Document XOp2k6ZzvRQ9XpKvYG4eEyVDJ

U.S. Environmental Protaction Agency Science Mviiory Board Environmental Health Camittee Hslogentted Organica Subcamittee Roeter for Novenfier 19-20 , 1997 Ravi*w Qf the Draft Final thinking Watar Criteria CDcunent for Polychlorinated Biphenyli Dr. John EBull. Chtirman. Profamor of Pharmacology and Toxicology, Univarsity of Kansas Medical Center, Kansas City, Kansas 66103^/J) 508 qC * Dr. Seymour Abrehcrcon, Vica-Chalcman, Profassor of Zoology and Ganatlea, repertmant of Zoology, Uhlvarsity ofc Wisconsin, Madison, Wisconsin 53709 subcommittee Members and Consultants Dr. Gaorga T. Bryan, Department of Hunan Oncology, K-4, Boas 531, 901 clinical Sc lanea Cantar, COO Highland Ava., univarsity of Wisconsin, Hsdlson, Wisconsin Dr. Larry Hanssn, Collsgs of vatarlnary Hsdlelna, Unlvarslty of Illinois, 2001 South Lincoln, ur&ana, Illinois 91801 Dr. Rorvid D. Hoed, Professor and Coordinator, Call and Oevelemantal Biology Section, Dspsrasnt of Biology, university of Alah--, and Principal Msoclata, B. El Hood and Associates. Consulting Toxiaoleglete, p. o. Boot lsa?, university, Alabsas 354M Dr. Urry Kaminsky, Otractoc w*daworth Center for Laboratories and Research, Nee York State esporenant of Health, Albany, New fork 12X1 Dr. Curtis Klaaasen, Professor of fhaoneoolagy and TDsloology, university of Kansas Madical Cantar, 39th and Rainbow Blvd., Kansas City, Kansas 56103 Dr. Con e. McMillan, Qialman, Ospartsant of Ph easeoology, nail 3S, university of Arkansas, Medical Sciences, 4X1 west Hsrkhas, St. Uttls Rock, Arkansas 72X5 Dr. Martha Radiks, University of Cincinnati Medical Cantor, Daparasnt of Rnviroansntal Health 3223 Man Avenue- -H. L. M, Cincinnati, Ohio 45257 Dr. Thaaaa Starr, cm. P, o. Bos 12137, Raaasrm Triangle park, North Carolina 27709 Otscutive Secretary Dr. C. Richard Gotham, Bcocutlve Secretary, ewlromantal Health Camittee. Science Advisory Beard (A-101F), u.S. Bsrlrenasntal Protection Agency oi m street, SW, Washington, DlC. X450 J MOWS 229996 I. Background! Appreciable levels o!PCb were detected in ground water samples from wells nter highly industrlalixed and landfill araaa of now Jersey. Surfaco water, sediments and fiah from a good number of rivers In the U.S. end In th# Croat Lakes wore found to contain PCBa. PCIa wore alto dotoetod in tap wator samples of a ftw communities which obtain their water from the highly contaminated Hudson River. However, none of the above ground water and municipal tap water surveys identi fied the specific Arochlor mixture In drinking water samples. There la only one published report which identified Aroclor 1016 mixture* at levels as high as 100 ng/1, in samples from a small upstate New fork public water supply system. The two reeervolrs of this waterworks* where Aroelor 1016 was also detected* used the Hudson River as their source of water. Higher chlorinated Aroclor mixtures were present in the Hudson River and-In one of the reservoirs but not detected in the finished drinking water samples from this community. Polyehlorlnated biphenyls pose speelsl problems with respect to establishing meaningful drinking water regulations. Thera are 209 different PCS isomers and it seems only 100 Individual isomers have been Identified st significant levels in commercial mixtures. Although toxicological studies have been performed on only s small number of the Aroclor mixtures* it is evident that there are significant differences In texielty between different Isomers and congeners. Xn particular* toxicity appears to Increase with increasing chlorine content* and Isomers which are axially substituted (positions 3.4*and 5) are more toxic than species that are substituted in positions 2 and 6. Consequently* the toxieity ef PCI mixtures depends on the isomer-specific composition of the mixture* as illustrated by the differing chronic toxlcltlea of various commercial PCS formulations* Xn addition* different KB preparations nay differ considerably in the content of toxic contaminants* such as polychlorinated dibensefurana. ror these reemena* toxicity data derived from s particular commercial PCI formulation are not directly applicable to other formulations* and may not even be applicable to different batehom of the aame formulation. Here Importantly* toxicity data from studies of commercial PCI formulations may have little relsvanee to the toxicity ef PCRe in drinking water beeauso the competition of environmental mixtures is markedly changed from the parent contaminant as a consequence of differing solubility and stability characteristics of the PCI (oners. Since the toxieity of a mixture could be dominated by a few relatively minor but highly toxie constituent isomers or contaminants* measurement of total(concentration Is not an adequate index for assessing the toxieity of PCI mixtures. MONS 224992 -2 II. IllUtl Bated on the Information on the toxicity of peta (mixtures laomart and congeners) and on their aolublllty and stability in' drinking water, la It possible to davtlop aanln^Cl accaptabla concantrations of PCBS In drinking vatar? III. Options Option 1 * Consider evaluating the toxicity of Individual laomera and derive criteria for drinking vatar for each ieoaer, if th# data perelt. This is a scientifically sound aethod for addreaslng the toxlelty of PCS alxtures. This approach is not feasible at present, both because leoaer-speelflc toxicity data are not available and because laoeer specific snelyalc of water Is not feasible on a routine basis* Option XX * Assuae thst ell PCI alxtures in the envlronaent are eoaposad entirely of the aost highly toxic lsoaer ,4',3' hexschloroblphenyl) and use this to eatlaeto acceptable level of Pds in drinking water. This will be the aost conservative, spprosch. While this would be certainly protective* this lsoaer Is a oinor eoeponent of aost forauletions and hoc low solubility in water. This option nay not be protective of the carcinogenic potential of PCIa because of the lack of data on the carelnogenie potential of this lsoaer. Option XXX * Assuae that a alxturo of PCSa in water ratslna an average toxleity thst is not greatly different free thst of the parent feraulstlon. Sasod on this sasueptlon, acceptable levela could be derived for coaasrclsl foraulatlona aa if they were individual cheelcals* One disadvantage to this approach is that it is usually difficult to identify whieh specific KBs feraulstlon(a) is (era) the source of PCBa in drinking watsr. *2S3lgjL2!l* Option XXX fa racoeaended. The key essuaption upon which this option rests (that KBs in water retsln an sversgo toxicity staller to the parent feraulstlon) aey not be true. However, it is unlikely to undereatlaete risk since the acre toxic higher chlorinated isoaers would have least wster transport potential, changes in ths acceptable levels of PCBs in drinking water or in the basic regulatory approach aay be possible in trie future as additional data and techniques beeoae available. MOMS 22*998 Pc:-`.i Zi !- 1 PCS cancer potency: Comperlaon with the human evidence (Dlaeuealon to bt addad to documtnt) The Agency'a canctr potency Cor PCIa (calculated fro* the Norback and Heltman ret atudy and reported In the Hay 1917 Drinking Hater Criteria Document to be 7.7 par mg/kg/d contlnuoua lifetime expoaure) conperea favorably to the number of eancar caaea aaen following the rice-oil Incident In Japan. Although more cancer caaea may be reported In the future* a rough calculation ean be made free currently available Information. The Drinking Hater criteria Document (page vi-14, attributed to Kurataune) reporte the average amount of PCta coneumed during the rlceoll Incident to be about 2 grama. Olvldlng thla by 70 kg (the weight of a typical adult) and by 29,100 daya (the numbvr of daya In a typical 70-year llfeapan), the average dally expoaure la eatlmated to be about 0.0C11 agAg/d. Multiplying thla by 7.7 per mgAg/d (the Agency'a cancer potency) ahowe the riak te be 147 per 100,000. In an espoaed population of. 1711 (page VI-31, attributed te Kurataune) approximately 14,9 esceaa cancer caaea are expected, Thla projection la not lnconaletent with the 7.39 exceaa liver cancer caaea reported te date (page VI-31, 9 obaerved mlnua 1.41 expected). Several eajor eoureaa of uncertainty in thla eomparlaon ahould be-notedt . a. The Agency*a potency eatleate la a plaualble upper bound, which would tend te evereatlmate the number of cancer caaea. b. The rice ell waa contaminated with polychlorinated dlbentofurana at a level 2S0 tlmea mere concentrated than In the commercial PCS product Raneehlor S00, To the extent that theae dlbenxefurana ere reaponelbie for the obaerved cancer caaaa, a projection baaed on baaed on tho cancer potency of PCIa alone would tend to undereatlaate the number of cancer caaea. a* Calculating an average dally expoeure prorated over an entire lifetime la very problematical, alnce the expoaure waa lntenae but ef ahmrt duratlen. in the abaeneo ef evidence te the contrary on PCSa, thla approach la conaletent with tha Agency*a cancer guldeltnea. Kevartheleea, It reoalna a aubatantlal eouree of uncertainty* MOMS 224999 Review of the Draft Cr inking water Criteria ojejnent for Polychlorinated Biphenyls {PCM) by the Halogenatsd Orgtnlci Subcarouttee Environmnttl Health Catmittee Science Advisory Board I. General Consents Tha regulation of KM In drinking water or, in fact, any environnental madia*, encountere many precises. Including several involving tha aaiatmg aclanclflc data baao. All ara deecrlbed in the crltarta dccunent. but virtually nona ara raaolvad. Ihaaa aclantlflc problws Ineluda tha eewglexity provided by 20t dlffarant congeners and leavers praaant In ooaareial KM mixtures. each with a dlffarant toxicityr tha praaanca of highly toxic njt-KM covenanta such aa polychlorinated dibanaofurana (PCBfth tha differential rataa of raaeval of Kt conganars fraa tha atwlrormane which laada to difference# In oongaimr prefilaa fraa thoaa of tha original pollutant aixtureei and tha lneo^lete knowledge of Individual KM eonganar tcsiclcy. tha draft criteria document auffara fraa a fallgra to elaarly Identify lta aclantlfle objectives. thua, aa reviewora. tha fcfccaaalttoe aaeOers encountered a ayriad of fact* that were not critically applied, either direct ly or to apparc a hypothaala for adogant regulatory declaIona, it act be Initially raaolvad whether tha abjective la to regulate Aroclora or n in tha atwlromant, lha luhcwlttei ballavaa that* la a need to aera preclaaly define what la aeant by tha tags "KMa*, in part Oecauae Aroclora aay or nay not be KM compounds and bacauaa of tha varied eq^oeltion of m mixtures. lha Subcommittee nm--nrta that tha wallable data on KM eonganara be developed on a ecale of eonganar toxicity, even if this la only an approximation in which data and professional jvdpont ara cabined, Any euch acala will be Any such acala wlU be la^arfact, however, for It is unlikely that the edvaraa health ounaaguancaa of thalldatida would bo detected. lha draft dooaont had Inswap ccnaidarably fnai a pravloua version. There ara, hoover, 101 aactiona that require axtanalva reviaiona before it repraaanta a scientifically adequate atat--nr of aalatlng knowledge. A nejor proolaa with dapteci V, VI and vin la that they ara out of data, for txarpla, In dapo V all of tha recant atzgetura activity relatlonahipe (SMt) for fOi bm bean ignored awn thcurti they ara dlaouaaad in detail in chapter Vtft lha Aaptor an hvmmn health affects i lariat ooegletely oeiu a aarlaa of papers in pwrlroaatntal Health hnaoactlvea (volvaaa Sf and SO) and tha MearlcaA Jouxnli ol~a*i7 wdlcina (wEin 3) that dlaouoa TuahoOfuQieng polaonlng' In Japan arifTalwn,--eis) occupational siqcauraa. Ihaao wkaalona severely ca^rotiaa tha quality of this chapter. In addition, It haa bean shown by two atudlae that tha major atlologtc agents In Vuaho and YuCheng polaonlng ara KtFa.1 This doaa not, howawr, abaolve KMa aa toxic agents end as contributors to sane of tha syrapto* of TUaho and Yucheng polalnlng. 10 HONS 225000