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## A-90-1 9 ll-F-1 3

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•<*ce ^ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y WASHINGTON , O.C . 2046 3



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### 7 199 OfFCEO P AiRANOIUOUTlON

SURTECT : HO

NBenefit s Analysi s FROM : Thoma s C . Kierna :

DeputyAssistan t Administrato r fo r Ai r an

d Radiatio n TO : Frank Hodsol l

DeputyDirecto r fo r Managemen t Offic e c f Managemen t an d Budge t Attache d i s a draf t documen t representing the Agency' s effor t t o utiliz e availabl e dat a t o estimat e benefit s o f variou s HO Noptions . Whil e w e have attempted t o mak e reasonabl e assumption s wher e possible , th e fundamenta l lac k o f key informatio n relate d t o exposur e an d toxicityo f HO

Nchemical s an

d the complexit yo f the analysi s mus t b e kep t i n mind . Th e documen t describe s thes e uncertaintie s an d limitation s indetail . Agencyscientists , including the Offic e o f Researchan d Development , believ e tha t thes e limitation s canno t b e overstated . In reviewing thi s documen t i t i s importan t t o realiz e tha t forma l benefit s analysi s i s onl yone facto r t o be considere d i n decisio n making . Other , les s uncertai ninformation , provid e a n additiona l basi s fo r decisions . Thes e include the exten t o f overal l amissio n reduction , th e cos t pe r tono f thes e reduction* , th e exten t o f existing control , th e relation o f facilitie s t o populatio n center s an d consistencywit hothe r programs . W e can discus s the rol e o f thi s attempted benefit s assessmen t an

d thes e othe r decisio n factor s a t our meeting next week . Our apologie s fo r th e additiona l tim e require d t o generat e thi s analysis .P. 3

I*

HO NBENEFIT S ASSESSMENT INTRODUCTIO

N Thi s analysi s ha s bee n conducte d a t OMB' s reques t t o determin e the exten t t o whic hconclusion s ca nb e draw n fro m availabl e dat a concerning the ne t benefit s an d cost s o f the Hazardou s Organi c NESHAP (HON) . Whil e th e Agenc yha s attempte d t o mak e reasonabl e assumption s wher e possible , th e fundamenta l lac k o f ke

yinformatio n relate d t o exposur e an d toxicit yo f HO

N chemicals , th e complexit yo f th e analysi s and time constraint s strongl ylimi t th e utilit yo f th e results . Agenc yscientists , including th e Offic e o f Researc han d Development , believ e tha t thes e limitation s canno t b e overstated . I n particular , the availabl e informatio no nemission s o f specifi c HO

Nchemical s fromemissio n point s d o no t provid e an adequat e basi s fo r calculating populatio n exposure . Th e fac t tha t the emission s dat a ar e limite d t o a subse t o f emissio n points , the limitation s i n th e toxicit ydat a bas e an d a rang e o f othe r factor s describe d belo wal l contribut e t o th e grea t uncertaintysurrounding thes e estimates . I naddition , the lac k o f dat a an

d availabl e methodologyfo r endpoint s othe r thancance r mortalit yresul t i n a failur e t o includ e potentia l benefit s fo r noncance r healt hendpoints . Wit hthes e broad caution s i n mind , th e following presentatio n provide s a mor e detaile d discussio no f uncertaintie s inheren t i n th e analysis . Evaluatio n o f Exposur e Acomplet e analysi s woul d requir e knowledg e o f source specifi c speciate d emissio ndat a (i.e . a knowledg e o f bot hthe amoun t an

d identit yo f chemical s being emitte d fromsources ) a s wel l a s informatio n o n the locatio nan d activitie s o f individual s aroun d eachHO

Nfacility . Thes e dat a woul d b e necessaryt o suppor t appropriat e characterizatio no f exposur e t o individual s aroun d HO Nsources . Alternatively , comprehensiv e measure d o r monitore d dat a woul d b e require d t o characteriz e th e exposure s o f suc hindividuals . Becaus e o f th e broad rang e o f chemical s an d source s covere d b

yth e HO

N(abou t 11 0 liste d hazardou s ai r pollutant s - HAP s - fro m32 4 know

n facilities) , suc ha n assessmen t i s prohibitivel ycomplex . Moreove r existing dat a ar e insufficien t t o suppor t suchan analysis . Recognizing tha t a reliabl e measur e o f benefit s wa s no t possible , th e Agenc yinstead examine d th e limite d estimate d emission s dat a availabl e fro ma subse t o f pollutant s an d emission point s a t 8 8 facilities , i norde r t o provid e some insigh t int o the rang e o f value s whic hth e benefit s mayencompass . A s such , the analysi s canno t be describe d a s a tru e assessmen t o f the benefit s o f th e HO

Nrule . I t i s critica l i nevaluating thi sP. 4

analysi s tha t th e limitation s an d range s o f uncertaint ydescribe d i n thi s repor t b e kep t i nmind . Evaluatio n o f Healt hEndpoint s Th e analysi s ha s als o bee nlimite d b yth e lac k o f significan t toxicit ydat a o n man yHO Npollutants . Becaus e o f limitation s i n methodology , the asssessmen t focuse d o ncance r incidence , relying upo n th e availabl e carcinogenicit ydata . Les s than hal f o f th e 11 0 HAP s hav e bee n teste d fo r carcinogenicity . Fo r mos t chemical s wit hquantitativ e ris k estimates , potency estimate s rel yupo n anima l dose-respons e data , an d th e Agencyha s use d uni t ris k estimate s develope d i n complianc e wit hit s Cance r Assessmen t Guidelines . Wit hrespec t t o noncance r effect s sucha s developmenta l toxicit yo r neurotoxicity , adequat e dat a exis t t o asses s ris k fo r eve n fewe r HO

Npollutants . Thu s th e ful l rang e o f healt hbenefit s canno t b e characterized . Whil e availabl e methodologie s d o no t permi t a quantitativ e assessmen t o f noncance r effects , thi s benefit s assessmen t present s some dat a suggesting tha t exposure s t o man yHO Nchemical s excee d benchmar k level s generall y recognize d a s indicator s o f potentia l risk . Uncertaintie s I t mus t b e kep t i n mind whe nreviewing thi s benefit s assessmen t tha t th e result s ar e containe d withi nbroa d range s o f uncertainty , an

d tha t i t remain s difficul t eve nt o characteriz e th e bound s o f thos e ranges . Whil e th e Agencybelieve s tha t costs , whic har e bette r understood , ar e likel yoverstate d (se e below) , the benefi t analyse s incorporat e a variet yo f variables , some o f whic hmayb e overstated , an d some understated . I naddition , an unknow n portio n o f th e potentia l ris k ha s bee nlef t unquantifie d an d uncharacterized . Th e following i s a genera l summaryo f specifi c uncertaintie s inheren t i n thi s analysis :

o Th e us e o f uni t ris k estimate s (URE s - i.e . potency factors ) fo r carcinogen s woul d ten d t o overstat e ris k t o an unknow

n degree , sinc e potencyfactor s ar e estimate s o f upper-bound ris k fo r low-dos e exposures . o 198 0 censu s dat a wa s use d i n the analysis . The populatio n ha s grow nsinc e 1980 ; therefor e mor e peopl e woul d b e expecte d t o experienc e advers e healt heffects . o Ther e exis t littl e dat a o n identificatio n o f specifi c chemical s emitte d an d th e amount s o f thos e chemical s emitte d fo r individua l HO Nfacilities . Assumption s haveP. 5

bee n mad e for thi s analysi s whic hmayresul t i na highl yinaccurat e portraya l o f tru e risk . o In determining populatio nexposure , a screening mode l wa s use d t o estimat e th e numbe r o f peopl e living withi n 5 0 k mo f the subse t o f 8 8 facilities . Thi s subse t wa s selecte d fo r modeling becaus e facilit ylocation s (latitude s an

d longitudes ) wer e known . I t i s no t know n howrepresentative thos e facilitie s ar e o f al l HO N facilities . o Th e ris k analysi s provide s estimate s o f th e ris k associate d wit hexposur e t o 2 8 percen t o f proces s ven t emission s an

d 2 0 percen t o f wastewate r emissions . Thi s i s onl ya smal l subse t o f emission s from al l HO N facilities . o Th e emissio n estimate s wer e estimate d fo r chemica l compound s tha t ar e eithe r products , co-products , o r by

product s o f the process . Compound s tha t ar e presen t i n the feedstoc k o r tha t ar e intermediate s produce d during the proces s ar e no t accounte d for . o Cance r ris k include s estimate s fo r onl ythos e compound s tha t ar e designate d known , probable , o r possibl e human carcinogens . Compound s wit hinsufficen t dat a t o determin e carcinogenicit yar e excluded . o Synergism s an

d antagonism s among hazardou s ai r pollutant s (HAPs ) wer e no t considere d i nth e analysis . Factor s Tha t Lead t o Overestimatio no f Cos t o Cos t estimate s assume on e contro l devic e fo r eac h emissio n poin t a t a facility . I n practice , point s ar e ofte n combine d fo r cheape r co-contro l (i.e . severa l line s mayven t t o on e incinerator) . o Cos t estimate s giv e n o credi t fo r cos t saving s du e t o emission s averaging . o Estimate s assume th e mos t expensiv e mean s o f compliance . o Cos t estimate s d o no t tak e int o accoun t tha t th e standard use s the tota l resourc e effectivenes s (TRE ) forma t fo r vents , whic hallow s facilitie s t o compl y throughchange s i n equipmen t o r operation s a t lowe r cost .P. 6 

# "AF T

ESTIMATIN

GEXPOSUR E Human Exposur e Mode l Anumerica l expressio n o f publi c exposure , i.e . o f the number s o f peopl e expose d t o variou s predicte d concentration s o f HA P compounds , i s neede d t o hel p estimat e th e benefit s o f controlling HAP emission s tha t ar e release d int o the ambien t air . The numerica l expressio no f publi c exposur e i s base d o n two estimates : (1 ) a n estimat e o f th e magnitud e an d locatio no f annua l averag e ai r concentration s o f the HAP emission s nea r emitting sources ; an d (2 ) anestimat e o f th e numbe r o f peopl e livin g nea r emitting sources . The Huma n Exposur e Mode l (HEM ) wa s use d t o mak e thes e quantitative estimate s o f publi c exposure . Th e HE Mconsist s o f a n atmospheri c dispersio nmode l tha t include s meteorologica l dat a (Nationa l Weathe r Service ) an d populatio ndistributio nestimate s based on 198 0 Bureau o f Censu s dat a t o calculat e publi c exposure . The dispersio n mode l i nHE Muse d dat a fo r mode l plant s tha t wer e modele d a t eac ho f 8 8 HO Nfacilit ylocation s (latitude an d longitude) . Th e mode l plan t i s constructe d t o represen t realisti c plan t parameter s wher e actua l parameter s vary . Input s t o th e HE M dispersio n mode l fo r eac hmode l plan t included : (1 ) mode l plan t emissio n rat e fo r tota l HA P fro mwast e wate r treatmen t an d proces s vents ; (2 ) releas e heigh t o f 1 0 meter s fo r proces s vents ; zer o meter s fo r wast e water ; (3 ) exi t velocitie s o f one (uncontrolled ) an

d fiftee n(controlled ) meters/second fo r vent s an d 0. 1 fo r wast e water ; (4 ) stac k ga s temperature s o f 29 8 (uncontrolled ) an

d 99 9 (contolled ) degree s Kelvin ; (5 ) building cross-sectiona l are a o f te nsquar e meters ; an d (6 ) fo r proces s vents , insid e stac k diamete r o f 1. 0 meter . Based o n specificatio n o f a latitud e an d longitud e t o defin e eachplant' s location , meteorologica l dat a (a nannua l averag e estimat e o f fiv e year s wort ho f dat a i s typical ) fro mthe neares t airpor t o f th e 31 4 airport s containe d i nth e HE Mi s brough t int o the analysis . The meteorologica l dat a a s wel l a s the mode l plan t emissio n an

d stac k informatio nar e use d t o estimat e the concentratio n an

d distributio n o f HAP fromdistance s o f 20 0 mt o 5 0 k mfro mth e emitting source . Specifying th e latitud e an d longitude als o bring s int o th e analysi s th e populatio n distributio n nea r th e plant . The populatio n databas e consist s o f populatio ncentroi d location s an

d th e 198 0 populatio n rrepresente d b yeachcentroid . Acentroi d i s th e populatio nweighte d cente r o f a censu s uni t an d b ydefinitio n peopl e generall ylive close r t o an d furthe r fro

m the emitting sourc e tha nth e centroid . Censu s unit s var yi nsiz e fro ma citybloc k t o ove r 30 0 squar e miles . HE Midentifie s theP. 7

• • 

# ;-l

censu s unit s tha t fal l withi na 5 0 Je mradiu s (abou t 3 0 miles ) o f the emitting source . Th e HEMmultiplie s the concentratio no f HA P a t groun

d leve l a t eac ho f 16 0 receptor s aroun d th e plan t b

yth e numbe r o f peopl e expose d t o tha t concentratio nt o produc e exposur e estimates . The HE Mtake s a

n annua l sna

p sho t o f ris k an

d therefor e assume s that : (1 ) condition s leading t o the predicte d concentration s d o no t chang e an

d thu s th e annua l averag e exposur e fo r th e yea r i n questio n persist s fo r th e duratio no f th e averaging tim e o f th e UR E whic hi s a lifetime equa l t o 7 0 years , (2 ) peopl e sta ya t the same locatio n th e entir e yea r an d ar e expose d continuousl yt o the predicte d HA

P concentrations , (3 ) th e terrai n around th e plan t i s flat , an

d (4 ) concentration s o f HA P ar e th e same insid e an d outsid e o f th e residence . Exposur e Uncertaintie s Emission s pe r Mode l Plan t Neithe r th e amoun t o f specifi c HA P compound emitte d no r whic hHA

P ar e emitte d fro

mspecifi c facilitie s ar e known . Some o f the uncertaintie s associate d wit hth e mode l plan t include : representativenes s o f the mode l plan t —assuming tha t ambien t ai r begin s 20 0 meter s fro ma significan t emissio n poin t mayoverstat e exposur e fo r large r chemica l plant s an d understat e exposur e fo r smalle r chemica l plants ; th e locatio n o f emissio n point s abou t plan t property ; representativenes s o f emissio n poin t characteristics , e.g . stac k height , etc. ; representativenes s o f th e meteorologyfrom the neares t meteorologica l sit e t o tha t o f th e facility ; an

d ho wwel l the dispersio nmode l i n HE Mpredict s ambien t HA

P concentrations . Populatio n Exposur e Th e basi c assumption s implici t i n the methodologyar e tha t al l exposur e occur s a t people' s residences , tha t peopl e sta ya t th e same locatio n al l year , tha t the condition s tha t lea d t o the predicte d ambien t ai r concentration s remai n unchange d fo r the averaging time o f th e URE , e.g . 7 0 years , an d tha t th e concentration s ar e the sam e insid e an

d outsid e the residences . Fromthes e assumption s i t canb e see ntha t publi c exposur e i s no t base d o n actua l data . Th e Populatio n Th e following ar e relevan t t o the expose d population : o Studie s showtha t al l peopl e ar e no t equall y susceptibl e t o pollutio nan d cancer . Ther e i s no numerica l recognitio no f the "mos t susceptible " subse t o f th e populatio n exposed .P8 . 

### AT '

o Studie s showtha t whethe r o r no t exposur e t o a particula r carcinoge nresult s i n cance r maybe affected b ythe person' s exposur e t o othe r substances . The public' s exposur e t o othe r substance s i s no t numericall yrecognized . o Workplac e exposure s ar e no t numericall yapproximated . o Noninhalatio n exposure s ar e no t numericall y approximated . o Studie s showtha t ther e i s normall ya long latency perio d betwee nexposur e an d onse t o f cancer . Thi s ha s no t bee n numericall yrecognized . o Th e peopl e expose d ar e no t locate d b yactua l residences . Theyar e locate d i n th e Burea u o f Censu s dat a fo r 198 0 b

ypopulatio ncentroid s o f censu s districts . Ambien t Ai r Concentration s The following ar e relevan t t o th e estimate d ambien t ai r concentration s use d i n thi s analysis : o Fla t terrai n wa s assume d i n the dispersio nmodel . Concentration s muc hhighe r tha n thos e estimate d coul d resul t i f emission s impacte d o nelevate d terrai nnea r a plant . o The estimate d concentration s d o no t accoun t fo r th e additive impac t o f emission s fro mplant s locate d clos e t o on e another . o Meteorologica l dat a specifi c t o plan t site s ar e no t used i n th e dispersio n model . A s explained , meteorologica l dat a fromth e Nationa l Weathe r Servic e station , usuall yanairport , neares t th e plan t sit e ar e used . Site-specifi c meteorologica l dat a coul d resul t in significantl ydifferen t estimate s o f predicte d concentrations . o The emissio n rate s ar e base d o n assumption s abou t the concentration s o f specifi c HA P compound s i ntota l HA P sou p emissions .P. 9

i ' ' ' 

# '\ H

ESTIMATIN

GCANCE RINCIDENC E Ther e ar e a variet yo f effect s categorie s associate d wit h the emission s o f hazardou s ai r pollutant s (HAPs) . Thi s sectio n o f th e analysi s focuse s o n cance r incidenc e only . Annua l Cance r Incidenc e Th e expressio n o f ris k use d her e i s annua l cance r incidence , a measur e o f aggregat e risk . Aggregat e ris k i s the summatio no f risk s t o peopl e estimate d t o b e living withi n 5 0 k m o f an emitting sourc e fro mexposur e t o HAP s throughinhalation . I t i s calculate d b

ymultiplying (modele d ambien t concentration s o f th e pollutants ) x(HO

Nemissio n IUR ) x(tota l populatio nexposur e — th e su mo f th e numbe r o f peopl e expose d t o the rang e o f modele d ambien t concentration s time s thos e respectiv e concentrations) . Thi s estimat e reflect s the numbe r o f annua l exces s cancer s among th e tota l populatio n i f th e condition s leading t o th e exposur e d o no t chang e fromyea r t o year , an d th e man

yothe r assumption s require d b

yquantitativ e ris k assessmen t ar e correct . Thi s analysi s include s onl ythos e HAP s wit hcarcinogeni c classification s o f A , B , o r C (known , probable , o r possibl e human carcinogens) . O f 2 9 HAP s wit hA , B , o r C classification , 2 0 have inhalatio n uni t ris k estimate s (IUR ) upo n whic ht o bas e cance r ris k (th

e inhalatio n uni t ris k represent s the excess , lifetime cance r ris k du e t o the continuous , lifetime exposur e t o on e uni t ( 1 ug/m3 ) o f carcinogen . T o includ e the remaining 9 HAP s i n th e analysis , a defaul t IU Rwa s calculate d an d applie d t o thes e 9 HAP s base d o n the following rationale :

Th e existing IUR s appea r t o b e log normall y distributed . Therefore , the centra l tendencyo f thi s distributio n canb e approximate d b yusing th e geometri c mea n o r th e media nvalu e o f thi s distribution . Inthi s case , bot hvalue s wer e veryclos e (1.8xl0~ 5 vs . 2.0x10 " 5 , respectively) , bolstering th e geometri c mea na s a reasonabl e valu e t o us e a s th e defaul t value . The 2 9 HAP IUR s (including th e defaul t value ) wer e the n weighte d b

yapplying a valu e o f thei r estimate d emission . Th e estimate d emissio n value s wer e calculate d a s follows :

Th e amount s o f a nindividua l HA P foun d a s a product , co-product , o r by-produc t (regardles s o f process ) wer e estimate d fro

mth e HONdatabase . The rati o o f thi s amoun t t o tota l HAP emission s fro mthes e processe s wa s calculate d base d upo n stoichiometri c considerations . I n th e absenc e o f actua l emission s dat a fo r eachHAP , i t wa s assume d tha t th e proportio n o f HA P i n theP.1 0 

# TRAF T productio n proces s wa s simila r t o th e proportio no f HA P i n th e tota l HA

P emissio nstream . Th e 2 9 IUR s wer e weighte d b ythi s assume d emissio n proportio n normalize d t o th e tota l HAP emissions . The 2 9 HA P carcinogen s represente d 61 % o f tota l HA P emissions . The remaining 39 % woul d b e HAP s fo r whic h no dat a exist s t o classif ya HAP a s a carcinoge no r noncarcinoge n o r th e HAP ha s know nnoncance r effects . Th e weighte d averag e o f th e IUR s (2.4xl0~ 5 ) wa s chose na s the representativ e IU Rt o us e i n calculating th e cance r incidenc e du e t o HO

Nchemica l emissions . Incidenc e value s ar e presente d a s th e annua l cance r incidenc e values , the cance r incidenc e a t 60 % (becaus e i t i s assume d thes e HAP s represen t 61 % o f tota l emissions) , an

d th e cance r incidenc e a t 30 % an d 90% . Th e rang e o f value s i s appropriat e becaus e th e emission s o f a n individua l HAP from

a singl e sit e ma

yb e a s higha s 100 % o r a s lowa s zero . Cance r incidence s fo r variou s contro l option s wer e calculate d b

ymultiplying 2.4xl0" 5 b yth e populatio nexposur e estimate s fo r th e variou s options . Uncertaintie s Surrounding Uni t Ris k Estimat e Th e uni t ris k estimat e (URE ) i s use d b yEPAi nanalyse s o f carcinogens . I t i s define d a s th e uppe r bound lifetime cance r ris k occurring i n a hypothetica l populatio ni n whic hal l individual s ar e expose d throughou t thei r lifetime (assumed t o be 7 0 years ) t o a n averag e concentratio no f 1 ug/m 3 o f th e pollutan t i n th e ai r theybreathe . Th e ris k i s no t likel yt o b e highe r an d maybe significantl ylowe r than tha t indicate d b yth e URE . Uni t ris k est.imate s ca n be used fo r two purposes : (1 ) t o compar e the carcinogeni c potencyo f severa l agent s wit hon e another , an d (2 ) t o giv e a roughindicatio n o f th e publi c healt hris k tha t migh t be associate d wit hestimate d ai r exposur e t o thes e agents . Mos t uni t ris k estimate s ar e derive d from anima l studie s an

d ar e therefor e onl yapproximat e indicatio n o f th e actua l ris k i n population s expose d t o concentration s o f a carcinogen . Difference s betwee n specie s (lifespan , bod ysize , metabolism , immunologica l response , targe t sit e susceptibility) , a s wel l a s difference s withi n specie s (geneti c variation , diseas e state , diet) , ma

yresul t i n the actua l ris k being muc hdifferent . I n human populations , variation s occu r i ngeneti c composition , diet , living environment , an d activitypatterns . Some population s ma y demonstrat e a highe r susceptibilit ydu e t o certai nmetaboli c o r inheren t difference s i n thei r respons e t o the effect s o f carcinogens . Also , uni t ris k estimate s ar e base d o n exposur e t o a referen t 7 0 k

g adult . Ther e mayb e an increase d ris k wit h exposur e t o fetuses , children , o r othe r sensitiv e groups . Finally , human s ar e expose d t o a variet yo f compounds , an d the 8P.1 1 

# H

healt heffects , eithe r synergistic , additiv e o r antagnostic , o f exposur e t o comple xmixture s o f chemical s ar e no t known . The low-dos e extrapolatio nmode l use d an d it s applicatio n t o epidemiolog

yan d anima l dat a have bee nth e subjec t o f substantia l commen t b

yhealt hscientists . Th e uncertaintie s ar e larg e an d ar e to o comple xt o b e summarize d here . Significan t uncertaintie s associate d wit hthe URE include : (1 ) selectio no f dos e respons e model , (2 ) selectio n o f stud yuse d t o estimat e th e URE , (3 ) presenc e o r absenc e o f a threshold , (4 ) appropriatenes s o f anima l mode l t o represen t th e human population , (5 ) potencyo f complex mixtures , (6 ) individua l humanvariability .' <J L\ •

NON-CANCE RHEALTH EFFECT S Inhalatio n Referenc e Concentration s Althoughcance r i s o f grea t concer n a s a nadvers e healt h effec t associate d wit ha chemica l o r a mixtur e o f chemicals , man y othe r healt heffect s mayb e associate d wit hthes e exposures . Thes e effect s mayrang e fro msubtl e biochemical , physiological , o r pathologica l effect s t o gros s effect s suc ha s death . Th e effect s o f greates t concer nar e th e one s tha t ar e irreversibl e an

d impai r the norma l functioning o f th e individual . Some o f thes e effect s includ e respiratorytoxicity , developmenta l an d reproductiv e toxicity , centra l nervou s systemeffects , an d othe r systemi c effect s sucha s live r an d kidneytoxicity , cardiovascula r toxicity , an d immunotoxicity . Fo r chemical s tha t give ris e t o toxi c endpoint s othe r thancance r an d gen e mutations , ther e generall yappear s t o be a leve l o f exposur e belo wwhic hadvers e healt heffect s usuall yd o no t occur . I n evaluating noncance r risks , frequentl ya healt hbenchmar k i s compare d t o estimate d exposur e levels . Mos t often , the healt h benchmar k use d i s an inhalation : referenc e concentration . An inhalatio n referenc e concentratio n (RfC ) i s "a n estimat e (with uncertaint yspanning perhap s anorde r o f magnitude ) o f a dail y exposur e t o th e human populatio n (includin g sensitiv e subgroups ) tha t i s likel yt o b e withou t appreciabl e ris k o f deleteriou s effect s during a lifetime. " Whil e ther e i s increase d ris k o f advers e effect s a s exposur e exceed s the RfC , suc hexposur e doe s no t necessaril ymea n tha t advers e effect s wil l occur . The Rf C i s derive d fro

man identifiabl e no-observed-advers e effec t leve l (NOAEL ) o r lowest-observed-advers e effec t leve l (LOAEL ) fo r the critica l o r mos t sensitive effect . I f derive d fro man anima l study , the NOAE L o r LOAE L i s converte d t o a huma nequivalen t concentratio n (HEC ) t o accoun t fo r uncertaintie s i nth e extrapolatio n o f thi s concentratio n t o the genera l human population . Fo r example , uncertaint yfactor s ar e commonl yuse d t o accoun t fo r inter

- an d intraspecie s variability . Th e assessmen t o f noncance r healt heffect s associate d wit h chroni c exposure s t o HAP s i s base d o n a direc t compariso n o f th e chemical-specifi c healt hbenchmar k t o the predicte d annua l averag e ambien t concentration s a t recepto r location s aroun d a sourc e emitting HAP . Ambien t concentration s tha t ar e les s than the Rf C ar e no t likel yt o b e associate d wit hhealt hrisks . Th e probabilit ytha t advers e effect s maybe observe d i na human populatio n increase s a s the magnitud e o f exposur e increase s (concentratio n an

d duratio no f exposure ) an d i s affecte d b

ya specifi c individual' s susceptibility . Fo r th e estimat e o f cance r reductions , estimate s wer e mad e o f exposur e t o "HA

P soup " a t 8 8 plants . Thes e exposur e estimate s

1 0P.1 3

ca n be used t o estimat e exposure s t o concentration s greate r than Rf C level s befor e an d afte r regulatio ni f th e "HA P soup " canbe apportione d t o allowestimate s o f th e individua l pollutants . Whil e w e d o no t have individua l pollutan t estimate s fo r the 8 8 plant s o r fo r the nation a s a whol e w e d o have estimate s fo r nationa l productio n o f the 8 0 product s produce d i n facilitie s covere d b

yth e HO

Ntha t ar e themselve s HAPs . Th e HO Ndat a bas e wa s use d i n tw o differen t way s t o estimat e th e percentag e o f nationa l productio n associate d wit heac ho f th e 8 0 products . The firs t metho d count s the produc t onl ywhe ni t i s th e primary product . Th e secon d metho d include s th e produc t whethe r i t i s a primaryproduct , co-product , o r by-product . Eac ho f thes e two set s o f percentage s ar e use d t o apportio nth e "HA P soup " fo r the 8 8 plant s i n aggregate . Th e tw o method s bot hassume a proportiona l relationshi p betwee nemission s an d production . Thi s i s onl ya veryroug happroximation . The 1 6 pollutant s fo r whic hRfC s ar e currentl yavailabl e compris e roughl y25 % o f emission s b yth e firs t allocatio n procedur e an

d 15 % b ythe second . Th e RfC s fo r th e 1 6 pollutant s varyi n bot hthe critica l effec t an d th e magnitud e o f the actua l RfC . Onc e the 8 0 pollutant s ar e estimate d i naggregat e fo r the 8 8 facilities , distributio nspatiall yo f th e emission s i s quit e importan t becaus e RfC s ar e non-linea r wit hrespec t t o concentration . Thus , i f al l th e "HA P soup " a t a particula r facilit yi s on e pollutant , th e expose d populatio n wil l b e facin g a highe r concentratio n tha t i f th e "HA P soup " i s compose d o f tw o pollutant s wit hequa l shares . I t woul d b e anempirica l questio n a s t o whethe r ther e woul d b e mor e peopl e expose d t o concentration s above the RF C i nth e singl e pollutan t o r the two pollutan t scenario . Concentration s ar e highe r i nth e singl e pollutan t scenari o bu t pollutant-people-exposure s ar e greate r i n th e two pollutan t scenario . The thre e scenario s analyze d are : o On e pollutan t a t eac hfacilit y o On e pollutan t fo r proces s vent s an d anothe r fo r wastewate r o Thre e pollutant s pe r facilit ywit hequa l share s b y mass . Thes e scenario s wer e estimate d fo r th e aggregat e o f the 8 8 facilities . Thus , the thre e scenario s jus t describe d shoul d be interprete d i n terms o f averag e populatio ndistributio n an d dispersio n characteristic s acros s facilities . Fo r exampl e fo r the one pollutan t scenari o acetaldehyd e wa s no t matche d t o a 1 1P.1 4 

## npAF T

• • ; i . '•• ii particula r facilit ywit hth e requisit e fractio no f production . Instead , the fractio n o f it s productio nwa s applie d t o the populatio n expose d t o "HA P soup " abov e it s RF C fo r al l 8 8 facilities . Fo r th e thre e pollutan t scenari o the fractio no f it s productio n wa s applie d t o th e populatio nexpose d t o "HA P soup " thre e time s it s Rf C an d th e resul t multiplie d b ythree . Thes e scenario s ar e a t bes t roughapproximations . They ignor e case s wher e th e "HA P soup " i s comprise d o f mor e than thre e pollutants . O n th e othe r hand , theyals o ignor e th e cumulativ e exposur e fro

mmultipl e HO

Nfacilitie s an

d concentration s fro m non-HO Nsources . A s ca n b e see n fro

mth e tabl e th e result s ar e mor e dependen t o n th e metho d fo r determining percentag e o f nationa l productio n than fo r th e numbe r o f pollutant s pe r facilit yscenario . Al l si x combination s sho wa significan t numbe r o f peopl e expose d t o above Rf C concentration s i n th e absenc e o f regulation . Thi s significan t exposur e i s greatl yreduce d b yth e pollutan t reduction s associate d wit hth e optio ni nth e draf t propose d package . Remembe r thi s i s onl yfo r th e emission s associate d wit h th e wastewate r an

d proces s vent s fo r th e 8 8 facilities . Thes e result s shoul d b e reviewe d a s illustrative . Significan t reduction s t o exposure s above Rf C level s i n the baselin e ar e a likel youtcome o f regulation . However , knowledg e o f th e component s o f th e "HA P soup " i s require d fo r reliabl e estimates . Ou r inabilit yt o develo p reliabl e estimate s shoul d no t b e misconstrue d t o infe r thes e non-cance r healt heffect s ar e negligible .

1 2

### EXPOSURE S ABOV E RF C

1 Pollutan tpe rFacility 1 Pollutan tfo rProcess Vent s an d 1 fo r Wastewate rpe rFacility 3 Pollutant s pe rFacility (Equa l Shares) ALLOCATIO N BASE D O N PRIMAR YPRODUCTIO N {%) BASELIN E EXPOSURE S ABOV E TH E RFC 1,000,00 0 1,200,00 0 1.400,00 0 REDUCTION S I N

NUMBER S O F PEOPLE ABOV E 

### TH P RFC 800,00 0 900,00 0 1,200,00 0 ALLOCATIO N BASE D O N

PRODUCTS . CO-PRODUCT S & BY-PRODUCTS (% ) BASELIN E EXPOSURE S ABOV E TH E RFC 530,00 0 570,00 0 620,00 0 REDUCTJON S I N

NUMBER S O F PEOPL E ABOV E TH E RFC 440,00 0 480,00 0 560,00 0

Reduction s i n exposur e ar e estimate d fo rpollutan treductio n associate d wit h goin g fro m th e baselin e t o th e optio n i n th e draf tpropose d package .

# 1RAF T

MORTALITYVALUATIO

N The purpos e o f thi s sectio n i s t o describ e th e consequence s o f quantifying some o f th e anticipate d exposures , ris k reductions , an

d valuation s fromreduction s i nHAP emission s fo r a sampl e o f selecte d emissio npoint s an d effect s categories . The characteristic s o f th e sample , th e othe r aspect s o f th e methodology , results , a s wel l a s conclusion s an d qualification s ar e describe d below . Despit e incomplet e coverag e o f th e benefits , th e floo r fo r proces s vent s an

d optio n1 fo r wastewate r emissio n point s ar e preferre d o n allocativ e efficienc yground s t o presen t contro l levels . Dat a paucitie s (incomplet e coverag e o f th e benefits ) preclud e a definitv e statemen t a s t o whethe r furthe r control s fo r proces s vent s an

d wastewate r facilitie s improv e o r worse n economi c welfar e give n the criterio n o f allocativ e efficiency . Sampl e o f Emissions , Emissio n Points , an d Effect s Categorie s Thi s sectio n o f th e addendu mcharacterize s th e sampl e b y comparing the univers e o f emissions , emissio n points , an d effect s categorie s t o thos e o f th e sample . Emissions . Estimate d baselin e HA P emission s fo r th e HO Nar e portraye d b

yth e histogram s o nFigur e 1 . Thes e emission s come fromequipmen t leaks , proces s vents , storag e vessels , wastewate r collectio n an

d treatmen t operations , an d transfe r an

d loading operations . O f thi s total , nearl y90 % ar e fromproces s vent s an d wastewate r collectio n an d treatmen t operations , wit hproces s vent s accounting fo r nearl y50 % o f tota l baselin e emission s o f HAP fro mexisting sources . Th e proces s vent s an d wastewate r emissio n point s accoun t fo r a simila r portio n o f non-HAP VO C baselin e emissicns . Thi s sectio nfocuse s o n a subse t o f emission s fromthe proces s ven t an d wastewate r emissio npoints . Emissio n Points . T o conduc t exposur e analyses , estimat e ris k reductions , an d valu e thos e reductions , muc hunderlying dat a ar e required . On e suc hdat a elemen t i s th e geographi c location o f th e emissio n point s an d associate d emissions . Fo r example , t o translat e emissio n reduction s int o anticipate d concentration s an d exposures , locatio n specifi c emissions , meteorological , an d populatio n informatio n i s required . Suc hinformatio nwa s availabl e a t th e plan t leve l fo r a subse t o f proces s vent s an d wastewate r emissio n points . Thes e ar e plan t leve l emissio n point s wit hknow

n latitud e an

d longitud e coordinates . Th e subse t o f proces s vent s account s fo r 28 % o f baselin e emissions , 36 % o f annualize d contro l cos t an d 24 % o f al l individua l proces s vents . Th e subse t o f wastewate r emissio npoint s account s fo r 20 % o f HA P emissions , 29 % o f annualize d contro l cost , an d 14 % o f al l individua l wastewate r emissio npoints . 1 4
r > r~\» r T

# TOTA LHO N EMISSION S ByEmissio n Poin t Tota l HO N Emission s (Mg/yr) 300,00 0 250,00 0 200,00 0

150.00 0
100.00 0 50,00 0

0 S T W WE L P V 

# Emissio n Poin t 

# MvM. T R

T JP.1 8 

# n )RAFT

Effect s Categories . Ther e ar e a variet yo f effect s categorie s associate d wit hemission s o f HAP an d non-HAP VOCs . Thes e ar e displaye d on Tabl e 2 . Wit hreduction s i nHAP an d non HA P VO C emissions , ther e woul d b e anticipate d reduction s i n concentrations , exposures , effects , an d economi c damages . But , ther e i s als o th e potentia l fo r a nincreas e i n nationwid e NOx emission s i n th e fift hyea r o f 17,00 0 Mg a s wel l a s a n increas e i n C O emission s o f 1,76 0 Mg . However , thes e emissio nquantitie s ar e smal l i n compariso n t o th e corresponding decrease s i nHA P an d non-HAP VOC s emissions . Suc hdecrease s ar e estimate d nationall y a t 1,509,00 0 Mg fromproces s vent s an d wastewate r emissio n point s i n th e fift hyear . Thi s analysi s explicitl ymonetize s onl yon e effec t category : mortalit ydu e t o chroni c exposur e t o HAPs . Incomplet e coverag e o f th e benefit s doe s lea d t o ambiguitie s regarding th e allocative efficienc yaspect s o f contro l options .

1 6

•A .P.1 9

POTENTIA L PHYSICA L EFFECT S CATFHORIE S FO R

TH E HONREGULATIO N

Huma n Healt hEffect s Mortalit y

Du e t o chroni c Exposur e Mortalit yDu e t o Acut e Exposur e Morbidit yDu e t o Chroni c Exposur e Morbidit yDu e t o Acut e Exposur e Reduce d Activit yDay s Huma n Welfar e Effect s Worke r Productivit yLosse s Odor s Non-Huma n Biologica l Effect s Agricultur e Forestry Recreationa l Fishin g Ecosyste m Soilin g & Material s Damag e Residential/Commercial/Industria l Facilitie s Miscellaneou s Material s Climat e & Visibilit vEffecr s Loca l Visibilit y Non-Loca l Visibilit y Climat e Visibilit ya t Park s Transportatio n Safet y Direc t HA P

1 * 1 1 1 3

3 1

2 2 2 1

2 2

N A N A 3 N A N A VOC / Ozon e

3 2 2 1 1

1 2

1 2 3 3

1 1

N A N A 2 N A N A P M

2 2 1 1 2

2 3

2 2 2 2

1 1

2 2 2 2 2 Legend : 1 - Documente d effect . 2 - Effec t likely , minima l documentation . 3 - Effec t possible , no t documented . N A- no t applicable . * - quantifie d fo r th e HO NBenefi t Analysi s Extensio n

# >p A 

# C f

Result s fo r Sampl e o f Proces s Vent s an d Wastewate r Emissio n Point s Th e analytica l result s fo r th e sampl e o f proces s vent s an d wastewate r emissio n point s an d selecte d contro l option s ar e presente d below . Theyresul t froma combinatio no f emissio n reduction , exposure , an d ris k assessmen t result s wit hcontro l cos t an d a rang e o f mortalit yris k reductio nvaluatio n factor s ($1. 7 t o $9. 4 millio n pe r statistica l lif e save d i n 198 9 dollars) . Recogniz e th e benefi t analysi s onl ymonetize s mortalit yris k reduction s fromchroni c exposure s t o VO C HAPs . Th e morbidit yan d welfar e effect s categorie s exclusiv e o f huma n healt har e give nn o weigh t i n th e analysis . However , the benefit s o f non-HAP VO C emissio n reduction s ar e addresse d throughanimplici t valuatio n analysis . Th e result s presente d belo war e base d o n a rang e o f 3 0 - 90 % o f th e HAP-VO C strea m being carcinogenic .

1 8P.2 1

Proces s Vent s Sampl e Assumin g 30 % t o 90 % o f th e HAP S ar e Carcinogeni c Emissio n Reductio nRang e o f Reduce d Mg/yea r Floo r Optio n 2 NSP S Prop.Opt . Annua l Cos t

000' s $ 18,36 0 19,40 4 20,77 2 22,32 0 Incrementa l Reduce d Emission s Floo r Optio n 2 NSP S Prop.Opt .

Floo r Optio n 2 NSP S Prop.Opt . Mg/yea r

64,96 0 45 0 42 0 31 0 Incrementa l Contro l Cos t 000' s $ 18,36 0 1,04 4 1,36 8 1,54 8 64,96 0

65,40 8 65,82 8 66,13 6 Rang e o f Reduce d Incrementa l Incidenc e 7. 9 t o 23. 8 .002 5 t o .007 5 .002 3 t o .007 0 .017 8 t o .053 4 Rang e fo r Reduce d Cancer s Credi t 000' s $ 13,47 0 t o 223,46 0 4. 3 t o 70. 5 3. 9 t o 65. 8 30. 3 t o 502. 1 Cance r Incidenc e 7. 9 t o 23. 8 7. 9 t o 23. 8 7. 9 t o 23. 8 7. 9 t o 23. 8 Rang e o f Incrementa l Implici t Cost/Cance r Avoide d (000' s $ ) 77 0 t o 2,32 0 138,76 0 t o 416,27 0 196,55 0 t o 589,66 0 28,98 0 t o 86,96 0 Rang e fo r Implici t Valu e o f non-HAP VO C Reduction s ($/Mg ) < 0 t o 13 0 8,69 0 t o 9,28 0 11,63 0 t o 12,18 0 12,45 0 t o 18,07 0 Averag e Cost/Mg o f HAP Remove d 000' s $ Rang e o f Averag e Implici t Cost/Cance r Avoide d 000' s $

77 0 t o 2,32 0 82 0 t o 2,45 0 87 0 t o 2,62 0 94 0 t o 2,81 0

* Incidenc e reductio nestimate s ar e carrie dou t t o severa l digit s t o revea l th e calculate ddifference s betvee noptions . Th e numbe r o f digit s i s no t a nindicato r o f th e precisio no f th e estimates . Floo r Optio n 2 NSP S Prop.Optio n 28 0 30 0 32 0 34 0

1 9Wastewate r Sampl e Assuming 30 % t o 90 % o f the HAP s ar e Carcinogeni c Annua l Cos t 000' s $ Optio n 1 6,93 1 Emissio n Reductio nRang e o f Reduce d Mg/yea r Cance r Incidenc e 15,40 0 2. 4 t o 7. 1 Incrementa l Reduce dEmission s Mg/yea r ;tio n 1 15,40 0 Rang e o f Reduce d Incrementa l Incidenc e 2. 4 t o 7. 1 Rang e o f Incrementa l Implici t Cost/Cance r Avoide d (000' s $ ) 98 0 t o 293 0 Incrementa l Contro l Cos t 000' s $ Optio n 1 6,93 1 Rang e fo r Reduce d Cancer s Credi t 000' s $ 4,02 4 t o 66,75 0 Rang e fo r Implici t Valu e o f non-HAP VO C Reduction s ($/Mg ) < 0 t o 7 0

Optio n 1 Averag e Cost/Mg o f

HAP Remove d 000' s $

45 0 Rang e o f Averag e Implici t

Cost/Cance r Avoide d 000' s $ 98 0 t o 293 0

' Incidenc e reductio nestimate s ar e carrie dou t t o severa l digit s t o revea l the calculate ddifference s betwee noptions . Th e numbe r o f digit s i s no t anindicato r o f th e precisio no f th e estimates .

2 0• •-• ' •••-• » " ' i i Conclusion s an

d Qualification s Severa l finding s an d reservation s emerg e fromthi s analysis . o Th e strengt ho f thi s analysi s i s i nth e applicatio n o f exposure , risk , an

d economi c analysi s principles . o However , dat a paucitie s i nterm s concentratio nrespons e an d valuatio n function s preclud e definitiv e statement s o n th e allocativ e efficiencyaspect s o f contro l option s fo r proces s vents . o Th e ne t resul t o f th e aforementione d dat a gap s ar e t o understat e th e potentia l benefit s o f variou s contro l option s fo r thi s sampl e o f proces s vent s an d wastewate r emissio n points . o Despit e suc hlimitations , th e floo r fo r proces s vent s an d optio n 1 fo r wastewate r contro l appea r t o offe r gain s i n ne t economi c welfar e relativ e t o baselin e contro l levels . o Othe r contro l option s fo r proces s vent s an d wastewate r emissio n point s ma

yo r mayno t ad

d t o thes e ne t economi c welfar e gains .

2 1