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Determining the Impacts on Human Health Attributable to Hazardous Waste Sites VERNON N. HOUK Center for Environmental Health, Centers for Disease Control, Atlanta, GA 30333

The Superfund Act and implementing E x e c u t i v e Order assign to the Department of H e a l t h and Human Services the responsibility for assessing the threat hazardous waste s i t e s pose to the h e a l t h of workers and the general p u b l i c . Our working definition for such a h e a l t h risk assessment i s the determination of probabilities of v a r i o u s adverse h e a l t h outcomes that r e s u l t or would r e s u l t from exposure to s p e c i f i e d hazards. To fulfill our l e g a l mandate, we intend first to determine the nature and q u a n t i t y of t o x i c m a t e r i a l s present at Superfund sites, the s i z e and p r o x i m i t y of potentially exposed human p o p u l a t i o n s , and the existence of likely pathways for s i g n i f i c a n t human exposure. I f all three f a c t o r s are present, a d d i t i o n a l study through v a r i o u s approaches, such as exposure documentation s t u d i e s , d i s e a s e - r e l a t e d epidemiologic s t u d i e s , or disease registries, will be considered.

I n December 1980, P r e s i d e n t C a r t e r s i g n e d i n t o l a w a b i l l known as t h e C o m p r e h e n s i v e E n v i r o n m e n t a l R e s p o n s e , Compensation and L i a b i l i t y A c t — m o r e commonly known as t h e S u p e r f u n d A c t . I t i s d e s i g n e d t o d e a l w i t h t h e b u r g e o n i n g p r o b l e m o f c l e a n i n g up o l d and abandoned h a z a r d o u s w a s t e s i t e s . The A c t imposes a t a x on t h e c h e m i c a l i n d u s t r y and t h e n a l l o c a t e s t h a t money, a l o n g w i t h a F e d e r a l and S t a t e c o n t r i b u t i o n , t o s i t e s n e e d i n g emergency r e s p o n s e o r l o n g - t e r m c l e a n u p ; a s s e s s m e n t o f h e a l t h e f f e c t s w h i c h may r e s u l t f r o m e x p o s u r e ; and e n f o r c e m e n t a c t i o n against p a r t i e s r e s p o n s i b l e f o r these s i t e s , i n c l u d i n g generat o r s , t r a n s p o r t e r s , and s i t e owners. O f f i c i a l s o f the E n v i r o n m e n t a l P r o t e c t i o n Agency (EPA) t e s t i f i e d b e f o r e C o n g r e s s t h a t EPA h a d i d e n t i f i e d o v e r 9,600 u n c o n t r o l l e d h a z a r d o u s w a s t e s i t e s , h a d made p r e l i m i n a r y a s s e s s m e n t s o f 6,100 o f t h e s e , and, b y J u l y 1981, h a d c o m p l e t e d 0097-615 6/82/0204-0021 $06.00/0 © 1982 American Chemical Society

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

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a l m o s t 2,800 o n - s i t e i n s p e c t i o n s , i n c l u d i n g some s a m p l i n g o f s i t e c o n t e n t s and g r o u n d and s u r f a c e w a t e r . The C e n t e r s f o r D i s e a s e C o n t r o l (CDC), an agency o f t h e P u b l i c H e a l t h S e r v i c e , h a s been a s s i g n e d t h e r e s p o n s i b i l i t y f o r implementing the h e a l t h - r e l a t e d portions of Superfund f o r the D e p a r t m e n t o f H e a l t h and Human S e r v i c e s . A l t h o u g h CDC h a s t h e p r i n c i p a l r o l e i n m e a s u r i n g t h e i m p a c t o r p o t e n t i a l i m p a c t on human h e a l t h w h i c h may be r e l a t e d t o e x p o s u r e , t h e N a t i o n a l T o x i c o l o g y P r o g r a m and t h e N a t i o n a l L i b r a r y o f M e d i c i n e h a v e a c t i v e r o l e s i n p r o v i d i n g u p - t o - t h e - m i n u t e i n f o r m a t i o n about t h e known h e a l t h e f f e c t s o f c h e m i c a l s o r c h e m i c a l c o m b i n a t i o n s f o u n d i n Superfund s i t e s . S i m i l a r l y , CDC s N a t i o n a l I n s t i t u t e f o r O c c u p a t i o n a l S a f e t y and H e a l t h w i l l h e l p e n s u r e t h a t t h e h e a l t h o f emergency p e r s o n n e l and c l e a n u p w o r k e r s i s p r o t e c t e d when they respond i n Superfund a c t i o n s . The tremendous number o f o r p h a n e d w a s t e s i t e s i n t h i s c o u n t r y r e f l e c t s t h e growth o f the s y n t h e t i c o r g a n i c c h e m i c a l i n d u s t r y ( F i g u r e 1 ) . I n 1940, a p p r o x i m a t e l y one b i l l i o n pounds o f s y n t h e t i c o r g a n i c c h e m i c a l s were p r o d u c e d i n t h e U n i t e d States. By 1965, t h i s q u a n t i t y had i n c r e a s e d n e a r l y a h u n d r e d f o l d and i t now e x c e e d s 300 b i l l i o n pounds a y e a r . T h i s e x p o n e n t i a l growth o f the i n d u s t r y has a worrisome byp r o d u c t i n t h e m a s s i v e p r o b l e m o f t o x i c w a s t e d i s p o s a l . To d e t e r m i n e i f s u c h w a s t e s c a u s e h e a l t h damage i n e x p o s e d human p o p u l a t i o n s , we must c o n d u c t e p i d e m i o l o g i c i n v e s t i g a t i o n s o f r e l a t i o n s h i p s b e t w e e n t o x i c e x p o s u r e and p o s s i b l e a d v e r s e h e a l t h outcome, c l i n i c a l o r s u b c l i n i c a l . I n c o n d u c t i n g human h e a l t h s t u d i e s b e f o r e S u p e r f u n d was e n a c t e d , we f o u n d t h a t s u c h i n v e s t i g a t i o n s a r e c o n c e p t u a l l y s i m p l e and i n v o l v e s t r a i g h t f o r w a r d c o n c e p t s o f c a u s e and e f f e c t . I m p l e m e n t i n g t h e s e s t u d i e s , however, i s " e a s i e r s a i d t h a n done." Because o f the e x t r e m e l y d i v e r s e s i t u a t i o n s i n which hazardous m a t e r i a l s a r e i n v o l v e d , each study presents unique problems. Table I i l l u s t r a t e s the d i v e r s i t y , both i n waste m a t e r i a l s and e x p o s u r e s e t t i n g s , o f e i g h t r e c e n t t o x i c w a s t e situations. D i f f e r e n c e s , i n f a c t , c a n be q u i t e l a r g e , r a n g i n g f r o m t h e common d r u m - f i l l e d dump s i t e t o t h e w i d e s p r e a d d i s p e r s a l o f waste m a t e r i a l . Some g e n e r a l i z a t i o n s , however, c a n be made about t h e s e k i n d s o f s t u d i e s . E p i d e m i o l o g i c s t u d i e s u s u a l l y c o n s i s t o f three fundamental phases: ( 1 ) D e t e r m i n i n g what t o x i c m a t e r i a l s a r e p r e s e n t , (2) e s t a b l i s h i n g how human e x p o s u r e t o t h e s e t o x i c m a t e r i a l s m i g h t o c c u r , and ( 3 ) m e a s u r i n g a c t u a l o r p o t e n t i a l b i o l o g i c effects. S u b s t a n t i v e i n f o r m a t i o n i n e a c h o f t h e s e phases i s e s s e n t i a l f o r s u c c e s s f u l l y c o m p l e t i n g any e p i d e m i o l o g i c s t u d y . The f i r s t s t e p i n any t o x i c w a s t e s t u d y i s t o d e t e r m i n e what t o x i c m a t e r i a l s a r e p r e s e n t and i n what amounts. Since most t o x i c w a s t e s i t u a t i o n s i n v o l v e t h e dumping o f d i v e r s e m a t e r i a l s , p r o b l e m s o f e x p e n s i v e t e c h n i c a l m e t h o d o l o g y c a n be formidable. However, w i t h o u t an a d e q u a t e i n v e n t o r y o f t h e 1

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

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Ηουκ

Impacts on Human Health

1915

1925

1935

1945 Year

1955

1965

1975

Figure 1. Historical growth of the synthetic organic chemical industry. (Repro­ duced from Ref. 15.)

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

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TABLE I

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R e c e n t S i t u a t i o n s I n v o l v i n g P o t e n t i a l Human Exposure t o P o t e n t i a l l y T o x i c Waste M a t e r i a l s Principal Routes of Potential Human E x p o s u r e

Location of S i t e

Toxic Materials

Physical Condition

L o v e C a n a l dump Niagara F a l l s , New Y o r k

Largely hydro­ carbon residues from p e s t i c i d e production

I n a c t i v e landf i l l i n resi­ d e n t i a l area

Direct, air­ b o r n e , and waterborne contacts

M e l v i n Wade dump, C h e s t e r , Pennsylvania

Diverse organic chemicals

Surface c o l ­ l e c t i o n waste i n drums i n urban s e t t i n g

Direct contact, e x p l o s i o n , and fire

Woburn, Massachusetts

A r s e n i c com­ pounds , h e a v y metals, organic chemicals

Abandoned waste lagoon with multiple s u r f a c e dumps

D i r e c t and waterborne contacts

Triana, Alabama

DDT and r e l a t e d compounds

Industrial w a s t e dumped in a rural stream

Food c h a i n (fish)

Βloomington, Indiana

Polychlorinated biphenyls (PCB s)

Direct contact Industrial waste contamiand p o s s i b l y nating municifood c h a i n p a l sewage u s e d f o r garden manure

T r i s t a t e Mining District, Oklahoma, K a n s a s , and Missouri

Heavy m e t a l s , acidic aquifer

Mine t a i l i n g s and a c i d i c aquifer recharge

Montgomery County, Pennsylvania

Trichlorethylene

Industrial D i r e c t and waste contamiwaterborne nating aquifer; contacts underground s t o r a g e tank rupture

Pittston, Pennsylvania

Chlorinated s o l v e n t s , HCN, and h e a v y metals

M i l l i o n s of g a l l o n s of w a s t e dumped i n t o abandoned mine s h a f t s

f

A i r b o r n e and irreparably contaminated aquifer

Food c h a i n and waterborne exposure

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

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c h e m i c a l s — t h e i r q u a l i t y and q u a n t i t y and t h e p h y s i c a l c o n d i t i o n s under which they are p r e s e n t — i t i s premature, i f not i m p o s s i b l e , t o d e s i g n adequate e p i d e m i o l o g i c s t u d i e s . I f o n l y low c o n c e n t r a t i o n s o r s m a l l amounts o f t o x i n s a r e p r e s e n t , t h e r e may not be s u f f i c i e n t r e a s o n t o p r o c e e d w i t h i n v e s t i g a t i o n s . The d e c i s i o n o f w h e t h e r t o p r o c e e d i s not a l w a y s s i m p l e , s i n c e p u b l i c c o n c e r n and p o l i t i c a l p r e s s u r e can be c o m p e l l i n g e v e n i n the absence o f a c o n f i r m e d t o x i c exposure. D e s p i t e such p r e s s u r e s , i t i s important to r e a l i z e t h a t c o n d u c t i n g even a simple survey o f h e a l t h e f f e c t s i s p e r i l o u s i f one l a c k s i n f o r m a t i o n about t o x i n s and e x p o s u r e , s i n c e few, i f any, m e a s u r a b l e h e a l t h e f f e c t s a r e s u f f i c i e n t l y s p e c i f i c f o r e x p o s u r e t o p a r t i c u l a r t o x i n s o r g r o u p s o f t o x i n s t o be s u r r o gates f o r d i r e c t l y measuring t o x i c exposure. A f t e r a s s e s s i n g t h e n a t u r e and q u a n t i t i e s o f t o x i n s p r e s e n t , one must e v a l u a t e t h e i r p o t e n t i a l f o r human e x p o s u r e . E v e n when m a t e r i a l s known t o be t o x i c a r e p r e s e n t , human e x p o s u r e may not h a v e o c c u r r e d o r may be o n l y r e m o t e l y p o s s i b l e . B e f o r e e x p o s u r e c a n be e v a l u a t e d , t h e means o f e x p o s u r e ( f o r e x a m p l e , d i r e c t c o n t a c t , c o n t a m i n a t e d w a t e r , o r c o n t a m i n a t e d a i r ) must be d e t e r m i n e d , and the s i z e o f human p o p u l a t i o n s p o t e n t i a l l y e x p o s e d and t h e i r d e g r e e o f p r o x i m i t y t o t h e t o x i c m a t e r i a l s must be defined. A n o t h e r r e a s o n one must c o n s i d e r the n a t u r e o f t h e c h e m i c a l s i n v o l v e d i s t h a t some c h e m i c a l s p a s s t h r o u g h t h e body q u i c k l y , whereas o t h e r s are s t o r e d i n t i s s u e . Exposure to c h e m i c a l s w h i c h p e r s i s t i n t i s s u e , s u c h as P o l y c h l o r i n a t e d B i p h e n y l s ( P C B ' s ) o r DDT, o f c o u r s e , p r o v i d e s much g r e a t e r o p p o r t u n i t y f o r p r o d u c t i v e epidemiologic study than exposure to t r a n s i e n t a g e n t s ( s u c h as t r i c h l o r o e t h y l e n e i n Montgomery C o u n t y ) . Many s t u d i e s a r e u n d e r t a k e n l o n g a f t e r a c t i v e e x p o s u r e has occurred. I n s u c h s t u d i e s , e x p o s u r e can be j u d g e d o b j e c t i v e l y by m e a s u r i n g l e v e l s of p e r s i s t e n t t o x i n s i n t i s s u e . The p r i m e o b j e c t i v e i n e p i d e m i o l o g i c s t u d i e s i s t o a s s o c i a t e p a r t i c u l a r e x p o s u r e s w i t h p o t e n t i a l h e a l t h e f f e c t s and t h u s t o d e f i n e c a u s e - e f f e c t r e l a t i o n s h i p s . S i n c e t h i s p r o c e s s i s an i n d i r e c t a s s e s s m e n t , i t i s h i g h l y d e p e n d e n t on t h e a c c u r a c y and s p e c i f i c i t y o f o b s e r v a t i o n s r e c o r d e d b o t h f o r e x p o s u r e and outcome. I t i s a more p o w e r f u l s t u d y i f d o s e - r e s p o n s e r e l a t i o n s h i p s c a n be shown, t h a t i s , i f i n c r e a s i n g l e v e l s o f e x p o s u r e are a s s o c i a t e d w i t h i n c r e a s i n g f r e q u e n c y of the h e a l t h e f f e c t s in individuals. To d e t e r m i n e t h i s c a u s e - e f f e c t r e l a t i o n s h i p , t h e e p i d e m i o l o g i s t must be aware o f f o u r d i f f i c u l t i e s w h i c h can l i m i t t h e power o f an e p i d e m i o l o g i c i n v e s t i g a t i o n ( T a b l e I I ) . The f i r s t i n v o l v e s t h e s i z e o f t h e p o p u l a t i o n needed f o r a s t u d y t o demons t r a t e a g i v e n h e a l t h e f f e c t w i t h a g i v e n d e g r e e o f power. This depends b o t h on t h e d e g r e e o f e x p o s u r e and on t h e e x p e c t e d b a s e l i n e frequency o f the p a r t i c u l a r h e a l t h e f f e c t . I f the

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

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RISK ASSESSMENT A T HAZARDOUS W A S T E SITES

TABLE I I E p i d e m i o l o g i c Issues Fundamental t o E v a l u a t i n g P o t e n t i a l T o x i c Waste H e a l t h E f f e c t s Epidemiologic

Issues

Impact on E p i d e m i o l o g i c

Study

Expected b a s e l i n e frequency of s p e c i f i c h e a l t h e f f e c t s

R e l a t i v e l y low expected f r e quency r e q u i r e s l a r g e p o p u l a t i o n f o r study, e s p e c i a l l y to detect small increases i n risk.

Latency

Long l a t e n c y may r e q u i r e p e r i odic or continuous long-term population followup.

period

Multiple causative factors (clinical nonspecificity)

Since p a r t i c u l a r health e f f e c t s are not o f t e n s p e c i f i c f o r p a r t i c u l a r t o x i c exposures, d a t a must b e c o l l e c t e d and evaluated.

A l t e r a t i o n of r o u t i n e l y c o l l e c t e d exposure and/or outcome i n f o r m a t i o n t o coincide

D i m i n i s h e s p r e c i s i o n o f exposure/outcome r e l a t i o n s h i p .

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

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h e a l t h outcome t o be measured i s r a r e , t h e p o p u l a t i o n t o be s t u d i e d needs t o be l a r g e . The s e c o n d d i f f i c u l t y i s t h a t o f l o n g o r v a r i a b l e l a t e n c y , t h e p e r i o d b e t w e e n e x p o s u r e and m e a s u r a b l e e f f e c t . At lower l e v e l s o f t o x i c e x p o s u r e , outcomes s u c h as c a n c e r may not o c c u r u n t i l years l a t e r . T h i s means t h a t t h e s t u d y d e s i g n must i n c l u d e long-term h e a l t h followup. The u s u a l r e c o m m e n d a t i o n i s t o e s t a b l i s h an e x p o s u r e r e g i s t r y , w i t h a 20- t o 2 5 - y e a r s t u d y . The a l t e r n a t i v e i s t o s t u d y c u r r e n t c a n c e r i n a p o p u l a t i o n known t o have been e x p o s e d o v e r a span o f y e a r s . Neither alternative i s e a s y s i n c e r e g i s t r i e s a r e e x p e n s i v e and c o m p l i c a t e d l o g i s t i c a l l y by t h e m o b i l i t y o f t h e U.S. population. The t h i r d d i f f i c u l t y i s t h a t o f c o m p e t i n g c a u s e s o r , expressed d i f f e r e n t l y , the c l i n i c a l n o n s p e c i f i c i t y o f the h e a l t h e f f e c t s under study. To t h e e p i d e m i o l o g i s t , t h i s means a d j u s t i n g f o r many p o t e n t i a l c o n f o u n d i n g f a c t o r s i n a s t u d y . The s t u d y d e s i g n must i n c l u d e c o l l e c t i n g d a t a on o t h e r e x p o s u r e s t h a t might a l s o cause the h e a l t h e f f e c t . I n p r a c t i c a l terms, t h i s means c o l l e c t i n g d a t a on p a s t o c c u p a t i o n a l e x p o s u r e s , p e r s o n a l e x p o s u r e s , s u c h as c i g a r e t t e s m o k i n g o r t h e use o f a l c o h o l o r d r u g s , and p e r s o n a l c h a r a c t e r i s t i c s , s u c h as s e x , r a c e , age, and s o c i o e c o n o m i c s t a t u s , w h i c h may p r e d i c t l e v e l s o f r i s k f o r s p e c i f i c d i s e a s e s t a t e s . The more v a r i a b l e s a s t u d y addresses, o f c o u r s e , t h e more c o m p l e x i t s e v e n t u a l a n a l y s i s and the g r e a t e r t h e s i z e o f the p o p u l a t i o n needed f o r a d e q u a t e l y assessing health effects. The f o u r t h d i f f i c u l t y — o n e o f t e n e n c o u n t e r e d — i s t h a t a h e a l t h outcome r o u t i n e l y m e a s u r e d by p o l i t i c a l b o u n d a r i e s ( c a n c e r m o r t a l i t y , f o r i n s t a n c e ) has t o be r e s h a p e d t o e n v i r o n m e n t a l b o u n d a r i e s , s u c h as t h o s e imposed by an a q u i f e r o r w i n d p a t t e r n , to i n c l u d e the p o p u l a t i o n under study. U n l e s s the e x p o s u r e o r outcome b o r d e r s a r e d e f i n e d by p r o p e r l y e x t r a p o l a t i n g o r i n t e r p o l a t i n g them t o c o i n c i d e g e o g r a p h i c a l l y , any cause-and-effeet relationship i s useless. S e v e r a l methods the e p i d e m i o l o g i s t has f o r i n v e s t i g a t i n g r e l a t i o n s h i p s v a r y g r e a t l y i n c o s t , t i m e and e n e r g y expended, and a n a l y t i c and i n t e r p r e t i v e v a l u e . The d e s c r i p t i v e s t u d y i s s i m p l y , as t h e name i m p l i e s , a s e r i e s o f r a t e s , r a t i o s , and p r o p o r t i o n s which h e l p d e s c r i b e e i t h e r the exposure or the outcome i n d e t a i l . The c a s e - c o n t r o l s t u d y i s r e l a t i v e l y e a s y t o c a r r y o u t , and new a n a l y t i c t e c h n i q u e s have a l r e a d y i n c r e a s e d i t s interpretive value. An e x p o s u r e s t u d y , a l t h o u g h not s t r i c t l y i n the r e a l m o f e p i d e m i o l o g y , documents e x p o s u r e i n v a r i o u s substrata of a population. The f o l l o w i n g t h r e e a c c o u n t s o f w a s t e - s i t e i n v e s t i g a t i o n s demonstrate f o u r major approaches to a s s e s s i n g h e a l t h e f f e c t s at hazardous waste s i t e s : (1) D e s c r i p t i v e s t u d i e s , ( 2 ) c a s e - c o n t r o l s t u d i e s , ( 3 ) s t u d i e s , and (4) c o h o r t s t u d i e s .

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Woburn, M a s s a c h u s e t t s Control Studies

SITES

- A n E x a m p l e o f D e s c r i p t i v e and C a s e -

D u r i n g t h e summer o f 1979, r e s i d e n t s i n t h i s e a s t e r n M a s s a c h u s e t t s town became c o n c e r n e d an a p p a r e n t c l u s t e r o f s i x l e u k e m i a c a s e s , d i a g n o s e d s i n c e 1969 i n c h i l d r e n o f f a m i l i e s l i v i n g i n a 6-block area i n the southeastern p o r t i o n o f t h e town (1970 t o t a l p o p u l a t i o n : 3 7 , 0 6 7 ) . The c l u s t e r was r e p o r t e d t o t h e M a s s a c h u s e t t s D e p a r t m e n t o f P u b l i c H e a l t h (MDPH) a n d t o t h e C e n t e r s f o r D i s e a s e C o n t r o l (CDC) b o t h by l o c a l c i t i z e n s and a B o s t o n p h y s i c i a n . C o n c e r n was a l s o e x p r e s s e d r e g a r d i n g o t h e r cancers, e s p e c i a l l y kidney cancer. An a s s e s s m e n t o f t o w n - s p e c i f i c c a n c e r m o r t a l i t y r a t e s made i n d e p e n d e n t l y by MDPH a t a b o u t t h e same t i m e f o r t h e 1969-1978 d e c a d e i n M a s s a c h u s e t t s showed s t a t i s t i c a l l y s i g n i f i c a n t e l e v a t i o n s i n Woburn f o r a l l c a n c e r s , as w e l l as f o r s e v e r a l s p e c i f i c k i n d s o f c a n c e r . The c o n c e r n about e x c e s s c a n c e r s f o c u s e d on p o s s i b l e c a u s e s r e l a t e d t o t o x i c w a s t e d i s p o s a l s i t e s i n t h e town. From t h e m i d - 1 9 t h c e n t u r y u n t i l t h e 1 9 2 0 s , Woburn h a d b e e n a m a j o r c e n t e r f i r s t f o r c o m m e r c i a l t a n n i n g o f h i d e s and l a t e r f o r chemical production o f lead a r s e n i c a l p e s t i c i d e s . Efforts i n t h e 1970 s t o d e v e l o p an i n d u s t r i a l p a r k i n t h e n o r t h e a s t e r n p a r t o f t h e town u n c o v e r e d s e v e r a l o l d abandoned w a s t e d i s p o s a l s i t e s containing hides or chemicals r e l a t e d to p r i o r i n d u s t r i a l activities. Among t h e t o x i c c h e m i c a l s f o u n d i n e x c e s s i v e amounts were a r s e n i c , l e a d , chromium, and cadmium. C o n c e r n about l e a c h i n g of waste chemicals i n t o d r i n k i n g water l e d t o e x t e n s i v e t e s t i n g o f w e l l s w h i c h s u p p l y t h e town's w a t e r . Two o f 11 s u c h w e l l s showed e x c e s s i v e l e v e l s o f v a r i o u s o r g a n i c c h e m i c a l s ( t r i c h l o r o e t h y l e n e , f o r example). These two w e l l s h a d s u p p l i e d w a t e r , p r i n c i p a l l y t o t h e e a s t e r n h a l f o f t h e town, s i n c e t h e m i d 1960 s and were l o c a t e d a s h o r t d i s t a n c e t o t h e n o r t h o f t h e leukemia c l u s t e r neighborhood. Because o f t h e demonstrated c h e m i c a l l e v e l s , t h e w e l l s were c l o s e d i n 1979. To e x p l o r e t h e p o s s i b l e c a u s e o f r e p o r t e d c a n c e r e x c e s s e s , and p a r t i c u l a r l y t o examine t h e p o s s i b l e r e l a t i o n s h i p between t h e town's t o x i c w a s t e s i t u a t i o n and t h e c h i l d h o o d l e u k e m i a c a s e c o n c e n t r a t i o n , MDPH and CDC, i n 1980, c o n d u c t e d a j o i n t s t u d y . I n c i d e n c e p a t t e r n s f o r s e l e c t e d t y p e s o f c a n c e r were s t u d i e d by u s i n g d a t a c o l l e c t e d from l o c a l and r e g i o n a l h o s p i t a l s o u r c e s . I n c r e a s e d f r e q u e n c i e s f o r c h i l d h o o d l e u k e m i a and f o r k i d n e y c a n c e r were c o n f i r m e d , w i t h t h e c h i l d h o o d l e u k e m i a e x c e s s b e i n g l o c a t e d i n one p a r t i c u l a r c e n s u s t r a c t . S h i f t i n g e p i d e m i o l o g i c g e a r s t o c a s e - c o n t r o l methods, i n v e s t i g a t o r s then obtained a d d i t i o n a l data r e g a r d i n g a wide range o f p o s s i b l e e n v i r o n m e n t a l causes through d e t a i l e d i n t e r views w i t h p a t i e n t s o r r e l a t i v e s o f p a t i e n t s . F o r a l l 12 c h i l d hood l e u k e m i a c a s e s i n t h e town, t h i s p r o c e s s i n c l u d e d i n t e r v i e w s w i t h two a g e - and s e x - m a t c h e d c o n t r o l s drawn from s c h o o l e n r o l l ment l i s t s — o n e f r o m t h e m a t c h e d c a s e n e i g h b o r h o o d , t h e o t h e r f

1

1

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

3.

Ηουκ

Impacts on Human Health

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f r o m a n o t h e r p a r t o f t h e town. No c a u s a l f a c t o r s were f o u n d from t h e s e i n t e r v i e w d a t a f o r e i t h e r k i d n e y c a n c e r o r l e u k e m i a . F o r l e u k e m i a i n p a r t i c u l a r , no c l e a r - c u t d i f f e r e n c e s were s e e n i n r e s p o n s e s p r o v i d e d by c a s e and c o n t r o l f a m i l i e s . The l i m i t a t i o n s o f t h e s e o b s e r v a t i o n s c a n be d e s c r i b e d i n terms o f t h e g e n e r a l p r o b l e m s a s s o c i a t e d w i t h s u c h t o x i c w a s t e studies. The h e a l t h outcome o f c o n c e r n ( c a n c e r , s p e c i f i c a l l y c h i l d h o o d leukemia) i s a r e l a t i v e l y r a r e disease. The t o x i c chemical exposure of p a r t i c u l a r persons h a v i n g these d i s e a s e s c o u l d n o t be d i r e c t l y documented, s i n c e t h e o r g a n i c c h e m i c a l s f o u n d i n w e l l w a t e r were t r a n s i e n t . T h e r e f o r e , no means were a v a i l a b l e f o r l i n k i n g p a r t i c u l a r leukemia cases to p a r t i c u l a r t o x i c s u b s t a n c e s . F o r t h e p r e s e n t , t h e n , we a r e l e f t w i t h an a p p a r e n t l e u k e m i a c a s e c l u s t e r and no good e v i d e n c e f o r a s s o c i a t i n g cases w i t h the s t r i k i n g e n v i r o n m e n t a l t o x i c waste p r o b l e m s c l e a r l y p r e s e n t i n t h e town. T r i a n a , Alabama - An E x a m p l e o f a C r o s s - s e c t i o n a l

Study

T r i a n a , w i t h a p o p u l a t i o n o f 600, i s l o c a t e d a t t h e c o n f l u e n c e o f I n d i a n C r e e k and t h e T e n n e s s e e R i v e r . From 1947 u n t i l 1971 DDT was m a n u f a c t u r e d i n a p l a n t 10 k i l o m e t e r s f r o m Triana. S e v e r a l t h o u s a n d t o n s o f DDT i n d u s t r i a l w a s t e accumu­ l a t e d i n the sediments of a t r i b u t a r y o f I n d i a n Creek. Locally c a u g h t f i s h have had t o t a l DDT r e s i d u a l l e v e l s up t o 100 t i m e s t h e t o l e r a n c e o f 5 p a r t s p e r m i l l i o n (ppm) s e t by t h e Food and Drug A d m i n i s t r a t i o n . The h i g h l e v e l s o f DDT r e s i d u e s i n t h e 12 p e r s o n s s u r v e y e d w e r e s u s p e c t e d o f r e s u l t i n g f r o m t h e i r c o n s u m i n g f i s h w h i c h had a c c u m u l a t e d DDT f r o m s e d i m e n t s . The t a s k a t hand was t o measure r e s i d e n t s ' e x p o s u r e t o DDT and r e l a t e i t , i f p o s s i b l e , to h e a l t h e f f e c t s i n the p o p u l a t i o n — a n example o f a c r o s s - s e c t i o n a l s t u d y . Of t h e 518 p e r s o n s p a r t i c i p a t i n g i n t h e s t u d y , i n c l u d i n g 44 c o m m e r c i a l f i s h e r m e n and t h e i r f a m i l i e s , 96.3 p e r c e n t gave b l o o d specimens. The mean serum DDT l e v e l (76.2 p a r t s p e r b i l l i o n ( p p b ) ) o f 499 p e r s o n s l i v i n g downstream f r o m t h e DDT m a n u f a c t u r i n g p l a n t was about f o u r t i m e s t h e n a t i o n a l mean (16.7 p p b ) . The number o f p a r t i c i p a n t s w i t h h i g h serum l e v e l s o f DDT was s m a l l , and t h e r e f o r e no sound c o n c l u s i o n s c o u l d be drawn from the s t u d y , r e g a r d l e s s of the time i n v o l v e d . On t h e o t h e r h a n d , t h e p o p u l a t i o n was l a r g e enough f o r t h e s t u d y t o i n c r e a s e u n d e r s t a n d i n g on s e v e r a l p o i n t s — n a m e l y , t h a t DDT a p p e a r s t o a c c u m u l a t e w i t h age, t h a t t h e l i v e r i s a f f e c t e d , and t h a t serum t r i g l y c e r i d e s and c h o l e s t e r o l l e v e l s a r e r e l a t e d t o DDT l e v e l . F u r t h e r , i n t h e c i t i z e n s o f T r i a n a , l e v e l s o f PCB's i n serum were f o u n d t o c o r r e l a t e p o s i t i v e l y w i t h b l o o d p r e s s u r e c e r t a i n l i v e r f u n c t i o n t e s t s , and c h o l e s t e r o l , i n d e p e n d e n t l y o f age and s e x .

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HAZARDOUS W A S T E SITES

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B u c k s and Montgomery C o u n t y , P e n n s y l v a n i a - An E x a m p l e o f a P o t e n t i a l Cohort Study I n May 1979, t h e P e n n s y l v a n i a D e p a r t m e n t o f H e a l t h r e p o r t e d t h a t s e v e r a l p u b l i c and p r i v a t e w a t e r s u p p l i e s i n Montgomery C o u n t y , P e n n s y l v a n i a ( p o p u l a t i o n 627,600) were c o n t a m i n a t e d w i t h t r i c h l o r o e t h y l e n e (TCE). TCE was f o u n d i n 70 o f 100 w e l l - w a t e r s u p p l i e s i n Rahns, P e n n s y l v a n i a . Ten o f t h e s e p o s i t i v e s a m p l e s showed l e v e l s o f TCE i n e x c e s s o f 500 ppb, and 5 s a m p l e s showed TCE i n e x c e s s o f 1,000 ppb. The s u s p e c t e d s o u r c e o f c o n t a m i n a t i o n was a s t e e l w i r e and r o d m i l l t h a t u s e d t h i s compound as a d e g r e a s i n g agent. I m p r o p e r d i s p o s a l r e s u l t e d i n s p i l l s on p l a n t p r o p e r t y , w h i c h l e a c h e d i n t o n e a r b y l a g o o n s and w e l l w a t e r s u p p l i e s . A t a n o t h e r t u b e company, a p i p e f e e d i n g a l a r g e s t o r a g e t a n k o f TCE r u p t u r e d and s p i l l e d o v e r 2,000 g a l l o n s o f TCE i n t o a s t o r m sewer, r e s u l t i n g i n f u r t h e r c o n t a m i n a t i o n o f s u r f a c e and g r o u n d w a t e r . A p p a r e n t l y , h u n d r e d s o f p e o p l e were b e i n g e x p o s e d t o TCE through t h e i r d r i n k i n g water. No a c u t e i l l n e s s had been r e p o r t e d t o be r e l a t e d t o t h e c o n t a m i n a t e d w e l l w a t e r , b u t C o n g r e s s i o n a l r e q u e s t s and a h i g h d e g r e e o f c o n c e r n f r o m c i t i z e n s and l o c a l o f f i c i a l s led to f u r t h e r study. Seven ( 6 % ) o f 117 r e s i d e n t s s c r e e n e d f o r t r i c h l o r o metabol i t e s had d e t e c t a b l e l e v e l s o f t r i c h l o r o e t h a n o l and t r i c h l o r o a c e t i c a c i d i n t h e i r u r i n e . The a p p r o a c h u s e d i n t h i s i n v e s t i g a t i o n was t o s p e c i f i c a l l y compare d e a t h s f r o m l i v e r c a n c e r i n Montgomery C o u n t y w i t h s u c h d e a t h s i n u n e x p o s e d p o p u l a t i o n s w i t h i n t h e same c o u n t y as t h e p r i m a r y c o m p a r i s o n g r o u p and w i t h p o p u l a t i o n s r e p r e s e n t e d by S t a t e and n a t i o n a l d a t a as a l t e r n a t e comparison groups. To a c e r t a i n d e g r e e , t h i s s i t u a t i o n l e n d s i t s e l f t o a p r o s p e c t i v e c o h o r t s t u d y . Had t h i s e p i d e m i o l o g i c t o o l b e e n e m p l o y e d , a d i s c r e t e p o p u l a t i o n o f e x p o s e d , and p e r h a p s u n e x p o s e d , i n d i v i d u a l s w o u l d have been r e g i s t e r e d , w i t h a p p r o p r i a t e i d e n t i f i e r s , and a s s i g n e d a p a r t i c u l a r e x p o s u r e level. T h i s p o p u l a t i o n w o u l d t h e n be a c t i v e l y f o l l o w e d f o r a minimum o f 15 t o 20 y e a r s , and v i t a l s t a t u s and any d e s i g n a t e d a d v e r s e h e a l t h outcomes w o u l d be r e c o r d e d and compared w i t h t h e S t a t e o r n a t i o n a l r a t e s f o r t h e same e v e n t . Obviously, a very l o n g t i m e i s r e q u i r e d and f o l l o w u p i s v e r y e x p e n s i v e . However, i n f o r m a t i o n o b t a i n e d f r o m a p r o s p e c t i v e c o h o r t s t u d y w h i c h i s w e l l d e s i g n e d and m e t i c u l o u s l y c o n d u c t e d c a r r i e s tremendous w e i g h t when one i s b a l a n c i n g i n f o r m a t i o n f r o m l e s s powerful i n v e s t i g a t i v e t o o l s . These p r o s p e c t i v e c o h o r t s t u d i e s must be w e l l t h o u g h t o u t , and t h e r e s h o u l d be a r e a s o n a b l e p o s s i b i l i t y f o r f u n d i n g through the l i f e of the study. An a l t e r n a t i v e t o t h e p r o s p e c t i v e c o h o r t s t u d y i s t h e r e t r o s p e c t i v e cohort study, i n which a defined population w i t h a p a s t e x p o s u r e has an e x i s t i n g m e a s u r a b l e h e a l t h outcome. The p a s t e x p o s u r e needs t o be w e l l documented so t h a t a g i v e n l e v e l o f e x p o s u r e c a n be a s s i g n e d t o e a c h i n d i v i d u a l i n t h e p o p u l a t i o n .

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

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3.

HOUK

Impacts on Human Health

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T h i s , o f c o u r s e , r e q u i r e s a c c u r a t e and a c c e s s i b l e e x p o s u r e r e c o r d s w h i c h c a n be r e a d i l y c o u p l e d t o t h e p o p u l a t i o n b e i n g viewed r e t r o s p e c t i v e l y . Thus, we have t h r e e s i t u a t i o n s i n w h i c h f o u r d i f f e r e n t e p i d e m i o l o g i c a p p r o a c h e s c o u l d be u s e d t o i n v e s t i g a t e h e a l t h e f f e c t s a s s o c i a t e d w i t h h a z a r d o u s w a s t e s i t e s o r any e n v i r o n mental contamination. I n summary, w i t h t h e i n c r e a s i n g p u b l i c c o n c e r n about t o x i c w a s t e s g r o w i n g o u t o f s u c h i n c i d e n t s as L o v e C a n a l , i t i s incumbent upon t h e F e d e r a l Government t o t r y t o answer t h e public's question: "How i s my h e a l t h , and t h a t o f my f a m i l y , a f f e c t e d by e x p o s u r e t o t o x i c w a s t e s ? " I f I c a n l e a v e y o u w i t h o n l y one message, i t i s t h a t t h i s q u e s t i o n i s e x t r e m e l y d i f f i c u l t t o answer. As I have shown t h e e p i d e m i o l o g i s t o r t h e i n v e s t i g a t o r c a n t a k e any one o r s e v e r a l o f v a r i o u s a p p r o a c h e s t o t h e s t u d y o f p o s s i b l e h e a l t h e f f e c t s from exposure t o t o x i c substances a t a g i v e n dump s i t e o r c h e m i c a l s p i l l . Each approach has i t s s t r e n g t h s and w e a k n e s s e s . S i m i l a r l y , e a c h dump s i t e o r s p i l l has i t s p e c u l a r i t i e s . We a r e i n t h e p r o c e s s o f m a t c h i n g what i s known about t h e p r i o r i t y s i t e s t o be c l e a n e d up u n d e r t h e S u p e r f u n d l a w w i t h t h e b e s t a p p r o a c h t o l e a r n i n g about t h e p o s s i b l e h e a l t h e f f e c t s on exposed people l i v i n g around those sites. Once we have s o r t e d o u t t h e s i t e s most l i k e l y t o g i v e us a n s w e r s about h e a l t h e f f e c t s and have d e s i g n e d t h e b e s t r e s e a r c h s t r a t e g y f o r s t u d y i n g e a c h s i t e , we c a n b e g i n o u r work i n t h e field. T h i s work p r o m i s e s t o be d i f f i c u l t and c o m p l e x , b u t we hope i t w i l l r e s o l v e t h e s e p u b l i c h e a l t h c o n c e r n s . Literature 1.

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C a r t e r , C . D . ; Kimbrough, R . D . ; Liddle, J.Α.; C l i n e , R.E.; Zack, M . M . , J r . B a r t h e l , W.F.; K o e h l e r , R.E.; Phillips, P . E . T e t r a c h l o r o d i b e n z o - d i o x i n : An a c c i d e n t a l poisoning episode in horse arenas. S c i e n c e , 1975, 188, 738-740. Dunphy, J.H.; Hail, A. Waste d i s p o s a l : It's a dirty b u s i n e s s . Chemical Week, March 1, 1978, pp. 25-29. Brown, C . C . Mathematical aspects of dose response s t u d i e s i n carcinogenesis: The concept of t h r e s h o l d s . Oncology, 1976, 32, 62-65. Dunphy, J.H.; Hall, A . Waste d i s p o s a l : S e t t l i n g on safer solution for chemicals. Chemical Week, March 8, 1978, pp. 28-32. Guess, H.; Crump, K.; P e t o , R. U n c e r t a i n t y estimates f o r low-dose-rate e x t r a p o l a t i o n s of animal c a r c i n o g e n i c i t y d a t a . Cancer Research, 1977, 37, 3475-3483. H o e l , D . G . ; G a y l o r , D.W.; Kirschstein, R.L.; Saffiotti, U.; Schneiderman, M . A . ; E s t i m a t i o n of risks of irreversible delayed toxicity, J . Tox. & Env. H e a l t h , 1975, 1, 133-151. Johnson, C . J . Toxic s o l u b l e waste d i s p o s a l in a s a n i t a r y landfill site d r a i n i n g to an urban water s u p p l y . AJPH, 1977, 67, 468-469 K r e i s s , K.; Zack, M . M . ; Kimbrough, R . D . ; Needham, L.L.; Smrek, A.L.; Jones, B . T . C r o s s - s e c t i o n a l study of a community w i t h e x c e p t i o n a l exposure to DDT. JAMA, 1981, 245, 1926-1930. Schmahl, D. Combination e f f e c t s i n chemical carcinogenesis (experimental results). Oncology, 1976, 2 3 , 73-76. W o l f f , A.H.; Oehme, F.W. Carcinogenic chemicals in food as an environmental i s s u e . JAVMA, 1974, 164, 623-629. "Chemical and Health Report, 1973," United States I n t e r ­ n a t i o n a l Trade Commission Reports on P r o d u c t i o n and Sale of S y n t h e t i c Organic Chemicals, 1918-1976.

RECEIVED July 16,

1982.

Long and Schweitzer; Risk Assessment at Hazardous Waste Sites ACS Symposium Series; American Chemical Society: Washington, DC, 1982.