f intake s o f ai r an d foo d pe r uni t bloo

d volum

e fo r 1 0 yea r ol d childre n an d adult s Lea d in bloo

d o f children an

d mother s Lea d in tissue s a t pos t morte m (Barr y 1975 ) Schem e o f uptak e an

d excretio

n o f lea

d b y adul t mal e i n urba n distric t o f U K Relative contribution s to uptak e o f lea d i nanalysi s o f Ainswort he t al . (1977 ) Summar y o f estimate s o f elevationo f blood lea d o f adult s fro m exposur e t o ai r lea d Summar y o f estimate s o f rati o o f contribution s o f ai r lea d t o othe r lea

d intake s (adults ) Pag e No . 13 3
13 4 13 4
13 5
13 3 13 6

13 6 13 7 13 7

13 8

13 8

13 9

13 9
ILLUSTRATION S Fig . 3. 1 M 4 motorwa y a t Heston Fig . 3. 2 Concentration s o f P bi n ai r an

d rate s o f P

bdeposition t o gras s acros s th e M 4 motorwa

y Fig . 3. 3 M4 0 motorwa y Fig . 3. 4 Hogart hroundabou t Fig . 3. 5 Variation o f concentration wit hdistanc e fro m motorwa

y Fig . 3. 6 A

typica l motorwa

y exhaus t aeroso l viewed b y electron microscop

y a t thre e magnification s Fig . 3. 7 Vehicl e aerosols : siz e distribution o f thre e classe s o f

particl e Fig . 3. 8 Tota l particl e siz e distribution s a t M 4 (Hesto n an d Hogart h roundabout ) Fig . 3. 9 Level s o f airborn e P bina smal l tow

n Fig . 4. 1 Subject s inhaling exhaus t aeroso l o n th e hardshoulde r o f th e M 4 Fig . 4. 2 Carborn e inhalation equipmen t Fig . 4. 3 Deposition o f lea d inlun

g infiel d experiment s versu s lengt ho f respirator y cycl e 3 2

3 3 3 4 3 3 3 6

3 8

3 9 4 0

4 7 4 6

4 9>TWYT~' ' -«T^»' , " - -Tfr S P.8

Fig
. 5. 1 Fig
. 5. 2 Fig
. 5. 3 Fig
. 5. 4 Fig
. 5. 5 Fig
. 5. 6 Fig
. 6. 1 Fig
. 6. 2 Fig
. 6.3 a Fig
. 6.3 b Fig
. 6. 4 Fig
. 0. 3 Fig
. 6. G Fig
. 6. 7 Fig
. 6. 6 Fig
. 6. 9 Fig
. 6.1 0 Fig
. 6.1 1 Fig
. 6.1 2 Fig
. 7. 1 Fig
. 7. 2 Fig
. 7. 3 Fig
. 8. 1 CONTENT S (Cont'd )
Subjec t inhalin g aeroso l fro mwind-tunne l Wind-tunne l exhaus t aerosol s a s use di n inhalatio n experiment s Depositio n i n lun g o f wind-tunne l aerosol s 20 3

_ . , Depositio n i n lun g o f Pb-labelle daggregate daerosol s 1976-1977
. Percentag e depositio n versu s breathin g cycl e Depositio n i n lun g o f aggregate daerosols
. Compariso n o f mea n depositio n curve s A compariso n o f

publishe ddat ao n depositio n i n lun g o f submicro n particle s 203 „ Percentag e o f deposite d " P bremainin g i n lung , tunne l exhaus t aerosol s (0.0 2 Mm ) 203 p 7/7 / 2 0 3 „ Percentag e o f deposite d P bremainin g i n lung , expose d exhaus t aeroso l 7/7/7 6 Wind 

## u A

Clea n Percentag e o f deposite d "" ' P bremainin g i n lung , an d carbonaceou s exhaus t aerosol s

20 3 Percentag e o f P bremainin g i n lung . Carbonaceou s exhaus t aerosol s a t time s beyon d 1 0 hour s Percentag e o f deposite d nitrat e aerosol s Percentag e o f deposite d oxid e aerosol ? 203 , P bremainin g i n lung . Lea d
20 3 P bremainin g i n lun g

203 , Lea d
Compariso no f th e lun g clearanc e o f variou s aerosol s Pb-labelle d

Clearanc e o f variou s exhaus t aerosol s fro m th e lun g Compariso no f i n vitr o solubilitie s wit hlun g clearanc e

20 3 Level s o f P bi n bloo d followin g inhalatio no f exhaust , oxid e o r nitrat e aerosols , o r injectio no f PbCl , Lun g clearanc e a t differen t level s o f stabl e lea d depositio n Relationshi p betwee nstabl e lea d dosag e an d pea k level s i n bloo d fo r individua l subject s Normalise d relationshi p betwee nstabl e lea d dosag e an d pea k level s i n bloo d

20 3 Level s o f P bi n bloo d followin g intravenou s injection s o f 203 PbCl 2 i n salin e

203 , P bi n bloo d i n th e plasm a Percentag e o f 20 3 P bi n bloo d normali=e d t o 10 0 a t 6 0 hafte r intravenou s salin e injectio no f 203 PbCl , o f I T Rate s o f

trx'.rrrtio n o f

' P b i n urin e durin g th e firs t 3 4 hour s followin g intak r Pagr

- No
. 5< *
6 0 6 1
6 2
6 3

6 4
6 9
7 0
7 1
7 2

7 4
7 5 7 6

i I
7 8 7 9
8 0
8 1
8 7 8 8
8 9
!t 7P. 9

Fig . 8. 2

Fig . 8. 3

Fig . 8. 4

Fig . 9. 1 Fig . 9. 2 Fig . 9. 3 Fig . 10. 1 Fig . 10. 2 Fig . 10. 3

Fig . 10. 4 Fig . 10. 5 Fig . 10. 6 CONTENT S (Cont'd )

30"* L Rat e o f excretio no f P bi nurin e durin g th e firs t 3 6 hour s afte r inhalation . Compariso nof : (i ) 5 differen t aerosol s fo r on e subjec t (ii ) 4 differen t subject s fo r on e aeroso l

20 3 Excretio no f P bi n urin e an d fece s following : (a ) inhalation o f moto r exhaus t aerosols , an d (b ) I.V . injection o f 203 PbCl 2

20 3 Excretion o f P

bin urine expressed i n terms o f bloo

d plasm a 2° 3 Pb . Comparison o f intravenou s saline injection an d inhalation 20 3 Percentag e uptak e fro m the gut o f PbCl

_takenwit han d withou t accompanyin g foo d 20 3 Variation s o f leve l o f P bi n whol e bloo

d fo r variou s mode s o f intak e 20 3 P bi n leg s followin g ingestio

nan d inhalatio

n 20 4 P bi n bldo

d o f UCLA

subject s (Rabinowit z e t al . 1976b) . Curve s ar e fitte

d b y method (c ) o f Sectio n10. 3 20 4 Los s o f P

bfro m bloo d o f four subject s afte r withdrawa l o f isotope fro

m die t (Rabinowit z e t al . 1976b ) Bloo d lea d o f Dannemor a subject s exposed t o mea n 24-hour ai r concentration s o f 10. 4 pg/m 3 (above ) o r 3. 1 Pg/m 3 (below ) Increas e o f Pb

B i n Tol a e t aL' s subject s o n beginning wor k i n lea d industr

y Pb A an d Pb B i n Toky

o Lea d i n skeleton at death , normalised t o 7 0 k g bod y weigh t (Barr y 1975 ) Pag e No. .
9 8

9 9

10 0

io e
10 9 11 0

14 0

14 1

14 2

14 3 14 4

14 5P.1 0

I . Sui'nmar v I Thi' s repor t give s th- ; result s o f thre e years ' wor k o n lea d aerosol s in th

e environmen t an d th e laboratory . Th e >i ; :ak e o f bot hradioactiv e an d stabl e lea

d b y huma n volunteer s ha s been measured , wit hthe objec t of estimatin g th e uptak e b

y human s o f lea

d fro m petro l driven vehicles , an

d als o th

e contribution o f thi s t o th e tota l uptak e o f lead . Radioactiv e tracer s wer e use

d t o detenr.in

e th e effec t of chemica l composition o f lea d aerosol s o

n uptake , an

d als o t o comper e uptak e fru n lun & an d gut . Th

e effect s of lea

d o n healt hwer e no t included i n th e work . Earlie r wor k carried ou t in thi s projec t ha s beenpublished an d i s reviewed . Exhaus t 20 3 aeroso l labelle

d wit hP bwa s inhaled b y volunteer s an

d th e depositio n in the lun g an d uptak e b

y bloo d measure d b

y mean s o f the radioactiv e tracer . The result s wer e use d t o calculat e a vaiue fo r th e relation betweenbloo d lea d an d ai r lea

d expresse d a s

_Elevation o f bloo d lea d (ug/10 0 ml ) , a ~ Averag e 24-hou r exposur e t o ai r lea d (pg/m

) A calculatio n base

d o n 35% deposition o f th e inhale

d aeroso l i n th

e lung , 509

E transfe r o f th e lea d t o re d cell s an

d a 16-da

y biologica l half-lif e in blood , gav e a value of a o f abou t unitv . The wor k indicated th e significanc e of particl e siz e o n deposition i n th e lung . Ambient measurement s The particl e size , concentration an d dispersion o f ambien t lea d aerosol s wer e assesse d a t a variety

o f roadside site s t o determine th e typica l natur e o f airborn e lead . The result s indicat e tha t lea d emitted fro

m cruisin

g vehicles , a s o

n a motorway , i s mainl y a s very smal l discret e particle s of abou t 0.0 3 p m diameter . Unde r urba n drivin g conditions , wit ! vehicle s acceleratin g strongly , an

d whe n th

e aeroso l had'aged ' a s in ca r park s o r i n th e eountrxside . a wide r spectru m of particl e siz e wa s found , wit ! som e lea d attached t o agglomerat e particle s of 0.2- 2 (i n diameter . Contrar y t o report s fro

m th e USA , ver

y littl e lea d wa s associate d -.vit hparticle s greate r tha n5 pm . Correlatio n o

f measurement s b

y variou s author s shows tha t roadside concentration s are usuall y abou t 2 ug/ m

for each100 0 petrol-drive r vehicle s pe r hour , bu t ar e highe r o n gradient s an

d i n poorl y

ventilate d situations . Lea d concentration s decline rapidl y wit hdistanc e frc m a road . Th e mai n facto r i s i , upwar d dispersio n o f th e plum e rathe r tha

ndeposition o f th e lead ; onl y

abou t 10 £ o f th

e R | airborn e lea

d seeiis t o b

e deposite d withi n 10 0 m . \ ' Dispersio n calculation s relatin g traffi c flo

w t o th e concentratio n o f airborn e lea d a t variou s distance s fro m a roa d sugges t that , average d ove r 2 4 hours , fo r 100 0 V hthere i s a zone abou t 1 5 m

wid e o

n eithe r side o f th e roa d i n whic hth

e concentratio n exceed s I ..g/ m . Fo r a ver

y busy motorwa

y carryin

g 400 0 Vh ~ th

e equivalen t zone i s 10 0 m wide . Concentra tion s i n urba n house s ar e abou t 6<JZ o f thos e outside . Inhalatio n measurement s Volunteer s inhale

d fres han

d age d lea d aeroso l labelled wit hth e radioactiv

e isotope 20 3 Pb . Whe n fres haeroso l wa s diluted directl y fro m moto r exhaus t i

n a win d tunne l th

e stabl e lea

d concentration wa s about 40pg/ m . Fo r a respirator y cycl e o f 1 5 breaths/min . ther e wa s 4Q" " depositio n in th e lun g wit ha mea n particl e siz e o f 0.0 4 p m an d 70 S deposition

" 9 -P.1 1
wit h0.0 2 u

m particles . Depositio nwa s estimate dfro m th e concentratio ni n th e inhale dan d 20 3 exhale dair , an

d als o fro

m externa l gamma-ra y

counu : o f th e P bi n th e Aung . Alternatively , whe nth e exhaus t wa s allowe dt o aggregat e i n a boxfo r a n hou r o r two befor e inhalation , givin g highe r leadconcentration s sn d a particl e siz e abou t 0. 5 pm , thre e separat e serie s o f experiment s gav e 175? , 20* ? an d 23* ? fo r 1 5 breaths/mi nan d 1 litr e tida l volume . No t unexpectedly , depositio nalway s increase dwit ha slowe r breathin g cycle , though the increas e differe dbetwee nth e thre e series . Whe nvolunteer s inhale dth e ambien t leadaeroso l whil e seate dnea r a motorwa y o r travel lin g i n car s i n heav

y traffic , th e averag e depositio n(deduce dfro m th e lea dconcentration s i nth e inhale dand exhale dair ) wa s 6l £ nea r th e motorway , 64?t nea r a bus y roundabout , an

d 48r - alon« g urba nroads . Th e result s nea r the motorwa y wer e i n lin e wit hthos e fo r th e wind -

^ — - — . —— ~ . ___._———— ——• tunne l experiments . Thos e fro m the urba nroad s wer e highe r tha nexpecte dfro m th e laborator y wor k fo r reason s tha t wer e no t full y understood . Impactio no f large r particle s i n the urba n aeroso l i n th e Uppe r respirator y trac t ma y

hav e contribute dt o it s highe r deposition . Remova l fro

m th e lun

g 20 3 On e objec t o f th e inhalatio nexperiment s wit hP bwa s t o examin e whethe r the particl e size , chemica l compositio no r tota l mas s o f th e lead-bearin g aeroso l affecte dthe rat e o f remova l o f lea dfrom the lung t o th e bloo dstream . Onl y smal l difference s wer e foundwhe n fresh , age dan

d carbonaceou s exhaus t aeroso l wer e compared . Also , aerosol s o f lea doxid e an dlea dnitrat e wer e remove dfro m th e lun g a t a simila r rat e t o exhaus t aerosol . Th e uptak e wa s rapi da t first , the nslower , bu t i n al l experiment s (excep t on e 197 3 experimen t wit hL'.V . irradiate daerosol ) ove r 8G"* c o f th e lun

g burde nhad gon e b

y 2 4 hour s afte r inhalation . Th e fractio no f th e initia l lun g budre npresen t i n bloo d3 0 hour s afte r inhalatio nwa s remarkabl y constant . I t i s believe dtha t mos t o f th e lea dno t attache dt o re d cell s a t thi s tim e wa s elsewher e i n sof t tissues , o r i n bone . No t mor e tha na smal l percentag e o f th e initia l lead deposite di n th e lun g ha d bee nremove db y mucociliar y

actio nan

d swallowed . Difference s i n aqueou s solubilit y

a s betwee nleadoxid e an d nitrate , fres han

d carbonaceou s pyhanp t apmani a an dexhaus t aerosol s expose dt o sunligh t ma y hav e mad e some differenc e t o th e rat e o f clgar_ - anc e from

the lung , bu t no t enoug ht o affec t significantl y the relatio nbetwee nai r lea dan d bloo dlead Removal fro mblood , an dexcretio n 20 3 Sequentia l sample s o f venou s bloo dwer e take n up t o 1 4 day s afte r injectio n o f

Pb
. Radioactiv e deca y made i t impossibl e t o exten dth e measurement s further
. Ove r th e perio do f 20 3 measurement , th e P b disappeare dfro mbloo dexponentiall y wit h abiologica l half-lif e o f 16. 3

_ * 1. 1 day s (mea

n an dstandar derror)
. Afte r inhalatio n experiments , th e half-lif e wa s 16. 4 ^ 0. 7 days
. Th e 18-da y half-lif e agree s bettt r wit h th e result s o f UCL A worker s usin g " " 20 4 th e stabl e isotop e Pb
. 20 3 Urinar y an dfeca l excretio n o f P b wa s measure dfo r

1 4 day s afte r

intravenou s 20 3 injectio n o f

PbCl , i n salin e solution
. Thi s excretion , averagin g 0.83%o f th e dos e pe r 50*5 . da y i n urin e an d0.41 % pe r day i n feces , accounte dfo r th e reductio n i n th e P b i n th e subject' s body a s measure db y externa l ^amm ara y counting
. Thi s showe dtha t othe r route s o f excretio n (fo r

exampl e i n sweat ) wer e unimportant
. Th e rati o FA ' o f endogenou s feca l t o urinar y excretio n wa s 0.5
. Knowledg e o f thi s rati o assist s th e interpretatio n o f
1 0 -experi.»ent= . suc ha s thos e o f ke : ~ \ i nwinc hsubject s ar c give n ora l dose * of lead . Endo genou s reca l lea

d i s the

n masked reabsorbe d ora l lead , bu t if Ui e F^A1 rati o ran h e estimated , th

e uptake fro

m th e £ of

a n ora l dos e ca

n b e estimated fro

m th e uriiiur

v excretion . 20 3 Th e uptak e of P

bfro m th e ju t afte r ora l dose s wa s als o measured . Thc averag e uptak e o

f solubl e PbO , wa s 45 % whe n th e subjec t ha

d fasted overnight , but onl y Tl whe n he too k th e dos e wit ha meal . Wit hrelativel y insolubl e PbS , th e averag e uptake s wer e 12 ^ an d 6r"i . Ther e wa s considerabl e subjec t t o subjec t variation , which , i f i t applied t o uptak e o f stabl e lea

d i n roo d an d drin k woul d b

e enoug hi nitsel f t o explai n th e variation o f bloo d lea d i n norma l subjects . Relatio n betwee

n bloo d lea d an d ai r lea

d The previou s wor k suggested a valu e of unit \ fo r a , th e relatio

n between bloo

d lea d an d ai r lead . Althoug hth e difference s inresult s between th e presen t wor k an

d th e preview s ar e no t great , the

y indicat e a revisio n Tor th

e value o f a . The environmenta l lea d inhalation experiment s sugges t tha t 50 2 depositionshoul d b e assumed for th

e averag e urban dweller , an d 65 1 fo r th e smal l numbe r of peopl e continuousl y exposed t o motorwa y exhaus t lead . Als o th e percentag e transfe r fro m lun g t o bloo

d shoul d b

e increased slightl y t o 55% . A

biologica l half-lif e of 1 8 day s instea d o f 1 6 i s indicate d b y the result s o f th e injectio

n experiments . 20 4 an d thi s agree s bette r wit hwork a t UCL A usin g Pb . Th e ne t effec t o f thes e alteration s i s t o doubl e a fro

m 1 to 2 pg/10 0 m l pe r pg/ m . A furthe r smal l increas e migh t b e needed t o allo w fo r long-ter

m resorptiono f lea d fro m bone , whichcanno t b e demonstrated i

n th e time 20 3 scal e o f th

e P bexperiments . Othe r literatur e relevan t t o th e estimationo f a i s reviewe d at som

e length . The experi ment s of kehoe , i

n whic hsubject s inhale d lea d aerosol s a t concentration s rangin g fro m 1 0 t o 5 15 0 ug/ m

fo r a numbe r o f hour s pe r da y fo r man y months , yiel d a

n averag e value o f a -- • 1.2ug/10 0 g pe r ug/ m

. Ther e i s som

e evidenc e tha t a decrease s wit hincreasin g lead-in-ai r concentrations , probabl y

o n accoun t of mor e rapi d excretio n o f lea

d fro m th e blood . Th e mor e recen t exposur e o f voluntee r subject s t o lea d in ai r (10. 4 an

d 3. 1 Pg/m 0 ) a t Dannemora , N.Y. , gav e a . = 1. 5 an

d 1.7 . Som e recent epidemiologica l survey s relatin g bloo d lea d wit hai r lea

d are als o reviewed . Contribution o f airborne lea d to tota l uptak e The fina l sectio

n o f th

e repor t reviews thi s an d othe r wor k t o evaluat e th e relativ

e contribution o f lea d i n ai r t o th

e tota l uptake . Th e difficult y

i s t o estimat e th e uptak e o f dietar y lea d fro m th e gut . I f Kehoe' s lea d balanc e experiment s are re-analysed wit htli e assumption tha t th e rati o F A ' o f endoienou ; 20 3 e feca l to urinar

y lea d wa s 0. 5 (a s foun d i nth e Harwel l P

bexperiments) , th e fractiona l uptak e fro

m gut i s foun

d t o averag e 0.15 . A possibl e schem

e o f uptak e an

d excretion can the n b e constructed , i n whic hth e uptak e o f lea

d fro m th e lun g in a person exposed t o I Pg/ m da y i n ai r i s 7. 5 pg/day , compared wit h4 1 pg/day uptak e fro

m th e gut . Thi s approachindicate s tha t th e contributiono f ai r lea d t o tota l uptak e a t thi s leve l o f exposur e i s about 16% . A t th e highes t level s t o whichpeopl e ar e continuousl y exposed (fo

r exampl e in house s adjacen t t o th e busies t stretc hof th e M4) , th

e contribution o f ai r lea

d t o tota l uptak e woul d appea r t o b e comparabl e wit htha t fro m diet . However . fo r th e majorit y

o f urban an

d rura l residents , fo r who m airborne lea

d average s les s tha n

- 5 o. a Pg/ m

, thi s wor k indicate s tha t th e contribution o f ai r lea d t o tota l uptak e i s les s than 10"*" .

- I I -P.1 3

2 . Introductio n 2. 1 Ori . s an

dobject s o f th

e wor k Th e projec t starte di n197 4 wit hth e objective s o f determinin g the depositio ni n th e huma nlun

g o f leadfro

m moto r exhaust , th e uptak e t o blood , and , a s fa r a s possible , th e subsequen t fat e o f th e absorbe dlead . A repor t o nth e firs t stag e o f the wor k wa s submitte di n197 5 (subsequentl y substantiall y

published) . I n197 6 a continuatio no f th e projec t wa s undertake nwit hth e objective s (a ) t o stud

y th e effect s o f chemica l change , particl e siz e an ddifferen t mode s o f engin e operatio no nth e retentio nan drat e o f uptak e i nth e lun g o f exhaus t leadaerosols , a t concentration s whic har e realisti c i nrelatio nt o ambien t levels , (b ) t o establis hmor e firml y th e rati o betwee nth e amoun t o f absorbe dleadwhic hi s eventuall y

excrete dwit hth e fece s andtha t excrete dwit hth e urine , (c ) t o defin e the relativ e contribution s o f inhale dan dingeste dleadt o overal l leadabsorption , (d ) t o attemp t t o determin e th e distributio nandfina l locatio no f absorbe dleadno t accounte dfo r i nth e bloo do r b y excretion , (e ) t o evaluat e othe r publishe dstudie s o nth e uptake , distributio nwithi nth e body , retentio nandexcretio no f leadan dt o relat e thei r finding s t o th e presen t study . 20 3 Th e origina l conceptio nwa s t o us e a radioactiv e trace r ( Pb ) t o labe l th e lead i npetro l andthu s enabl e the depositio ni nth e lung an dsubsequen t fat e o f th e exhaus t lea dt o b e followed . Th e labellin g allow s th e lea dinhale ddurin g a specific , shor t ter m experimen t t o be distinguishe dfro m the leadi nth e bod y originatin g fro

m othe r sources . I t wa s foun dtha t th e particl e siz e o f th e lead , whic hdepend s o nth e condition s o f generatio nandstorag e o f th e aerosol , markedl y affect s th e depositio n i nth e lung , a s woul db e expecte dfro m othe r wor k oninhalatio no f particles . I t becam e eviden t tha t th e publishe dinformatio no nparticl e size s o f lea di nth e environmen t wa s inadequate , anda samplin g programe wa s begu nt o obtai nmor e informa tion , wit hparticula r referenc e t o possibl e difference s i nparticl e siz e unde r differen t environmenta l conditions . Th e concentration s o f leadi nair , nea r th e M 4 motorwa y

andnea r othe r heavil y use durba nroad s wer e foun dt o b e hig

henoug ht o enabl e the depositio ni nth e lun g o f th e ambien t lea daeroco ) t o b e nvaaurM h y «•««: . parin g lea dconcentration s i ninhale dan dexlwilr

d«lr . Thl ? wa s see na * a tiprfti l chec k o nth e conclusion s o f the wor k wit hradioactiv e aerosols . A s i t turne dout , considerabl e effor t wa s require dt o correlat e th e result s o f th e laborator y (radio activ e lead ) andenvironmenta l (stabl e lead ) measurements , an dintegratio no f th e result s int o a coheren t pictur e ha s prove ddifficult . 2. 2 Previou s publication s Th e result s o f the firs t phas e o f th e projec t wer e publishe d(Chamberlain , e t al . 1975) . Th e abstrac t o f the pape r wa s a s follow s

-12 -P.1 4
"Tetraethy l leadwa s labelle dvtith Pb , adde dt o petrol , andburn t i na nengine . Th e exhaus t aeroso l -va s inhale d b

y volunteer* , usuall y afte r i t hadbee nstore di na box , but i na fe

w experiment s directly , a few metre s downwin do f th e engine . Th e percentag e depositio ni nth e lung , uptak e t o bloo dan dexcretio no f th e labelle dleadwer e measured . Th e percentag e depositio ni nthe lung depende donth e lengt ho f the respirator y

cycl e -MB S 3 5 i 2 (s.e.)% . half-lif e o f abou t 6 h . Abou t hal f o f the amoun t deposite di nthe lun g Fo r a 4 s cycl e (1 5 breaths/min ) th e depositio n

20 3 Mos t o f th e P bwa s ronove d fro m th e lung wit ha

wa s i nth e bloo da t 5 0 hafte r inhalation . A simila r fractio nwa s i n 20 3 th e blooda t th e sam e tim e afte r injectio no f PbCl

_i nsalin e solution . 20 3 From thi s andothe r evidenc e i t i s deduce dtha t mos t o f th e P bpasse d fro m the lung t o th e bloodplasma . Abou t hal f wa s remove dt o bon e and othe r tissues , an dhal f becam e attache dt o re dcells . Fro m abou t 7 2 h 20 3 onwards , th

e amoun t o f Pbi nbloo ddecline dwit ha mea nbiologica l half-lif e o f 1 6 d . Assumin g tha t th e same half-lif e applie s beyon d th e perio dfo r whic hmeasurement s wer e made , th e result s ca nbe use dt o predict tha t continuou s (2 4 h/d ) exposur e t o 1 ug/ m o f exhaus t lea d ove r a perio do f month s wil l giv e a naverag e contributio no f abou t 1 ug/10 0 m l t o bloo dlead . Result s o f othe r wor k onexperimenta l an d industria l exposur e o f person s t o lea di nai r appea r consisten t wit h this. " A shorte r pape r coverin g muc hthe sam e groundwa s publishe di nth e Postgraduate Medica l Journa l (S±, 790-4) . A pape r (Wells , e t al . 1977 ) wa s give na t th e Edinburg hConferenc e o nInhale d Particle s i nSeptembe r 1975 . Thi s wa s mainl y concerne dwit hth e effect s o ndeposi tio ni nth e lung o f varyin g th e respiratory parameter s (lengt ho r breathin g cycl e an d tida l volume) . Th e lengt ho f th e respirator y cycl e wa s foun

dt o b e a majo r facto r i ndeterminin g the depositio no f th e sub-micro nexhaus t aerosol , fo r whic hBrownia n diffusio ni s th e chie f mechanis m o r transfe r t o th e lung surface . Whe nth e deposi tio no f 'win

d tunnel ' and'box ' aerosol s wa s compared , i t wa s foun dtha t th e wind tunne l aeroso l gav e highe r depositio n(40 % compare d wit h14* % a t 1 5 breaths/min) . Th e win dtunne l aeroso l wa s prepare db y dilutin g the exhaus t rapidl y wit hclea nair , thu s givin g a smalle r particl e siz e tha nth e aggregate daeroso l obtaine db y storag e i nth e box . I t wa s pointe dou t b y Well s e t al . tha t th e rang e o f variatio ni nth e percent ag e lun g deposition , onvariou s assumptions , woul dcorrespon dt o a four-fol dvariatio n i nth e calculate drelatio nbetwee nbloo dlea dan dai r lead . 2. 3 Reason s fo r environmenta l measurement s I t wa s know

nfro m earlie r wor k (Lawthe r e t al . 1973 ) tha t the primary lead-bearin g particle s emitte dfro m cruisin g engine s wer e ver y smal l ( < 0. 1 p

m diameter) , bu t coagu late dwit hothe r aerosol s i nth e urba natmosphere . Also , Anerica nreport s hav e state d tha t large r particles , I nth e 1-1 0 p m siz e range , ar e emitte dI ncertai ncon d 11. 1 on * suc ha s rapi dacceleratio nan dascen t o f hills . I t wa s therefor e decide dt o mak e measurement s o f lea di nai r (PbA ) an dparticl e siz e spectr a I nsi xtype s o f location *

-IS -P.1 5 (a ) alongsid e amotorwa y i n leve l countr y (b ) alongsid e amotorwa y on astee p gradien t (c ) i n and nea rmajo rurba n highway s (d ) i n urba n area s no tclos e t o majo rroad s (e ) i n a

n urba n multi-store y ca rpark (r ) i n arura l area . Th e opportunit y was take n t o measur e lun g depositio n i n volunteer s inhalin g th e ambien taerosol . Thi s was don e i n location s (a) , (c ) and (e ) above , wher e th e Pb A level s wer e hig h enoug h t o enabl e thi s t o b e done .

20 3 2. 4 Reason s ro

r P binhalatio

n an d injectio

n experiment s Th e earlie r wor k ha

d demonstrated th

e dirrerenc e in lun g deposition betwee n th e win d tunne l an

d bo xaerosols . I n 197 7 a mor e thoroug hstud y o r th e errec t or particl e siz e i n the rang e 0.0 2 t o 0.0 9 u m wa s made . The variation wa s achieve d b y varyin g th e rapidity

or dilutio

n o r th e exhaust . Thi s stud y o r the errec t o r physi ca l ror m wa s in paralle l wit ha stud y o r the eject s o f chemica l stat e o f the lead . I n th e earlie r wor k irradiation or th e exhaus t aeroso l in sunligh t ha d appeare d t o afree t th

e rat e o

r clearanc e rro

m th e lung . I t wa s considere d desirabl e t o exten d thi s work . Th e chemica l ror m o r exhaus t lea

d i s ver

y variable . I n th e wor k or Keho e (1961b , 1966 ) an d Grirri n et al . (1975 ) volunteer s wer e exposed t o airborn e lea d generated b

y burnin g T.E.L . in propane , givin g oxide particles . I t wa s there fore desirabl e t

o tes t whethe r chemica l rorm s materiall y

altered th

e uptak e o r lea

d particle s rro

m th e lung . Anothe r serie s or experiment s wa s don e t o measur e the uptak e b y blood , an

d excre 20 3 tion i n urin e an

d rece s o r P

bgive n b

y intravenou s injection . Ther e wer e tw o mai n objectives . Firstly , th e measurement s o r externa l gamm a radiation followin g injec tion , togethe r wit hsimila r measurement s followin g inhalation , enabled th e transfe r o r 20 3 20 3 P brro m lun g t o bloo d t o b e assessed . Secondly , measurement s or P bi n excret a followin

g injection gav

e urinar

y an d feca l excretion rates . Th e rati o F A l o f endo genou s feca l t o urinar y excretion i s a usefu l paramete r t o appl y t o measurement s o f excretion o r stabl e lead . Becaus e o r th e presenc e o r unabsorbe d dietar y lead i n feces , i t i s dirficul t t o asses s th e contribution o f endogenou s feca l lea d excep t b

y trace r studies . A knowledg e o f th

e F_A ! rati o i s needed t o asses s the uptak e o f dietar y lea d fro m th e gu t b y strikin

g a balanc e between uptak e an d excretion . 2. 5 Reason s fo

r ingestion experiment s The reaso

n fo r wanting t o kno

w the percentag e uptak e fro m gu t i s t o enabl e som e assessmen t t o b e mad e o f th e relativ

e contribution s o r airborn e an d dietar

y lead . As a contribution t o this , a stud y wa s mad e o r the uptak e b y volunteer s wh o too k ora l 20 3 close s or P

bin solubl e (PbCl 2 ) an d insolubl e (PbS ) states . Eac hsubjec t too

k eac htype o r dos e aTte r Tastin g overnigh t an

d agai n wit ha standar d meal , t o establis h i f th e uptak e o f a trace r dos e o f lea d i s influenced b

y th e presenc e o f foo

d in th

e gut .

-14 -3 : Environmenta l measurement s i Th e objective s o r the measurement s wer e a s follow s (a ) t o determin e the physica l characteristic s o f th r leadaerosol , (b ) t o measur e the fractio no f exhaus t lea ddeposite dnea r t o it s source ; thi s fractio ni s no t availabl e f6 r inhalatio n(unles s resuspende db y some nechanism ) bu t ma y contribut e t o ingeste dlead , (c ) t o measur e the percentag e depositio no f environmenta l leadi nthe lung s o r volunteers . ' Th e monitorin g o r airborn e leadlevel s wa s no t a nobjectiv e i nitself , bu t sufficien t dat a wer e collecte di nth e cours e o f thi s wor k t o b e wort hreportin g andcomparin g wit h othe r publishe dwork . 3. I Emissio no r exhaus t leadfro m vehicle s Th e tetr a alky l leadriui dadde dt o petro l i s burn t i nth e engin e andmos t o r i t i s exhauste da s a Tin e particulat e aerosol . Th e quantit y o r lea dconsume db

y th e engin e depend s upo nit s concentratio no r Pbi npetrol , an dth e rat e o r petro l consump tio nwhic hi ntur ndepend s o nthe size , efficiency , running spee dandloa do f th e engine . Th e proportio no f exhauste dlea dwhic hi s emitte dt o th e atmospher e depend s no t onl y

upo nth e age , temperatur e an dphysica l stat e o r the exhaus t system , bu t als o upo nthe manne r i nwhic hth e engin e i s operated , andma y vary fro m 20 % t o 300% . Fo r example , unde r condition s o r heav y acceleration , lea ddeposit s whic hhav e accumulate d i nthe exhaus t syste

m unde r idlin g o r stead y cruisin g condition s ma y b e resuspende d andemitte dfro

m th e tai l pipe . Afte r reviewin g America nliterature , Huntzicke r e t a L (1975 ) too k fo r purpose s o f calculatio n75 % emissio no r lead . Assortin g a petro l consumptio no f 3 0 mpg , 75 % emission , anda mea nconcentratio no f P bi npetro l o f 0.4 9 g 1 , th e emissio no f P b i s 5 6 m g pe r mile . Measurement s a t Warre nSprin g Laborator y o f emission s fro

m a 110 0 c c ca r gav e 4 6 mg/mil e a t 5 0 mph , 6 1 mg/mil e a t 6 0 mp hand8 2 mg/mil e a t 7 0 mp h (Hogbi nan

dBevan , 1976) . Th e increas e wit hspee di s du e partl y t o increase dfue l consumptio nandpartl y t o increase dpercentag e emissio na t highspeeds . I f 100 0 cars/h r pas s alon g a road , an deac hemit s 6 1 mg/mile , the nth e tota l emissio ni s 16. 9 ings " pe r mil e o f roa do r 1 0 u g m ~ s ~ . Thi s figur e ha s bee n adopte db

y Chamberlain , e t al . (1978 ) i ncalculation s o f th e theoretica l concentratio n o f lea di nai r downwindo r a road . Littl e an dWirre n(1978 ) i nwor k o ndepositio n nea r the M 4 motorway , adopte dth e slightl y lowe r figur e o r 7. 7 u g » " s ~ , correspond in g t o 60 % emissio nwit hth e othe r factor s a s above . 3. 2 Depositio no f leadnea r road s Th e subsequen t fat e o f P bemitte dt o th e atmospher e determine s the route s o f P b uptak e b

y man . I t i s importan t t o kno w ho w muc hP bemitte dby

car s i s deposite di n th e nea r vicinit y

o f a bus y

roa dandho

w muc hremain s airborn e an dma y b e Inhaled . Fo r thi s study , a sectio no f th e M 4 motorwa y wa s chose nbetwee nJunction s 2 an d3 a t Heston , London , wher e i t carrie s abou t 90,00 0 vehicle s pe r da y (Fig . 3.1) . T o th e

-IS -P.1 7

north , Va lan d i s permanen tpastur e and t o th e sout h roug h grassland . I T depositio n o rpart i - s i s measure d wit h deposi tgauge s ther e remains th e proble m o rrelatin g th e catc h i n th e gaug e t o tru e depositio n t o th e plan tan d soi l surraces . Littl e and 20 3 Wirre n (1977 ) hav e measure d depositio n o rPb-labelle d exhaus tt o plan tan d soi l surrace s i n awin d tunnel . Th e depositio n velocit y define d b y



### g 20 3 2

P bdeposite dpe r c m

o f groun dsurfac e pe r se c Concentratio no f P bpe r c m o r ai r
wa s 4 time s greate r t o shor t gras s an d underlyin g soi l tha nt o bar e soi l b y itseir . Thi s wa s becaus e leave s ar e erricien t i n capturin g smal l particles . Consequentl y direc t measurement s o r th e P bconten t o r tray s o r gras s beror e an d arte r a perio do r exposur e besid e th e motorwa y wer e mad e (Littl e an dWirren , 1978) . Th e result s o r on e experimen t ar e show ni n Fig . 3.2 . Th e rate s o T depositio n varie dconsiderabl y o n dirreren t days , largel y becaus e th e win dspee dvaried . Th e result s o r Littl e an dWirre nar e compare di n Tabl e 3. 1 wit hothe r measurement s o r depositio no r P bnea r road s an d als o nea r smelters . Th e depositio nbesid e th e M 4 i s consisten t wit hothe r dat a reporte dro r roadsid e sites . Compariso nwit hsmelte r site s show s tha t althoug hP bdepositio nrate s ar e heav y besid e th e M 4 a s i n th e vicinit y o r smelters , th e zon e arfecte db y heav y depositio nfro m

th e M 4 i s narrow . onl y extendin g t o abou t 30-5 0 m rro m th e motorway . Robert s e t al . (1974 )

- 2 - 1 -2- 1 considere dtha t depositio nrate s o r mor e tha n10 0 m g m mont h(3. 3 m g m d ) wer e excessiv e To r residentia l areas , a criterio nadopte dby th e Canadia nBoar do r Healt han dMinistry ' o r Environment . I n th e presen t study , thi s leve l wa s no t exceede d beyon d1 5 m

rro m th e motorway , eve ndurin g period s whe nth e win dwa s blowin g i n tha t directio nrro m

th e motorway . 3. 3 Compariso no r rate s o r emissio nan ddepositio no T lea d Littl e an d Wirre n(1978 ) calculate dth e proportio no r th e lea demitte drro m vehicle s o n a motorwa y whic hi s deposite dwithi n10 0 m , usin g th e result s describe d i nth e previou s paragraph . Th e result s indicate dtha t onl y abou t 10 % o T P bemitte d unde r stead y

cruis e condition s o n a leve l motorwa y i s deposite dwithi n10 0 m o r th e motorway , abou t 90 % renainin g airborn e ro r lon g rang e dispersal . ThereTor e th e declin e i n concentratio no r lea di n ai r wit hdistanc e fro m th e motorwa y

illustrate di n Fig . 3. 2 i s du e onl y i n smal l degre e t o deposition . Th e mai nfacto r i s upwar ddis persio no f th e plume . Huntzicke r e t al . (1975 ) usin g averag e P bemissio ndat a fo r Lo s Angeles , calculate dtha t onl y abou t 6 % o f th e calculate demissio nwa s deposite d withi n15 0 m

o r a bus y

freeway . Th e possibilit y o f direc t depositio no r larg e particle s t o th e motorwa y surfac e ha s bee nconsidere d(Littl e an dWirren , 1977) , bu t particl e siz e analysi s showe dtha t eve nwithi n1. 5 m o f th e trarfi c les s tha n10 % o r th e mas s o r lea dwa s associate dwit hparticle s o r 5 pm o r greater . A t motorwa y acces s points , roundabout s an d trarri c light s wher e especiall y heav y acceleratio n occurs , ther e ma y

b e a highe r percentag e o r large r particle s (Habibi , 1973 ; Huntzicke r e t al . 1975 ) an d th e percentag e depositio nclos e t o th e roa dma y b e greater . A s a n alternativ e approac ht o thi s question , Littl e an dWifTo n(1978 ) measure d

• 16 -P.1 8

th e tota l P bconten t o f soil s andvegetatio ni ntransect s ou t t o 10 0 m fro m th e Motorway , andcompare dth e tota l depc.-' t wit hth e calculate dtota l P bemissio nsinc e th e openin g o f th e motorwa y i n1965 . Th e concentration s i nvegetatio nan dsoil s a t 10 0 m wer e take na s representin g th e genera l backgroun dlevel s o f urba ncontaminatio n andwer e subtracte drro m th e concentration s measure dclose r to th e motorwa y t o arriv e a t the exces s attributabl e t o th e tota l emission . Th e result s Indicate dtha t abou t 4 0 % o r th e P

bemitte dove r the pas t 11 year s ha s bee ndeposite dwithi n10 0 m , compare d wit hthe figur e o f 10 % derive dfro m measurin g th e curren t deposition . Th e reaso nfo r thi s difTerenc e i s no t know nfo r certain . I t i s possibl e tha t depositio ni s greate r durin g rainfall , bu t rai nfall s fo r onl y abou t 10 % o f the time , an deve nwit hth e unlikel y assumptio ntha t durin g rai nal l th e lea dwa s deposite d withi n10 0 m , tha t woul dincreas e th e time-average ddepositio nonl y fro m 1 0 t o 20% . Anothe r mor e likel y

reaso nfo r th e discrepanc y i s th e re-suspensio no f lea dfro m th e roa dsurfac e especiall y whe ni t i s wet . Thi s ma y includ e lea di noi l whic hha s falle nonthe roa da s wel l a s exhaus t lea d(Littl e an dWiffen , 1978) . I ndry conditions , ther e appear s t o b e littl e re-suspensio no f lea dfro m road s wit hth e norma l surface , sinc e electro nmicroscop e studie s an dparticl e siz e analysi s hav e faile dt o demonstrat e associatio no f lea dwit hre-suspende ddust . 3. 4 Th e possibl e us e o f shelte r belt s fo r limitin g dispersa l o f lead Th e possibl e us e o f hedge s o r belt s o f tree s fo r increasin g particl e depositio n clos e t o emissio nsource s an dfo r limitin g th e dispersio no f pollutio nha s attracte d attention . Th e studie s o f Impen s e t al . (1972) , Kelle r (1974) , an dHeiche l an

d Hanki n(1976 ) hav e al l demonstrate dtha t interceptio no f exhaus t P bby hedge s o r tree s ma y b e ver y

efficien t an

dtha t P bdepositio nclos e t o a motorwa y ca nb e greatl y increase db

y plantin g trees . Heiche l an dHanki n(1976 ) fo r exampl e demonstrate dtha t accumulatio no f Pbi nsoi l unde r a roadside ' coniferou s windbrea k wa s twic e tha t o f ope ngroundoutsid e th e windbreak . Althoug hth e presenc e o r tree s ma y increas e th e rat e o f Pbdepositio nclos e t o a motorway , th e actua l quantit y deposite dma y

b e quit e smal l i nrelatio nt o th e emissio n source . Fo r example , th e long andshort-ter m depositio nrate s t o gras s andsoi l betwee n5 an

d3 0 m o f th e M 4 wer e onl y 4. 5 an d2.0 % respectivel y

o f th e tota l P b emitted . Eve ni f thes e depositio nrate s wer e double db y th e plantin g o f a bel t o f tree s betwee n5 and3 0 m fro m th e motorwa y

a s observe db

y Heiche l an dHanki n(1976) , th e increase ddepositio nwoul dstil l represen t les s tha n10 % o f tha t emitted . 3. 5 Concentration s o f lea di nai r Th e concentratio no f airborn e lea ddepend s o nth e distanc e fro m the roadway , traffi c density , drivin g mod e an dpetro l consumption , win dspee danddirection , surroundin g topography , an do nthe atmospheri c stabilit y whic hdetennine s th e upwar d dispersio no r near-groun dsource s o r pollution . Measurement s o f airborn e lea dwer e mad e i nth e cours e o f th e investigation s o f depositio nnea r the M 4 motorwa y (Littl e andWirren , 1978 ) andals o a s par t o f a study o f th e retentio no f airborn e leadI nth c lung , describe dbelow . I naddition , some measurement s wer e mad e o f th e urba nan d rura l backgroun dconcentrations .
-17 -P.1 9

Th e airborn e P

b concen tra tion s wer e monitore d wit h ai rfilte rsample s (Whatma n CF/A) normall y a taheigh to f 0. 3 m abov e ground . Tti e lea d wa

s measure d b

y atonii< : absorptio n spectrophotometr y (AAS) . Th e filte rbackgroun d was 0. 2 Mg , s o tha twit h one-hou rsamplin g a t1 0 l/min , aminimu m lea d concentratio n o f 1. 3 p g m

~ coul d b e measured , an d wit h 24-hou rsampling , th e limi twas 0.0 6 p g m . A n attemp twa

s mad e t o relat e thes e measurement s and other s reporte d i n th e literature , t o th e trarfi c flow s wher e thes e wer e known . (a ) Roadsid e measurement s Measurement s hav e bee n reporte d b y Littl e an

d WifTen (1978 ) fro

m aleve l Stretc h o rth e M

4 a tHeston , Middlese x (Fig . 3.1 ) and from astretc h o f th e M4 0 wher e i tascend s th e Chilter n escarpmen tpartl y o n embankmen

tand partl y i n cutting , wit h an averag e gradien to r1 i n 2 5 ove radistanc e o r2. 5 k m (Fig . 3.3) . Th e resul to ron e experimen ti s show n i n Fig . 3.2 , and th e mea n results , norma lise d t o atrarri c flo w o f 100 0 cars/hr , ar e summarise d i n Tabl e 3.2 . O n th e M 4 th e upwin d cemcentratio n wa s abou t0. 4 ug/

m , whic h i s atypica l backgroun d leve l fo rth e area . Thi s ha s bee n subtracte d fro m measurement s o n th e downwin d hard shoulde ri n calculatin g th e normalise d concentration s pe r100 0 petro l drive n vehicle s pe rhour . Earlie rmeasurement s b y Beva n e tal . (1974 ) o f

concentration s i n th e centra l reservatio n o rth e M 4 a tHesto n ar e als o summarise d i n Tabl e 3.1 . Th e theoretica l resul tX = 3 » 3 M g m ~ pe rlOO

O Vh ~ wa s calculate d b y Chamberlai n e tal . (1976 ) usin g Pasquill' s (1974 ) theor y o rdirfusio n o rsmok e fro m lin e sources . Averag e meteorologica l condition s wit h win d spee d 2 m s ~ a t1 m abov e groun d wer e assumed . Theor y indicate s tha tth e inclinatio n o f th e win d t o th e motorway doe s no tgreatl y affec tth e resul tunles s i ti s nearl y paralle l t o th e road , i n whic h cas e x i s increased . Fo rcompariso n wit h lon g ter m measurement s besid e roads , areductio n by afacto ro f 1. 5 t o 2 woul d b e neede d t o allo w fo r wind s blowin g bot h way s acros s th e road . The value s o f

x besid e th e heavil y grade d M4 0 ar e highe rtha n thos e besid e th e M4 , mainl y becaus e mor e fue l i s use d on th e gradient . Wher e th e M4

0 run s i n acutting , poo rdispersio n increase s th e concentratio n further . Compara tivel y hig h concentration s o f lea d (averagin g 5. 3 p g m * ) had previousl y bee n observe d b y Lawthe re tal . (1973 ) adjacen tt o agrade d stree ti n Hampstead . Th e trafri c flo w i s no tgive n b y th e authors , bu tvehicl e count s i n th e stree ti n Hampstead i n 197 2 (kindl y mad e availabl e b y Mr . P.W. Munt ) indicat e tha tth e . 24-hou raverag e flo w was abou t120 0 vehicles/hr , wit h aver y hig h proportio n o r petro l drive n vehicles . Assumin g aloca l backgroun d o r0. 4 M g m ~ , x equal s 4. 1 u g m

~ pe rlOO

O Vh " a tthi s location . Als o show n i n Tabl e 3. 2 ar e measure ment s b y Harriso n e tal . (1974 ) o rairborn e lea d and trarri c flo w i n London streets . Talgart h Roa d i s th e lin k betwee n th e Haiimersmit h flyove ran d Cromwel l Roa d an d th e trafri c flo w an d P b concentratio n compare wit h thos e on th e M4. I n th e presen twork , measurement s wer e mad e a tth e Hogarth roundabou ti n Chiswic k (A4/A316 ) wher e th e trarri c from th e M 4 enter s urba n Londo n (Fig . 3.4) . Tlie mea n concentratio n i n daytim e sample s on e metr e fro m tli e ker b wa

s l< ) tm m .

-18 -P.2 0

Th e traffi c flo w betwee n lOO O an d 150 0 hour s was betwee n 450 0 an d 550 0 ,-s/hr . I n anearb y stree tabou tJ O m downwin

d o f th e roundabout , concentration . cragln g

- 3 - 3 4 ug m wer e found . Th e daytim e concentration s o f 3 t o 4 u g m rot : \ v Harriso n e tal . I n Wes tEn d street s ma

y b e compared wit h daytim e mets u . . ;ent * o r 6. 4 u g m

" i n Flee tStreet , 2. 3 u g m " I n Clerkenwel l Roa d an d I. S p g a " a t St.Bartholomew' s Hospita l by Lawthe re tal . (1973 ) Lawthe re tal . giv e mea n daytim e and mea

n 24-hou rlevel s i n London , an d th e Departmen to rth e Environmen t(1976 ) giv e mea n daytim e an d nighttim e level s i n Birmingham . Beva n e tal . (1974 ) giv e th e diurna l variatio n o rconcentratio n o n th e M4 . Wher

e concentration s ar e relate d t o loca l trarri c density , th e 24-hou rmea

n ca n b e expecte d t o b e afacto r1. 2 t o 1. 5 lowe rtha n th e daytim e mean . Wher

e advectio n fro

m adistanc e contribute s ahig h proportio n o f th e concentration , ther e i s ofte n littl e differenc e betwee n day and nighttim e values . A tth e botto m o f

Tabl e 3.2 , th e result s o f tw o statistica l correlation s o f urba n kerbsid e lea d concentration s an d traffi c flo w ar e given . Thes e relat e t o long-ter m measurement s wit h wind s blowin g bot h t o an d from th e roadways , an d th e vehicl e count s ar e total , no tpetrol-drive n only . I n London , th e proportio n o f diese l vehicle s i s usuall y abou t25% , an d assumin g thi s proportion , th e resul t o f Musket t(1978 ) i s equivalen tt o x = 2 u g u T pe r100 0 petrol-drive n vehicle s pe rhour . Th

e result s o f

Tabl e 3. 2 ar e reasonabl y concordant . Th e normalise d concentratio n x Pe r100 0 vehicle s pe rhou ra tleve l an d no tbadl y constricte d sites , i s abou t3 ug m ~ whe n downwin

d measurement s ar e made , an d abou t2 M g m ~ i n long-ter m measurements . A tgrade d an d constricte d site s X i s increase d and ma y b e a s hig h a s 1 0 ug nf " . (b ) Measurement s i n car s Beva n e tal . (1 9 74 ) foun d 1 5 pg/ m insid e aca rwit h close d window s whic h wa s drive n t o an d fr o betwee n junction s 3 and 4 on th e M 4 motorwa

y fro m i10 0 t o 150 0 hour s on 5.10.77 . Th e concentratio n was 76 % o f th e concentratio n i n th e centra l reservatio n a tth e time . A numbe ro f carborn e measurement s wer e obtaine d i n th e presen twork , and th e result s ar e summarise d i n Tabl e 3.3 . Al l th e survey s wer e don e i n th e earl y afternoon . (c ) Variatio n o f

airborn e lea d wit h distanc e from roa d Table s 3. 2 and 3. 3 sho w tha tconcentration s o f 10-1 5 p g m

~ ca n b e foun d o n motorways , and concentration s o f abou t5 u g m i n ver y bus y street s i n London . I ti s importan tt o conside rho w ra rth e zon e o f

hig h lea d concentration s extend s o

n eithe rsid e o f

abus y road . Fig . 3. 5 show s th e concentratio n gradien twit h distanc e from th e edg e o f th e roadway . Th

e calculation s o f

Chamberlai n e tal . (1978 ) too k int o accoun t th e effect s o f

vertica l dispersio n i n averag e meteorologica l conditions , bu tmad e n o allowanc e fo rlos s o f P b b y deposition . Th e experimenta l point s o rBeva n e tal . (1974) , Hogbi n and Bevan (1976 ) and Littl e and Wiffe n (1978 ) ar e derive d fro m survey s besid e th e M4 . A loca l backgroun d o f 0. 4 u g m~

S ha s bee n deducte d

-19 -P.2 1

fron . u. e insure d concentrate , v.... ; bofc-r e repressin g the m o n apercentag e o f th e valu e a ttn e roa d (centra l r« c ir-.-'.tio n ;'o rBeva n e tal . an

d Hoghi n an d Bevan . har d shoulde rfo rLittl e an d Wiffen) . Hickma n (1976 ) measure d concen tration- » i n th e Cromwel l Roa

d and a tsite s dow

n asid e road , 20 , 3 0 and 5 0 m away . The concentration s wer e 4.1 , 3.0 , 2. 5 and 1. 2 ug m " respectively . Assumin g a backgroun d o f

0. 6 u g m

~ , th e declin e i n concentratio n wit h distanc e i s simila r t o tha ti n Fig . 3.5 , bu tth e result s hav e no tbee n include d a s th e samplin g a t th e 4 site s wa s no tsimultaneous . Walle re tal . (1965 ) foun d averag e yearl y concentration s i n 1962- 3 o f 3. 2 ug m

~ i n Flee tStreet , 0. 8 ug m " i n Mitr e Cour t 4 6 m away , an d 0. 8 u g m " als o a tSt.Bartholomew' s Medica l College , whic h i s no t nea rt o amajo rroad . Thus th e exces s concentratio n fro m Flee tStree ttrafri c was inappreciabl e a tMitr e Court . Assumin g rro

m th e consensu s o rresult s i n Tabl e 3. 2 tha tth e long-ter m averag e normalise d concentratio n x a tth e ker b o raleve l roa d i s 2 p g m * pe r 100 0 petrol-drive n vehicle s pe rhour , an d usin g th e theoretica l declin e o rx wit h distanc e i n Fig . 3.5 , th e widt h o rth e stri p o n eithe rsid e i n whic h th e contri butio n t o airborn e P b exceed s 1 ug m

~ i s abou t1 5 m ro raHo w o r100 0 Vh " , 5 0 m fo r200 0 Vh " and 10 0 m fo r400 0 Vh " , al l expresse d a s 24-hou raverag e flows . Ther e i s likel y t o b e considerabl e variatio n accordin g t o th e loca l topography . Hogbi n an d Beva n (1976 ) measure d lea d concentration s i n house s nea r th e M 4 wher e th e trafri c average s nearl y 400 0 vehicles/hr . I n continuou s 14-da y samples , 4. 8 ug m

~ was roun

d insid e abungalo w 3 4 m from th e edg e bea m o f th e motorway . A daytim e concentratio n o f 3. 0 u g m

~ wa s foun d i n ahous e a tsimila r distanc e i n th e presen twork , compare d wit h 5. 0 p g m ~ outsid e th e house . However , i n ahous e a t5 8 m designe d wit h n o openin g window s facin g th e motorway , Hogbi n and Bevan foun d onl y 1. 1 u g m ~ . I n ahous e immediatel y adjacen tt o an elevate d sectio n o f

th e M 6 i n Birmingha

m (abou t200 0 petrol-drive n vehicle s pe r hour) , th e concentratio n wa s 0.6 9 u g m ~ , and i n anothe rwit h doubl e glazin g i t wa s 0.4 4 u g m

~ (Departmen to f

th e Environment , 1978) . Tti e leve l insid e bot h house s was 6 0 t o 70

% o f tha toutside . Th

e elevatio n o rth e motorway s i n thi s par to rBirmingha

m assist s i n th e electiv e dispersio n o rexhaust . A tth e othe r extreme , Lawthe re tal . (1973 ) foun d 3. 7 p g m ~ insid e ahous e adjoinin g agrade d roa d constricte d b

y building s and carryin g abou t120 0 petrol-drive n vehicle s pe rhour . (d ) Urban and suburba n site s no tadjacen tt o mai n road s Measurements wer e mad e a tChelse aCollege , London , a tadistanc e o f abou t 10 0 m from eac h o f

3 mai n roads . Tw o samplin g position s wer e used , on e a t groun d leve l and th e othe ro n th e roo f a t2 5 m

. The result s ar e summarise d i n Tabl e 3.4 . Ther e was onl y slightl y les s P b i n ai ra t2 5 m compare d wit h groun d level , indicatin g tha temission s ove ralarg e are aaccounte d Torth e concentra tions . O

n tw o fogg y day s concentration s ros e t o 1. 6 u g n f . Durin g th e week , nighttim e concentration s (23.0 0 - 07.0 0 h ) average d abou t65 % o f daytim e level s (07.0 0 - 23.0 0 hr) , bu ta tth e weekends , nighttim e concentration s exceede d day tirf e level s by afacto ro f 1.3 . Thes e result s ma y i n par treflec trecreationa l

-20 -P.2 2
populatio nmovement s withi nLondon . Measurement s wer e als o mad e i nresidentia l area s o f Readin g (populatio n132,000 ) and Didco t (11,000) , (Tabl e 3.4) . I n Didcot , th e concentration s wer e strongl y affecte db

y winddirectio n(Fig . 3.9) . Th e highe r concentration s associate dwit hwin dfro m easterl y

quarter s suggest s lon g rang e transpor t o f lea dfro m the greate r Londo narea , wit ha tim e dela y i n transpor t resultin g i n highe r nighttime concentrations . Wit hth e cleane r westerl y

airstream , nighttime concentration s wer e lowe r tha ndaytime level s Indicatin g greate r importanc e o f loca l lea dsources . (e ) Enclose dca r par k A s a n exampl e o f a specialise dsituation , measurement s of daytime P bcon centration s wer e mad e i n a poorl y ventilate dmulti-store y ca r park . Concentra -



### - 3 tion s varie d widel y between 1 2 an d 4 0 u g m accordin g t o th e degre e o f ventila tio n an d th e volixne o f

traffi c enterin g an

d leavin g th e ca rpark . Mos tmember s o f th e publi c ar e expose d t o thes e concentration s fo ronl y afe w minute s whils t parkin g an

d drivin g awa

y thei rcars . Measurement

s wer e als o mad

e o f th e level s o f

0 0 i n th e ca rpar

k usin g a Mira n II I infra-re d ga s analyse ran d Draegertubes . Daytim e level s varie d between 5 0 an

d 30 0 ppm

. Organi c lea d vapourwa s als o measure

d usin g th e metho

d o f Hancoc k an d Slate r(1975) . Level s o f 1. 5 an d 5. 4 u g m ~ organi c lea d vapour wer e measure

d o n tw o occasions . Purdu

e e tal . (1973 ) foun

d organi c lea d concen tration s o f

1. 8 - 2. 2 u

g m ~ i n a n undergroun

d ca rpark . I n th e presen tstud y th e organi c P

b represente d 10. 0 an

d 12.8 % o f

th e tota l inorgani c particulat e an d organi c Pb . Thes e percentages compar e with th e 15-18% observe d b y Purdu e e tal . (1973) . Foranumbe

ro f ope n ai rlocation s i n London , Harriso n e tal . (1974 ) foun d value s between 0. 1 an d 4.0% , risin g t o 9.7 % adjacen tt o petrol-fillin g stations . 3. 6 Particl e siz e analyse s (a ) Objective s an

d method s Th e particl e size s o f

ambien tlea d aerosol s wer

e analyse d i n orde rt o (i ) ensur e tha tinhalatio n experiments wit h artificiall y generate d P b aerosol s wer

e representativ e o f

lea d exhaus taerosol s i n th e environ ment . (ii ) correlat e th e result s o rinhalatio n experiments o n th e ambien

t aeroso l I n variou s locations , describe d i n th e followin g secUon . (iii ) se e I f

mor e than on e sourc e contribute d t o th e aerosol , fo rexanple , re-suspende d dust . Th e method s o f analysi s fal l int o tw o groups . Impactio n an d diffusion batter y device s separat e th e aeroso l int o fraction s which ma y b e analyse d fo r lead . Th

e particl e siz e spectru m ha s the n t o b e deduced fro m th e characteristic s o f th e samplin g device . Th e resul trefer s t o th e lead-carryin g particles . Optica l method

s ar e mor

e exac tbu tmor

e tedious . A larg e numbe ro f particle s has t o b e size d fro

m micrographs . A

s i ti s no tusuall y possibl e t o distinguis h

-21 -P.2 3

th e lead-tearin g particle s wit hcertainty , optica l method s giv e th e particl e siz e spectru

m o f al l particles . Anderse nimpacto r sampler s hav e 8 impactio nplate s an da backin g filter . Th e aerodynami c equivalen t particl e siz e (50 % cut-ofr ) i s 0. 3 p m o nth e fina l plat e andsmalle r particle s penetrat e t o th e filter . Result s obtaine dwit h Anderse nsampler s ar e usuall y plotte do nlogarithmi c probabilit y paper . I f th e logarithm s o f th e particl e diameter s ar e normall y distributed, th e plo t come s ou t a s a straigh t line . Th e mas s media nequivalen t aerodynami c diamete r (MMED ) i s the nrea dor r fro m th e plot . I f a considerabl e fractio no f the particle s penetrate s t o the backin g filter , a s occur s wit hleadexhaus t aerosols , thi s procedur e ma y

fai l t o revea l tha t th e distributio ni s no t logarithmicall y normal , bu t i s bimodal , wit htw o separat e population s o f particles . Thi s i s ofte nfoun d t o b e the cas e wit hambien t aerosols . Whitby e t al . (1975 ) usin g a nelectrica l particl e analyse r foun dtha t fres hfreewa y aeroso l sample da t 3 0 m wa s mostl y below 0.1 5 p m i ndiameter . I nth e presen t work , abou t 67 % o f th e P bi nmotorwa y sample s penetrate dt o th e backin g filte r o f the Anderse nsampler . Thu s i t i s apparen t tha t aeroso l sample dnea r t o rapidl y movin g vehicle s i s to o fine t o be characterise dadequatel y b y impactio nsamplers . Th e diffusio nbatter y i s a chambe r wit hparalle l plate s a t a separatio no f 0. 8 m m throughwhic hth e aeroso l i s passed . Th e concentratio no f leadi nth e ai r i s measure dbefor e an dafte r passag e throug hth e battery- , an dth e rati o o f concentratio nuse dt o deduc e a mea nparticl e siz e b y th e metho do f Metniek s an d Polla k (1959) . Th e resul t i s calle dth e difrusiona l mea nequivalen t diamete r (DMED) . A s the Brownia ndirrusivit y o r a particl e depend s onsiz e an dshap e bu t no t ondensity, the particl e siz e determine dfro m th e diffusio nbatter y ca n b e compare dwit hthe optica l size . A therma l precipitato r wa s use dt o sampl e aerosol s fo r electro nmicroscopy , th e particle s bein g deposite ddirectl y ont o a nelectro nmicroscop e grid . Th e particle s o nth e micrograph s wer e size di nterm s o f th e Fere t diamete r (th e distanc e betwee ntangent s a t th e extremitie s o f the particl e perpendicula r t o a fixe ddirection) . (b ) Motorwa y

aerosol s Th e particl e siz e spectru no f a'rborn e P bbesid e th e M 4 a s measure dwit hth e Anderse nsampler , i s show ni nTabl e 3.5 . Ver y littl e P bwa s associate dwit h particle s greate r tha n5 pm , althoug hth e wor k o r Habib i (1973 ) suggeste dtha t a substantia l proportio no r emitte dP bwa s greate r tha n5 pm . Th e Anderse n sample r doe s no t operat e isokinetically , andwa s possibl y failin g t o sampl e th e large r particles . Placin g i t wit hth e entr y por t facing int o the wind , s o tha t an y larg e particle s woul dten dt o b e over-estimated , mad e n o differenc e t o th e percentag e o f P bassociate dwit hparticle s greate r than5 pm . A furthe r chec k o nlarg e particle s wa s mad e usin g a cascad e centripete r (Houna m an dSherwood , 1965) . Again , no t mor e tha n10 % o f the airborn e lea dwa s associate dwit h particle s exceedin g abou t 2 p m diameter , wit habou t 90 % o f th e leadbein g

-22 -, collecte db y the fina l stag e o f th e centripeter . A fractio no f th e 33 % of airborn e Pbsample dnea r th e M 4 whic hwa s foun

don th e impactio nstage s i s attributabl e t o diffusiona l depositio no f ver y fin e materia l wel l belo w th e minimu m siz e fo r impaction . Clearly , th e impacto r result s als o indicat e a mas s media nequivalen t diamete r o f les s tha n0. 3 p m besid e the motorways . Melto n e t al . (1973 ) an

d Mora ne t al . (1972 ) als o foun dtha t 6 9 and 66 % o f th e exhaus t particle s wer e les s tha n0. 3 p m diamete r unde r stead y cruis e conditions . Electro nmicrograph s o f th e aeroso l a s sample dbesid e th e M 4 ar e showni n Fig . 3.6 . Thre e type s of particle s ca n b e distinguishe da s categorise di n Tabl e 3.6 . Th e primary particle s o n th e electro nmicrograph s ar e discrete , compac t an

d ver y electro ndense , s o tha t eve na t th e 60,00 0 * magnificatio n required the

y coul d be size

d readil y

- categor

y 1 . Categorie s 2 an d 3 wit h 

### thei rmuc

h lowe rfrequency wer

e examine

d a t8,00 0 x an

d 2,00 0 x respectively . I n Fig . 3. 7 aparticl e siz e spectru m obtaine d b

y visua l examinatio n o f particle s i s shown. Th e ordinat e i s th e incrementa l numbe ro f particle s pe r c m o f ai rpe rincremen ti n lo g radius . Simila rsiz e distribution s wer e obtaine d b

y th e M40, th e siz e distributio n remainin g substantiall y unaffecte d b y th e incline . Th

e appearanc e o f

th e aeroso l i n th e electro n micrographs suggeste d tha tth e smalles tcategor y carrie d mosto f th e lead . Thi s wa

s confirmed b

y comparin

g th e volumetric-mean-diamete r (VMD ) o f thi s categor y determined visuall y fro m th e number-siz e distributio n wit h th e mea n diamete rdeduce

d fro m th e diffusio n batter y results . Thi s i s show n i n Tabl e 3.7 . Wit

h on e exceptio n (ru n o f 16.9.76 ) th e tw o estimate s o f VM D ar e compatible . Result s obtaine d wit h th e diffusio n batter y indicate d aAM D o f abou t0.0 3 p

m fo rboth th e M

4 an d M4 0 motorways . Wilso n e tal . (1977 ) use d a n electrica l aeroso l analyse rfo rstudyin g ca rexhaus temission s o n ates ttrad: . The y als o foun

d thre e principa l categorie s o f particles , thes e i n th e "nucle i mode" (geometri c mea

n diamete r0.01 8 pm) , th e "accumulatio n mode" (0.2 1 pm ) an d "coars e particl e mode " (4. 9 pm) . The y observed

tha tcar s drive n a tnorma l speed s emi taerosol s mainl y i n th e "nucle i mode" , an d tha tcoagulatio n withi n thes e aerosol s an

d coagulatio n wit h othe raerosol s transfer s thes e particle s t o th e "accumulatio n mode" . Th e findin g tha tlea d nea rmotorway s i s mostl y i n th e "nucle i mode" ha s importan timplication s fo rth e rat e o f depositio n o

n surface s an d th e uptake i n th e lung . (c ) Urban , suburba

n an d rura l area s Whe n car s ar e subjecte d t o urba n drivin g schedule s o

n dynamometers , amarke d shif ttowar

d large rparticl e size s occur s (se e fo rexample Mora n e tal . 1972 , Habibi 1973) . I n th e presen tstudy , measurement s o f particl e siz e were mad e besid e th e Hogart

h roundabou

ta tChiswick t o observ e th e effec to f period s o f heav y acceleratio n o

n th e emission s o f

particle s i n th e coars e particl e mode. Th e Anderse n impacto rresult s showe d a n increas e o f

th e percentages o f

P b associate d wit h particle s i n both th e accumulatio n an d coars e particl e modes , wit h onl y 30

% penetratin g t o th e filte rstag e compare d wit h 67

% o n th e M4 .

-23 -P.2 5

Besid e th e roundabout , a ne w pea k i nth e particl e siz e distributio n*« s eviden t wit h4? % o r th e P bbetwee n1. 0 and4. 2 M m aerodynami c Jiar?. . t•• r (Tabl e 3.5) . I t i s no t possibl e t o us e th e diffusio nbatter y meaningfull y

..lie nther e ar e man y larg e particles, unles s thes e ar e remove dfirst . Consequently , th e Anderse n impacto r wa s modifie dt o ac t a s a "pre-impactor " wit hth e backin g filte r replace db

y a diffusio nbatter y ru ni nserie s wit hth e impacto r stages . Th e diffusio nbatter y

reveale da mea ndiamete r o f 0.05 4 u m fo r th e 30 % o f th e P b whic hwa s les s tha n0. 3 u m andpenetrate dth e Anderse nimpactor . A noveral l mas s media nequivalen t diamete r (MrtED ) o f abou t 2. 0 u m i s indicate dbesid e th e roundabout , compare dwit h0.0 3 - 0.0 4 p m b y th e M4 . Therma l precipitato r sample s wer e als o take nfo r examinatio nb

y electro nmicroscopy . Fig . 3. 8 con trast s th

e aeroso l particl e siz e spectru m wit htha t o f th e M4 . Bot hFigs . 3. 7 an d3. 8 refe r t o al l particle s i nth e aerosol , no t solel y lead-bearin g particles . Th e decreas e i nnumbe r o f particle s i nth e nucle i mode , andincrease s i nth e accumulatio nandcoars e particl e mode s besid e th e roundabout , ar e evident . Carbom e measurement s wit hAnderse nimpactor s alon g th e Nort han dSout hCircula r road s an daroundmajo r street s i nHammersmit han dChiswic k gav e a particl e siz e distributio nintermediat e betwee nthos e o f th e M 4 andth e roundabou t (Tabl e 3.5) . Th e "vME D wa s abou t 0. 3 p

m wit h51 % o f the P bassociate dwit hparticle s o r les s tha n0. 3 pm . Th e pea k betwee n1 an d4 p m observe db

y the rewndabou t wa s stil l evident , bu t muc hles s marke d(25!%) , wit hslightl y highe r percentage s i nth e accumulatio nmod e (0. 3 - 1 um ) tha nfoun donth e motorway . A simila r siz e dis tributio nwa s observe di nth e street s o f Reading . Thes e Observation s ar e simila r t o thos e o f Chola k e t al . (1968) , Robinso nandLudwi g (1967) , andLe e e t al . (1971) , wh o use dimpactor s i nurba nsituation s anddemonstrate dMvtE D o f P baerosol s o r 0. 3 pm , 0.2 5 p m and0.1 8 p

m respectively . Biggin s andHarriso n (1978 ) obtaine dsomewha t large r MMED s o r 0. 7 and0. 8 p m wit hAnderse nsampler s a t variou s location s i nLancaste r andPreston , a siz e intermediat e betwee nth e bus y urba nan

droundabou t sample s o r th e presen t study . Particl e siz e measurement s wit hAnderse nimpactor s wer e als o ned e a t Chelse a College , anda t Count y Hall , Westminster , wher e th e P baeroso l i s probabl y typica l o r larg e area s o r Londo nbeyondth e immediat e influenc e o f th e nearby streets . N o significan t difference s wer e observe di nparticl e size s betwee nthe roo f andground-leve l site s a t eithe r location . A s i nth e Londo n streets , th e »WE D wa s abou t 0. 3 um , wit h57 % penetratin g u> !.»•• • Uwk.uy, l'U*«- i durin g th e sunme r an d51 % durin g th e autum n(Tabl e 3.5) . Fo r th c period s o f sampling , thi s seasona l difTerenc e wa s no t signiricant . Th e overal l siz e distri butio nwa s ver y

simila r t o tha t o r th e Londo nstreets , wit hthe pea k i nlarg e particle s observe dbesid e th e roundabou t agai nbein g absent . Unde r fogg y condi tion s i nOctober , however , onl y 40 % o f th e P bpenetrate dt o th e backin g pape r and th e ver y sligh t pea k around1 p m note di nbot hsumme r an dautum nsample s became a muc hbroade r pea k wit h48 % o f th e P bbetwee n0. 3 and2 p m aerodynami c diameter . Thi s ma y

hav e bee ncause db

y hygroscopi c growt ho f particle s o r t o greate r aggre gatio ni nth e poorl y dispersiv e conditions . Eve ni ndry conditions , usin g a

-24 -P.2 6

^irfusio nbatter y

A nserie s wit ha nAnderse nimpacto r a s a pre-lmpactor , the diffusio nmea ndiamete r o f the P bparticle s penetratin g the Anderse nimpacto r wa s 0.06 4 i 0.0 2 pm , suggestin g som e aggregatio no f the fines t exhaus t particles . Th e aeroso l a t Qielse a Colleg e probabl y ha s a comple xstructur e o f bot hfres hand age dexhaus t component s whic hhav e bee nemitte dunde r a wid e rang e o f drivin g condition s an

dhav e undergon e varyin g degree s o f aggregatio nanddeposition . I nth e house , 5 0 m

fro m th e M4 , usin g th e difrusio nbatter y withou t th e Anderse n pre-lmpacto r gav e a diffusio nmea ndiamete r o f 0.0 7 p m compare dwit h0.0 3 p m o n th e har dshoulder , agai nsuggestin g aggregatio nandattachmen t o f th e 0.0 3 p m primar y exhaus t particle s andtransfe r o f P bfro m th e "nucle i mode " t o the "accumulatio nmode" . However , diffusiona l depositio no f th e smalles t particle s aroun ddoor s an dwindow s ma y hav e cause dsom

e o f the depletio no f th e smalles t particle s insid e th e house . A s a nexanpl e o f a matur e age daerosol , particl e siz e measurement s wer e als o mad e i nrura l Oxfordshir e (Tabl e 3.5) . Thi s aeroso l wa s ver y simila r t o tha t foun

da t Chelse a Colleg e i nfog , wit h37 % penetratin g th e Anderse nimpactor , anda broa dpea k betwee n0. 3 and1. 0 pm . Thi s probabl y represent s aggregatio n andattachmen t o f primar y exhaus t P bt o the ambien t aerosol . Thes e dirrerence s i nparticl e siz e ar e relevan t t o th e rate s o r P bdeposi tionsinc e th e velocit y o r depositio no r particle s reache s a minimu m betwee n 0. 2 and0. 5 p

m andincrease s steepl y wit hbot hincreasin g an ddecreasin g particl e siz e (Littl e andWirren , 1977) . Thi s applie s no t onl y t o depositio nt o th e groun dsurface , bu t als o t o the depositio no f P bi nth e lung s followin g inhalation . (d ) Enclose dca r par k Th e particl e siz e distributio no f a concentrate daeroso l o f mediu m ag e fro

m vehicle s i na nenclose dca r par k wa s als o measure dwit hAnderse nimpactor s and diffusio nbatteries , an db y electro nmicroscopy o f therma l precipitato r samples . Anderse nsample s agai nshowe dabou t 50 % penetration , givin g a &ME D o f abou t 0. 3 p m simila r t o urba nLondo n(Tabl e 3.5) . Us e o f the diTfusio nbatter y i n serie s wit hth e Anderse nimpacto r showe da diffusio nmea ndiamete r o f 0.0 8 p m fo r th e P bparticle s penetratin g th e Andersen . Thus , th e particl e siz e distri butio nwa s simila r t o tha t observe dfo r th e urba nLondo nstree t aerosols , wit h som e degre e o f aggregatio no f primar y exhaus t an

dtransfe r fro

m th e "nuclei " t o th e "accumulation " mode . 3. 7 Chemica l compositio no f exhaus t lead On e o f th e problem s i nth e chemica l characterisatio no r exhaus t P bi s tha t change s occu r aTte r emissio nt o th e atmosphere . A furthe r problem

i s tha t th e smal l siz e o f the particle s preclude s effectiv e us e o f electro nmicroprob e techniques . Mos t studie s howeve r hav e reporte dcomple xmixture s o f leadoxides , halide s and ammoniu m salts , togethe r wit hsulphate s an dcarbonaceou s materia l (e.g . Habibi , l'»73) . Som e o f the mos t recen t Britis hwor k b y Biggin s andHarriso n(1978) , usin g X-ra y powde r diffractio nindicate s th e persisten t presen t o f (NH 4 ) 2 S0 4 . PbS0> 4 , togethe r

-25 -P.2 7



### with lesse ramount

s o f PbS04 

### an

d PbBrCl. The

y believ e tha t(NH 4 

### ) 2 

### S0 4 

### .PbS0 4 

### i s a n intermediat e i n th e conversio n o f vehicle-emitte d lea d halide s t o PbS0 4 

### , forme d b y reactio n wit h atmospheri c ammoni aan d aci d sulphates . Th e solubilit y o f

th e compoun d i s intermediat e between tha to f th e sparingl y solubl e oxide s an d th e mor

e solubl e halide s an

d nitrates . O

n accoun to f

it s smal l particl e siz e i ti s likel y 203 t o be readil y solubl e i n th e lung , sinc e inhalatio n experiments wit h Pb O aerosol s showe d rapi d uptake o f

P b fro m th e lun g int o th e bloo d stream (se e Sectio n 6 below) . I n th e presen tstud y acontinuou s flo w solubilit y techniqu e usin g aeroso l parti culate s collecte d o

n 'absolute ' filter s has show n tha tth e lea d associate d wit h motor exhaus taerosol , whetherfres h o raged , i s extremel y solubl e i n distille d wate ra t 20 C . Unde

rsimila rcondition s th e lea d associate d with lea d oxid e aerosol s dissolve s muc

h mor e slowly . Fo rexample , fo rmotorexhaus tlea d 92 % dissolve d i n 1 m

l wate rflowin g fo r2 minute s wherea

s fo rlea d oxid e onl y 11 % dissolve d i n 4 0 m

l wate rflowin g fo r9 0 minutes . Increasin g th e temperature t o blood-hea t(3 7 C ) an d usin g bloo d plasm

aa s th e solven traise d t o 19

% th e lea d dissolvin g i n 9 0 minute s fro m th e lea d oxid e aerosol .

-26 -I TABL E 3. 1 Lead depositio n rate s a tvariou s location s
Locatio n Rura l site s U.K . Urban site s Pasaden a Sa n Dieg o Pal o Alt o Cincinnat i Ne w York Chicag o (airport ) London , Hesto n (semi-rural ) Smelte rsite s E l Pas o (0. 1 km

) Toront o (0.1 5 km

) Avonmout

h (0. 1 km

) " ( 1. 0 km

) " (3. 0 km

) Roadsid e site s 1 0 m from roa d wit h 4,00 0 vehicle s hr ~ 1 5 m from roa d (Pal o Alto ) 1 m fro m roa d wit h 62,00 0 car s day" ' 3 0 mi ti tI I I I I I I I 15 0 m " " " " " " Centra l reserv e o f

M 4 0 m from har d shoulde ro f M 4 5 m " " " " " 1 5 m " " " " " 3 0 m " " " " " P b depositio n rat e (mg nr 2 day - 1 ) 0.0 2 - 0.1 7 ' 0.4 5 0.0 7 - 0.9 5 0.3 7 0.3 5 - 3. 2 0.1 4 - 1. 4 0.4 6 0. 2
7 1 8 5. 0 - 11. 5 0. 5 - 4. 0 0. 4 - 1. 0
3. 2 1. 4 23. 0 1. 5 1. 0 1 0 - 1 6 6-1 5 2. 3 - 6. 2 1. 1 - 3. 1 0. 6 - 1. 8 Depositio n surfac e

Deposi tgaug e Deposi tgaug e Deposi tgaug e Pa n Deposi tgaug e Deposi tgaug e Polythen e bucket s Soi l an d gras s Deposi tgauge s

~ Deposi tgauge s Deposi tgauge s Deposi tgauge s Deposi tgauge s
Sedimentatio n Jar s Pa n Deposi tgaug e Deposi tgaug e Deposi tgaug e Gras s an d soi l . Gras s an d soi l Gras s an d soi l Gras s an d soi l Gras s an d soi l Referenc e Caws e (1974 )
Huntzicke re tal . (1975 ) Cho w (1 9 70 ) Atkin s (1969 ) Chola k e tal . (1968 ) Volcho k e tal i (1974 ) Lazru s e tal . (1970 ) Thi s wor k Landriga n e tal . (1 9 75 ) Robert s e tal . (1974 ) Littl e (1974 ) I I i t I I I I
Chola k e tal . (1968 ) Atkin s (1969 ) Frledlande r* Huntzicke r(1974 ) i ti tn ti n i t Littl e S Wiffe n (1978 )

• i I I • • I I I I n n « » I I I I • •TABL E 3. 2 Measurement s o T lea

d inai r besid e motorway s and othe r street s



# f Locatio n

M 4 centra l reservatio n M4 , 2 m Tro

m edg e bea m M40 , 2 m frc m edg e bea m leve l 1/2 0 grad e i n cuttin g l/2 0 grad e o n embankmen t Theoretica l resul t London , Flee tStree t Centra l reservatio n Heat h Road , Hampstea d (o n hill ) Exhibitio n Road , S.W. 7 (kerbside ) Seymou rPlace , W. 1 Talgart h Road , W. H Uppe rBerkele y Street , W. I

, Variou s site s ; Rome , 4 site s Ope n o r constricte d sit e 0 0 0 C 0 0

C C 0

C 1 0 

## c

mm

- Samplin g

period s
24-hou r Daytim e n

I I

n

I I
Daytim e 24-hou r Daytim e 

# i"

• I

• I 24-hou i Petro l

Vehicle s pe rhou r 380 0 360 0 97 0 95 0 99 0

-
120 0 120 0 130 0 42 4 388 0 42 0 Lea d i n a

Measure d 15. 1 8 . 9 3 . 3 10. 3 6 . 4

-
3 . 2 5 . 3 3 . 2 4 . 0 8 . 8 4 . 3 1
• statistica l surve y (al l vehic l es ) i r(u g m" - ) Backgroun d (estimated ) 0 . 4 0 . 4 0 . 2 0 . 2 0 . 2

-
0 . 8 0 . 4 0 . 5 1. 0 0 . 5 1. 0 - 3

p g m pe r 100 0 Vh- '
3. 9 2 . 4 3 . 2 10. 0 6 . 2 3 . 3

2 . 0 4 . 1 2 . 0 7. 1 2 . 2 7. 9 1. 5

1. 8 Reference s

Beva n e tal . (1974 ) Littl e an d Wifre n (1978 )
i tt i I I I I

I I i tt tt i

i i i tI I i t Chamberlai n e tal . (1978 )

Walle re tal . (1965 ) Lawthe re tal . (1973 ) Harriso n e tal . (1974 )
i ti ti t
I I i t• •
t tI I i t Musket t(1978 )
Colacin o k Lavagnin l

( 1974 )"TwrT^ T m>1fr P.3 0

TABL E 3. 3 Measurement

s o f airborn e lea d i n carbom e survey s

Locatio n
M 4 betwee n junction s 2 an d 5 Nort h and Sout h Circula rroad s A 4 betwee n Chiswic k an d Hammersmit h Readin g street s No . o f run s 4 2 3 1 P

b concentratio n Mg/m 3 11. 5 5. 7 5. 2 2. 1

TABL E 3. 4 Measuremen

to f airborn e lea d a trixe d site s (24-hou rresults )

Locatio n Chelse aColleg e Groun d leve l Roo r Roo r Roo r Readin g Didco t London , County Hal l

London , St.Bartholomew' s Hospita l Dat e

Jul y 1977 Jul y 197 7 Sept/Oct . 197 7 Jul y 197 8 Ma y 197 8 Ma y 197 8 Jul y 197 8 1975/6 , summe

r 1975/6 , winte r 1971/ 2 P

b concentratio n M « m~ 3
0.4 6 0.3 9 0.8 0 0.4 6 0.3 5 0.2 0 0.1 9 0.5 0 1.0 6 0. 6 Referenc e

Thi s wor

k t i i t

n t t t ti t
t i i t
i tt i
i tt i Bal l & Hum

e (1977 ) i tI I Lawthe re tal . (1973 )

-29 -P.3 1

TABL E 3. 5 Pe-ticl e siz e

50 % cutof rdiam . u m 11. 5 9 . 5 5. 7 4 . 2 2. 2 1. 0 0. 5 0 . 3 <0. 3 M4E D (um ) CMED * (pm )

KWE D (pm ) tMED * (pm )

i



## 1 !
t 

## i i 1 1

fcMED (pm )

CMED * (um ) analysi s o rairborn e P b measure d wit h Anderse n J.mpact o (Mea n percentag e o n eac h stag e i S.D. )

M 4 * 1.5 9 1.8 3 3.1 0 4.3 9 4.9 5 4.8 7 7.2 4 4.7 4 67.3 8 0.0 4 0.0 3 S.D .

0.6 0 0.3 4 0.6 5 1.1 4 0.6 7 1.0 8 5.0 1 0.9 9 2.1 3

Chelse aColleg e (summer ) 3.7 2 2.2 4 4.5 4 5.3 4 5.9 6 7.7 8 6.7 8 6.4 0 57.2 3 0.2 2

- 2.3 6

0.7 9 2.0 1 1.9 4 1.7 6 2.3 5 4.5 0 2.2 7 7.0 5

Rura l Oxfordshir e 2.8 1 2.4 6 3.0 7 4.2 0 6.1 0 12.3 7 14.3 9 17.3 7 37.2 3 0.2 2

- 0.5 9

0.3 6 0.5 7 0.6 4 1.6 7 1.5 3 3.1 0 5.4 3 4.3 6 Hogart h roundabou t

% 6.6 6 4.6 1 6.5 3 14.5 2 14.1 6 13.7 5 4.7 6 2.5 9 30.4 7 2 . 0 S.D .

0.6 1 0.9 8 0.6 1 0.9 4 1.0 6 0.5 9 0.8 6 0.5 2 2.5 2

0.05 4 Chelse aColleg e '(autumn ) 2.4 1 2.3 6 4.2 4 4.1 9 7.6 3 10.0 2 6.8 6 0.7 7

0.6 9 0.6 0 0.8 3 1.1 9 1.3 3 1.9 4 8.0 6 j 2.4 3 51.2 7 ; 5.8 9 0 . 3 | 0.06 4
Enclose d ca rpar k 2.7 1 2.7 7 4.3 0 7.4 2 8.4 2 10.6 0 5.6 2 5.0 8 53.1 9 0 . 3 1.0 4

0.7 7 1.2 2 1.9 0 1.7 4 0.9 4 1.6 2 2.0 3 3.3 6
0.0 8 | r s
Londo n street s * 2.7 7 2.7 7 3.6 2 5.7 7 7.7 5 11.1 1 6.3 2 9.0 1 50.8 9 0 . 3

- S.D .

0.6 1 0.6 1 1.2 6 2.1 4 1.6 1 2.6 4 1.1 0 4.2 7 2.4 4

Chelse aColleg e (fog ) 1.9 6 1.3 8 3.8 2 6.0 5 10.2 0 15.7 0 10.3 8 11.5 8 0.3 6

0.4 5 0.0 0 1.0 3 1.7 3 2.4 5 0.5 6 1.3 9 39.8 0 8.2 1 0 . 5 " Laborator y <1.0 0 <1.0 0 <1.0 0 <1.0 0 <1.0 0 - i

- 28.4 0 - 5.1 9 56.1 6 7.5 2 j 13.6 4 2.7 1 i <1.0 0

—

- 

### O f th e fractio n penetratin g t o th e filte rstage .
-30 -TABL E 3. 6 i 

### Categorie s o rparticl e i n electro n micrograph *
Categor y 1
2 3 Siz e

p m <0. 1
0.1-1. 0 0.5-5. 0 Appearanc e

Opaque discrete , rounde d Diaphanous , chai n aggregate s Dense , flak y o ramorphou s Suppose d origi n Primar y lea d particle s produce d i n engin e Mostl y diese l smok

e Carbonaceou s particle s fro m tail-pip e o r adventitiou s particle s fro m distan tsource s o r re-suspende d fro m roa d



### TABL E 3. 7 Volumetric-mea

n particl e diameter s

Motorwa y

M 4

M40 , inclin e

M40 , leve l 1 Mea n o f leve l site s Dat e

13.10.7 5 16.9.7 5 17.6.7 6 1.7.7 6 12.6.7 6 8.9.7 6 29.10.7 5 26.11.7 5 13.4.7 6 26.5.7 6 Particl e siz e (um ) Diffusio n batter y (CMED )

_ 0.0 3 0.03 5 0.0 3 0.0 3 0.04 5

-

- 0.0 3 0.0 3 0.03 3 Fro m electro n micrograph s (VMD

) 0.02 4 0.0 8 0.05 2 0.04 5 0.04 8 0.04 2 0.01 4 0.02 1 0.02 0 0.01 6 0.04 4

-SI -"T;-TT»T- 7 n|ffTf' •

~ \
^

AER E - R 919 8 Fig . 3. 1 M 4 motorwa

y a t Hesto n

3 2» 1 9 1 8 1 7 I S I S H 1 ] 1 2 I I 1 0 •

. t 7 6 5 4 1 2 1 WIN O DIRECTIO N

i I I I I 

# i /

/ / / / 

## .-—^ g ^';- 

### « t

m 

# i s 6

5 m Hor

O rtoulotr CwMro l (•MTVQtio n Mora »houl<»» r S

m 15

m 30 m

AER E •R 919 8 Pig . 3. 2 Concentration s o f P b I n ai r an d rates o f P b depositio n t o gras s acros s th e M 4 motorwa y

-33 -AER E - R 919 8 Fig . 3. 3 M4 0 motorwa

y

- 3 4"Tf* • !••"TT1T " "

AER E - R 919 8 Fig . 3. 4 Hogart h roundabou t

-35 -P.3 7



### 10 0

T O 

### In ** o o o

c o

c o c o u

0 ) 

### o c A) O t O l Q . 

### 1 0 - T

### i r 

# I ' ' ' ' I T—I—i— r



# 1 1 1 0 

## 5 0 100

Distanc e (m ) 15 0
AERE . R9198 . FIG . 3.5 . VARIATIO N O F CONCENTRATIO N WIT H DISTANC E FRO M MOTORWAY . x LITTL E & WIFFE N (1978 ) O BEVA N e t a l (1974 ) A HOGBI N & BEVA N (1976 ) ERRO R BAR S AR E 1 S.E .

THEORETICA L ( CHAMBERLAI N e t a l 1978 )

-36 -0. 1 p m 1 n.. m 4. 0 p m 1. 0 p m i r i

, »• • • , < Tv i ''•>•*•"»;,.»*,^ i & * " • 4 '";i- . ,.* . V i , . ; , t ^ *-- . '"•>*; • •••• : -v^*>'i*'' ^ a, -•-',;.'•"•> ' ;•

• . - #* •».-» r•*. ?
• « •••». - •• •'a, ,~• -a • . -J * _, . •*•• - • i** ; ; v-**^ * ••-•* " •-?•* ? ,• •:.• * x. . vv« . *..-,-••'.;*.', * ? ^ r - ' : v«- ' •<>*->-»^ ~ -"-•»•••'' •.Tr-.-v-'.-"--*'•=*•'•>• >

. ' a. .- V O.' ^
.. . » . .'' l ! —».-• > .• . mi a- '* • r Jf •'

• . I
. ^ * ,*.•• ' - . *
. * • am.


### ••:•: -• :im 

### .-:: : 

### ->'-4&'?^rr. 

# r--.---v*-*.-.:---'----*•- « % * . •** v

. V

2 Particl e categorie s
A typica l motorwa

y AER E - R 919 8 Fig . 3. 6 vehicl e exhaus

t aeroso l viewe d b

y electro n microscop

y at thre e magnification s-tp^ W yimTaafrJ-"TM!



# 10 6 

# L

E o * o . O l 

### o .T 3 

### 1 0

10 - h 1 0

1 0



## 1 0



# iL— L 10 " — i r M 4 HESTO N

Smal l opaqu e sphere s 

## Carbo n

chai n aggregate s Larg e

particle s 

# 1 1 0 - 2 _ L 

# ±

- 1 1 0 Diamete r ( ur n ) 1 0
AERE . R9198 . FIG . 3.7 . VEHICL E AEROSOLS . SI2 E DISTRIBUTION S

O F THRE E CLASSE S O F PARTICL E .

-38 -T T * '"•"•^nr1

•



### 10 *

5 1 0
c* > 

### £ u


### » 4
o o

'*•••"• " 

### • o •J* ?


## " io 3



### 10 2



### 1 1 0

1 l l | l

\ \ 

# '"V T -r—[ —

-



### — o M 4 Mo t

— x Hogart h

i il l 

# ° \ \



### orwa y round <



# . 1 - • * 1 j i •| i



# v \ \

\ N



### \ o V k \ \ r ? 

# V \ 

### ibou t V

\

\ 

## •f t

• \ \ \



# . 1 , 1 1 

# \ , ' :

**** *

_

-

_

M

-
•"* "

-

* ~

aa

ma

1 

## 000 1 00 1 1 0 10 0 0 1 1 Particl e diamete r (um ) A.E.RE.R9198 . FIG . 3.8. TOTA L PARTICL E SIZ E DISTRIBUTION S A T M 4 (HESTON ) AN D HOGART H ROUNDABOUT .

-39 -

# t 0 2 8
02 6
02 2

•a .

. o 01 8
0-1 4
0-10 -
0 06 - •Daytim e 07 M 

## -19 M



## x Nighttim e 19 M 

## -07° *

J L l

_ L W N

W N N E Mea n win d directio n ove r 72 h period s AERE . R9198 . FIG . 3.9 . LEVEL S OF AIRBORN E P b I N A SMALLTOW N ( DIDCOT . OXON ) COMPARISO N O F DAYTIM E AN D NIGHTTIM E LEVELS AN D TH E EFFEC T O F WIN D DIRECTIO N MAY - JUL

Y 1978 .P.4 2

4 . Inhalatio nof stabl e lead 4. 1 Method s o f measuremen t Th e ai m wa s t o measur e th e depositio no f inhale dPbi nth e lung s a t motorway , urba nan

dsuburba nlocations . I t wa s though t tha t difference s i nparticl e siz e woul d b e reflecte di npercentag e depositio ni nth e lung . Tti e metho dwa s t o measur e th e concentration s i nP bi ninhale dan dexhale dair, togethe r wit hth e volun e breathed , an db y differenc e t o calculat e th e depositio no f lea di nth e huma nsubject . Th e subject s inhale dambien t ai r b y mout hvi a a non-retur nvalv e (Figs . 4.1 , 4.2) . Throughout , th e nos e remaine dclose dwit ha cli panddepositio no f P bi nth e nos e wa s avoided . Afte r filtration , th e exhale dai r passe dthroug ha ga s mete r t o measur e th e volum e breathed . Th e tubin g of th e apparatu s wa s kep t t o a minimu m t o minimis e th e doubl e swep t volume an dth e depositio nlosse s o f P bt o th e apparatu s itself . Durin g col dweathe r the exhalatio nfilter s wer e enclose di ninsulated , heate dboxe s t o preven t wettin g of th e filte r pape r wit hcondense dwate r vapour . T o minimis e th e pressur e dro pacros s th e exhalatio nfilter s i t wa s necessar y t o us e 1 8 c

m diameter disc s o f Whatma nGF/ A filte r paper s supporte dby nylo ngauz e i nspeciall y constructe d glas s holders . B

y introducin g a pressur e transduce r int o th e system , linke dt o a char t recorder , a recor dof breathin g wa s obtaine dfro m whic hmea ntida l volune , an d th e duratio no f breaths , wer e calculated . . Th e norma l metho do f extractin g P bfro m smal l filte r papers.wa s to boi l the m i n a fe w m l o f concentrate dHNO , i na beaker , o r t o refluxth e paper s i n50 % HNO, . Howeve r th e larg e GF/ A paper s presente dcertai nproblems . Sinc e th e paper s d o no t dissolv e i nHNO, , andar e reduce dt o a pul ponl y by vigorou s boiling , i t wa s impracti ca l t o boi l the

m i na smal l volume of acid . Furthermore , th e reflux"wet-ashing " of suc ha larg e GF/ A

pape r release dabou t 1 2 u g P beve nfro m a blank , unuse dpaper , wherea s onl y

6 ug migh t b e collecte do nth e exhalatio nfilte r pape r durin g a 3-hou r inhalatio no f 1 0 u g m 

### - 3 Consequentl y i t wa s necessar y

t o extrac t the exhale dP b fro m th e pape r withou t extractin g th e intrinsi c P bfro m th e pape r itself . Variou s 20 3 technique s wer e appraise dusin g Pb-labelle dexhaust . Sequentia l leachin g o f th e paper s wit hcol d0.5 % HNO , prove dmos t satisfactor y resultin g i n95 % extractio nof exhaus t Pbfro m th e paper s whils t consistentl y removin g onl y 1 M g o f th e intrinsi c Pb . Thi s extractio nprocedur e wa s validatedwit hstabl e exhaus t P bb

y comparin g measurement s o f P bi nai r usin g bot hsmal l ( 2 cm ) and1 8 a n 20 3 diamete r paper s i nparallel . Previou s wor k wit hP bha dvalidate dthe inhale/exhal e filte r metho dfo r measurin g huma nretentio nof P b(se e Sectio n4. 3 below) , andgive n th e opportunit y

t o measur e P bdepositio nt o th e tubin g an dvalve s o f th e equipmen t Itself . Usin g stabl e lea di nth e field , a signa l o nth e exhalatio nfilte r o f 2 Mg (i.e . 0. 2 M

g ml " fo r AAS ) o r twic e th e unuse dpape r backgroun dvalu e o f 1 M g wa s th e limi t o f sensitivit y o f thi s technique , althoug ha signa l o f a t leas t 3 Mg wa s pre ferred . Thus , i na ninhalatio nexperimen t wit ha duratio no f 41 $ hours , th e maximu

m possibl e withou t undu e discomfor t t o th e subjects , 2. 0 M g •» " wa s th e minimu m feasibl e concentratio no f P bi nai r (50 % retentio nassumed) .

-41 -P.4 3



### 4. 2 Inhalatio n experiments i n th e fiel d A tota l o f

4 6 inhalatio n experiments wa s don e b y 3 subjects . Th

e location s wer e (a ) Motorwa y

- o n th e har dshoulde r o f th e M 4 a t Hesto n(Fig . 4.l) , o r travellin g i n a vehicl e t o an d fr o betwee nJunction s 2 an d 5 (Fig . 4.2) . (b ) Roundabou t - alongsid e th e Hogart hroundabou t a t Chiswick . (c ) Genera l urba n- i n vehicle s travellin g i n th e busies t area s o f Chiswic k an dHammersmith , o n th e Nort han d Sout hCircula r Road s an d i n Reading . (d ) Ca r par k - i n a multi-store y ca r park . Inhalation s wer e no t practicabl e i n suburba no r rura l area s a s a minimu m P b

- 3 concentratio no f 2 p g m wa s needed . Th e breathin g parameter s wer e no t standardised , a s i t wa s impracticabl e t o se t u pspirometer s an d simila r equipmen t o n motorwa y har dshoulder s an

d i n movin g vehicles . Als o i t wa s preferre dtha t subject s breathe dnormally , an d the y usuall y becam e unawar e o f thei r breathin g pattern s afte r a few minutes . th e arrangement s mad e t o minimis e resistanc e t o breathin g i n the apparatu s helpe di n thi s respect . A s i nlaboratory

experiments , th e percentag e depositio ni n th e lung depende do n th e lengt ho f th e respirator y cycl e (Fig . 4.3 ) whic hvarie dbetwee nsubjects . Variation wit htida l volume i s als o t o b e expected . Howeve r analysi s o f varianc e o f th e result s o f Tabl e 4.1 , usin g th e metho dfor unequa l number s i n sub-classe s wit hon e missin g plo t (Kendall , 1945) , she-we d tha t between-subjec t varianc e fel l jus t shor t o f significanc e a t th e 5 % level . Between-locatio nvarianc e wa s significan t a t th e 1 % level . Th e mea ndepositio ni n th e lung o f 6.1% give ni n Tabl e 4. 1 fo r th e motorwa y 20 3 inhalation s i s consisten t wit hlaboratory result s obtaine dwit hPb-labelle dfres h exhaus t aeroso l having IME D o f 0.0 3 u m (Tabl e 3.7 ) (se e Sectio n5 below) . I t wa s no t expecte dtha t percentag e depositio na t th e roundabou t woul db e equall y hig ha s i t ha dbee nanticipate dtha t aggregatio nwoul dhav e reduce dth e proportio no f lea di n th e nucleu s mode . Th e fractio npenetratin g t o the filte r o f th e Anderse nimpacto r a t th e roundabou t wa s les s tha na t an y o f the othe r locations , wher e particl e size s wer e measured . Th e particl e siz e distributio na t th e roundabou t wa s bimodal , wit h30 % o f th e P bhavin g a mea ndiffusiona l diamete r o f 0.0 5 M m an d 42 % bein g betwee n1. 0 an d 4. 2 M m equivalen t diameter . Diffusiona l depositio no f the smal l fractio nwoul dhav e bee nefficien t i n the pulmonar y regio no f th e lun g whils t impactio no f th e large r particle s i n th e tracheobronchia l system ma y hav e contribute dt o th e hig hoveral l deposition . I f thi s wa s so , th e assimilatio no f th e deposite dP bma y hav e bee n differen t a t th e two locations , wit hpossibl y mor e mucociliar y

clearanc e o f th e large r particle s a t the roundabout . I t wa s no t possibl e t o measur e th e uptak e o f the leadt o th e blood , ainc e th e elevatio no f bloo dlea di n an y on e inhalatio nca n b e calculate dt o hav e bee nn o mor e tha na fractio no f 1 M g pe r 100.m l o f blood . Th e mea nvalue s fo r pulmonar y depositio no f th e genera l urba nan d ca r par k lead aerosol s wer e bot h48% . Th e particl e siz e distribution s wer e als o similar , th e

-42 -P.4 4
Anderse nimpactor s givin g a *WE D o f 0. 3 Mm , whic hi s a figur e ofte nquote dfor urba n leadaerosol s i nth e USA . Th e percentag e penetratin g t o th e filte r o f the Andei-Ar n sample r i nth e urba narea s wa s intermediat e betwee ncorrespondin g percentage s fo r the M 4 an droundabou t aerosol s (Tabl e 3.5 ) andth e IWE D o f th e penetratin g fractio n (0.0 8 |*i ) wa s slightl y highe r tha ni neithe r o f th e othe r two cases . Th e urba n aerosol s thu s lacke dth e potentia l fo r ver y effectiv e depositio neithe r b y diffusio n o r impaction . Thi s ma y hav e bee ntru e als o o f th e rura l aerosol , bu t n o lung depositio nmeasurement s coul db e mad e wit hit . Althoug hthe variation s o f percentag e depositio nwit hlocatio ni nthe fiel d experiment s wer e explicabl e i nterm s o f th e particl e siz e analyses , th e result s fo r 203 - the urba nlocation s appeare dt o diffe r frc m expectatio nbase do nth e P bexperiments , particularl y

whe ncompare dwit hth e result s o f Well s e t al . (1977) . I ntha t wor k onl y 15-20 % depositio no f aggregate daerosol s (0. 5 m WVIED) wa s obtaine dcompare dwit h 48 % depositio no f urba nan dca r par k aerosol s (0. 3 u m *WEC ) i nth e field . Th e laboratory

aerosol s wer e i na narro w siz e rang e andlacke dbot hth e smalles t and larges t end s o f th e particl e siz e spectru m foun di nth e field . Nevertheles s the fiel dvalue s wer e highe r tha nexpecte dfro m theor y (Mercer , 1975) . 4. 3 Compariso no f fiel dandlaborator y method s Sinc e differen t sets.p f equipmen t an dmethod s o f analysi s wer e use dfo r th e laboratory

andfiel dinhalation s i t wa s decide dt o d o laborator y experiment s wit ha n aggregate dnon-radioactiv e aeroso l usin g th e fiel dequipment . Th e result s ar e show n i nTabl e 4.2 . Th e observe ddepositio naverage d55 % for subjec t P L an d42 % fo r subjec t MJH . Usin g th e regressio nline s o f percen t depositio nversu s lengt ho f respiratory

cycl e derive db

y Well s e t al . (1977 ) frc m experiment s wit haggregate d 20 3 Pbaerosol , average s o f 22 % and18 % depositio nwoul dhav e bee nexpected . I t appeare dtherefor e tha t th e highe r depositio nfoun dwit hstabl e lea dmeasurement s i n the fiel dapplie dals o whe nstabl e lea danalysi s wa s applie di na laborator y experiment . I na furthe r attemp t t o resolv e the discrepanc y a mor e elaborat e compariso nwa s mad e usin g bot hstabl e an dradioactiv e lea dsimultaneously . Th e origina l laborator y syste m o f cylindrica l exhalatio nfilter s andspiromete r breat hcontro l wa s compare d wit hth e fiel dsyste m comprisin g dis c exhalatio nfilters , pressur e transduce r an d breat hrecorder , an dga s meter . A balloo nwa s adde dt o th e latte r afte r th e ga s meter , s o tha t th e volum e coul db e confirme do nth e standar d"wet " ga s mete r use di n al l laborator y

work . Bot hsubject s P L andMJ H di dtwo inhalation s o f eac htype . Wit hthe laborator y

equipmen t th e tida l volume s wer e 1. 1 an d1. 7 1 a s i npreviou s laborator y

work . Wit hth e fiel dequipmen t th e breathin g pattern s wer e natura l and wer e unobserve db

y th e subject . Intermediat e inhalation s wer e als o don e usin g the laboratory

equipmen t wit hth e spiromete r replace db y th e pressur e transduce r and recorder , andwit hnatura l breathin g pattern s i norde r t o se e whethe r consciou s regulatio no f breathin g wa s a nimportan t factor . Followin g eac hinhalatio nwit hth e fiel dequipmen t radioactiv e countin g wa s don e o nal l the intac t filte r papers , an dals o onth e solution s followin g extractio no f the

-43 -P.4 5



### pape rprio rt o analysi s b y AAS . Th * efficienc y o f

P b recovery fro

m th e larg e exhalatio n dis c filter s wa s 99.2 % w'- h S.D . 0.2ft . Ther e wa s goo d agreemen

tbetwee n th e estimate s o f

percentag e depositio n fro m radioactiv e an

d stabl e P

b analysis , th e rati o o f radioactive:AA S measurement s bein g 1.02% wit h S.D . 0.1 5 (Tabl e 4.3) . I n addition , ri g deposition s wit h th e fiel d equipmen twer e checke d b

y radioactiv e count in g an d al l th e figure s fo rpercentag e retentio n were correcte d fo rri g depositio n an d doubl e swep tvolumes . Estimation s o f th e retentio n o f

radioactiv e P

b wer e als o cross-checke d b

y whol e bod

y counts . Measurement

s o f particl e siz e were mad e usin g Anderse

n impactor s an

d th e result s derive d b

y bot h radioactiv e countin g an d AAS . Th e particl e siz e distribution s o f radioactiv e an

d non-radioactiv e P

b were virtuall y identical . As i n previou s labora tor y inhalation s astabl e aggregate d aeroso l o f ftMED 0. 5 M

m wa s observed . Ther e wa s very goo

d agreementbetween th e radioactiv e an d stabl e P

b analyses , validatin g th e extractio n an d AA S analysi s procedure s followin g fiel d inhalations . Th e tw o set s o f equipmen

tals o produce

d quit e simila rresult s usin g th e sam e aerosol , althoug h th e ratio s o f observed/calculate d value s tende d t o b e highe rfo rth e fiel d equipmen tthan fo rth e laborator y equipment . Whethe rbreathin g pattern s wer e consciou s o rnot , seeme d t o mak e no difference . Bot h methods produce

d value s fo r percentag e retentio n somewha thighe rthan th e value s obtaine d b y Well s e tal . (1977 ) an d i n bette ragreemen

twit h th e dat

afro m Chamberlai

n e tal . (1975) . Th

e reason s fo rth e "discrepancie s between th e thre e set s o f dataremai

n unresolved .P.4 6

TABL E 4. 1 Depositio ni nlun

g o f environmenta l lead (a ) tida l volume , litres ; (b ) lengt ho f respirator y cycle , second s pe r breath ; (c ) percentag e deposition .
Subjec t

A • "L. » W •

, t 1

Mea n & SE

M * J •!! •

1


### 1

, Mea n & S E

; P.L .



# 1 i \ Motorwa y ( a ) (b ) (c ) 1. 5 6. 0 7 4 . 1. 2 6. 4 8 5

- - 7 1 0. 6 5. 1 5 8

7 2 1 6

1. 4 4. 7 6 3 1. 1 4. 6 5 2 0. 6 4. 3 7 0 0. 6 5. 2 6 8 1. 0 7. 1 5 7 0. 7 5. 5 3 0 0 . 8 5. 1 4 8 0. 7 5. 0 6 2 0. 6 4. 9 5 3

5 6 1 4

- - 7 7 0 . 8 5. 9 6 8 0. 6 4. 2 4 2 0. 7 4. 3 5 5 0 . 5 4. 2 6 7 j 0. 6 4. 2 6 3 1 Roundabou t (a ) (b ) (c )

- - 8 0

- 5 7 0 . 8 6. 3 6 5

6 7 i 7

- 6 2

6 2

0 . 9 5. 8 6 7 0 . 9 5. 2 6 2

- 5 5 Genera l Urba n

(a ) (b ) (c )

- - 5 9 1. 0 6. 0 5 5 0 . 8 5. 6 3 1 0 . 7 5. 5 4 6

- 2 6 0 . 7 5. 3 4 5 0. 6 4. 5 4 1

4 3 i 5

0 . 6 5. 1 2 8

•

2 8

1. 2 6. 9 7 0

- - 6 8

- - 4 7

- 5 1 0 . 8 4. 9 4 0

- - 5 8 0. 6 4. 0 4 2 Ca rpar k (a ) (b ) (c )



# ' i

0 . 7 5. 4 4 7 0. 7 6. 0 3 7 0 . 7 5. 0 4 2

1 |

4 2 r3

0. 6 4. 2 6 6 0 . 5 4. 1 4 6 0. 6 4. 4 5 1

Mea n & S E
A l l subject s 6 2 i 5
6 1 * 3 6 1 ±3 ; I 

# 1 6 4 1 j j 5 4 1 5 :
4 8 1 4 5 4 : 6
4 8 * : 4

-45 -''""•*• " '•"-•TTTT "

TABLE 4. 2 Depositio ni nlun

g o f stabl e aggregate d exhaus t Pbusin g fiel d equipmen t

Subjec t

P.L . 1 2 3 4 5

M * J ali a 1 2 Tidfaj volum e (litres )

0.8 5 0.8 4 0.9 6 1.0 7 1.0 1

0.7 6 0.7 5 Second s

pe r breat h

6. 1 6. 1 5. 2 5. 5 5. 4

5. 6 5. 7 % deposition

Observe d

56. 2 59. 1 48. 1 54. 4 53. 9

41. 2 42. 4 Calculated *

22. 3 22. 3 21. 0 21. 8 21. 5

17. 9 18. 1 observe d

calculate d

2.6 1 2.6 5 2.2 9 2.5 0 2.5 1

2.3 0 2.3 4

* Derive d fro

m Well s e t al . (1977 ) wit ha facto r 1. 1 t o correc t fo r MJ H fro

m tida l volume o f 1. 0 1 t o 0.7 6 1 .

TABL E 4. 3 Percentag e depositio n b y radioactiv e and stabl e lead analysi s

Sub jec t

MJ H

PL Ru

n

I I I II I I V V

I I I II I I V V Apparatu s
Cyl . spiro . Cyl . spir o Cyl . recorde r Disc.recorde r Disc.recorde r Mea n & S E

Disc.recorde r Cyl . spiro . Cyl . spiro . Cyl.recorde r Disc.recorde r Mea n & S E Tida l

volum e 1 . 1.1 4 1.7 7 1.1 0 0.7 5 0.8 0 1.1 1

0.7 6 1.1 4 1.7 7 0.8 9 0.7 5 1.0 6

1 See s

pe r breat h
7. 8 9. 9 5. 9 5. 9 6. 3 7. 2

5. 2 8. 9 10. 1 5.4 7 5.4 7 7. 0 % Deposition Pb 2 0 3
32. 3 43. 8 41. 0 30. 1 30. 8 35. 6 t 2. 8

29. 6 45. 5 55. 2 32. 1 41. 7 40. 8 t 4. 6 Stabl e

P b

-

-

- 24. 2 32. 9 28. 6

32. 1

42. 9 37. 5 Calcu late d 28. 4 37. 5 21. 9 18. 5 18. 8

17, 5 34. 8 45. 6 24. 4 24. 5 Observe d

Calculate d

1.1 4 1.1 7 1.8 7 1.4 7 1.6 9

1.7 6 1.3 1 1.2 1 1.3 2 1.7 3 

# i

-46 -vm-fjyw- p-= . iryifff

. •

-

AER E - R 919 8 Fig . 4. 1 Subjects inhalin g exhaus t aeroso l o n th e hardshoulde r of th e M 4

4 7c CM » 

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### r r o ~ M O 

### a . • o 8 0

7 0

6 0

5 0
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3 0

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o Motorway s

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i 

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# o °
° ° o •

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1 0- 5 1 0 1 5 6 0 

### 6 5 7 0 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 Lengt h of respirator y cycl e Is.breath"' ) A ERE . R9198 . FIG . 4.3 . DEPOSITIO N OFLEA D I N LUN G I N FIEL D EXPERIMENT S VERSU S LENGT H O F RESPIRATOR Y CYCLE .

. o

### 5 . "Inhalation o f radioactiv e lea d aerosol s 5. 1 Objec to f

experiments
a Th e radioactiv e labellin g o f exhaus t aerosol s wa s don e t o enabl e th e depositio n i nth e lung , transfe r t o othe r organs , an d excretio no f leadt o b e followe dby detectio no f th e radioactiv e label . I nthi s way , th e fat e i n th e bod y o f lea d inhale ddurin g a shor t perio do f exposur e coul db e determine dwithou t interferenc e fro m th e backgroun do f stabl e lea dalread y presen t i n tissues . Previou s .wor k (Chamberlai ne t al . 1975 , Well s e t al . 1977 ) ha d give nconsiderabl e informatio no n th e percentag e depositio ni n th e lung an d it s dependenc e o n tida l volum e an d lengt h o f respirator y

cycle . I n th e presen t work , particula r attentio nwa s give nt o fres h non-aggregate dexhaus t aerosol , sinc e wor k i n th e environmen t (Sectio n3 above ) ha d show ntha t thi s wa s th e for m o f th e ambien t aeroso l particularl y nea r motorways . Wor k wit haggregate dexhaus t aerosols , an d wit hleadoxid e an d nitrat e aerosols , ha d th e mai nobjec t o f looking fo r possibl e effect s o f chemica l compositio no f th e particle s o n th e rat e o f clearanc e fro m th e lung , bu t th e opportunit y wa s als o take n t o measur e percentag e deposition . Th e inhalatio npatter ni n thes e experiment s wa s chose nt o maximis e depositio ni n a relativel y shor t inhalatio nwithou t usin g unnatura l breathin g patterns . , 5. 2 Preparatio nand inhalatio no f labelle daerosol s

20 3 Th e isotop e P bi s produce db y bombardin g thalliu

m wit hproton s i n th e cyclo tro na t th e Medica l Researc hCounci l Uni t a t Hamnersmit hHospital . Th e radioactiv e half-life i s 5 2 han d deca y i s b y electro ncapture . Th e associate d27 9 ke V gamm a ra y i s detecte db

y th e photoelectri c effec t i n garren a spectrometers . Th e method s o f measvremen t hav e previousl y bee ndescribe d(Chamberlai ne t al . 1975) .

21 2 Anothe r radioactiv e isotop e o f lead , Pb , wit ha radioactiv e half-liT e o f onl y 10. 6 hha s als o bee nuse dt o stud y depositio ni n th e lun g an d uptak e t o bloo d 21 0 (Booke r e t al . 1969 , Hurs hand Mercer , 1970) . Th e long-live disotop e Pb , half lif e 2 2 years , ha s bee nuse dfo r anima l studies . 20 3 Th e relativel y

shor t half-lif e o f Pb , an d th e mdd e o f it s decay b y electro n capture , limi t th e radiologica l dos e t o th e subject . Als o equipmen t an d subject s ar e fre e o f radioactivit y an d availabl e fo r furthe r experiment s i n a comparativel y shor t period , sinc e th e radioactiv e decay reduce s th e activit y by a facto r o f 10 0 i n 1 4 days . Thi s als o mean s tha t th e uptak e and excretio no f an y on e dos e ca n onl y

b e followe dfo r a simila r period . I n extrapolatin g th e result s o f experiment s t o th e cas e o f chroni c exposure , certai nassumption s hav e t o b e made , whic hca n b e verifie d onl y by referenc e t o long ter m studie s b

y othe r methods , reviewe di n Sectio n1 0 o f thi s report . 

### T o obtai n labelle d motorexhaust , tetr aethy l lea d (TEL ) wa s synthesise d fro

m th e radioactiv e PbCl 2 

### b y aGrignar

d reactio n an

d adde d t o lead-fre e petro l togethe r wit h a n appropriat e amoun

to f ethylen e dibromid e scavenger . Th e concentratio n o f TE L i n th e petro l wa

s equivalen tt o 0. 5 g Pb/1 . A single-cylinder , hig h compression , 4-strok e Hond

aengin e wa

s couple d t o agenerato rt o provid e aload . Th e engin e wa

s

-50 -P.5 2

wermed-u

p o n ordinary leade d petro l an d the n switche d t o th e labelle d petrol , whic h wa s consuned i n a fe

w minutes . Ther

e wa s S% o f C O i n th e exhaus tgas , an d thi s ha

d t o b e reduce d befor e i twa s inhaled . Thi s wa s don e i n tw o differen tways , whic h als o gav e differen tlea d concentration s an d particl e size . (a ) Wind-tunnel aerosol s Th e exhaus twa

s passe d int o a wind-tunne l operate d i n th e single-pas s mod e wit h a n airflo w o f

2. 5 m/ s (Fig . 5.1) . Th

e 0 0 i n th e tunne l wa s les s than 100 0 ppm , which wa

s low enoug

h fo rinhalation s lastin g a fe w minutes . Th

e lea d concentratio n wa

s usuall y abou t4 0 n g it " , an

d i n a typica l experimen tabcw t0. 4 203 M g o f lead , wit h 10

0 nanocurie s (nCi ) o f P b activity , wa

s deposite d i n th e lung . Th e particl e siz e o f th e wind-tunne l aeroso l wa s measure db y simila r method s t o thos e use dfo r th e motorwa y aerosol . Th e diffusio nbatter y wa s use dt o measur e th e diffusio nmea nequivalen t diamete r (CMED) . Th e fractiona l penetra 20 3 tio nthroug hth e batter y wa s obtaine dfro

m th e rati o o f P bactivit y i n th e upstrea m an ddownstrea

m air , wherea s i n th e environmen t th e stabl e P bwa s measured . Anderse nimpactor s wer e als o used , but , i n th e wind-tunnel , al l th e particle s penetrate dt o th e filter , implyin g non e greate r tha n0. 3 u m diameter . Th e aerosol s wer e als o sample db y therma l precipitator s fo r electro nmicroscopy (Fig . 5.2) ; an

d th e volun e mea ndiamete r (VMD ) deduce dfro m th e micrograph s agree dwel l wit hth e CME D fro m th e diffusio nbatter y (Tabl e 5.1) . Whe nth e exhaus t wa s injecte dint o th e tunne l immediatel y downstrea

m o f th e impelle r fan , a n aeroso l wit hCME D o f 0.0 4 u m wa s obtained , a s i n th e earlie r wor k o f Chamberlai ne t al . (1975) . Smalle r particles , wit hCME D equa l t o 0.0 2 M m wer e obtaine db

y mor e rapi dinitia l dilution . Th e je t fro m a centri fuga l blowe r (win

dspee d4 0 m

s " ) wa s mixe dwit hth e exhaus t andth e mixtur e passe ddow

na tub e 1 0 a ndiamete r x12 0 cm lon g int o th e tunne l operatin g a s before . Th e aeroso l forme dwa s slightl y smalle r tha nany

foun di n th e field . A large r siz e (CME D = 0.0 9 Mm ) wa s obtaine db y introducin g a 2 0 1 delay vesse l betwee nth e exhaus t pip e an dth e wind-tunne l (Fig . 5.1) . Betwee nthem , th e 0.02 , 0.0 4 and0.0 9 H naerosol s covere dth e "nucleu s mode " o f particl e size . Subject s inhale db

y mout hthroug ha non-retur nvalve , exhalin g vi a a glas s fibr e filte r t o a balloo n(Fig . 5.1) . Th e syste m wa s a s use di n th e fiel d excep t tha t th e balloon s replace dth e dr y ga s meter s use dfo r volume measuremen t i nth e field . Thes e ga s meter s wer e calibrate dagains t th e standar dwe t ga s mete r whic hwa s use di n al l laborator y work . I n al l case s th e breathin g wa s recorde db

y pressur e transduce r an dchar t recorder . 20 3 Th e inhale dconcentratio no f P bwa s measure db y concurren t samplin g fro m th e wind-tunne l an dthe equipmen t lines . Th e volume s o f th e part s o f th e equipmen t wer e minimise dan dcorrection s wer e mad e fo r double-swep t volume s whe n 20 3 calculatin g retention . Depositio no f P bi n th e ri g wa s measure db y gamm a countin g andappropriat e correction s made . Th e losse s wer e mainl y b y diffusio n an dwer e mos t importan t for th e smalles t particl e sizes .
-51 -P.5 3

Fo r prope r operatio no f th e non-retur nvalves , i t WB S foundnecessar y t o operat e the tunne l a t a sligh t negativ e pressur e (abou t 1 c m HjO) , whic hwe e don e b y us e o f a

- extrac t fan a t it s outlet . Thl a als o prevente dexternn l

20 3 contaminatio no f th e subjec t b y P bleakin g fro

m the tunne l (b ) Boxaerosol s Th e 60 0 1 bo xpreviousl y use dfo r storin g th e aeroso l (Chamberlai ne t al . 1975 ) wa s als o use di n th e curren t work , bot hwit hexhaus t aeroso l and wit h aerosol s mad e b

y burnin g TE L i n propane . By th e additio no r eliminatio no f nitroge nfro

m th e flame , lea dnitrat e an d oxid e aerosol s wer e obtained . Con centration s o f C O and CO , i n exhaus t aeroso l wer e reduce db y reactio nwit ha n oxidativ e catalys t (Hopcalite ) an d mois t NaO H pellet s o n the floo r o f th e box . C O wa s reduce dt o 100 0 pp m i n abou t on e hour . Meanwhil e th e particle s coagulate dand forme dchai naggregate s (Well s e t al . 1977 , Fig . id) . I n some experiment s th e aeroso l wa s expose dt o sunligh t fo r severa l hour s befor e inhalation s too k place . I n san e other s b y varyin g th e runnin g condition s o f th e engin e (riy

hmivt^re . n o load ) a carbonaceou s aeroso l wa s produce d (Well s e t al . 1977 , Fig . la) . 203 E Th e confinemen to f

th e aerosol s i n th e bo x enable d highe rconcentration s o f

- 3 P b t o b e obtaine d tha n i n th e wind-tunnel . Typically , 1 t o 2 MC i wer e deposite d i n th e lun g i n eac h experiment . Thi s wa s th e minimu m activit y require d t o enabl e th e concentration s i n bloo d an d excret at o b e followe d fo r 1 4 days . Th

e concentratio n o f

stabl e lea d was highe ri n th e box tha n i n th e wind-tunnel , an d varie d considerabl y betwee n experiments . The minimu m leve l wa s se tb

y th e nee d t o us e a tleas t5 0 m g P b carrie ri n th e synthesi s o f th e labelle d TEL. Th

e concentratio n o f

P b i n th e box varie d from 400 0 t o 20 0 M g m bu teac h inhalatio n laste d afe w minute s only . I n th e whol e serie s o f wind tunne l and bo x experiments , th e amounto f P b deposite d i n th e lun g varie d b y thre e order s o f

magn i tude , fro

m 0. 3 t o 45 0 Mg

, bu tn o associate d effect s o n rat e o f clearanc e o ruptak e t o bloo d wer e foun d (Sectio n 6.10) . Eve n a tth e uppe r limit , th e amoun

to f lea d enterin g th e bloo d from th e lun g i n on e experimen twa s considerabl y les s tha n th e amoun t(typicall y abou t1 mg ) normall y circulating . The particl e size s o f th e bo x aeroso l wer e measure d b y us e o f th e Anderse n impacto r(Tabl e 5.2) . Th e MUE D wa s i n th e rang e 0.3 5 t o 0.7 0 u m fo rth e exhaus taerosol s an d 0.4 0 t o 0.8 0 u m fo rth e oxid e and nitrat e aerosols . Th e method s o f

inhalin g from th e box and measurin g th e depositio n i n th e lun g wer e a s describe d b y Well s e tal . (1977) . 5. 3 Depositio n o f

labelle d aerosol s i n th e lun g 5.3. 1 Wind-tunne l aerosol s Tabl e 5. 3 show s th e measurement s o f lun g depositio n o f

th e wind-tunne l aerosol . Eigh tsubject s too k par ti n thes e experiments , bu ti twa s no tpossibl e t o perfor m sufficien treplicat e experiment s t o distinguis h between-subjec tvaria tio n from th e othe rvariables . Experiment s wer e don e wit h thre e particl e

-52 -P.5 4

size s (0.02 , 0.0 4 and0.0 9 M » CMED) . Breathin g parameter s wer e tida l volum e (litres/breath ) andlengt ho f the respiratory cycl e (seconds/breath) . Thes e wer e varie dconsiderabl y i nth e experiment s wit h0.0 2 M m particles , bu t les s s o fo r th e othe r particl e sizes . A s i npreviou s experiment s (Chamberlai ne t al . 1975) , th e percentag e o f th e inhale daeroso l whic hwa s deposite di nth e lun g wa s measure db y two method s 20 3 (a ) comparin g th e activit y o f P bo na nexhalatio nfilte r wit hth e activit y inhaled , a s deduce dfro m th e volume inhale dan dth e activit y

pe r uni t volum e o f air , 20 3 (b ) assessin g th e P bdeposite di nth e lun g b y externa l gamma ra y

spectrometr y an dcomparin g thi s wit hth e activit y inhaled . A s show ni nTabl e 5.3 , ther e wa s goo dagreemen t betwee nth e two method s o f estimatin g depositio ni nth e lung . Th e percentag e depositio ncorrecte dfor dea dvolvme a s show

ni nTabl e 5.3 , i s plotte dagains t th e lengt ho f th e breathin g cycl e i nFig . 5.3 . Percentag e depositio nincrease dwit hdecreasin g particl e siz e andwit hincrease dlengt ho f respiratory cycle , a s expecte dfo r sub-micro n particle s deposite di nth e lun g mainl y b y Brownia ndiffusion . Fo r the 'Standard Man ' respirator y cycl e o f 4 s (1 5 breaths/min) . depositio n varie dfro

m 249 ? fo r th e 0.0 9 u m aeroso l t o 685 ? fo r th e 0.0 2 Mm aerosol . I nth e motor wa y inhalatio nexperiment s (Tabl e 4.1) , the respirator y cycl e average d5. 3 s , an dthe leadaeroso l hada DME D o f abou t 0.03 5 \im (Tabl e 3.7) . Interpolatin g betwee nthe 0.0 2 an d0.0 4 u m

curve s i nFig . 5.3 , abou t 56 $ depositio ni nthe lung woul db e expected , compare dwit hth e averag e o f 61" ? foun di nth e fiel dwor k (Tabl e 4.1) . 5.3. 2 Bo xaerosol s Aerosol s o f 'clean ' exhaust , carbonaceou s exhaust , 'clean ' exhaus t expose d t o sunlight , lea dnitrat e an dleadoxid e wer e inhale dwit hth e mai nobjec t o f testin g effec t o f chemica l stat e o nlun g clearance . Subject s too k lon g dee p breath s (mea nandS.D . o f respirator y cycl e 9. 3 i 3. 1 s , tida l volun e 1. 8 ±0. 5 1 ) t o maximis e deposition . Th e percentag e depositio ni s show ni nTabl e 5. 4 an d Fig . 5.4 . Th e exhaus t aerosol s wer e deposite dmor e effectivel y tha nth e oxid e or nitrat e aerosol s althoug hthe particl e size s o f th e latte r wer e greater . Th e result s wer e normalise dt o a tida l volume (V_ ) o f 1 1 b y applyin g factor s derive db

y Well s e t al . (1977) . I nFig . 5. 5 th e curve s showin g th e mea n relatio nbetwee npercentag e depositio nan dlengt ho f th e respirator y cycle , wit h andwithou t th e normalisin g factor , ar e compare dwit hsimilarl y treate ddat a fro

m th e earlie r Inhalatio nserie s o f 197 4 (Chamberlai ne t al . 1975 ) an d197 5 (Well s e t al . 1977) . Th e 197 5 results , fo r unknow nreasons , giv e lowe r depositio nfo r shor t breathin g cycle s anda les s stee pris e wit hincrease dlengt ho f cycle . Th e sam e equipmen t an dtechnique s wer e use dfo r bot hserie s andth e aeroso l characteristic s wer e simila r a s determine db y bot helectro nmicroscopy an d Anderse nimpactio nsamplin g (Tabl e 5.2) .

-53 -Th e fiel dinhalatio nexperiment s i nth e 'genera l urban ' an d 'ca r park '

area s gav e a mea nstabl e lea ddepositio no f 46% fo r a mea nrespirator y cycl e o f 5. 5 s . Thi s i s a highe r depositio ntha nwa s foun dI nan y o f th e bo xaeroso l series , bu t a s previousl y pointe dout , the ambien t aeroso l ha d a wide r particl e siz e spectru

m tha nth e bo xaerosol . 5.3. 3 Compariso nwit hothe r publishe dwor k Th e variatio no f percentag e depositio ni n th e lun g wit hparticl e siz e accordin g t o severa l investigator s i s show ni n Fig . 5.6 . Fro m th e presen t work , th e result s fo r 0.02 , 0.0 4 and 0.0 9 M m particle s wer e take nfro m Fig . 5. 3 wit h 4 6 breathin g cycl e (1 5 breaths/min ) whic hi s th e standar dICR P figur e fo r rest in g adul t males . Th e mea no f the result s o f th e thre e serie s i n Fig . 5. 5 ha s bee nuse dt o deriv e a poin t fo r 0. 5 M m kMED . Th e compute dcurv e o f Jame s (1978 ) 20 3 agree s wel l wit hth e Pbresults . Earlie r calculation s b y th e Tas k Grou pon Lun g Dynamic s (1966) , no t show ni n Fig . 5.6 , gav e highe r percentag e retentio n fo r ver y smal l particles . Th e experimenta l result s o f Heyde r e t al . (1975 ) an d Mitchel l (1977) , and th e calculate dcurv e o f Y u an d Taulbe e (1977) , al l referrin g t o a tida l volume o f 1 1 , show considerabl e variatio ni n percentag e depositio n fo r particle s o f abou t 0. 5 u m VMED. Thi s i s als o th e siz e fo r whic hth e P b result s ar e mos t variabl e (Fig . 5.5) . 

### 5.3. 4 Variatio n betwee n individual s I nth e analysi s o f results , possibl e systemati c difference s i n efficienc y o f depositio nbetwee nindividua l subject s hav e no t bee ntake nint o account . I n the analysi s o f varianc e o f th e depositio no f stabl e lea d(Tabl e 4.1) , between subjec t varianc e fel l jus t shor t o f significanc e a t th e 55 6 level . Fo r two subject s wh o too k par t i n severa l serie s o f experiments , the rela tiv e percentag e depositio ni s summarise d i n Tabl e 5.5 . Th e result s hav e no t bee nnormalise dfo r tida l volume o r lengt ho f respirator y cycle , bu t thes e wer e comparabl e i n mos t cases .

-54 -P.5 6
- " * •>- 1
—'TT-Tl t

TABL E 5. 1 Particl e siz e o f

wind-tunne l P

b exhaus taerosol s

Serie s

197 5

197 7

I I
197 7

• i

I I . Metho d

Direc tinjectio n wit h loa d
Pre-dilutio n n o loa d
i tI I
Pre-dela y wit h loa d
i t t i
i i i t Particl e siz e (Mm ) Fro m electro n micrograph s VM D M m

0.03 5

0.01 8 0.02 2

0.08 5 0.11 2 0.09 2 O

g

1. 5

1. 5 1. 5

1. 6 1. 5 1. 4 Diffusio n batter y

IME D M m

0.03 9
) ) 0.01 9 !

0.08 0

0.09 0

-55 -TABL E S. 2 Aggregate d aero«ol s Anderse n Impacto rData 

### i l l 20 3 Pb-labelle d exhaus taerosol s (197S-IP77 )

Stag e

0 1 2 3 4 S 6 7 8 (filter ) Ag e a t samplin g <»in ) SO *

cut-of f diam .

U. S 9. 5 5. 7 4. 2 2. 2 1. 0 O. S 0. 3 Percentag e deposite d pe r atag e

Clea n exhaus t U A expose d 7/7/7 6 0. 1 0. 0 0. 1 0. 1 0. 1 46. 3 45. 4 S. B 2. 1
35 0 Clea n

exhaus t 23/3/7 7 0. 1 0. 2 0. 2 0. 4 1. 3 4. 2 25. 3 62. 5 5. 7
11 2 Carbonaceou s

exhaus t 20/4/7 7 0. 2 0. 1 0. 1 0. 3 0. 8 0. 8 24. 1 64. 3 4. 2
11 0 Carbonaceou a

exhaus t IB/5/7 7 0. 1 0. 2 0. 3 0. 3 0. 6 4. 8 20. 5 59. 3 13. 7
11 0

203 , (2 ) Pb-labelle d lead compound s (1976-1977 )

' Stag e

0 1 2 3 4 5 6 7 8 (filter ) Ag e a t samplin g (atin ) Nitrat e

18/8/7 6

0. 1 0. 2 0. 1 0. 2 O. S 36. 1 38. 9 8. 6 15. 1
7 6 Percentag e deposite d p e Nitrat e 7/9/7 6 ( i ) 0. 4 0. 4 0. 3 0. 3 0. 3 0. 6 4. 3 35. 5 58. 0
3 0 (ii )

0. 2 0. 2 0. 2 0. 3 0. 5 56. 3 39. 4 2. 5 0. 5
25 0 Oxid e

10/11/76 .

0. 1 0. 2 0. 2 0. 2 0. 3 10. 7 43. 1 39. 2 6. 3
7 2 r stag e

Oxid e 25/11/7 6

0. 2 O. I 0. 2 0. 2 0. 3 5. 4 37. 5 44. 2 12. 0
6 6 Oxid e

30/11/7 6

0. 1 0. 2 0. 5 0. 2 0. 7 10. 4 59. 6 22. 9 5. 6
9 4
(3 ) 203 ,

Pb-labelle d exhaus taerosol s (1975 ) (Well s e tal . 1977 )
Stag e
0 1 2 3 4 5 6 7 8 (filter ) 'Ag e a t samplin g (atin ) Percentag e deposite d pe r stag e 2/I0/7 S 0.0 4 0.0 4 0.0 4 0. 1 0. 3 10. 1 63. 1 24. 6 1. 7 16 4 3/10/7 5 0.0 7 0.0 4 O.O S 0. 1 0. 3 5. 4 82. 8 10. 8 0. 5

•• 3

-56 -P.5 8

TABL E 5. 3 Depositio n i n lun g o f wind-tunne l aerosol s

Particl e diamete r ur n (CMED )
0.0 2

0.0 4

0.0 9 Subjec t

O N D N MJ H MJ H ACKAC K AC C ACC ACC AO C AC W AC W MJ H MJ H 

### ACC D N RF H DHF A KE B ACC MJ H MJ H DHF A KF B RF H PL AC W P L MJ H Resp .

cycl e s 3. 7 11. 3 6. 6 11. 7 4. 2 20. 9 3. 6 7; 6 3. 6 2. 4 5. 5 0. 8 8. 4 7. 5 3. 8 4. 1 7. 2 6. 6 6. 6 4. 2 9. 0 5. 7 6. 1 7. 0 6. 3 5. 2 7. 4 4. 5 5. 6 Tida l volum e 1
0.6 3 1.2 5 1.1 7 1.4 5 1.4 3 2.1 1 0.3 1 0.3 9 0.3 6 0.3 4 1.1 7 0.4 3 2.0 7 1.2 5 0.7 6 0.8 4 1.1 5 1.3 1 1.0 7

-

- 0.7 9 0.8 5 0.9 7 1.1 0 0.7 2 0.8 8 0.7 0 0.7 8 % Deposition

Filter *
66. 2 80. 0 61. 2 84. 6 82. 3 91. 6 65. 5 72. 7 46. 5 45. 5 79. 9

- 63. 0 51. 7 32. 9 44. 0 58.5^ ' 57, 0 56. 1 45. 1 60. 0 25. 2 35. 6 35. 1 Whol e bod y counte r 67. 0 80. 5 79. 7 85. 5 64. 1 91. 7

- 80. 7 52. 3 52. 3 76. 0 38. 4 56. 9 46. 9 37. 4 \ 44. 6 '?•'56.3 - 52. 9 57. 5 44. 6 58. 8 20. 8 35. 5 | 34. 9 \ 41. 4 |>

? -*- " 45. 6 / 37. 8 | 39. 9 / 24. 8 27.8 ' 34. 4 34. 4 25. 3 21. 9 Mea n% deposition* *
70. 4 83. 0 83. 4

. . 87. 6 85. 8 92. 9 70. 4 86. 2 51. 1 53. 0 80. 7 39. 6 60. 8 50. 2 36. 1 45. 6 58. 9 56. 0 58. 4 46. 6 61. 2 23. 3 36. 3 35. 7 44. 4 39. 9 26. 7 35. 3 24. 0

* Compariso n o f

P b i n inhale d and exhale d air . Correcte d fo rth e effec to f dea d volian e i n apparatus .

-57 -TABL E 5. 4 203 , Depositio n i n lun g o f aggregate d exhaus tand othe rPb-labelle d aerosol s

Dat e

7/7/7 6

18/8/7 6 7/9/7 6

10/11/7 6

25/11/7 6

30/11/7 6

23/3/7 7 20/4/7 7

i 18/5/7 7 1 i Typ e o f aeroso l

Clea n exhaus t expose d t o sunligh t
Lea d nitrat e Lea d nitrat e

Lea d oxid e

Lea d oxid e

Lea d oxid e
Clea n exhaus t Carbonaceou s exhaus t Carbonaceou s exhaus t Subjec t

MJ H DHF A KF B MJ H DHF A RF H AC C MJ H RF H AD C DHF A D N KF B MJ H MJ H AC C D N RF H % depositio n i n lun g

Filte r
4 8 5 5 3 4 2 6 2 6 4 5 6 2 3 1 4 1 3 0 1 4 4 2 ' 3 1 3 9 3 6 3 6 1 ! 4 0 ; 4 3 Whol e

Bod y Counte r 5 1 4 4 2 8 2 6 1 4 3 9 5 3 2 8 4 1 2 6 1 9 4 3 3 0 3 3 3 6 3 8 4 1 4 1 Mea n

49. 5 49. 5 31. 0 ;2 6 2 0 V§ 2 57. 5 29. 5 14 1 2 8 16. 5 42. 5 30. 5 3 6 3 6 3 6 41. 5 4 2 Tida l

volum e 1
2.0 3 1.9 0 1.6 9 1.8 9 1.7 6 1.8 5 1.7 3 1.7 6 1.7 3 1.6 1 1.7 3 1.7 3 1.6 9 2.2 8 1.8 0 1.7 4 1.7 6 1.7 6 Breathin g

cycl e s
9 . 3 7. 4 5. 8 9 . 3 7. 7 8 . 3 10. 0 14. 6 14. 5 7 . 0 5 . 9 17. 6 12. 6 9 . 5 8 . 5 6. 6 7. 4 5. 7

TABL E 5. 5 Variatio n o f

depositio n i n lun g betwee n tw o subject s Typ e o f aeroso l
Laborator y - wind-tunne l Laborator y - aggregate d Fiel d - ope n roa d Fiel d - genera l urba n Fiel d - multi-store y ca rpar k Depositio n rati o PL/MJ H 1.4 6 1.2 0 1.1 6 1.5 0 1.2 9 Nunbe ro f

observation s 1 7 4 1 3 

## i Mea n o f

individua l observation s 1.2 5 • 0.1 3 S.D .

-58 -c c 3 +m •o « - c lri* J

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, . . f .., , . •.?••• •••*•..' •i f

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# • v . .'• * -v r- .•••• . • v.•--. . ;• • •

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## , I — J v•

•i . » / " •W V
(a) (b ) <c ) AER E - R 919 8 Fig . 5. 2 Win d tunne l exhaus t aerosol s use d i n inhalatio n experiment s (a ) 0.0 2 p m DMED , (b ) 0.0 4 p m DMED . (c ) 0.0 9 p m DME D' "-"•" TV'" ' *V

## 2 4 6 8 1 0 1 2

Breathin g cycl e (seconds ) AERE . R 9198 . FIG . 5.3 . DEPOSITIO N I N LUN G O F WIN D TUNNE L AEROSOLS .

-61 -- •*T" T T "T'l'f f * • •ITTI* " "



## , x

## Expose d t

o sunt.gh t E^ou^* ^ [* ^onaceous *

f A Lea d oxid e Pb

O l a

## Lea d nitrat e P

b (N0 3 

## ) 2



### 6 8 1 0 wreathin g cycl e (seconds ) B i AERE . R919 8 FI G SA . DEPOSITIO N I N LUN G O F *0 3 

### P b LABELLE D AGGREGATE D AEROSOL S 1976-197 7 PERCENTAG E DEPOSITIO N v . BREATHIN G CYCL E

-62 -

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o l/ l 

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# 1 1 1 1 1 6 6 1 0 1 2 U 

## Breathin g cycl e (seconds ) 1 6
AER E R9198 . FIG . 5.5 . DEPOSITIO N I N LUN G O F AGGREGATE D AEROSOLS . COMPARISO N O F MEA N DEPOSITIO N CURVES .

-63 -

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3

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## 1

dat a I V T 

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## = 100 0 cm 3 

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### 1 1 197 8 (V T 

### =1000cm 3 

### ) Calculate d 197 8 (V T 

### =500cm 3 

### ) Calculate d 197 7 (VjslOOOcm 3 

### ) Calculate d

Breathin g cycl e 4 second s TM


# \ ^ ^ 0

^

: 

### ^--~^ > " \ - 

# ..j^>* . c£). ^

^^^"" ^ - 

# i i 0 0 1 DME D 0 1 fim MME D 1 0 A.E.R.E . R9198 . FIG.5.6 . A COMPARISO N O F PUBLISHE D DAT A O N TH E DEPOSITIO N I N TH E LUN G O F SUBMICRO N PARTICLES .



# - r/ r<, 

### 7V- , 

### ' •'" /

6 . Clearanc e o f labelle daerosol s fro m th e lun g 6. 1 Objec t o f experiment s Previou s wor k (Booke r e t al . 1969 , Chamberlai ne t al . 1975 ) ha dshow ntha t radio activ e leaddeposite da s particulate s i nth e pulmonar y regio no f th e lun g i s remove d almos t completel y

i na few

days . Mos t o f the lea dpasse s throug hth e lun g membrane s an di s redistribute di nth e circulation . Onl y amal l amount s ar e brough t u pb y ciliar y actio nandswallowe do r transferre dt o lymp hnodes . Muc ho f th e leadi n fres hexhaus t i s presen t a s halide s an di s quit e solubl e i nwater . Ther e remaine d th e question , whethe r lung clearanc e woul db e differen t i f leadaerosol s o f othe r chemica l forms wer e inhaled . 6. 2 Method s o f measurin g rat e o f clearanc e 20 3 Chamberlai ne t al . (1975 ) gav e a metho do f estimatin g th e proportio no f Pb deposite di nth e lun g whic hwa s stil l ther e a t variou s time s afte r inhalation . A pai r o f colllmate dsodiu m iodid e crystals , on e abov e an dth e othe r below

th e ches t o f 20 3 a supin e subject , responde dt o the gamm a ray s fro

m P bi nth e lung s an dsurroundin g t yc\\ tissues . Th e contributio nfro m P bi nth e ches t bu t no t i nth e lun g wa s estimate d fro m th e respons e o f similarl y place dcounter s i nseparat e experiment s i nwhic hP b wa s injecte dintravenously . Afte r bot hinhalatio nandinjection , measurement s wer e 20 3 als o mad e o f systemi c P bi nth e leg s andals o venou s bloo dsample s wer e analysed . 20 3 Thu s th e contributio nt o th e respons e o f th e ches t counter s t o systemi c P bwhic h 20 3 ha dentere dth e bloo dstrea m fro m th e lun g coul db e assessed . Th e P bremainin g i nth e lung wa s the nestimate dan drelate dt o th e tim e sinc e inhalation . Th e presen t experiment s differe dfro m thos e previousl y

reporte di ntha t (a ) mor e subject s wer e use d (b ) i nsom

e experiments , Inhalation s wer e o f les s duratio nan dmeasurement s o f lung burde nbega nver y soo nafterward s (c ) subject s wer e repositione di nth e countin g equipmen t severa l time s t o reduc e error s (d ) a variet y

o f leadaerosol s wa s used . 6. 3 Result s o f lun g clearanc e experiment s Th e wind-tunne l andaggregate dbo xaerosol s describe di nSectio n5. 2 wer e use d fo r thes e measirements . Th e inhalation s usuall y laste dfo r 3- 6 minute s an dth e firs t ches t measuremen t wa s mad e a t 5- 8 minute s fro m th e mid-time o f the inhalation . Measurement s wer e continue dt o a t leas t 12 0 hr s andwit hth e carbonaceou s aerosol s t o 26 0 hr s afte r inhalation . Th e result s ar e show ni nFigure s 6. 1 t o 6. 5 (i na lo g xlo g presentation) . I neac hexperimen t ther e i s excellen t agreemen t betwee nsubjects . Th e mea nclearanc e curve s fo r eac htyp e o f aeroso l ar e compare di nFig . 6.6 . Th e earl y clearanc e characteristic s ar e ver y simila r bu t ther e i s some separatio nby typ e o r aeroso l a t late r times . Th e solubl e compoundPb(NO,) , andth e ver y finel y divide d wind-tunne l aerosol s wer e reduce dt o \% residu e i nth e lun g mos t rapidl y (60-6 0 h ) wherea s th

e carbonaceou s exhaus t aeroso l wa s onl y reduce dt o 10*1 a t 10 0 h . Th e

-65 -result s wit hothe r aerosol s - clea nexhaust , exhaus t expose dt o sunlight , and Pb O - li e

clos e togethe r betwee nthes e limits . Th e clearanc e o f the variou s exhaus t aerosol s i s plotte di n Tl* . 6. 7 o n lo g xlinea r axe s and Compare dwit hdat a previousl y publishe d (Chamberlai ne t al . 1975) . The curve s ar e no t simpl e singl e o r dcubl e exponentia l functions , bu t ca n b e fitte db y a aerie s o f exponentia l terms , th e goodnes s o f fi t improvin g wit hth e numbe r o f terms . A fai r fi t ca n b e obtaine dwit hfou r terms . Th e resultin g half-live s and contribution s ar e liste di n Tabl e 6.1 . Tw o o f th e clearanc e curve s (leadnitrat e an d wind-tunne l exhaust ) ar e wel l represente db y thre e terms , having n o lon g half-lif e component . I f the aggregate dcarbonaceou s aeroso l i s omitte d fro m Tabl e 6.1 , th e patter ni s ver y similar , approximatel y 22% cleare dwit hT, = 0. 8 h , 34* ? wit hT ^ a 2. 5 h , 13% wit hT ^ = 9 han d \2% wit hT ^ = 4 4 h . Thi s reflect s th e basi c similarit y

o f the curve s i n Fig . 6.6 . Th e curv e fo r carbonaceou s aeroso l i s clearl y different , wit hlonge r half-live s fo r a substantia l fractio no f th e deposit . Th e similarit y

i n clearanc e o f exhaus t aerosol s and oxid e aerosol s fro m th e lung i s surprisin g whe ncompare dwit hth e i nvitr o solubilitie s o f th e same aerosol s measure dby

a smal l scal e continuou s flow techniqu e (Fig . 6.8) . Th e oxid e appear s les s solubl e i n vitr o tha nwoul db e expecte dfrc m th e rat e a t whic hi t i s take nu p fro m th e lung . Thi s coul db e ascribe dt o mor e efficien t flow an d transfe r i n th e lung . Howeve r th e nitrat e and exhaus t aerosol s ar e fa r mor e solubl e i n vitr o tha ni s apparen t fro m th e lun g measurements . Thi s i s possibl y becaus e th e mechanis m fo r transferrin g leadfro m lung flui dt o bloo di s a relativel y slow proces s whic hdetermine s th e overal l transfe r rate . Wit hth e exceptio no f th e carbonaceou s aerosol , th e residua l lea dlef t i n th e lun g wa s les s tha n\% o f tha t deposite da t seve nday s and wa s stil l falling . Wit hth e 20 3 carbonaceou s aerosol , th e radioactiv e half-lif e o f P bi s no t long enoug ht o permi t a simila r determination , bu t a t 1 0 day s th e residua l leve l wa s probabl y les s tha n7% andstil l falling . Barr y (1975 ) analyse dtissue s fo r leadpos t mortem an d foundn o concentratio no f lea di n lun g tissu e relativ e t o othe r sof t tissue . Thi s suggest s tha t almos t al l th e leadaeroso l i s absorbe dfro m th e lun g o r cleare db y othe r mechanisms . 6. 4 Transfe r fro

m lung t o bloo d 203 r Severa l venou s bloo dsample s wer e take nafte r inhalation s o f Pb , an d Fig . 6. 9 show s the entr y

o f 203 „ 

# I P b int o bloo d fro

m th e lung . I n thi s an d othe rfigures , erro r bar s indicat e - 1 SE . Th e for m o f th e curve s i s ver y simila rt o thos e obtaine d pre viousl y i n th e 1973/ 4 serie s o f

experiment s wit h Pb-labelle d exhaus tan d als o t o thos e obtaine d wit h nP b attache d t o condensatio n nucle i i n ai r(Booke re tal . 1969) . Thi s agai n show

s tha tth e chemica

l for m o rth e lea d i n sub-micro n size d particle s mad e littl e differenc e t o th e clearanc e fro m th e lun g an

d transfe rt o blood . Th e leve l o f 203 „ P b i n bloo d reache d a pea k about3 0 h afte rinhalation . A tthi s tim e th e amoun ti n blood , calculate d by multiplyin g th e specifi c activit y i n th e sample s b y th e subject' s bloo d mass , wa

s abou t60% o f

th e Initia l lun g burden . A s discusse d belo w I n Sectio n 7 , thi s doe s no tmea

n tha t40 * i s stil l i n th e lung , sinc e a simila rpercentag e i s foun d i n bloo d afte rsalin e injection .
-66 -

•»• > I I )J . 1 'l.BJH-1'U.'ll'.U.-U.!' . -.JU.ULI HP.6 8

6. 5 Dosag e o f stabl e lead I nthe inhalatio nexperiments , fo r a variet y o f reason s already

discussed , th

e quantit y o f stabl e leaddeposite di nth e lung s range dfro m 0. 3 t o 45 0 pg . Thi s compare dwit h5 p

g P bintravenousl y

Injected , an dfro

m 5-4 0 pg P babsorbe dfro m th e gu t i ningestio nexperiments . Fo r comparison , urba nexposur e a t 1 Mg Pb/ m an d50 X retentio nwoul dresul t i nth e depositio no f 8 M g P bpe r da y i nth e lung . The possi bilit y tha t th

e dosag e leve l o f lead affecte dth e result s need s examination . Two aspect s ca nb e considere d- lung clearanc e andpea k leve l i nblood . Lung clearanc e curve s fo r bo xexhaus t aeroso l (meanan dS.D . P bdeposite di n lun g 11 t

4 Mg) , wind-tunne l exhaus t aeroso l (1. 5 ± 1. 3 Mg ) an d bo xlea doxid e aeroso l (16 4 i 7 0 pg ) are show ni nFig . 6.10 . Thi s i s no t a stric t compariso no f lik e wit h lik e - th e wind-tunne l particle s wer e muc hsmalle r an dthe oxid e particle s wer e chemicall y

differen t fro

m an drathe r large r tha nth e aggregate dexhaust . Howeve r i t i s clea r tha t n o majo r differenc e i nlun g clearanc e wa s produced . Level s o f lea di nbloo d(a t 4 8 hrs ) are compare dfo r individual s i nFig . 6.1 1 an d i nnormalise dfor

m i nFig . 6.12 . Th e fitte dregressio nlin e show s a smal l positiv e slop e bu t th e relationshi pi s no t significan t a t th e 10 $ level .

-67 -.f,r - 7 -- • ,-. - ^jrnf - • P.6 9

Lun g clearanc e followin g ir . 20 3 o f Pb-labelle d aerosol s Compariso

n o f exponentia l co

i :nt s o f

th e observe d mea

n clearanc e curve s fo rs . differen taerosol s

Aeroso l
Clas s
Exhaus t

n

»

i t
Compoun d

t i Descriptio n

Aggregated , clea n Aggregated , clean , U.V . Wind-tunnel , clea n Aggregated , carbonaceous *
Pb O Pb(N0 3 ) 2 Componen thalf-live s and I

T m h 0. 6
0. 6
1. 2
0. 5

0. 5 1. 0 %
1 6
2 3
27
2 9

2 5 2 6 I I

h 2. 6
2. 7
2. 3
4. 5

2. 9 2. 2 *
3 6
3 1
3 9
5 0

3 2 3 3 percentag e contribution s

II I

T m h 8. 0
9. 1
8. 1
2 4

9. 8 %
3 6
36
3 4
6

2 5 IV

h 4 2
5 2

-
22 0

3 8 ! 10. 0 • 4 1 %
1 0
1 0

-
15

1 8

-

* Dat a fo rR.F.H . omitted .

-68 -

### 10 0

A . I 

### c

3

O t 

### c o E

O l O 

### c
u « _ O L 

### 10r 

## 1 >



### " ~ •

+ AC C x MJ H (1 ) 0 MJ H 12 ) A D N (1 ) 0 D N (2 ) O DHF A
« MEAN S 

# I •I

-

• 1 i

O A

- \



### \ e \


# . V , •l-v e 100 0 1 1 1 0 Hour s elapse d A E.R. E R919 8 FI G 6.1 . PERCENTAG E O F DEPOSITE D 203 

### P b REMAININ G I N LUNG . WIN D TUNNEL

_ EXHAUS TAEROSOL S (0i02/im |

I SI 

## ? O l

c 3

O l c c o E « * O l o c u « _ 

## a . 1 0

1 x MJ H

O OHF A

•KF B

Jr . 

## I 0 1 1 1 0 10 0 Hour s elapse d AERE . R9198 . FI G 6.2 . PERCENTAG E O F DEPOSITE D 203 

### P b REMAININ G I N LUNG . U/ V EXPOSE D EXHAUS T AEROSO L 7/7/76 .

### 10 0

7 *-eorK&— ^

O l 

### c 3

O l 

### c c o E ? * 1 0
O l 

### o c O r u 

### '" " -^^oS**;- . 

# ^^^tft*^ . 

# ^r«k <

x MJ H

•MJ H + AC C

•RF H A D N C l ea n exhaus t

Carbonaceou s

i i 

### n i t 

### aeroso l

exhaus t N I I I I 

### aeroso l

i t I I I I



### I 0 1 1 1 0 10 0 Hour s elapse d A ERE . R9198 . FIG . 6.3A . PERCENTAG E O F DEPOSITE D 203 

### P b REMAININ G I N LUNG . CLEA N AN D CARBONACEOU S EXHAUS TAEROSOLS .

### 10 0

I

- J K > I O l

c 3

O l c
o 

### E 0 >
o » o 

### c d > 

### o i

_ 

### a > a . 

### *<&« , 0 MJ H 20/4/7 7 4 AC C 20/4/7 7

•RF H 18/5/7 7 A D N 18/5/7 7



# X 1 0 10 0 100 0 Hour s elapse d A E R.E.R919 8 FI G 6 3B . PERCENTAG E O F ?0 3 

### P b REMAININ G I N LUNG . CARBONACEOU S EXHAUS T AEROSOL S A

T TIMES>1 0 HOURS

.

i U

### 10 0

w I 

### c

O l 

### c O 

### E

O l 

### o 

## c tl 

## u tm 

### a » a . 1 0

0 1 xMJ H

• RF H O DHF A + AC C


# Ir* 0 5 

# i r 1 0 10 0 Hour s elapse d AERE

. R9198 . FIG

. 6 U. PERCENTAG E O F DEPOSITE D 203 

### P b REMAININ G I N LUNG

. LEA D NITRAT E AEROSO L 

# i
• 1*«•• # 

## o cc U J 

### < UJ 

# o X 

# o o < U J



# o z Z>



# o z z <

. o 

## ? «* • •o Q . 

## o o T . U J «f t

< 

## u . o x x x o u . - • z u . O < E Z O 3 f



## 6un j u; 6uiuiDUja

j a6ojueoja d -74

- 

# o 3 D . O U J 

## Xo u . o U J 

# o < U J 

# o cc U J 0 . IT ) t o 

# d

C O 

### o > o c ix i 

# a U J <I O l 

### c 3

O l


### ' c 5 E

O l O



### « • o .

A E 0* 1 1 0 1 0 Hour s elapse d RE . R9198 . FI G 6.6 . COMPARISO N O F TH E LUN G CLEARANC E O F VARIOU S LABELLE D AEROSOLS . 10 0
20 3 P bP.7 7



### 10 0

O t 

### c 3

O l C O 

### E ft ft O t O 

### c ft o ft 

## a. 

# T — r 

# r

T

# r —

T

# i 1 — 1973-7 4 dat a singl e - subjec t

——— - 1976-7 7 dat a multi-subjec t

1 0 2 0 8 0 10 0 12 0 Hour s elapse d 14 0 16 0 18 0
A E R.E . R9198 . FIG . 67 . CLEARANC E O F VARIOU S EXHAUS TAEROSOL S FRO M TH E LUNG .

-76 -P.7 8 -"nr "



### lOOart :

• o ft 

### > " o ( A l/ l 

## "* 5 c 3 ft O ) 

### o c ft 

### o tm ft Q L 

### 1 0

1

2 3 4 5 I n vitr o solubilit y curves , a t a constan t rat e o f 0 5 m l pe r minut e : - Exhaus t aeroso l Exhaus t aeroso l Lea d nitrat e aeroso l Lea d oxid e aeroso l Lea d oxid e aeroso l __Mea n lun g clearanc e curv e ( oxid e /

nitrat e /

exhaus t aerosols ) 

# i I 1 0 2 0 3 0 4 0 5 0

Minute s elapse d 6 0 7 0 6 0 9 0
A.E.R.E.R9198.FI0.68 . COMPARISO N O F I N VITR O SOLUBILITIE S WIT H LUN G CLEARANCE .

-77 -O B I 

### 10 0

8 0 

## 6 0 4 0

o o 

## 2 2 

## 0

x » Q . O

o i 

### o 

## c ft 

### u 1 0 8

1 

## PbCl2_J° .VinejnJSillo n



# 1

_

L



## _

L 

# X X J L 

# ± 0- 1 0 5 1 0 2 0 5 0 1 2 5 

## Tim e afte rintak e (h ) A.E.R.E . R9198 . FIG . 6.9 . LEVEL S O F 2 

### 0 3 

### P b I N BLOO D FOLLOWIN G INHALATIO N OF EXHAUS T

OXID E O

R NITRAT E AEROSOLS . OR INJECTIO N O F PbCI? .

### 100



# •»•••**•* . & w

I • 4 ( 0 O l 

### c 3
O l 

### c ] c o E ft « _ J Q Q . tn 

## o r> i " O ft 

### v i o C X ft " O ft O l


### "c ft u i . & 

### 1 0

1 0 

# •? •x * x ^ x 

# f l *x* » ^ • x • 

# v. - ^ * » X

* 

### x


# { x *

* * . 

### * x # #

X « X X « * • 

### x Aggregatedlbox ) exhaus t aeroso l (9 ) 11±4// g P b deposite d i n lun g

•n n Pb O n <3 > 164170/i g P b I I n I I

* Mea n curv e fo r win d tunne l exhaus t aeroso l (a ) 1 5* 1 3// g P b deposite d i n lun g x



# X X x X *



### 0 1 1 1 0 10 0 Hour s elapse d A.E.R.E.R9198 . FIG . 6.10 . LUN G CLEARANC E A TDIFFEREN TLEVEL S O F STABL E LEA D DEPOSITIO N0 1 t
_ 3 O JZ O D

T J O 

### o Xi 

# c Jm\ 

# a. o o C M

ft O l O 

### c ft 

### u ft C L



## 1 1 0 Stabl e lea d deposite d i n lun g (/ig ) A.E.R.E . R9198 . FIG . 6.11 . RELATIONSHI P BETWEE N STABL E LEA D DOSAG E AN D PEA KLEVEL S I N BLOO D FO R INDIVIDUA L SUBJECTS . 1000

0 0-18 -

T J 

### m > 

## x r~ m < 

### m c~ a i

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### a 

### r o o oA.E.R.E.R9198.FIG.6.12.NORMAL — t/ » 

### m o
** o 

### m r ~ > HION t n X 

### T J O J 

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### m 

### r n z </ »

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### r -ELEADDOSAGEA 

### z o w » » » 

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## 7 o O Ldap 

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### q

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## Normalise d percentag e o f 203 

## P b i n bloo d a t 4 8 hour s (Individua l subjec t mean s 55 % ) o v

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o 

## o

o o 

## 1

-

—

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## 1 1

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## x x x — w

X KX

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# 1 

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Z8 dP.8 3



### 7 . Injectio n Experiment s 7. 1 Objecto f

experiments Ther e wer e thre e mai nobjective s (a ) t o observ e th e patter no f distributio ni n plasma , re d cell s an d excret a o f leadwhic hha d entere dthe bloo di n a ver y shor t perio do f time ,

20 3 (b ) t o calibrat e th e respons e o f th e ches t counte r t o systemi c Pb , a s describe di n Sectio n6.2 , (c ) t o measur e urinar y and endogenou s feca l excretion . 20 3 Fo r thes e purpose s P bwa s injecte dintravenousl y a s PbCl . i n steril e norma l saline . 

### 7. 2 Method

s Solution s fo rinjectio n wer e mad e u p wit h pyrogen-fre e norma l salin e an

d wer e sterilise d b

y autoclaving . Carrie rlea d wa s adde d a tth e rat e o f

5 pg/ml . Th

e 203 activit y o f

P b injecte d wa

s i n th e rang

e 1. 0 - 1. 8 MCi

. Thi s enable d th e activit y

203 i n blood , urin e an

d fece s t o be followe d fo r14 days . Th e activit y o f

P b i n th e syring e wa

s measure d b y countin g a tasufficien tdistanc e fro m asodiu n iodid e scintil latio n crysta l fo rth e countin g efficienc y t o b e accuratel y reproducible . A tinterval s afte rinjection , 2 0 m

l o f venou s bloo d wa

s withdraw

n fro m a n arm , hepari n wa

s adde d an d cell s an d plasm aimmediatel y separate d b y centrlfuging . Fo

rearl y sample s ( 2 - I S min ute s pos tinjection) , th e bloo d wa s withdraw

n fro m th e non-injecte d arm. Th e tota l •as s o f bloo d fo reach subjec tha d previousl y been measure d b y a n isotop e dilutio n techniqu e employin g I-labelle d huma n seru m albumin . Thu

s th e concentratio n o f 20 3 20 3 P b i n venou s bloo d sample s wa s als o expresse d a s th e tota l P b i n blood , o ra s th e percentag e i n bloo d o f th e origina l injecte d dose . 20 3 7. 3 P

b i n bloo d followin g injectio n 7.3. 1 Interchang e wit h extra-cellula rflui d 20 3 Fig . 7. 1 show

s th e percentag e o f

a n intravenou s dos e o f

P b whic h wa s presen ti n th e bloo d o f thre e subject s a ttime s fro m 1 t o 20 0 mi

n afte rinjection . Th e percentag e o f

th e lea d i n bloo d whic h wa s i n plasm

ai s als o shown , an

d a 20** i separat e curv e show s th e percentag e i n plasm a i n a n experimen t i n whic hP bwa s 20 3 adde dt o bloodi n vitro . A t th e tim e o f the firs t sampl e (1. 5 min ) th e P bi n bloo drepresente donl y 45% o f th e injecte ddose . Th e sampl e wa s take nfro m th e othe r arm , bu t circulatio no f the bloo di s sufficientl y rapi dtha t mixin g shoul d hav e occurred . Th e percentag e fel l furthe r t o 34 $ a t 3 min . Result s fro m 3 subject s agree dwell . I t wa s impracticabl e t o tak e sample s fro m on e subjec t sufficientl y

rapidl y

t o follo

w th e tim

e scal e completely . From 4 mi n onwards , th e amoun t o f P bi n bloo dthe nrecovere dslowly , reachin g 59 # o f th e injecte d dos e a t 20 0 min . Othe r investigator s hav e foun d5 0 t o 60J

J o f injecte ddos e o f 21 2 20 3 21 0 Pb , P ban

d P bi n th e bloo do f huma nsubject s an d animal s afte r injectio n (fo r reference s se e Chamberlai ne t al . 1975) . Th e pea k activit y i n bloo dafte r inhalatio nals o represent s a simila r fractio no f th e Initia l lun g burde n (Sectio n6. 9 an

d Fig . 6.9) .
-82 -Th e fractio n o f

bloo d lea d whic h was i n plasm ashowe d arapi d fal l afte r injection , 63 % bein g attache d t o re d cell s a t1. 5 min . I n vitro , 55* 6 was attache d t o re d cell s afte r1 min . The unattache d fractio n i n viv o wa s 19 % a t 1 0 min an d les s tha n \% a t100 0 min .

20 3 7.3. 2 Level s o f P bi n plasm a 20 3 Fig . 7. 2 show s th e percentag e o f P bi n bloo dwhic hwa s i n plasm a a t time s fro

m 1. 5 mi n t o 3 0 hafte r injection . Result s obtaine dfollowin g inhala tio nan d ingestio nar e als o shown . Afte r inhalation , lea denter s the plasm a fro m th e lung fo r some hours , an d thi s maintain s a highe r percentag e tha nafte r injection . Fro

m 1 0 honwards , les s tha n0.3 % o f th e P bwa s i n plasma . Thi s i s a suc hlowe r percentag e tha nusuall y reporte dfo r stabl e lead . Cavalier i e t al . (1978 ) reporte d2 t o 3 % o f th e stabl e lea di n plasma . Howeve r the y adde d K.EDT A anticoagulan t t o bloo dbefor e centrifuging. Whe nEDT A wa s adde di n vitr o 20 3 t o bloo dfro

m a subjec t wh o ha d receive dPb , progressiv e detachmen t fro m red cell s wa s observed . I n th e presen t wor k hepari nanticoagulan t wa s used , and bloo dwa s centrifuge dwithi na ver y few minute s o f sampling . Hurs he t al.(1969) , 212 - usin g th e isotop e T" bfoun d0. 5 t o 1.5 % i n plasm a whe nheparinise dbloo dwa s centrifuge d1 5 mi n after collection . 7.3. 3 Transfe r fro

m bloo dt o site s o f storag e I t seem s tha t tw

o processe s ar e operating , a s previousl y propose db

y Stove r (1959 ) 20 3 (a ) a rapi dsharin g o f th e solubl e inorgani c P bbetwee nplasm a an d other extracellula r flui d(E.C.F.) , (b ) a rathe r les s rapi dattachmen t t o re d cells , whic hfurthe r deplete s th e plasma , reverse s th e concentratio ngradien t wit hE.C.F . and draw s some "^P bbac k int o blood . A s th e ultimat e leve l i n plasm a i s ver y

IOVN- , al l th e lea dwoul dretur nt o bloo d i f bloo dan d E.C.F . wer e th e onl y compartment s receivin g lead . I nth e ICR P standar d7 0 k g ma n th e volume s o f E.C.F . an d plasm a are: - plasm a 2. 8 1 easil y accessibl e E.C.F . 9. 8 1 les s accessibl e E.C.F . 5. 6 1 Thus th e rati o o f

volum e o f

plasm at o othe rE.C.F . i s i n th e rang e 3. 5 - 5. 5 dependin g o n accessibility . 20 3 A t3 min post-injection , 34 % o f th e P

b remaine d i n th e bloo d an d o rthi s 1/5 wa s i n plasma . I f th e plasm ai s assume d t o b e i n equilibri awit h th e E.C.F . 20 3 an d th e volun e rati o i s take n a s 4.5 , the n th e distributio n o f th e P

b betwee n re d cells , plasma , E.C.F . and othe rsite s ca n b e estimated . Tabl e 7. 1 show s possibl e distribution s a t3 min and a t2 4 h afte rinjection . Thi s suggest s tha tl/ 3 o f th e injecte d lea d passe s t o othe rsite s extremel y

-83 -P.8 5

quickl y an

d ill e t/.i s fr^rcio n continue s t o ris e mor e slowl y wit h time . Ther e I s n o cer t•

) ".•.it; / .fex lY.i. storag e location s a t3 mi n an d 2 4 h ar e th e same . B y referenc e t o ra^za jxpe r.stents , th e mostimportan tstorag e sit e fro m a fe w hours 21 0 onward s i s probably bone . Hackettan d Siko v (1977 ) injecte d rat s wit h P b an d sacrifice d the

m seriall y i n groups . I n th e grou p kille d 9 0 mi

n afte rinjection , 30 % o f th e origina l dos e wa s i n th e skeleton , an d thi s increase d onl y slowl y t o 40 % i n th e grou

p kille d a t11 days . 7.3. 4 203 , P

b i n bloo d fro

m on e da y onward

s 203 „ Th e pea k concentratio no f P bi n bloo d wa s reache d abou t 1 0 hour s after injection , a t whic htim e a n averag e 59 % o f th e dos e wa s i n blood . Simila r pea k percentage s o f th e retaine d dos e wer e foun d afte r inhalatio n(Tabl e 7.2) . Thi s i s furthe r evidenc e tha t littl e o f th e lun g burde nwa s store d i n lymp hnode s o r remove d b

y ciliar y actio nan

d swallowed . Ther e wa s som e differenc e betwee n subject s (Tabl e 7.3 ) bu t thi s ma y hav e bee ncause d b

y error s i n estimatio no f bloo d mass . I f Instea d o f th e resul t 5. 7 k g fo r HJH' s bloo d mas s obtaine d b y thi s method , ther e i s substitute d a figur e o f 5. 1 k g estimate d fro m HJH' s heigh t and weight , th e entry i n Tabl e 7. 3 i s reduce d fro m 70 % t o 63% . 20 3 Th e concentratio no f P bi n bloo d decline d fro m 1 da y after injectio n exponentiall y

(Fig . 7.3) , til l 1 4 days , beyon d whic htime radioactiv e deca y mad e th e measuremen t inaccurate . I n Tabl e 7. 4 th e biologica l half-live s i n bloo d followin g injection , inhalatio nan d ingestio nar e compared . Th e difference s i n half-lif e betwee nmode s o f entry ar e o f doubtfu l significance . Wor k wit hth e 20 4 stabl e isotop e P bb y Rabinowit z an

d hi s colleague s a t UCLA , reviewe d i n Sectio n10.3 , show s tha t remova l o f lead fro m bloo d continue s t o follo w a n expo nentia l law

fo r a s long a s 10 0 day s afte r exposur e cease s (Fig . 10.2) . Th e biologica l half-live s show ni n Fig . 10. 2 ar e 18 , 24 , 3 6 an d 1 8 day s fo r UCL A subject s A , B , D and E respectively . Thu s th e mea nP bhalf-lif e o f 1 8 day s fro m th e injectio nexperiment s (Tabl e 7.4) , thoug hmeasure d ove r a perio d o f onl y 20 4 1 4 days , agree s wit htha t o f P bi n two o f th e UCL A subjects .

-84 -P.8 6 H"TT^ - i—TTI^HW TM

TABL E 7. 1 20 3 Possibl e distributio n o f P b afte rIntravenou s salin e injectio n

Locatio n

Re d bloo d cell s Plasm a E.C.F . Othe rlocation s (b y difference ) 20 3 Percentag e o f

injecte d P

b

a t3 min 2 8 7 3 2 3 3 a t2 4 h r

5 5 

# ]. '
4 4

Tabl e 7. 2 20 3 Mea n percentag e o f

absorbe d P

b appearin g i n bloo d a tth e pea k fo rvariou s group s o f experiment s

Mod e o f Intak e Inhalation , aggregate d aerosol , 197 4

" " " , 1976- 7 Inhalation , wind-tunnel , 1975

" , 197 7 Salin e injection , 197 4

" " , 1977 Ingestion , fasting , 1977 Ingestion , wit h food , 1977 20 3 Peak P

b i n bloo d ( % o f uptake ) 50. 6 56. 0 50. 6 55. 4 58. 0 58. 9 53. 0 50. 1 S.D .

5. 8 8. 5 8. 7 5. 6 6. 8 5. 0 9. 3 12. 2 S.E .

1. 7 3. 5 3. 6 2. 3 3. 2 1. 8 2. 7 3. 5

-85 -P.8 7

TABL E 7. 3 203 . Pea k level s o f P bi nbloo dfollowin g intravenou s inlection . Compariso no f subject s wit hmor e tha non e administratio n

Subjec t

AC C

D N

MJ H 20 3

Peak P

bi n bloo

d ( % o f uptak e 197 7
55. 3 53. 6
57. 1 57. 9
70. 0 197 4
55. 0

51. 5

69. 0

TABL E 7. 4 203 , 

### Biologica l half-live s o f P b i n bloo dfollowin g intravenou s salin e injectio n comparedwith othe r modes o f

intak e (Individua l value s fo rsalin e injectio n experiments )

Subjec t

AO C

D N

MJ H AC W P L KF B ANB S
Mea n

, Observe d half-lif e i nblood (T.

Salin e 197 4

-

22. 0

14. 9

-

- 13. 6

- 18. 3 injectio

n 197 7 15. 3 15. 7 20. 9 23. 2 17. 4 21. 6 22. 8

13. 9 i 

# 1 1 3. 6 S.D . . 1. 1 S.E . Al l

inhalation s
13. 6 (3 )

20. 6 (2 )

16. 1 (5 )

-

- 16. 9 (1 )

- 16. 4 1 2. 2 0. 7 i n days )

Al l ingestion s
12. 9 (2 )

22. 3 (1 )

14. 0 (2 )

-

-

-

- 15. 4 i 6. 0 3. 6 

### (Figure s i n bracket s indicat e numbe ro f experiments )

-86 -~ i

i E



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. o Q . o JM 

# 1 u



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### « C L 

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O l o c 0 1 

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### 1 0

A E 10 0 Minute s elapse d R E R919 8 FIG . 71 . LEVEL S O F 203p b I N BL00 0 FOLLOWIN G INTRAVENOU S INJECTION S 203 , O F 'PbCt 2 

### I N SALIN E

### 10 0

a , 

### f o

E a o .

J D 

### a . C O 

## o C M 

### * o o o

a *

"c a o 

# S. 

# ~ T ' r Salin e injectio n Inhalation,exhaus t

exhaus t U/ V exhaus t Pb O Pb O Pb(N0 3 

### ) 2 

### ionlfastin g J PbCl 2 

# T

+ X 

### A
A o o * 

### ANB S MJ H DHF A KF B MJ H AC C OHF A MJ H AC C D N 

## 10/10/7 7

8/10/7 7 7 / 7/7 6 7/7/7 6 7/7/7 6 25/1 1 / 7 6 25/1 1 / 7 6 18 / 8 / 7 6 13/10 / 7 6 13/10/7 6

0 0 1 0 1 1 1 0 Hour s elapse d A.E.R.E.R9198 . FIG . 7.2 . PERCENTAG E O F 203 P b 

### - N 

### BLOO D I N TH E PLASM A 10 0

o o CO10 0

o o 

## A , 7 0

< D .• = I

o S

O 

## T 

# • r T r



# «^*(?

• X O A o 

### ® MJ H D N P L ANB S AC W AC C c r



# 1 1 I 

# 1 I I 

## 1 I t.0 8 0 12 0 24 0 28 0 32 0 16 0 20 0 Hour s elapse d A E R.ER919 8 FI0.73 . 203 P b I N BL00 0 NORMALISE D T O 10 0 A

T 60 h AFTE R INTRAVENOU S SALIN E INJECTIO N O F ?03 PbC« 2 ;P.9 1 20 3 8 . Excretio no f P b 8. 1 Objec t o f measurement s 20 3 Th e objective s o f measurin g P bi n urin e and fece s wer e (a ) t o compar e los s b y excretio nwit hth e declin e i n the whole-body coun t o f 20 3 th e subjec t afte r h e ha dreceive dP bb y inhalatio no r injection , (b ) t o determin e the rat e o f endogenou s feca l excretion , (c ) t o examin e whethe r excretio no f the radioactiv e lea dwa s a t a simila r rat e t o tha t reporte delsewher e fo r stabl e lead , b y comparin g P bi n excret a wit hth e level s i n blood , (d ) t o obtai ninformatio nabou t the metaboli c processe s o f excretion . A s wit hothe r aspect s o f th e wor k wit hPb , the conclusion s onl y appl y directl y

t o shor t ter

m processe s i n th e firs t two week s afte r th e lea dwa s inhale do r injected . 6. 2 Method s Complet e collection s o f

urin e wer

e mad e i n polythen e container s t o whic h carrie r lea d an d preservativ e ha

d been added . I n som e experiments a serie s o f shor tsample s wa s collecte d fo rth e firs t4 6 hours . Thereafte rdail y 24-hou rcollection s wer e analysed . A

s al l collection s of

urin e wer

e ove rspecifie d times , excretio n wa s expresse d pe rhou

ran d no tpe rlitre . I n earlie rwork , th e questio n wa s examined 203 whethe rurinar y P

b wa s bette rexpresse d pe rhour,pe rlitr e o rpe rg creatinine . A complete collectio n o f urine , i n 2

8 samples , wa

s mad e fo r14 days afte ra subjec t ha d receive d P

b b y injectio n o f

labelle d red cells . Th e mea n rat e o f

excretio n o f creatinin e wa

s 0.06 4 g/h with standar d deviatio n 0.00 9 g/h . Thu s th e coefficien t 20 3 o f variatio n fo rcreatinin e excretio n wa s 14% . Th e variatio n i n • P

b i n urin e expresse d perh

ro rpe rg creatinin e wa s simila ran

d bot h wer e les s than th e variatio n i n P b perlitr e o f

urine . I twa

s conclude d tha tther e wa s no advantag e i n measur in g creatinin e i f

al l urin e collection s covere d know n period s o f

time . 20*" i Th e P bi n the urin e wa s estimate db y placin g aliquot s o n a 1 5 c m diamete r sodiu m iodin e crysta l t o recor dthe gamm a emissions . Lea dtende dt o sor bo n precipi 20 3 tate s i n th e urin e an dthi s altere dthe countin g efficienc y fo r Pb . Wie nthi s wa s discovered , i t wa s correcte dpos t fact o b y analysin g the for

m o f the gamm

a spectrum . 20 3 Thereafte r 1 0 m l cone . HC I wa s adde dpe r litr e o f urin e t o kee pth e P bi n solution . 20 3 Complet e collection s o f fece s wer e mad e andth e P bconten t measured . A s voidin g o f fece s ma y

b e irregular , i t wa s necessar y t o averag e ove r severa l day s t o obtai n excretio nrates . I t i s usefu l t o relat e urinar y andendogenou s feca l excretio nt o th e leve l i n blood , thu s

rena l clearanc e (g/h ) = Amoun t excrete di nurin e pe r hou r •* * Amoun t pe r g o f bloo d
Fo r th e excretio no f substance s whic har e presen t i n plasma , th e denominato r i s some time s amoun t pe r g o r pe r m l o f plasma . Lea di s mainl y I nre dcells , bu t th e rat e o f a xo v 

## » v 

# V
-90 -P.9 2



### urinary excretio n i s possibl y relate d mor e t o lea d i n plasm

athan lea d i n whole blood . Often the plasm

alea d i s no tseparatel y measure d an d rena l clearanc e can the n onl y be expresse d perg o f

whole blood . 8. 3 Excretio n i n urin e Fig . 8. 1 show s th e rat e o f urinar y excretio ni n th e firs t 3 6 hour s afte r intak e o f "^P bb

y inhalation , injectio nan d ingestion . Th e result s ar e expresse da s per centag e pe r hou r o f th e uptake . Fo r inhalatio nexperiment s uptak e i s equate dt o th e 20 3 initia l lung burden . Fo r ingestion , i t i s th e P bremaining i n the body afte r 5 days , no t tha t presen t a t the tim e the urin e wa s excreted , whic hwoul dhav e include d 20 3 unabsorbe dPb . Followin g injection , urinar y excretio nwa s initiall y a t th e rat e o f \% pe r hour , bu t decline drapidl y a s th e fractio no f P bi n plasm a decline d (Fig . 7.2) . Fro

m 4 hours , the excretio nrat e decline donl y slowly . Th e excretio n followin g inhalatio nals o decline dwit htime , bu t the initia l rat e wa s no t s o hig ha s 20 3 following injection , a s i t too k som e hour s fo r th e transfe r o f P bfro m lun g t o blood . Th e graph s fo r excretio nafte r ingestio ni n Fig . 8. 1 show a pea k afte r 4 hour s (ingestio nwhil e fasting ) an d 8 hour s (ingestio nwit hfood) . Th e delaye dappearanc e o f th e pea k i s relate dt o th e tim e fo r absorptio nfro m the gut . I n Fig . 8. 2 th e urinar y excretio nafte r inhalatio no f 5 differen t aerosol s b y on e subjec t i s shown , an dals o the excretio nafte r 4 subject s inhale dPb O aerosol . I nth e uppe r par t o f Fig . 8. 3 i s show nth e urinar y

excretion , a s percentag e o f 20 3 the initia l bod

y burde no f Pb , ove r th e perio d1 t o 1 4 days . The result s fo r salin e injectio nand inhalatio nar e simila r fro m 2 day s onward , and sho w a declin e wit h a half-lif e o f 1 9 days . Thi s i s simila r t o th e half-lif e i n blood , indicatin g a constan t rena l clearanc e rat e (Sectio n8.6) . Th e mea npercentag e excretio npe r da y 20 3 ove r th e perio d3-1 4 day s o f 6 subject s receivin g P bb y injectio ni s show

ni n Tabl e 8.1 . Th e urinary excretio nwa s fairl y consisten t betwee nsubjects , th e coefficien t o f variatio nbein g 8% . 

### 8. 4 Endogenou

s feca l excretio n I nth e lowe r par t o f Fig . 8.3 , feca l excretio ni n th e 1 4 day s followin g injectio n andinhalatio nar e compared . I n th e firs t 4 days , feca l excretio nwa s highe r afte r inhalatio ntha ninjection . Excretio no f aeroso l brough t u p b y mucociliar y

actio nand swallowe dma y

hav e contribute dt o thi s excess , whic hhoweve r onl y amount s t o a tota l o f abou t 3% o f th e initia l lun g burden . Th e percentag e endogenou s feca l excretio no f 6 subject s fro m 3 t o 1 4 day s afte r Injectio ni s show

ni n Tabl e 8.1 . Th e rati o F A J o f endogenou s feca l t o urinar y excretio nha d th e mea nvalu e 0.4 9 wit hstandar ddeviatio n0.15 . I t appear s fro m Fig . 8. 3 tha t endogenou s feca l excretio ni s establishe dwithi na da y o r two a t th e latest , allowin g fo r dela y i n voidin g th e feces . Chamberlai ne t al . (1975 ) reporte d F ^ = 0. 7 followin g inhalation . Th e figur e fo r the injectio nexperiment s i s slightl y lower , partl y

becaus e there'wa s som e smal l contributio no f swallowe dP bi n the inhalatio nexperiments , bu t mainl y becaus e tw

o subject s (ANB S and ACW) , whos e FA ) ratio s wer e la* , wer e no t Include di n th e earlie r series . Dat a fo r thos e subject s wh o too k par t i n al l th e serie s o f experiment s ar e compare di n Tabl e 8. 2 an d th e mea nvalue s

-91 -P.9 3

o f F / Ufo r inhalatio nand injectio nar e see nt o b e i n close r agreemen t thoug hth e •inhalationvalu e i s stil l th e large r o f th e two . Ratio s F A l o f 0. 7 an d 1. 1 hav e bee nfoun d i n tw o serie s o f measurement s o n * 21 0 baboon s injecte d wit hP b(Cohen , 1970 ; Strehlow , 1971) . I n rat s injecte d wit h •^Pb , F A * wa s abou t unit y (Morgane t al . 1977) . Harriso ne t al . (1966 ) injecte d a 4 7 fi*\ \W

22 3 health y ma n wit hCa , Sr , B a an d Ra an

d measure d excretio ni n urin e an d fece s fo r 8 day s afte r eac hinjection . Ratio s F ^ o f 0.4 8 (Ca) , 0.7 5 (Sr) , 9. 0 (Ba ) an d 3 6 (Ra ) wer e found . 8. 5 Tota l excretio n 203 „ Th e combine d rat e o f urinary an d feca l excretio no f injecte d P bwa s 1.24* * pe r 20 3 da y (Tabl e 8.1) . I f n o othe r rout e o f excretio ni s significant , th e amoun t o f P b i nth e subject , togethe r wit hhi s cumulativ e excretion , shoul d equa l initia l dose . Thi s wa s teste d i n 6 subject s afte r injectio n(tw o o f the m o n tw o occasions ) (Tabl e 8.3) . Th e result s showe d a ver y satisfactor y

balance , and i t ma y b e conclude d tha t othe r route s o f excretion , fo r exampl e i n sweat , ar e no t important . 203 „ 8. 6 Excretio ni n relatio nt o P b i n bloo d Tabl e 8. 4 show s th e rate s o f rena l clearanc e an d endogenou s feca l clearanc e ove r th e perio d 3-1 4 day s afte rinjectio n experiments . The rena l clearanc e rat e i s define d b y 20 3

Rena l clearanc e (g/h ) = A ^ r M S P^excrete d i n urin e pe rhour Averag e P

b pe rg whol e bloo d

an d similarl y fo rth e feca l clearance . The averag e rena l clearanc e o f 3.8 2 g/ h com pare s wit h 4. 5 g/ h (4. 3 ml/h ) foun d i n th e earlie rserie s o f inhalatio n experiment s (Chamberlai n e tal . 1975) . Keho e (I96ia ) roun d a n averag e bloo d lea d (PbB ) o f 2 8 ug/10 0 g an d averag e urinar y outpu t(PbU ) o r3 0 Mg/ d i n 1 0 norma l adults , whic h give s arena l clearanc e rat e o f 4. 5 g/h . Rabinowit z e tal . (1976b ) foun d averag e Pb B = 19. 4 Mg/10 0 g and Pb U = 35. 6 ug/ d i n 5 subjects , givin g rena l clearanc e o f 7. 7 g/h . Ther e i s evidenc e from Kehoe 1 s (1961b , 1966 ) wor k wit h subject s give n ora l dose s o f lea d tha tPb

U increase d more rapidl y tha n PbB , s o tha trena l clearanc e rates , whe n expresse d relativ e t o whol e blood , increase d wit h increasin g PbB . Ther e hav e bee n fe w measurement s o f endogenou s feca l lea d i n humans , owin g t o th e difficult y o f distinguishin g i tfro m unabsorbe d dietar y lea d i n feces . Rabinowit z e tal . (1976b ) 20 4 gav e ora l dose s o f

th e stabl e lea d isotop e P b t o subject s dail y fo rperiod s o f

20 4 severa l months . Fro m 1 0 day s afte rcessatio n o f dosin g onwards , P b appearin g i n fece s wa s ascribe d t o endogenou s feca l excretion , an d analysi s o f thes e dat a (Tabl e 10. 4 below ) show s tha tth e rat e wa s equivalen tt o 2. 5 g/h , compare d wit h 1.8 2 g/ h fo rth e AER E subject s i n Tabl e 8.4 . B y dividin g th e estimate d bloo d mas s o f th e subject s by th e tota l ( F • U ) rat e o f excretion , aclearanc e half-lif e i n day s i s deduce d i n th e las tcolum n o f Tabl e 8.4 . Thi s woul d b e th e half-lif e o f P b i n bloo d i ral l excretio n wer e from tha tcompart men tan d ther e wer e n o transfe rfrom bloo d t o othe rsite s o f storage . I n Tabl e 8. 5 th e bloo d half-lif e (T^ ) calculate d i n thi s wa y i s compare d wit h th e half-lif e calculate d
-92 -P.9 4

s fro m the declin e o f P bi n bloo d(Fig . 7.3) . O n averag e T ^ calculate dfro m Ff i • U i s 50 % highe r tha ntha t calculate dfro m the venou s bloo dresults . Thu s ove r th e 20 3 perio d3-1 4 day s ther e wa s a ne t los s o f P bfro m bloo dt o othe r storag e site s a t a mea nrat e o f 1.2 % o f bloo dlea d(o r 0.5 % o f whol e body lead ) pe r day . I f instea do f usin g th e tota l clearanc e rate s i n Tabl e 8.4 , th e bloo dmas s i s divide db

y feca l clearance , th e averag e resul t i s 303 0 hours , o r 12 6 days . Thi s

20 3 woul db e th e mea nlif e o f P bi n bloo di f excretio ntoo k plac e b y th e feca l rout e only . On e sourc e o f endogenou s feca l excretio ni s th e bile , an don e possibl e sourc e o f leadi n th e bil e i s th e destructio no f dea dre dcell s i n th e liver . Th e mea n lif e o f redcell s i s reporte dt o b e 12 0 days , s o th e rat e o f endogenou s feca l excretio n correspond s t o thi s rat e o f destruction . However , othe r elements , suc ha s th e alka lin e earths , *tfiic

har e no t preferentiall y concentrate di n th e re dcells , ar e als o excrete dvi a th e fece s (Harriso ne t al . 1966 ) and th e scavengin g o f moribun dre dcell s by th e live r coul dhardl y accoun t fo r th e endogenou s feca l excretio no f thes e elements .

20 3 8. 7 Relatio no f urinar y excretio nt o P bi n plasm a 20 3 Tabl e 8. 6 show s measurement s o f P bi n collection s o f urin e an di n plasma followin g a salin e injection . Th e bloo dwa s centrifuge dwithi na minut e o r tw o o f sampling . Fig . 8. 6 show s th e rena l clearanc e expresse da s 20 3 rena l clearanc e P bexcrete di n urin e pe r minut e 203 , P b pe rm l o f plasm a Graph s ar e give n fo rth e ingestio n experimen to f Tabl e 8.6 , fo rth e mea n o f 7 inhala tio n experiments an

d fo ra fastin g ingestio n experiment . Th e plasm a rena l clearanc e rat e increase d t o a pea k 1 hourafte rinjection . Afte rinhalatio n an d ingestio n th e pea k wa s later , owin

g t o th e dela y i n uptake . Th e reaso n fo rth e pea

k i s no tknown

. Irrespectiv e o f

mod e o f administration , th e plasm a rena l clearanc e wa s abou t3 0 ml/min fro m 1 2 hour s onwards . Glomerula rfiltratio n rate s o f orde r10

0 ml/min ar e loun

d fo r a numbe ro f substances , fo rexampl e Na , K , Cl , creatinin e an

d glucos e (Bes t& Taylor , 19C1) . Th e mea n urinar y excretio n a t3-1 4 days afte rinjectio n wa s 0.83 % o f

th e injecte d dos e pe rda

y (Tabl e 8.1) , equivalen tt o 5. 8 * 10 pe rmin . Ove rtha tperio d about 47 % o f th e injecte d P

b wa s i n blood . Th

e averag e bloo d mas

s wa s 523 0 g , bloo d 203 volun e 5000 m

l an d plasm a volum e 274 0 ml . Th

e mea n percentag e o f

P b i n bloo d tha t wa s i n plasm

a ove rth e perio d 1 0 t o 10 0 hour s wa s 0.24 % (Fig . 7.2) . Henc e th e rena l 20 3 clearance , relate dt o P bi n plasm a wa s 5. 8 xiQ" 6 x274 0 2. 4 xio" 3 x0.4 7 = 1 4 ml/min .
Harriso ne t al . (1966 ) foun d(plasma ) rena l clearance rate s ( 1 t o 8 day s afte r injec tion ) o f 2.4 , 7.6 , 7. 1 and 2. 4 ml/mi nfo r radioactiv e isotope s o f Ca , Sr , B a an dR a respectively .

-93 -TABL E 8. 1 

### 20 3 Excretio no f P bfollowin g intravenou s salin e injectio n 197 7 serie s
Subjec t

AC C (1 ) (2 ) D N (1 ) (2 ) P L AC W MJ H ANB S Mean S.D . C V . 20 3

Percentag e o f

injecte d P

b excrete d pe rda y (perio d 3-1 4 days ) U 0.9 0 0.8 3 0.8 1 0.8 5 0.7 2 0.7 8 0.9 2 0.8 7 0.8 3 0.0 7 8 % F e

0.5 0 0.6 1 0.3 4 0.3 9 0.3 6 0.1 9 0.5 8 0.3 1 0.4 1 0.1 4 34 % 

# Vu

0.5 6 0.7 3 0.4 2 0.4 6 0.5 0 0.2 4 0.6 4 0.3 6 0.4 9 0.1 5 33 %

TABL E 8. 2 Compariso no f endogenou s feca l an d urinar y

excretio n i ndifferen t serie s o f experiment s

Subjec t

AC C

MJ H

D K

Mea n F e / U 20 3

Percentag e o f

initia l P

b excrete d pe rda y (perio d 3-1 4 days ) Salin e injectio n 197 4 an d 197 7 U 0.9 0 0.8 3

0.9 2

0.8 1 F e

0.5 0 0.6 1

0.5 8

0.3 4 0.8 5 ; 0.3 9

i 

## i 1 0.8 6 0.4 8 0.5 6 Inhalatio n

197 3 - 197 7 U 0.6 2 0.4 8 0.6 6 0.8 3 1.2 3 1.0 1 1.3 0 0.8 9 0.7 2 0.6 3 0.6 6 F e

0.5 6 0.6 6 0.4 6 0.5 9 0.5 6 0.6 6 0.6 6 0.4 0 0.3 2 0.4 0 0.5 3 0.6 1



### -94 -T T""' w T T r
TABL E 8. 3 203 , Accountin g fo r P bi n salin e injection s (197 7 series )

a ii : J50 3 Th e sum o f whol e body , feca l an d urinar y P ba s a percentag e o f th e quantit y

injecte d
DA Y
1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 Subjec t

MEA N OVER A L L MEAN ACC , 100. 2 98. 4 97. 7 98. 9

98. 3

96. 8

94. 4

97. 8 ACC 2

99. 8 96. 0

96. 7

93. 0

93. 3

95. 8 W l

99. 2 100. 0 100. 0 97. 7

98. 0

98. 3

101. 0

102. 4 99. 6 DN 2

102. 1 103. 4

101. 4

100. 9

105. 4

113. 7

86. 4 101. 9 9 9 . MJ H

100. 0

98. 0

97. 6

99. 5

102. 9

95. 1 102. 4 99. 4 7 ANB S

100. 2 101. 4
102. 2

99. 7

103. 1

107. 2 102. 3 P L

99. 2 99. 5 97. 9 98. 0

98. 6

97. 0

97. 6

105. 7 99. 2 AC

W 99. 6 99. 5 99. 0 100. 8

101. 0

101. 4

102. 3

109. 9 101. 7

TABL E 8. 4 20 3 Urinar y an d feca l excretio no f P brelativ e t o concentration s

i nwhol e bloo dfollowin g injectio n

Mea n S.E . Subjec t
AC C (1 ) AO C (2 ) D N (1 ) D\ i (2 ) P L AC W MJ H ANB S Bloo d

mas s (g ) 410 0 410 0 550 0 550 0 500 0 550 0 570 0 560 0 Rena l

clearanc e (g/h ) 3.7 8 3.4 6 4.0 5 4.1 6 3.4 5 3.8 9 3.5 4 4.2 6 Feca l

clearanc e (g/h ) 2.0 8 2.5 4 1.6 2 1.9 1 1.7 3 0.8 5 2.2 5 1.5 2 Tota l

clearanc e (g/h ) 5.8 6 6.0 0 5.6 7 6.0 7 5.1 6 4.7 4 5.7 9 5.7 8 I Bloo d mas s

Tota l clearanc e (h ) 70 0 68 3 97 0 90 S 96 5 116 0 98 4 96 9 Clearanc e

half-lif e (d ) 20. 2 19. 7 28. 0 26. 2 27. 9 33. 5 28. 4 

### 28. 0 1 3.8 2 0.1 1 1.6 2

0.1 6 5.6 4

0 . H i

-95 -P.9 7 TAB U 8. 5 203 „ Compariso n o f

th e observe d biologica l half-lif e o f P b bloo d wit h th e calculate d {F c+ U ) half-lif e from Tabl e 8. 4
Subjec t AO C D N P L AC W MJ H ANB 5 

### No . o r observation s 2 2 1 1 1 1 Half-lif e (T^ ) (d )

Observe d 15. 5 22. 2 22. 8 21. 6 16. 2 13. 9 Calculate d (F f i + U ) 20. 0 27. 1 27, 9 33. 5 28. 4 28. 0 Mea n Rati o 1.2 9 1.2 3 1.2 2 1.5 5 1.7 5 2.0 1 1.5 1

TABL E 8. 6 203 , Relatio nbetwee nP bi n urin e an d plasma , 0-4 6 hour s

Salin e Injection s 197 7 Subjec t MJ H

Perio d 0-0. 5 0.5-1. 0 1.0-1. 5 1.5-2. 0 2.0-2. 5 2.5-3. 0 3.0-3. 8 3.8-4. 7 4.7-6. 1 6.1-7. 6 7.6-9. 6 9.6-16. 5 16.5-18. 5 18.5-20. 5 20.5-24. 3 24.3-27. 5 ! 27.5-35. 5 i 35.5-45. 5 203 P b i n plasm a

nCi/ln l 1.2 6 x io" 2 3.7 4 x io" 5 2.4 0 x IO - 3 2.0 0 x iO" 3 1.7 2 x IO" 3 1.5 2 x 10" S 1.3 5 x 10~ 3 1.2 2 x IO" 3 1.0 7 x IO" 3 9. 5 x IO" 4 8. 6 x IO" 4 6. 8 x IO" 4 6. 2 x IO" 4 5. 7 x IO" 4 5. 2 x IO" 4 5. 0 x iO" 4 4. 8 x io" 4 4. 2 x iO" 4 2 0 %

* P b i n urin e nCi/ h 30. 9 17. 7 13. 7 6.7 4 4.8 6 3.0 9 1,1 8 1.0 2 1.3 8 1.4 8 1.6 3 0.7 2 0.9 8 1.2 4 0.9 8 0.7 4 0.8 5 0.8 9 Volun e o f plasm a

cleare d o f 203p b pe r mi n 40. 9 78. 9 95. 1 56. 2 47. 1 33. 9 14. 6 13. 9 21. 5 26. 0 31. 6 17. 6 26. 3 36. 2 31. 4 24. 7 29. 5 35. 3

-96 -P.9 8

3 O

C l O i 

### c

u X 0 >


## o a 3

aV o > o c « l u L . 4 / 

### a .

1 2 1 6 2 0 Hour s elapse d AERE . R9198 . FIG . 8.1 . RATE S O F EXCRETIO N O

F 20 3 Pb I N URIN E DURIN G TH E FIRS T34H0UR S FOLLOWIN G INTAK E

-97 -P.9 9 

# ^ 1

9 O £.
%m 

## a c
tm 3 

### c
• o

u

J C 

### o O L 

## a . f > o rs i


### * a c u a 

## a .

0 0 1 1 2 1 6 2 0 

## Hour s elapse d A.E.R.E.R9198 . FI G 82 . RAT E O F EXCRETIO N O F 203 

### P b I N URIN E DURIN G TH E FIRS T 36H0UR S AFTE R IN H A L ATION . C OMPAR I SO N O F ti ) FIV E DIFFEREN T AEROSOL S FO R ON E SUBJECT . I.i ) FOU R DIFFEREN T

SUBJECT S FO R ON E AEROSOL .
-98 -P. 1 i-fT^'^'wri *

3 0

2 0

o

a . 1 0 

## i r

3 0

2 0

1 0 

## i 

## 1 1 1 1 r

INHALATION S 1973/7 4 x Urin e
•Fatct i 

# i



# r

I 1 1 L

1 V

. SALIN E INJECTION S 197 7 

## i 

## r



# ^-i— h J L



# i— I ' I 1 I I I I L

A E t 5 6 7 6 9 1 0 1 1 1 2 1 3 U Ooy * R E R919 8 FI G 6 3 EXCRETIO N O F 203 P b I N URIN E AN D FAECE S FOLLOWIN G (o l INHALATIO N O F HQTQ R EXHAUS T AEROSOL S AN D Ib l I V INJECTIO N O F Z03 PbCt ?

-99 -

# ? 9 0 -
8 0

J* 0 . o o < N M 

### _ O T J 

### « k O 

### * u o E o Q . *o C 

### E 2 : E 7 0
6 0
5 0
4 0
3 0
2 0
1 0



### 0 1 T

### 1 I r wSolin g injectio n (1 )

———Mea n o

f 7 inhalation s

—-—Ingestion , fastin g ( 1 )



# 1 1 0 5 1 1 0 5 0 10 0

Hour s elapse d A.E.R.E.R9198 . FI0.84 . EXCRETIO N OF 203 

### P b I N URIN E EXPRESSE D I N TERM S O F BLOO D PLASM A 2 0 3 

### Pb . COMPARISO N O F INTRAVENOU S SALIN E INJECTIO N AN D INHALATIO N . ,P. 3

20 3 9. - Ingestio nexperiment s wit hP b 9. 1 Objec t o f experiment s Mos t peopl e inges t muc hmor e lea dthanthey inhale , bu t tin : percentag e uptak e fro m the gu t i s ofte nquote da s abou t 10 % wherea s th e Inhalatio nexperiment s wit h Pbshow tha t uptak e fro

m th e lun g i s virtuall y complete . Th e figur e o f 10 % uptak e fro

m gu t i s howeve r no t ver y securel y

based , and severa l line s o f evidence , reviewe di n Sectio n1 0 below , sugges t tha t th e percentag e uptak e ma y b e higher . 20 3 Some measurement s o f uptak e fro m gu t wer e therefor e mad e wit hPb . A detaile d stud y o f th e effec t o f die t o n uptak e o f leadwa s no t attempted , bu t an attemp t wa s mad e t o estimat e th e rang e i n norma l subject s b y measurin g uptak e unde r fou r condition s (a ) solubl e lea d(PbCl, ) take nafte r fasting overnight , (b ) solubl e lea

dtake nwit ha meal , (c ) insolubl e lead(PbS ) take nfasting , (d ) insolubl e leadtake nwit ha meal . A pane l o f 6 adul t mal e subject s too k par t i n thi s comparison . A fe w measure 20 3 ment s wer e mad e o f uptak e o f P bb y subject s wh o swallowe dfilter s whic hha d collecte dexhaus t aerosol . 9. 2 Method s 20 3 PbCl „ wit h7 5 ue stabl e PbCl , carrie r wa s administere di n 10 0 m l o f water . 20 3 Pb S wa s precipitate dfro m chlorid e solutio nb y rUS , separate db

y filtratio nthrough . a nA A millipor e dis c an

d washe dwit hdistille dwater . A smal l segmen t o f th e filte r 20 3 paper , carryin g a n appropriat e amoun t o f P band abou t 5 0 u g carrie r wa s swallowe d wit hwater . N o foo dwa s take nfo r 1 2 hour s befor e th e fastin g ingestion s no r fo r 20 3 2 ^ hour s afterwards . Fo r ingestio nwit hfood , th e P bwa s swallowe di n th e cours e o f a lat e breakfast . Thi s wa s a standardise dmea l o f bread , cheese , boile degg , mil k and a n apple . 20 3 Th e activit y

o f P bingeste dwa s suite dt o th e anticipate duptak e an d range d fro m 1 t o 5 LCi . Befor e ingestion , th e activit y o f P bt o b e administere dwa s measured , and al l vessel s wer e checke dfo r residue s afterwards . t ycw Th e amoun t o f P bi n th e subject' s bod y 5 day s afte r ingestio nwa s measure d i nth e 'whol e body ' counter . Thi s i s a n arra y o f si xsodiu

m iodid e crystal s arrange dabov e and belo w th e supin e subject . T o confirm tha t enoug htim

e ha d 20 3 elapse dfo r excretio no f unassorte dPb , th e measuremen t wa s repeate do n th e 6t h 20 3 and7t hdays . Th e P bi n venou s bloo dsamples , and i n excreta , wa s measure da s i n othe r serie s o f experiments . 9. 3 Uptak e fro

m th e gu t The observe d uptake s range d fro m 2% t o 60 % (Tabl e 9.1) . Th e presenc e o f

foo d reduce d th e averag e uptak e o f PbCl , by afacto ro f 6. 5 bu tth e effec twas les s marke d fo rPb S (facto r1.8) . Th e uptak e o f

PbCl - was greate rtha n tha to f Pb S by afacto r

-101 -P. 4

o f ». 8 fastin g bu tonl y by afacto ro f 1. 2 wit h food . The presenc e o f food , b y 

### incroeMh* abilit y i n th* tu*meh, nigh tmnlu - Pvi mer * solubl e •n

d availabl e for uptake . I n Tabl e 9. 2 result s o f th e presen twor

k ar e compared wit h result s o f Wetheril l e tal . (1975 ) wh

o use d astabl e isotop e techniqu e t o estimat e uptake . The result s 20 3 o f Blak e (1976 ) wh

o gav e ora l dose s o f

PbCl . t o subject s betwee n meals , ar e als o given . Ther e i s asingl e experimen to f th e latte rtyp e i n th e curren twor k whic h compare s well . The mai n discrepanc y i s i n th e uptake s observe d Torlea d sulphid e unde rfastin g condition s wher e Wetheril l e tal.' s valu e i s simila rt o tha tfo r chloride , wherea s th e Harwel l valu e i s lowe rb y afacto ro f 4 . I n Fig . 9. 1 th e percentag e uptak e fo reac h compoun d i s plotte d i n term s o f th e mod e o f intake . I ti s clea rtha tsubject s wit h hig h uptak e i n on e mod e ten d t o hav e ahig h uptak e i n th e othe rnod e and tha tfo rPbCl , th e correlatio n i s good . Tabl e 9. 3 show s th e hierarch y o f subject s arrange d accordin g t o th e orde ro f thei r percentag e uptake . Compariso n o f th e set s (a ) an

d (b ) show s tha tth e hierarch y i s nearl y th e sam

e whethe ruptake s fastin g an d wit h foo d ar e considere d separatel y o r take n togethe rb y averagin g th e percentag e uptak e fastin g and wit h food . The analysi s o f

th e position s o f

th e subject s i n se t(a ) shows tha tth e orde ri s no t random . I f

some subject s consistentl y tak e up ahighe rpercentag e o f ingeste d lea d tha n others , thi s wil l explai n th e variatio n i n bloo d lea d o f peopl e expose d t o simila rlevel s o f

lea d i n food , drin k an d air . Th e additiona l measurement s wit h exhaus taerosol s ar e summarise d i n Tabl e 9. 4 an ! ar e compare d wit h earlie rmeasurements . I n th e environmen tth e rout e b y whic h exhaus taeroso l enter s man's die tmight , i n part , b e du e t o actua l aeroso l materia l contaminatin g vegetation , surface s and utensil s (t o whic h th e dat ai n Tabl e 9. 4 ar e relevant ) o rmight , i n part , b e du e t o th e uptak e o f th e lea d b y vegetatio n an d it s incorporatio n int o plan ttissue . Th e lea d migh tthe n b e I n achemica l for m whic h resulte d i n differen tlevel s o f uptake . Experiment s t o explor e thi s prove d imposs ibl e becaus e th e lo w uptak e o f lea d b y th e plan tsystem s combine d wit h th e shor t half-lif e o f

th e P

b di d no tpermi tproductio n o f adequat e quantitie s o f labelle d materia l fo rthi s typ e o f experiment . A singl e ingestio n experimen twas undertake n usin g precipitate d PbCrO- . Thi s was o f

interes tbecaus e i ti s an extremel y insolubl e compound . I ti s howeve r slightl y solubl e i n HCl . Th e observe d solubilitie s o f th e labelle d compoun d were: - 0.45 % HC

l 0.8 8 Ug/m l 0.05 % HC

l 0.2 0 ug/m l distille d wate r0.01 2 ug/m l

20 3 On e subjec t(MJH

) ingeste d 2. 3 uC i o f PbCr0 4 associate d wit h 9 0 u g o rstabl e lea d a s chromat e immediatel y befor e anorma l midday meal . Th e observe d uptak e wa s 14 % ( atypica l valu e fo runspecifie d compounds and dietar y states) . Thi s represent s 1 3 u g o rlead . Assumin g th e solubilitie s give n abov e and astomac h acidit y (wit h food ) equivalen tt o 0.15 % fre e HCl , 1 3 u g o f P b woul d requir e avolum e o f onl y 3 5 m

l

-102 -P. 5

s o tha tth e obse - tup t<•.•.'•; « o f thi s salt , popularl y regarde d a s insoluble , i s no t unreasonable . I ti s dii"fi' V : t o Ci-iv e amea n percentag e uptak e o f dietar y lew d fro

m tin - ?0 3 result s wit h ' i>b. Thi s wil l depen d on th e chemica l natur e o rth e lea d i n th e diet . Th e result s i n fastin g subject s ma y mea n thn tlea d uptak e i s inrticularl y hig h whe n lea d i s ingeste d i n wate rand beverages , take n withou tfood . I f i ti s assume d tha taperso n i s i n balanc e fo rlead , th e uptak e from gu tan d lun g togethe rshoul d equa l th e urinar y and endogenou s feca l excretion . I n th e balanc e experiment s o rKehoe (1961b) , dail y ora l dose s o rlea d wer e give n and th e contributio n o rai rlea d t o th e tota l intak e was small . I n Sectio n 10.2 , Kehoe 1 s dat aar e re-examine d wit h th e additiona l assumptio n tha tth e rati o F Ai of endogenou s feca l t o urinar y excretio n ha d th e sam

e valu e o f

0. 5 i n Kehoe' s a s i n th e AER E sub ject s (Sectio n 8.4) . Wit h thes e assumptions , th e averag e uptak e o f lea d Tra

m th e gu tb y Kehoe' s subject s was 15 % (Table s 10. 2 and 10.3) . I n UCL A subject s give n ora l 20 4 dose s o rP

b a s nitrat e wit h meals , rathe rlowe rpercentag e uptak e was round (Tabl e 10.5) , bu twhe n th e dos e was take n Tastin g uptak e wa s muc h highe r(Tabl e 9.2) . 20 3 9. 4 Observation s on absorbe d P b following ingestio n 2 0 ^ 9.4. 1 P

b i n bloo d 20 3 Th e P b i n venou s bloo d followed aver y simila rpatter n t o tha tfollowin g inhalatio n o rinjection . A pea k wa s reache d arte r24-4 8 hour s a tamea n o r 52 % (S.E . 2%

) o rth e absorbe d lea d i n th e whol e bloo d volume . The dirrerenc e betwee n Tastin g and non-Tastin g experiment s i s no tsigniTicant , no ri s th e dirrerenc e betwee n intake s o rPbCl„ o rPbS . I n th e earl y stage s o ruptak e th e dirrerence s i n bloo d level s ar e signiTi can t(Fig . 9.2) . Followin g ingestio n o rPbCl , whils tTastin g th e appearanc e 20 3 o T P b i n bloo d wa

s slightl y delaye d relativ e t o tha tTro m Pb O i n lun g bu t reache d simila rlevel s arte r4- 5 hours . Howeverwhe n Pb S was take n wit h food th e dela y was mor

e marke d and equivalen tlevel s wer e no treache d unti l 2 4 hour s had elapsed . A simila rdela y wa s presen ti n th e plasm alevel s whic h ar e nor mall y a tthei rhighes timmediatel y arte rintake . Thi s was onl y observe d i n th e Tastin g experiments , th e lowe ruptak e i n th e presenc e o T Too d makin g plasm a determination s extremel y inaccurate . Th e peak leve l i n plasm aappear s t o b e delaye d b y 1- 2 hours . ATte rth e peak concentratio n i n th e bloo d ha d bee n reache d th e bloo d leve l decline d i n th e norma l wa y wit h asingl e exponential . The halT-liT e was deter mine d i n riv e case s (Tabl e 9.5 ) involvin g thre e subjects . Th e mea n halT-liT e o r15. 4 d wit h S.E . 2. 7 d doe s no tdiTTe rsigniTicantl y Tro m th e inhalatio n cas e althoug h th e P

b entere d th e bloo d vi ath e porta l instea d o T th e pulmonary circulation . 9.4. 2 Appearanc e o

T systemi c lea d following ingestio n O n on e occasion , following ingestio n oT Pb S wit h Too.l , s.ysi.mii tl»-ml , a s indicate d b

y P b presen ti n th e legs , was monitore d t o eomjur e th e change s

•103 -

### P. 6

wit hthos e observe d i n lun g clearanc e experiments . Th e observation s showe d a ris e t o a pea k leve l a t 2 4 hour s followe d b y a slow decline , simila r t o tha t o f 20 3 P bi n blood . However , a s migh t b e expecte d fro m the observation s o n bloo d 20 3 and urine , th e initia l increas e i n P bconcentratio nwa s delaye d bu t achieve d a pea k afte r a perio d o f 4 0 h . I n Fig . 9. 3 th e dat a ar e compare d wit hthos e

20 3 obtaine d fro

m Pb(NO-) 2 inhalations . Th e compariso ni s therefor e betwee nth e mos t rapi d lun g uptak e wit hth e lowes t (an d probabl y

slowest ) typ e o f gu t uptake . I t wa s no t possibl e t o mak e a n accurat e absolut e compariso n(i.e . i n term s o f 20 3 Ycountin g rat e pe r uC i Pb ) becaus e th e need t o shiel d th e detecto r fro m th e relativel y

massiv e amoun t o f Pbi n th e subject' 6 gu t affecte d th e countin g efficiency, bu t a t th e pea k (a t 2 4 hours ) th e observe d specifi c countin g rate s agree d t o withi n20% . 9.4. 3 Excretio n 

### Som e referenc e t o earl y excretio n followin g ingestio n has been mad e i n Sectio n 8 . Atalate rperio d (5- 7 days pos tintake ) th e mea n leve l o f

P b i n urine , expresse d a s apercentag e o f uptake , wa

s 1.0 8 1 0.08 % (S.E. ) pe rda y ( 4 subjects ) whe

n fastin g a tintak e an d 0.96 % pe rda

y ( tsubject ) fo rintak e wit h food . Thi s compare s wit h 0.83, 1 0.03 % pe rda y followin g salin e injection . Th e feca l excretio n rat e wa s 0.8 6 1 0.14 % pe rda

y ( 3 subjects ) compare d wit h

- . 0.4 1 1 0.05 % pe rda y followin g injection . Thi s suggest s tha teve n afte r6 day s ther e stil l ma

y b e som e residua l passag e o f

non-absorbe d P

b fro m th e gut . I f s o th e associate d erro rwil l b e quit e smal l becaus e a n exces s o f

0.4 % o f uptake pe rda

y correspond s t o amea n valu e o

T 0.08 % o

T intak e pe rda

y (assumin g 20 % uptake ) fo ralimite d period . I n fou rcase s acomplete collectio n o f urin e an

d fece s wa

s undertaken , an

d a t7 day s pos tintake , th e maximu m quantit y o f

P b no taccounte d fo rb

y excretio n an

d whole bod

y countin g wa

s 5.3 % (mea

n valu e -1.6%) . 9. 5 Summary

- o f result s o

T ingestio n experiments Uptak e o f lea d fro

m th e gu ti s affecte d both b y th e chemica l for

m o f th e lea d an d b y th e presenc e o f

foo d i n th e stomach . Both efTect s ar e importan tan d mus t b e considere d agains tabackgroun d o T marke d an d consisten tsubject-to-subjec tvaria tion . I tappears probabl e fro m thi s wor

k tha tth e effectiv e mea n percentag e uptak e fo rhealth y male s lie s i n th e range 13 % t o 18%

. Onc e th e lea d i s absorbe d int o th e syste m i tbehave s essentiall y a s tha tderive d fro m injectio n o rinhalatio n excep tfo r a n initia l dela y i n uptake o f afe w hours whic

h i s greates tfo rinsolubl e lea d i n th e presenc e o f

food .

-104 -TABL E 9. 1 20 3 Percentag e uptak e o T P bTro m th e gu t P. 7

Subjec t

AC C MJ H AC W DHF A D N KF B

Mea n S.D . S.E . Percentag e uptak e Tro m the gu t Fasting PbCl 2 5 4 4 0 6 0 2 8 6 5 2 4
4 5 1 7 7 Pb

S 2 6 2 1 3 2 9 2 0
1 2 1 0 4 Wit h PbCl 2 1 1 6 6 4 1 1 5
7 3 1 food Pb S 8 5 7 3 8 5
6 2 1 Mea n

2 5 13 2 2 1 0 2 3 1 4
1 8 6 3 Fasting Food
PbCl 2 4. 9 6. 7 10. 0 7. 0 5. 9 4. 6
6. 5 1. 9 0. 8 ratio .

Pb S 3. 3 0. 3 1. 9 0. 5 1. 1 4. 0
1. 9 1. 9 0. 8

TABL E 9. 2 Percentag e uptak e o T lead Tro m th e gut : compariso n o T publishe d dat a
' Autho r

Wetheril l e t al . (1975 )

Presen t wor k

Blak e (1976 )

Presen t wor k Percentag e uptak e Tro m gu t Wit hToo

d

— 9. 5 (3 )
6 (6 ) 7 (6 ) Fastin g 3 5 (3 ) 3 4 (3 )
1 2 (6 ) 4 5 (6 )

2 1 (11 )

2 0 (1 ) Lea

d compound s use d

Pb S Pb(N0 3 ) 2 Pb S PbCl 2
PbCl , betwee n meal s

« i I I i t
(Figure s i n bracket s ar e th e numbe r o T observations )

-105 -I

i 

### (a ) TABL E 9. 3 20 3 Th e hierarch

y o T subject s i nP bIngestio nexperiment s (b )

Pos i tio

n i n hierarch

y

1
2
3
4
5
6 Fasting/wit hfoo d considere d separatel y PbCl 2 Fas t
D N
AC W
AC C
MJ H
DHF A
KF B Foo

d

D N
AC C
AC W
MJ H
KF B
DHFA Pb

S Fas t
ACC
KF B
AC W
D N
DHF A
MJ H Food

AC C
D N
AC W
MJ H
KF B
DHF A Fasting/wit hfoo d considere d togethe r
PbCl 2
D N
ACC
AC W •

MJ H
DHFA I
KF B Pb

S
AC C
D N
AC W
KF B t 1

MJ H
DHF A 

### (c )

Mea n position i n hierarchie s unde r (a ) Subjec t
AC C
D N
AC W
MJ H
KF B
DHFA Mea n

1.7 5
2.0 0
2.7 5
4.2 5
4.5 0
5.7 5 ± S.E .

0.4 8
0.7 1
0.2 5
0.2 5
1.3 6
0.2 5

(Bracket s indicat e clos e grouping )P. 9

TABL E 9. 4 20 3 Percentag e uptak e i n gu to T Pb-labelle d exhaus t aerosol s

Subjec t

AC C MJ H AC W
DHF A D N 

### 1

Clea n exhaus t 6 9

- 5 1 1 1

- 197 7

r astin g Carbonaceou s exhaus taeroso l 3 5 1 6

- 4 0

- 197 3

Betwee n meal s UnclassiTie d exhaus taeroso l 8 9

-

- 1 6

TABL E 9. 5 Hair-llT e i n bloo d o T P b following ingestio n compare d wit h value s following salin e injectio n

Subjec t

MJ H

D N

AC C

Mea n HalT-liT e d
13. 5 14. 4 22. 3

10. 5 15. 3

15. 4 t 6. 0 S.D . 2. 7 S.E . Salin e injectio n

halT-liT e d 14. 9 (1974 ) 17. 4 (1977 ) 22. 0 (1974 ) 20. 9 (1977 ) 23. 2 (1977 ) 13. 9 (1974 ) 15. 3 (1977 ) 15. 7 (1977 )

-107 -P.1 0

X 

## PbCt 2 

## Pb S

c ti l o i n

a > o o . o > o > o c a > u k . c > 0 .



### 2345678 9 1 0 Percentag e uptak e wit h foo d A.ERE . R9198 . FIG . 9.1 . PERCENTAG E UPTAK E FRO M TH E GU TO F 20 3 PbC! 2 

### TAKE N WIT H AN D WITHOU TACCOMPANYIN G FOO D -108 -I 

## § O f



### E O 

### > o o

o SI

J 3 0 . 

### m o C M a > JO t . o </ ) x > o

Ot at 

### o c a > o i

_ o > C L 

### 10 0

1 0 - PKH O 

### Injectio n

SUBJEC TAC C

JOJLA 10 0 1 1 0 1 0 Elapse d hour s A ER E R919 8 FI G 9 2 VARIATION S O F LEVE L O

F 203 

### P b I N WHOL E BLOO D FOR VARIOU S MOOE S OF INTAKE .P.1 2

l/ l 

# z o

<



# o z < 

# z o

UJ 

# o z> — 

### o 

## £ o z T J — O

_ | U J 

## o u. i n 

## o

(M7 3 »D ) 

## s6a | ui AI;A!)3 D 

## >)Dd d j o e6o)ueDje d C v O O C M 

## c i o i O 

## u. C O 

### o > 

### e n o r u i cc u i <

-110 -P.1 3

10 . Synthesi s o T AER E an d othe r result s 10. 1 Introductio n I nthi s sectio npublishe dstudie s o n th e uptake , distribution , retentio nan d excretio no T lea dar e evaluate dand relate dt o th e Tinding s o T th e Harwel l work . Also , th e availabl e evidenc e i s examine do n sam e issue s whic hcoul dno t b e studie d directly , suc ha s the respons e o T children' s bloo dleadt o leadi n ai r and the relativ e intake s Tro m air , wate r and diet . I t i s almos t impossibl e t o review th e extensive , and no t wholl y consistent , literatur e o n huma nuptak e o r lea dwithou t introducin g som e elemen t o r persona l choic e o r discrimination . Th e objectiv e o T thi s sectio ni s t o examin e ho w Ta r a consisten t pictur e ca n b e buil t u p whic hencompasse s mos t o T th e majo r publishe d contributions . Th e Tollowing abbreviation s ar e used : Pb A Pb B Pb U Pb W APb B A I til G U F

f g " •gh "

f s "



### a b Concentratio no T leadi n ai r (ug/ m ) Concentratio no T leadi n bloo d(ug/iO O g ) Concentratio no T leadi n urin e (ug/l ) Concentratio no r leadi n wate r (ug/l ) Increas e i n Pb B du e t o exposur e t o PbA o r Pb W Lea ddeposite di n lung (ug/d ) Lea dingeste di n rood an d drink (ug/d ) Increas e i n I du e t o ora l dose s Lea dtake nu p Tro

m gu t (ug/d ) Lea dexcrete di n urin e (ug/d ) Lea dexcrete di n Tece s (ug/d ) Endogenou s Teca l excretio n(ug/d ) Lea dstore d(ug/d ) G/ I Tractiona l uptak e Tro m gu t Fractio no T uptak e fro m gu t whic hi s transferre dt o re d cell s S/ Gfractio no f uptak e whic hi s store d f f fractio no f ingeste dleadwhic hi s store d Mas s o f bloo d(kg ) Fractiona l depositio n i n lun g Fractio n o f

lun g burde n transTerre d t o re d cell s Biologica l halT-liT e i n bloo d (days ) Th e publishe d inTormatio n i s o rthre e mai n types :

-111 -• r'rT-.uri P.1 4

(a ) Populatio nsurvey s i n whic hPb B o f individual s or group s O T p ; • «on s ar e correlate dwit hlocall y measure dPbA . (b ) Experiment s i n whic hvolunteer s ar e expose dt o artificiall y enhance dPti

A To r a numbe r o T hour s pe r day ove r lon g period s an d th e resultin g varia tion s i n PbB measured . Alternatively , Pb A ma y b e eliminate db

y keepin g volunteer s i n clea nai r environment s and th e consequen t declin e i n Pb B observed . (c ) Studie s or th e lea dbalanc e o T individuals , i n whic hth e contribution s o T lea di n roodand drink ar e assessed , and th e contributio no r Pb A estimated . Th e dirTicult y

wit hpopulatio nsurvey s i s tha t o r uncontrolle dvariables . Numerou s survey s hav e show ncorrelation s o T PbB and Pb A i n diTTeren t area s o r cities , o r dependin g o n distanc e Tro m some know

nlea dsources , bu t very oTte nther e i s th e possibilit y

tha t Tactor s suc ha s housing , occupation , dietar y an d socia l habit s ma y als o contribut e t o th e observe dgradient s i n PbB . A compariso no r th e PhBAb A 20 3 relatio ndeduce dTro m wor k wit hP bwit hth e result s o T tw o majo r populatio nsurvey s wa s mad e i n th e previou s pape r (Chamberlai ne t al . 1975) . Som e Turthe r reference s t o thi s typ e o T survey ar e give ni n thi s paper , an d a ful l revie w ha s bee npublishe d b y Bridbor d(1977) . I ti s considere d worthwhil e t o re-examin e some o T th e mai n publishe d work o T type s (b ) and (c ) abov e i n th e ligh to T th e informatio n obtaine d wit h i s don e i n relatio n to : 203 , Pb . Thi s
(i ) Estimate s o T Tractiona l uptak e o T leadi n ai r an d diet , an d transTe r an d retentio ni n blood , skeleto nan d othe r organs . (ii ) Relationshi pbetwee nPb B an d PbA . (iii ) Relativ e contribution s o T lea di n air , roodan d wate r t o tota l intake . 10. 2 Uptak e an

d storag e o T lea di n Kehoe' s experiment s Keho e (196lb ) gav e dail y ora l dose s o T P bt o subjects , analyse ddiet , urin e an d feces , an d dre

w u p balance s o f ingeste dand excrete dlea dTro m whic hth e amoun t store d wa s estimated . Th e result s show

ni n Fig . 1 1 o T Keho e (1961b ) ar e tabulate di n Tabl e 10.1 . Subject s SW , M R an

d EB , wh o receive drespectivel y 0.3 , 1 an d 2 n g o T P bdaily , store d betwee n0.0 5 and 0.0 8 o T th e tota l lea dingeste d(ora l dos e plu s leadi ndiet ) ove r th e experimenta l period . Subjec t I F wh o receive d3 mg/ d fo r 11 2 d , store dn o les s tha n0.1 5 (15$ ) o f hi s tota l ingeste dlead . I T i t i s assume dtha t th e subject s wer e i n balanc e a s regard s norma l dietar y lead wit hequa l amount s transferre dt o an d Tro m storage , and th e storag e durin g th e experi menta l perio drelate dsolel y t o th e ora l dose , the nthi s represent s a Tractio nT s o T th e dos e equa l t o 0.0 8 t o 0.0 9 Torsubject s SW , M Ran d E B an d 0.1 6 TorIF . I T f i s th e fractiona l uptak e i n gut , an d f th e fractio n o f

th e uptak e trans ferre d t o storage , the n Kehoe' s result s giv e ameasur e o f th e produc tf

= f r. s g g s -112 -P.1 5

A s wil l b e th e rati o : ;7W

n , T an

d f ca n b e deduce dseparatel y I T an assumptio ni s mad e abou t ©© ^ o r endogenou s Teca l t o urinar y excretion . BeTor e doin g that , i t I s wort hnotin g tha t value s o r f o f abou t 0.0 8 ar e consisten t wit hf

_abou t 0.1 6 (i.e . s g \S% uptak e fro

m gut ) and f

abou t0. 5 ( i.e . 50 $ o T absorbe d lea d transTerre d t o g s I T T i s les s tha n0.5 , the nT mus t b e mor e tha n0.16 , and vic e versa , g s g storage) . Moreover , Kehoe' s estimate s o r store dlea dreTe r t o th e ne t storag e ove r th e exper i menta l period , whic hi n MR' s cas e wa s a s lon g a s 145 6 days . Fo r subject s M R an d EB , Keho e gav e a detaile danalysi s o r dail y intake , excre tio nand storag e o f lead , whic hi s reproduce di n th e uppe r par t o T Tabl e 10.2 . Keho e note dtha t To r bot hsubjects , the amoun t o T lea dstore dwa s o T th e sam e orde r a s th e amoun t excrete di n urine . I t wa s no t possibl e t o asses s th e endogenou s Teca l excre tio ndurin g the perio do T ora l dosing , sinc e i t wa s maske db y th e relativel y

large r amount s o T unabsorbe dleadexcrete di n Teces . By comparin g th e Teca l excretio no T th e subject s durin g th e follow-u pperiod s (als o show ni n Tabl e 10.2 ) wit hth e Teca l excretio no f th e sam e subject s befor e dosin g began , Keho e (196lb , Table s 2 2 and 23 ) obtaine destimate s (necessaril y approximate ) tha t subjec t EB' s endogenou s Teca l excretio nwa s abou t equa l t o hi s urinar y excretio nwherea s subjec t MR' s endogenou s Teca l excretio nwa s small . I T a Tigur e i s assume dTo r F AJ , th e tru e uptak e Tro m the gu t i n Kehoe' s sub ject s ca n b e deduced , assumption s I nthe lowe r par t o f Tabl e 10. 2 thi s i s don e wit hth e
(a ) F /\

J =0. 5 To

r bot hsubject s (thi s i s the mea nvalu e To r th e Harwel l
(b ) F e / U subjects) , 1 To r E B bu t F A j = 0 To r MR . O nassumptio n(a) , th e fractiona l uptake s Tro m gut , T , durin g the dosin g period , ar e 0.1 4 (MR ) an d 0.1 5 (EB) . O n assumptio n(b ) the y ar e 0.1 1 (MR ) an d 0.1 8 (EB) . Th e Traction , f , o T th e uptak e whic har e store dar e 0.4 0 an d 0.5 0 o n the g s Tirs tassumptio n and 0.4 9 an d 0.4 3 on th e second . Thu s Kehoe' s ver y length y and detaile d analysi s o T th e lea d balanc e o T thes e subject s implie s tha tbetwee n 0.1 1 and 0.1 8 o T ora l dose s o

T lea d wer e absorbed , an d 0. 4 t o 0. 5 o

T th e absorbe d dos e wa s store d To

rperiod s oT month s t o years , presumabl y mostl y i n bone . I n Tabl e 10. 3 asimila rcalculatio n i s don e TorKehoe' s subjec tPC , who wa s expose d Tor37. 5 hour s pe rweek Tor8 8 week s t o a n aeroso l o T 15 0 ug/ m o T lea d oxid e i n a n experixnenta l chamber . Keho e estimate d tha tth e retentio n oT th e aeroso l i n th e lun g wa s X% and tha tth e tota l amountoT lea d deposite d i n th e lun g wa s 9 8 mg . Thi s i s consisten twit h a1 0 1/mi n ventilatio n rat e i n th e lung . A s th e aeroso l wa g sub-micro n i n size , i ti s assume d tha tth e depositio n wa s i n th e pulmonary region , and tha tal l th e retaine d lea d was take n u p int o th e circulation , wit h negligibl e amounts removed by ciliar y actio n and swallowed . Th e analysi s o rth e dat aTro m subjec tPC , wit h th e assumptio n tha tF A) c 0.5 , give s 0.19 , 0.1 2 and 0.2 1 Tractiona l uptak e rro m gu ti n th e preliminary , experimenta l

-113 -P.1 6

and follow-u p period s respectively . Durin g th e 61 6 day s o rth e ev.\ 2.\Litiental period , i ti s estimate d tha tF C too k u p 16. 5 m

g P b Tro m hi s gut , making , 'M.th v ,h e 9 8 m g retaine d i n th e lung , atota l intak e o T 114. 5 mg . The ne tamountj-ci-e d wa s 4 7 mg , \ j whic h i s 0.4 1 o rth e tota l uptak e o r0.4 8 o T th e amountretaine d i n th e lung . Th e conclusio n Tro

m thi s re-examinatio n o rKehoe' s result s i s tha tthe y ar e 20 3 consisten twit h th e hypotheses , derive d Tro m wor k wit h P

b (a ) Uptak e fro

m gu ti s abou t15-20 $ o f ingeste d Pb , \ (b ) Abou thai rth e uptak e become s Tixe d i n bloo d and i s excrete d wit h a

halT-liT e o

T abou t2 0 days , \ (c ) Mos to rth e othe rhai ri s store d i n bon e o relsewher e wit h ahalT-liT e

o T orde ryears . 10. 3 Uptak e an

d storag e o

T lea d i n UCL

A experiment s Rabinowit z an d hi s colleague s a tUniversit y o rCaliTornia , Lo s Angele s (UCLA) , 20 4 di d anotabl e serie s o T experiment s i n whic h th e stabl e isotop e P b wa s give n t o subject s orall y (Rabinowitz , 1974 ; Rabinowit z e tal . 1973 , 1976a , b , 1977 ; Wetherill , e tal . 1975) . I n som e experiment s th e subject s wer e Te d alow-lea d die t durin g th e experimenta l period , s o tha tth e tota l lea d intak e (die tplu s ora l dose ) 20 4 was unchanged . Mas s spectrometr y was use d t o determin e th e amounto T P b i n bloo d an d excreta . Also , i n tw o subjects , bon e biops y sample s wer e take n Tro m th e ilia c cres tt o measur e th e uptak e b y bone . Th e tota l lea d conten to f biologica l sample s wa s als o determine d b y mas s spectro 20 8 metry , usin g th e isotop e dilutio n metho d i n whic h aspik e o f P b wa 6 adde d t o th e samples . Thi s metho d i s independen to f th e yiel d o rth e chemica l analysi s step . A ver y hig h degre e o f accurac y wa s obtained . Replicat e analyse s o f homogenise d feca l sample s agree d t o withi n 2 $ (Rabinowit z e tal . 1977) . Sequentia l samplin g o T bloo d ever y Te

w day s gav e curve s whic h sugges trando m error s o rorde r1# . Thi s hig h degre e o rreproducibilit y enable d Rabinowit z e tal . t o observ e th e eTTec to n bloo d lea d oT puttin g asubjec ti n aclean-ai rroom . Rabinowit z e tal . interprete d thei rresult s i n term s o T athree-compartmen t •odel , wit h th e firs tcompartmen tblood , th e secon d sor ttissu e an d th e thir d bone . Ther e ar e tw o diTTerence s betwee n th e UCL A an d Harwel l models . I n ou rview , bloo d plasm aand re d cell s mus treall y b e considere d a s tw o compartments . The initia l uptak e o rP

b Tro m lun g o rgu ti s t o plasma , wher e i ti s rapidl y distribute d t o re d cells , bon e and othe rstorag e sites . Whil e ther e ma y wel l b e transTe rt o an d Tr o betwee n blood , bon e an d othe rorgan s a tlate rtimes , th e initia l distributio n appear s t o b e achieve d withi n th e Tirs tTe w hours . I n th e UCL A model , P

b enterin g bloo d ha s amea n residenc e tim e ther e o T abou t3

6 days , an d i s the n excrete d i n urine , trans ferre d t o bone , o rtransferre d t o asecon d soT ttissu e pool . I n th e secon d pool , th e residenc e tim e i s abou t4 0 days . Endogenou s Teca l excretio n (i n bile , gastri c secretion s and pancreati c secretions ) take s plac e Tro m th e secon d poo l only , and consequentl y i s delaye d b y abou t4 0 day s relativ e t o urinar y excretions .

-114 -P.1 7

The metho do T measurin g s ogenou s Teca l excretio nb y th e UCL A

worker s durin g 2D 4 th e perio do r dosin g wit hPc , wa s a s Tollow s (Rabinowitz , 1974 , p.10) : "Alimen tar y secretio ncollection s wer e mad e wit ha dua l rubbe r tub e passe dorall y and locatedwit ha Tluoroscope . A sligh t vacuu

m wa s applied . Basa l restin g gastri c collection s wer e made , the ncholecystokini nwa s use dt o induc e bilar y flowagc , and 20 4 late r secreti nstimulate dpancreati c Tlui dproduction" . Th e P band tota l lea d concentration s wer e measure di n th e sample s s o obtained , and th e dail y outpu t derive dusin g standar destimate s o T volume o r bil e etc . produce deac hda y (Rabinowitz , 1974 , Tabl e VIII) . 

### 20 4 During th e Tollow-up period s arte rth e ora l dose s o T P b wer e discontinue d 20 4 Pbi n Tece s coul db e attribute dunambiguousl y t o endogenou s excretion . Th e result s ( Rabinowit z e t al . 1976b ) ar e show ni n Tabl e 10.4 . Th e mea nendogenou s Teca l clearanc e ( F /PbB) , wa s 2. 5 g/h » compare dwit h1. 8 gA i i n th e Harwel l subject s receivin g P bb

y injectio n(Tabl e 8.4) . Th e diTTerenc e betwee nthe Harwel l an d UCLA Tinding s i s i n th e tim e o r onse t o T endogenou s Teca l excretion . Harwel l wor k wit hPb , an d als o wor k wit hP b 21 2 o r P bo n baboon s (Cohen , 1970) , dog s (Lloy de t al . 1975 ) and rat s (Morga ne t al . 1977 ) indicate s tha t endogenou s Teca l excretio ni s establishe dalmos t simultaneousl y wit hurinar y

excretion , th e onl y apparen t delay

bein g du e t o th e tim e take nTor passag e o r Teca l matter . Thi s als o appear s Tro m th e experiment s o T Harriso ne t al . (1966) , an

d Harriso nan

d Sutto n(1967) , i n whichCa , Sr , B a and R a wer e injecte dint o huma nsubjects . A nattemp t i s mad e her e t o asses s the UCL A dat a independentl y

o r th e UCL A model , and als o t o se e th e consequence s o T applyin g th e Harwel l mode l t o th e UCL A data . 20 4 I nTabl e 10. 5 th e uptake , excretio nand storag e o T P bi n the UCL A subjects , A , B and D are analyse di n th e same wa y a s To r Kehoe' s subject s i n Table s 10. 2 an d 3 . Th e Tigure s i n th e uppe r par t o r Tabl e 10. 5 ar e derive ddirectl y Tro m th e result s give ni n th e UCL A

paper s wit hn o additiona l assumptions . Th e amount s o T store dlea d calculate dTro

m th e balanc e betwee ningestio nand excretio n(63 0 u g To r A , 63 0 u g 20 4 To r B ) agre e wel l wit hRabinowit z e t aL' s estimate s o T th e skeleta l P ba t th e time s o T th e bon e biopsie s (namel y 70 2 u g To r A , 67 4 u g To r B) , assumin g tha t th e 20 4 concentration s o T P bi n trabecula r an d cortica l bon e o T th e skeleton s generall y wer e th e sam

e a s th e concentration s Toundi n th e trabecula r an d cortica l fractio no T 20 4 th e biops y

sample . Th e amount s o T P bstore drepresente dbetwee n0.0 3 and 0.0 4 o T th e tota l ingested , whic hi s lowe r tha nToun dTo r Kehoe' s subject s (0.05 6 - 0.152) . T o deduc e th e Tractiona l uptak e Tro m th e gu t i n th e lowe r par t o r Tabl e 10.5 , a nestimat e i s mad e o T th e endogenou s Teca l excretio ndurin g th e perio do T dosin g wit h 

### 20 4 P b b y referenc e t o th e datao rTable 10.4 . Thi s give s slightl y highe restimate s o rF g

### than i n Rabinowit z e taL' s ow

n analysi s butth e eTTec to n th e estimate s o

T uptak e Tro m th e gu ti s small . I n Rabinowitz's analysis , th e value s o rT ar e 0.085 , 0.06 5 an d 0.10 9 To r subject s A , B an d D .

-115 -P.1 8

Returnin g t o Tabl e 10.5 , th e fraction s o rth e uptak e whic h ar e store d ar e 0.4 , 0. 5 an d 0.4 , i n goo d agreemen twit h th e result s derive d i n Table s 10. 2 an d 10. 3 Tro

m Kehoe' s results , an d wit h th e concep ttha tmos to T th e lea d take n u p from lun g o r gu twhic h doe s no tbecam e attache d t o re d cell s i s store d i n bone . The estimate s o f

uptak e o f

204 P b ca n b e relate d t o Rabinowit z e tal' s (1976b ) 20 4 dat ao n P

b i n bloo d o f

thes e subjects . Th e measurement s fo rsubject s A , B and D whic h sho

w excellen tinterna l consistency , ar e reproduce d i n Fig . 10.1 . I f i ti s assume d tha t555

6 o rth e uptak e become s attache d t o re d cell s (Tabl e 7.2) , an d tha t th e eliminatio n o rP b Tro m bloo d ca n b e describe d i n term s o T arat e constan tX , the n 20 4 th e predicte d P

b i n bloo d i n unit s oT ug/lO O g i s 204 D . „ 0.05 5 G , , . w . Pb B = — ^ ( 1 - exp-Xt ) wher e G = rat e o T uptak e Tro

m gu t(ug/d ) M = bloo d mas s (kg ) X = rat e constan tTo rremova l fro

m bloo d (d ~ ) 1/ X = mea

n lif e i n bloo d (d ) 0.693 A = half-liT e i n bloo d (Tj . Fro m th e result s o f

th e UCL

A work , value s oT rat e constant , mea n liTe , o r hair-liT e o rP

b i n bloo d ca n b e deduce d i n thre e ways : (a ) b y Tittin g curve s o T th e Tor

m a[ l - exp(-Xt) ] t o th e incremen tphase s 20 4 o T P b i n blood , (b ) b y Tittin g curve s o rth e Tor m a . exp(-Xt ) t o th e decremen tphase s followin g th e en d o f

th e dosin g perio d (Fig . 10.2) , (c ) b y takin g value s o f G fro m Tabl e 10. 5 an d findin g value s o f X suc h tha t th e equilibriu m (plateau ) valu e o f Pb B a s measure d experimentall y (Fig . 10.1 ) i s equa l t o 0.05 5 G X - 1 M~' . Method s (a ) an d (b ) depen d onl y o n th e shap e o f th e curve s i n Fig . 10.1 . 20 4 Metho d (c ) depend s o n th e concentratio n o T P b i n th e subject' s bloo d a tequili 20 4 brium . A correctio n mus tb e applie d t o th e recorde d maximu m valu e o T P

b t o allo w fo rafurthe rsligh tincreas e t o b e expecte d I T th e dail y dosin g had continue d unti l equilibriu m wa s obtained . Thi s correctio n amounts t o 5$ , S% and 19 $ To rsubject s A , B and D respectively . Th e result s fo rth e thre e method s whic h ar e essentiall y independen tar e give n i n Tabl e 10.6 . Estimate s b y metho d (b ) onl y ar e als o give n 20 4 fo rsubject s C and E , wh o receive d P

b fo ron e (C ) an d tw o (E ) shor tperiods . Th e estimate s o f

mea n lif e obtaine d b y Rabinowit z e tal . (1976b ) fro m thei rmode l ar e als o shown i n Tabl e 10.6 . 20 4 A s show n i n Fig . 10.1 , th e P b i n bloo d o f

th e UCL

A subject s A an d B approache d a n apparen tplatea u beTor e th e en d oT th e perio d o T dosing . Fo rsubjec t D , th e halT-liT e i n bloo d wa s longe r(Tabl e 10.6 ) and aplatea u had apparentl y no t bee n reache d whe

n dosin g cease d a t8 2 d . I tca n b e estimate d tha tth e tru e platea u 20 4 P b concentration s wer e 7.6 , 4. 8 and 5. 4 ug/iO 0 g fo rth e thre e subjects . However
-116 -P.1 9
204 th e rati o o

T Pb B t o tota l Pb

B a tth e platea u wa

s no tthe n equa l t o th e rati o o T 2W P b ora l dos e t o th e tota l P b i n die ta s show

n i n Tabl e 10.7 . Fro m thes e -/..suits , Rabinowit

z conclude d tha tonl y abou t55 $ o T Pb B wa s derive d fro

m curren tdietar y uptake , th e remaindercomin g fro m inhale d lea d an

d fro m rcsorbe d skeleta l lead . A t he clearl y recognised , thi s conclusio n depends o n th e percentag e uptake fro m th e gut 20 4 o f th e P

b ingeste d a s a dail y dos e (wit h food ) an d o f th e dietar y lea d bein g identical . I t i s possibl e t o juggl e Rabinowitz' s result s i n variou s ways , bu t i t seem s probabl e tha t a n appreciabl e Tractio n(perhap s 1/ 4 t o 1/3 ) o T th e Pb B i n middle-age d subject s i s derive dTro m resorbe dskeleta l lead . Suc ha belie T i s consisten t wit h the vie w tha t nearl y

hai r o T the P btake nu p Tro m gu t o r lun g goe s int o storag e mainl y i nth e skeleto n(Table s 10.2 , 10.3 , 10.5) . I f thi s rat e o f storag e continue dfo r a liTetime , wit hn o resorption , the nth e increas e o f skeleta l lea dwit hag e woul db e greate r tha ni s observe d(Sectio n10.8) . Th e UCL A stud y als o include dmeasurement s o f th e reductio no r bloo dleadwhe n subject s wer e kep t i n clean-ai r rooms . Subject s B , D andE spen t 40 , 2 5 an d4 0 day s respectivel y

i n Tiltere d ai r room s (Rabinowit z e t al . 1976b , 1977) . Th e interpreta tio nTo r subjec t B i s somewha t complicate dbecaus e change s i n th e dail y ora l dose s o T isotopically-separate dleadals o too k plac e durin g th e sam e perio dbu t ther e seem s littl e doub t tha t PbB o f subject s B an dE decline db y betwee n1. 5 an d2. 5 Ug/l0 0 g durin g 4 0 day s i n a clea nai r environment . Sinc e th e ambien t Pb A wa s probabl y

abou t / 3 2 ug/ m , thi s i s a s expecte dTra m othe r work . Th e detectio no T a Tal l o T thi s magnitud e i n individua l subject s wa s onl y Teasibl e becaus e o T th e ver y accurat e UCL A techniqu e To r measurin g PbB . Th e UCL A

worker s (Rabinowit z e t al . 1977 ) assesse dth e intak e o T P bb y th e respirator y

rout e b

y thre e method s (Tabl e 10.8) : (a ) b y a n overal l lea dbalance , i nwhic hinhale dintak e i s equate dt o dietar y minu s Teca l minu s urinar y lead , (b ) b y assessin g the contributio no T dietary lea dby

th e trace r techniqu e an d attributin g th e remainde r t o inhale dlea d(i t i s no t clea r whethe r a contributio nTro

m resorbe dbon e lea dwa s included) , (c ) b y measurin g th

e respons e o T PbB t o th e clea nai r environment . Th e result s obtaine db y metho d(c ) ar e possibl y th e mos t accurate . Th e mea n intak e To r subject s B , D an dE b y thi s method , 1 3 Mg/d , compare s wit h1 5 ug/d , th e valu e expecte di T th e ai r concentratio ni s 2 Ug/ m , breathin g rat e 1 5 m / d and depositio ni n lun g 50$ . 10. 4 Elevatio no T bloo dleadi n experimenta l exposur e o T subject s t o Pb A (a ) Kehoe' s subject s Keho e (1961b , Fig . 21) , give s th e averag e concentratio no T leadi n bloo d o T subjec t P C i n eac hsuccessiv e periodo r 2 8 days . Durin g th e 53 2 day preliminar y

perio dberor e PC' s exposur e t o Pb A i n th e experimenta l chambe r

-117 -P.2 0
began , hi s Pb

B average d 25. 7 ug/lO O g . Th e concentratio n i n th e chambe rwa s 12 0 ug/ m , an d P

C spen t37. 5 hrs/wee k i n it , s o th e equivalen t24-hou rPbA , B E show n i n Tabl e 10. 9 wa

s 33. 5 ug/

m . Whe

n exposur e began , FC' s Pb B ros e t o 4 2 ug/10 0 g withi n 56 days , bu tthereafte rther e was n o systemati c increase , thoug h ther e wer e fluctuation s o f ±1 0 ug/l0 0 g whic h ma y hav e bee n cause d b y change s i n dietar y lea d o rfractiona l uptak e fro m th e gu ta s wel l a s b y factor s relativ e t o inhalation . Th e diTTerenc e betwee n th e platea u PbB , average d o n th e las t50 4 day s o

T th e tota l exposur e perio d o T 61 6 days , and th e averag e pre-exposur e Pb

B i s terme d th e elevatio n APb B an d To

rP C thi s work s ou ta t 16. 6 ug/10 0 g . Th

e rati o APbB/Pb

A i s th e Tacto ra , whic h i n thi s cas e i s 0.5 . Keho e als o give s th e dail y urinar y excretio n U . The rati o U/PbB , i s expresse d conventionall y i n th e unit s ml/ h (i.e . th e amoun to rP b excrete d i n urin e pe rhou rexpresse d a s th e equivalen tbloo d volume) . A s a n attemp ti s Bad e i n thi s pape rt o standardis e a s mas s unit s rathe rtha n volumetri c units , rena l clearance s ar e give n i n Tabl e 10. 9 i n g/h . Th e rena l clearanc e rat e ros e Tro m 3. 7 g/ h pre-exposur e t o 7. 6 g/ h durin g exposure , whic h mean s tha tU increase d mor

e tha n proportionatel y t o th e increas e i n PbB . Thi s i s commonl y foun d i n industria l exposur e t o lead , and show s tha texcretio n i s speede d up , presumabl y wit h an associate d reductio n i n th e mea n lir e i n th e blood . I n anothe rserie s o f experiments , Kehoe (1966 ) expose d subject s L D an d J S t o th e same ai rconcentratio n (15 0 Ug/ m ) Toravaryin g numbe ro T hour s pe r day . Durin g 11 2 days , the y wer e i n th e chambe rTo r10. 5 hours/week , the n durin g anothe r11 2 day s To r2 1 hours/week , the n 11 2 day s a t31. 5 hours/wee k and Tinall y 11 2 day s a t4 2 hours/week . Thu s th e 24-hour s equivalen tPb A wa s 9.4 , 18.8 , 28. 2 and 37. 5 ug/ m . Kehoe tabulate s th e subjects ' Pb B a t28-da y intervals' , eac h valu e bein g th e mea n o f 8 determinations . T o allo w To r adjustmen tt o th e increase d PbA , onl y th e Pb B Torth e las t2 8 day s i n eac h 112-da y perio d ha s bee n use d t o calculat e APb B (averag e o

T L D an d JS ) i n Tabl e 10.9 . Keho e the n di d afurthe rserie s (subject s N Kan d SS ) wit h th e same syste m o f 11 2 day s exposur e fo rvaryin g hour s pe rweek bu twit h th e concentratio n i n th e chambe rreduce d t o 1 0 Mg/ m . Thi s wa s evidentl y designe d t o tes twhethe r exposur e a tambien ta s distinc tfro m industria l atmosphere s o f Pb A woul d giv e appreciabl e elevatio n o f PbB . Th

e 24-hou requivalen tPb A i n thes e experiment s increase d stepwis e from 0.6 2 t o 4.3 7 Ug/ m (Tabl e 10.9) . Kehoe' s (1966 ) ow n assessmen to f

th e result s was a s follows : "Ther e appeare d t o b e asligh t increas e i n th e outpu to f lea d i n th e urin e and i n th e concentratio n o f lea d i n th e bloo d o f

bot h subject s a s th e experimen tprogressed . Th e increas e was irregular , lat e i n puttin g i n it s appearanc e i n th e cas e o f subjec tSS , an d o f suc h sligh tproportio n i n bot h instances , a s t o b e o f dubiou s significance . Th e dat arevea l trends , however , whic h woul d seem t o b e surTicientl y persisten t t o b e valid" .

-118 -P.2 1

I n Kehoe' s paper , h e mention s tha taserie s o rpre-exposur e measurement s wer e don e lastin g 2 9 week s (NK ) an d 1 9 week s (SS) , bu tth e result s o T thes e ar e no tgive n i n th e paper , wherea s th e result s on th e simila rpre-exposur e 6erie s on L

D an d S S ar e given . However , Goldsmit h and Hexte r(1967) , who use d Kehoe' s results , giv e th e mea n pre-exposur e Pb

B To rN Kan d SS , presumabl y havin g hB

d acces s t o th e origina l data , and thes e Tigure s ar e shown i n Tabl e 10.9 . Takin g th e Tina l 2 8 day s o T eac h 112-da y experimenta l perio d a s th e plateau , APb

B i s calculate d o n th e increas e abov e th e pre-exposur e Tigure . As ther e ar e onl y tw o subjects , and eTrectivel y on e dat apoin tTo reac h sub jec tTo reac h Pb

A valu e (Kehoe' s dat apoint s ar e howeve rmean s oT eigh tread ings) , th e APb

B an d avalue s show considerabl e scatte r(th e scatte ri s reduce d slightly , and th e mea n aTorth e whol e serie s littl e altered , I T th e Tina l 56 day s o T eac h 112-da y perio d i s take n a s th e plateau , givin g 2 dat apoint s pe r subjec tpe rPb

A level) . I ti s doubtTu l i T th e variatio n o T o betwee n period s i n Kehoe' s experiments , o rth e dirrerenc e i n mea n result s betwee n th e serie s o n L D an d J S and tha to n N Kand SS , i s significant . Th e overal l mea

n aTro m Kehoe' s wor

k (1 2 determinations ) i s 1. 1 wit h standar d erro r0.15 . (b ) GrirTi n e taL' s subject s Kehoe' s metho d wa s t o mak e ver y complet e measurement s o n asmal l numbe r o T subjects . GrirTi n e tal . (1975 ) expose d large rnumbers o T volunteer s i n a roo m a tDannemora , N.Y. , wher e the y remained 2 3 hour s pe rday . No tal l th e volunteer s remaine d To rth e ful l ter m o f

th e experiment . I n Tabl e 10.9 , th e result s o rcohorts , eac h membe ro rwhic h remaine d Torth e sam e time , ar e analysed . As i n Kehoe' s experiments , th e lea d oxid e aeroso l was prepare d b y burnin g tetra-ethy l lea d i n propane . Th e particl e siz e wa s 0.0 5 t o 0. 1 urn . I n on e experimen tth e airborn e particulat e lea d concentratio n was 10. 9 ug/ m and i n anothe ri twa s 3. 2 ug/ m (th e correspondin g 24-hou requivalen tt o Pb A value s use d i n Tabl e 9 ar e 10. 4 an d 3. 1 ug/

m ) . Sample s take n wit h a n iodize d carbo n 'back-up ' Tilte rbehin d th e particulat e Tilte rindicate d th e presenc e o f an additiona l lea d component , equivalen tt o betwee n 1 0 an d 15 $ o rth e tota l amounto

T airborn e lea d i n th e chamber . Presumabl y thi s was unburn tTE L vapour . Pb B wa s measure d i n tw o weekl y sample s beTor e th e Dannemor asubject s entere d th e chamberan d a teithe rweekl y o rTortnightl y interval s thereaTter . Som e measurement s o rurinary ' lea d a s u g P b pe rg tota l solid s i n urin e ar e als o given . Usin g th e standar d man' s outpu to r6 0 g/ d solid s i n urin e (ICRP , 1975) , U i n ug/ d i s give n i n Tabl e 10.9 . Th e averag e rena l clearanc e i n GriTTi n e taL' s subject s i s 4. 5 g/h , whic h agree s wel l wit h th e Harwel l P b value . GriTTi n e tal . note d tha tth e mea n Pb B oT thei rsubject s increase d a tth e star to T th e exposure , bu tarte rabou t1 2 week s ther e was n o Turthe rincrease . I n Tabl e 10.9 , Pb

B from 1 2 week s onward ha s bee n use d t o calculat e APb B an d c u Th e mea n valu e o f

ai s 1.5 5 ug/10 0 g pe rugA > . Thi s makes^n o allowanc e fo r an y possibl e contributio n t o Pb B Tro m th e 1 0 o r15 $ o

T th e lea d i n th e atmo spher e whic h penetrate d th e particulat e Tilter . 

# r

-119 -

### A n alternativ e metho

d o T analysi s o

T th e Dannemor

asubject s i s show

n i n Fig . 10.3 . Her

e th e APb

B To reac h subjec ta teach bloo d samplin g i s worke d ou tb y referenc e t o tha tsubject' s pre-exposur e PbB , an d th e result s ar e averaged . Curves hav e been fitte d o f

th e for m B(t ) = B ( I - exp-Xt ) wher e B(t ) i s th e elevatio n o f th e subject' s Pb

B above th e pre-exposur e level , B i s th e platea u elevatio n valu e an d X th e tim e constant . Th e bes tfi ti s 0 0 

### - 1 obtaine d wit h th e value s o f B an d X give n i n Tabl e 10.10 . Th e mea n liT e X 0 0 

### 3 o rlea d i n bloo d deduce d Tro m thi s analysi s i s 4 1 day s (Pb A = 10. 4 ug/

m ) an d 3 7 day s (Pb

A = 3. 1 Mg/

m ) an d th e correspondin g T

. value s ar e 2 8 an

d 2 6 days . Thes e ar e longe rtha n Toun d i n th e Harwell wor

k (Tj ^ = 1

8 d ) bu tcomparabl e wit h th e UCL

A result s (Tabl e 10.6) . (c ) Tola' s subject s A simila ranalysi s o

T th e elevatio n o

T Pb B i n industria l workers i s show n i n Fig . 10.4 , base d o

n th e wor

k o T Tol ae tal . (1973 ) wh o measure

d Pb B i n 3 3 ne w entrant s t o alea d works . Th e averag e Pb

B beTor e startin g wor

k wa s 16. 5 ug/io o g . Arte rstartin g work, Pb B ros e t o aplatea u o

T 49. 0 Ug/i0 0 g arte r6 0 days . Th

e bes tTi tt o th e curv e o T APb B agains ttim e (Fig . 10.4 ) give s X = 0.07 2 days ' , T , = 1 0 d . Th

e variatio n o

T APb B with tim e i n Stui k an d Zielhuis' s (1975 ) subjects , wh o receive d dail y ora l dose s o T lea d (2 0 ug/k g bod y weigh tpe rday) als o indicate s ashorte rT ^ than Toun

d i n th e UCL

A o r Dannemor asubjects . 10. 5 Survey s o

T bloo d lea d versu s ai rlea d i n variou s region s Teppe ran d Levi n (1975 ) relate d th e bloo d lea d o T group s o

T wome n volunteer s i n 1 1 communities t o measurement s o T ai rlea d a tanumbe

ro T fixe d samplin g station s i n each area . Th

e correlatio n o

T Pb B wit h Pb

A wa s signiTican tonl y a tth e 10 $ level , butth e result s wer e no tinconsisten twit h th e hypothesi s tha tai s abou t unit y (Chamberlain e tal . 1975) . Th e result s o

T th e surve y o

T Aza re tal . (1975 ) wer e als o consisten twit h tha thypothesis . Tsuchiy ae t%1 . (1975 ) compare d Pb B i n policeme n fro

m variou s area s o

T Toky o wit h Pb

A measure

d i n thos e localities . Th e result s ar e show

n i n th e uppe

rpar to T Fig . 10.5 . Th e regressio n o

T Pb B o n Pb A i s signiTican ta tth e 10 $ level , an

d th e lin e draw n i n Fig . 10. 5 i s th e equatio n Pb B = 16. 4 + 2. 4 Pb

A wher e Pb B i s i n ug/10 0 g an d Pb A i n ug/ m

. Thus , I T th e relatio ni s considere d t o b e causative , an d t o demonstrat e th e contributio no T ai r lea d t o bloo d lead , the n th e correspondin g valu e o r a i s 2.4 . Commentin g o n thei r results , th e author s state : "I t appear s tha t th e bloo d lead leve l i s relate d t o th e ai r lead level , bu t th e ai r lea d leve l i s relate d t o unhygienic , o r lo w socia l condition . Thu s i t ma y no t b e conclude d tha t th e bloo d lead leve l i s relate d t o th e ai r lea d leve l i n term s o T a caus e an d eTTec t relationship" . -120 -P.2 3

I nthe lowe r par t o r Fig . 10.5 , the result s ar e plotte do T a stud y b y Tsuchiy a e t al . (1977 ) o r PbB o T urba nandsuburba nchildren , 1 2 t o 1 5 year s o r age , i nTokyo . Th e diTTerenc e wa s greate r whe nonl y childre nwh o ha dlive di nthe same are a Tra

m 3 year s o r ag e wer e included . Thes e result s ar e plotte di nFig . 10.5 . Th e author s conclude dtha t th e diTTerenc e i nPbB level s betwee nurba nandsuburba n childre nwa s mos t likel y du e t o factor s othe r tha nleadi nambien t air . Howeve r th e possibilit y

o f thi s Tacto r bein g a caus e o T th e diTTerenc e coul dno t b e cate goricall y

denied . Johnso ne t al . (1975 ) compare dbloo dlea di npopulation s livin g nea r a freeway i nLo s Angele s (Pb

A = 6. 3 ug/ m

) andi na deser t are a a t Lancaster , Californi a (Pb A = 0.6 4 ug/ m

) . Th e population s wer e sample di nag e group s I 1-16 , I I 17-3 4 andII I 3 5 year s o f ag e andover . Th e result s (arithmeti c mea nan dstandar derro r o f mean ) ar e give ni nTabl e 10.11 , togethe r wit hvalue s o f a assuming , onc e more , tha t Pb A i s th e onl y

variabl e controllin g PbB . Th e result s usin g geometri c mean s wer e similar . Th e difTerenc e i nPb B betwee nth e tw o population s i s greate r To r youn g peopl e tha nTo r adults . Groupin g male s andremain s together , andassumin g a linea r relatio nbetwee nPb B andPbA , the result s o r Tabl e 10.1 1 sugges t

Adult s (group s I I & III ) : Pb B = 9. 9 + 0. 8 Pb A Youn g person s (groupI ) : Pb B = 9. 5 + 1. 7 Pb A Ther e hav e bee na numbe r o T studie s o T bloo dlea di npopulation s livin g nea r smelters . Th e particl e siz e i s generall y large r nea r smelter s tha ni nothe r urba n conditions , an

dals o th e Tallou t o T leaddus t may b e particularl y

heavy . I nth e stud

y o T Yanke l e t al . (1977) , th e Tollowin g variable s wer e studied : 1 . Ambien t ai r leadconcentration . 2 . Lea dconcentratio no T the soil . 3 . Ag e o r th e child . 4 . Cleanlines s o r th e home . 5 . Th e occupatio no T the parent . I t wa s Toun

dtha t Pb

A (rangin g u pt o 1 7 ug/ m ) an dlea di nsurTac e soi l (u pt o 750 0 ppm ) wer e th e mos t signiTican t Tactors . Table , 10.12 , base do nmultivariat e regressio nanalysis , show s predicte dPb B o T the childre na s a functio no f Pb A an d soi l lead . Fo r al l level s o f soi l lead , th e increas e o f Pb B wit hPb A i s approxi matel y equivalen t t o a = 1 . Ther e i s littl e difTerenc e betwee nvalue s To r soi l lea d50 0 an d100 0 ppm , bu t a t 500 0 pp m th e Pb B level s ar e higher . Th e tabl e i s o T interes t sinc e leadi nroadsid e dus t i nurba narea s i s typicall y o r orde r 100 0 pp

m (Arche r andBarratt , 1976b , Da y e t al . 1975) . 10. 6 Bloo dlea dversu s wate r lead A numbe r o r studie s hav e bee nnrad e o T th e relatio nbetwee nlea di nbloo dan d lea di nwater . A

dirricult y

i s tha t th e leadconten t o T the Tlrst . sampl e o f wa«.«* i draw nTro m a ta pi nth e mornin g i s oTte nmuc hhighe r tha nthat . o T wate r draw nfilte r flushing , owin g t o contac t wit hleadplumbin g overnight .
-121 -I na stud y i n Glasgow , wher e th e wate r i s soT t and lead pipework , common , Moor e (1977 ) Tound a regressio nfo r bloo d lead versu s lea d i n runnin g sample s o f wate r Pb B = 0. 8 + 0. 2 Pb W 

### wher e Pb B an d Pb W ar e i n u mole s pe rlitre . I f Pb B i s i n ug/10 0 g , Pb

W i n Mg/1 , th e regressio n become s Pb

B = 16+0.0 2 Pb

W I n alate rpaper(Moor e e tal . 1977) , th e Glasgow dat awer e re-examine d statisticall y an d acurvilinea rrelatio n between bloo d lea d an d firs tflus h wate rlea d wa s obtained . Thi s suggest s anon-linea rrelatio n between intak e an d bloo d lead , wit h ales s stee p increas e i n Pb

B whe n first-dra w wate rlea d exceed s abou t1 umol/ 1 (20 0 ug/l) , D e Graev e e tal . (1975 ) foun

d a n averag e Pb

B o f 25. 6 ug/10 0 g i n 294 person s livin g i n Gileppe , Belgium , i n house s with sof twate ran d lea d pipes . I n acontro l area , wit h har

d wate ran

d pipe s o f

othe rmaterials , th e mea n Pb B o f 26 1 subject s wa

s 12. 7 Ug/100 g . Fro

m dat agive n b

y Heusghe m an d de Graev

e (1973) , i tappear s tha t Pb W (daytim e samples ) wa s 1040 an

d 20 ug/ l To

rth e tw o populations . Thu

s thes e observation s woul

d b e consisten twit h Pb B = 1 3 + 0.01 3 PbW

. Moor e too k th e averag e dall y adul t intak e o T wate r t o b e 2 1 . Fro m ICR P (1975 ) dat a thi s i s probabl y a n overestimate , althoughi t i s very diTTicul t t o b e certai n o T th e contributio no T wate r use d i n cooking . Windl e Taylo r (1971 ) foun d tha t th e averag e amoun t o f wate r take na s drinkin g water o r i n beverage s mad e u p fro m ta p water (3 9 me n an d 8 women ) wa s 1.2 6 1 . Usin g thi s figure , Moore' s regressio n implie s tha t additio no f 10 0 u g P borall y i n wate r increase s Pb B b y 1. 6 ug/10 0 g . Howeve r the late r pape r o f Moor e e t al . (1977 ) seem s t o impl y a large r effect , wit h 10 0 ug/ d orall y

increasing Pb B b

y abou t 5 ug/l0 0 g . I n Tabl e 10.13 , thes e result s ar e compare d wit hestimate s derive d fro m th e experimenta l P bdosing experiment s o f Kehoe , Stui k and Zielhuis , an d Rabinowit z e t al . i n term s o f th e increas e i n bloo d lea d (APbB ) i n relatio nt o the extr a ora l lea d (Al) . Als o give ni s a theoretica l estimat e base d o n fractiona l uptak e fro m th e gut , f = 0.15 , fractio no f uptak e fro m © 

### gu tattache d t o re d cells , f b 

### = 0.55 , an

d biologica l half-lif e i n bloo d T ^ = 18 d . Stui k an d Zeilhui s gave thei rsubject s ora l dose s o f P b fo r2 1 day s only , an d th e APbB/A

I figur e derive d fro

m thei rresult s shoul d be increase d t o abou t3 t o correspon d t o aquasl-equilibriu m situation . I n Tabl e 10.1 4 fo rcompariso n th e rati o PbB/ I o f tota l bloo d lea d t o totn l ora l intake , accordin g t o variou s authors , i s summarised . Th e estimate s o f

I ar e base d o n survey s o f

lea d i n diet , o rlea d i n feces , an d d o no tallo w fo ruptake i n th e lung s o f P b i n ambien

tai ro ri n cigarettes . Ther e i s als o som

e doub twhethe r dietar y studie s ca n b

e sufficientl y exhaustiv e t o Includ e ever y sourc e o f ora l Intake . Th

e rati o PbB/

1 i n th e US

A studie s o

T Kehoe , GriTTi

n e tal. , an

d Teppe r an d Levin appear s highe rthan tha to T th e Europea

n studie s o rNordma

n (1975 ) an

d

-122 -P.2 5 Zurl o and GriTrin i (1074) . 'g'hi s ma y partl y reTlec tlowe rdietar y lea d and ahighe r proportiona l contr''-,:»'Lio n o f inhale d lea d (ambien tan d cigarette ) i n th e USA . 10. 7 Lea

d i n chilG : ••;;-. :s biuot i Childre n hav e ahighe rmetaboli c rate tha n adults , an d the y inhal e more ai r and ea tmor

e Tood , pe runi tbod y weight . Barltro p (1972 ) culoulate d tha ta2 ym r ol d child , whos e bod y weigh twa s 18 $ o

T tha to ra n adult , ingest s 50 $ a s muc h lea d i n diet , an d inhale s 40 $ a s muc h lea d i n ai ra s an adult . I T th e Tractiona l retentio n i n th e lun g ( T ) , an d Tractiona l uptak e Tro m th e gu t( f

) , ar e th e same ag i n adult s and children , then , o n Barltrop' s figures , th e 2 yea rol d child' s uptak e o rlea d pe runi tbody weigh twoul d b e 2 t o 3 time s tha to ra n adult . Fo ra1 0 yea r ol d child , th e Tactor s ar e a s show n i n Tabl e 10.15 . Moreover , ther e i s evidenc e tha tbot h f an d f . ma y b e greate ri n childre n tha n i n adults . Th e retentio n o raerosol s i n th e lun g depend s o n th e dimension s o T th e airway s passages . Takin g thi s int o account , Jame s (1978 ) ha s calculate d th e uptak e o

T particulate s b

y inhalatio n b

y a1 0 yea rol d t o b e 1. 6 t o 2. 7 time s tha to rama

n pe runi tbody weight , dependin g o n th e particl e siz e an d leve l o r physica l activity . Fo rchild/woman , th e ratio s ar e 1. 1 t o 1.3 . HoA-ever, severa l survey s o T bloo d lea d i n childre n an d thei rmother s (Tabl e 10.16 ) sho

w ratio s child/mothe ro T 1. 2 t o 1.4 , whic h i s abou tth e same a s th e rati o o rai rintake s an d rathe rles s tha n tha to T Too d intake s (Tabl e 10.15) . A s th e Pb B rati o i n adul tman/woma n i s als o abou t1. 3 (Goldsmit h and Hexter , 1967 , Teppe rand Levin , 1975 , Flind te tal . 1976) , i tappear s tha tther e i s littl e diTTerenc e i n Pb

B i n childre n and adul tmale s unde rsimila renvironmenta l conditions . Presumably , i T th e Tractiona l retentio n i n th e lung , an d th e Tractiona l uptak e Tro m th e gu tar e highe ri n childre n tha n i n adults , thes e Tactor s ar e balance d b y more rapi d turn-ove ro rlea d i n th e child' s body . Thi s conclusio n ma y no tb e vali d i n heavil y contaminate d area s nea rlea d smelters , wher e Tallou toT lea d an d hig h level s i n dus tcontribut e anothe rmod e o T entry . 10. 8 Resorptio no T leadTro m bon e On e o rth e mos tdiTTicul taspect s o T predictin g lon g ter m relationship s o r lea d i n bloo d t o lea d inhale d o ringeste d i s th e resorptio n an d re-entr y int o bloo d o T lea d store d i n bone . Sinc e th e tim e scal e ove rwhic h thi s occur s i s oT orde r years , onl y ver y lon g term experiment s ar e directl y relevant , thoug h indirec testi mate s ca n b e mad

e by variou s means . Th e evidenc e To ran d agains tasigniTican t contributio n o

T bon e lea d t o bloo d lea d ma y b e summarise d a s follows : (a ) Kehoe' s experiment s Afte rth e conclusio n o f th e period s o f

dail y ora l ingestio n o rlead , Keho e (196lb ) maintaine d measurement s o T th e lea d balanc e o T thre e subject s Torperiod s o T 89 6 (EB) , 28 0 (MR ) and 16 8 (IF ) days . Fro m Fig . 1 1 oT Kehoe' s paper , whic h give s th e accumulativ e lea d balance , i tca n b e deduce d tha tth e store d lea d wa s eliminate d wit h apparen tdeca y constant s X o T abou t0.3 , 0.0 8 an d 0. 6 yr ~ respectively . Keho e note d th e discrepanc y Iwt.wfen th f rrs»ili.« i

-123 -wit h MR , wh o eliminate d onl y abou t8 $ o rhi s store d lea d i n 1 0 luna rmonths , an d EB , wh

o eliminate d hal T i n 2 3 months . Keho e doe s no tgiv e inTormatio n t o sho w whethe rth e resorptio n Tro m bon e was reTlecte d i n Pb B levels , bu tI T th e fractio n o

T th e eliminatio n tha ttoo k plac e i n urine , an d th e rena l clearance , wer e normal , the n asubstantia l contributio n t o Pb B woul d b e expected . (b ) Bone lea d versu s ag e Barr y (1975 ) Toun

d tha tlea d i n th e skeleto n o T non-occupationall y expose d person s increase d wit h age . However , th e rat e oT increas e (Fig . 10.6 ) correspond s t o alon g ter m storag e oT abou t9 ug/d . The averag e uptak e o r lea d Tro m th e gu ti n th e U

Ki s probabl y abou t4 0 ug/d . I T abou thal T o T thi s goe s t o storage , the n asubstantia l part , bu tprobabl y no tall , o T th e storag e ma y b e TorliTe . (c ) Bloo d lea d versu s ag e Barr y (1975 ) Toun

d n o signiTican teTTec toT ag e o n P b i n bloo d o rsoT t tissu e a tpos tmortem , and Teppe ran d Levi n (1975 ) Toun

d n o signiTican t regressio n o

T Pb B on ag e i n asurve y o T 1127 non-smokin g wome n i n th e USA. D e Graev e e tal . (1975 ) i n Belgium , Toun d n o signiTican teTTec to T ag e o n Pb

B i n acontro l population , bu ti n apopulatio n (13 6 men , 8 1 women ) expose d t o hig h level s o

T P b i n drinkin g water , ther e wa s asigniTican tincreas e i n Pb B from 2 0 ug/10 0 g a tag e 2 0 t o 3 1 ug/10 0 g a tag e 61-6 5 fo rme n and 9 Ug/10 0 g a tag e 2 0 t o 2 3 Mg/10 0 g a tag e 61-6 5 fo rwomen . I ti s possibl e tha tany efTec to rresorbe d P b Tro m bon e on Pb

B i n a n agein g populatio n ma y b e balance d b y alowe rora l an d respirator y intake , due t o lessene d activity . (d ) Bloo d lea d i n occupationa l versu s non-occupationa l group s I ti s commonl

y reporte d tha tenhance d Pb B persist s i n highl y expose d occupationa l worker s lon g afte rthei rexposur e ha s ended . Barr y (1975) , foun d mea

n skeletal , sof ttissu e an d bloo d lea d i n non-occupationa l an d forme r occupationa l subject s a tpos tmorte m a s shown i n Tabl e 10.17 . The differenc e i n th e Pb

B valu e o f

th e tw o group s i s oT doubtfu l significance , bu ti f i ti s accepte d an d ascribe d t o resorbe d bon e lead , the n asimpl e pro-rat acalcula tio n indicate s tha tver y approximatel y aquarte ro f Pbf c i n 6 noma ! adul t<TO V b e derive d from skeleta l lead . (e ) Isotopi c ratio s i n lea d and bloo d Manton (1973 ) measure d th e relativ e abundanc e o f th e stabl e lea d Isotope s Pb , P

b an d ^°P b i n th e bloo d o rtw o Sout h African s wh o had live d i n Dallas , Texa s Tor8 an d 5. 5 year s an d als o i n th e bloo d o T thei rAmerican-bor n wives . DirTerence s wer e ascribe d t o resorptio n o T lea d Tro

m bon e whic h had bee n lai d dow

n i n Sout h ATric awher e th e isotopi c ratio s i n die tdiTTe rTro m thos e i n th e USA . I n afurthe rpape r(Manton , 1977) , thi s analysi s ha s bee n refine d t o sho w tha t4 t o 8 $ o f asubject' s Pb

B i s skeleta l i n origi n durin g

-124 -P.2 7

th e lat e summer , bu t 2 3 t o 25 $ i n winter . Th e sensona l variatio ni * at*rrlhr d t o variation s i n vitami nD .
204 , 20 4 (T ) UCL A experiment s wit h P b As previousl y discusse d i n Sectio n 10.4 , th e 'plateau ' level s o f ""'Pb i n bloo d showe d tha tonl y abou thal f th e tota l Pb

B coul d b e ascribe d t o curren t dietar y lead . Unles s ther e wer e unidentiTie d sources , th e remainde ri s attributabl e t o skeleta l lea d and Inhale d lead . A n analysi s o

T th e likel y inpu tTro

m airborn e lea d (Pb

A = 2 ug/

m ) , suggest s tha tthi s migh taccoun t Tor2 5 t o 30$ , leavin g 2 0 t o 25 $ o rPb B ascribe d t o resorbe d bon e lead . Th e conclusion s ar e bound t o b e uncertain , and i ti s no teas y t o envisag e experiment s orsurvey s whic h woul d mak e the m mor e certain . I T 25 $ oT Pb B i n a n adul ti s ascribe d t o skeleta l lead , an d 75 $ t o curren tdietar y and respiratory uptake , the n afactor100/7 5 = 1. 3 shoul d b e applie d t o a(a s estimate d Tro m experiment s lastin g u p t o severa l hundre d days ) t o allo w To rth e eventua l re-entr y int o bloo d o rlea d whic h i s transTerre d t o storag e initially . 10. 9 Possibl e schem e o ruptak e an d excretio n o

T lea d As mentione d i n th e introduction , th e idea l objec twoul d b e t o understan d th e contributio n oT al l th e variou s source s o rlea d t o PbB . I n Tabl e 10.1 8 apossibl e schem e o rsuc h abalanc e shee ti s given , Toran adul tmal e residen to T alarg e cit y i n th e U.K . Pb

A ha s bee n take n a s 1 ug/ m , whic h i s nea rth e uppe rlimi to rannua l means reporte d rro

m th e centra l area s o T citie s suc h a s Birmingha m (Arche rand Barratt , 1976a) , Bristo l (Da y e tal . 1977 ) and Londo n (Lawthe re tal . 1973) , exclud in g th e immediat e vicinit y o T majo rroads . Th

e amoun to T ai rbreathe d ha s bee n take n a s 1 5 m /d , an d depositio n i n lun g a s 50$ . Th e uptak e rro

m roo d an d drin k ha s bee n take n a s 4 1 ug/ d (t5 $ absorptio n i n th e gut ) a s compare d wit h 3 0 ug/ d (10 $ absorption ) whic h i s commonl y take n (e.g . Barltrop , 1972) . As mentione d previously , th e 10 $ absorptio n oTte n quote d seem s t o b e base d largel y on comparison s o rurinar y and dietar y lead , wit h n o allowanc e Torendogenou s Teca l excretion . Th e Harwel l rindin g o

T F A ' = 0.5 , i s o T considerabl e importanc e i n drawin g u p balances . Th e Pb B leve l o r2 2 ug/10 0 g i n Tabl e 10.1 8 i s tha tToun d i n adul tnon occupationa l l y expose d male s i n Manchester . A simila rleve l ha s bee n reporte d from Birmingha

m (DOE, 1978) . The urinar y excretio n i s 2 4 ug/d , from Thompson' s (1971 ) measurement s on 5 Mancheste rmales . Th e rena l clearanc e i s thu s 100/2 2 = 4. 5 g/h r(compar e Tabl e 10.9) . With FgA J = 0.5 , endogenou s feca l excretio n i s 1 2 Mg/d , an d ther e i s ane tpositiv e balanc e o r1 2 Ug/d . Barr y (1975 ) Toun d a n accumulatio n oT skeleta l lea d equivalen tt o 9 ug/ d (Fig . 10.6) . I n th e exampl e o rTabl e 10.18 , Pb A contribute s 7. 5 ug/ d t o uptak e o rlead , wherea s roo d an d drin k contribut e 4 1 ug/d . I n th e USA, wher e Pb A ma y b e highe ri n NOTM : »-l»l#- s

-125 -P.2 8

anUth t lead conten t o f food i s lowe r accordin g t o som e authors , th

e proportionat e contributio no T Pb

A ma y b e higher . I t wil l als o b e highe r i n restricte d zone s

. 3 alongsid e motorway s an d bus y urba nroad s i n th e U.K. , wher e Pb A exceed s 1 ug/ m (Sectio n3. 5 above) . A tabl e simila rt o Tabl e 10.1 8 coul d b e draw n u p To rama n wh o drink s 1.2C

. l/ d O T wate rwit h lea d conten t10 0 ug/l , i n additio n t o th e normal dietar y intake . Assumin g 15J

( uptak e Tro

m th e gut , th e contributio n from wate ri s 1 9 ug/d . Assumin g othe rintake s a s i n Tabl e 10.18 , th e tota l intak e i s the n 4 8 • 1 9 = 6 7 ug/d . I f th e relationshi p betwee n uptak e an d Pb B i s linea rthe n Pb

B woul d b e increase d t o 2 3 x 67/4 8 = 3 2 ug/10 0 g . Thus a n increase d intak e o f 126 ug/ d give s a n increase d Pb B o f 9 ug/10 0 g . I n th e notatio n o f Tabl e 10.13 , APbB/Al = 7 ug/io o g pe r 10 0 ug/d . Thi s i s abou ttwic e a s grea ta n increas e a s appear s fro m experimenta l studies . Probabl y th e explanatio n lie s i n anon-linea rrelatio n betwee n Intak e o f lea d an d Pb

B (Moor e e tal . 1977) . I ti s possibl e tha tther e are.significan tsource s o f uptak e no taccounte d Tor . Tw o possibilitie s ar e lea d i n cigarette s an d lea d i n hous e dirt . Comparison s oT Pb B i n smoker s and non-smoker s hav e bee n inconclusive . Teppe ran d Levi n (1975) , wit h women subjects , Toun d Pb B = 17. 3 ug/10 0 g To rsmoker s compare d wit h 15. 8 Ug/10 0 g Tornon-smokers . A contributio n Tro m ingestio n o T dus ti s eve n mor e diTTicul tt o assess . I T i ti s important , i tshoul d aTTec tchildre n more tha n adults , an d th e compariso n o T Pb B i n childre n and thei rmother s (Sectio n 10.7 ) doe s no tsugges taver y larg e factor . A valu e oT aca n b e deduce d Tro m Tabl e 10.1 8 wit h th e provis o tha tas o deduce d reTer s no tt o th e eTTec to n Pb B o T a n additiona l intak e o rlea d Tro m Pb A bu trathe r t o th e contributio n oT Pb A t o th e tota l PbB . B y proportion : Tota l uptak e o

T P b = 4 8 ug/ d Uptak e Tro

m ai r= 7. 5 ug/ d (Pb A = 1 Ug/m 3 ) Tota l Pb B = 2 2 ug/10 0 g

7. 5 x 2 2

_- A 

### a 

### = 

### —5 5 3. 4
Calculate d i n thi s way , a include s th e contributio nfro m lea d whic hi s trans ferre d t o storag e i n bon e bu t subsequentl y resorbed , a s i t refer s t o a long term balance . Fo r comparison , th e valu e o f a obtaine d fro m th e P bwor k (2. 0 ug/10 0 g pe r ug/ m

i f depositio ni n lun g i s 50$ ) shoul d b e increase d by whateve r facto r i s deduce d fro

m th e dat a o n resorptio no f store d P breferre d t o i n Sectio n10.8 . I f thi s facto r i s 1.3 , the na (long-term ) become s 2. 0 x1. 3 = 2.6 . (1 ) Griffi ne t al . (1975) , an d Boge ne t al . (1976 ) bot hfound dail y intak e o f 10 0 t o 12 0 Ug/d . Bot hstudie s wer e fro m the Easter nStates . Keho e (196la ) foun d a mea n 23 0 ug/ d b

y analysin g th e foo

d and beverage s o f 1 0 o T hi s associate s i n Cincinnati . Howeve r Rabinowit z (1974 ) i n Lo s Angele s Toun d a norma l die t t o contai n36 5 Ug/d , an d tw o speciall y

selecte d low

lead diet s (250 0 calories ) containe d 16 7 an d 18 5 ug/d . H e als o Toun

d tha t th e P bconten t o T food a s determine d b y hi s metho d (spikin g wit h 2 ° 8 P bfollowe d by

mas s spectrometry ) gav e highe r result s tha nmethod s use d elsewhere , possibl y owin g t o th

e dlfricult y

o T ensurin g complet e dissolutio no r lead i n Tood . Alexande r e t al . (1973 ) Toun d an averag e o T 22 0 ug/ d i n th e diet s o T 4 childre nwit h bod y weigh t betwee n2 5 an d 3 2 kg . -126 -P.2 9

T o compare wit h Tabl e 10.18 , Tabl e 10.1 9 show s th e typica l component s o rlea d uptak e accordin g t o Ainswort h e tal . (1977) . Thes e author s tak e th e dail y lea d i n Too d t o b e 14 3 Ug/d (MAFF , 1975 ) and th e dail y lea d i n wate r4 0 ug/ d (0.0 2 m g Pb/l , 2 1/ d intake) . Wit

h 8 $ an d 10 $ uptak e Tra m th e gu to

T lea d i n Too

d an d wate r respectively , Ainswort h e tal . obtai n atota l dietar y uptak e o T 15. 4 ug/d , whic h i s onl y athir d o

T tha tcalculate d i n Tabl e 10.18 . Assumin g Pb A = 1 Ug/

m , and 35 $ depositio n i n th e lung , Ainswort h e tal . Tin d tha tai rlea d contribute s 25 $ oT th e total . O

n thi s analysis , i T Pb B = 2 2 ug/10 0 g , an d th e variou s component s contribut e pro rat at o PbB , the n a= 5.5 , whic h i s large rtha n othe rmethod s oT calculatio n suggest . Also , th e dail y uptak e o T 20. 6 u g Tro

m gu tand lun g postulate d b y Ainswort h e tal . compare s wit h mea n outpu ti n urin e alon e o rnorma l subject s reporte d a s 2 5 ug/ d (Thompson , 1971) , 3 0 ug/ d (Kehoe , 196la ) an d 3 3 Mg/

d (Rabinowit z e tal . 1977) . Hence , i rth e uptak e i s a s smal l a s 20. 6 ug/d , bot h endogenou s Teca l excre tio n and storag e i n bon e mus tb e negligibl y small . Ther e i s probabl y mor e uncertaint y abou tth e dail y uptak e o T lea d Tro

m Too d an d wate rtha n th e dail y uptak e Tro m th e atmosphere . 10.1 0 Conclusion s Th e variou s estimate s o rth e Tacto rarelatin g Pb B t o Pb A ar e summarise d i n Tabl e 10.20 . A

s alread y discusse d by MahaTTe y (1977) , ther e i s aconsensu s o T experimenta l and epidemiologica l result s givin g ai n th e range 1 t o 2 ug/10 0 g pe r Ug/ m . However , i T instea d o T th e elevatio n oT Pb B t o b e ascribe d t o PbA , th e Tractiona l contributio n o rPb A compared wit h othe rsource s o T lea d i n th e die ti s considere d (a s i n Tabl e 10.18) , an d th e contribution s t o Pb B take n pro rata, th e valu e o T aappear s higher . A simila rdiscrepanc y ca n b e detecte d i n studie s o rth e eTTec to n Pb B o T lea d i n water . The onl y obviou s explanation s ar e either : (a ) ther e ar e importan tunquantiTie d source s o T intak e o rlea d (To rexample , cigarette s an d alcoholi c drinks )
o r(b ) th e relatio n o T Pb B t o lea d intak e i s non-linear , s o tha texposur e t o Pb A doe s no tincreas e Pb B pr o ratat o th e increase d intak e o rlead . Th e sam e poin ti s illustrate d i n Tabl e 10.21 . Th e Tirs tro

w show s th e rati o o T th e intak e o

T lea d Tro

m Pb A t o th e intak e Tro

m dietar y source s accordin g t o th e analysi s o

T Tabl e 10.18 . Thus TorPb A = 1 ug/

m , th e rati o i s 7.5/4 1 = 0.1 8 an d To r Pb A = 2 o r5 ug/

m th e rati o i s increase d pro rat aassumin g alinea rrelationship . Thi s estimat e depend s o n th e lea d conten to rdiet , an d th e Tractiona l uptak e rro m th e gu ta s wel l a s o n th e uptak e o T Pb A i n th e lung . I ti s probabl e tha tth e lea d conten to rdie ti s decreasin g wit h tim e (Ministr y o rAgriculture , Fisherie s & Food , 1975) . I T Pb

A remain s th e same , it s proportiona l contributio n t o tota l lea d uptak e i s likel y t o increase . I n th e secon d ro w o rTabl e 10.21 , th e rati o deduce d b y Rabinowit z e tal . (1973 ) i s given . Fo rasubjec ti n Lo s Angele s expose d t o Pb A = 2 Mg/ m thes e author s deduce d 13 Ug/ d uptak e Tro

m ai rcompared wit h S 3 ug/ d dietary , givin g aratio o

T 0.39 . Th

e las ttw o row s o rTabl e 10.2 1 sho w th e ratio s d*du

rt:<\ from straigh tlin e regression s o f Pb B o n Pb A from Toky o and CaliTorni areTerre d t o i n

•127 -" ' • " f ^ L *^i»^*irn » .I T —p. - P.3 0

Sectio n10.5 . Th e intercep t o r th e regressio no n th e Pb A axi s (i.e . th e extrapolate d valu e o T PbB whe nPb A = 0 ) i s use d t o estimat e th e dietar y contributio nt o PbB . Onc e mor e a linea r relationshi p i s assumed , and n o Accoun t ha s bee ntake no T th e possibl e InTluenc e o T sociologica l and othe r factor s relate d t o residence . Ther e i s conQictin g evidenc e a s t o whethe r th e eTTec t o r Pb A o n PbB , o r th e proportio no T tota l intak e attribute d t o PbA , i s greate r To r childre ntha nfo r adults . Th e analysi s o T Tabl e 10.1 6 and Sectio n10. 7 suggest s littl e diTTerence , bu t th e epi demiologica l studie s i n Toky o and CaliTorni a sugges t a bigge r eTTec t i n children , possibl y

connecte d wit hindirec t uptak e o T lead fro m othe r source s correlate d wit h PbA .

-128 -P.3 1
TAIiL E 10. 1 Sioi-ag c o f

U-a J b y Kehqc' dsubject s rcccivim ; Uaii v ora l Ufasu ^ Subjec t Duratio n o f

dosin g (d ) Approximat e dail y dos e (mg ) Tota l dos e (mg ) P b i n foo d an d drin k (mg ) Tota l ingeste d P

b (mg ) Lea d store d (mg )

- a s fractio n o T ora l dos e

- a s Tractio n o rtota l ingeste d Duratio n o rTollow-u p (d ) Lea d release d Tro

m storag e (mg ) 1 - a s Tractio n o T store d P b S

W 42 0 0 . 3 12 6 8 8 21 4 1 2 0.09 5 0.05 6

-

-

- M

R 145 6 1 144 3 52 8 197 1 11 8 0.08 3 0.06 0 28 0 7 0.0 6 E

B 64 4 2 128 7 13 2 141 9 11 0 0.08 6 0.07 8 89 6 6 8 0.6 2 I F

12 2 3 33 6 27 * 36 3 5 5 0.16 4 0.15 2 16 8 1 5 0.2 7

* Keoh e doe s no t

giv e IF' s dail y P b i n Toodan ddrin k durin g th e experimenta l period
. Th e Tigur e quote di s IF' s dail y P b durin g acontro l period , a s give n b y Keho e (1961a) , Tabl e 12
. TABL E 10. 2 Uptake , excretio n an dstorag e o f lea di n Kehoe' s subject s M Ran dE B
Subjec t
Duratio n (days ) Lea d ingeste d (ug/d )

- i n roo d an d drin k

- i n solutio n

- tota l (I ) Lea d eliminate d (ug/d )

- i n Tece s (F )

- i n urin e (U )

- tota l Lea d store d (S ) (ug/d ) Assumin g F A

J =0. 5 To rbot h Endogenou s Teca l lea d F e(Mg/d ) Uptak e Tro

m gu t(ug/d ) G = U + F e+ S Fractiona l uptak e T g= G/ I Fractio n o T uptak e retaine d f 

### g s - 

### Vf e Assumin g F CAJ = 1 To rEB . ze r F e G
f g f g s M R Dosin g 145 6
36 3 99 1 135 4 119 5 7 8 127 3 7 6 subject s 3 9 19 1 0.1 4 0.4 0

o To rM

R

- 15 4 0.1 1 0.4 9 Follow-u p

28 0
32 9

- 32 9 29 8 5 7 35 5 -2 6

2 8 5 9 0.1 8

^ 3 1 0.0 9 Dosin g

684 "
19 4 188 1 207 5 180 7 10 7 191 4 16 1

5 3 32 1 0.1 5 0.5 0

10 7 37 5 0 % 1 8 0.4 3 E

B Follow-u p 68 4
33 1

- 33 1 34 2 8 0 42 2 - 9 0

4 0 3 0 0.0 9

8 0 7 0 0.2 1

-129 -

### TABL E 10. 3 Lea d balanc e i n Kehoe' s subjec tF C beTore , durin g an

d afte r exposure t o airborn e lea d i n a n experimenta l chambe

r

Length o T stud y (d )

Lea d ingeste d i n Too

d and drin k Lea d inhale d (A ) (deposite d i n lung ) Tota l Lead eliminate d i n fece s (F )

i n urin e (U ) tota l Lead store d i n bod y (S ) Assumin g F

C A J =0. 5 Endogenou s feca l lea d ( F ) Tota l uptak e = U + F g+ S Uptak e fro

m gut=U+F e+ S- A

- a s fractio n o f

ingeste d (Ts ) Retaine d lea d a s fractio n o f tota l uptak e f s = S/( U + F f i + S ) Preliminar y perio d 53 2 Tota l m g IS O

13 0 11 1 1 2 12 3 7
8. 6 2 5 2 5 ug/ d

24 4

24 4 20 9 2 3 23 2 1 2
11. 5 46. 5 46. 5 0.1 9 Experimenta l

perio d 61 6 Tota l m g 13 4 9 8 23 2 14 0 4 5 185 4 7
22. 5 114. 5 Ug/ d

21 7 15 9 37 6 22 7 7 3 30 0 7 6
36. 5 185. 5 16. 5 | 26. 5 0.1 2 0.3 8 Follow-u p

perio d 53 2 Tota l m g 9 1

9 1 8 0 1 4 9 4

- 3

7 1 9 1 9 Ug/ d

172

172 15 0 2 7 177

- 5
13 5 35. 5 35. 5 0.2 1

TABL E 10. 4

20 4 Endogenou s Teca l excretio no T Pbb y UCLA subject s Subjec t
A
B

C
D
Mea n Day s from

star to f experimen t IS O 15 0 13 0 14 0 15 5 17 1 22 7 11 0 139 Day s from

en d o f dosin g 26 4 6 6 1 6 3 1 4 7 103 2 8 5 7 End. feca l

excretio n Ug/ d 1. 8 1. 2 2. 6 1. 5 1. 2 0. 7 0.0 5 1. 7 1. 0 204 P b i n

bloo d Mg/ g 0.026 5 0.011 8 0.039 4 0.029 9 0.020 5 0.013 1 0.002 5 0.028 2 0.016 0 End.feca l

g blood/ d 6 8 10 2 6 6 5 0 5 9 5 3 2 0 6 0 6 3 6 0 clearanc e

g blood/ h 2. 8 4. 3 2. 8 2. 1 2. 5 2. 2 0. 8 2. 5 2. 6 2. 5

-130 -P.3 3

TABL E 10. 5 

### 20 4 Uptak e an

d storag e o T P

bi n UCLA

subject s give ndall y ora l dose s Subjec t Duration o T trace r intak e (d ) 1 20 4 P bingested (ug/d ) 204 P beliminated (ug/d )

- i n fece s

- i n urin e (U ) 204 P bstored (S ) (ug/d )

- tota l (ug ) P bi n bon e a t biops y (Mg ) Endogenou s feca l excretion(F g ) (ug/d ) Uptak e fro

m gu t (Mg/d ) G = U+ F g + S

- a s fractio

n o f ingested ( f ) Fraction o T uptak e stored T = S/ G g s | A

10 4 20 4

18 8 8. 4 8 83 0 70 2 4. 4 2 0 0.1 0 

# °- 4 B

12 4 . 18 5

17 4 4. 7 6 63 0 67 4 1. 8 1 3 0.0 7 0. 5 D

8 3 10 5

9 4 5. 4 5

1. 8 1 3 0.1 2 0. 4 Note s

(a ) (a )
(a ) (b )
(c ) (a ) (d )

Notes : (a ) Dat a o T Rabinowit z e t al . (1976b ) (b ) Th e dail y

tota l P bi n urin e wa s 0.41 , 0.2 7 and 0.3 6 M g To r th e subject s A , B , D . Th e isotopi c ratio s i n bloodan d urin e wer e identica l a t al l times . Th e averag e dail y 204p D^ g calculate d b y multiplyin g th e tota l Pb Ub y the 204pb/tota l P brati o i n blood . Thi s las t rati o wa s deduce dTro m th e 204 Pb B and tota l PbB figure s 

# f ive nb y Rabinowit z e t al. , average do n th e duratio no T intak e o r 04p b . (c ) Th e bon e biops y

o n subjec t A

wa s don e o n day

115 , aTte r th e end o r the dosin g period , bu t o n subjec t B o n da y 105 , beTor e th e endo T dosin g (Rabinowitz , 1974) . Th e tota l storag e o T 204 P b ha s bee ncalculate du p t o th e time o T biopsy . (d ) F

_calculate dfro

m th e endogenou s Teca l excretio nmeasure daTter the end o T dosing , assumin g th e rat e bot hdurin g and aTte r dosin g t o b e proportiona l t o 204 PbB . TABL E 10. 6 2CV 4 Estimate s o

T halT-liT e o

T P b i n bloo d o

T UCL A subject s Subjec t Estimate d bloo

d mas s T ^ (days ) b

y metho d (a )

(b ) (c ) Analysi s o r Rabinowit z e t al . (exchang e rate s o T Tirs t pool ) X" ' (days ) T ^ (days ) A 4. 9 2 4 1 8 2 3

3 4 2 4 B

6. 3 2 8 2 4 3 0

4 0 2 8 C

6. 3

3 7 2 6 D

4. 6 3 1 3 6 2 5

4 0 2 8 E

6. 3
1 8

2 7 1 9

-131 -r TmjfT r^'Trrw

r -r^ -

TABL E 10. 7 204 , Pban d tota l Pbi n die t an d bloo do T UCL A

subject s (Rabinowit z e t al . 1976b ) Subjec t
204 Pb B a tplatea u (ug/l0 0 g ) Tota l Pb

B (ug/10 0 g ) Rati o 204 Pb/P b i n bloo d Ora l dos e oT 204 P b (Mg/d ) Dietar y P

b (Mg/d ) Tota l ingeste d P

b (Mg/d ) 20 4 Rati o Pb/T b ingeste d Fractio n o rbloo d lea d attribute d t o curren tdie t A 7. 6 2 5 0.3 0 20 4 156 36 0 0.5 7 0.5 3 B

4. 8 1 8 0.2 7 18 5 17 9 36 4 0.5 1 0.5 3 D

5. 4 2 0 0.2 7 10 5 18 8 2S 3 0.3 6 0.7 5

TABL E 10. 8 Inhale dleadIntak e b y thre e method s (Mg/d ) (Rabinowit z e t al . 1977 ) Subjec t
Lead balanc e Bloo d labellin g Respons e t o Tiltere d ai r A
16 2 4 17 * 5

- B
1 9 : 3 16 2 6 16 1 3 D

1 2 2 6 8 1 4 9 1 3 E

7 1 6

1 2 1 2

-132 -TABL E 10.1 2 Predicte d mea n childhoo d bloo d lead (Mft/lO O ml ) To r variou s ai r an d soi l lead concentration s nea r amelte r (Yanke l e t al . 1977 )

Ai r , U g Pb/ m
1 2 3 4 5 Soi l (pp m lead ) 50 0 26. 7 27. 8 29. 0 30. 2 31. 5 100 0

27. 0 28. 1 29. 3 30. 5 31. 8 500 0

29. 3 30. 5 31. 8 33. 1 34. 5

TABL E 10.1 3 Elevatio no r bloo d lead Tro m ora l intak e o T lea d

Autho r an

d subject s
Keho e (1961 ) S W M R E B Stui k & Zielhui s

(1975 ) 5 male s 5 Temale s Rabinowit z (1974 ) Rabinowit z e t al .

(1976b ) Preliminar

y subjec t Subjec t A

B D
Moor e 197 7 Moor e e t al . 197 7 Theoretical , assumin g Period or experimen t (days )

42 0 36 4 64 4

21 2 1

4 5 10 4 12 4 8 4 Derive d Tro

m assuming tap

i t 

## r = o.is , r . g g

t P b(Mg/d ) give n orall y

30 0 100 0 200 0

140 0 120 0

7 5 20 4 18 5 10 5 regressio

n o wate r intake I I u

3 = 0.5 , D j = Pb

B (Mg/10 0 g ) BeTor e

3 2 3 0 3 9

2 0 1 2 ATte r

3 7 5 5 6 8

4 2 3 0

< 204 PbB )
Ni l Ni l Ni l Ni l 1. 7

7. 4 4. 7 4. 5 T Pb B o nPb W o r 1.2 6 1/da

y II 1 8 d Increas e i n Pb B ug/10 0 g pe r 10 0 Mg/d ) (APbB/AI )
1. 7 2. 5 1. 4

1. 6 1. 5

2. 3 3. 6 2. 5 4. 3
1. 6

- 5 3. 6

-135 -P.3 6

TABL E 10.1 4 Bloo d lea d an d dietar y lea d (foo d an d drink )

Se x
F M M M F M Ora l intak e

I (Mg/d ) 12 4 11 3 23 0 23 0 18 0 50 5 Pb

B (Mg/10 0 g )
16. 2 19. 0 2 6 12. 3 7. 9 32. 9 PbB/ I

(Mg/10 0 g pe r10 0 ug/d )

1 3 1 7 1 2 5. 4 4. 4 6. 5 Reference s

Teppe r& Levi n (1975 ) Griffi n e tal . (1975 ) Keho e (1961 ) Nordma n (1975 ) Nordma n (1975 ) Zurl o & GrifTin i (1974 )

TABL E 10.1 5 Rati o o T intake s oT ai ran d Too d pe runi tbloo d volum e fo r1 0 yea rol d childre n and adult s (dat afrom ICRP , 1975 )

Ai r(resting ) Ai r(ligh tactivity ) Foo d Chil d Ma n 1.5 8 1.6 1 1.6 5 Chil d

Woma n 1.4 9 1.2 7 1.7 7 Woma

n Ma n 1.0 7 1.2 7 0.9 3

-136 -P.3 7

TABL E 10.1 6 Lea d i n bloo d o

T childre n and mother s (numbero rsubject s give n i n brackets )

Locatio n Matloc k & Buxto n Derbyshir e village s E . Londo

n
Bristo l
N . Wale s (coppe rpipes ) N . Wale s (lea d pipes ) Ag e o T childre n 2- 3
2- 3
Pre-schoo l
Unde r10 ( 1 )

Unde r1 6
Unde r1 6 Pb

B Childre n 23. 2 (180 ) 23. 2 (82 ) 3 3 (144 ) 16. 2 (64 ) 19. 2 (19 ) 41. 6 (38 ) (Ug/10 0 ml )

Mother s 19. 1 (175 ) 16. 1 (74 ) 27 (107 ) 13. 5 (24 ) 13. 9 (19 ) 39. 5 (38 ) Rati o

1. 2
1. 4
1. 2
1. 2
1. 4
1. 1 ReTerence s Barltro p e tal . (1 9 74 )
Barltro p e tal . (1975 )
Lansdow n e tal . (1974 )
Da y e tal . (1977 )
Elwoo d e tal . (1978 )
Elwoo d e tal . (1978 )

(1 ) Childre n wer e groupe d i n ag e range s 0- 5 an d 5-10 . Pb

B wa s no t signiTicantl y diTTeren ti n th e tw o groups .

TABL E 10.1 7 Lead i n tissue s a tpos tmorte m (Barry . 1975 )
Subject s Occupationa l Non-occup ationa l P b (mg) i n bon e 50 7 15 5 soT ttissu e

1 4 9 Pb 

## in^{o2 § 8 )

Mea n 3 1 2 0 S.E .

6 2

-137 -TABL E 10.1 8 Scheme o f

uptak e and excretio n o T lea d b y adul tmal e i n urban distric to

T U.K . P.3 8 -'—'Ty'—W||»
-

Uptak e Intak e i n foo d an

d Fractio n absorbe d Uptak e Tro

m gu t Uptak e fro

m lun g

Tota l uptak e Excretio n Bloo d lea d Urinar y excretio n Endogeneou s Teca l Tota l excretio n Storag e drin k

i n gu t

excretio n 27 0 Mg/ d 0.1 5 4 1 Ug/d 7. 5 Mg/ d

4 8 Mg/ d

2 2 Mg/10 0 g 2 4 Mg/ d 1 2 Mg/ d 3 6 Mg/ d 1 2 Mg/ d R

e Terence s and Note s Thompso n (1971 ) Se e Table s 2 , 3 , 5

Pb A = 1 Ug/m 3
r a=0. 5

Flind te tal . (1976 ) Thompso n (1971 ) Assumin g F A

j = 0. 5

Compar e Fig . 10. 6

TABL E 10.1 9 Relativ e contribution s t o uptak e o T lead i n analysi s o r Ainswort he t al . (19773 "

Intak e Mg/

d
Foo d 14 3 Wate r4 0 Ai r1 5 Percentag e

uptak e 8 $ 10 $ 35 $
Tota l Mg/

d 11. 4 4. 0 5. 2 Uptak e $ o T tota l 55 $ 19 * 25 $
20. 6

-138 -P.3 9

TABL E 10.2 0 Summar y o restimate s o

T elevatio n o

T bloo d lea d oT adult s Tra m exposur e t o ai rlea d

Metho d 20 3P b

203 ; P b

20 3P b

Exposur e o

T subject s t o Pb A

I I i t < i
Epidemiologica l ug/10 0 g pe rMgAi"

j Fro m estimate s o ruptak e i j an d excretio n j 

### i L 1. 1

2. 0

2. 6

1. 2
1. 6

2. 4

0. 8 3. 4 Rererence s an d Note s

Chamberlai n e tal . (1975) , wit h T f i = 0.35 , T a b = 0.5 , T,

^ = 1 6 d . Revise d estimat e wit h T f i = 0.5 , T af

c= 0.55 , Ti ^ = 1 8 d . A s above , i f

a n additiona l facto r 1. 3 fo rlon g term resorptio n o f bon e i s assumed . Keho e (1961b , 1966 ) (se e Tabl e 10.9 )
GriTTi n e tal . (1975 ) (se e table s 10, 9 an d 10.10) . Tsuchiy ae tal . (1975 ) - se e Fig . 10. 5 assumin g al l variatio n i n Pb B ca n b e ascribe d t o PbA , bu tnot e authors ' commen ta troo to f

p.120 . Johnso n e tal . (1975 ) (se e Tabl e 10.11) . Sectio n 10. 9 abov e and Tabl e 10.18 .

TABL E 10.2 1 Summar y o T estimate s oT rati o oT contribution s o T ai rlea d t o othe rlea d intake s (adults T

Metho d

A s i n Tabl e 1 8 20 4 P b(Rabinowit z e t al . 1973 ) (Lo s Angeles ) PbB/Pb A regression o T Tsuchiya e t al . (1975 ) - se e Section 10. 5 (Tokyo ) PbB/Pb A i n CaliTomi a (Johnso ne t al . 1977 ) - se e Sectio n 10.5 . PbA/othe r a t Pb A level s o T 1 Mg/ m 0.1 8 0.2 0
0.1 5
0.0 8 / 3

2 Mg/t o 0.3 6 0.3 9
0.2 9
0.1 6 5 ug/ m

0. 9 1. 0 0.7 3 0. 4

139 -P.4 0



## o o O t S t O O

0

_ 

## o C M



### 5 0 10 0 15 0 Tim e fro m star t o

f dail y dos e (days ) A.E.R.E.R9198 . FIG.10.1 . 20 

### *P b I N BLOO D O F UCL A SUBJECT S (RABINOWITZ , et al.1976b ) CURVE S AR E FITTE D B Y METHOOIc ) O

F SECTIO N 10.3 .

-140 -*-TT*HWWP.4 1



## a.
J I I I I I ' ' i I i T—i—i— r

I I 

# I I I X 10 0 

## 30 0

20 0 Tim e (days ) A.E.R.E.R9198 . FIG.10.2 . LOS S OF 20 

### *P b FRO M BLOO D O F FOU R SUBJECT S AFTE R WITHDRAWA L O F ISOTOP E FRO M DIET(RABINOWITZ et al.1976b) .

-141 -P.4 2 "-**nr- "" •



# 2

U J 1 1



### Th e th e —— t 1——

j 1 , 1 1 r 

### number s neo r th e point s or e number s o

f subject s Bs1 6 0(1-exp-00245t l

B = 5 3(1-exp- 0 0266t )

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-142 -P.4 3



### Day s A.E.R.E.R9198 . FIG.10.4 . INCREAS E O F Pb B I N TOL A e t al' s SUBJECT S ON BEGINNIN G WOR KI N TH E LEA D INDUSTRY .

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A FEMAL E CHILDRE N (TSUCHIYA et ol . 1977 . TABL E 3) .

-144 -

### E.R.E.R9198 . F1G.10.6 . LEA D I N DEATH.NORMALISE D T O 70k g BOD Y 

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SKELETO N A

T WEIGH T

-14S .Acknowledgement s Thank s are du

e t o th e voluntee r subject s Messrs . D.H.F . Atkins , K.F . Bi9hop , R.H . Houna m an d Dr . A.N.B . Stott . Dr . Stot t als o supervised th e experiment s medically . Messrs . R.C . Flemin g an d M . Eagl e helped wit hth e experimenta l work , an d Messrs . R.J . Evan s an d J.F . Smit h too k th e bloo d samples . Dr . M . Inski p an d Mr . M . J . Dugga n provided racilitie s To r ai r samplin g a t Chelse a Colleg e an d Count y

Hal l respectively . Mrs . M . J . Can n provide d inTorma tio n an d Mis s J . Fen

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