p. 1



# OAR Box 

# 1112

Prepped by RyanDugan



### Document

Number: 

# 18 ) ll-B- 7

Docket Number: 

# A-83-2 2

Printed 4/16/2008 9:12:06

AM Sheet 18 of 97P. 2

I X^mi I

UNITE

D STATES ENVIRONMENTA L PROTECTIO

N AGENC

Y 77

^ n 

## \~>** 

## SEPA 

## 198 5

SUBJECT : Modelin g th e bloo d lea d distributio n i n childre n FROM i Joe l Schwart z

Offic e o f

Polic y Analysi s To : Jef f

Cohe n Offic e o f

Ai rQualit y Plannin g an d Standard s Thi s mem o i s t o repor tth e result s o f reapplyin g th e technique s o f

m y previou s mem o o n modelin g th e bloo d lea d distributio n afte rtakin g int o accoun tth e CASAC' s reques tt o onl y conside rthos e childre n tha tca n realisticall y b e helpe d b y a n ai rqualit y standard . Th e implicatio n o f tha tstatemen twa s tha tCASA C fel ttha t ther e wer e som e childre n whos e bloo d lea d level s wer e s o hig h tha tchange s i n ai rlea d woul d no tb e important . I ti s no t obviou s wha tbloo d lea d cutof f t o use . sinc e t o adequatel y defin e "help " w e nee d t o kno w mor e abou tth e doe s respons e relationshi p o f lea d tha n w e do . Fo rinstance , reducin g achild' s bloo d lea d leve l fro m 50ug/d l t o 40ug/d l wil l stil l leav e i tabov e an y acceptabl e level , bu ttha tchang e ma y produc e a s much healt h improvemen tfo rtha tchil d a s movin g anothe rchil d fro m 25ug/d l t o 15ug/dl , an d ma y produc e mor e healt h improvement . I ti s certainl y possibl e tha tmovin g achil d fro m 120ug/d l t o llOug/d l wil l produc e n o noticeabl e healt h improvement , an d onl y majo r reduction s matte ra ttha tlevel . Pickin g th e poin ta twhic h tha t occur s i s mostl y a n exercis e i n judgment . Moreover , th e implication s o f changin g lo g bloo d lea d whil e leavin g th e GS

D fixe d i s tha tchange s i n bloo d lea d ar e proportionate . Tha tis , achang e tha treduce s a child' s bloo d lea d fro m 2 5 t o 2 0 ug/d l woul d b e expecte d t o reduc e achil d a t5 0 ug/d l t o 40ug/dl . I ti s ver y likel y tha tth e healt h benefi to f

th e latte requal s o rexceed s th e healt h benefi to f th e former . Th e constan tproportionat e reductio n implici ti n th e lognorma l distributio n ha s suppor ti n biolog y (beside s th e obviou s suppor ttha tth e distributio n i s i n fac tlognormal) . Th e childre n wit h hig h bloo d lea d level s ar e mor e likel y t o includ e thos e wit h highe rtha n averag e gu tabsorptio n rates . an d highe rtha n averag e pic aactivity . Seducin g ai r contaminatio n o f

dir tan d dus tb y 10 % shoul d produc e a10 % reductio n i n thei rabsorptio n fro m tha tmedia , jus ta s i tdoe s f o rth e lo w absorptio n an d lo w pic a children . However , tha t wil l resul ti n agreate rabsolut e decrease . I f w e interpre tth e CASA C statemen tt o onl y exclud e thos e childre n fo rwhom ther e wil l b e n o noticeabl e improvement , tha n i twoul d b e reasonabl e t o exclud e onl y thos e childre n abov e 7 0 ug/dl . Al l o f

ou rNHANES analyse s hav e exclude d al l indivic 'P. 3



### wit h bloo d lea d level s ove r7 0 ug/dl , s o m y previou s mem

o cover s tha tcase . O n th e othe rhand , we migh tinterpre tth e CASA C commentt o mea n tha ti f

childre n ar e a tbloo d lea d level s wher e w e canno t substantiall y affec tth e numbe ro f childre n a tthos e levels , tha t w e shoul d therefor e ignor e the m fo rth e airlea d standard ; Again , w e nee d t o decid e wha tsuc h aleve l is . In ou ranalysi s o f th e NHANE S dat aw e performe d logisti c regression s o f th e probabilit y o f childre n bein g abov e variou s level s a s afunctio n o f gasolin e lead , amajo rsourc e o f ai remissions . Gasolin e lea d wa s a statisticall y significan tpredicto ro f bloo d lea d level s bein g abov e 3 5 ug/dl , s o th e uppe rcutof f fo rimpac to f

airlea d mus tb e highe rtha n that . Th e lowes treasonabl e numbe ri s 4 0 ug/dl , s o I use d tha ti n th e nex tse to f runs . I exclude d al l childre n ove r4 0 ug/d l an d remove d th e effec to f

gasolin e lea d broadenin g th e distributio n b y adjustin g everyone' s bloo d lea d t o zer o gasolin e lead . I the n droppe d th e gs d b y 15% o f

th e fal l produce d b y removin g th e broadenin g du e t o gasolin e lea d t o accoun tfo rth e 15 % o f NHANE S airlea d tha t wa s no tgasolin e lead . Excludin g childre n ove r40ug/d l give s a gs d i n lo g spac e o f .3502 , compare d t o .36 0 a tzer o airlea d wit h th e childre n ove r4 0 ug/d l bu tbelo w 7 0 ug/d l included . Th e comparabl e gsd' s i n norma l spac e ar e 1.41 9 excludin g th e childre n abov e 4 0 ug/d l an d 1.4 2 8 includin g them . Thi s i s th e rang e tha tseem s mos tappropriate .