# OAR Box 1112 Prepped byRyan Dugan



### Document

Number: 

# 16 ) ll-B- 5 Docket Number: 

# A-83-2 2

Printed 4/16/2008 9:12:06

AM Sheet 16 of 97 P. 1P. 2

, _ _^ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y'H_-<IS > -S^ I ^SH%Z . ? WASHINGTON , D.C . 2046 0



## ^ U 3 

## 7-'^ 5 OFFICE O F POLICY , PLANNIN

GAN D EVALUATION

SUBJECT : LA

GTIM E INTH E RESPONS E O F BLOO D LEA D T O AI R LEA

D AND IT S IMPLICATION S FOR AVERAGIN GTIM E

FROM : Joe l Schwart z

Offic e o f PolicyAnalysi s

TO : Jef f Cohe n

Offic e o f Ai r Qualit yPlanning an d Standard s

Thi s mem o discusse s th e result s o f ou r analysi s o f th e lag tim e fo r change s i n ai r emission s t o sho wu p a s significan t change s i n bloo d lead . I n ou r analysi s o f th e NHANE S an d othe r dat a w e foun

d tha t ther e wa s a detectabl e lag structur e betwee n change s i n ai r lea

d an d change s i n bloo d lead levels . Thi s lag wa s als o foun

d i n th e Chicag o an d Ne wYor k screening program data , in th e CDC screening progra mdata , an

d wa s als o foun

d b y Rabinowit z e t al . i n thei r analysi s o f cord lead level s i n Boston . W e als o use d logisti c regressio n analysi s o f th e probabilit yo f childre n having highbloo d lead levels , an d foun d the sam e lag structure .

I n th e NHANE S analysis , variable s fo r gasolin e lead us e i nP. 3

the mont htha t th e individua l wa s examined , th e previou s month , the secon

d previou s month , an d th e thir d previou s mont hwer e considered . Whe n onl yon e o f thos e variable s wa s use d i n a regression , along wit hth e demographi c factors , th e previou s month s gasolin e lea d ha d th e highes t R 2 an d th e highes t t statistic . Th e third previou s month' s gasolin e lead wa s no t significant . Whe n al l thre e significan t variable s wer e entere d simultaneousl yth e regressio n di d no t becom e il l conditioned , an d the ratio' s o f th e regressio n coefficient s therefor e indicate d th e relativ e contribution s o f th e thre e month s gasolin e lea d variable s t o th e bloo d lead . Again , th e previou s month s gasolin e lead wa s mos t significant , an d ha d th e larges t coefficient . Th e curren t month' s an d secon d previou s month' s coefficient s wer e approximatel yequa l i n size , an d abou t hal f tha t o f th e previou s month' s coefficient . W e therefor e trie d a distribute d lag , creating a variabl e equa l t o 1/ 2 th e previou s month s gasolin e lea d plu s 1/ 4 th e curren t an d second previou s month s gasolin e lead , an d i t gav e an eve n bette r fit , confirmin g the fac t th e th e ratio' s w e foun d wer e showin g th e distributio n o f the rea l lags .

T o confirmwhethe r th e on e mont hlag fo r a significan t chang e in bloo d lea d showin g u

p wa s i n fac t correct , w e examine d the Ne wYork an

d Chicag o screening programs . W e onl yhad quarterl ydat a on bloo d lea d level s fo r thes e program s s o th e distribute d lag analysi s wa s unlikel yt o work , but , sinc e w e had monthl ygasolin e lea d us e i n th e SMSA's , w e coul d se e whethe r th eP. 4

• V

w e obtaine d a bette r fi t using th e sam e thre e month' s gasolin e lead , o r b

ylagging th e gasolin e lead b ya mont h(i.e . b

yusing December , January , an d Februarygaslead i n a regressio n fo r th e averag e bloo d lead i n January , February , an d March) . Th e on e mont hlagge d gasolin e lead gav e a highe r R 2 the n th e concurren t quarterl ygasolin e lead i n bot hcities . Rabinowit z e t al. , i n thei r analysi s o f cord lead an d gasolin e lead i n Boston , als o foun d tha t th e on e mont hlagge d gasolin e lea

d fi t thei r dat a better . Thu s four differen t dat a source s see

m t o confir

mth e same effect .

T o determin e whethe r th e prevalenc e o f highbloo d lead level s i s als o responsiv e t o mont ht o mont hchange s i n ai r lea d w e performe d logisti c regressio n analysi s o f th e probabilit yo f being abov e 3 0 ug/d l versu s gasolin e lead using th e NHANE S data . Onc e again , on e mont hlagge d gasolin e lead explaine d a highe r portio n o f th e variance , an d th e distribute d lag mode l gav e a n eve n bette r fit . T o confirmthes e result s i n anothe r dat a se t w e use d the CD C report s o f th e numbe r o f childre n screene d eac h quarte r fo r lead toxicity , an d th e proportio n tha t wer e foun d t o have lea

d toxicity . Again , on e mont hlagge d gasolin e lead gav e a bette r fi t than concurren t gasolin e lead i n explaining th e proportio n o f childre n tha t had lead toxicity . Thu s change s i n ai r lea d emission s produc e change s i n th e numbe r o f childre n wit h hig hbloo d lea

d levels , wit hth e greates t effec t showin g up abou t a mont hlatter . Thi s indicate s tha t ther e wil l b eP. 5

significan t change s i n th e numbe r o f childre n wit hhighbloo d lea d level s du e t o mont ht o mont hchange s i n th e ai r lea d concentration . Setting a monthl ystandar d woul d protec t agains t thes e increases . Obviously , thes e ar e childre n wh o wil l onl y spen d a mont ho r tw o wit hhig hbloo d lea d levels , s o th e healt h ris k i s les s tha n fo r childre n wh o spen d a considerabl e tim e a t highlevels , an

d therefor e th e healt hbenefit s ar e smaller ; howeve r th e cos t o f running th e complianc e monitor s mor e ofte n can' t b e tha t expensive , an d tha t seem s t o b e th e onl ything counterbalancing th e epidemiologica l evidenc e tha t thes e change s wil l occu r i n a month . Usin g a monthl ystandar d wil l als o d e fact o reduc e th e averag e ai r lead level , sinc e control s wil l b e installe d t o mee t standard s i n th e highemissio n months , an d tha t wil l bot hincreas e cost s t o industr yan d permanentl yreduc e th e numbe r o f childre n a t highbloo d lead levels . Tha t i s a separat e issue , sinc e o n average , th e sam e reductio n i n th e averag e numbe r o f childre n wit hhighbloo d lead level s can b e achieve d wit ha lowe r quarterl ystandard .