P. 1 

# OAR Box 1128 Prepped by Ollie Stewart



# Document

Number: 

# 37 ) 11-1-21 5 Docket Number: 

# A-83-2 2

Printed 4/21/2008 11:07:11 AM Sheet 37 of 198P. 2

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### In t Arch Occu

p Enviro n Healt

h (1986) 57:225-23 5 

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## Mr^i^.^l^&

lnaa*rsartionat i ArcrUvawo r 

### K.ir.ii'onitif'it?;. '
a ; ? • .- . *• © Springer-Verlag 198 6


# EP A AI R DOCKE

T 

# Th e relationshi p betwee n blood-lea d concentrations , intelligence , attainmentand behaviou r i n a schoo l population : th e secon d Londo n study Richar d Lansdown 1 

### , Willia m Yule 2 

### , Marie-Ann e Urbanowicz 3 

### , an d Ja n Hunter 2 1 

### Department

o f Psychologica

l Medicine , The Hospita

l fo r Sic k Children , London WC1 N 3JH , 2 

### Th e Institute o

f Psychiatry , Londo n 3 

### Th e Inner

London Educatio n Authorit y Research an

dStatistic s Branch , London , Grai t Britain Summary . Thi s stud y replicate s a n earlie r on e carrie dou t

i n Londo n i n whic h a n associatio n wa s foun dbetwee n lea dan dintelligence , readin g an d spelling . I n th e presen t stud y 19 4 childre n livin g nea r a n urba n motorwa y wer e give n th e sam e batter y o f test s a s wel l a s a n extensiv e famil y intervie w t o determin e backgroun dvariables . Befor e socia l factor s wer e take n int o accoun t ther e wer e n o significan t association s betwee n lea dan doutcom e variable . Possibl e reason s fo r th e negativ e result s fro mthi s stud y ar e dis
cussed . Ke y words : Childre n - Bloo dlea dleve l - Attainmen t - Intelligenc e - Be
haviou r Introductio n Thi s stud y wa s undertake n i n orde r t o replicat e astud y (Yul e e t al . 1981,1982 ; Lansdow n e t

al . 1983 ) i n whic h 16 6 childre n age d6 t o 1 2 years , livin g withi n 1 k mo f aLondo n factor y wer e assesse di n school . Th e firs t batter y o f

thi s pilo t stud y consiste do f

th e Wechsle r

Intelligenc e Scal e fo r Children—Revise d (Wechsle r

1974) , th e Neal e Analysi s o f Readin g Abilit y (Neal e 1958) , an dth e Verno n Mathematic s an dSpellin g Test s (Verno n an dMille r 1976 ; Verno n 1977) . Teachers ' rating s o f children' s behaviou r

wer e collecte dusin g th e scal e employe db y Needlema n e t al . (1979) , th e Conner s (1969 ) scal e an dth e Rutte r B 2 scal e (Rutte r

an dYul e 1968) . Blood-lea dconcentration s ha dbee n ascertaine d :aBvWa?BBaa g •..f-'i*'.fs " . .



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# rv?&$& .

Offprint requests to: R . Lansdow

n a t th e abov e addres s"•'.:'-'i>:*y"'i.!^V. !

•ff'i'Z •i'^.-iVXr...-,,., .

ffr^&iy^ . 22 6 R . Lansdow n e t al . 

### 9-1 2 month s prio r

t o th e psychologica

l assessment s a s par t

o f a n EE C survey . Socia l clas s wa s establishe dfromth e fathers ' occupations . Almos t half cam e fromclas s III , manua l labou r (46%) , wit

h 18.6 % in classe s I an dII . The y were , therefore , apredominantl y workin g clas s sample . -- ; Th e mean blood-lea dconcentratio n i n thi s sampl e wa s 13.5 2 ug/10 0 m l (S D = 4.13) , an dther e wa s asmall , bu t statisticall y significant

relationshi p between- J body-leadburden , intelligence , reading , an dspelling . Thi s associatio n remained* * after socia l clas s ha dbee n accounte dfor . Th e patter n o f th e children' s be
haviour , a s rate do n th e scal e use dby Needleman , wa s strikingl y simila r t o tha t reporte di n hi s 197 9 paper , i.e . i n mos t categorie s childre n wit

h highe r lea d level s showe dindication s o f les s acceptabl e behaviour . Th e secon dLondo n stud y wa s designe dt o replicat e th e firs t an dt o improv e o n i t b y (a) examinin g th e relationshi p betwee n outcom e measure s an dtw o esti
mate s of blood-lea dan d(b ) b y gatherin g mor e informatio n o n social factor s though t t o b e relevant . Metho d The sample Th e childre n takin g par t i n th e replicatio n stud y wer e draw n fro mapopulatio n livin g nea r a, mai n roa din anothe r

par t of London . Blood-lea dconcentration s ha dbee n ascertaine db y th e communit y physicia n i n respons e t o areques t fro msom e parent s wh o ha dbee n concerne dbe
caus e o f th e proximit y o f

thei r children' s schoo l t o abus y road . O f atota l populatio n availabl e • f/f.f'-f-'^.f. 2 o f 221 , 87.8 % participate di n th e study , givin g asampl e o f 194 . :::•'-•: i<«£*-S' ^ Investigation of social factors Socia l clas s wa s agai n ascertaine db y establishin g th e fathers ' occupation . A length y structure d intervie w with parent s wa s undertake n t o giv e furthe r information . Thi s interview , whic h too k approximatel y 2 h t o administer , was base do n on e devise dfo r anothe r stud y o n lea dan dchil
dre n als o carrie dou t

i n Londo n (Smith e t

al . 1983) . I t

include dabrie f

assessmen t

of bot h par - ;;,•£.; ifi.-.:-?..\*-3 v ' r >a^^ls^ 3 ents ' lntem gence , usin g tw o subtest s of th e Wechsle r

Adul t Intelligenc e Scal e (Wechsle r 1955) . f • • ii;';'• ] ?'.''; { Blood-lead ascertainment Bloo dha dbee n collecte db y vei n punctur e an danalyse di n th e Departmen t o f Chemical Patholog y an dHuma n Metabolis ma t th e Universit y of

Southampto n unde r

th e directio n o f Dr . Trevo r

Delves . Lea dconcentration s wer e determine do n sample s of bloo dusin g atomi c absorptio n spectrophotometry . A t avalu e of

1 5 ug/10 0 ml , thi s analyti c metho dshoul d achiev e result s withi n ± 10% , provide dth e qualit y contro l i s meticulou s (DHS S 1980) . Ther e i s n o reaso n t o believ e tha t qualit y contro l i n thes e analyse s wa s anythin g bu t meticulous . A secon dbloo dsampl e was take n fro m162 childre n afte r th e psychologica l assessmen t wa s completed , som e 2 0 month s elapsin g betwee n th e tw o measures . Analysi s wa s carrie dou t i n th e sam e laboratory . Test battery Th e test s an dteachers ' rating s tha t ha dbee n use din th e pilo t stud y wer e employe dagain , give n unde r

th e directio n o f

th e sam e fiel dsupervisor . Al l testin g was carrie dou t i n th e chil
dren' s school s b y traine dpsychologist s wh o wer e blin dt o th e lea dlevels . Behaviou r wa s rate d b y th e sam e scale s a s ha dbee n use di n th e pilot , plu s aratin g b y parent s (Rutte r e t al . 1970) .

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Lea deffect s o n intelligenc e attainmen t an dbehaviou r

22 7 

### Results Social class distribution A s ca n b e see n fro

mTabl e 1 , th e presen t

sampl e containe damuc h highe r pro portio n o f middl e clas s childre n (define da s classe s I , II , an dII I non-manua l labour ) tha n ha dbee n presen t in th e pilo t

study : 55.2 % v s 18.6% . Tabl e 1 . Social-clas s composi
tio n o f th e sampl e an dth e pilo t stud y

.Tabl e 2 . Distributio n of blood
lea dlevel s measure dfro mfirs t bloo dsampl e Social-clas s

7 8 9 1 0 3

1 2 8 2 1

194 Sampl e Pilo t • I I I II I non-manua l III manua l I V V Singl e paren t Unemploye d No t know n N

4 7 1 3 2 6 8 8 3 5 2 1 % 2. 1 36. 6 16. 5 35. 1 4. 1 1. 5 2. 6 1. 0 0. 5 N

3 1 1 1 7 7 7 1 9 2 1 2 2 2 3 % 1. 8 6. 6 10. 2 46. 4 11. 4 1. 2 7. 2 1. 2 13. 9 Tota l
P b (ug/10 0 ml ) N 194
/ o 16 6 Quartile s 1. 5 6. 2 4. 1 10. 8 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 24 2 3

3 0 3 2 1 7 2 0 9 4 5 4 3 0 1 0 2 11. 9

15. 5 16. 5 8. 8 10. 3 4. 6 2. 1 2. 6 2. 1 1. 5 0 0; 5 0 1. 0 I I

III

I V

Mea n = 12.7 5 ug/10 0 ml ; S D = 3.0 7 

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:i??-?S-Ji'.V>''' : :••:' • 22 8 Tabl e 3 . Lea dleve l b y social-clas s R . Lansdow n e t al . P. 5 •

N 

### SD I + 1 1 II I N M III M 

## r v 

## + v Singl e paren t an dunemploye d 6 6

3 6 .6 3 1 0 1 4 12.8 8

11.25 : 13.3 4 13.1 8 11.8 6 3.2 2

2.6 5 2.7 9 4.1 2 2.3 4 2.8 7 0.0 2

P b (ug/10 0 ml ) Firs t testin g 

### (A O Secon dtestin g

(A O Tabl e 4 . Summar y of result s of firs t an dsecon dsample s o f blood-lea dlevel s 7-1 0 11-1 2 13-1 4 15-2 7 Tota l Mea n S D 3 7

4 3 3 8 4 4 162 12.8 8 3.1 6 6

.2 5 5 0 8 1 16 2 15.1 0 3.2 3 Tabl e 5 . Result s o f

test s o f attainmen t

an dintelligenc e Variabl e N 

### S D Chronologica l ag e (months ) Reading — accuracy (months ) comprehensio n (months ) Spellin g (standar dscore ) Mathematic s (standar dscore ) WISC-R — verba l I Q performanc e I Q full scal e I Q 194 194 194 194 194 194 194 194 109.1 0

112.1 7 110.1 0 99.3 6 99.1 0 103.3 6 106.4 1 105.2 4 25.3 7

23.0 6 24.3 5 14.2 5 16.1 8 14.9 1 13.8 1 14.2 0 

### Blood-lead

concentrations Tabl e 2 show s th e distributio n o f th e first sampl e o f blood-lea dlevels . Th e mean o f 12.7 5 ug/100 m

l an dth e rang e o

f 7-2 4 ji g ar e both smalle r tha n thos e foun d i n th e pilo t

study . Tabl e 3 give s th e distributio n o f thi s sampl e b y social class . I n contras t t o several othe r

studies , includin g th e pilot , th e differenc e betwee n th e level s accordin g t o socia

l clas s wa s smal l an ddi dno t reac h statistica l significanc e at th e 0.0 1 level . Result s o f th e secon destimat e o

f blood-lea dar e given in Tabl e 4 . Th e mean concentratio n increase db y abou t 2ug , asomewha

t surprisin g figure, given tha t

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### Lea deffect s o n intelligenc

e attainmen t an dbehaviou r Tabl e 6 . Teachers ' rating s o

f behaviou r 22 9

Teacher s scale s Needlema n B scal e Conner s Boys ? 1.9 1 3.1 8 9.7 6 S D 2.3 4 3.9 7 10.9 1 Girl s X 1.0 4 2.1 3 6.5 4 S D

1.6 7 2.6 9 6.7 2 F rati o 8.5 7 4.5 7 5.9 3 P

0.0 1 0.0 1 0.0 5 

### th e childre n were almos t

2 year s olde r

an dbloo dlevel s usuall y decreas e wit h in
creasin g age . What

i s more , th e increas e i s almos t doubl e tha t

whic h migh

t hav e bee n expecte db y chance , given that , a s note dabove , ± 10 % i s excepted . Th e correlatio n o

f 0.5 4 betwee n th e tw o measure s wa s simila r t o tha t reporte db y Ewer s e t al . (1982) , suggestin g tha t th e ran k orde r o f th e childre n ma

y b e mor e stabl e tha n th e absolut e estimat e of bloo dlevel . Becaus e o

f a n uncertainty abou t

whic h wa s th e mor e vali destimat e for ou r purposes , analyse s wer e carrie dou t usin g bot h firs t

an dsecon destimate s an da n averag e o f th e two . Intelligence and

attainment Tabl e 5 indicate s tha t

th e result s o

f th e test s use dwer e what

woul db e predicte d for amainl y middl e clas s sample . Ther e wa s n o significan t differenc e betwee n th e result s o

f th e whol e sample , an d th e subsampl e comprisin g th e smaller , secon dbloo dlea dgroup . Behaviour

ratings Ver y fe w childre n wer e rate da s devian t o n an y item s b y parent s o r teachers . Tabl e 6 , a s well a s showin g se x difference , bear s ou t

th e low leve l o

f unaccepta bl e behaviou r

i n school . I t

shoul db e note dtha t

for th e Rutte r

B scale , acut-of

f scor e o f 9 i s generall y regarde da s indicatin g behaviou r disturbance . Social variables Th e pictur e obtaine dfromth e famil y intervie w wa s on e o

f astabl e group . I n 90 % o f th e sampl e th e natura l parent s wer e marrie dan d livin g together ; onl y 2 % o f th e familie s containe d4 o r mor e children ; 83 % o

f parent s owne dthei r ow n home s an d 44 % ha d bee n a t th e same addres s for

mor e tha n 8 years . Al l house s ha d basi c amenitie s an d ove r 90 % ha d thei r

ow n garden . Seventy-on e percen t o f mother s wer e o r

ha d bee n i n non-manual-labou r occupations , an d th e mean score s o f

both parent s o n th e WAI S subtest s wer e abov e average , bein g betwee n 11. 1 an d 12. 2 (th e averag e i s 10.0) . The association between lead, age, social class, IQ and

attainment Tabl e 7 show s th e result s o f analyse s o

f covariance ; th e first

lea destimat e i s use dan d th e grou p divide da t th e media n int o uppe r

an d lowe r

levels . Ther e wa s asocia

l clas s effect , a s expected , bu t n o lea deffect . 1 

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Tabl e 7 . Analyse s o f

covarianc e showin g adjuste dmeans—firs t blood-lea destimat e Pb B grou p 7-1 2 13.2 4 Ag e Social-clas s PbB l N

8 0 8 2 Accurac y

(months ) 114.5 3 111.5 1 P= 0.00 1 N S N S Comprehensio n

(months ) 112.7 7 109.3 3 P= 0.00 1 P = 0.0 2 N S Spellin g

100.7 2 98.6 1 N S N S Mathematic s

110.2 4 98.6 6 N S N S Verba l I Q

104.4 8 103.4 3 P= 0.00 1 N S Performanc e

108.2 0 106.3 2 i ° = 0.0 4 N S Full-scal e I Q

106.8 6 105.1 8 P = 0.00 1 N S



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### Lea deffect s on intelligenc e attainment an dbehaviou

r 23 1 Tabl e 8 . Multiple regression analyses : Log first blood-lea dwit h ag e an dsocia l clas s on I Q an

d attainment (N = 86 ) Dependen t

variabl e Accurac y (age ) Comprehensio n (age ) Spellin g (standar dscore ) Mathematic s (standar dscore ) Verba l I Q
Performanc e I Q
Full-scal e I Q Predicto r (i n orde r o f F value ) Ag e Social-clas s Lo g lea d Ag e Social-clas s Lo g lea d Social-clas s Lo g lea d Ag e Ag e Social-clas s Social-clas s Ag e Lo g lea d Social-clas s Lo g lea d Ag e Social-clas s Ag e Lo g lea d Coefficien t

of regressio n 0.6 4 -3.0 5 -8.0 0 0.6 9 -3.0 7 -3.6 5 -2.0 5 -4.5 7 -0.0 2 0.1 6 -1.5 3 -3.3 3 -1.1 0 1.9 1 -1.9 4 2.3 8 0.0 2 -2.9 4 -0.0 5 2.1 5 F

195.4 0 8.3 6 2.7 3 200.7 0 7.3 3 0.4 9 4.4 0 1.0 3 0.2 2 16.7 5 2.5 3 11.2 0 5.4 3 0.1 7 4.0 1 0.2 9 0.2 5 9.1 5 1.3 4 0.2 3 P

0.00 0 0.00 4 0.1 0 0.00 0 0.00 7 0.4 8 0.0 4 0.3 1 0.6 4 0.00 0 0.1 1 0.00 1 0.0 2 0.6 8 0.0 5 0.5 9 0.6 2 0.00 3 0.2 5 0.6 3 OIAR 2

0.5 6
0.5 5
0.0 3 0.0 9
0.1 0
0.0 2
0.0 6 

### A simila r patter n emerge dfromth e secon dan daverage dbloo dlea desti
mates . Tabl e 8 summarize s th e resul t of unforce dstep-wis e regressio n analyse s in which lead , socia

l class , an dag e ar e entere daccordin g t o th e proportio n o f varianc e accounte dfor

i n th e dependen t

variable . Simila r result s wer e obtaine dfor th e secon dan daverag e lea destimates . I n n o cas e doe s lea daccoun t for asignificant

amoun t o f residual varianc e in any o f th e measurement s o

f I Q o r attainment . Tabl e 9 give s aful

l scal e I Q result s for

th e firs t lea destimat e divide dint o manua l an dnon-manua l group s accordin g t o father' s occupation . I t wil l b e see n tha t ther e i s atren dtoward s a n effect i n manua l groups , bu t

thi s di dno t

reac h statistical significance , possibl y becaus e th e number s wer e relativel y small . Th e result s o f th e secon dan daverage destimate s wer e similar . ."-•.V'V.'lv
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### Lead and behaviour Wit h s o fe w childre n showin g sign s o f disturbe dbehaviour , i t

wa s no t surprisin g tha t n o significant

relationship s wer e foun dbetwee n lea dan dany o f th e ratings .P. 9

23 2 

### R . Lansdow n e t al . Tabl e 9 . Analyse s o

f varianc e dividin

g sample into manua

l an dnon-manua

l groups , usin

g approximat

e quartile s o

f P b distributio n



# IBIIft- f

Vf-''.' • '•' " Dependen t variabl e Non-manual

group Verba l I Q

Performanc e I Q

Full-scal e I Q

Manual group Verba l I Q

Performanc e I Q

Full-scal e I Q

Lea dgroupings : 1 =

1 1 = 

## m = I V = P b grou p N I I I II I I V I I I II I I V I I I II I I V
I I I II I 

# r v i i i 

### i n I V i 

# n i n 

# r v 2 8 2 6 2 7 2 1 2 8 2 6 2 7 2 1 2 8 2 6 2 7 2 1
1 6 2 5 2 1 2 5 1 6 2 5 2 1 2 5 1 6 2 5 2 1 2 5 7-10ug/100m l 11-1 2 ug/10 0 m

l 13-1 4 15-2 4 ug/10 0 m

l ug/10 0 m l Mea n 102.2 9 109.8 8 103.6 7 110.5 2 104.0 7 110.6 1 106.3 3 112.2 9 103.3 9 111.4 2 105.3 3 112.5 2
102.3 1 98.3 2 98.9 5 99.4 8 110.1 9 103.6 4 103.4 8 103.4 0 106.8 7 100.6 8 101.0 9 101.3 2 S D

16.5 7 14.5 5 14.3 9 15.2 5 13.1 3 15.9 9 15.1 8 9.6 5 13.5 2 14.9 4 15.0 3 12.8 1
12.5 4 9.3 0 14.7 4 16.0 9 13.5 9 14.6 5 10.9 7 14.6 3 12.9 8 11.4 8 13.1 6 15.7 3 F

1.9 3

1.8 5

2.5 2

0.3 1

1.0 4

0.8 3 P

0.1 3

0.1 4

0.0 6

0.8 2

0.3 8

- 0.4 8



### The association between lead and social variables Tabl e 1 0 summarize s individual item s correlatin g wit h lea dlevels . Ther e i s littl e consistenc y i n thes e findings . O f th e 1 3 item s foun dt o corre lat e significantly b y Smit

h e t al . (1983) 1 

### , onl y 7 i

n thi s stud y wer e foun dt o b e sig
nificantly associate dwit

h eithe r th e first o r secon dbloo dlevel s an donly tw o (pic aan dag e of

housing ) wit

h both .

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# r
Lea deffect s o n intelligenc e attainmen t an dbehaviou r 

### 23 3 Tabl e 10 . Paren t

interview : P b effects , firs t an dsecon dlea destimates . Spearma n correlation : P= 0.0 1 Pb l N = 19 4 Birthweigh t (i.e. , more norma l weigh t= Pb ) Typ e o f schoo l fathe r attende d ("better " schoo l = higher Pb ) Father' s personalit

y disorde r (mor e sever e disorde r = lowe r Pb ) Mother' s workin g hours week * (les s hours workin g = highe r Pb ) Thumb-suckin g Pica : pas tfor toy s pas tfo r earth * pas tduratio n fo r eart

h rs -0.1 8 0.1 7 -0.2 3 -0.1 9 0.2 7 0.1 7 0.1 9 0.1 9 Pb2/V=16 2 Metho d o f

delivery (i.e. , mor e norma

l delivery = highe r Pb ) Ag e a tweaning * (late r = highe r Pb ) Father' s occupation ; further education ; satisfaction wit

h outings alon e Mother' s occupation* — previous (includinghousewife) ; no w Total quarrels/bickerin g Family cleanlines s State o f insid e paintwor

k
Wor k o n car Terrace d hous e in area Frequency o f

fathe r playin g ou twit h child * Frequency o f

mothe r playin g ou twit h child * (i.e . les s outsid e pla

y = highe r Pb ) rs -0.1 9 0.2 0 0.2 1 -0.2 2 -0.1 8 0.2 3 0.2 3 0.1 9 0.2 4 0.1 8
-0.21 . -0.1 8 0.3 4 0.1 7

' Significan t

a t eithe r 0.0 1 o r 0.0 5 leve l fo r

bot h Pb l an dPb 2 

### Discussio n Th e overal l conclusio n fromthi s study i s tha t ther e i s n o evidenc e o

f asignifi
can t effect o f lea do n IQ , attainmen t

o r behaviou r

onc e othe r

variable s ar e accounte dfor . Th e secon dstudy wa s mor e sophisticate di n desig n tha n th e first

but , in th e event , th e additiona l informatio n wa s no t use dquit e a s ha dbee n intended . Th e uncertainty abou t

th e variation s in bloo dlea dlevel s mean t several analyse s ha d t o b e carrie dou t

in a n exploratory manner . Th e socia l dat awere satisfactory , bu t th e absenc e o

f any significant

relationshi p betwee n leadan dth e outcom e variable s mean t

tha t ther e wa s n o nee dt o invoke th e socia l informatio n s o laboriousl y collected . Th e failure t o replicat e th e result s o f th e first jtud y remain s t o b e explained . A possibl e explanatio n ma y b e foun din tha t

th e only immediatel y apparent dif
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### ference s betwee n th e tw o group s wa s i n th e socia

l compositio n o

f th e families : th e secon dcontaine dafa r greate r proportio n o

f middl e clas s parent s tha n th e first . A possibl e hypothesi s t o appl y t o th e result s o f th e first an d secon dstud y take n togethe r

i s tha t lea dmight

hav e an effec t

onl y whe n othe r

factor s leadin g t o disadvantag e ar e present . Some suppor t

fo r thi s argumen t

i s give n b y asuggestio n of arelationshi p betwee n lea dan d behaviou r in ou r secon dstudy bu t

onl y amongs t

working-clas s children . Furthe r

support i s given in th e wor

k o f Winnek e an d Kraeme r

(1984) , wh o analyse dthei r

dat at o fin

dtha t th e lea deffect

was , t o som e extent , stronge r i n thei r sociall y disadvantage dchildre n an d fromHarve y e t al . (1984 ) wh o re porte dindication s o

f simila r socia l clas s difference s in apparen t lea deffects . However , ther e i s at

th e momen t

n o mor e tha n asuggestio n tha t thi s i s likely t o b e asatisfactor

y explanatio n for

th e observe dfindings . Eve n i f on e allow s for

th e possibilit

y o f suc h socia

l factor s interactin g wit

h lead , ther e i s nothin g i n th e presen t stud y t o sugges t

tha t withi n normal , lo w level s o f exposur e lea dwil

l accoun t fo r mor e tha n 2%-3 % o

f th e varianc e i

n measure dintelligence , fa r les s tha n i s accounte dfor by geneti c an d othe r

en vironmenta l factors . Th e possibl e interactio n betwee n socia l variable s an dlea d discusse dabov e remain s worth y of furthe r consideration . Acknowledgements. Thi s researc h wa s supporte db y Medica l Researc h Council Specia l Pro
jec t Gran t G 80/11564 . Th e Inne r

Londo n Educatio n Authorit y an dth e teacher s i n th e school s concerne dar e thanke dfo r thei r kin dassistance . Reference s Conner s C K

(1969 ) A teache r

ratin g scal e fo r

us e i n dru g studie s with children . A mJ Psychiatr y 126:884-88 8 DHS S (1980 ) Lea dan dhealth . Th e repor t o f aDHS S workin g part y o n lea di n th e environ
ment . He r

Majesty' s Stationer y Office , Londo n Ewer s U , Winnek e G , Frei r I , Jerman n E , Kraeme r

U (1982 ) Lea di n deciduou s teet h o f chil
dre n livin g in anon-ferrou s smelte r are aan darura l are ao f th e FRG . In t

Arc h Occu p Enviro n Healt h 30:139-15 1 Harve y P G (1984 ) Lea dan d children' s health—recen t researc h an dfutur e questions . J Chil d Psycho l Psychiatry 25:517-52 2 Lansdow n R , Yul e W , Urbanowic z MA , Millar I B (1983 ) Bloo dlead , intelligenc e attainmen t an dbehaviou r

i n schoo l children : overvie w o f apilo t study . In : Rutte r

M , Russel l Jone s R(eds ) Lea dversu s health : source s an deffect s o f lo w leve l lea dexposure . Wiley , Chicheste r Neal e M D (1958 ) Neal e analysi s o f readin g ability . MacMillan , Londo n Needlema n HL , Gunno e C , Levito n A , Ree dR , Peresi e H , Mahe r C , Barret t

P (1979 ) De
ficit s i n psychologi c an d classroo mperformanc e o f childre n wit

h elevate ddentin e lea d levels . N Eng l J Me d300:689-69 5 Rutte r M , Yul e W (1968 ) Teachers ' ratin g scal e B(2) . Institut e o f Psychiatry , Londo n Rutte r M , Tizar dJ , Whitmor e K (1970 ) Educatio n healt h an dbehaviour . Longman , Londo n Smith M , Delve s T , Lansdow n R , Clayto n B , Graha mP (1983 ) Th e effect s o f lea dexposur e o n urba n children : th e Institut e o f Child/Southampto n Study . De v Me dChil dNeuro l [Supp l 47 ] vo l 2 5 Verno n P E (1977 ) Verno n grade dwor dspellin g test . Hodde r & Stoughton , Londo n Verno n PE , Mille r

R M (1976 ) Verno n grade darithmetic-mathematic s test . Hodde r & Stoughton , Londo n P.1 1

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Lea d effects o n intelligenc e attainmentan d behaviou r 23 5 Wechsle r D (1955 ) Th e Wechsle r adultintelligenc e scal e Psychological Corporation , Ne w York Wechsle r D (1974 ) Th e Wechsle r intelligenc e scal e for children - revise d Psychological Cor poration , Ne w Yor

k Winnek e G , Kraemer U (1984 ) Neuropsychological effects o f lead i n childre n interaction s wit h social background vanabl e Neuropsychobiolog y I I 195-20 2 Yul e W , Lansdown R , Milla r LB , Urbanowicz M

A (1981 ) Th e relationshi p betwee n bloo d lea d concentrations , intelligenc e an d attainmen tt

n a schoo l population , a pilo tstud y De v Me d Chil d Neuro l 23 567-57 6 Yul e W , Lansdown R tUrbanowic z MA (1982 ) Predictin g educational attainmentfro m WISC- Rin a primar

y schoo l sampl e B r J Clin Psycho l 3 1 43-4 6 Receive d June 19/Accepte d Octobe r 10 , 198 5

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