1 7 7
Cad . Saúd e Púb lic a, Rio de Jane iro , 14(Sup. 3):177-179, 1998 OPIN IÃO O P I N I O N
M easuring exposure to
o rganochlorinated pesticides
Me d ind o a e xp o siç ão a p e stic id as
o rg a n o c l o r a d o s
1 De p a rt am en to de Ep i d e m i o l o g i a ,
In st i tu t o d e M ed icin a So cia l, Un i v ersid a d e d o Est a d o d o Rio d e Ja n e i ro.
Ru a São Fran cisco Xa vier 524 , 7oa n d a r. Ri o d e Ja n e i ro, R J 2 0 5 5 9 - 9 0 0 , Bra s i l . g u l n a r @ u e r j. b r
2 In st it u t o N acion al d e Cân cer. Av. Ven ezu ela 134, R io d e Ja n e i ro, R J 2 0 0 8 1 - 3 1 0 , Bra s i l .
Gu ln a r Az e v ed o e Si l v a M en d on ça 1 , 2
Abst ract En v i ro n m e n t a l ep i d em io l ogi ca l i n v est i ga t io n s i n ca n cer re m a i n , w i t h ra re ex c e p -t i o n s , i n c o n c l u s i ve . T h e d if ficu l-t ies of es-t a bli sh in g p a -t -t ern s o f m ea su rem en -t s o f ex p o s u re i n -t h e h u m a n bod y i s on e of t h e li m it a t ion s of t h ese st u dies. Th e fin di n gs of six recen t ep id em iological st u d ies t h a t a n alyz ed t h e a ssociat i on bet w een orga n o ch lorin at ed com p o u n d s a n d brea st ca n cer a re re v i ew ed in con sid erin g t h e p rob lem s of m ea su rin g en v iron m en t a l ex p o s u re t h ro u gh b iolo gi-ca l m ark e r s . Th e ep id em i ologigi-ca l ev iden ce b ased o n t h ese st u dies do n ot in d igi-ca t e a risk of bre a s t ca n ce r rela t ed t o orga n o ch lori n es. So m e a sp ect s t h a t m a y p a rt i a lly ex p la in t h is a bsen ce o f risk a re d iscu ssed re g a rd in g t h e i n v est iga t io n of en v iron m en t a l ca rcin ogen i c a gen t s in p op u la t io n s w i th low bu t h o m ogen eou sly sp rayed lev els o f ex p o s u re .
Key words Brea st N e o p l a s m s ; Pe s t i c i d e s ; En v i ro n m en t al Ex p o s u re
Resumo As in v est iga çõ es ep i dem io lógica s sobre câ n cer a m b ien t a l p erm an ecem , com ra ra s ex -c e ç õ e s , i n -c o n -c l u s i va s . As di fi-cu ld a d es em se est a b ele-cerem p a d rões d e m en su ra ção d e ex p o s i ç ã o n o corp o h u m a n o sã o a lgu m a s d a s lim it a ções d esse s est u d os. Os a ch a d os d os seis est u d o s ep i-d em iológicos recen t es qu e a n a lisa ra m a a ssocia çã o en t re com p o st os organ o clo rai-d os e câ n cer i-de m a m a fora m re v i s t o s , c o n s i d e ra n d o os p ro blem a s d e se m ed i r a ex p osi çã o a m bi en t a l p or m eio d e m a rc a d o res bi ológi cos. A ev id ên ci a ep id em iológica com ba se n esses est u d os n ã o i n di ca risco d e câ n cer d e m a m a rel a ci on a d o a o rga n o clora d o s . Algu n s a sp ect os q u e p o d em , p a rc i a l m e n t e , ex p l i ca r essa a u sên cia d e ri sco sã o d iscu t i d o s co n si d era n d o- se a i n v est i ga çã o d e a gen t es ca r-cin ogên icos a m bien t a is em p op u la ções co m n íveis de ex p osiçã o ba ixo s , p orém h om o gen eam en t e d i s s e m i n a d o s .
MEND O NÇA, G . A. S.
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Cad. Saúde Púb lica , Rio d e Jane iro , 14(Sup. 3):177-179, 1998
B a c k g ro u n d
En v i ro n m e n t a l e p id e m iological in ve s t i g a t i o n s in ca n ce r rem a in , wit h ra re e xc e p t i o n s, in co n -c l u s i ve. On o n e sid e, t h e re is n o sin gle a gen t in t h e e n viro n m e n t t h a t m ay b e h a rm fu l; on t h e o th er sid e, th e effe ct s ha ve , in ge n eral, lon g p e-rio d s o f in d u ct io n in vo lvin g co m p le x in t e ra c-t ion s b e c-twee n en viro n m en c-ta l a n d h o sc-t fa cc-t ors. H u m an d a t a lin kin g e n vir on m e n t a l a ge n t s t o h u m a n c a n c e r a re r a re ly a va i l a b l e . Re c e n t l y, e n v i ro n m e n t a l e p id e m io lo gy h a s la rge ly fo -cu se d on ch em ica l a n d p h ysica l age n ts su ch a s vo la t ile o r ga n ic c o m p o u n d s, m e t a ls, p a rt i c u -lat e m att e r, p est icid es an d ra d i a t i o n s.
In con t rast to en viron m e n t a l ep id e m iology in o cc u p a t io n a l s t u d y gro u p s o f w o rke rs t h a t a re e xp o s e d t o ch e m ic al a n d p h ys ica l a ge n t s, in ge n e ra l, th e re a re h igh e r le ve ls if co m p are d t o o n e co m m u n it y. It is p oss ib le t o c le a rly d e -fin e b e t w e e n e xp o s e d a n d n o t e xp o s e d in d i-v i d u a l s , as w e ll a s d ii-vid e t h e e xp o se d gr o u p wit h in t h e ca t e go r i ze d le ve ls o f in d ivid u al e x-p o s u re.
In o rd e r t o d isc u s s th e p r ob le m s o f m e a -s u r in g o n e e n viro n m e n t a l e xp o-s u re t h r o u g h b io logic al m ar k e r s, t h e e p id e m io lo gic al st u d -ie s t h a t a n a lyz e d t h e a sso c ia t io n b e t we e n o rg a n o c h l o r in a t e d co m p o u n d s an d ris k o f b re a st can ce r we re re v i e w ed a s an exa m p le.
O rganochlorines and breast cancer
Ex p e rim en ta l evid en ce sh ows t h a t org a n o c h l o -r in e s wit h xe n o e st -ro ge n p -ro p e -rt ie s a ct as ca - r-cin ogen s in a n im a ls (Da vis e t a l., 1993). Th e b i-o li-o gica l h yp i-o th esis relat in g i-o rg a n i-o c h l i-o rin es t i-o b re a st ca n ce r is b a s e d m a in ly o n t h e ir p e rs is-t e n c e in is-t h e e n viro n m e n is-t a s c o n is-t a m in an is-t s, t h a t h ad b e en alrea d y id e n tified in fish , h u m an t i s s u e , b lo od a n d m ilk, a n d in t h e ir e st ro g e n i c a c t i v i t y. Hu m a n e xp osu re t o t h ese com p o u n d s h a p p e n s in ge n e ra l t h ro u gh o u t co n t a m in e d foo d , a n d in s p e c ia l a n im a l p r o d u c t s. T h e s e c o m p o u n d s a ccu m u la te in a d ip ose t iss u e an d p e rsist fo r d e ca d e s, b e in g s lo wly e xc re t e d t h ro u gh fe ce s, u rin e a n d la ct a t io n (Ro ga n e t a l., 1986). T h ro u gh a n a lyt ic ch e m is tr y p ro c e -d u re s, re s i-d u e le ve ls o f t h e se c om p o u n -d s c an b e d e t e c t e d in s e ru m o r a d ip o se t is s u e w it h h igh sp ecificit y (Ku tz et al., 1991). Alt ho u gh th e u se o f D DT [2,2- b is(p c h l o ro p h e n y l ) 1 , 1 , 1 -t ri c h l o ro e -t h a n e ] a n d o -t h e r s o rg a n o c h l o ri n e s e m p l o ye d a s p e st ic id e s in a gr i c u l t u re wa s b an n e d in in d u st r i a l i ze d c ou n t ri e s, t h e y a re s t ill e xp o rt e d an d u s e d in o t h e rs d e ve l o p i n g c o u n t r ies w it h in a d e q u a t e p ro t e ct io n (Dich e t
a l., 1997). In So u t h Am e rica , t h e y we re la rg e l y u se d un til re cen tly in vector con t rol p ro g ra m s.
M easuring serum levels of organochlorine re s i d u e s
Du r in g t h e la s t five ye a r s s ix e p id e m io logic a l st u d ie s (t h re e in th e Un it e d St a t e s, o n e in Eu -ro p e , o n e in Me xico a n d o n e in Bra zil) we re co n d u ct e d in o rd e r t o a n a lyze t h e a sso c ia t io n b e t we en re sid u e s o f org a n o c h l o rin es in se ru m or a d ip o s e t is su e a n d b re a s t ca n c e r ( Wolff e t al., 1993; Krie ge r e t a l., 1994; Va n’t Ve e r e t al., 1997; Ló p e z - Ca r rillo e t al., 1997; Hu n t er et a l., 1997; Men d on ça , 1997). On ly Wolff e t a l. (1993) fo u n d a p o sit ive associa tio n . In th e ir stu d y, t h e m e an s e ru m co n ce n t ra t ion o f DDE (d ich loro -d i c h l o ro p h e n yl e t h yle n o ) wa s sign ific an t ly h igh e r a m o n g ca se s t h a n a m o n g co n t ro ls a n d t h e o d d s r a t io o f b r e as t c a n c e r, a ft e r a d ju st -m e n t fo r p o ssib le co n fo u n d e rs, o f w o-m e n at u p p er q u in tile co m p ared t o t h e lowest q u in tile was 3.68 (95% CI 1.01-13.50).
In five st u d ie s, t h e m e a n le ve ls o f D DE m e a s u red in ser um or ad ip ose t issu e fro m con -t rol su b je c-t s va ried from from 2.5 -t o 7.7 n g/ m L. Th e st u d y o f Kr ie ge r e t a l. (1994), wh ic h a n a -l y zed org a n o c h -l o rin e re sid u e s in st o re d se ru m sam p le s o f a ca se -co n t rol n este d t o a co h o rt o f 57,040 wom en , sh owed a m ean DDE le vel (43.1 n g/ m L) five t o n in e t im e s a s h igh a s t h o se in th e o t h ers stu d ie s, n e ve rth e le ss n o associa tio n wa s fo u n d . Th e se h igh se r u m le ve ls o b s e rve d ca n b e exp lain ed b e cau se a ll sam p les we re col-le ct ed b e fo re th e re s t rict io n for DDT com m ercia l u se , wh e n le ve ls o f e xp o s u re w e re co n se -q u en t ly h igh e r.
Th e resu lts o f t h e se st u d ie s are m u ch m o re ap p lica b le t o p op u lation s wit h low leve ls o f exp o s u re. Th e e exp id e m iolo gic e vid en ce co n ce rn -in g t h e re la t io n b e t we e n o r g a n o c h l o r-in e s a n d b re a s t c an ce r m ay s e e m in co n clu sive, a n d so m e a sp e c t s m a y p a rt ia lly e xp lain t h is. Fi r s t , th e le ve ls t h a t t h e org a n o c h l o rin e re sid u e s a re c u r re n t ly d e t e ct e d a t ar e t o o we a k t o le a d t o a n y effe ct (Ad a m i e t al., 1995). In exp eri m e n t a l re s e a rc h t h e gr ow t h of m a m m a r y t u m o r s in m a le r a t s w a s p ro m o t e d a ft e r a n in t a ke o f 25 m g/ kg/ d a y in t h e d ie t (Sc rib n e r & Mo t t e t , 1981). Seco n d , t h e e xp osu re is alm o st h om o ge n e o u s ly sp ra ye d a m o n g co n t ro l a n d ca se s u b -je ct s a n d o n ly a sm all p e rc e n t o f t h e s t u d ie d po p u la t ion s ha d u n d et ect a b le le vels o f DDE in s e ru m or a d ip o se t issu e.
Cad. Saúde Púb lic a, Rio de Jane iro , 14(Sup . 3):177-179, 1998 Th e a b se n ce o f a n a d e q u a t e gra d ie n t o f e xp o
-s u re ca n u n d e re -s t im a te t h e e ffe ct . Th e e p i-d e m iolo gic e vii-d e n ce b as e i-d o n t h e re f e r re i-d stu d ie s is n o t su fficien t to e xclu d e th e po ssib il-it y t h a t D DE c o u ld sh ow a re a l r isk fo r b re a s t ca n ce r at h igh e r le vels o f e xp osu re. In e xp o se d p o p u l a t i o n s, su ch a s fa rm e rs an d p est icid e a p p l i c a t o r s, t h e risk m a y b e d ifferen t. Wh en expo
-O R G A N -O C H L -O R I N ATED PESTICIDES 1 7 9
R e f e re n c e s
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