r/- : . i /•.*; . u,. j . «i i,E N V I R O N M E N T A L P R O T E C T I O N A G E N C Y

W A S H I N G T O N . D C 2046021 1330

T M t A O M I N I H T K A T Q H(oD6M

S U B J E C T ;

FROM

T O ;

Risk Ass e s smen t Forum Report on Revised Diox in T o x i c i t yEquival ency F a c t o r sF . H e n r y H a b i c h t I IChairRisk A s s e s s m e n t Counci' iA s s i s t a n t A d m i n i s t r a t o r sRegional A d m i n i s t r a t o r s

I n t r o d u c t i o nThe a t tached Risk Asse s sment Forum report p r e s e n t s interimt o x i c i t y equivalency f a c t o r s ( T E F s ) f o r chlor inated dibenso-d i o x i n s and - f u r a n s (CDDs and CD/ a) for use in al l Agencyo f f i c e s . As a 1989 u p d a t e to the 1987 Risk Ass e s smen t Forump a p e r on TEFs, th i s report a d d r e s s e s an issue that i s f a c e d , atone time or another, by all EPA program and regional o f f i c e s , byother f e d e r a l agenc i e s , and by s ta te and na t i ona l governments asw e l l . E P A ' s l e a d e r s h i p o f t h e movement f o r i n t e r n a t i o n a l l yc on s i s t en t TEFs, which ia de s cr ibed in the Forum r e p o r t , requiresA g e n c y - w i d e cons i s t ency as w e l l . A c c o r d i n g l y , the RiskA s s e s s m e n t Counci l recoanends u n i f o r m EPA use o f the interim TEFvalues in this Forum report, unless f o r m a l l y exempted .by theCouncil .T h i s memorandum prov id e s background i n f o r m a t i o n on the basisfor and use of the TEF approach and its role in risk assessment.I m p l i c a t i o n s f o r A g e n c y program o f f i c e s a n d procedures f o r RiskA s s e s s m e n t Counci l review of p o s s i b l e e x c ep t i on s are a l sod i s cu s s ed .BackgroundC h l o r i n a t e d d i b enzo-p-d i ox in s a n d d i b e n z o f u r a n s ( C D D s / C D F s )con s t i tu t e a f a m i l y of 210 s t r u c t u r a l l y re la ted chemicalcompounds . During the la t e i970s and early 1980s, EPA was f a c e dwi th numerous cases of environmental p o l l u t i o n involving CDDs andC D F s , e.g., emiss ions f r o m combustion sources, i n i t i a l l y ,concern was f o c u s e d s o l e l y on 2 , 3 , 7 , 8 - t e t r a c h l o r o d i b e n z o - p - d i o x i n( 2 , 3 , 7 , 8 - T C D D ) , which was produced p r i m a r i l y as a low levelb y p r o d u c t d u r i n g th e m a n u f a c t u r e o f certain herb i c id e s .

During the past 20 years, many s tud i e s have described thetox i c e f f e c t s o f 2 , 3 , 7 , 8 - T C D D . A l t h o u g h many ques t ions remain t obe answered, d a t a show that 2 , 3 , 7 , 8 - T C D D produc e s a varie ty oftoxic e f f e c t s , i n c l u d i n g cancer and r eproduc t iv e e f f e c t s , inl a b o r a t o r y an imal s at very low doses . W h i l e some r e p o r t s sugges tthat th i s chemical produc e s s i m i l a r e f f e c t s in humans, th i squestion is s e r i ou s ly deba t ed and more d e f i n i t i v e i n f o r m a t i o n ise x p e c t e d f r o m e p i d e m i o l o g i c a l s tud i e s current ly in progre s s .For risk assessment p u r p o s e s , EPA c l a s s i f i e s 2 , 3 , 7 , 8 - T C D D a sa "B2" carcinogen with a po t ency of 1.6 x 10 ( m g / k g / - d ) M , by farthe most po t ent carcinogen yet evaluated by the A g e n c y . Thechemical is a l s o the most p o t e n t r e p r o d u c t i v e toxin yet evaluat edby the A g e n c y , wi th a R e f e r e n c e Dose (RfD) of 1 p g / k g - d .C u r r e n t l y , the A g e n c y o f t e n c o n f r o n t s s i t u a t i o n s in whichc o n c e n t r a t i o n s of some of the 209 other CDDs/CDFs . g r e a t l y exceedthat of 2 , 3 , 7 , 8 - T C D D . Example s include exposure to CDD/CDFi m p u r i t i e s in t e chnical p e n t a c h l o r o p h e n o l , CDD/CDF residues atc er ta in s u p e r f u n d s i t e s , and CDD/CDF emiss ions f r o m certaincombus t i on sources. Much less is know about the t o x i c i t y ofthe s e congener s , but a v a i l a b l e i n f o r m a t i o n shows cause forconcern for some others. For e x a m p l e , a mixture o f 1 , 2 , 3 , 6 , 7 , 8 -and 1 , 2 , 3 , 7 , 8 , 9 - h e x a c h l o r o d i b e n z o - p - d i o x i n (HxCDD) has been shownto bo carc inogenic in labora tory an imal s when admini s t e r ed at lowdose s f o r a l i f e t i m e .W h i l e da ta a v a i l a b l e f r o m long-term in vivo s tud i e s do notexist f or th e m a j o r i t y o f CDDs/CDFs, a much larger body o f da tais a v a i l a b l e on short-term jjj vivo s tud i e s and a variety of invitro s t u d i e s . T h e s e e xp er imen t s cover a wide variety of endp o i n t s e .g. , d e v e l o p m e n t a l t o x i c i t y , c e l l t r a n s f o r m a t i o n , andenzyme i n d u c t i o n (aryl hydrocarbon h y d r o x y l a s e [ A H H ] ) . . W h i l e t h edoses necessary to e l i c i t a toxic re sponse d i f f e r s in each case,the r e l a t i v e p o t e n c y of the d i f f e r e n t compounds (compared to2 , 3 , 7 , 8 - T C D D ) i s g e n e r a l l y consi s tent f r o m one e n d p o i n t toanother. T h i s general cons i s t ency o f r e la t ive p o t e n c y f or th esame compounds across several e n d p o i n t s is the empirical basisf o r t h e T o x i c i t y Equivalency F a c t o r ( T E F ) concept f o r C D D s / C D F s .A p l a u s i b l e common xnechani s ia-o f-ar t prov ide s a d d i t i o n a ls c i e n t i f i c ra t i ona l e to the approach.

TBPThe t o x i c i t y equivalency f a c t o r method is an interimproc edure for a s s e s s ing the risks as soc iated with exposure toc o m p l e x mixtures o f CDDs and CDFs, Thf t method r e l a t e s th et o x i c i t y o f t h e 2 1 0 structure ' l y r e la t ed chemical p o l l u t a n t s t oeach o ther, u t i l i z i n g the l i m i t e d da ta bass of in vivo and invitro t o x i c i t y t e s t i n g . By r e l a t i n g the t o x i c i t y of tha 209 CDDsand CDFs to th e h i g h l y s t u d i e d 2 , 3 , 7 , 8 - t e t r a c h l o r o d i b e n z o - p -

- 3 '

d i o x i n " ( 2 , 3 , 7 , 8 - T C D D ) , t h e a p p r o a c h s i m p l i f i e s t h e asses sment o fri sks i n v o l v i n g expo sure to o i x ture s of CDDs and C D F s , such asinc inera tor f l y ash, hazardou s was te s , contaminated s o i l s , a n db i o l o g i c a l media.During the l a t e 1970s and ear ly 1980s, various r e g u l a t o r yagenc i e s in the U n i t e d S t a t e s , C a n a d a , and E u r o p e , d e v e l o p e dt h e i r own TEF schemes. As a r e s u l t , numerous s l i g h t l y d i f f e r e n tTEF methods ex i s t ed vhich c o s p l i c a t e d communication amongs c i e n t i s t s and agencies in a d d r e s s i n g the t o x i c o l o g i c a ls i g n i f i c a n c e o f c o m p l e x mixtures o f CDDs and CDFs.T h e Ri sk A s s e s s m e n t F o r u m - R e p o r t sW o r k i n g f r o m p r e l i m i n a r y ana ly s e s by EPA and others c i e n t i s t s , i n 1987 E P A ' s Risk A s s e s s m e n t F o r u m issued a reporto u t l i n i n g the TEF concept and recommending use of . the m e t h o d , onan in t er im bas i s , in EPA risk as se s sments invo lv ing CDDs andC D F s . U p o n recommendation o f t h e Risk A s s e s s m e n t C o u n c i l , t h eA g e n c y f o r m a l l y a d o p t e d t h i s interim T E F procedure ( E P A - T E F / 8 7 ) ,which has been used by EPA p r o g r a m o f f i c e s and the Regions ina d d r a s s i n g a variety of s i t ua t i on s of environmental contaainat ioni n v o l v i n g CDDs a n d C D F s . T h e E P A - T E F / 8 7 m e t h o d , p u b l i s h e d a s" I n t e r i r a Procedures f o r E s t i m a t i n g Risks A s s o c i a t e d withE x p o s u r e s t o M i x t u r e s o f C h l o r i n a t e d D i b e n z o - p - d i o x i n s andD i b e n z o f u r a n s (CDDs and CDFs)," has been w i d e l y a d o p t e d and i sr e p u b l i s h e d in the a t ta ch ed r epor t . In the 1967 r e p o r t , theA g e n c y e m p h a s i z e d that the method was inter im in nature, urgedc o l l e c t i o n o f more d e f i n i t i v e e x p e r i m e n t a l d a t a , and, inp r e s e n t a t i o n b e f o r e t h e S A B , committed i t s e l f t o p e r i o d i c reviewsas a d d i t i o n a l t o x i c i t y da ta were g enera t ed .F o l l o w i n g p u b l i c a t i o n of the 1987 r e p o r t , the Agency led as i x -na t i on p r o j e c t under the au sp i c e s of NATO vhich was aimed ata d o p t i n g a common se t o f TEFs to p r o m o t e in t ernat ionalc on s i s t ency in a d d r e s s i n g contaminat ion invo lv ing CDDs and CDFs,The new Forum r e p o r t , "1989 U p d a t e to the I n t e r i m Procedures forE s t i m a t i n g Risks A s s o c i a t e d with Exposures to M i x t u r e s o fC h l o r i n a t e d Dibenzo-p-Diox in s and -Dibenzo furan s (CDDs andC D F s ) " , s i g n a l s E P A ' s a d o p t i o n o f t h e N A T O I n t e r n a t i o n a l T E F s / 8 9(I-TEFs/89) as revision to the TEFs current ly in use. The newreport pr e s en t s the ra t i ona l e , m e t h o d o l o g y , and t o x i c i t y dataused to de t ermine the new values and describes d i f f e r e n c e sbetween the 1987 and 1989 schemes.Tha I - T E F s / 8 9 represent an improvement in an a l r eady u s e f u lrisk assessment t oo l . However , tho a p p r o a c h remains interim innature and should be r ep la c ed as soon as p o s s i b l e , through theresearch o u t l i n e d in the report. S p e c i f i c a l l y , the c o m p l e t er e p l a c e m e n t of any TEF method by a f o i o a s s a y method a p p e a r s to bef e a s i b l e w i th in th e near f u t u r e i f s u f f i c i e n t research resources

-4-

are d i r e c t e d at the p r o b l e m . U n t i l such research da ta aret o t a l l y d e v e l o p e d , the TEF a p p r o a c h shou ld be cont inued to berevised as new d a t a are d e v e l o p e d .i m p l i c a t i o n s f o r E P A ProgramsAs part of the Risk Asse s sment Forum examinat ion of therevised m e t h o d , EPA program and regional o f f i c e s most l i k e l y tob e i m p a c t e d ( e . g . , O S W E R , O P T S , O W , a n d Regions I I I , V , a n d I X )were asked to review and comment on any p o t e n t i a l p o l i c yi m p l i c a t i o n s f o r their programs . S p e c i f i c a l l y , these o f f i c e swere asked to a p p l y both the old and the new methods to c o l l e c t e dd a t a and to a n a l y z e the p o l i c y i m p l i c a t i o n s o f a d o p t i n g therevised scheme.It a p p e a r s that the new I-TEF/89 method is u n l i k e l y tos e r i o u s l y a l t e r assessment procedure s f o r most CDD/CDF mixture-The most s i g n i f i c a n t change in the u p d a t e d method (compared tothe e x i s t i n g EPA-TEF/87 scheme) is the as s ignment of more ' i g j -for the higher ch lor ina t ed CDDs and CDFs (hexa- h e p t a - , ana octa-s p e c i e s ) based upon s c i e n t i f i c da ta gathered in the past twoy e & r s .I n g e n e r a l , f o r many s a m p l e s ( e . g . , emi s s ions f r o mi n c i n e r a t o r s , p u l p a n d p a p e r m i l l s , b i o l o g i c a l s p e c i m e n s ) t ox i ce q u i v a l e n t s c a l c u l a t e d by the I - T E F s / 8 9 method w i l l be increasedby l e s s than a f a c t o r of two re lat ive to the e x i s t i n g EPA method.H o w e v e r , for some sources in which the h igher c h l o r i n a t e d s p e c i e sp r e d o m i n a t e ( e . g . , soil contaminated with CDDs and CDFs inp e n t a c h l o . r o p h e n o l ) , the t o x i c equ iva l en t s c a l c u l a t e d by therevi s ed scheme wi l l b e s i g n i f i c a n t l y higher. For e x a m p l e , f orsoil s a m p l e s taken around a p e n t a c h l o r o p h e n o l wood treatmentf a c i l i t y i n Region I I I a n d current ly l i s t e d o n t h e N P L ' , t h e toxicequ iva l en t s derived f r o m the I - T E F s / 8 9 are almost two orders ofm a g n i t u d e higher than those c a l c u l a t e d f r o m the E P A - T E F s / 8 7 bythe e x i s t i n g method. A l t h o u g h increases such as these may -resultin a d d i t i o n a l c l eanup requirements for some s i t e s , it is nota n t i c i p a t e d that the revised method w i l l add new s i te s to the

N P L .C o u n c l l _ & G t l o n

The Risk Asse s sment Council recommendation f or u n i f o r mA g e n c y - w i d e use of the TEF values in the Forum report is baaed ontwo cons iderat ions . F i r s t , f or CDDs and CDFs the TEF procedurep r o v i d e s a s p e c i f i c interim s o lu t i on for a common risk assessmentprob l em: cr i t i ca l g a p s in a data base, c oup l ed with a need tof i l l t h e g a p s with r a t i o n a l , t e c h n i c a l l y based a s s u m p t i o n s inorder to make r e g u l a t o r y dec i s ions . In th i s case, i f tha TEFmethod were not a v a i l a b l e (or if i t i s not u s e d ) , A g e n c y o f f i c e swould be f o r c e d to r e ly on random ad hoc a p p r o a c h e s or to

c

-5-

p o s t p o n e d e c i s i o n s , of course, as e m p h a s i z e d in the Forumr e p o r t / users must u n d e r s t a n d that the TEF values are based oni n c o m p l e t e da ta and that science p o l i c y c o n s i d e r a t i o n s h e l p e ds h a p e the numerical e s t imat e s . W h e n users a p p r e c i a t e theu n c e r t a i n t i e s a s s o c ia t ed with risk e s t imat e s based on TEFs, theTEFs are an a p p r o p r i a t e and u s e f u l t emporary s o l u t i o n to thep r o b l e m o f m i s s i n g d a t a f o r thi s p a r t i c u l a r c la s s o f chemicals .S e c o n d ; because o f s c i e n t i f i c uncer ta int i e s , t h e TEFm e t h o d o l o g y could wel l l ead to a j u s t i f i a b l e range of TEF valuesf or a given congener. For EPA, however, u s e o f d i f f e r e n t TEFvalues in d i f f e r e n t o f f i c e s would be an i n e x p l i c a b l e d e p a r t u r ef r o m E F A ' s l e a d e r s h i p o f t h e two-year e f f o r t t o d e v e l o pcons i s t ent in t e rna t i ona l values and me thod s for CDDs and CDFs.I n g e n e r a l , u n i f o r m A g e n c y p o l i c y a n d p r a c t i c e s f o r a s s e s s ingCDDs/CDFs .outweighs any i n d i v i d u a l p r e f e r e n c e f o r a m a r g i n a l l yd i f f e r e n t value in a p a r t i c u l a r EPA o f f i c e .The Counci l recognizes that new d a t a or spec ialc ircumstance s may j u s t i f y e x c e p t i o n s or new revisions to the I-T E F s / 8 9 . A n y A s s i s t a n t o r Regional A d m i n i s t r a t o r m a y a p p l y f o re x e m p t i o n f r o m thi s agency-wide requirement through a memorandumto the Chairman of the Risk A s s e s s m e n t Council e x p l a i n i n g (1) th»p r o p o s e d change in an I-TEF/89 value f o r any congener, (2) t h es c i e n t i f i c d a t a or r a t i o n a l e u n d e r l y i n g th e request , and (3) anyr e l a t e d program management c o n s i d e r a t i o n s .

A t t a c h m e n tc c : W i l l i a m K . R e i l l yRisk A s s e s s m e n t Counci lRisk Ass e s smen t Forua

Federal Ratater / Vol M. No. 214 / T u e s d a y . N o v e m b e r 7. 1983 / Nobce i 487E7Ctt!fOUCorpontJon/Dov*'t Gulf$*fic*. tt a/. S/Jl/ttal

The DOE t i i m d i D«cUioQ and Orderconcerning » A p p l j c a t t O f l J f o r Refundsubmi t t ed in t h a . G u l f Oil Corporat ion*pect*l refund proceeding. Eacha p p l i c a : . o n was a p p r o v e d u*ing ap r e i a m p u o n of i n j u r y . The *um of ther e f u n d ! grimed in ihn D ecu ion.Including (nlere*t Ii &J.938.Gul/Qi! Corpora lion/Luna ford Oil Co..Inc. et oL 9/1/69, RFW&-$3? tt ol.The DOE is sued a D e c i i i o o tnd Orderc once mm* f i v e A p p l i c a t i o n * for Refunds ubmi t t ed ID the Cul/ Oil C o r p o r a t i o nsp e c ia l refund proceeding ThiA p p l i c a t i o n s were a p p r o v e d u i lng ip r e s u m p t i o n of injury. The sum of therefund* granted tn (Jus Decision. whichincludes both principal ind intere s t iiW.4M.C

FsriarW RaTcbter / VoL 54, No. 214 / Tu**day. November 7. 19» / Notice*cm b* obtained only from tb*Ctnonnatt o f f i c e .CO* PUWTHtW t t f O M M - n C M 6OB e l l e Cantor, Technical LUiwn, RiskAB4«*ime&t Forua, (202] 47£-6?43.

fa ;heg o f 1987. EPA'i Risk Auft s s iu .-ntFono* p u b l i s h e d • report e n t i t l e d"Interim Procedure s f or E s l i n u f i r ? Risk*Associated wuh Expo sur e s to M i x t u r e sof C h ' ^ r n a f e d Dibenzo-p*niox!ni and *Dibenzofuram ( C D D s / C D F * ) . " ' T T i i ireport out l ined the toxic i ly equivalency' r ; : l c - ( T E T J method a?.d recommended(Lat EM use thi s method, OB in interimKMIS. in rick assessments Involvingmixtures o / C D D i ind CDFv Uporraccn:.widailon o f E T A ' i RiskAisessmer.; Council. the Agencyf - . r m a ' l y a d o p t e d thi i interim T E FprceeJure It !u,i bê n uied by EPA toaddress* v t r ' d y o f environment«lconfa o.:nt ton i o c i d f c t i invoKutR CDDcand CJF*.The TET method is *a in '.e runprocedure "or asses s ing ihe risksM s i t M i e d win •xpovu/ t t (o complexmixiures u f C D O s and C D F s . CDDs andCDFj con fu t e « f a m i l y of 210s i r u e l u / a l f y - r c l a i c d chfir.icalcompound*. I n c l u d i n g ^7*ft-i e l ro chIoTod:beruo-p-i* TSFprocedure allows tn/onuaUoo on aknown chemical to b* uitd In MMuiugre la led cheuiicaU wb«re IitUe or no dataexi iL Thja. la turn. p«rmit» thtrtweumect o/ both urctru>g«nk andnonurcino^ciuc nxlca involvinge x p o t u / e i t o m J x t u r t « o f COOtaiutcor*.In IU 1M7 report tb« Agencyeraphaiized lhat the m«thod wu interim•n rwi-irc. urged collecOoo of mdrcd r t f u i i i t v * exp«rimenul daU, Andr remitted i'ic!f to periodic review} ait-M riiy dtU were s o n T a i t d -th e p j s : d e o i d t f . van«,uc* .:es m !he Ud«.r

•:v- 1 TCK fc-hc.rcs Ai a rats!!.i- i iT.c; •«» *ligh'.:y J-/."- .̂ ni TTPm i s l e d . AJ a ru»u!l nui.*.er*>ad ;>l>«!nf . .enl T C r ' m c L i o d i e s i a i rd . T N . is- ..-r.'.iii i.-.d nancies -n j J J / « ^ : r t | th*l o x j c u I c g . ' C ' i l s i g n i f i c a n c emix ' . j r e i o f t^OUa and COFf.

To addreM this inu*. the A g e n c y I*da lix-nation pro|«a ondcr thf «wp4c**of NATO which wu atmed at i dop t iaga common, (nternadono) i«t oi TEf t fora i M r t t n j j riikj of cor.la.ninatioainvolving CDDs and C U F v Th« Forumreport iuued (ocWy, "Inler-m Procedu(«sf c r E s ' t r a d U n g Ri»ki A i S ' . c t a t e d withExpiiuns to Mixture s c,f Chlonn^tcdOibenzo-p-Oioxi^i mi •DibcruofWam( C D D i and CDFs) and 19U3 Upd*t«. ' isbaieu on that elrox L Mos t in:pori«Q;ly.EPA ha< a d o p t e d th e NATOI n t e m a l i o n a l T L P i / 8 8 ( I - T E F » / do f which d i f f e r fron U i £ C P A - T S - ' i / a ?c u r r e n t l y in use. L£* me origin*!ictteou. J-TEF* art ba»«d on. avaiUhks d e n t i / l e data and recognition o/ tbcvalue of international cons i s t ency lo tbaf i e l d . The Fomm report pre sent! ther a l i o n a l e . me thodo l ogy , and toxicityd a t a used to d e t r r m f n e c e r f a i r . new TEFvalue! and describes d i f f e r » n c « tbetween the 1967 and 1&9 f i g u r e s , tegeneral the e f f e c t of the m o d i f t c s t f o n i ial i k e l y (o be modert for tro*t eoicpl^xmixture*Tlw I-TEFs/89 repf«enl enimprovement in an already ueful riskassessment tool. However, the approachremain* Interim fa lutur* and should b«rcpUced with relevant experiaentaldart M tuch date became tviikbfc.Promiiing p r o p e f i fi bmug oiaek hi thisDatvd

Acting AsHittaiti AdminktiQtor for Remrchand Development.|FR Doc ao-2tto3 FiW ii-e-edc «.tl am)coot sa it

COWUI8S1ON

of Usw^aawol ind budge} far Kevfet*Oclot-r A3. 1 We.C o m m i j j i o n has tubotit ted. t iainform a l ion co l l e c t i on requirement* to0MB fo/ review and clearance unJceIhp P a p e r w o r k Kcduclf&n Ac*, of 1̂ 00 (44o.s.a uon-u f i f t c i * liib.*rJ L id fr^ni Ir.a C c m m h f i c n ' s w j p yr . Int ern i i ionai T r u n s c f ' p t ' u nSer'.;..S- (2»2! flr-3TOO. 2100 M S t f « IMV- Su;'« 140. Wj*hi.ve.i. WT 2003?.in fonr i i i^n on IMS*cor.Uci J - j J y Bo!f>y. F-der t l?S!3- P:rtcns iv ; t fr.;na to c crr/nenl onthe s e lO/ora tabon coQacdoascontact E y t e t t e F l y n n , O f f i c e o f

Management end Bed̂ e*. KoomNEOa W a i h h i f K m . DC 20603. ( 7̂51 393-3785.OMB Ntwt&r 3060-Q2W.Title: Ser. i ion eOMfb)— T h y i i c a l l yf f e m t ' u p p s d " S p e c i a l E J i f i i b i l i t yAcftun; Extens ion.: I n d i v i d L - u l s or household vesponse: On occasion.A.IIIUC/ Burden: 20Hoar*.

S: Section 90.S8fb)pravJdea Hui penant claiauJageligibib'ty in the Special EmergeacyRadio Senrice on ih* tmtis of baiccp h y i i c a U y handicapped oiiut prescvt• phyiidf l f l ' s Etatement bidicatt^ that(bey are handicapped, Submiasida ofthJ« tn f onna t j on it neeeAaary toeosora that frequencieA itsened forl i c ens in f t to hand i capped individwbare not licensed to aoc fhandicappcdpencils. The ConmlsiJon tuet tktin format ion to di lcrmiot tba•ligibi t i ty of app l i caaU for licemea ong p K d ' f i cOMB Nuaibefi 306(MJaa.Title; Sectioo 90-U9(b)— S o p p l e a e o d lf n f o r a i t l o n lo be RoulineJy Sobn f t t cdwith A p p l i c a t i c r j (Non type-*ccept«dequipment}.Respondent* S t a t e or fecalj o v c r o n w o ' i . n o o - p J M / i t butitntkuu,end business* i (induding p*»Ubustnesse*)Frequency ofResponte: Oa occjsioa.Estimated AJWUQ! Burden: 100Responies: 34 Hour*,A'ee^j am/ /Aes.- PrecUcally «U t e J l aIr a DJ mill ing e q u i p j o f n t used In thaicountry i* manufactured to ccrUintechnical *4>ecirtcation* which. (OAbUft (o be designated u "typc-accept«d"by FCC laboratey ptnoantL Socb a.deaignitieui shows the purcbaur thatIhe equipment U capable olper fonniag within certain loleraaccathat Umit the teterfcrtoc* potenu*! ofthe device. For the few applicant*propoaing lo us« truumittaiitquiproent not proven lo meet lh«*Sspec l t i caUoRc, a t f e s c r f p t l u n of thepropctcd e q u t p m f i t i t U rtquircd. Thainformation col l ided is used by FCCengineer* to determine th*i r . ' c r f e r u r . c e po t en t ia l of the poperation.

Tit.'*: Sec t ion 00.138! J * tj—M o d i f i c a t i o n o f L l a T . s e ,Action. Exte.nton.^ f«W0.*fe St4Vj tovenunertu. Ron- p r o f i t i n t - t f .:sr. ̂ 1

E P A - T E O « / 8 7 l - T E Q a / 8 9

S O U R C ED A T A ( p p «

2378 - 1C DOOlhvr T C O D *2378 -P«CDO»

2378 - H x C D D aOlhw H x C O O a2378 - H p C D DOlhar H p C D O tOCDD

0.010.0660.00390

2378 -Olh*r12378

23478Oih«r2370 -Olh»r2378 -Olh*rO C D F

T C D FT C D F »P « C D FP « C O FP » C D F »H x C D F >H a C O F *H p C D F »H p C D F ,

0.000370.00330.000190

R « l i f « n c « : S m i t h , 1989.4. T o x i d t y equivalents Jn a pentachiorophenol wood treatment sitesoil sample.

12

111. U p d a t e of E P A - T E F s / 8 7 :A d o p t i n g the 5-TER89 SchemeA. S i m i l a r i t i e s Between l - T E F s / 8 9 and E P A - T E F s / 8 ?T a b l e 3 d i s p l a y s the 1 - T E F & 8 9 and she E P A - T E F s / 8 7 .The two sets of TEFs have several concepts m common. T h e y share Jheconceptual Iramework of the TEF approach. T h a i i s , the s tructure-act ivi tyr e l a t i o n s h i p is assumed to be s u f l i c i e n t l y strong that estimates of the 'long-term t o x i c i t y ol m i n i m a l l y te s ted congeners o* COOa'CDFs can b©reasonably in f err ed on the basis of available

2.3,7,8-TCODOther TCOOs,.Other PeCDOs

3 7 S - H » f C D O sOther HxCDOs.,.Other HpCDOs

OCDDMono-. QK and TnCDFs

JCDfs1.2,3,7.8-PeCQF2,3,4,7.S-PeCOFOther P^CDFs3378-HxCDFs

2378-HpCDFsOtner HpCOfs

0.010-50.0050.040.00040.00?0.0000*000.1O.OOJ0.10.)C.OOJ0.0 J0.00010-00?0.00001

0.500.)00-0700.00100.1

0.050.500.100.010

; Adapted torn NA7Q/CCMSIn as s igning TEFs, p r i o r i t y i s general ly given to ttie results itom long-term.whole-animal s tudies f o l l o w e d by the results 1rom short-term, whole-animals tudies. Among the remaining short-term in vivo and 1.0 vrf/o data, pr ior i ty isgenera l ly given to the results ol enzyme induction studies. T h i s is due io the

...... . :.:; ... qu..:,:~."---~-~: ., .... ~:.-·: .~•:rt.~•.~ .. - ~- .. ,•.,: - - -:-~--:-_:. : .. ..;;· . ... :.. "! .:-:.:·'." • • • w ~ •

... ., .. -.-~.

1 C'-1" )'(\, 1 1~~Ni

I \0 ~

(,C)'1 ';) (:/\ 2, <

:.., 3,-,, S - Tc. t> D

0 l '.-:..' 1 c.. D D '.;

2,1~1,i-?~ C.1)1)

1,-\:vv-"1 'i' e c. DO~

lj1J7,i- \.{)(.C.t>D

o\ \v,.,\ \\ i< c.. 01) s.

'-), 7, i - \.I {l CI)\) ~v-, Hf ti>\)

0Ct>D

1- 3 7 o - Tc"'-~ , / ' lJ V

~ 1,._;__, Tc. b V

2 , ?i , 4, 7, t -Pe ( b~ 1, i., '2_i, 1, f)-f'e_c 'b\= o.\: Iv.,• f'e C.t) ~ 5

z.l~, 1, i - t\)l (_\)V-o1 ~ \l-,,_ C.t>'i= :5

1-1 3 / 1 , i- u.~.c~r -c,l\v.. t\.eC.Df s __ _

f. :.>f {\ F °" c..-i ,_,,

0.05

o.cis

0.07

0.9~

o.3 0.7

o.s C).1:)

O.C>3 o.91

o.ot.f 0, 0 I.{

o. ~z_

0U ~ri\ m e--:"od

f

o. o I